• Nuclear Engineering and Technology
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• 제56권1호
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• pp.241-246
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• 2024

The study was carried out by numerical integration based on the diffraction properties and elemental composition. The elemental compositions of breast tissues in the literature were tested. The photon attenuation coefficients calculated using the recent elemental composition were found within 0.2-16% for adipose tissue and within 0.04-17% for glandular tissue with the experimental reference data. The attenuation coefficients of cancerous breast tissue calculated according to the elemental content previously measured in breast cancer patients were found within 0-17% with experimental data in the literature. The attenuation coefficients are of great interest to medical research. To calculate realistic attenuation coefficients, the characteristic coherent scatter, which is most intense at small angles, must be considered. For this reason, experimentally measured form factor data were reviewed, and the most compatible one with the theoretical form factor data produced in this study was used at low momentum transfer x (0 < x ≤ 8 nm^-1). The differential linear coherent scattering distributions were calculated for an energy value of 17.44 keV and compared with their experimental counterparts.

• 대한의용생체공학회:의공학회지
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• 제5권1호
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• pp.39-46
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• 1984

In order to improve the performance of ultrasonic diagnostic equipment, it is important to development the signal processing considering the ultrasonic properties of biological medium and propagation mechanism in tissue. Attenuation coefficient is not only important factor to analyze propagation properties, but also it is significant to estimate it in view of tissue characterization, so we show one of the method to estimate attenuation coefficient of biological tissue and the results of estimation.

• 대한의용생체공학회:의공학회지
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• 제6권2호
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• pp.43-52
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• 1985

In this paper, the depth and attenuation coefficient are estimated from the mutilayered liver tissue which contained a inhomogeneous one using reflected ultrasonic signals and the abnormal one is detected quantitatively. Regarding a liver tissue as several reflectors, we analyzed each one by the frequency spectral difference method and discussed its attenuation characteristics. For the verification of this method, the liver pantom and acryle are used. And also we proved the usefulness through the experiment.

• 대한의용생체공학회:의공학회지
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• 제5권1호
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• pp.55-62
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• 1984

A digital spectrum analysis technique was used to estimate the tissue characteristic parameters (transmission velocity and attenuation coefficient) in the phantom study and the human liver's ultrasound scanning. The soft tissue equivalent phantom was made with the combination materials of agar, water, powdered graphite, and n-propyl alcohol. In the human study, twenty five normal subjects and three patients with liver diseases were studied using the ultrasonic reflection signals and the spectrum analysis method The following results were obtained; 1. The soft tissue-equivalent materical could be produced with various acoustic parameters by changing the composition amount of the powdered graphite and n-propyl alcohol. 2. Attenuation coefficients of normal human liver tissue were estimated to be 0. 36 dB/cm MHz$\pm$0.11. In patients with liver disese, tile attenuation coefficients were shown to be different from the above normal values.

• The Journal of the Acoustical Society of Korea
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• 제24권4E호
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• pp.132-138
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• 2005

The purpose of this study is to measure the acoustic properties of Tofu and Acorn Curd (Dotori Muk), which are possibly used as tissue mimicking materials (TMMs). Due to its availability and low cost, Tofu was suggested as a TMM by several researchers who measured only sound speed and attenuation. The acoustic properties of Tofu and Muk including the backscattering coefficient were measured in this paper. Sound speed was measured by the time shift in a pulse echo setup. Attenuation coefficients and backscattering coefficients were measured by a broadband method using both 5 MHz and 10 MHz transducers in the frequency domain. The measured acoustic properties of both Tofu and Muk are observed to be similar to those of biological tissues such as beef liver or beef heart.

• 대한의용생체공학회:의공학회지
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• 제11권2호
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• pp.227-232
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• 1990

As a part of the study on ultrasonic tissue characterization, conventional ultrasonic imaging system is interfaced to the personal computer to acquire raw ultrasonic signal. One approach for tissue charaterization is performed using the attenuation map to the conventional images and the resulting attenuation map images are compared and inspected inside the region of interest from the viewpoint of pattern analysis. Currently, these methods are applied and modified to effectively find out the differences between the normal control and the patients with liver cirrhosis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1243-1246
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• 1987

To characterize the biological tissues, the new methods to measure the frequency dependent attenuation are presented in this paper. In general, ultrasonic phase information was assumed by linear function of the frequency. But, the minimum phase function which characterizes the frequency dispersion of tissue was derived in [l]. It is very significant to measure the attenuation by using the minimum phase function to characterize the frequency dispersion of tissue. Therefore, a more efficient method measuring the frequency dependent attenuation are proposed by using the estimated sound velocity and polarity of reflected signal. To verify the algorithms, pulse reflection experiments are performed.

