Marketing Clearance of Diagnostic Ultrasound Systems and Transducers : Guidance for Industry and Food and Drug Administration Staff

Administrative guidance, not enacted legislation. This captured publisher edition preserves the listed document and attachments; later developments are not independently consolidated.

Marketing Clearance of Diagnostic
Ultrasound Systems and
Transducers
Guidance for Industry and Food and
Drug Administration Staff
Document issued on February 21, 2023.
Document originally issued on June 27, 2019.
This document supersedes “Information for Manufacturers Seeking
Marketing Clearance of Diagnostic Ultrasound Systems and Transducers”
dated September 9, 2008.
For questions about this document, contact Office of Health Technology 8 (OHT8): Office of
Radiological Health at RadHealth@fda.hhs.gov or Office of Science and Engineering
Laboratories (OSEL), Keith Wear at 301-796-2538 or keith.wear@fda.hhs.gov. For questions
related to ultrasound systems and transducers intended for cardiovascular applications, contact
OHT2: Cardiovascular Devices at 301-796-7000. For questions related to ultrasound systems
and transducers intended for obstetrics and gynecological applications, contact OHT3:
Reproductive, Gastro‐Renal, Urological, General Hospital Device & Human Factors at 301-796-
6650.
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Devices and Radiological Health

Contains Nonbinding Recommendations
Preface
Public Comment
You may submit electronic comments and suggestions at any time for Agency consideration to
https://www.regulations.gov. Submit written comments to the Dockets Management Staff, Food
and Drug Administration, 5630 Fishers Lane, Room 1061, (HFA-305), Rockville, MD 20852-
1740. Identify all comments with the docket number FDA-2017-D-5372. Comments may not be
acted upon by the Agency until the document is next revised or updated.
Additional Copies
Additional copies are available from the Internet. You may also send an e-mail request to CDRH-
Guidance@fda.hhs.gov to receive a copy of the guidance. Please include the document number
GUI00000560 and complete title of the guidance in the request.

Contains Nonbinding Recommendations
Table of Contents
1 Introduction ............................................................................................................................... 1
2 Background ............................................................................................................................... 1
2.1 Safety of diagnostic ultrasound technology .................................................................... 1
2.2 Enforcement policy for modifications to legally marketed devices ............................... 2
2.3 Relevant Standards.......................................................................................................... 2
2.4 Preservation of existing 510(k) pathway and two-track approach, and use of Output
Display Standard, International Electrotechnical Commission (IEC) 60601-2-37 .................. 3
2.5 Radiation control ............................................................................................................. 4
3 Scope ......................................................................................................................................... 4
4 Definitions................................................................................................................................. 5
5 Policy ........................................................................................................................................ 6
5.1 Modifying a Legally Marketed Device ........................................................................... 6
5.1.1 Overview ................................................................................................................. 6
5.1.2 Compliance Policy .................................................................................................. 6
5.1.3 Examples of modifications for which FDA does not intend to enforce compliance
with the 510(k) requirement.............................................................................................. 11
5.2 510(k) Submissions....................................................................................................... 12
5.2.1 Indications for use ................................................................................................. 12
5.2.2 Device description ................................................................................................ 12
5.2.3 Predicate device comparison................................................................................. 13
5.2.4 Acoustic output ..................................................................................................... 14
5.2.5 General clinical safety and effectiveness .............................................................. 17
5.2.6 Labeling ................................................................................................................ 21
5.2.7 Track 1 recommendations ..................................................................................... 24
5.2.8 Track 3 recommendations ..................................................................................... 28
5.3 Additional Considerations ............................................................................................ 32
Appendix A List of Symbols Used in this Guidance................................................................. 33
Appendix B Format and Content of Acoustic Output Measurement and Labeling Records
Maintained in the Design History File .......................................................................................... 42
Appendix C Non-OEM Replacement Transducers and Remanufactured Transducers ............ 45
Appendix D Reprocessed “Single-Use Only” Transducers ...................................................... 47

Contains Nonbinding Recommendations
Appendix E Cleaning, Disinfection, and Sterilization .............................................................. 49
Appendix F Acoustic Output Reporting Examples .................................................................. 51
Appendix G Statistical Analyses ............................................................................................... 61

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Marketing Clearance of Diagnostic
Ultrasound Systems and Transducers
Guidance for Industry and Food and
Drug Administration Staff
This guidance represents the current thinking of the Food and Drug Administration (FDA or
Agency) on this topic. It does not establish any rights for any person and is not binding on
FDA or the public. You can use an alternative approach if it satisfies the requirements of the
applicable statutes and regulations. To discuss an alternative approach, contact the FDA staff
or Office responsible for this guidance as listed on the title page.
1 Introduction
This guidance document provides detailed recommendations for 510(k) submissions for diagnostic
ultrasound systems and transducers. In addition to outlining regulatory approaches for certain
diagnostic ultrasound devices, this guidance document describes the types of modifications to a
diagnostic ultrasound device for which FDA does not intend to enforce the requirement for a
new premarket notification (510(k)).
In general, FDA's guidance documents do not establish legally enforceable responsibilities.
Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only
as recommendations, unless specific regulatory or statutory requirements are cited. The use of
the word should in Agency guidance means that something is suggested or recommended, but
not required.
2 Background
2.1 Safety of diagnostic ultrasound technology
Exposure of tissues to intense levels of ultrasound that are well above the levels found in typical
diagnostic ultrasound devices can have significant biological effects. Therefore, determinations
of substantial equivalence have been made in part by comparing the appropriate acoustic output
levels of new devices to those of predicate devices of this type that were on the market prior to
May 28, 1976, the date of the Medical Device Amendments to the Federal Food, Drug, and
Cosmetic Act (FD&C Act or the Act), which are known as “preamendments devices.” The

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maximum acoustic output exposure levels of these preamendments devices are given in Table 3
of Section 5.2.7 of this guidance. The levels are derated using a general attenuation coefficient
for tissues, to permit a more accurate comparison between transducers of different frequencies
and focal lengths. For further information on regulatory acoustic output comparisons, see
O’Brien et al., Acoustic Output Upper Limit Proposition: Should upper limits be retained, J.
Ultrasound Med. 1335, 21, 1335-41 (2002); ME Stratmeyer, FDA Model for Regulatory
Purposes, Ultrasound in Med. & Biol. 15, 35-36 (1989); and GR Harris, Early Hydrophone
Work and Measurement of Output Exposure Limits at the U.S. Food and Drug Administration, in
Ultrasound in Med. & Biol., BIOLOGICAL EFFECTS OF ULTRASOUNDS; DEVELOPMENT OF SAFETY
GUIDELINES, PART 1: PERSONAL HISTORIES 26, 930-932 (W.L. Nyborg ed., 2000).
Because some laboratory studies have shown the potential for both thermal and mechanical
bioeffects at diagnostic acoustic output levels, and because of the particular concern for fetal
exposures (JS Abramowicz, Benefits and risks of ultrasound in pregnancy, Seminars in
Perinatology, 37, 295-300, (2013)), prudent use has been advocated by national and international
bodies concerned with medical ultrasound use and safety. In the United States, the American
Institute of Ultrasound in Medicine (AIUM) has endorsed the prudent use, as reflected in its
official statements.1 Two mechanisms have been recommended to help clinical users employ the
concept of prudent use: (1) providing the maximum levels of acoustic output in the device
labeling and (2) incorporating an acoustic output display on the device. This guidance
recognizes both of these mechanisms as potential methods of informing users about the acoustic
output of their device for the purpose of implementing the principle of As Low As Reasonably
Achievable (ALARA).
2.2 Enforcement policy for modifications to legally marketed
devices
This guidance describes an enforcement policy for modifications to legally marketed devices that
utilize the factors set forth in section 5.1.2 below.
2.3 Relevant Standards
FDA-recognized standards may be used to help demonstrate substantial equivalence in 510(k)
submissions. For more information regarding use of consensus standards, see FDA’s guidance
entitled “Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for
Medical Devices.”2 For the current edition of the FDA-recognized consensus standards
referenced in this document, see the FDA Recognized Consensus Standards Database.3
1 Available at https://www.aium.org/press/viewRelease.aspx?id=102
2 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/appropriate-use-
voluntary-consensus-standards-premarket-submissions-medical-devices
3 Available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfStandards/search.cfm

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2.4 Preservation of existing 510(k) pathway and two-track
approach, and use of Output Display Standard, International
Electrotechnical Commission (IEC) 60601-2-37
This guidance document retains a two-track approach, in which FDA’s recommendations for the
information you should include in your 510(k) submission depend on whether your device
follows Track 1 or Track 3. Please note that for historical reasons, there is no Track 2.
Track 1 recommendations are for devices that do not conform to the Output Display Standard in
IEC 60601-2-37 (IEC 60601-2-37 Medical electrical equipment - Part 2-37: Particular
requirements for the basic safety and essential performance of ultrasonic medical diagnostic and
monitoring equipment) and that follow FDA’s recommendations for application-specific acoustic
output levels. The acoustic output information should be included in the operator’s manual. A
tabular format (e.g., Examples 2 and 3 in Appendix F of this guidance) may be useful for this
purpose.
Track 3 recommendations are for devices that conform to the Output Display Standard in IEC
60601-2-37. The system should incorporate the output display according to IEC 60601-2-37,
and the labeling should include acoustic output information. A tabular format such as shown in
the example Acoustic output reporting table of IEC 60601-2-37 may be a useful example for this
purpose. Also, please note that information similar to that provided in IEC 60601-2-37 Acoustic
output table intended for 3rd parties, should be provided to 3rd parties (including the FDA) to
allow independent verification of the calculations of the Thermal Index (TI) and Mechanical
Index (MI) values for each operating mode. Section 5.2.4.1 of this guidance recommends the
basic elements of the acoustic output test methodology that should be described in the design
history file and/or 510(k) submission.
The term “Output Display Standard” now refers only to the CDRH-recognized IEC standard,
IEC 60601-2-37. Previously, the AIUM/NEMA standard (NEMA UD 3- Standard for Real-
Time Display of Thermal and Mechanical Acoustic Output Indices on Diagnostic Ultrasound
Equipment) was included when the term Output Display Standard was used. Since 2008, the
AIUM has withdrawn its equivalent standard, Standard for real-time display of thermal and
mechanical acoustic output indices on diagnostic ultrasound equipment. Please see the guidance
entitled “Appropriate Use of Voluntary Consensus Standards in Premarket Submissions for
Medical Devices” for detailed information on the use of consensus standards in your regulatory
submissions.4
4 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/appropriate-use-
voluntary-consensus-standards-premarket-submissions-medical-devices

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2.5 Radiation control
It is important to note that independent from the pathways described in this guidance for a new
or modified ultrasound device, manufacturers must continue to meet the following electronic
product radiation control requirements:5
· 21 CFR 1020.10 Television Receivers with Cathode Ray Tubes (For ultrasound products
incorporating a cathode ray tube display);
· 21 CFR 1002.20 Reporting of Accidental Radiation Occurrences;
· 21 CFR Part 1003 Notification of Defects or Failure to Comply; and
· 21 CFR Part 1004 Repurchase, Repairs, or Replacement of Electronic Products.
3 Scope
The following table provides a listing of the classifications containing diagnostic ultrasound
systems and transducers affected by this document:
Table 1: Diagnostic Ultrasound Classifications
Device Area CFR # Name Covered by Section 5.1
Modifications Policy?
Radiology 892.1550* Ultrasonic pulsed
doppler imaging system
Yes
Radiology 892.1560 Ultrasonic pulsed echo
imaging system
Yes
Radiology 892.1570 Diagnostic ultrasonic
transducer
Yes
Cardiovascular 870.1200 Diagnostic intravascular
catheter
No
Cardiovascular 870.2100 Cardiovascular blood
flowmeter
No
5 FDA amended the Electronic Product Radiation Control (EPRC) reporting requirements in 21 CFR 1002.1, for
diagnostic ultrasound devices, to remove reporting and recordkeeping requirements under 21 CFR 1002.10, 21 CFR
1002.11, 21 CFR 1002.12, and 21 CFR 1002.13 (88 FR 3638 available at
https://www.federalregister.gov/documents/2023/01/20/2023-00922/radiological-health-regulations-amendments-to-
records-and-reports-for-radiation-emitting-electronic)

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Cardiovascular 870.2330 Echocardiograph No
Cardiovascular 870.2880 Ultrasonic transducer No
Cardiovascular 870.2890 Vessel occlusion
transducer
No
Ob/Gyn 884.2660 Fetal ultrasonic monitor
and accessories
No
Ob/Gyn 884.2730 Home uterine activity
monitor
No
Ob/Gyn 884.2740 Perinatal monitoring
system and accessories
No
Ob/Gyn 884.2960 Obstetric ultrasonic
transducer and
accessories
No
Radiology 892.1540 Nonfetal ultrasonic
monitor
No
*Certain reusable devices within these regulations are subject to 82 FR 26807 (June 9, 2017) and are
therefore not within the scope of devices covered by the Section 5.1 modifications policy. (See
Sections 5.1.2 and 5.1.2.1.)
Note that the recommendations described in Section 5.2 regarding the content of 510(k)
submissions apply to device types denoted in the table above that are not covered by the
enforcement policy for modifications to legally marketed devices described in Section 5.1. If
you have any questions as to whether your device is covered by the optional modifications
pathway described in this guidance, please contact the appropriate review team in the Office of
Product Evaluation and Quality (OPEQ) in FDA.
4 Definitions
The definitions and formulae for certain technical terms used in this document are provided in
Appendix A. Unless explicitly noted in this section, the definitions and symbols provided are in
concurrence with equivalent definitions and symbols in IEC 62359 Ultrasonics - Field
characterization - Test methods for the determination of thermal and mechanical indices related
to medical diagnostic ultrasonic fields. At the manufacturer’s discretion, equivalent symbols
from IEC 60601-2-37 can be used in the labeling, but all symbols in the labeling should be
defined in your submission.

