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YY/T 0937-2022: PDF in English (YYT 0937-2022) YY/T 0937-2022
YY
PHARMACEUTICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 17.140.50
CCS C 41
Replacing YY/T 0937-2014
Technical Requirements for Ultrasonically Tissue-mimicking
Phantom
ISSUED ON: MAY 18, 2022
IMPLEMENTED ON: JUNE 1, 2023
Issued by: National Medical Products Administration
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative References ... 4
3 Terms and Definitions ... 4
4 Technical Requirements for Tissue-mimicking Phantom ... 7
5 Accompanying Documentation of Tissue-mimicking Phantom ... 9
6 Measurement Methods for Technical Parameters of Tissue-mimicking Phantom ... 9
7 Evaluation of Tissue-mimicking Phantom ... 10
Appendix A (informative) Description of Two Measurement Methods for Detection
Depth of Type-B Ultrasonic Imaging ... 11
Appendix B (informative) Description of Technical Requirements for TM Material and
Target Line ... 13
Appendix C (normative) Evaluation of Tissue-mimicking Phantom ... 17
Bibliography ... 19
Technical Requirements for Ultrasonically Tissue-mimicking
Phantom
1 Scope
This document specifies the technical requirements, accompanying documentation,
measurement methods and evaluation of ultrasonically tissue-mimicking phantom.
This document is applicable to ultrasonically tissue-mimicking phantom.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
GB/T 4472 Determination of Density and Relative Density for Chemical Products
GB 10152-2009 B Mode Ultrasonic Diagnostic Equipment
GB/T 15261 Measurement Methods for Acoustic Properties of Ultrasonically Tissue-
mimicking Materials
YY/T 0703-2008 Ultrasonics - Real-time Pulse-echo Systems - Test Procedures to Determine
Performance Specifications
3 Terms and Definitions
What is defined in GB 10152-2009 and YY/T 0703-2008, and the following terms and
definitions are applicable to this document.
3.1 Ultrasonically Tissue-mimicking Phantom; Ultrasound Tissue Phantom
Ultrasonically tissue-mimicking phantom refers to Type-B ultrasonic imaging performance
detection device composed of ultrasonically tissue-mimicking material and one or more groups
of targets embedded in it.
[source: GB 10152-2009, 3.8, modified]
3.2 Ultrasonically Tissue-mimicking Material
Ultrasonically tissue-mimicking material refers to a material whose sound velocity, attenuation
3.8 Target Group for Axial Resolution
Target group for axial resolution refers to several groups of nylon line targets successively
arranged along the curve or oblique line at the specified depth of the ultrasonic phantom, with
different longitudinal spacing, and are used to detect the axial resolution of Type-B ultrasonic
imaging.
3.9 Target Group for Lateral Resolution
Target group for lateral resolution refers to several groups of nylon line targets successively
arranged along the lateral straight line at the specified depth of the ultrasonic phantom, with
different transverse spacing, and are used to detect the lateral resolution of Type-B ultrasonic
imaging.
3.10 Multi-purpose Phantom
Multi-purpose phantom refers to an ultrasonically tissue-mimicking phantom composed of the
background TM material and multiple line target groups embedded in it (usually including
target group for dead zone, longitudinal linear target group, transverse linear target group, target
group for axial resolution and target group for lateral resolution, etc.) and targets mimicking
cysts, tumors, stones and other lesions, and used to detect most of the performance parameters,
such as: dead zone, detection depth, axial / lateral resolution, and longitudinal / transverse
geometric measurement error of low-frequency (usually below 5 MHz) Type-B ultrasonic
imaging device, and can also examine the characteristics, such as: image uniformity and
imaging of typical lesions, etc.
3.11 Small Part Phantom
Small part phantom refers to an ultrasonically tissue-mimicking phantom composed of the
background TM material and multiple line target groups embedded in it (usually including
target group for dead zone, longitudinal linear target group, transverse linear target group, target
group for axial resolution and target group for lateral resolution, etc.) and targets mimicking
cysts, tumors and other lesions, and used to detect the dead zone, detection depth, axial / lateral
resolution, and longitudinal / transverse geometric error of high-frequency (usually 5 MHz and
above) Type-B ultrasonic imaging device, and can also examine the characteristics, such as:
image uniformity and imaging of typical lesions, etc.
NOTE: due to the superficial position of the diagnostic object of the corresponding Type-B
ultrasonic imaging device, the high-frequency probe has a higher spatial resolution and a
lower detection depth. The basic characteristics of the small part phantom that are different
from the multi-purpose phantom are: relatively small overall size, lesion-mimicking size
and target line spacing of target group for resolution, and the uppermost target line and
lesion-mimicking position in the target group for dead zone that are closer to the acoustic
window.
3.12 Slice Thickness Phantom
Slice thickness phantom refers to an ultrasonically tissue-mimicking phantom composed of the
background TM material and the scattering layer with or without the back plate embedded in it
and (or) the longitudinal line target group, and specifically used to detect the slice thickness
parameter of the sound beam of Type-B ultrasonic imaging device.
