• IEIE Transactions on Smart Processing and Computing
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• v.3 no.3
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• pp.153-159
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• 2014

As the number of treatments in the therapeutic ultrasound field targeted at fat tissue increase, the performance of the equipment should be evaluated for safety using a fat phantom. In this study, a fat phantom was fabricated using olive oil and a tissue-mimicking material (TMM) phantom. To evaluate the acoustic properties of the TMM phantom according to the changes in the olive oil, the composition ratio of a liquid mixture of olive oil with a surfactant was adjusted from 5-20% in 5% steps. The acoustic properties of the phantom were evaluated using the sound velocity, attenuation coefficient, density, and acoustic impedance. The experimental results showed that the sound velocity decreased with increasing amount of olive oil but the other acoustic properties did not change. In addition, the phantom using an olive-oil mixture with a 15% composition ratio was most similar to the acoustic characteristics of fat tissue with a sound velocity of 1477.35 m/s, an attenuation coefficient of 0.514 dB/MHz-cm, a density of $1.07g/cm^3$, and an acoustic impedance of 1.575 MRayl. These experimental results are expected contribute to the accuracy of the results using a TMM phantom and will be useful for the therapeutic ultrasound field targeted at subcutaneous fat tissue.

• Restorative Dentistry and Endodontics
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• v.45 no.4
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• pp.45.1-45.8
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• 2020

Objective: The aim of this study was to introduce a gelatin/bovine serum albumin (BSA) tissue standard, which provides dissolution properties identical to those of biological tissues. Further, the study evaluated whether the utilization of endodontic activating devices led to enhanced phantom dissolution rates. Materials and Methods: Bovine pulp tissue was obtained to determine a benchmark of tissue dissolution. The surface area and mass of samples were held constant while the ratio of gelatin and BSA were varied, ranging from 7.5% to 10% gelatin and 5% BSA. Each sample was placed in an individual test tube that was filled with an appropriate sodium hypochlorite solution for 1, 3, and 5 minutes, and then removed from the solution, blotted dry, and weighed again. The remaining tissue was calculated as the percent of initial tissue to determine the tissue dissolution rate. A radiopaque agent (sodium diatrizoate) and a fluorescent dye (methylene blue) were added to the phantom to allow easy quantification of phantom dissolution in a canal block model when activated using ultrasonic (EndoUltra) or sonic (EndoActivator) energy. Results: The 9% gelatin + 5% BSA phantom showed statistically equivalent dissolution to bovine pulp tissue at all time intervals. Furthermore, the EndoUltra yielded significantly more phantom dissolution in the canal block than the EndoActivator or syringe irrigation. Conclusions: Our phantom is comparable to biological tissue in terms of tissue dissolution and could be utilized for in vitro tests due to its injectability and detectability.

• Nuclear Engineering and Technology
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• v.53 no.12
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• pp.4158-4165
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• 2021

In this study, tissue equivalency (TE) of a newly developed epoxy-based phantom to 3-5 years child's tissue was investigated in paediatric energy range. Epoxy-based TE-phantoms were produced at different glandular/adipose (G/A) ratios of 17/83%, 31/69%, 36/64% and 10/90%. A procedure was developed in which specific amounts of boron, calcium, magnesium, sulphur compounds are mixed with epoxy resin, together with other minor substitutes. In paediatric energy range of 40-60 kV_p half-value layer (HVL) values were measured and then Hounsfield Units (HU) were determined from Computed Tomography(CT) scans taken in the X-ray energy range of 80-120kV_p. It is found that radiation absorption properties of these phantoms in terms of the measured HVL values related to linear attenuation coefficients (µ) are very well mimicking a 3 years child's soft tissue in case a ratio of 10/90%G/A. Additionally, the HU values of phantoms were determined from the CT scans. The HU = 47.8 ± 4.8 value was found for the epoxy-based phantom produced at a ratio of 10/90%G/A. The obtained HVL and HU values also support the suitability of the new epoxy based-phantom produced at a ratio of 10/90%G/A for a satisfactory mimicking a 3 years child's soft tissue by 5%. Thus they can have a potential use to perform the quality controls of medical X-ray systems and dose optimization studies.

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.4
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• pp.368-373
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• 2009

A human tissue mimicking phantom is constructed to assess the performance of a medical ultrasound elasticity imaging system. In a human body, the tumor or cancer is stiffer than its surrounding normal tissue. A technique fur imaging the elasticity of such a tissue is referred to as elastography. Homogeneous elasticity phantoms with differing Young's moduli are constructed using a plastic hardener and softener to simulate the mechanical characteristics of a diseased human tissue. The Young's modulus of the fabricated homogeneous phantom materials were measured from 11.1 to 79.6 kPa depending on the mixing ratio of the amount of the hardener to that of the softener. An ultrasound lesion mimicking phantom was made of these materials, and ultrasound elasticity imaging was performed on it. It is confirmed in this paper that the fabricated plastic-based elasticity phantom is useful in representing the elastic characteristics of a human tissue.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.30-35
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• 2011