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5 Policy
5.1 Modifying a Legally Marketed Device
5.1.1 Overview
This section describes the Agency’s enforcement policy for certain modified ultrasound and
transducer devices (see Section 3; “Scope”) that utilize the factors set forth in Section 0. Section
5.1.35.1.3 below provides some examples of modifications that may have led to 510(k)
submissions in the past, but for which FDA does not intend to enforce compliance with the
510(k) requirement6 because the device modifications fall within the circumstances described in
Section 5.1.2.
After a 510(k) is cleared, certain modifications may trigger the requirement for another 510(k)
submission. See “Deciding When to Submit a 510(k) for a Change to an Existing Device,”7
“Deciding When to Submit a 510(k) for a Software Change to an Existing Device,”8 and “The
Abbreviated 510(k) Program.”9
5.1.2 Compliance Policy
FDA does not intend to enforce compliance with the 510(k) requirement for certain modified
ultrasound and transducer devices (that have already obtained an initial 510(k) clearance) when
all of the following apply:
1. The intended use of the modified device is not changed (see Section 5.1.2.1 for details);
2. The device is not a reusable device subject to the requirement for the submission of
reprocessing labeling and validation data (see Section 5.1.2.1 for details);
3. The modes of operation for the modified device are well-established (see Section 5.1.2.2
for details);
4. The modifications do not lead to acoustic outputs that exceed the recommended
maximum acoustic output levels (see Section 5.1.2.3 for details);
5. The modifications do not result in a range of ultrasound interrogation parameters outside
a well-known range (see Section 5.1.2.4 for details);
6. The modifications do not utilize novel mechanical or thermal effects for imaging or
measurements (see Section 0 for details);
7. The measurements and analyses are clearly described and the user can adjust the
associated control parameters (see Section 5.1.2.6 for details);
8. Transducer element check is performed (see Section 5.1.2.7 for details);
6 21 CFR 807.81(a)(3)
7 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/deciding-when-submit-
510k-change-existing-device
8 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/deciding-when-submit-
510k-software-change-existing-device
9 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/abbreviated-510k-
program

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9. Transducer surface temperature falls within a well-defined range (see Section 5.1.2.8 for
details); and
10. Appropriate transducer covers are recommended to users (see Section 5.1.2.9 for details).
5.1.2.1 Regarding the intended use of the device:
5.1.2.1.1 The modified device is indicated to obtain ultrasound images of or signals
from the body;
5.1.2.1.2 The device’s classification is listed in Table 1 of Section 3 of this
guidance as falling within the Section 5.1 modifications policy;
5.1.2.1.3 The device is not a reusable ultrasound bronchoscope (product code PSV)
subject to the requirement for the premarket submission of validated
reprocessing data and instructions [82 FR 26807 (June 9, 2017)];
5.1.2.1.4 The modifications do not introduce or affect intracardiac or intravascular
imaging, performed using catheter-based transducers;
5.1.2.1.5 The modifications introduce a new clinical application only if the clinical
application has been cleared in another model, manufactured by the same
manufacturer, with the same technological characteristics and indications
for use as those of the subject device, and within the circumstances
defined in Section 5.1.2;
5.1.2.1.6 The modifications do not introduce or affect indications that are disease-
or treatment-specific, and/or provide features, or labeling relevant to a
disease or treatment;
5.1.2.1.7 The modifications do not involve the marketing of the device for use with
a drug or contrast agent and do not affect any existing drug or contrast
agent indication;
5.1.2.1.8 The device is indicated for prescription use only; and
5.1.2.1.9 The modifications do not introduce sterile use where previously not
indicated, and do not affect previously indicated sterile uses.
5.1.2.2 Regarding the modes of operation of the device: The modifications do not introduce or
affect modes of operation other than the well-established ultrasound modes described in
Table 2, below.

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Table 2: Well-established ultrasound modes of operation
Mode of Operation Description
A-mode Signal visualization mode, based on ultrasound
reflection data in a single line of interrogation
B-mode (2D, extended field
of view 2D, and 3D)
Imaging mode, producing gray-scale ultrasound
images, based on ultrasound reflection
M-mode Signal visualization mode, based on ultrasound
reflection data, depicted as a function of time
Doppler Characterization of movement, based on the
Doppler frequency shift
CW (Continuous Wave) Audio signal, indicating movement in a line of
interrogation
Color Doppler Color-coded imaging, showing movement with
respect to the transducer axial direction
Spectral Doppler or Pulsed
Wave (PW)
Spectral signal, quantification of movement in
user-defined sample volumes
Power Doppler Color-coded imaging, showing movement with
no direction information
Combination Doppler Any combination of the above Doppler modes
Speckle-tracking Any form of characterization of movement in the
image based on spatial displacement of speckle,
including strain imaging
Tissue Harmonic Imaging Gray-scale imaging based on the harmonics of the
frequency of interrogation
Combination Modes Combination of the above modes of operation,
superimposed on the display

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Note 1: The modes of operation listed above in Table 2 are for ultrasound-based
tissue interrogations that utilize longitudinal waves.
Note 2: Any modification that introduces or affects modes of operation other than the
modes listed above in Table 2 is outside the scope of the compliance policy described
in Section 5.1.2. Examples of modes not included in Table 2 are shear wave
elastography, acoustic attenuation mapping, transmission based imaging, and sound
speed measurement.
5.1.2.3 Regarding the acoustic output of the device: The modifications do not lead to acoustic
outputs that exceed the recommended maximum acoustic output levels specified in Table
3 of Section 5.2.7 (Track 1) or Section 5.2.8 (Track 3).
5.1.2.4 Regarding the ultrasound interrogation parameters: The modifications do not result in a
range of ultrasound interrogation parameters outside the ranges specified below:10
Center frequency (fc) 1 – 20 MHz
Peak rarefactional pressure (pr) 0 – 7 MPa
Number of Cycles in Pulse 1 – 100
Pulse repetition frequency (PRF) 100 Hz – 20 kHz
Note 1: Restriction on number of cycles does not apply to CW Doppler and
coded excitation.
5.1.2.5 Regarding novel ultrasound effects: The modifications do not use ultrasound energy to
produce novel mechanical or thermal effects beyond those known to occur for the
imaging modes described in Table 2 of Section 5.1.2.2 above (e.g., acoustic radiation
force impulse imaging produces novel mechanical effects at levels above those associated
with imaging methods listed in Table 2). Also, the modifications do not affect any
cleared use of ultrasound energy to produce mechanical or thermal effects on tissue for
the purpose of tissue interrogation. In cases where the level of thermal or mechanical
effects could be increased as a result of a certain modification, please consult the Office
of Radiological Health (OHT8), Center for Devices and Radiological Health, FDA.
5.1.2.6 Regarding modifications to measurement and processing features:
10 FDA derived these parameter ranges from previously cleared and preamendments devices.

10
5.1.2.6.1 Other than radio frequency (RF) signal processing (including all the steps
necessary to convert RF data into displayable data), the image processing
is reversible or the original image is available to the user;
5.1.2.6.2 The user or facility is able to edit or adjust user-activated post-processing
applications that are used for measurements (e.g., segmentation and
registration);
5.1.2.6.3 Where possible, the user or facility should be able to edit assumed values,
parameters, or thresholds in equations or algorithms used to generate
additional outputs based on measurements of anatomical dimensions,
tissue velocity, or pixel intensity. For example, the user should be able to
adjust sensitivity (thresholds) in spectral Doppler for measurement of
resistance index (RI). The equations or algorithms and assumptions are
provided in the operator’s manual when appropriate (such as when it does
not reveal proprietary information). Manufacturers may choose to limit
users’ initial abilities to make such edits, for example, by requiring users
to call a customer support line to obtain a password. In instances that
editing capability is not provided for the user, such as due to the potential
for corruption of the original image, the manufacturer should provide the
justification for such exclusion in the Design History File.
For equations or algorithms that require fixed assumptions in order to be
reduced to readily solvable forms, the equations or algorithms and any
assumptions necessary to reduce the equations or algorithms should be
provided in the operator’s manual when appropriate (such as when it does
not reveal proprietary information); and,
5.1.2.6.4 The labeling provides complete information about processing or
compression algorithms used when appropriate (such as when it does not
reveal proprietary information). This includes, but is not limited to,
algorithms that perform spatial compounding, frequency compounding,
other speckle reduction, and phase aberration correction. The labeling
provides the name of the algorithm and a citation if it is published in an
archival format or a complete description of the method if it is not.
5.1.2.7 Regarding transducer element check: Device manufacturers implement appropriate
integrated tests of transducer performance each time a transducer is connected to the
main system or activated. The transducer performance test should be accessible by
competent technical personnel, such as operators or service personnel. While the FDA
appreciates that different performance specifications may be necessary for transducers
based on the application and system configuration, each device should include some level
of testing. For example, an impedance check of each transducer element may provide a
preliminary evaluation of the element integrity and function. Device manufacturers
implement methods to communicate the results of the transducer performance tests to the
operators, and identify regions of the image that have been compromised by transducer

11
malfunction. This integrated test feature would also generate a report on the performance
of the probe under test for documentation, generally including a list of elements or
smallest available patches of elements that have been compromised. This integrated test
should also be available to the operators to initiate any time when a particular probe is
suspected of failure. As described in AIUM: Routine Quality Assurance for Diagnostic
Ultrasound Equipment, American Institute of Ultrasound in Medicine, Laurel, MD, 2008
(AIUM 2008), transducer element checks are important to ensure proper performance of
the transducer for acquiring images or signals that provide the intended information for
the users. Such proper performance is critically dependent on the integrity of the
piezoelectric transducer elements in terms of their mechanical and electrical
configuration, and the subsequent transduction function.
5.1.2.8 Regarding the transducer surface temperature: The specifications in IEC 60601-2-37
regarding protection against excessive temperatures and other hazards from the
transducer assembly at the patient contact surface are met.
5.1.2.9 Regarding endocavity use and appropriate transducer covers: If the device is for
endocavity use, the labeling includes validated cleaning/disinfecting instructions and
identifies the appropriate sleeves, if available. Please see Appendix E of this guidance
for information on reprocessing of all types of transducers, including those for endocavity
use.
5.1.3 Examples of modifications for which FDA does not intend to enforce compliance
with the 510(k) requirement
The following are examples of device modifications for which FDA does not intend to enforce
compliance with the 510(k) requirement (assuming the factors outlined in Section 5.1.2 have
been used):
5.1.3.1 Adding Continuous-Wave (CW) and Pulsed-Wave (PW) Doppler interrogation methods
to the modes of operation of the device.
5.1.3.2 Adding an algorithm that measures the volume of an organ based on scientifically well-
established image segmentation and volume calculation methods. As described in
Section 5.1.2.6.4, the scientific basis of the algorithm should be disclosed to the users for
optimal usage of the measurement.
5.1.3.3 Adding a new transducer with similar indications for use and similar acoustic output as
one already cleared in the system. As described in Section 5.1.2.1.5, the new transducer
may have a new clinical application, if the particular clinical application (e.g., indication)
has been cleared for another transducer, manufactured by the same manufacturer.
5.1.3.4 Adding a B-mode noise reduction filter for general imaging use to a system. The
characteristics of the algorithm used for the noise reduction are defined in Section
5.1.2.6.