3.13 Three-dimensional (3D) Phantom
Three-dimensional phantom refers to an ultrasonically tissue-mimicking phantom composed of
the background TM material and the oval target embedded in it, and specifically used to detect
the volume measurement errors in three-dimensional imaging.
NOTE: generally speaking, the background TM material has similar acoustic attenuation properties
to the target, but significantly different backscattering.
3.14 Contrast Resolution Phantom
Contrast resolution phantom refers to an ultrasonically tissue-mimicking phantom composed of
the background TM material, and cylindrical, conical or pagoda-shaped target embedded in it,
whose backscattering is higher and lower than the background, and used to detect the contrast
resolution parameter of Type-B ultrasonic imaging device.
3.15 Dynamic Range Phantom
Dynamic range phantom refers to an ultrasonically tissue-mimicking phantom stepwise
composed of two parts (low-attenuation non-scattering gel and high-attenuation scattering gel)
along the depth direction, and specifically used to detect the dynamic range parameter of Type-
B ultrasonic imaging device.
4 Technical Requirements for Tissue-mimicking Phantom
4.1 Multi-purpose Phantom and Small Part Phantom
4.1.1 Sound velocity of TM material
The sound velocity of the TM material used for the multi-purpose phantom and small part
phantom should be (1,540 10) m/s.
NOTE: the sound velocity value is measured at (23 3) C. In order to satisfy the test requirements
of specific Type-B ultrasonic performance indicators, the user of the phantom may also
choose a phantom with a specific sound velocity, but it shall be indicated in the report. See
Appendix B for the description of technical requirements for the sound velocity of the TM
material.
4.1.2 Sound attenuation coefficient slope of TM material
The sound attenuation coefficient slope of the TM material used for the multi-purpose phantom
and small part phantom should be between 0.2 dB/(cm MHz) ~ 0.9 dB/(cm MHz). The user
Appendix A
(informative)
Description of Two Measurement Methods for Detection Depth of Type-B Ultrasonic
Imaging
From the perspective of clinical demands, people expect that Type-B ultrasonic imaging can
detect a greater depth in human body. The technical parameter characterizing this performance
is “detection depth”, but there are two methods for measuring this parameter: scattered light
point method and line target method.
The University of Wisconsin-Madison and Radiation Measurement Inc. (RMI) are international
pioneers of ultrasonic phantoms, and also, the earliest proposers of the measurement methods
for Type-B ultrasonic imaging performance. Their definition of the detection depth of Type-B
ultrasonic imaging is the maximum depth of TM material that can be displayed by the scattered
light points of the image when the focus of the sound beam of the equipment under inspection
is set at the farthest point, and the output power and receive gain are set at the maximum.
Conceptually speaking, this definition is undoubtedly consistent with clinical practice. However,
the problem is that the application of this definition to a formal quality assurance detection
program must satisfy a pre-requisite: the sound velocity, sound attenuation coefficient slope and
backscattering coefficient of the TM material used for the ultrasonic phantoms must be clearly
specified in advance, which requires the adoption of standardized methods for accurate
measurement. However, it is well-known that despite years of endeavors by the authorities in
developed countries in Europe and the United States, the standardized measurement of the
backscattering coefficient of the TM material has not yet been resolved. As a result, in the
international standard IEC 61685:2001 concerning the Doppler phantom, there are only two
experimental research papers that can be quoted as references for the measurement of the blood-
mimicking backscattering coefficient, rather than formal standards on the measurement
methods. For the measurement of the acoustic property parameters of TM material, although
YY/T 0458, which was transformed from IEC 61685:2001, is quoted in GB/T 15261,
standardized measurement is only truly realized in sound velocity and sound attenuation
coefficient. Under the circumstance where the backscattering coefficient of TM material cannot
be stipulated and there is no standardized method for detection and verification, for the same
Type-B ultrasonic imaging device, on phantoms with the same sound attenuation coefficient
but different backscattering, the measured detection depth must be different. Under the extreme
circumstance where only the sound attenuation property of TM material complies with the
requirements, while there is no visible backscattered light point (pure absorption or very weak
scattering) on the echo image, the reading of the detection depth approaches zero.
In view of the above-mentioned situation, since GB 10152 and GB 10153 was issued in 1988,
the domestic product standards on Type-B ultrasonic imaging have been taking the number of
longitudinal target lines visible in the image display when the sound beam is the farthest focused,
and the transmitted power and receive gain are the maximum as the detection depth. The
premise of adopting this definition is that the sound velocity and sound attenuation coefficient
Appendix B
(informative)
Description of Technical Requirements for TM Material and Target Line
As the primary means of detecting the performance of Type-B ultrasonic imaging,
ultrasonically tissue-mimicking phantom has prominent characteristics of mimicking,
quantification and standardization. Mimicking means that the medium that constitutes the
phantom mimicking the acoustic properties of human soft tissue; quantification means that
there are quantitative requirements for the acoustic properties of TM material, and the acoustic
properties, structural characteristics and spatial layout of the target; standardization means that
within a certain region, department, system and for a specific purpose, uniform regulations are
formulated for the technical characteristics of the phantom.
