Reduction of Electron Contamination Using a Filter for 6MV Photon Beam

이철수(Choul Soo Lee),유명진(Myung Jin Yoo),염하용(Ha Yong Yum) 대한방사선종양학회 1997 Radiation Oncology Journal Vol.15 No.2

목 적 : 광자선과 블록을 얹는 트레이와의 상호작용에 의해 생성된 2차 전자는 피하층에 과도한 선량증가의 원인이 된다. 이런 전자오염으로 인한 표면선량을 감소시키기 위해 트레이 아래 전자필터를 부착하는 것이 유용하다. 대상 및 방법 : 두께가 다른 Cu판, Al판 그리고 Cu/Al 복합판을 사용하여 전자오염에 의한 표면선량을 감소시키는 효과를 측정하였다. 최적의 필터를 찾기 위해서 10cm×10cm 조사야와 SSD 78.5cm의 기하학적 모형으로 표면에서부터 최대선량 지점까지 2mm 간격으로 흡수선량을 측정하였다. 최적필터의 조사야 의존성을 구하기 위해서 4cm×4cm에서부터 25cm×25cm까지 조사면적을 변화시켜가며 흡수선량을 측정하였다. 결 과 : 표면선량은 조사면적을 증가시키면 서서히 증가하였고 15cm×15cm 조사면적 이상에서는 표면선량이 급속히 증가하였다. Al판을 사용했을 경우 표면선량이 최대선량 지점의 선량보다 낮게 유지되지 않으므로 Al판은 전자필터로는 부적합하였으며 0.5mm Cu판과 Cu/Al=0.28mm/1.5mm 복합판이 최적 전자필터로 결정되었다. 두가지 최적필터의 경우 4cm×4cm 조사면에서는 표면선량을 5.5%(tray 사용할때 표면선량에서 filter 사용할때 표면선량을 뺀 것) 낮출 수 있었고 10cm×10cm에서는 11.3%, 25cm×25cm에서는 21.3%로 낮출 수 있었다. 결 론 : 전자오염에 기인한 표면선량은 조사면적에 의존하였고 트레이를 설치했을때 표면의 전자오염은 많았고 특히 조사면적이 클 때 표면의 전자오염은 더욱 증가하였다. 표면 및 build-up 영역의 선량 특성을 측정한 결과 0.5mm Cu판과 Cu/Al=0.28mm/1.5mm 복합판이 최적 필터로 결정되었다. 트레이 밑에 최적 필터를 부착하면 표면선량을 유효하게 감소시킬 수 있었고 필터의 효과는 조사면적이 클 때 더욱 좋았다. Purpose : Secondary electrons generated by interaction between primary X-ray beam and block tray in megavoltage irradiation, result in excess soft radiation dose to the surface layer. To reduce the surface dose from the electron contamination, electron filters were attached under the tray when a customized block was used. Materials and Methods : Cu, Al or Cu/Al combined plate with different thickness was used as a filter and the surface dose reduction was measured for each case. The measurement to find optimal filter was performed with 10cm×10cm field size and 78.5cm source to surface distance. The measurement points are positioned with 2mm intervals from surface to maximum build-up point. To acquire the effect of field size dependence on optimal electron filter, the measurement was performed from 4cm×4cm to 25cm×25cm field sizes. Results : The surface dose was slowly increased by increasing irradiation field but rapidly increased beyond 15cm×15cm field size. Al plate was found to be inadequate filter because of the failure to have surface dose kept lowering than the dose of deep area. Cu 0.5mm plate and Cu/Al= 0.28mm/1.5mm combined plate were found to be optimal filters. By using these 2 filters, the absorbed dose to the surface layer was effectively reduced by 5.5%, 11.3%, and 22.3% for the field size 4cm×4cm, 10cm×10cm, and 25cm×25cm, respectively. Conclusion : The surface dose attributable to electron contamination had a dependence on field size. The electron contamination was increased when tray was used. Specially the electron contamination in the surface layer was greater when the larger field was used. 0.5mm Cu plate and Cu/Al=0.28mm/1.5mm combined plates were selected as optimal electron filters. When the optimal electron filter was attached under the tray, excessive surface dose was decreased effectively. The effect of these electron filters was better when a larger field was used.

