• 한국자기학회지
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• 제26권3호
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• pp.99-104
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• 2016

항암요법과 방사선치료를 병행하여 두경부암을 치료하는 환자의 경우 항암요법과 방사선치료를 거듭할수록 구토, 메스꺼움, 식욕부진 등의 이유로 환자의 체중 감소가 생기게 된다. 체중 감소는 목의 두께 변화로 나타날 수 있으며 이로 인해 치료하고자 하는 t 타겟과 주위 정상조직의 선량 전달에도 영향을 미치며 방사선이 전달되는 방향에 위치한 피부선량의 변화가 나타날 것으로 사료된다. 특히 비인두암 환자의 경우 비인두 구조가 다른 장기보다 복잡한 구조를 지니고 있고 치료방법인 토모테라피는 수 mm 차이로 급격한 선량 변화가 발생하므로 이러한 체중 감소의 변화에 주의 깊은 관찰이 필요하다. 현재 토모테라피의 경우 매 회 치료 전 정확한 자세 재현을 위한 영상 검증을 통해 이러한 움직임을 확인하고 그 값을 보정하여 치료를 수행한다. 그러나 환자의 체중 감소로 인하여 피부선량에 전달되는 선량 변화의 검증은 되지 않고 있다. 환자의 피부선량이 증가함으로써 나타나는 부작용은 환자의 삶의 질에 영향을 미칠 뿐 만 아니라 2차 암 발생률을 높일 수 있다. 이에 환자의 체중 감소로 인하여 나타나는 환자의 목 두께를 휴먼 팬톰에 볼루스를 올리고 두께를 조절해가며 변화시켜 필름을 이용하여 피부선량의 변화가 어떻게 나타나는지 분석해보고자 한다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.215-221
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• 2023

Proton treatment may deliver a larger dose to a patient's skin than traditional photon therapy, especially when a range shifter (RS) is inserted in the beam path. This study investigated the effects of an RS on skin dose while considering RS with different thicknesses, airgaps and materials. First, the physical model of the scanning nozzle with RS was established in the TOol for PArticle Simulation (TOPAS) code, and the effects of the RS on the skin dose were studied. Second, the variations in the skin dose and isocenter beam size were examined by reducing the air gap. Finally, the effects of different RS materials, such as polymethylmethacrylate (PMMA), Lexan, polyethylene and polystyrene, on the skin dose were analysed. The results demonstrated that the current RS design had a negligible effect on the skin dose, whereas the RS significantly impacted the isocenter beam size. The skin dose was increased considerably when the RS was placed close to the phantom. Moreover, the magnitude of the increase was related to the thickness of the inserted RS. Meanwhile, the results also revealed that the secondary proton primarily contributed to the increased skin dose.

• 대한방사선기술학회지:방사선기술과학
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• 제25권2호
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• pp.35-38
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• 2002

의료피폭에 관한 관심과 함께 촬영록(촬영조건)을 기록하는 일은 단순히 환자기록이 아니라 피폭선량을 예측하는 방법으로 이용될 수 있다. 그러나 각 장비마다 출력의 차이가 있어서 장치의 출력을 실험을 통하여 구하고 그 출력을 엑셀 프로그램상에서 3차 수식화하여 그 계수를 구함으로서 촬영조건을 입력함과 동시에 피부 입사선량을 구할 수 있는 방법을 고안하였다.

• 대한방사선기술학회지:방사선기술과학
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• 제30권1호
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• pp.7-12
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• 2007

위암은 $1999{\sim}2001$년 국내 암발생율 1위로 조기진단이 중요시 된다. 위암의 검사방법 중 하나인 위장 X선 투시검사는 중요성이 높기 때문에 저자 등은 인천지역을 중심으로 종합 대학병원, 병원, 개인의원급 21대의 X선장치를 선정하여 X선장치의 현황과 투시검사 및 저격촬영시의 검사조건 등을 조사하였다. 또한 검사중 환자표면선량을 전리조를 이용하여 측정하였다. 본 연구는 위장 X선 투시검사의 실태 및 환자표면선량의 정도를 파악하여 그 현황을 알리고자 실시하였다.

