• 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.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.1
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• pp.91-97
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• 2015

PURPOSE: In this study investigated the thermal effect in tissue mimicking phantom by the material of the ultrasonic transducer in low intensity sonication. METHODS: The material of the ultrasonic transducer was made of ceramic, stainless steel, aluminum. Korea Testing Laboratory was measured of the three kinds of materials the total output of the ultrasonic transducer. Each material was measured core temperature and the actual output depending on the type of transducer. Agarose tissue mimicking phantom and silicone tissue mimicking phantom was made. Transducers made of three kinds of materials were emitted in the phantom. It is shown as a graph about time and temperature and the surface temperature rising speed and deep temperature rise rate was investigated. RESULTS: Ceramic transducers were highest output. Higher than the stainless steel transducer, aluminum had the lowest total output. Deep temperature was the highest in the ceramic transducer, and the surface temperature was the highest in the stainless steel transducer. Thermal images of ceramic transducer showed that a valid output is formed deeper wider than the metal. CONCLUSION: Ceramic transducer is confirmed the excellence than the metal transducer in deep thermal effect and the actual output of the ultrasound.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.1
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• pp.70-75
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• 2012

Purpose: It is important to acquire accurate data because the SPECT scan affected by various physical factors. The aim of this study was to compare the uniformity when both centers were matched or mismatched differed from position of heart in COR. Materials and methods: The images were acquired with cylindrical uniform phantom (6.7 cm diameter, 9 cm length) and heart insert phantom using Cardio MD SPECT system (Philips, USA). The phantoms were positioned on COR as well as four different points which were 10 cm above, below, left and right side from the COR. The counts from the both edge of cylindrical uniform phantom and those from the both wall of heart insert phantom were compared by using vertical and horizontal line profile. In addition, the qualitative evaluation was performed with heart insert phantom images and volunteer test. Results: In heart insert phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 1.1, 4.1, 4.9, 2.2 and 0.9% using T-A curve for horizontal view. In case of vertical view of COR 3.9, 21.9, 3.5, 23.9, 14.0% were shown. In cylindrical phantom study, the differences of counts between COR and 10 cm above, below, left and right point of COR were 4.3, 0.3, 3.3, 2.6 and 0.7% using T-A curve for horizontal view. In case of vertical view of COR 2.7, 3.0, 1.0, 0.3, 3.4% were shown. For qualitative evaluation, the images at COR were the most uniform for both of heart insert phantom and volunteer test, whereas other four positions showed somewhat distorted images. Conclusion: It showed the most uniform images when COR is matched with the heart. Therefore, we can expect that distortion which increased or decreased of myocardial perfusion will be prevented by matching the heart and COR when positioning. Furthermore, the accuracy of diagnosis will be improved as well.

• Journal of radiological science and technology
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• v.41 no.4
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• pp.289-295
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• 2018

When using a mobile X-ray unit, primary radiation creates medical images and secondary radiation scatters in many directions, which reduces image quality and causes exposure to patients, care givers and medical personnel. The purpose of this study was to develop a radiation shielding system for effectively shielding secondary radiation and evaluate its effectiveness. Using a mobile X-ray unit, spatial dose according to presence of human equivalent phantom and spatial dose using the developed shielding device were measured, and the phantom at 80 cm equidistance from center of X-ray was compared with spatial dose according to use of a shield. Measurements were taken at intervals of 10 cm every $30^{\circ}$ from the head direction($-90^{\circ}$) to the body direction($+90^{\circ}$). In the spatial dose measurement with and without the phantom, when the human equivalent Phantom was used, the spatial dose was increased by 40% in all directions from 40 cm to 100 cm from the central X-ray, and about 88% of the space dose was reduced when using the developed shields with the phantom. The equidistance dose at 80 cm from the central X-ray was increased by 39% from $5.1{\pm}0.26{\mu}Gy$ to $7.1{\pm}0.15{\mu}Gy$ when the human equivalent phantom was used, and when phantom was used and shielding was used, the spatial dose was reduced by about 90% from $7.1{\pm}0.15{\mu}Gy$ to $0.7{\pm}0.07{\mu}Gy$. The spatial dose of natural radiation was measured to be about $0.2{\pm}0.04{\mu}Gy$ when using the developed shielding with Phantom at a distance of 1 m or more. It is expected that by using the developed shielding system, it will be possible to effectively reduce secondary radiation dose received in all directions and to ensure safe imaging.

• Journal of radiological science and technology
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• v.41 no.1
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• pp.33-38
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• 2018

There are limits to check the lesion as inserting a breast implant patients. So the application of BSGI based on Nuclear Medicine examination has increased. In this study, therefore we confirmed the effect of the image applying to breast implants in Breast Specific Gamma Imaging. We utilized Dilon 6800 BSGI scanner and developed the phantom. The self-development phantom was a rectangular shape of $230{\times}190{\times}80mm$ size and had 5 spheres which consisted of diameters of 10, 13, 17, 22, 28 mm in central part. We injected $^{99m}TcO_4$ into the self-development phantom in the proportion of four to one and made each additional phantom filled with 0.9 % sodium chloride, silicon and paraffin. Each additional phantom was placed between detector and self-development phantom. Each image was acquired five times depending on the type and thickness of the additional phantom. Statistical analysis with SPSS ver.18 was applied. In the test of variation according to the thickness of all additional phantoms, as the phantoms which 0.9% sodium chloride, silicon and paraffin increased, the attenuation variation was higher(P<0.005). There was no significant difference in the attenuation variation and the quality of image for type of the additional phantom. Therefore, if the effect of the image applying to breast implants in Breast Specific Gamma Imaging is confirmed, the higher diagnostic value can be achieved.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.103-109
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• 2022