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Notwithstanding this compliance policy, manufacturers must continue to update Design History
Files and other records as appropriate (21 CFR 820.30(j)).
5.2 510(k) Submissions
This section applies to new or modified devices that are not covered by the enforcement policy
described in Section 5.1.2.
5.2.1 Indications for use
Previous versions of this guidance recommended that manufacturers provide extensive
documentation of individual transducer functions on the Indications for Use (IFU) form. Though
this transducer function information should still be made available in the operator’s manual,
FDA is no longer recommending transducer function tables be included on the IFU form.
General purpose diagnostic ultrasound systems are intended to provide images of or signals from
the inside of the body, and FDA recommends that they be indicated for such use accordingly.
However, all modes of operation and the clinical applications of the device should be specified in
the IFU statement. Also, the operator qualifications (e.g., appropriately trained healthcare
professional) and device use settings (e.g., hospital or home use) should be specified in the IFU
statement. Specialized systems may necessitate more specific indications for providing images
of or signals from the inside of a specific organ.
Highly specialized systems, systems with unique specific indications, and systems that provide
novel quantitative information may have a new intended use or may raise different safety or
effectiveness questions. These devices may require a Premarket Approval (PMA) application as
set forth in Section 515 of the FD&C Act and part 814 (21 CFR part 814) of the regulations or a
De Novo request for classification under Section 513(f)(2) of the FD&C Act.
5.2.2 Device description
5.2.2.1 In your 510(k) submission, you should provide a general description of the subject
device, including, but not limited to, model designation, design, patient contact materials,
and control panel and system operation. The following items should be addressed for
system operation (as applicable):
5.2.2.1.1 You should describe each transducer and its operation in each mode and
mode combination, including, but not limited to: (1) the transducer model
designation and type (e.g., mechanical sector, rectangular phased array,
curved linear array, annular phased array), (2) the size and spacing of
element(s), (3) geometrical configuration, (4) total number of elements in
the array, (5) array dimensions, (6) the maximum number of active
elements for a single pulse, if applicable, and (7) the nominal ultrasonic
frequency or frequencies of the transducer assembly.
5.2.2.1.2 You should describe the operating controls that can cause a change in the
radiated field (e.g., output, pulse repetition frequency, transmit focal

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length, sector angle, image rate, pulse duration, depth, and sample
volume). For a Track 1 device, you should describe the operating controls
and procedures necessary to change to an application or mode that has a
higher application-specific acoustic output level (see Table 3 of Section
5.2.7).
5.2.2.1.3 You should describe any unique features or technological characteristics
of the subject device.
5.2.2.1.4 You should specify which track is followed in the 510(k) submission (see
Section 5.2.4). Systems can use transducers that are of Track 1 or 3, but a
single transducer should be either exclusively Track 1 (Section 5.2.7) or
Track 3 (Section 5.2.8) for all applications with a specific model.
Exceptions may be considered in some cases (e.g., Transcranial Doppler
(TCD)). For consideration of a potential exception, please contact the
Office of Radiological Health (OHT8), Center for Devices and
Radiological Health, FDA.
5.2.3 Predicate device comparison
5.2.3.1 A 21 CFR 807.92 compliant 510(k) summary must identify comparable predicate
device(s) to which the subject device is being claimed to be substantially equivalent (21
CFR 807.92(a)(3)). Whenever possible, you should identify the 510(k) numbers for the
predicate device(s).
5.2.3.2 You should compare the subject device to the predicate device(s) in terms of key
technological features. We recommend you also discuss the differences and provide
supporting data, if applicable. In addition, you should provide the following (tabular
format is desirable):
5.2.3.2.1 indication(s) for use;
5.2.3.2.2 general device description (i.e., design, patient contact materials,
operational characteristics, and specifications);
5.2.3.2.3 acoustic output and device settings used;
5.2.3.2.4 general safety and effectiveness information; and
5.2.3.2.5 proposed and/or final labels, labeling, and promotional materials.
5.2.3.3 You should identify any accessories or kits intended for use with the device. For
accessories or kits, you should provide evidence of the predicate status of the designated

14
comparison device(s) (generally 510(k) number(s) or preamendments device status. See
FDA’s guidance entitled “Preamendment Status.”11
5.2.4 Acoustic output
Defined in Sections 5.2.7 and 5.2.8 are the "Tracks" a manufacturer of diagnostic ultrasound
equipment can follow to demonstrate the substantial equivalence of its ultrasound system with
respect to acoustic output. The derated global maximum acoustic output should not exceed
preamendments acoustic output exposure levels (see Table 3 of Section 5.2.7) unless the device
is operating under conditionally increased output (see below); i.e., derated ISPTA £720 mW/cm2,
and either MI £1.9 or derated ISPPA £190 W/cm2. Note the exception for ophthalmic use in
Section 5.2.8. Also note that the global maximum derated value is the global maximum value
after derating and not the derated value corresponding to the global maximum value measured in
water. Also, note that the value of IPA.3 at the position of global maximum MI (IPA.3@MI) may
be reported instead of ISPPA.3 if the global maximum MI is reported.
Some studies suggest that acoustic output beyond preamendments acoustic output exposure
levels may be warranted under certain conditions (Nightingale KR, Church CC, Harris GR, Wear
KA, Bailey MR, Carson PL, Jiang H, Sandstrum KL, Szabo TL, and Ziskin MC, Conditionally
increased acoustic pressures in nonfetal diagnostic ultrasound examinations without contrast
agents: a preliminary assessment, J. Ultrasound Med., 34, 1-41, 2015). If the manufacturer
wishes to include the capability for conditionally increased output beyond preamendments
acoustic output levels or the ophthalmic levels listed in Section 5.2.8 in a 510(k) submission,
discussion of the planned submission through a pre-submission12 is recommended.
The manufacturer should indicate that the acoustic output exposure levels were measured,
calculated, and derated following the most recently released revision of the FDA-recognized
consensus standard IEC 62359, along with a declaration of conformity. Alternatively, the
measurement procedure should be fully described. Any deviation from the methodologies
outlined in the IEC 62359 standard document should be fully described in terms of the differing
methodology used and be supported with validating data.
Note that pursuant to Section 514(c) of the Act, a person can use a standard recognized by FDA
to meet a premarket submission statutory requirement or other requirement under the Act to
which such standard is applicable and submit a declaration of conformity to FDA to certify the
device is in conformity with the standard.
11 Available at
https://www.fda.gov/medical-devices/quality-and-compliance-medical-devices/preamendment-status
12 See guidance entitled “Requests for Feedback on Medical Device Submissions: The Pre-Submission Program and
Meetings with Food and Drug Administration Staff” available at https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/requests-feedback-and-meetings-medical-device-submissions-q-
submission-program

15
In determining the global maximum acoustic output, manufacturers are not expected to include
hydrophone measurement uncertainties. The uncertainties of the acoustic output exposure levels
in Table 3 of Section 5.2.7 are estimated to be ±30% for intensities and ±15% for MI, so a
manufacturer may not have to account for its measurement uncertainty as long as that uncertainty
does not exceed ±30% (or ±15%). However, if the measurement uncertainty does exceed ±30%
(or ±15%), then the preamendments acoustic output exposure levels in Table 3 should be
reduced accordingly by the excess over ±30% (or ±15%).
For example, if the global maximum hydrophone-determined ISPTA.3 was 600 mW/cm2, and the
hydrophone measurement uncertainty for intensity was ±25%, then the value 600 mW/cm2 (and
not 600 x 1.25 = 750 mW/cm2) would be compared to 720 mW/cm2. However, if the
hydrophone uncertainty was ±35%, then 600 mW/cm2 would be compared to 720 x (1.30/1.35) =
693 mW/cm2. Because measurement uncertainty typically increases with increasing frequency,
this example calculation is more likely to be applicable for high frequency applications (> 20
MHz) (Nagle SM, Sundar G, Schafer ME, Harris GR, Vaezy S, Gessert JM, Howard SM, Moore
MK, Eaton RM, Challenges and regulatory considerations in the acoustic measurement of high
frequency (> 20 MHz) ultrasound, J. Ultrasound Med., 32, 1897-1911, 2013).
Manufacturers must comply with 21 CFR 820.30(j) Design History File, and it must contain or
reference the records necessary to demonstrate that the design was developed in accordance with
the approved design plan and the requirements of 21 CFR Part 820. Accordingly, you should
include documentation of the acoustic output measurement of your transducers, including
measurement instrumentation, calibration, software, test results, and test protocols.
5.2.4.1 Acoustic output test methodology: You should provide in your 510(k) either (1) a
separate section containing a description of the acoustic output test methodology or (2) a
reference to a previously cleared 510(k) submission, approved PMA, or De Novo request
that contains a description of the acoustic output test methodology (you should include a
510(k), De Novo, or PMA number, along with the attachment number and/or page
numbers). If you refer to a prior submission, any updates to the test methodology that
could affect the comparison with the predicate device should be specifically noted and
included in the submission.
The test methodology section should contain the components discussed below.
5.2.4.1.1 You should include descriptions of measurement instrumentation (e.g.,
hydrophone type, effective diameter, frequency response, hydrophone
amplifier characteristics). If you use any commercial devices, you should
include manufacturers' names and model numbers.
NOTE: We recommend that all measurements of pulsed (e.g., amplitude
modulated) waveforms that result in reported or labeled acoustic quantities
or in output display indices be made with a spot-poled membrane or
capsule hydrophone. This recommendation applies unless it can be
demonstrated that a non-membrane (e.g., needle-type) hydrophone
provides a result equivalent to or better than a membrane hydrophone,

16
whether due to the nature of the pulse or field being measured, special
hydrophone designs, or the use of correction factors or procedures, such as
deconvolution (IEC 62127-1 Ultrasonics -- Hydrophones -- Part 1:
Measurement and characterization of medical ultrasonic fields up to 40
MHz, and IEC 62127-2 Ultrasonics -- Hydrophones -- Part 2: Calibration
for ultrasonic fields up to 40 MHz). Furthermore, the combined ±3 dB
frequency response of all components used to condition, amplify, or
record the hydrophone waveform (but typically excluding the hydrophone
itself) should be documented down to at least fc/20, where fc is center
frequency. This spectral resolution is necessary to allow a full review of
the frequency response of the system. Any deviation from this practice
(e.g., due to mechanical interferences) should be described fully in this test
methodology section. Non-membrane hydrophones are appropriate for
continuous wave measurements (when reflections are a concern) and uses
not directly affecting reporting or labeling, such as in quality control
measurements.
5.2.4.1.2 You should provide a description of the measurement set-up.
5.2.4.1.3 You should include descriptions of the measurement and calculation
procedures, including consistency checks and protocol for assuring that
global maximum output conditions are identified, especially in
autoscanning and combined-mode situations. This description should
include an example calculation of the ISPTA.3 in both a non-autoscanning
and autoscanning mode, including a waveform record for the non-
autoscanning case.
NOTE: For Doppler fetal heart rate monitors (see Sections 5.2.7.1.2 and
5.2.7.2.5), the example calculation should include ISATA instead of ISPTA.3.
5.2.4.1.4 You should describe your procedures for assuring that when either
hardware or software changes are made, the effects of these changes on
the acoustic output are assessed, and if necessary, are then measured,
documented, and incorporated into the labeling and (if applicable) output
display.
5.2.4.1.5 You should describe any procedures used to correct for spatial averaging
by the hydrophone, if applicable (see Zeqiri et al., The Influence of
Waveform Distortion on Hydrophone Spatial Averaging Corrections-
Theory and Measurement, 92 J. Acoust. Soc. Am. 1809, 1809-21, 1992).
5.2.4.1.6 You should describe the calibration procedures for measurement
instruments, including how often calibrations or spot checks are
performed.