• Radiation Oncology Journal
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• 제35권2호
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• pp.121-128
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• 2017

Purpose: To report the results of a correlation analysis of skin dose assessed by in vivo dosimetry and the incidence of acute toxicity. This is a phase 2 trial evaluating the feasibility of intraoperative radiotherapy (IORT) as a boost for breast cancer patients. Materials and Methods: Eligible patients were treated with IORT of 20 Gy followed by whole breast irradiation (WBI) of 46 Gy. A total of 55 patients with a minimum follow-up of 1 month after WBI were evaluated. Optically stimulated luminescence dosimeter (OSLD) detected radiation dose delivered to the skin during IORT. Acute toxicity was recorded according to the Common Terminology Criteria for Adverse Events v4.0. Clinical parameters were correlated with seroma formation and maximum skin dose. Results: Median follow-up after IORT was 25.9 weeks (range, 12.7 to 50.3 weeks). Prior to WBI, only one patient developed acute toxicity. Following WBI, 30 patients experienced grade 1 skin toxicity and three patients had grade 2 skin toxicity. Skin dose during IORT exceeded 5 Gy in two patients: with grade 2 complications around the surgical scar in one patient who received 8.42 Gy. Breast volume on preoperative images (p = 0.001), ratio of applicator diameter and breast volume (p = 0.002), and distance between skin and tumor (p = 0.003) showed significant correlations with maximum skin dose. Conclusions: IORT as a boost was well-tolerated among Korean women without severe acute complication. In vivo dosimetry with OSLD can help ensure safe delivery of IORT as a boost.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.229-236
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• 2016

Background: In order to manage the patient exposure dose in X-ray diagnosis, it is preferred to evaluate the entrance skin dose; although there are some evaluations about entrance skin dose, a small number of report has been published for direct measurement of patient. We think that a small-type optically stimulated luminescence (OSL) dosimeter, named nanoDot, can achieve a direct measurement. For evaluations, the corrections of angular and energy dependences play an important role. In this study, we aimed to evaluate the angular and the energy dependences of nanoDot. Materials and Methods: We used commercially available X-ray diagnostic equipment. For angular dependence measurement, a relative response of every 15 degrees of nanoDot was measured in 40-140 kV X-ray. And for energy dependence measurement, mono-energetic characteristic X-rays were generated using several materials by irradiating the diagnostic X-rays, and the nanoDot was irradiated by the characteristic X-rays. We evaluated the measured response in an energy range of 8.1-75.5 keV. In addition, we performed Monte-Carlo simulation to compare experimental results. Results and Discussion: The experimental results were in good agreement with those of Monte-Carlo simulation. The angular dependence of nanoDot was almost steady with the response of 0 degrees except for 90 and 270 degrees. Furthermore, we found that difference of the response of nanoDot, where the nanoDot was irradiated from the randomly set directions, was estimated to be at most 5%. On the other hand, the response of nanoDot varies with the energy of incident X-rays; slightly increased to 20 keV and gradually decreased to 80 keV. These results are valuable to perform the precise evaluation of entrance skin dose with nanoDot in X-ray diagnosis. Conclusion: The influence of angular dependence and energy dependence in X-ray diagnosis is not so large, and the nanoDot OSL dosimeter is considered to be suitable dosimeter for direct measurement of entrance surface dose of patient.

• 대한방사선치료학회지
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• 제32권
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• pp.85-92
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• 2020

목 적: 열가소성(thermoplastic) bolus가 가지는 이점을 알아보고자 이를 사용하여 치료한 두 건의 case를 선량과 위치 재현성 측면으로 나누어 피부 병변 VMAT 치료에서의 열가소성 bolus의 유용성을 평가하였다. 대상 및 방법: 좌측 유방 피부 병변 치료 환자 두 명을 대상으로 열가소성 Bolus를 사용하여 simulation 하였고 2 arc VMAT으로 계획하였다. 각 치료 계획은 처방선량(Prescription dose)이 표적 체적의 95% 이상 조사되도록 설계하였다. CBCT(Cone Beam CT) 영상에서 air gap의 길이를 측정하여 bolus 위치의 재현성을 평가하였다. 선량의 재현성을 평가하기 위해 Plan에서의 선량 분포와 CBCT에서의 선량 분포를 비교하였고 환자 2에 대해 in vivo 측정을 하였다. 결 과: 환자 1의 치료계획용 CT에서의 air gap과 CBCT image에서 10회 치료 동안 생긴 평균 air gap(M1)의 차이는 -0.42±1.24mm였다. 환자 2에서 14회 치료 동안 생긴 skin과 bolus 사이의 평균 air gap(M2)과 치료계획용 CT의 air gap의 차이는 -1.08±1.3mm, 두 bolus 사이의 air gap(M3)과의 차이는 0.49±1.16으로 나타났다. 치료계획용 CT와 CBCT의 선량 분포 차이는 환자 1에서 PTV1 D95가 -1.38%, Skin(max)가 0.39%의 차이를 보였고 환자 2에서 PTV1 D95가 0.63%, SKIN(max)가 -0.53%의 차이를 나타내었다. in vivo 측정 결과 계획된 선량과 -1.47% 차이를 보였다. 결 론: 열가소성 Bolus는 3D printer로 제작한 것과 비교하여 제작 과정이 단순하고 소요 시간이 길지 않으며, set up 측면에서 재현성 있는 결과를 보였고 선량 측면에서도 안정적인 결과를 나타내어 불규칙한 표면의 피부 병변 치료에서 그 유용성이 높은 것으로 사료된다.