Since the early 1980s, the most representative requirements for the acoustic properties of TM
material used for the ultrasonically tissue-mimicking phantom are: the sound velocity is (1,540
10) m/s, the sound attenuation coefficient has an approximately linear relationship with the
frequency, and the slope is (0.7 0.05) dB/(cm MHz); the diameter of the nylon target line is
(0.3 0.05) mm, and the geometric position tolerance is 0.1 mm. However, at the end of the
last century, some manufacturers adopted TM material with a sound attenuation coefficient
slope of (0.5 0.05) dB/(cm MHz) and nylon target line with a diameter of 0.1 mm, and the
spacing of target lines in the target group for detection depth was either 10 mm or 20 mm. This
presents the user with a need-based choice. In this regard, two situations should be distinguished:
if it is a research experiment without standard technical requirements, or only general
qualitative observation is conducted, the technical parameters of the phantom used can be
selected in accordance with its specific purpose; otherwise, if it is a product quality inspection
based on specified standards, then, the acoustic properties of TM material used for the ultrasonic
phantom, and the diameter and spacing of nylon target lines must comply with the stipulations
in the corresponding standards. The specific reasons are as follows:
a) The influence of sound velocity of TM material on the detection result of Type-B
ultrasonic imaging performance
1,540 m/s is the internationally recognized average sound velocity of human soft
tissue. Many design calculations of medical ultrasonic instruments, such as: the
longitudinal and transverse geometric scales of the formed images, the time-space
relations in the measurement of distance, perimeter and area, the prediction of focal
length and focal area size of acoustic lens and electronic focusing, scanning angle,
and the design of line number and frame rate, are based on such recognition. If the
ultrasonic phantom used in the performance detection of Type-B ultrasonic imaging
product violates this regulation, then, the technical characteristics of the product
related to the above-mentioned design calculations will not be verified, and it will
inevitably lead to distorted evaluation of the quality of the inspected product due to
the shape distortion and numerical misalignment of the phantom image.
A research conclusion published by A. Goldstein, Department of Radiation Physics,
School of Medicine of Wayne University, Michigan State, USA in 2000 is that the
ultrasonic phantom with a sound velocity different from 1,540 m/s cannot be used to
check the distance measurement error of Type-B ultrasonic imaging device equipped
with line array, convex array, phased array and vector array probes, nor can it be used
to measure and predict the focusing function of the probes in clinical practice.
A research conclusion published by Dudley et al., Department of Medical Physics of
Nottingham City Hospital, HK and P. D. Clark of Newcastle General Hospital in 2002
is that in the low-sound-velocity phantoms, the ultrasonic beam profile was
significantly broadened. Users who require accurate results of sound beam profile
measurement should use the sound propagation medium with a sound velocity of
1,540 m/s. Different types of phantoms lead to different results, so when conducting
serial comparisons of ultrasound scanners, one type of phantom should be fixed.
In 2004, A. Goldstein issued a paper on this issue again and pointed out: it has been
proved that phantoms with a sound velocity lower than 1,540 m/s will generate wrong
sound beam width measurement results. This error is larger for electronically focused
transducers than for mechanically focused ones. Therefore, the low-sound-velocity
phantoms should be limited to qualitative examination of equipment performance.
A research conclusion published by Q. Chen and J. A. Zagzebski, Department of
Medical Physics of University of Wisconsin-Madison in 2004 is that if the sound
velocity in the medium used for the ultrasonic phantom is different from the assumed
sound velocity value in the sound beam former of the ultrasonic scanner, it will not
only cause an error in the position of the line target in the ultrasound image, but also
cause the dynamic receiving focusing to ignore the line target. As a result, the lateral
pulse-echo profile of the image formed by the target broadens. For the polyurethane
rubber material with a sound velocity of 1,450 m/s, since its value is 6% lower, the
width of sound beams increases to 200% ~ 500%.
b) The influence of sound attenuation of TM material on the detection result of Type-B
ultrasonic imaging performance
Human tissue has an attenuation effect on ultrasonic waves. This effect has two
consequences: on the one hand, the tissue with greater attenuation can be “seen” by
the ultrasonic waves; on the other hand, due to the existence of the “beam-hardening”
effect of the sound beams, the tissue with greater attenuation will have a severer loss
of high-frequency components, and the deterioration of lateral resolution and slice
thickness will be more serious. Accordingly, under the circumstance where the sound
attenuation coefficient slope of TM material used for the ultrasonic phantom is
specified as (0.7 0.05) dB/(cm MHz), if the phantom of (0.5 0.05) dB/(cm
MHz) is used instead (or vice versa), or is within the frequency band used by the
phantom, and the relations between the sound attenuation coefficient of TM material
and the frequency are not a straight line, then, only distorted measurement results of
detection depth, lateral resolution and slice thickness can be obtained.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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