• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.35-35
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• 2003

목적 : 세기변조방사선치료의 정도관리 중 선량 분포의 비교에 관한 새로운 정량적인 방법을 제시하였다. 이 과정 중에서 선량의 기울기가 큰 영역에서의 문제점을 해결하기 위하여 최적화 알고리듬을 사용하였다. 대상 및 방법 : 필름을 통해 측정된 선량분포와 컴퓨터를 통해 구해진 선량분포를 각각 5mm 간격과 lmm 간격의 해상도로 컴퓨터를 이용해 2 차원 선량분포로 구현한다. 그 후 두 선량분포사이의 차이를 각 선량분 포의 원점을 일치시킨 후 구해낸다. 이때 일반적으로 두 선량분포 사이의 차이는 선량의 기울기가 큰 영역에서 상당히 크게 나타나게 되는데 이것은 측정 장비의 원점을 구하는 과정에서 발생되는 이차원 상의 미세한 원점의 불일치 효과로 선량의 차이가 선량의 기울기가 큰 영역에서 더욱 커지기 때문이다. 이 불일치를 보정하기 위해서, 측정된 선량분포를 계산된 선량분포 위에서 lmm 간격으로 이동시켜가면서 선량의 차이를 계산하여 이 값이 최소가 되는 위치를 확인한다. 이때의 이동치는 가속기가 갖는 허용오차 이내에 있어야 하며 이 값은 2mm로 알려져 있다. 이 과정과는 독립적으로 이온 챔버를 통해 측정된 절대선량 값을 이용하여 두 선량분포 사이를 재 규격화한 뒤 차이를 구하게 되면 우리는 5mm 간격의 2 차원 절대선량 분포 비교를 실험상의 오차들 중 가장 크게 작용하는 원점 오차로 인한 오차를 제거한 뒤 수행한 것과 같은 결과를 얻게 된다. 여기서 계산된 선량분포의 해상도는 장비의 허용오차 보다 항상 작아야 한다. 결과 : 머리와 목에 환부를 갖는 여러 환자들에 대한 선량분포 비교 결과를 통해서, 측정된 선량분포와 계산된 선량분포사이의 허용오차 범위에 대한 일시적 기준을 마련하였다. 이 기준은 물론 더 많은 환자들에 대한 선량분포 비교를 통해 개선되어질 수 있다. 결론 : 측정 장비의 원점 불일치의 보정뿐만 아니라 측정 장비의 회전에 의한 오차 보정, 필름의 광학적 밀도에 관한 보정 등 여러 가지 계통적 오차들에 대한 보정들이 선량분포 확인과정의 이해와 그 기준마련에 도움이 되겠지만 우리가 다룬 원점 불일치에 비해서 상대적으로 무시할 수 있었다. 마지막으로 선량분포 확인의 최종목표인 3 차원 선량분포 확인의 실제 적용을 위한 연구가 최적화 알고리듬을 이용하여 실험 중에 있다.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.357-363
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• 2011

The aim of this study is to compare radiation dose in diagnostic X-ray radiography and calculated by different mathematical equation. The result of ESDs direct measurement and that calculated by Mori NDD-M shows the biggest difference. On the other hand, equation by Edmonds shows the lowest difference of ESDs. Also, Rectification due to the difference between direct dose measurement and calculation method commutated three-phase, single phase and inverter type, show less difference in the drive way. In conclusion, this study can be helpful for expecting radiation dose-exposure and control exposure parameters for the diagnostic x-ray radiography.

• Progress in Medical Physics
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• v.17 no.2
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• pp.114-122
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• 2006

The two commonly used methods in delivering intensity modulated radiation therapy (IMRT) plan are the dynamic (sliding window) and static (stop and shoot) mode. In this study, the two IMRI delivery techniques are compared by measuring point dose and dose distributions. Using treatment planning system, clinical target volume (CTV) was created as a sphere with various diameter (3 cm, 7 cm, 12 cm). Two IMRT plans were peformed to deliver 200 cGy to the CTV in dynamic and static mode. The two plans were delivered on a phantom and central point dose and dose distributions were measured. The central point dose differences between static and dynamic IMRT delivery were 0.2%, 0.2% and 0.4% when the diameter of CTV was 3 cm, 7 cm, and 12 cm, respectively. The differences In volume receiving 90% of the proscribed dose were 2.7%, 2.2%, and 2.9% for the diameter of CTV was 3 cm, 7 cm, and 12 cm, respectively. For lung cancer patients, the differences in central point dose were 0.2%, 0.2%, and 0.4% when the volume of CTV was 35.5 cc, 296.8 cc, and 903.5 cc, respectively. The differences in volume receiving 90% of the prescribed dose were 2.7%, 4.8%, and 9.1% when the volume of CTV was 35.5 cc, 296.8 cc, and 903.5 cc, respectively. In conclusion, it was possible to deliver IMRT plans using dynamic mode of MLC operation although the loaves are In motion during radiation delivery.