17
5.2.4.1.7 You should describe the procedures used for assessment of Type A
(random) and Type B (systematic) uncertainties associated with
measurement or calculation of the ultrasonic power, pressure, intensities,
and center frequency. In addition, you should include a brief description
of all relevant error sources considered and an explanation of how the
overall uncertainty was determined (see Appendix G, Section 2).
5.2.4.1.8 You should describe the protocol for assuring that the specifications for
acoustic output exposure levels are within the global maximum acoustic
output exposure levels specified in Sections 5.2.7 (Track 1) or 5.2.8
(Track 3). If the test protocol described in Section 5.2.4.1.3 is not used on
all devices, you should describe the correlation between acoustic output
and sensitivity or other measurable parameter(s). If 100% testing is not
performed, you should describe the statistical sampling plan used to
ensure that the specifications for acoustic output exposure levels are
meaningful. We recommend that this plan comprise the one-sided
tolerance limit for normal distributions (see Appendix B, Section (B)(5)).
This plan can be described by providing the values of g (or, equivalently,
1-a) and P. You should justify values less than g = 0.9 and P=0.9.
Note: Statistical analyses of measurement or performance data are
requested in several sections of this guidance (see Appendix G for a
summary).
5.2.5 General clinical safety and effectiveness
5.2.5.1 Clinical measurement accuracy and system sensitivity
5.2.5.1.1 You should identify and describe the various clinical (biometric)
measurements that the users may perform using the subject device.
5.2.5.1.2 For each transducer/mode combination, you should provide the accuracy
of any measurement (e.g., distance, volume, heart rate, Doppler frequency
shift, velocity, indices) that can be made in that mode and the range over
which this accuracy can be expected to be maintained. You should
describe and justify the test methodology (e.g., laboratory phantom) used
to determine each accuracy. With regard to Doppler accuracy, you should
provide a plot for each transducer of measured versus actual velocity over
the range of velocity values specified in the labeling. Simulated or
electronic data should not be used because they generally do not include
the transducer as part of the test system.
5.2.5.1.3 For each probe/mode combination in which quantitative claims regarding
Doppler sensitivity are made in the product labeling, you should provide a
minimum performance specification of the Doppler sensitivity in the
Design History File (DHF). The justification for the methodology and an

18
analysis of uncertainty should also be included in the DHF. The results of
the design validation, including identification of the design methods, the
date, and the individuals performing the validation, must be documented
in the DHF (21 CFR 820.30(g), (j)).
5.2.5.2 Thermal, mechanical, and electrical safety
Diagnostic ultrasound devices are medical electrical equipment and therefore may expose the
operator and patient to hazards associated with the use of electrical energy or may fail to operate
properly in the presence of electromagnetic disturbance.
5.2.5.2.1 Your device should be tested to demonstrate that it is thermally,
electrically, and mechanically safe, and that it performs as anticipated in
their intended use environment. We recommend that this testing be
performed as described in the currently FDA-recognized versions of the
following standards for medical electrical equipment safety and
electromagnetic compatibility:
· ANSI AAMI ES60601-1 Medical electrical equipment—Part 1:
General requirements for basic safety and essential performance.
· IEC 60601-1-2 Medical electrical equipment—Part 1-2: General
requirements for basic safety and essential performance –
Collateral standard: Electromagnetic disturbances –Requirements
and tests.
If submitting a declaration of conformity, the FDA guidance document
“Appropriate Use of Voluntary Consensus Standards in Premarket
Submissions for Medical Devices”13 provides the information on the
mechanisms of declaring the conformance to the consensus standard. For
additional information on providing electromagnetic compatibility
information in a premarket submission, please see FDA’s guidance,
“Electromagnetic Compatibility (EMC) of Medical Devices.”14
5.2.5.2.2 You should describe the means used to limit the surface heating of
invasive probes in the event of a device malfunction. You should specify
and scientifically justify your temperature limits.
5.2.5.3 Patient-contacting materials
13 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/appropriate-use-
voluntary-consensus-standards-premarket-submissions-medical-devices
14 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/electromagnetic-
compatibility-emc-medical-devices

19
5.2.5.3.1 You should provide the trade name, generic material composition (e.g.,
polyethylene, polycarbonate), and manufacturer of all patient-contact
materials or provide the Master File number that contains the material
description.
5.2.5.3.2 You should provide, for any patient contact materials, biocompatibility
evaluation of the device, conducted as described in ISO 10993-1:
Biological evaluation of medical devices –Part 1: Evaluation and testing
within a risk management process, and FDA’s guidance entitled “Use of
International Standard ISO-10993, ‘Biological Evaluation of Medical
Devices Part-1: Evaluation and Testing within a risk management
process.”15 For materials, probes, components, and accessories that have
been previously cleared for identical type and duration of contact,
biocompatibility data need not be provided if you indicate that the patient
contact materials are unchanged in formulation and processing method
from a previously cleared device.
5.2.5.4 Cleaning, disinfection, sterilization, and pyrogenicity
5.2.5.4.1 If the transducer is supplied sterile, you should provide information on the
sterilization process, according to the FDA guidance document
“Reprocessing Medical Devices in Health Care Settings: Validation
Methods and Labeling.”16 See also the guidance entitled “Submission and
Review of Sterility Information in Premarket Notification (510(k))
Submissions for Devices Labeled as Sterile.”17 We recommend the device
be sterilized with a sterility assurance level (SAL) of 10-6.
5.2.5.4.2 If the transducer is supplied non-sterile or is intended to be reprocessed
between patient use, you should provide written recommended procedures
on how to clean, disinfect, and/or sterilize the transducer between uses.
The level of disinfection or sterilization should be appropriate for the
intended clinical use. You should determine which types of disinfectants
are compatible with your products. You may recommend the use of an
FDA-cleared liquid chemical sterilant/high level disinfectant for the high
level disinfection of transducers used as semi-critical devices (see FDA’s
guidance entitled “Reprocessing Medical Devices in Health Care Settings:
Validation Methods and Labeling.”18 For sterilization, which should be
15 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/use-international-
standard-iso-10993-1-biological-evaluation-medical-devices-part-1-evaluation-and
16 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/reprocessing-medical-
devices-health-care-settings-validation-methods-and-labeling
17 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/submission-and-review-
sterility-information-premarket-notification-510k-submissions-devices-labeled
18 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/reprocessing-medical-
devices-health-care-settings-validation-methods-and-labeling

20
used for transducers in contact with the bloodstream or normally sterile
tissues, you should recommend the use of an appropriate sterilization
process, which you should validate for use with your transducers. See
Appendix E.
5.2.5.4.3 If the device is labeled non-pyrogenic, you should provide the results of
pyrogenicity testing recommended in the FDA guidance document entitled
“Submission and Review of Sterility Information in Premarket
Notification (510(k)) Submissions for Devices Labeled as Sterile.”19
5.2.5.5 Software
FDA’s guidance entitled “Guidance for the Content of Premarket Submissions for
Software Contained in Medical Devices”20 provides the recommendations for
software documentation in premarket submissions. According to this guidance
document, the level of software documentation should be based on the device’s Level
of Concern (LOC). A full description of the software/firmware supporting the
operation of the subject device, commensurate with the appropriate LOC, as defined
in the software guidance document cited above, should be provided. Please note that
changes to the device’s software must be validated and a risk analysis performed in
accordance with 21 CFR 820.30(g). You must also perform verification, review, and
approval of design changes before their implementation in accordance with 21 CFR
820.30(i). The information provided to comply with 21 CFR 820.30(g) and 21 CFR
820.30(i) must be documented in the DHF in accordance with 21 CFR 820.30(j).
When appropriate, you should provide information on the cybersecurity aspects of
your device. For more information on this topic, please see FDA’s guidance “Content
of Premarket Submissions for Management of Cybersecurity in Medical Devices.”21
If the device includes off-the-shelf software, you should provide the additional
information as recommended in the FDA documents titled “Off-the-Shelf Software
Use in Medical Devices”22 and “Cybersecurity for Networked Medical Devices
Containing Off-The-Shelf (OTS) Software,”23 which provide additional information
regarding medical devices utilizing off-the-shelf software.
19 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/submission-and-review-
sterility-information-premarket-notification-510k-submissions-devices-labeled
20 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/guidance-content-
premarket-submissions-software-contained-medical-devices
21 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/content-premarket-
submissions-management-cybersecurity-medical-devices-0
22 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/shelf-software-use-medical-
devices
23 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/cybersecurity-
networked-medical-devices-containing-shelf-ots-software

21
We recommend that your 510(k) submission also provide a summary description of new or
altered algorithms and an explanation of why they are suitable for the chosen task.
5.2.5.6 Transducer element check
Device manufacturers should implement appropriate integrated tests of transducer
performance each time a transducer is connected to the main system or activated.
The transducer performance test should be accessible by competent technical
personnel, such as operators or service personnel. While the FDA appreciates that
different performance specifications for transducers based on the application and
system configuration, each device should include some level of testing. For example,
an impedance check of each transducer element may provide a preliminary evaluation
of the element integrity and function. Device manufacturers implement methods to
communicate the results of the transducer performance tests to the operators, and
identify regions of the image that have been compromised by transducer malfunction.
This integrated test feature would also generate a report on the performance of the
probe under test for documentation, generally including listing the integrity of
elements or smallest available patches of elements. This integrated test should also
be available to the operators to initiate any time when a particular probe is suspected
of failure. As described in AIUM: Routine Quality Assurance for Diagnostic
Ultrasound Equipment, American Institute of Ultrasound in Medicine, Laurel, MD,
2008 (AIUM 2008), transducer element checks are important to ensure proper
performance of the transducer for acquiring images or signals that provide the
intended information for the users. Such proper performance is critically dependent
on the integrity of the piezoelectric transducer elements in terms of their mechanical
and electrical configuration, and the subsequent transduction function.
5.2.6 Labeling
Labeling must be sufficient to describe the device, its intended use, and the directions for its use
to satisfy the requirements of 21 CFR 807.87(e). The following information will assist you in
meeting the requirements of 21 CFR Part 801. Although final labeling is not required for 510(k)
clearance, final labeling must comply with the requirements of 21 CFR Part 801 before a medical
device is introduced into interstate commerce. In addition, final labeling for prescription medical
devices must comply with 21 CFR 801.109. Labeling recommendations in this guidance are
consistent with the requirements of 21 CFR Part 801.
5.2.6.1 You should provide draft operator's manuals and any labeling materials that describe the
system and associated transducers (maintenance manuals are not necessary). Labeling
for all prescription diagnostic ultrasound equipment must comply with 21 CFR 801.109.
In general, labeling for these devices should include:
· A description of the device;
· Indications for use;
· Contraindications;

22
· Warnings;
· Precautions;
· Adverse effects;
· Instructions for use;
· Summaries of clinical studies; and
· References.
5.2.6.1.1 You should include an indications for use statement, contraindications,
warnings, precautions, and a prescription device statement, where
appropriate. This should include:
5.2.6.1.1.1 a precaution to perform the ultrasound procedure using the
principle of ALARA (As Low As Reasonably Achievable);
5.2.6.1.1.2 for Track 1 systems (see also Table 3 of Section 5.2.7 and
Section 5.2.7.2.4), a caution (when applicable) that the
device is not intended for fetal use either in the operator's
manual, individual transducer manuals, or on equipment
labeling;
5.2.6.1.1.3 a description of the warnings, displays, or other system
responses of the device to fault conditions;
5.2.6.1.1.4 a caution that cardiac rhythm disturbances during perfusion
studies using gas ultrasound contrast agents have been
observed in the diagnostic range of Mechanical Index (MI)
values and that, for details, to see the specific package
insert for the contrast agent being used; and
5.2.6.1.1.5 appropriate data supporting specific diagnostic claims.
5.2.6.1.2 You should provide clinical instructions for the use of the device in either
the system or transducer operator's manual. Information for use must be
specified for prescription devices in accordance with 21 CFR 801.109(c).
5.2.6.1.3 You should identify the device's compatible device accessories, kits, and
components in the operator's manual(s). You should also provide the
specifications for these accessories. When use of probe sheaths is
recommended, the probe labeling should discuss the natural rubber safety
issues described in 21 CFR 801.437 User Labeling for Devices that
Contain Natural Rubber.
5.2.6.1.4 You should provide the accuracy of each clinical measurement capability
using the device and the range over which this accuracy can be expected
to be maintained.

