This standard specifies the acoustic characteristic parameters and measurement methods of ultrasonic human tissue-mimicking materials. This standard is applicable to the measurement of the density of standard samples of this material and the sound velocity and acoustic attenuation coefficient in the frequency range of 1 to 10 MHz. GB/T 15261-1994 Measurement method of acoustic characteristics of ultrasonic human tissue-mimicking materials GB/T15261-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Methods of measuring the acoustic characteristics of ultrasonically tissue-mimicking materials1 Subject content and scope of application
This standard specifies the acoustic characteristic parameters and measurement methods of ultrasonically tissue-mimicking materials. GB/T 15261—94
This standard is applicable to the measurement of the density of standard samples of this material and the sound velocity and acoustic attenuation coefficient in the frequency range of 1 to 10 MHz. 2 Reference standards
GB3102.7 Acoustic quantities and units
GB3947 Acoustic terms
3 Terms
3.1 Ultrasonic tissue-mimicking materialsUltrasoundly tissue-mimicking materials Materials that simulate human tissue in terms of ultrasonic characteristics. Referred to as TM materials. 3.2 Ultrasound phantomsUltrasound phantomsPassive devices that simulate the basic ultrasonic parameters of human soft tissues, used for the measurement of parameters of medical ultrasonic instruments or for the display of simulated anatomical characteristics.
3. 3 Slope of attenuation coefficient The slope of the curve of sound attenuation and frequency, unit: dB/(cm·MHz). 4 Measurement parameters
4.1 Density: 900~1100kg/m2±1%. 4.2 Sound velocity: 1400~1600m/s±10m/s. 4.3 Slope of sound attenuation 0.3～1.2dB/(cm·MHz)±0.05dB/(cm·MHz). 5 Measurement method
5.1 Density
The density should be determined by directly measuring the mass and volume of the TM material sample at 22C. The sample volume should be no less than 150cm2 to ensure an accuracy within ±1%.
5.2 Sound velocity
5.2.1 Measurement principle
The sound velocity is measured by the pulse substitution method. The testing principle of the pulse substitution method is shown in the figure below. The container C contains constant temperature degassed distilled water W. The RF pulse generator excites the transducer T through resonance and radiates ultrasonic pulses into the water. The pulse is received by the transducer T2, amplified, and displayed on the oscilloscope after attenuation. When a sample with a thickness of D is inserted into the sound path between T1 and T2, the propagation time of ultrasound between T2 and T2 will change by △t. When the propagation time is shortened after the sample is inserted, △t takes a negative value, otherwise it takes a positive value. Cw and Cs represent the sound speed of water and sample respectively, then: DCw
D+ ACw
In the formula, the recognized accurate value of Cw can be found in the literature. As long as the sample thickness D and time shift △t are measured, Cs can be obtained. Delay trigger circuit
RF pulse generator
Water tank C
22 ± 0. 1℃ degassed water W
Transmitting transducer T,
5.2.2 Measuring instruments and main components
RF pulse generator:
Frequency range: 1～10 MHz;
Pulse width: 1～30 μs,
Repetition frequency: 50~200Hz;
Amplifier
Pulse substitution method test schematic
Pulse amplitude (peak-to-peak): adjustable within 100V; amplitude variation: ±0.05dB.
Oscilloscope:
Bandwidth: 0~40MHz;
Time axis error: ±3%;
Amplitude axis error: ±3%.
Sample requirements:
Wavelength filter
Attenuator
Receiving transducer T
Sample s
（1）
Its diameter is more than twice the diameter of the test transducer. The thickness is 2.5cm and 5cm (single sample method or double sample method), the accuracy is 57
GB/T 15261--94
±0.05rmm, and the two ends of the test box are sealed with plastic film (50 or 70um polyester film is used to bond and seal with the box wall). d. Transmitting and receiving transducers:
Made of X-zero cut quartz crystal or piezoelectric ceramic crystal. 5.2.3 Test steps:
5.2.3.1 Adjust the transmitting and receiving transducer surfaces to be parallel and align their acoustic axes. 5.2.3.2 Place the sample in a test water tank at 22±0.1℃ and keep the temperature above 1# to make the sample surface fully wetted and free of bubbles. 5.2.3.3 Select a wider pulse and a lower speed oscilloscope scan mode, adjust the delayed trigger, so that the first received pulse is displayed on the oscilloscope screen, which contains only a few carrier cycles and has an obvious maximum value at the center. 5.2.3.4 Place the sample and roughly determine the range of the A value by the displacement of the pulse maximum value, then remove the sample. 5.2.3.5 Increase the pulse width so that the pulse contains more carrier cycles to ensure that it contains a relatively simple spectrum component. At the same time, select the fast scan mode and adjust the delayed trigger so that the intersection of the carrier at the center of the pulse and the horizontal scale of the oscilloscope is displayed on one side of the screen. 5.2.3.6 Insert the sample again, and move the intersection to the other side of the screen. The △t value can be read directly from this. 5.2.3.7 Measure the sample thickness D with a vernier caliper. 5.2.3.8 Determine Cs from the measured At and values. 5.3 Acoustic attenuation coefficient
Using the pulse insertion substitution method, like the sound velocity measurement, when a sample with a thickness of D is inserted in the sound path between T1 and T2, the sound pressure value received by T2 will change. This change can be observed on the oscilloscope (or compensated by changing the attenuation of the attenuator so that the amplitude of the received pulse displayed on the oscilloscope screen is equal before and after the sample is placed. Obviously, the compensation of the attenuator at this time is the total attenuation of the sample insertion, expressed as B
5.3.1 Single sample method || tt||Measure the pulse amplitudes V. and V? when inserting into the TM material sample and the steamed stuffing water sample of the same thickness D, and calculate the attenuation coefficient αg according to the following formula.
g(dB/cm)-
where D is the sample thickness, cm*
V is the corresponding pulse amplitude when inserting into the TM material sample, VV is the corresponding pulse amplitude when inserting into the distilled water sample, V; aw is the acoustic attenuation coefficient of water, dB/cm.
Note: For 23C distilled water:
aw 2.0X103f
Where: αw Acoustic attenuation coefficient of plane sound wave in liquid, dB/cm Super-Mag frequency, MHz
5.3.2 Double sample method
·（2）
Measure the pulse amplitude V, and V2 when inserting TM material samples of different thicknesses (D1, and D2), and calculate the attenuation coefficient αs according to the following formula. V
a, (dB/cm)
Where: D.—thick sample thickness, cm;
Dg-——thick sample thickness, cm,
V. The corresponding pulse amplitude when inserting a thick sample, VV~--The corresponding pulse amplitude when inserting a thin sample, V8
Acoustic attenuation coefficient of water, dB/cm.
GB/T 15261--94
5.3.3 In the frequency range of 1-10MHz, use probes of different frequencies to measure the acoustic attenuation coefficient α. The measurement frequency points shall be no less than four and shall be evenly distributed. bzxz.net
5.3.4 With the frequency as the horizontal coordinate (MHz) and the acoustic attenuation coefficient as the vertical coordinate (dB/cm), make a linear regression of the measured data. The deviation between the measured value and the straight line shall comply with the provisions of Articles 4 and 3. Additional notes:
This standard is proposed by the State Food and Drug Administration. This standard is under the jurisdiction of the Medical Ultrasonic Equipment Standardization Subcommittee of the National Technical Committee for Standardization of Medical Electrical Appliances. This standard was drafted by the China Institute of Metrology, the Institute of Acoustics of the Chinese Academy of Sciences, and Nanjing University. The main drafters of this standard are Xiong Dalian, Niu Fengqi, and Feng Ruo. 59
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.