• Progress in Medical Physics
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• v.19 no.1
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• pp.9-13
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• 2008

The purpose of this study was to measure the skin dose using the glass dosimeter and diode and to compare those measurements to the planned skin dose from the treatment planning system. For the reproducibility of the glass dosimeter (ASAHI TECHNO GLASS CIRPORATION, Japan), the same dose was irradiated to 40 glass dosimeters three times, among which 28 with the reproducibility within 3% were selected for the use of this study. For each of 27 breast cancer patients, the glass dosimeters and diodes were attached to 4 different locations on the skin to measure the dose during treatment. All the patients received one fraction of 180 cGy each. The maximum difference of measurements between the glass dosimeter and diode at the same location was 3.2%. Comparing with the planned skin dose from the treatment planning system (Eclipse v6.5, Varian, USA), the dose measured by the glass dosimeter and the diodeshowed on an average 3.4% and 2.3% difference, respectively. The measured doses were always less than the planned skin dose. This may be due to the specific errors of both detectors. Also, the difference may be caused by the fact that since the skin where the detectors were attached is pretty moveable, it was not fix the detectors on the skin.

• Journal of radiological science and technology
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• v.30 no.4
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• pp.381-389
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• 2007

The purpose of this study is investigation of radiation dose in CT scan. Data were collected from various references and organizations. Doses measured by CT scanners of each medical organization were analyzed and they were calculated through the examination protocol. The results are as follows : 1. $CTDI_W$ value per 100mAs measured by Head Phantom was the highest in <4-slice MDCT scanner> of 24.20 mGy. $CTDI_W$ values were significantly different among scanner generations(p < 0.01). 2. $CTDI_W$ value per 100 mAs measured using body phantom was the highest in <4-slice MDCT scanner> of 13.58 mGy and the $CTDI_W$ values were significantly different among scanner generations(p < 0.01). 3. When contrast medium was not used, the highest scanner was <16 slice MDCT> of $818.83\;mGy{\codt}cm$ in exposure dose in brain scan(p < 0.05). When the contrast medium was used, the highest scanner was <4 slice MDCT> and its average was $1,460.77\;mGy{\cdot}cm$(p < 0.1). 4. When the contrast medium was not used, the highest scanner was <16-slice MDCT> of $521.63\;mGy{\cdot}cm$ on average in terms of the exposure dose in chest inspection(p<0.05). when the contrast medium was used, the highest scanner was found in 8 slice MDCT scanner and its average was $1,174.70\;mGy{\cdot}cm$. There was no statistically significant difference among scanners. 5. When the contrast medium was not used, the highest scanner was <16-slice MDCT> and its average was $856.27\;mGy{\cdot}cm$ in exposure dose on the abdomen-pelvis(p<0.05). when the contrast medium was used, the highest scanner was <16-slice MDCT> and its average was $1,720.64\;mGy{\cdot}cm$ on average (p < 0.05). 6. When the contrast medium was not used, the highest scanner was <8-slice MDCT> and its average was $612.07\;mGy{\cdot}cm$ in exposure dose in liver inspection(p < 0.05). when the contrast medium was used, the highest scanner was <8-slice MDCT scanner> and its average was $2,197.93\;mGy{\cdot}cm$ in exposure dose(p < 0.1). seventy six point two percent of medical facilities were in risk of radiation exposure while the number of phase was three to four times in their dose inspection of contrast medium.

• Progress in Medical Physics
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• v.9 no.3
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• pp.175-184
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• 1998

The dose distribution evaluation program for the stereotactic radiosurgery treatment planning system using a gamma knife has been built in order to work on PC. And this custom-made dose distribution is compared with that of commercial treatment planning program. 201 source position of a radiation unit were determined manually using a gamma knife collimator draft and geometrical coordinates. Dose evaluation algorithm was modified for our purpose from the original KULA, a commercial treatment planning program. With the composed program, dose distribution at the center of a spherical phantom, 80 mm in diameter, was evaluated into axial, coronal and sagittal image per each collimator. Along with this evaluated data, the dose distribution at a arbitrary point of inside the phantom was compared with those from KULA. Radiochromic film was set up at the center of the phantom and was irradiated by gamma knife, for the verification of dose distribution. In result, the deviation of the dose distribution from that of KULA is less than ${\pm}$3%, which is equivalent to ${\pm}$0.3 mm in 50% isodose distribution for all examined coordinates and film verification. The custom-made program, GPl is proven to be a good tool for the stereotactic radiosurgery treatment planning program.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.149-152
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• 2004