23
NOTE: The accuracy range given for Doppler applications should not
exceed the range measured under Section 5.2.5.1.2.
5.2.6.1.5 You should provide draft acoustic output labeling in the operator's manual,
following Section 5.2.7.2 (Track 1) or Section 5.2.8.2 (Track 3).
5.2.6.1.6 You should provide instructions for care of the device between uses,
including storage, cleaning, disinfection, and sterilization of all
components, as appropriate.
5.2.6.1.6.1 For clinical applications of a semi-critical or critical nature
(e.g., intraoperative, transrectal, transvaginal,
transesophageal, or biopsy procedures), labeling should
recommend, when appropriate, the use of sterile, legally
marketed probe sheaths. Note that the use of sheaths does
not change the type of reprocessing that is recommended
after each use (see Appendix E, special situation 2).
5.2.6.1.6.2 When recommending a procedure that uses a legally
marketed liquid disinfecting or sterilizing agent, either your
labeling should reference the labeling provided by the
agent’s manufacturer or your instructions should be
consistent with the agent’s labeling.
5.2.6.1.6.3 For a reusable device, when recommending any procedure,
such as cleaning, low level disinfection, high level
disinfection, or sterilization, you should provide detailed
instructions to the user. You should validate these
procedures. Please see FDA’s guidance entitled
“Reprocessing Medical Devices in Health Care Settings:
Validation Methods and Labeling,”24 which provides
recommendations for the formulation and scientific
validation of reprocessing instructions for reusable medical
devices, as well as the recommended information you
should provide in your 510(k) submission.
5.2.6.1.7 Additional labeling may be necessary to address safety and effectiveness
concerns depending upon the clinical application(s) of the transducer (e.g.,
transcranial, transesophageal, intraoperative, transvaginal, ophthalmic, or
vascular diagnostic systems).
Neurological intraoperative probes (e.g., probes that make contact with the
24 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/reprocessing-medical-
devices-health-care-settings-validation-methods-and-labeling

24
dura matter or any intracranial tissues) should have the following
additional labeling:
5.2.6.1.7.1 a recommendation to use sterile, non-pyrogenic sheaths;
and
5.2.6.1.7.2 a caution, warning the user of the potential problem in
using the probe on patients with known or suspected
Creutzfeldt Jakob disease (CJD). The probe sheath should
not be relied upon to prevent contamination of the probe.
A transducer exposed to central nervous system tissue from
known or suspected CJD or variant CJD (vCJD) should be
destroyed since it may not be possible to sterilize it.25
5.2.6.1.8 You should provide information regarding repair of the systems and
transducers, and provide instructions to the users on repair and
maintenance of the systems and transducers, especially when they are not
functioning as designed and intended. For example, the manufacturer may
provide instructions for the users that all repair work should be performed
by the Original Equipment Manufacturer (OEM). Also, the manufacturer
may provide instructions to the users to contact the manufacturer to obtain
a list of third-party repair organizations that are qualified to repair its
transducers.
5.2.6.1.9 References to literature should be included when appropriate.
5.2.7 Track 1 recommendations
Track 1 recommendations are for diagnostic ultrasound systems that do not follow the Output
Display Standard or are not indicated for any fetal Doppler applications (except for fetal heart
rate monitors, Section 5.2.7.1.2). Track 1 submissions are evaluated in relation to
application-specific preamendments acoustic output exposure levels. Table 3 (below) lists the
highest known acoustic field emissions for preamendments diagnostic ultrasound devices. The
values are derated. Systems that exceed these application-specific acoustic output exposure
levels should be evaluated on a case-by-case basis.
Table 3: Preamendments acoustic output exposure levels
Use ISPTA.3 (mW/cm2) ISPPA.3 (W/cm2) or MI
Peripheral Vessel 720 190 1.9
25 For additional information on this topic, see “Infection Control” located at
https://www.cdc.gov/prions/cjd/infection-control.html

25
Use ISPTA.3 (mW/cm2) ISPPA.3 (W/cm2) or MI
Cardiac 430 190 1.9
Fetal Imaging &
Other26
94 190 1.9
Ophthalmic 17 28 0.23
For the purposes of acoustic output exposure levels:
· transesophageal and intravascular for non-cardiac use and musculoskeletal applications
should be included in the “Fetal Imaging & Other” category;
· cardiac use should include transthoracic adult and pediatric uses as well as intravascular
and transesophageal adult and pediatric uses for visualization of the heart and coronary
vessels; peripheral vessel use should include vessels of the neck; and
· cephalic and transcranial should be synonymous.
Note 1: Transcranial Doppler is considered to be in the “Peripheral Vessel” category unless
measurements are performed through the eye, in which case it is considered in the
“Ophthalmic” category.
5.2.7.1 Track 1 acoustic output: Track 1 is based on application-specific comparisons to
preamendments acoustic output exposure levels given in Table 3. Measurements of
acoustic output for each transducer should be made at the highest output setting
available for use.
NOTE: For each transducer, the system should operate in such a way that a conscious
and deliberate action should be necessary to change to an application or mode that has
a higher application-specific acoustic output exposure level. Otherwise, output
measurements should be made for the application having the highest application-
specific acoustic output exposure levels. (See Section 5.2.7.1.1.1).
5.2.7.1.1 Your submission should include the information described below:
5.2.7.1.1.1 For each system/transducer combination, you should
specify for each mode/application combination (as stated in
the Indications for Use), the range of values for the ISPTA.3
and for the MI or ISPPA.3 under the operating conditions that
26 The “Fetal & Other” category includes abdominal, intraoperative, pediatric, small organ (breast, thyroid, testes,
etc.), neonatal cephalic, and adult cephalic use.

26
maximize these quantities. A tabular format is desirable
(see Example 1 in Appendix F).
NOTE: The upper bound of the acoustic output values
should not be greater than the appropriate application-
specific value listed in Table 3. When system/transducer or
mode/application combinations have the same design range
for a given output quantity, a single range can be listed for
those combinations.
5.2.7.1.1.2 A description of how you intend to meet the
specification(s) in Section 5.2.7.1.1.1.
5.2.7.1.1.3 The engineering basis for the range of values specified in
Section 5.2.7.1.1.1 (e.g., preliminary or prototype
measurements, theoretical calculations, estimates based on
measurements of previously cleared transducers, or
acoustic output exposure levels).
5.2.7.1.2 For continuous-wave fetal heart rate (FHR) monitors with low-power
unfocused CW Doppler transducers, a single maximum acoustic output
exposure level for the spatial-average temporal-average intensity (ISATA) at
the transducer face of 20 mW/cm2 should be used to evaluate the acoustic
output of the device. This intensity may be estimated by dividing the
ultrasonic power by the area corresponding to the entrance beam
dimensions. A conservative approach for pulsed Doppler FHR monitors
should be to use 20 mW/cm2 as a guide for the maximum spatial-average
pulse-average intensity (ISAPA) at the transducer face. For such
transducers, two estimates should be made:
(1) duty factor (DF) = pulse duration x pulse repetition frequency
(2) ISATA @ Transducer Face = Ultrasonic Power / Area Corresponding to
entrance beam dimensions
If the ISATA @ Transducer Face / DF is less than 20 mW/cm2, then the
transducer’s acoustic output is below preamendments acoustic output
exposure levels for the type of ultrasound transducer, i.e., 20 mW/cm2. If
this value is higher than 20 mW/cm2, you should consult with the review
division about the appropriate measurements you should make.
5.2.7.1.3 Track 1 submissions for devices whose overall acoustic output exceeds
application-specific levels should be supported by laboratory and clinical
data demonstrating safety and the need for such higher output. In these
submissions, you should describe what user interactive features are
provided to enhance user awareness of acoustic output (e.g., on-screen

27
display, power up default settings, or manual override).
For example, for any transducer intended for transcranial (cephalic)
applications in which the ISPTA.3 exceeds 94 mW/cm2, you should provide
an estimate of maximum temperature rise (TR) attributable to the use of
that transducer for each operating mode. You should describe the model
used to determine the estimation. This model should account for heating
of skull bone. An example/model for making these estimates can be found
in IEC 62359. When the ISPTA.3 exceeds 94 mW/cm2 for this application,
we recommend labeling in the form of on-screen precautions about
scanning through the eye, burr-holes, fontanels, or foramen magnum.
5.2.7.2 Track 1 acoustic output labeling
5.2.7.2.1 In the operator’s manual, you should provide global maximum acoustic
output values for each possible system/transducer/mode/application
combination. A tabular format is desirable for this information. The
labeling should also include a description of any symbols used. In
addition, the labeling should include the corresponding operating
conditions, and the measurement uncertainties for acoustic quantities
(power, pressure, intensities, center frequency). The global maximum
values of MI and spatial-peak intensities in the Track 1 acoustic output
labeling should be statistical maximum values (see Appendix B, Section
(B)(5)).
5.2.7.2.2 You should provide an explanation of how derated acoustic output
exposure quantities were derived from exposure quantities measured in
water.
5.2.7.2.3 You should provide an explanation of the interactive system features that
affect acoustic output (see Section 5.2.2.1.2). You should also provide
instructions on how to use these features to follow the ALARA principle.
For transducers that exceed application-specific acoustic output exposure
levels in Table 3 of Section 5.2.7 or for transducers for which more than
one application-specific acoustic output exposure level applies, you should
describe what user-interactive features are provided to enhance user
awareness of acoustic output. For example, these features could include
an on-screen display, power-up default settings, manual override, and
warnings.
5.2.7.2.4 When abdominal Doppler is indicated, you should clearly state that this
indication does not include fetal Doppler.
5.2.7.2.5 For unfocused fetal heart rate monitors, (see Section 5.2.7.1.2), you should
provide the following information instead of that recommended in
Sections 5.2.7.2.1 and 5.2.7.2.2: ISATA at the transducer face, entrance

28
beam dimensions, center frequency, pulse duration and pulse repetition
frequency (if applicable), and measurement uncertainties for ISATA,
ultrasonic power, and center frequency. The reported ISATA at the
transducer face should be the statistical maximum of the global maximum
value (see Appendix B, Section (B)(5)).
5.2.7.3 Track 1 example acoustic output formats:
For each mode/application combination identified in Section 5.2.7.1.1.1, we recommend that you
provide the acoustic output (MI, ISPTA.3, ISPPA.3) and associated acoustic parameters and operating
control conditions. A tabular format is desirable (see Examples 2 and 3 in Appendix F for non-
autoscanning and autoscanning modes, respectively). If the acoustic output of an “other” mode
is the same (within the manufacturer’s stated measurement uncertainty) as that of a designated
standard mode, then one acoustic output description can apply for both modes. However, the
acoustic output description should be identified as applying to both modes.
All entries in Examples 2 and 3 in Appendix F should be obtained at the same operating
conditions that give rise to the global maximum derated intensity or MI value in the second row.
These operating conditions should be specified. Measurement uncertainties for acoustic
quantities (power, pressure, intensities, center frequency) should be provided.
5.2.8 Track 3 recommendations
If you follow the Output Display Standard (IEC 60601-2-37), FDA considers your device a
Track 3 device. Systems that include fetal Doppler applications, except for fetal heart rate
monitors, should follow Track 3. Under Track 3, acoustic output should not be evaluated on an
application-specific basis, but the global maximum derated ISPTA should be £ 720 mW/cm2, and
either the global maximum MI should be £ 1.9 or the global maximum derated ISPPA should be £
190 W/cm2. An exception should be for ophthalmic use, in which case, the TI = Max (TIS_as,
TIC) should be £1; ISPTA.3 £ 50 mW/cm2; and MI £ 0.23. A device with fixed acoustic output
should be Track 1, unless Section 5.2.8.1.5 applies.
5.2.8.1 Track 3 acoustic output: The Track 3 approach applies to systems that follow the Output
Display Standard. This approach eliminates the application-specific comparison of
acoustic output to preamendments acoustic output exposure levels.
5.2.8.1.1 Your submission should include the information described below:
5.2.8.1.1.1 For each system/transducer combination, we recommend
you specify for each mode (as stated in the Indications for
Use), the range of values for the ISPTA.3, and the MI or
ISPPA.3, and the range of TIs under the operating conditions
that maximize these quantities. A tabular format is
desirable; see the example given in Example 4 in Appendix
F.

