Radiation Oncology Journal

The Korean Society for Radiation Oncology (대한방사선종양학회)
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Comparison of the Dose of the Normal Tissues among Various Conventional Techniques for Whole Brain Radiotherapy

여러 통상적인 전뇌방사선치료 기법에서의 정상조직의 조사선량 비교

  • Kang, Min-Kyu (Department of Radiation Oncology, Yeungnam University College of Medicine)
  • 강민규 (영남대학교 의과대학 방사선종양학교실)
  • Received : 2009.12.21
  • Accepted : 2010.04.19
  • Published : 2010.06.30
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Abstract

Purpose: To compare radiation dose of the brain and lens among various conventional whole brain radiotherapy (WBRT) techniques. Materials and Methods: Treatment plans for WBRT were generated with planning computed tomography scans of 11 patients. A traditional plan with an isocenter located at the field center and a parallel anterior margin at the lateral bony canthus was generated (P1). Blocks were automatically generated with a 1 cm margin on the brain (5 mm for the lens). Subsequently, the isocenter was moved to the lateral bony canthus (P2), and the blocks were replaced into the multileaf collimator (MLC) with a 5 mm leaf width in the craniocaudal direction (P3). For each patient plan, 30 Gy was prescribed at the isocenter of P1. Dose volume histogram (DVH) parameters of the brain and lens were compared by way of a paired t-test. Results: Mean values of $D_{max}$ and $V_{105}$ of the brain in P1 were 111.9% and 23.6%, respectively. In P2 and P3, $D_{max}$ and $V_{105}$ of the brain were significantly reduced to 107.2% and 4.5~4.6%, respectively (p<0.001). The mean value of $D_{mean}$ of the lens was 3.1 Gy in P1 and 2.4~2.9 Gy in P2 and P3 (p<0.001). Conclusion: WBRT treatment plans with an isocenter located at the lateral bony canthus have dosimetric advantages for both the brain and lens without any complex method changes.

목 적: 여러 통상적인 전뇌방사선치료 기법에서의 뇌와 수정체의 방사선 조사선량을 비교하고자 하였다. 대상 및 방법: 전뇌방사선치료를 위한 치료계획을 11명의 환자를 대상으로 컴퓨터단층촬영 영상을 이용하여 다음과 같이 수립하였다. 중심점이 조사영역의 중앙에 위치하고 가쪽눈구석(lateral bony canthus)에서 양측 빔이 평행한 통상적인 계획을 수립하고, 뇌에서 1 cm (렌즈에 대해서는 5 mm)의 여유로 차폐물을 생성하였다(P1). 이후 중심점을 가쪽눈구석으로 옮기고(P2), 조준기를 90도 회전시킨 후 5 mm 두께의 다엽조준기로 차폐를 하였다(P3). 각 환자의 모든 계획에서 P1의 중심점에 30 Gy를 처방하였다. 뇌와 수정체의 선량 지표들은 paired t-test를 이용하여 비교하였다. 결 과: 뇌의 $D_{max}$와 $V_{105}$는 P1에서 111.9%와 23.6%였다. 뇌의 $D_{max}$와 $V_{105}$는 P2와 P3에서 유의하게 감소하였는데, 그 값은 각각 107.2%와 4.5~4.6%였다(p<0.001). 수정체의 $D_{mean}$의 평균값은 P1에서 3.1 Gy, P2와 P3에서는 2.4~2.9 Gy였다(p<0.001). 결 론: 전뇌방사선치료 시 다른 복잡한 방법을 이용하지 않고, 중심점을 가쪽눈구석에 위치시키는 것만으로도 뇌와 수정체의 조사선량 측면에서 유리하였다.

Keywords

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