물 흡수선량 표준에 토대를 두고 있는 프로토콜에서는 저에너지 전자선의 경우 평행평판형이온함의 사용과 기준 선질 $^{60}$CO 감마선의 물 흡수선량 교정정수를 받은 원통형이온함을 사용하여 고에너지 전자선에서 평행평판형이온함을 교차교정하도록 권고하고 있다. 따라서 본 연구에서는 국제원자력기구의 프로토콜(IAEA TRS-398)에서 권고하고 있는 절차에 따라 저에너지 전자선에 대한 원통형이온함의 선질보정정수를 계산하고, 원통형이온함과 평행평판형이온함의 교정방법에 따른 흡수선량을 상호 비교하였다. 그 결과 전자선에너지 10 MeV 이상에서는 두 이온함간의 선량이 잘 일치하였으나 전자선에너지 6, 9 MeV에서 최대 3.3%까지 선량 차이를 보여 저에너지 전자선에서는 반드시 평형판판형이온함의 사용하여 선량측정 할 것을 권고한다. 교정방법 차이에 의한 평행평판형이온함의 선량은 서로 잘 일치하는 것으로 나타나 표준기관에서 직접 교정받은 $^{60}$Co 감마선의 물 흡수선량교정정수를 사용하여 전자선 물 흡수선량을 결정해도 큰 영향은 없을 듯하다. 또한 평행평판형이온함을 교차 교정하기 위한 전자선 에너지에 따른 흡수선량을 상호 비교한 결과 20MeV이외 12, 16 MeV의 전자선 에너지에서도 잘 일치하여 교차교정을 위한 전자선의 기준 선질에 대한 연구가 더 진행되어야 한다고 사료된다.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.1
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• pp.59-67
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• 2014

Purpose : This study aims to evaluate 3D dosimetric impact for MIP image and each phase image in stereotactic body radiotherapy (SBRT) for lung cancer using volumetric modulated arc therapy (VMAT). Materials and Methods : For each of 5 patients with non-small-cell pulmonary tumors, a respiration-correlated four-dimensional computed tomography (4DCT) study was performed. We obtain ten 3D CT images corresponding to phases of a breathing cycle. Treatment plans were generated using MIP CT image and each phases 3D CT. We performed the dose verification of the TPS with use of the Ion chamber and COMPASS. The dose distribution that were 3D reconstructed using MIP CT image compared with dose distribution on the corresponding phase of the 4D CT data. Results : Gamma evaluation was performed to evaluate the accuracy of dose delivery for MIP CT data and 4D CT data of 5 patients. The average percentage of points passing the gamma criteria of 2 mm/2% about 99%. The average Homogeneity Index difference between MIP and each 3D data of patient dose was 0.03~0.04. The average difference between PTV maximum dose was 3.30 cGy, The average different Spinal Coad dose was 3.30 cGy, The average of difference with $V_{20}$, $V_{10}$, $V_5$ of Lung was -0.04%~2.32%. The average Homogeneity Index difference between MIP and each phase 3d data of all patient was -0.03~0.03. The average PTV maximum dose difference was minimum for 10% phase and maximum for 70% phase. The average Spain cord maximum dose difference was minimum for 0% phase and maximum for 50% phase. The average difference of $V_{20}$, $V_{10}$, $V_5$ of Lung show bo certain trend. Conclusion : There is no tendency of dose difference between MIP with 3D CT data of each phase. But there are appreciable difference for specific phase. It is need to study about patient group which has similar tumor location and breathing motion. Then we compare with dose distribution for each phase 3D image data or MIP image data. we will determine appropriate image data for treatment plan.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.329-334
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• 2012

For the dosimetry of the radiation workers, film badge, Thermo Luminescent Dosimeter (TLD), and glass dosimeter are being used and recently, there is a growing trend of using Optically Stimulated Luminescence Dosimeter (OSLD) in the world. However, OSLD is only being applied some of the field in Korea and there has been almost no study made related to OSLD. Thus, the accumulated radiation dose of TLD and OSLD that have been most frequently used in the field was compared in the radiation workers of nuclear medicine and their working areasfor 3 months. As a result, the average surface dose showed 0.85 mSv difference with 1.27 mSv for TLD and 2.12 mSv for OSLD while having 0.73 mSv difference for the average depth dose with 1.33 mSv for TLD and 2.06 mSv for OSLD. The surface dose and depth dose of OSLD showed statistically significant result with higher measurement (p<0.05).

• Radiation Oncology Journal
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• v.5 no.2
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• pp.137-140
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• 1987

In brachytherapy of uterine conical cancer using a high dose rate remote afterloading system, it is of prime importance to deliver a accurate dose in each fractionated treatment by minimizing the difference between the pre-treatment planned and post-treatment calculated doses. The post-treatment calculated point A dose was not much different from the pretreatment planned dose (500 cGy). The $average{\pm}standard$ deviation was $500\pm18cGy$ and 84 percent of 82 intracavitary radiotherapy was within the range of $500\pm25cGy$.