29
NOTE: Where system/transducer or transducer/mode
combinations have the same design range for a given
output quantity, only a single range can be listed for those
combinations.
5.2.8.1.1.2 A description of how the specification(s) in Section
5.2.8.1.1.1 is(are) met.
5.2.8.1.1.3 The engineering basis for the range of values specified in
Section 5.2.8.1.1.1 (e.g., preliminary or prototype
measurements, theoretical calculations, estimates based on
measurements of previously cleared transducers, or
acoustic output exposure levels).
5.2.8.1.2 You should:
5.2.8.1.2.1 Indicate that the measurements made to determine the
acoustic output display indices - the TI and the MI - follow
IEC 62359; and
5.2.8.1.2.2 indicate that information supplied in the 510(k) is for
global maximum TI and MI values.
5.2.8.1.3 You should specify the default setting acoustic output exposure levels
(e.g., as a percentage of the maximum levels) and the rationale for
selecting such default values (see the clause Accidental selection of
excessive output values, IEC 60601-2-37).
NOTE: Default settings should consider the ALARA principle.
5.2.8.1.4 You should explain the reason for any TI that exceeds a value of 6.0.
5.2.8.1.5 If no system/transducer combination is capable of exceeding either a TI of
1.0 or an MI of 1.0 in any operating mode, you should submit the global
maximum values of the ISPTA.3, TI (TIS, TIB, or TIC), MI, and IPA.3 @
MImax (see Section 5.2.8.2.4). You should also include the details of the
calculations in the DHF.
5.2.8.2 Track 3 acoustic output labeling
5.2.8.2.1 In the operator’s manual, you should provide global maximum acoustic
output values for each possible system/transducer/mode combination. A
tabular format is desirable for this information; see Section 5.2.8.3. The
labeling in your 510(k) should contain the acoustic output quantities you
intend to include. The labeling also should include a description of any
symbols used. In addition, the labeling should include the corresponding

30
operating conditions, and the measurement uncertainties for acoustic
quantities (e.g., power, pressure, intensities, center frequency).
5.2.8.2.2 You should provide an explanation of the real-time display features and
controls of the system, including default settings (see the clause Accuracy
of controls and instruments and protection against hazardous outputs of
IEC 60601-2-37). You should provide instructions on how to use these
features and controls to follow the ALARA principle.
NOTE: If the intended uses include neonatal cephalic, then the provisions
of the Output Display Standard should be interpreted to mean that all three
thermal indices (TIS, TIB, TIC) should be available to be called up by the
user, although all three indices may not have to be displayed
simultaneously. In this regard, please see page 49 in the AIUM
publication, Medical Ultrasound Safety, Third Edition (AIUM 2014).
5.2.8.2.3 You should provide the display accuracy (see the clause Accuracy of
controls and instruments and protection against hazardous outputs of IEC
60601-2-37).
5.2.8.2.4 If no system/transducer combination in a Track 3 device is capable of
exceeding either a TI of 1.0 or an MI of 1.0 in any operating mode, you
should provide the mean of the global maximum values (when taken over
a number of units), for each transducer, of ISPTA.3, TI (TIS, TIB, or TIC),
MI, and IPA.3 @ MImax. See Example 5 in Appendix F. You should
explain the meaning of and describe the uncertainties associated with these
values.
5.2.8.3 Track 3 acoustic output formats:
Example 6 in Appendix F shows an example of a recommended tabular format for presenting the
transducer/mode combinations for which the global maximum displayed MI or TI is greater than
1.0. For Example 6 in Appendix F, the following mode definitions and conventions are applied:
M Mode: May include simultaneous B mode.
PW Dop./CW Dop.: In duplex modes, report largest displayed TIS
(scanned or non-scanned) if > 1.0.
Color Flow: May include simultaneous Color Flow M-mode,
B-mode and M mode. In combined modes, report
largest displayed TIS (scanned or non-scanned) if >
1.0.
Combined modes: Should only be reported as a separate mode if the
largest formulation of TIS, TIB or TIC (if there is an
applicable intended use; e.g., transcranial or

31
neonatal cephalic) is greater than the corresponding
value reported for all constituent modes.
If the acoustic output of an “other” mode is the same (within the manufacturer’s stated
measurement uncertainty) as that of a designated standard mode, then one acoustic output
description can apply for both modes. However, the acoustic output description should be
identified as applying to both modes.
For each of these transducer/mode combinations identified in Example 6 in Appendix F, we
recommend that you provide acoustic output information. This should include global maximum
index values, associated acoustic and transducer parameters, and relevant operating control
conditions. A tabular format is desirable (see the example of an Acoustic output reporting table
given in IEC 60601-2-37). All symbols used should be defined.
All values that you report should be obtained at the same operating conditions that give rise to
the global maximum Displayed Index Value. These operating conditions should be specified.
Measurement uncertainties for acoustic quantities (power, pressure, intensities, center frequency)
should also be provided.
5.2.8.4 Track 3 education program for the clinical end user
5.2.8.4.1 You should provide an ALARA education program for the clinical
end-user that covers the subjects listed below. ALARA is an acronym for
the principle of prudent use of diagnostic ultrasound by obtaining the
diagnostic information at an output that is As Low As Reasonably
Achievable. This education program should include explanations of:
5.2.8.4.1.1 The basic interaction between ultrasound and matter;
5.2.8.4.1.2 The possible biological effects;
5.2.8.4.1.3 The deviation and meaning of the indices;
5.2.8.4.1.4 A recommendation to use and follow the ALARA principle
in all studies; and
5.2.8.4.1.5 Clinical examples of specific applications of the ALARA
principle.
A document published by the AIUM (Medical Ultrasound Safety, Third Edition, American
Institute of Ultrasound in Medicine, 2014. Laurel, Maryland), includes the generic content of the
educational program. You should also provide information specific to your device regarding
ALARA.

32
5.3 Additional Considerations
The FDA Reauthorization Act (FDARA) was signed into law on August 18, 2017. Of
importance to diagnostic ultrasound devices is Section 706, entitled “Fostering Innovation in
Medical Imaging.”
Section 706 added section 520(p) to the FD&C Act and specifies that, under certain
circumstances, regulatory submissions for imaging medical devices (e.g., ultrasound imaging
systems and transducers) may include certain new uses of an approved contrast agent (imaging
drug) that are different from those described in the approved drug labeling. Such new uses of
contrast agents, which would be evaluated based on safety and effectiveness information
submitted in the device premarket application, could include, for example, different routes of
drug administration, anatomical regions, or patient populations as long as FDA determines that
the differences do not adversely affect the safety and effectiveness of the contrast agent when
used with the device. Manufacturers interested in pursuing new uses of an approved contrast
agent are strongly urged to submit a pre-submission to discuss the potential application with
FDA.27
27 See guidance entitled “Requests for Feedback on Medical Device Submissions: The Pre-Submission Program and
Meetings with Food and Drug Administration Staff” available at https://www.fda.gov/regulatory-
information/search-fda-guidance-documents/requests-feedback-and-meetings-medical-device-submissions-q-
submission-program

33
Appendix A List of Symbols Used in this Guidance
p º acoustic pressure
BW º bandwidth
A º beam cross-sectional area
P1x1 º bounded-square output power
fc º center frequency
a º derating factor
EBD º entrance beam dimensions
EDS º entrance dimensions of the scan
i º instantaneous intensity
IPA º pulse-average intensity
ISATA º spatial-average temporal-average intensity
ISPPA º spatial-peak pulse-average intensity
ISPTA º spatial-peak temporal-average intensity
ITA º temporal-average intensity
MI º mechanical index
pr º peak rarefactional pressure
Po º power, ultrasonic power
PD º pulse duration
PII º pulse intensity integral
PRF º pulse repetition frequency
S º radiating cross-sectional area
TI º thermal index

34
TIB º thermal index bone
TIC º thermal index cranium
TIS_as º soft tissue thermal index at surface
l º wavelength
The following definitions are provided for the technical terms used in this document.
acoustic pressure: The value of the total pressure minus the ambient pressure.
Symbol: p
Unit: Pascal, Pa
ALARA: As low as reasonably achievable.
autoscan (autoscanning): The electronic or mechanical steering of successive ultrasonic pulses
or series of pulses, through at least two dimensions.
bandwidth: The difference between the most widely separated frequencies f1 and f2 at which
the transmitted acoustic pressure spectrum is 71 percent (-3 dB) of its maximum value.
Symbol: BW
Unit: Hertz, Hz
beam axis: A straight line joining the points of maximum pulse intensity integral measured at
several different distances in the far field. Calculated according to regression rules, this line
extends back to the transducer assembly surface.
beam cross-sectional area: The area on the surface of a plane perpendicular to the beam axis
consisting of all points where the pulse intensity integral is greater than 25 percent of the
maximum pulse intensity integral in that plane. For situations in which the relative acoustic
pressure waveform does not change significantly across the beam cross-sectional area, the
beam cross-sectional area may be approximated by measuring the area on the surface of a plane
perpendicular to the beam axis consisting of all points where the acoustic pressure is greater
than 50 percent of the maximum acoustic pressure in the plane.
Symbol: A
Unit: centimeter squared, cm2
bounded-square output power: The maximum value of the power emitted from any one-
centimeter square region of the active area of the transducer, the one-centimeter square region
having 1 cm dimensions in the x- and y-directions. See the definition of bounded power, and the
Schematic diagram of the different planes and lines in an ultrasonic field in IEC 62359.
Symbol: P1x1

35
Unit: watt, W
center frequency: Defined as
fc = (f1 + f2)/2
where
f1 and f2 are frequencies defined in bandwidth.
Symbol: fc
Unit: Hertz, Hz
declaration of conformity: A document that declares that a product is in conformance with the
provisions of a recognized standard pursuant to Section 514(c) of the FD&C Act. Information
on such declarations is available in FDA’s guidance entitled “Appropriate Use of Voluntary
Consensus Standards in Premarket Submissions for Medical Devices.”28
derated peak rarefactional pressure: The value of pr derated by 0.3 dB cm-1 MHz-1 to account
for the acoustic attenuation in soft tissues.
Symbol: pr.3
Unit: megapascal, MPa
derating (derating factor, derated): A factor applied to acoustic output parameters intended to
account for ultrasonic attenuation of tissue between the source and a particular location in the
tissue. As referred to in this document, the average ultrasonic attenuation is assumed to be a 0.3
dBcm-1MHz-1 along the beam axis in the body. Derated parameters are denoted with a
subscript “.3”.
Symbol: a
Unit: decibel per centimeter - megahertz, dB cm-1MHz-1
design history file (DHF): Documentation established and maintained by the manufacturer for
each type of medical device. The design history file must contain or reference the records
necessary to demonstrate that the design was developed in accordance with the approved design
plan and the requirements of 21 CFR Part 820. See 21 CFR 820.30(j).
designated standard mode: Consists of the following specific operating modes: A-mode, B-
mode, M-mode, PW Doppler, CW Doppler, and Color Doppler.
duty factor: The product of the pulse duration and the pulse repetition frequency for a pulsed
waveform.
entrance beam dimensions: The dimensions of the –12 dB beam width where the beam enters
the patient. For contact transducers, these dimensions can be taken as the dimensions of the
radiating element if so stated.
28 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/appropriate-use-
voluntary-consensus-standards-premarket-submissions-medical-devices.

36
Symbol: EBD
Unit: centimeter, cm
entrance dimensions of the scan: For autoscan systems, the dimensions of the area of the
surface through which the scanned ultrasound beams enter the patient, consisting of all points
located within the -12 dB beam width of any beam passing through that surface during the scan.
Symbol: EDS
Unit: centimeter, cm
envelope: A smooth curve tangent to and connecting the peaks of successive cycles of a
waveform.
far field: That region of the field in which the acoustic energy flow proceeds essentially as
though coming from a point source located in the vicinity of the transducer assembly. (For an
unfocused transducer assembly, the far field is commonly at a distance greater than S/
pl
where S is the radiating cross-sectional area and l is the acoustic wavelength in the medium.)
focal surface: The surface which contains the smallest of all beam cross-sectional areas of a
focusing transducer assembly.
Symbol: (none)
Unit: centimeter squared, cm2
global maximum: The greatest value of a quantity evaluated over all times, over all locations,
and overall operating conditions for any given operating mode.
intensity: The ultrasonic power transmitted in the direction of acoustic wave propagation, per
unit area normal to this direction, at the point considered. For measurement purposes, this point
is restricted to points where it is reasonable to assume that the acoustic pressure and particle
velocity are in phase, viz., in the far field or the area near the focal surface.
intensity, instantaneous: The instantaneous ultrasonic power transmitted in the
direction of acoustic wave propagation, per unit area normal to this direction, at the point
considered. It is given in the far field by:
i = p2/
rc
where
p is the instantaneous acoustic pressure;
r is the density of the medium; and
c is the speed of sound in the medium.
Symbol: i
Unit: Watt per square-centimeter, W cm-2
intensity, pulse-average: The ratio of the pulse intensity integral (energy fluence per
pulse) to the pulse duration.
Symbol: IPA
Unit: Watt per square-centimeter, W cm-2