• 한국콘텐츠학회논문지
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• 제11권9호
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• pp.437-442
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• 2011

본 연구의 목적은 진단방사선촬영의 X-선 빔 조사 조건하에서 광자극발광선량계를 사용하여 환자의 피부선량을 측정하는 것이다. 피부선량의 측정은 머리, 가슴, 골반에 대하여 실시하고 재현성의 시험은 가슴에서 시행하였다. 그 결과 머리는 이마에서 피부선량 1.30 mSv의 값을 얻었으며 가슴은 검상돌기, 유방, 폐첨에서 각각 0.92, 0.52, 0.70 mSv의 값을 얻었다. 또한 골반은 좌측골반과 우측골반에서 피부선량 각각 2.78, 3.08 mSv의 값을 얻었다. 재현성은 변동계수로서 0.033을 얻었다. 피부선량들은 결정적 영향에서 일반인의 선량한도(50 mSv)의 1/100에서 1/17에 대응하는 값들을 나타냈다. 각 관전압에 대한 피부선량의 정확한 측정을 위하여 측정값은 판독장치의 표시값에 보정인자를 곱해야 한다. 이에 향후에는 관전압에 대한 에너지의존성의 연구가 진행되어야 할 것으로 사료된다.

• 한국의학물리학회지:의학물리
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• 제28권1호
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• pp.33-38
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• 2017

Creating individualized build-up material for superficial photon beam radiation therapy at irregular surface is complex with rice or commonly used flat shape bolus. In this study, we implemented a workflow using 3D printed patient specific bolus and describe our clinical experience. To provide better fitted build-up to irregular surface, the 3D printing technique was used. The PolyLactic Acid (PLA) which processed with nontoxic plant component was used for 3D printer filament material for clinical usage. The 3D printed bolus was designed using virtual bolus structure delineated on patient CT images. Dose distributions were generated from treatment plan for bolus assigned uniform relative electron density and bolus using relative electron density from CT image and compared to evaluate the inhomogeneity effect of bolus material. Pretreatment QA is performed to verify the relative electron density applied to bolus structure by gamma analysis. As an in-vivo dosimetry, Optically Stimulated Luminescent Dosimeters (OSLD) are used to measure the skin dose. The plan comparison result shows that discrepancies between the virtual bolus plan and printed bolus plan are negligible. (0.3% maximum dose difference and 0.2% mean dose difference). The dose distribution is evaluated with gamma method (2%, 2 mm) at the center of GTV and the passing rate was 99.6%. The OSLD measurement shows 0.3% to 2.1% higher than expected dose at patient treatment lesion. In this study, we treated Mycosis fungoides patient with patient specific bolus using 3D printing technique. The accuracy of treatment plan was verified by pretreatment QA and in-vivo dosimetry. The QA results and 4 month follow up result shows the radiation treatment using 3D printing bolus is feasible to treat irregular patient skin.

• 대한방사선기술학회지:방사선기술과학
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• 제15권1호
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• pp.79-87
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• 1992

It is a matter of common knowledge that madical radiation is most accented for of radiation is doses applied to the whole of people, and of them the radation dose by radiography diagnosis is mainly prevalent. In applying X-rays to a certain man for radiography diagnosis a radiologyist will have to have an absolute sense of mission concerning the reduction and prevention of the patient's radiation dose as the radiologyist obligation. Accordingly, the radiography conditions of the patient's chest employed 197 medical facilites were surveyed and skin dose was computated by the IPH Bit system and examined. As a result, it was shown that the average skin dose was $288\;{\mu}Sv$, its minimum value was $1600\;{\mu}Sv$, which was over 32 times its minimum value. This shows that the appropriate radiography method has not been applied at applying X-ray to the patient. It comes from the performance of X-ray equipment, the choice of auxiliary equipment materials etc. But the most important thing is to master the appropriate radiography condition, and therefore this point will have to be kept in mind.