• 한국의학물리학회지:의학물리
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• 제9권4호
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• pp.259-266
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• 1998

코발트-60 근접조사선원을 대체할 Ir-l92 선원주변의 2차원적 선량분포를 얻기 위하여, 조사선량률과, 조직감쇠계수를 구하였다. 조직감쇠계수는 선원에서 20 cm 지점까지 실험식을 구하였다. ？보기 방사능은 조사선량상수를 사용하여 결정하였으며, 2.5mm 직경에 두께 2.5 mm 의 선원은 조직선량을 정하기 위해 선원을 4401 개로 분할하여 선원 자체의 흡수효과와 ？슐벽의 차폐 효과와 조직감쇠계수를 적용하였다. 조직감쇠계수는 4차식을 사용하여 1% 오차범위내에서 실험값을 얻을 수 있었으며, Meisberger 상수는 선원에서 많이 떨어질수록 오차가 커서, 10 cm 위치서 7%, 20 cm 에서 33%의 오차를 발견할 수 있었으나, 겉보기방사능과 선원모양 및 크기가 달라 다른 결과를 가져올 수 있다고 본다. 발표된 Ir-192 선원의 에너지스펙트럼을 이용한 선량률상수는 절삭에너지 10 keV인 경우 4.69 R$cm^2$/mCi-hr을 얻었으며 Air Kerma는 0.973 을 구하였다. 이 실험에서 고안 선원의 분할선원에 의한 선원자체흡수와 ？슐벽에 의한 감쇠는 실선원의 54.6%가 겉보기방사능으로 나타남을 알 수 있었으며, 선량계획에 이용하기 위해 단위 ？보기 방사능에 대한 2차원적 선량표를 준비함으로써 기하학적선량과 선량 비등방성을 쉽게 이용할 수 있도록 하였다.

• 대한전자공학회논문지
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• 제27권12호
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• pp.1916-1924
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• 1990

In this paper attenuation effect on the measurement and the tomography of nonlinear parameter is discussed. We perform computer simulation with the method using harmonic components and the method using secondary wave components, and then estimate attenuation effect through the results and compare two measurement techniques. According to simulation result the attenuation effect is more intensive as large n and \ulcorner, and the degree of the attenuation effect is represented as error functions. In the aspect of measuremnet techniques, the method using secondary wave components is more insensitive to attenuation effect than the method using harmonic compnents. We obtain the same result in the nonlinear tomography, and show that the attenuation compensive filter is required because the whole tomogram is affected by frequency dependent attenuation(or nonlinear attenuation)

• 한국방사선학회논문지
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• 제16권7호
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• pp.927-934
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• 2022

본 연구는 간 초음파 영상을 활용하여 정량적인 측정 분석을 통해 조직 내 감쇠 지수, 조직 내 산란 분포지수 값 분석과 함께 초음파 영상 소견 간 일치도를 알아보고자 하였다. 2022년 8월부터 2022년 10월까지 지방간이 의심되어 간 초음파 검사 처방을 받은 45명의 환자를 대상으로 간 초음파 검사를 시행하였다. 연구결과, 초음파 영상 소견과 조직 내 감쇠 지수 간 일치도 분석 결과 Kappa 값이 0.82(p<0.05)로 두 검사 방법 간 매우 높은 일치도를 보였다. 또한, 초음파 영상 소견과 조직 내 산란 분포 지수 간 일치도 분석 결과에서도 Kappa 값이 0.642(p<0.05)로 두 검사 방법 간 높은 일치도를 보였다. 지방간 예측 시 간 초음파 소견 및 정량적인 초음파 검사 기법인 조직 내 감쇠 지수, 조직 내 산란 분포 지수를 활용한다면 지방간 환자의 진행 정도를 판단할 때 도움이 될 수 있을 것으로 생각된다.