37
intensity, spatial-average temporal-average: For autoscanning systems, the
temporal-average intensity averaged over the scan cross-sectional area on a surface
specified (may be approximated as the ratio of ultrasonic power to the scan cross-
sectional area or as the mean value of that ratio if it is not the same for each scan); for
non-autoscanning systems, the temporal-average intensity averaged over the beam
cross-sectional area (may be approximated as the ratio of ultrasonic power to the beam
cross-sectional area).
Symbol: ISATA
Unit: milliwatt per square-centimeter, mW cm-2
intensity, spatial-peak pulse-average: The value of the pulse-average intensity at the
point in the acoustic field where the pulse-average intensity is a maximum or is a local
maximum within a specified region.
Symbol: ISPPA
Unit: Watt per square-centimeter, W cm-2
intensity, derated spatial-peak pulse-average: The value of ISPPA derated by 0.3 dB
cm-1 MHz-1 to account for the acoustic attenuation in soft tissues.
Symbol: ISPPA.3
Unit: milliwatt per square-centimeter, W cm-2
intensity, spatial-peak temporal-average: The value of the temporal-average
intensity at the point in the acoustic field where the temporal-average intensity is a
maximum, or is a local maximum within a specified region.
Symbol: ISPTA
Units: milliwatts per square-centimeter, mW cm-2
intensity, derated spatial-peak temporal-average intensity: The value of ISPTA derated
by 0.3 dB cm-1 MHz-1 to account for the acoustic attenuation in soft tissues.
Symbol: ISPTA.3
Unit: milliwatt per square-centimeter, mW cm-2
intensity, temporal-average: The time average of intensity at a point in space. For non-
autoscan systems, the average is taken over one or more pulse repetition periods. For
autoscan systems, the intensity is averaged over one or more scan repetition periods
for a specified operating mode. For autoscan modes, the average includes contributions
from adjacent lines that overlap the point of measurement. For combined modes the
average includes overlapping lines, from all constituent discrete operating mode signals.
Symbol: ITA
Unit: milliwatt per square-centimeter, mW cm-2

38
invasive probe: An ultrasound probe that is intended to contact tissue other than intact skin or
the surface of the eye. These include transvaginal, transesophageal, transrectal, transurethral,
intravascular, and intraoperative probes.
mechanical index (MI): The spatial-peak value of the peak rarefactional pressure, derated
by 0.3 dB/cm-MHz at each point along the beam axis, divided by the square root of the center
frequency, that is:
( 	)2	1
3. 	)	( 	c	sp	r 	f	z	p	MI 	=
where
pr.3 (zsp) is the peak rarefactional pressure in megapascals derated by 0.3 dB/cm-MHz
to the point on the beam axis, zsp, where the pulse intensity integral (PII.3) is maximum;
and
fc is the center frequency in megahertz.
Symbol: MI
Unit: Unitless
mode: One of the following system operations: A-mode, M-mode, static B-mode, real-time B-
mode, CW Doppler, pulse Doppler, static flow mapping, real-time flow mapping, or any other
single display format for presenting clinical information.
non-autoscan (non-autoscanning): The emission of ultrasonic pulses in a single direction,
where scanning in more than one direction would necessitate moving the transducer manually.
operating condition: Any one combination of the possible particular output control settings
for a mode.
output control settings: The settings of the controls affecting the acoustic output of an
ultrasound instrument. Such controls may include, but are not limited to, the power output
control, the focal zone control, and the imaging range control.
Output Display Standard: IEC 60601-2-37 “Medical electrical equipment - Part 2-37:
Particular requirements for the safety of ultrasonic medical diagnostic and monitoring
equipment,” (IEC 60601-2-37).
peak rarefactional pressure; peak negative pressure: Maximum of the modulus of the
negative instantaneous acoustic pressure in an acoustic field during an acoustic repetition
period.
Symbol: pr or p-
Unit: megapascal, MPa
power (ultrasonic power): A quantity describing the rate at which acoustic energy travels per
unit time in the direction of propagation. Unless stated otherwise, all references to power
measurements in this guidance will be to temporal-average values. For the operating condition

39
giving rise to ISPTA.3, Po is the total time-average power; for the operating condition subject to
reporting under ISPPA.3, Po is the ultrasonic power associated with the transmit pattern giving
rise to the value reported under ISPPA.3.
Symbol: Po
Units: Watts, W
pressure: See acoustic pressure.
pulse-average intensity: See intensity.
Symbol: IPA
Unit: Watt per square-centimeter, W cm-2
pulse duration: 1.25 times the interval between the time when the time integral of intensity in
an acoustic pulse at a point reaches 10 percent and when it reaches 90 percent of the pulse
intensity integral.
Symbol: PD
Unit: second, s
pulse intensity integral: The time integral of instantaneous intensity, for any specific point
and pulse, integrated over the time in which the envelope of acoustic pressure or hydrophone
signal for the specific pulse is nonzero. It is equal to the energy fluence per pulse. For a
transducer assembly operating in a non-autoscanning mode, it is equal to the product of
temporal-average intensity and pulse repetition period.
Symbol: PII
Unit: Joule per centimeter-squared, J cm-2
pulse repetition frequency: For a pulsed waveform, the number of pulses generated per second.
Symbol: PRF
Unit: Hertz, Hz
radiating cross-sectional area: The area of the surface at and parallel to the face of the active
transducer element(s) and consisting of all points where the acoustic pressure is greater than
minus 12 dB of the maximum acoustic pressure in that surface. The area of the active
element(s) of the transducer assembly may be taken as an approximation for the radiating
cross-sectional area.
Symbol: S
Unit: centimeter squared, cm2
scan cross-sectional area: For auto-scanning systems, the area, on the surface considered,
consisting of all points located within the beam cross-sectional area of any beam passing
through the surface during the scan.
Symbol: (none)
Unit: centimeter squared, cm2
spatial-average temporal-average intensity: See intensity.

40
Symbol: ISATA
Unit: milliwatt per square-centimeter, mW cm-2
spatial-peak pulse-average intensity: See intensity.
Symbol: ISPPA
Unit: Watt per square-centimeter, W cm-2
spatial-peak temporal-average intensity: See intensity.
Symbol: ISPTA
Unit: milliwatt per square-centimeter, mW cm-2
temporal-average intensity: See intensity.
Symbol: ITA
Unit: milliwatt per square-centimeter, mW cm-2
thermal index (TI): A quantity related to calculated or estimated temperature rise under certain
defined assumptions. The thermal index is the ratio of total acoustic power to the acoustic
power required to raise tissue temperature by 1ºC under defined assumptions. In the calculation
of all thermal indices in the Output Display Standard, the average ultrasonic attenuation is
assumed to be 0.3 dB/cm-MHz along the beam axis in the body. (See Tables 1, 2, A.1, and A.2
in IEC 62359 for thermal index categories, models, and formulae.)
Symbol: TI
Unit: Unitless
TISas: The soft-tissue thermal index at surface for non-autoscanning mode:
210
1	1 	c	x
as
f	P
TIS 	=
210
1	1 	c	x
as
f	P
TIS 	=
where
P1x1 is the bounded-square output power in milliwatts;
fc is the center frequency in megahertz.
Symbol: TISas
Unit: Unitless
transducer assembly: The transducer(s), the transducer housing (probe), any associated
electronic circuitry, any liquids contained in the housing, and the integral cable, which connects
the transducer probe to an ultrasound console.
ultrasonic power: See power.
waveform: The graphical characterization of an acoustical or electrical parameter as a function
of time.

41
waveform record: A permanent plot or photograph of a voltage waveform for a specific
hydrophone when excited under specified conditions.
wavelength: The ratio of the speed of sound in the medium to the center frequency.
Symbol:
l
Unit: centimeters per cycle, cm cycle-1

42
Appendix B Format and Content of Acoustic Output
Measurement and Labeling Records Maintained in the
Design History File
General Information
This appendix is intended to assist manufacturers in documenting the final measurement data and
product labeling information, based on their production devices. This information should be
maintained in the Design History File (DHF).
Recommended records:
A. LABELING/USER INFORMATION
The DHF should contain:
1. a copy of all labeling, including acoustic output information following Sections 5.2.7.2 and
5.2.8.2 of this guidance; and
2. the global maximum derated ISPTA intensity values and Mechanical Index (or derated ISPPA
intensity) values obtained from production units as determined according to Section B.5
below. For Track 1, you should document this information for each
system/transducer/mode/application combination (i.e., one set of values for each applicable
mode/application combination identified under Section 5.2.7.1.1.1 of this guidance). For
Track 3, you should document this information for each system/transducer/mode
combination (i.e., one set of values for each applicable mode identified under Section
5.2.8.1.1.1 of this guidance).
B. GMP TEST PLAN
The DHF should contain:
1. The number of units tested and percentage of production lot, if applicable;
2. Measurement uncertainties for acoustic quantities (power, pressure, intensities, and center
frequency);
3. The operating conditions used to obtain the measured acoustic output;
4. A statement explaining whether the operating conditions result in maximizing output, and
if not, a justification for equivalence; and
5. The statistical plan and protocol used to ensure that the appropriate intensity and index
values are not exceeded [ISPTA.3 values for Track 1 (see Table 3 of Section 5.2.7); ISPTA.3 =
720 mW/cm2 (50 for ophthalmic) for Track 3; for Track 3 ophthalmic, Max(TIS_as,
TIC)£1; MI = 1.9 (0.23 for ophthalmic) for both tracks; ISATA or ISAPA = 20 mW/cm2 for
Doppler FHR monitors (see Section 5.2.7.1.2)].

43
If 100 percent sampling is not done, then the sampling plan should provide reasonable
statistical assurance that production units will not exceed the maximum acoustic output
exposure levels specified in Sections 5.2.7 (Track 1) and 5.2.8 (Track 3) of this guidance.
We recommend that the statistical technique known as “one-sided tolerance for normal
distributions” be used. See Hahn et al. 1991, Section 2.4 (pages 34-36), Sections 4.6.3 and
4.6.4 (pages 60-61), and Table A.12d (page 315), or see Natrella MG: Experimental
Statistics, NBS Handbook 91, National Institute of Standards and Technology,
Gaithersburg MD, 1966, Section 2-5 (page 2-13) and Table A-7 (page T-14). This
procedure has the following formulation:
L ³ X + Ks
where:
L is the relevant ISPTA.3 or MI (or ISPPA.3) preamendments acoustic output exposure level
(see Table 3 in Section 5.2.7);
X is the mean of the measured values;
s is the standard deviation of the measured values; and
K is the tolerance coefficient and is a function of the confidence level (notated (1 - a) in
Hahn et al. 1991 and g in Natrella 1966), the proportion (P) of the distribution less
than (X + Ks), and the sample size (n).
The choices for g (or, equivalently, 1 - a), P, and n are at the manufacturer's discretion.
However, the choices for g, P, and n should be documented and justified in the GMP
process and the DHF. The values of X and s also should be documented.
For this statistical procedure to be valid, the sample size n should not be less than three.
Also, please note that, if the above one-sided tolerance inequality is not met for an initial
(and presumably low) sample size, you should not simply increase n to achieve a lower
tolerance coefficient value (K) and continue the test.
An example of applying this procedure to a population of ultrasound transducers is given in
Ziskin MC: Measurement of uncertainty in ultrasonic exposimetry, Ultrasonic
Exposimetry, M.C. Ziskin and P.A. Lewin, eds. (CRC Press, Boca Raton, FL) pp. 409 443,
1993and Ziskin MC: Specification of acoustic output level and measurement uncertainty in
ultrasound exposimetry, IEEE Trans. Ultrasonics, Ferroelectrics, and Frequency Control,
50, 1023-34, 2003. However, please note that Table 2 in Ziskin 1993 is incorrect and
should be replaced by either Table A-7 in Natrella 1966, Table A.12d in Hahn et al. 1991,
or Table II in Ziskin 2003.
NOTE: In computing the standard deviation s, the hydrophone measurement uncertainty
should not be taken into account if it is less than ±30% for intensity or ±15% for MI.
However, if the hydrophone measurement uncertainty exceeds these values, then the
acoustic output exposure levels in Section 5.2.7 (Track 1) or Section 5.2.8 (Track 3) should
be reduced accordingly as described in Section 5.2.4, paragraph 4.
C. STATISTICAL TECHNIQUES

44
For ongoing testing of production units, statistical techniques must conform to 21 CFR 820.250.

45
Appendix C Non-OEM Replacement Transducers and
Remanufactured Transducers
Non-original equipment manufacturer (OEM) replacement transducers are generally those that
are manufactured by a party other than the OEM and are intended to replace a transducer
originally provided by the system manufacturer. Transducers may be remanufactured by the
OEM, or entities other than the OEM. FDA considers transducers that are processed,
conditioned, renovated, repackaged, restored, or subjected to any modification that significantly
changes its performance or safety specifications, or intended use to be remanufactured.29
Examples of actions that could be considered remanufacturing are changing the acoustic stack,
electrical component, or patient-contact material.
Like new OEM transducers, non-OEM replacement transducers and remanufactured transducers
are new medical devices. As such, they are subject to the 510(k) premarket notification
regulations (21 CFR 807.81). They are required to have a cleared 510(k) prior to being
marketed.
In addition to the information recommended in the body of this guidance, we recommend the
following in regard to acoustic output testing, biocompatibility testing, and labeling for
diagnostic ultrasound replacement transducers:
1. In making the acoustic output comparison between the replacement and the OEM
transducers, three or more transducers of each type should be used. The use of a single OEM
generator may be appropriate if it operates within the OEM’s specifications.
2. Acoustic output comparisons in the basic modes of M, B, and pulsed Doppler may be
appropriate, but worst-case (i.e., maximum output) conditions should be identified and
reported.
3. New acoustic output information (see Sections 5.2.7.2 and 5.2.8.2) should be provided in the
transducer operator’s manual whether or not you can demonstrate that the acoustic outputs of
the replacement or remanufactured and OEM transducers agree within the limits of the
measurement uncertainty. Moreover, if the outputs do not agree, the manufacturer should
demonstrate that means have been incorporated into the replacement transducer to ensure the
accuracy of the acoustic output real-time display indices, as well as the accuracy of any
clinical measurement performed using the transducer. Furthermore, if the outputs do not
agree, then the transducers should not be referred to as "replacement." Instead, the
transducers should be referred to as "similar to" and the differences should be noted.
4. The acoustic output measurement methodology should be completely described following
Section 5.2.4.1 of this guidance.
29 21 CFR 820.3(w).