방사선 치료 관련 정보에 대안 환자의 이해정도 및 교육요구도

강수만,이철수,Kang, Soo-Man,Lee, Choul-Soo 대한방사선치료학회 2006 대한방사선치료학회지 Vol.18 No.2

The purpose of this study is to understand preliminary education. level of understanding and the degrees of educational requirement for cancer patients on radiotherapy and to present the preliminary data to development of effective and practical patients treatment programs. Based on the abovementioned results of this study. Relationship betweendegrees of knowledge and demand for educational requirement for patients who are undertaking radiotherapy could be varied with different factors such as educational background, ages, regions of treatment, experience of symptoms. In general, patients do not have enough information, on the other hand, have very high demand for educational requirement. Customized education patients by patients would not be possible in reality. However, if we could provide standard for patients and establish systematic sessions during treatment based on this study, more and better patients satisfaction and results of treatments could be achieved.

선형가속기 10 MV 광자선에서 산란판(Beam Spoiler) 사용 시 표면선량 변화

배성철,김준호,이철수,Bae, Seong-Cheol,Kim, Jun-Ho,Lee, Choul-Soo 대한방사선치료학회 2006 대한방사선치료학회지 Vol.18 No.1

Purpose: The purpose of this study is to find a optimal beam spoiler condition on the dose distribution near the surface, when treating a squamous cell carcinoma of the head and neck and a lymphatic region with 10 MV photon beam. The use of a optimal spoiler allows elivering high dose to a superficial tumor volume, while maintaining the skin-sparing effect in the area between the surface to the depth of 0.4 cm. Materials and Methods: The lucite beam spoiler, which were a tissue equivalent, were made and placed between the surface and the photon collimators of linear accelerator. The surface-dose, the dose at the depth of 0.4 cm, and the maximum dose at the dmax were measured with a parallel-plate ionization chamber for $5{\times}5cm\;to\;30{\times}30cm^2$ field sizes using lucite spoilers with different thicknesses at varying skin-to-spoiler separation (SSS). In the same condition, the dose was measured with bolus and compared with beam spoiler. Results: The spoiler increased the surface and build-up dose and shifted the depth of maximum dose toward the surface. With a 10 MV x-ray beam and a optimal beam spoiler when treating a patient, a similer build-up dose with a 6 MV photon beam could be achieved, while maintaining a certain amount of skin spring. But it was provided higher surface dose under SSS of less than 5 cm, the spoiler thickness of more than 1.8 cm or more, and larger field size than $20{\times}20cm^2$ provided higher surface dose like bolus and obliterated the spin-sparing effect. the effects of the beam spoiler on beam profile was reduced with increasing depths. Conclusion: The lucite spoiler allowed using of a 10 MV photon beam for the radiation treatment of head and neck caner by yielding secondary scattered electron on the surface. The dose at superficial depth was increased and the depth of maximum dose was moved to near the skin surface. Spoiling the 10 MV x-ray beam resulted in treatment plans that maintained dose homogeneity without the consequence of increased skin reaction or treat volume underdose for regions near the skin surface. In this, the optimal spoiler thickeness of 1.2 cm and 1.8 cm were found at SSS of 7 cm for $10{\times}10cm^2$ field. The surface doses were measured 60% and 64% respectively. In addition, It showed so optimal that 94% and 94% at the depth of 0.4 cm and dmax respectively.

계획요소를 통한 대도시 수변공간 도시재생프로젝트의 비교분석

서은영(Seo, Eun-Young),이철수(Lee, Choul-Soo),원제무(Won, Jai-Mu) 대한국토·도시계획학회 2012 國土計劃 Vol.47 No.6

파형강관 케이싱 현장타설말뚝의 시공과 수평재하시 안정성 평가

조성민(Cho Sung-Min),전병섭(Jeon Byeong Seob),김수철(Kim Soo-Chul),이철수(Lee Choul Soo),최고일(Choi Ko Il) 대한토목학회 2007 대한토목학회 학술대회 Vol.2007 No.10

노인요양시설 평가지표 개발 및 적용에 관한 연구

최형선 ( Hyoung Sun Choi ),서은영 ( Eun Young Seo ),이철수 ( Choul Soo Lee ),원제무 ( Jai Mu Won ) 한국부동산분석학회 2012 不動産學硏究 Vol.18 No.4

Increasing attentions have recently paid to elderly care facilities due to the inadequate service facilities, such as internal spaces, road and parking, environment. In this regard, this study aims to develop evaluation indicators that can be used to evaluate the 5 elderly care facilities. Five elderly care facilities were examined according to evaluation indicators. Most of the elderly care facilities suffer from the inadequate internal spaces, road and parking, accessibility and environment. The results of research show that safety of elderly life turned out to be the most critical factors. Thus, Safety-related factors should be given high priority in designing elderly care facilities. This study can be used to provide guidelines for improving elderly care facilities.