The Journal of Korean Society for Radiation Therapy (대한방사선치료학회지)

Korean Society for Radiation Therapy (대한방사선치료학회)
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Comparison of dose-variation in skin due to Set-up error in case of radiation therapy for left breast using Volumetric Modulated Arc Therapy(VMAT)

좌측 유방에 대한 용적 변조 회전 방사선 치료 시 자세 오차로 인한 피부 선량

  • Kwon, Yongjae (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center) ;
  • Park, Ryeunghwang (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center) ;
  • Kim, Seyoung (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center) ;
  • Jung, Dongmin (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center) ;
  • Baek, Jonggeol (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center) ;
  • Cho, Jeonghee (Department Of Radiation Oncology, Yonsei University Yonsei Cancer Center)
  • 권용재 (연세암병원 방사선종양학과) ;
  • 박령황 (연세암병원 방사선종양학과) ;
  • 김세영 (연세암병원 방사선종양학과) ;
  • 정동민 (연세암병원 방사선종양학과) ;
  • 백종걸 (연세암병원 방사선종양학과) ;
  • 조정희 (연세암병원 방사선종양학과)
  • Published : 2021.12.31
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Abstract

Purpose: This study aims to contribute to the reduction of complications of breast cancer radiation therapy by analyzing skin dose differences due to Set-up error. Materials and Method: Pseudo breast was produced using a 3D printer, applied to the phantom, and images were acquired through CT. Treatment plan was carried out that the PTV, which contains 95% of the prescription dose, could be more than 95% of the volume, so that Dmax did not exceed 107% of the prescription dose. The Set-up error was evaluated by applying ±1mm/±3mm/±5mm to the X-axis, Y-axis, and Z-axis. Results: The dose-variation in skin due to Set-up error was approximately 106% to 123% compared to prescription dose, and the highest dose in skin was 49.24 Gy at 5mm Set-up error in the lateral direction of the X-axis. More than 107% of the prescription dose was the widest at 6.87 cc in skin lateral. Conclusions: If a Set-up error occurs during left breast cancer VMAT, a great difference in skin dose was shown in the lateral direction of the X-axis. If more effort is made to align the X-axis of the breast treated during CBCT registration, the dose-variation of skin will be reduced.

목 적: 방사선 피부염은 유방암 방사선 치료로 인해 발생하는 가장 흔한 부작용 중 하나로 본 연구는 자세오차에 따른 피부선량 차이를 분석하여 방사선 치료 부작용을 줄이고자 한다. 대상 및 방법 : 3D 프린터를 이용하여 유방 모형을 제작하고, 그것을 팬텀에 적용하였으며, 컴퓨터단층촬영을 통해 영상을 획득하였다. 처방선량의 95%가 들어가는 치료계획용적이 체적의 95%이상이 될 수 있도록, Dmax가 처방선량의 107%넘지 않게 치료계획하였다. 자세오차는 X축, Y축, Z축으로 ±1mm/±3mm/±5mm를 동일하게 적용하여 비교평가하였다. 결 과 : 자세오차 시 피부선량의 변동성은 처방선량 대비 약 106%에서 약 123%였으며 가장 큰 피부선량의 증가는 X축의 바깥쪽(lateral) 방향 5mm 자세오차에서 49.24 Gy였다. 처방선량 대비 107%이상의 영역은 skin lateral에서 6.87 cc로 가장 넓게 나타났다. 결 론 : 좌측 유방암 용적 변조 회전 방사선 치료 시 자세오차가 일어났을 경우 X축의 바깥쪽 방향에서 처방선량 대비 가장 큰 피부선량의 차이가 나타났다. 이를 통해 치료실 CBCT 정합 시 치료받는 쪽 유방의 Y축, Z축을 정합하는 것도 물론 중요하지만 X축을 정합하는데 더 노력한다면 치료 간 피부선량의 변동성을 더 줄이기 위한 효과적인 방법으로 사료된다.

Keywords

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