46
All patient contact materials that are changed during the remanufacturing process should be
tested for biocompatibility (see Section 5.2.5.3).

47
Appendix D Reprocessed “Single-Use Only” Transducers
Reprocessed single-use only transducers are ultrasound transducers that are intended by the
OEM to be single-use devices (SUDs), but after such single-use they are reprocessed for use on
another patient or in another procedure on the same patient. Reprocessing of SUDs requires a
registered reprocessor to submit a 510(k) to the FDA for premarket clearance under 21 CFR
807.81. See FDA’s guidances entitled “Frequently-Asked-Questions about the Reprocessing and
Reuse of Single-Use Devices by Third-Party and Hospital Reprocessors”30 and “Frequently-
Asked-Questions about the Reprocessing and Reuse of Single-Use Devices by Third-Party and
Hospital Reprocessors - Three Additional Questions.”31 The reprocessor should conduct
functional testing, as well as validation of cleaning and sterilization. For the 510(k) submission,
reprocessors should address the following points in addition to providing the other information
recommended in the body of this guidance.
1. You should provide a detailed discussion of how you confirm that the diagnostic
ultrasound performance characteristics (e.g., image quality, acoustic output) and physical
integrity of the reprocessed transducer (when used with each compatible OEM system)
are substantially equivalent to the original OEM device following transducer reprocessing
for the maximum recommended number of cycles.
2. You should describe the acoustic output test methodology following Section 5.2.4.1 of
this guidance. You should furnish final acoustic output test results for the last
recommended reprocessing cycle. You should compare these results to those for the
OEM device. We recommend that you measure three or more reprocessed OEM
transducers for this comparison.
3. You should describe the testing to be performed to verify that the repeated reprocessing
procedures are not adversely affecting the acoustic output and imaging performance of
the transducer, as recommended in the guidance entitled “Medical Device User Fee and
Modernization Act of 2002, Validation Data in Premarket Notification Submissions
(510(k)s) for Reprocessed Single-Use Medical Devices”32 (Validation Data guidance).
4. If the maximum number of reprocessing cycles for the transducer is not specified by the
OEM, then you should test each transducer (100% sampling) for acoustic performance
characteristics following each reprocessing cycle. All results should be documented and
compared to the original OEM device specifications.
30 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/frequently-asked-
questions-about-reprocessing-and-reuse-single-use-devices-third-party-and-hospital
31 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/frequently-asked-
questions-about-reprocessing-and-reuse-single-use-devices-third-party-and-hospital-0
32 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/medical-device-user-
fee-and-modernization-act-2002-validation-data-premarket-notification

48
5. You should describe the method that you as the reprocessor use to keep track of the
number of reprocessing cycles that an individual transducer has undergone. This can be
addressed by referring to the Validation Data guidance.

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Appendix E Cleaning, Disinfection, and Sterilization
Reusable devices should contain clear instructions for cleaning and for disinfection and/or
sterilization. The recommended cleaning, disinfection, and sterilization procedures should be
validated by the probe manufacturer. Guidance on providing label reprocessing instructions and
conducting reprocessing validation testing can be found in the guidance entitled “Reprocessing
Medical Devices in Health Care Settings: Validation Methods and Labeling.”33
According to the FDA guidance document cited above, ultrasound probes that are non-critical
devices should be cleaned and undergo low-level disinfection between patient uses. Probes used
in semi-critical applications should undergo sterilization between uses whenever feasible, but
high-level disinfection is minimally acceptable. In addition, the use of a sterile sheath is
recommended for every semi-critical use of the probe. Critical devices should be sterilized, and
the use of a sterile sheath is recommended for each use. Please note that the use of sheaths does
not change the type of processing that is recommended for the transducer. After use, the single-
use sheath should be removed and discarded. The probe used in a semi-critical application
should be cleaned and undergo sterilization or at least receive high level disinfection after use
even if a sheath was used. Probes used for critical applications should be cleaned and undergo
sterilization after use even if a sterile sheath was used. Sheaths can fail during use and the level
of resulting contamination may not be easily visible.
In addition, there are several special situations:
1. Neurosurgical use: Probes that contact brain tissue and cerebrospinal fluid should be used
with a single-use, sterile, non-pyrogenic sheath because any disinfectant/sterilant residue
left on the probe may be neurotoxic and any residual endotoxin is pyrogenic (i.e., causes
fevers). NOTE: If the probe is used on a patient with known or suspected Creutzfeldt-
Jakob Disease (CJD), the probe should be destroyed. For more information on CJD and
infection control, see https://www.cdc.gov/prions/cjd/infection-control.html.34
2. Endoscopic, rectal, and transvaginal probes should be used with a single-use sterile
sheath. If these probes are used to assist biopsy procedures, all of the biopsy accessories
should be sterile for the procedure and any reusable biopsy accessories should be
reprocessed after each use. If the transducer probe itself has a built-in channel for the
needle guide, that channel could create a risk for contamination of the biopsy needle
during use unless the channel is thoroughly cleaned and the probe is sterilized before use
on another patient.
33 Available at https://www.fda.gov/regulatory-information/search-fda-guidance-documents/reprocessing-medical-
devices-health-care-settings-validation-methods-and-labeling
34 For additional information on this topic, see “Infection Control” located at
https://www.cdc.gov/prions/cjd/infection-control.html

50
3. Due to the inherent limitations of using liquid chemicals for sterilizing medical devices,
liquid chemical sterilization should be limited to only critical and semi-critical devices
that are heat-sensitive and incompatible with other sterilization methods.

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Appendix F Acoustic Output Reporting Examples
Example 1
TRACK 1 SUMMARY
System: ______________ Transducer: ______________
Mode of Operation
Clinical
Application
Global Maximum
Output Level (est.)
B M PWD CWD Color
Doppler
Combined
(Specify)
Other*
(Specify)
max ISPTA.3
Ophthalmic min ISPTA.3
max MI (or ISPPA.3)
min MI (or ISPPA.3)
max ISPTA.3
Fetal
Imaging min ISPTA.3
& Other max MI (or ISPPA.3)

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*Examples of other modes of operation include: A-mode, Amplitude Doppler, 3-D Imaging, Harmonic Imaging, Tissue Motion
Doppler, and Color Velocity Imaging
N.B. The information should be provided separately for each system and transducer.
min MI (or ISPPA.3)
max ISPTA.3
Cardiac min ISPTA.3
max MI (or ISPPA.3)
min MI (or ISPPA.3)
max ISPTA.3
Peripheral min ISPTA.3
Vessel max MI (or ISPPA.3)
min MI (or ISPPA.3)

53
Example 2
Acoustic Output Format for Track 1
Non-Autoscanning Mode
System: Operating Mode:
Transducer Model: Application(s):
Acoustic Output MI ISPTA.3
(mW/cm2)
ISPPA.3
(W/cm2)
Global Maximum Value
pr.3 (MPa)
Po (mW)
Associated fc (MHz)
Acoustic zspNote 1 (cm)
Parameter Beam dimensions x-6 Note 2
(cm)
y-6 Note 2
(cm)
PD (μsec)
PRF (Hz)
EBD Az.
(cm)

54
Ele.
(cm)
Operating Control 1
Control Control 2
Conditions Control 3
••• ••• ••• •••
Note 1: zsp is the axial distance at which the reported parameter is measured in centimeters.
Note 2: x-6, y-6, respectively, the in-plane (azimuthal) and out-of-plane (elevational) -6 dB
dimensions in the x-y plane where zsp is found in centimeters.

55
Example 3
Acoustic Output Format for Track 1
Autoscanning Mode
System: Operating Mode:
Transducer Model: Application(s):
Acoustic Output MI ISPTA.3
(mW/cm2)
ISPPA.3
(W/cm2)
Global Maximum Value
pr.3 (MPa)
Po (mW)
Associated fc (MHz)
Acoustic zspNote 1 (cm)
Parameter Beam dimensions x-6Note 2
(cm)
y-6Note 2
(cm)
PD (μsec)
PRF (Hz)
EDS Az.
(cm)

56
Ele.
(cm)
Operating Control 1
Control Control 2
Conditions Control 3
••• ••• ••• •••
Note 1: zsp is the axial distance at which the reported parameter is measured in centimeters.
Note 2: x-6, y-6, respectively, the in-plane (azimuthal) and out-of-plane (elevational) -6 dB
dimensions in the x-y plane where zsp is found in centimeters

57
Example 4
Track 3 Output Range Summary Format
System: _________________
Transducer: _________________
Mode of Operation
Global Maximum
Output Levels (est.)
B M PWD CWD Color
Doppler
Combined
(Specify)
Other*
(Specify
)
max ISPTA.3
min I SPTA.3
max MI (or
I SPPA.3)
min MI (or
I SPPA.3)
max TIS
min TIS
max TIB
min TIB
max TIC
min TIC
* Examples of other modes of operation may include: A-mode, Amplitude Doppler, 3-D
Imaging, Harmonic Imaging, Tissue Motion Doppler, and Color Velocity Imaging
N.B. The information should be provided separately for each system and transducer.

58
Example 5
TRACK 3 SUMMARY
(for systems with no probes having global maximum index values exceeding 1.0)
System: _________________
Transducer
Model
ISPTA.3 TI Type TI Value MI IPA.3@MImax
Model A
Model B
Model C
••• ••• ••• ••• ••• •••

59
Example 6
Track 3 Transducer/Mode Combination Summary Format
System: _________________
Mode of Operation
Transducer
Model
B M PWD CWD Color
Doppler
Combined
(Specify)
Other*
(Specify)
*Examples may include: A-mode, Amplitude Doppler, 3-D Imaging, Harmonic Imaging, Tissue
Motion Doppler, Color Velocity Imaging
In Example 3-3, the following mode definitions and conventions apply:
M Mode: May include simultaneous B mode.
PW Dop./CW Dop.: In duplex modes, report largest displayed TIS (scanned or
non-scanned) if > 1.0.
Color Flow: May include simultaneous Color Flow M-mode, B-mode and M
mode. In combined modes, report largest displayed TIS (scanned
or non-scanned) if > 1.0.
Combined modes: Should only be reported as a separate mode if the largest
formulation of TIS, TIB or TIC (if there is an applicable intended

60
use; e.g., transcranial or neonatal cephalic) is greater than the
corresponding value reported for all constituent modes.

61
Appendix G Statistical Analyses
There are four areas of the submission in which a statistical analysis of measurement or
performance data should be conducted and provided.
1. Description of clinical measurement accuracy (see Sections 5.2.5.1.2 and 5.2.6.1.4).
2. Description of measurement uncertainties for acoustic quantities (power, pressure,
intensities, center frequency) (see Section 5.2.7.2.4 (Track 1) and Section 5.2.8.2.1
(Track 3)). In this regard, a good description of the various potential sources of Type A
(random) and Type B (systematic) uncertainties for hydrophone measurements can be
found in Preston RC, Bacon DR, Smith RA: Calibration of medical ultrasonic equipment
procedures and accuracy assessment, IEEE Trans. Ultrasonics, Ferroelectrics, and
Frequency Control, 35, 110 121, 1988 (see also Ziskin 2003).
3. Description of statistical sampling plan used to ensure that the specifications for acoustic
output exposure levels are meaningful (see Section 5.2.4.1.8 and Ziskin 2003).
4. Description of display accuracy, as specified in the clause Accuracy of controls and
instruments and protection against hazardous outputs of IEC 60601-2-37 (see Section
5.2.8.2.3).