To maintain improved image quality in mammography, the quality control process is performed using the ACR (American college of radiology) phantom. In addition, many studied were performed by fabricating the customized breast phantom to provide more information in mammography. Thus, the purpose of this study was to evaluate the image quality by designing the modified ACR phantoms. The five modified acrlylic ACR phantoms were designed by considering insert position and phantom thickness. The phantoms were consisted of 4.5, 3.0, and 1.5 cm in terms of phantom thickness, and 3.0, 2.0, and 0.5 cm in terms of insert position, respectively. The acquired images were evaluated by PSNR (peak signal to noise ratio), RMSE (root mean square error), CC (correlation coefficient), CNR (contrast to noise ratio), and COV (coefficient of variation). Based on the similarity analysis, the result is suitable between conventional and new designed phantoms. In addition, the CNR and COV results in terms of insert position showed that image quality for 0.5 cm was 2.3 and 27.4% improved compared with 2 and 3 cm, respectively. According to phantom thickness results, the CNR result for 1.5 cm and COV result for 4.5 cm were 50.1 and 62.7% improved compared with that those conditions. In conclusion, we confirmed that the image quality depends on the breast size and thickness through modified ACR phantom study.

• 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.

• Korean Journal of Radiology
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• v.22 no.8
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• pp.1332-1340
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• 2021

Objective: To evaluate the feasibility of a new three-dimensional (3D) MR fingerprinting (MRF) technique for the prostate gland by conducting phantom and clinical studies. Materials and Methods: The new 3D MRF technique used in this study enables quick data acquisition and has a high resolution. For the phantom study, the MRF T1 and T2 values in an in-house phantom were compared with those of goldstandard mapping methods using linear regression analysis. For the clinical study, we evaluated 90 patients who underwent prostate imaging with MRF for suspected prostate cancer between September 2019 and February 2020. The mean T1 and T2 values were compared in the peripheral zone, transition zone, and focal lesions using paired t tests. The differences in the T1 and T2 values according to cancer aggressiveness were evaluated using one-way analysis of variance. Results: In the phantom study, the MRF T1 and T2 values showed a perfect correlation with the gold-standard T1 and T2 values (R > 0.99). In the clinical study, the T1 and T2 values in the peripheral zone were significantly higher than those in the transitional zone (p < 0.001, both). The T1 and T2 values in prostate cancer were significantly lower than those in the peripheral and transitional zones. The higher the grade of cancer, the lower the T2 values. Conclusion: The T1 and T2 values obtained from the 3D MRF showed a perfect correlation with the gold standard values in the phantom study. Differences in the T1 and T2 values among the different zones of the prostate gland were identified using 3D MRF in patients.

• Journal of the Korean Society of Radiology
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• v.12 no.3
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• pp.427-433
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• 2018

Because of the expectation of the non-invasive treatment effect, Various studies on the treatment of varicose veins using focused ultrasound are reported. In this study, the bio-tissue phantom and tissue equivalent phantom that can be applied to estimation of ultrasonic varicose veins treatment effect. Each phantom was evaluated for its usefulness by evaluating the acoustic characteristics and the shrinkage rate according to the ultrasonic irradiation. A multi-layer structure phantom with three layers of skin, fat, and muscle was constructed considering the structure of the tissue where the varicose veins occurred. The materials constituting each layer were made to have characteristics similar to human body. In addition, the multi-layered phantoms with blood vessel mimic tube, with bovine blood vessel, and with animal tissue were fabricated. The degree of shrinkage of blood vessel mimic material and vascular tissue according to ultrasonic irradiation was evaluated using B-mode image. As the results of this study, it was thought that the proposed phantom could be used effectively in the evaluation of ultrasonic varicose veins treatment. In addition, it is thought that these phantoms could be applied to the development of varicose vein treatment device using the focused ultrasound and the verification of the therapeutic effect.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.450-453
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• 2002

In radiotherapy treatment planning, it is critical to deliver the radiation dose to tumor and protect surrounding normal tissue. Recent developments in functional imaging and radiotherapy treatment technology have been raising chances to control tumor saving normal tissues. A brain phantom which could be used for image registration technique of CT-MR and CT-SPECT images using surface matching was developed. The brain phantom was specially designed to obtain imaging dataset of CT, MR, and SPECT. The phantom had an external frame with 4 N-shaped pipes filled with acryl rods, Pb rods for CT, MR, and SPECT imaging, respectively. 8 acrylic pipes were inserted into the empty space of the brain phantom to be imaged for geometric evaluation of the matching. For an optimization algorithm of image registration, we used Downhill simplex algorithm suggested as a fast surface matching algorithm. Accuracy of image fusion was assessed by the comparison between the center points of the section of N-shaped bars in the external frame and the inserted pipes of the phantom and minimized cost functions of the optimization algorithm. Technique with partially transparent, mixed images using color on gray was used for visual assessment of the image registration process. The errors of image registration of CT-MR and CT-SPECT were within 2mm and 4mm, respectively. Since these errors were considered within a reasonable margin from the phantom study, the phantom is expected to be used for conventional image registration between multimodal image datasets..