• The Journal of Korean Society for Radiation Therapy
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• v.29 no.1
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• pp.93-101
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• 2017

Purpose: In breast cancer radiotherapy, brass mesh bolus has been recently studied to overcome disadvantage of conventional bolus. The purpose of this study is to investigate the stability of first introduced the brass mesh in the country, and evaluate the skin surface dose of that. Materials and Methods: The measurement of skin surface dose was evaluated to verify similar thickness of the Brass mesh bolus that compared conformal tissue equivalent bolus with 5 mm thickness. We used 6 MV photons on an ELEKTA VERSA linear accelerator and optically stimulated luminescent dosimeter (OSLD). In addition, two opposed beam using IMRT phantom was applied to comparative study of brass mesh bolus between tissue equivalent bolus. Results: The results showed that similar thickness of the Brass mesh bolus was 3 mm compared with 5 mm tissue equivalent bolus by measuring the skin surface dose of solid phantom. The surface dose for IMRT thorax phantom using 3 mm brass mesh bolus was about 1.069 times greater than that using tissue equivalent bolus. Conclusion: In this study, we found that the brass mesh bolus improved better reduction of skin sparing effect and dose uniformity than tissue equivalent bolus. However evaluation for various clinic cases should be investigated.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.985-991
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• 2023

A tissue-equivalent phantom is necessary for quality control of hyperthermia therapy. However, since there is no phantom for this purpose, phantoms made from agar are being used in various studies. The tissue-equivalent properties of the agar phantom were confirmed by comparison with the tissue-equivalent material bolus in this study. CT images of the agar phantom and bolus were acquired, and tissue equivalent characteristics were analyzed with image analysis and dose calculation using a computerized radiation therapy planning system. The average pixel value was 96.960±10.999 in bolus, 108.559±8.233 in 3% agar phantom, and 111.844±8.651 in 4% agar phantom. Using the SSD technique, 100 cGy was prescribed at a depth of 1.5 cm and 6 MV X -ray was set to irradiated to 10x10 cm2, and the absorbed dose according to depth was calculated from the central axis of the beam. The intraclass correlation coefficient of dose distribution of bolus, 3% agar phantom, and 4% agar phantom was 0.979 (p<.001, 95%CI .957-.991). The density (g/cm3) at the point where the absorbed dose was calculated was 0.990±0.020 at the bolus, 1.018±0.020 at the 3% agar phantom, and 1.035±0.024 at the 4% agar phantom. In this study, the internal density distribution and uniformity of the agar phantom were confirmed to be appropriate as a tissue equivalent material by analysis of CT images and a computerized radiation therapy planning system.

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.154-155
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• 2011

• Progress in Medical Physics
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• v.9 no.4
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• pp.247-257
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• 1998

For effective radiotherapy, it should always be considered that calculation of different dose distribution in heterogenous tissue is important particularly on lung which has low density and large volume. To take precise dose distribution of 6MV X-ray in the thoracic cage, the authors had made a tissue equivalent phantom for thorax, measured dose distribution by thermoluminescent dosimeter and mm dosimeter, and derived methmetical equation coincided with provided theoretical formula. In comparision with isodose curve on case of homogeneous soft tissue, dose of heterogeneous lung tissue had been shown increase about 4% per cm depth on one and multiportal field, less than 15% difference on rotation field for esophagus, and around 20% difference on rotation field for lung according to the degree of rotation angle that must be corrected by dose compensation.

• Journal of The Korean Radiological Technologist Association
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• v.25 no.1
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• pp.60.1-60.1
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.90-93
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• 1999

• The Journal of Korean Society for Radiation Therapy
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• v.9 no.1
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• pp.61-63
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• 1997

• 대한방사선치료학회:학술대회논문집
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• 1997.03a
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• pp.16-16
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• 1997

• 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.

• Journal of Radiation Protection and Research
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• v.4 no.1
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• pp.21-28
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• 1979

A calculation is presented of air-scattered gamma rays using the modified single-scattering approximation. The air-scattered tissue dose rates are calculated for a general purpose taking into account (a) the buildup and exponential attenuation, (b) the energy spectrum at the position of question and (c) the geometrical scattering volume in three dimensions. These calculations have been further modified to render them applicable to a typical field irradiation facility which is surrounded by a shield wall and in which the source is fitted with a beam collimating device. The results of the calculation include the energy spectra, angular distribution and tissue does rates at source-receiver separation distances of from 35m to 300m. The comparison shows that the present method developed may be generally adequate for the gamma-ray air-scattering problems in field irradiation facilities if energy and angular distribution at the shield are unimportant.