Purpose: The Boramae Hospital are currently using Wide beam reconstruction (WBR: UltraSPECT, Israel) to improve the resolution. The Xact-bone belongs to the WBR. It has been reported that Xact-bone helps us to improve image resolution and contrast. This study will be evaluated clinical usefulness of Xact-bone method. Materials and Methods: The usefulness evaluation of Xact-bone method was analyzed in resolution test and contrast ratio. The resolution test in Planar image were obtained from Full width at half maximum (FWHM) by using capillary tube. And the contrast ratio was obtained from Bone and Soft tissue (B/S) ratio values that were acquired from bone scan study of 50 patients before and after using the Xact-bone method. We prepared the Triple Line Source Phantom, NEMA IEC Body Phantom and Standard Jaszczak Phantom to acquire the FWHM and Contrast Ratio values of Single photon emission computed tomography (SPECT) image. Subsequently we compared among the Filtered backprojection (FBP), Orderd subset expectation maximization (OSEM) and Xact-Bone image. Results: The results of the planar Xact-bone data improved resolution about 20% by using capillary tube. In addition it was improved B/S ratio about 15%. When using Triple Line Source Phantom, SPECT Xact-bone data improved resolution for both FBP, OSEM methods about 20% and 10%, respectively. Contrast ratio in each spheres has also been increased for both methods that using NEMA IEC body Phantom and Standard Jaszczak Phantom. Conclusion: When we were using Xact-bone method, we could see to improve the resolution and Contrast ratio as compared to do not use the Xact-bone method. Accordingly, by using WBR's Xact-bone method is expected to improve the image quality. However, when introducing new software, it is needed to match the characteristics of the hospital protocol and clinical application.

• Journal of radiological science and technology
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• v.5 no.1
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• pp.21-34
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• 1982

When unattenuated x-ray radiation passes through the object it is transmitted and scattered from objectes and impinging on the film. During this process certain radiation is absorbed within the object and others transmitted in reduced scattering. The scattering radiation influence upon radiation image quality, confining x-ray beam which means scattering radiation produce increased fog on x-ray film image and as a consequence decrease contrast and less detail of the film there for the elimination of fog and for absorbing scattered radiation, the grid has been used between the object and the film in order to rid of scattering rays. Using grid is good method for the qualification of the better image as well as in using air gap technique. The grid is easy to manipulate and promote good efficiency which is defined by ICRU and JIS. It is the purpose to study for eliminating scattered radiation from the tissue equivalent acryl phantom using grid, we have studied and evaluated the grid permeability about the x-ray exposure, the selection of grid ratio according to phantom thickness, on x-ray exposure are performed as follows. 1. The penetrating ratio of primary x-ray is remarkably decreased by increasing of the grid ratio, but it is almost not influenced in KVP difference and phantom thickness. 2. The scattered radiation is proportionaly increased by thickness of the phantom, having nothing to do with grid ratios. 3. The relative between the penetration rate of primary and secondary x-ray is improved by increasing grid ratio, and decreased by phantom thickness, and slightly decreased by high tube voltage. 4. The grid of 5:1 and 10:1 ratio are adequate to the phantom of 10cm and 15cm thickness, respectively.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.11-20
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• 1998

The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.

• Radiation Oncology Journal
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• v.7 no.1
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• pp.133-140
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• 1989

Three-dimension paraffin compensator was designed to construct the tissue equivalent compensator for irregular body contours and obiliques beam incidence. The ratio of compensator thickness to tissue deficit was depended on field size, depth and air gap because the scattered dose loss. The ratio of compensator-tissue was optimized 0.79, 0.73, 0.61 and 0.56 in 6MV x-rays as function of field size $4{\times}4$, $10{\times}10$, $20{\times}20$ and $30{\times}30cm^2$ respectively. in our study. Using this tissue equivalent compensator, it can be got 2% difference of dose at same mid-plane in phantom study.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.21-26
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• 2016

Purpose Because of many advantages, PET-CT Scanners generally use CT Data for attenuation correction. By using CT based attenuation correction, we can get anatomical information, reduce scan time and make more accurate correction of attenuation. However in case metal artifact occurred during CT scan, CT-based attenuation correction can induce artifacts and quantitative errors that can affect the PET images. Therefore this study infers true SUV of metal artifact region from attenuation corrected image count -to- non attenuation corrected image count ratio. Materials and Methods Micro phantom inserted $^{18}F-FDG$ 4mCi was used for phantom test and Biograph mCT S(40) is used for medical test equipment. We generated metal artifact in micro phantom by using metal. Then we acquired both metal artifact region of correction factor and non metal artifact region of correction factor by using attenuation correction image count -to- non attenuation correction image count ratio. In case of clinical image, we reconstructed both attenuation corrected images and non attenuation corrected images of 10 normal patient($66{\pm}15age$) who examined PET-CT scan in SNUH. After that, we standardize several organs of correction factor by using attenuation corrected image count -to- non attenuation corrected count ratio. Then we figured out metal artifact region of correction factor by using metal artifact region of attenuation corrected image count -to- non attenuation corrected count ratio And we compared standard organs correction factor with metal artifact region correction factor. Results according to phantom test results, metal artifact induce overestimation of correction factor so metal artifact region of correction factors are 12% bigger than the non metal artifact region of correction factors. in case of clinical test, correction factor of organs with high CT number(>1000) is $8{\pm}0.5%$, correction factor of organs with CT number similar to soft tissue is $6{\pm}2%$ and correction factor of organs with low CT number(-100>) is $3{\pm}1%$. Also metal artifact correction factors are 20% bigger than soft tissue correction factors which didn't happened metal artifact. Conclusion metal artifact lead to overestimation of attenuation coefficient. because of that, SUV of metal artifact region is overestimated. Thus for more accurate quantitative evaluation, using attenuation correction image count -to-non attenuation correction image count ratio is one of the methods to reduce metal artifact affect.

• Journal of Biomedical Engineering Research
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• v.29 no.4
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• pp.302-306
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• 2008

Plastic hardener and softener based ultrasound phantoms were made in various constitutions and their acoustic properties were measured. Speed of sound is approximately $1.4\;mm/{\mu}sec$ in all the phantoms, which is about 7% less than that of in soft tissue. Attenuation coefficient is strongly dependent on the ratio between hardener and softener. In order to achieve the tissue level attenuation (0.5 dB/cm/MHz), 60% of hardener or less is required. The synthesized phantoms can be preserved for more than 6 months without structural degradation.