서울대병원 / 조진동, 박종민*, 김정인*
Abstract
Purpose: The aims of this study were to develop a flexible film dosimeter applicable to the irregular surface of a patient for in vivo dosimetry and to evaluate the device's dosimetric characteristics.
Methods: A flexible film dosimeter with active layers consisting of radiochromic-sensitive films and flexible silicone materials was constructed. The dose-response, sensitivity, scanning orientation dependence, energy dependence, and dose rate dependence of the flexible film dosimeter were tested. Irradiated dosimeters were scanned 24 h post-irradiation, and the region of interest was 5 mm × 5 mm. Biological stability tests ensured the safety of application of the flexible film dosimeter for patients. A preliminary clinical study with the flexible film dosimeter was implemented on four patients.
Results: The red channel demonstrated the highest sensitivity among all channels, and the response sensitivity of the dosimeter decreased with the applied dose, which were the same as the characteristics of GAFCHROMIC EBT3 radiochromic films. The flexible film dosimeter showed no significant energy dependence for photon beams of 6 MV, 6 MV flattening filter-free (FFF), 10 MV, and 15 MV. The flexible film dosimeter showed no substantial dose rate dependence with 6 or 6 MV FFF. In terms of biological stability, the flexible film dosimeter demonstrated no cytotoxicity, no irritation, and no skin sensitization. In the preliminary clinical study, the dose differences between the measurements with the flexible film dosimeter and calculations with the treatment planning system ranged from -0.1% to 1.2% for all patients.
Conclusions: The dosimeter developed in this study is a flexible film capable of attachment to a curved skin surface. The biological test results indicate the stability of the flexible film dosimeter. The preliminary clinical study showed that the flexible film dosimeter can be successfully applied as an in vivo dosimeter.
그림 . (a) 개발한 dosimeter의 구성 및 (b) 실험에 사용한 dosimeter의 크기, (c) 개발한 dosimeter를 적용한 예 및 (d) dosimeter의 단면도
Affiliations
Jin Dong Cho 1 2 3 , Jaeman Son 1 4 , Jiwon Sung 1 4 , Chang Heon Choi 1 2 4 , Jin Sung Kim 3 , Hong-Gyun Wu 1 2 4 5 6 , Jong Min Park 1 2 4 7 , Jung-In Kim 1 2 4
1 Department of Radiation Oncology, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
2 Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, 03080, Republic of Korea.
3 Department of Radiation Oncology, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea.
4 Biomedical Research Institute, Seoul National University Hospital, Seoul, 03080, Republic of Korea.
5 Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
6 Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea.
7 Robotics Research Laboratory for Extreme Environments, Advanced Institute of Convergence Technology, Suwon, 16229, Republic of Korea.
편집위원
기존 EBT필름을 대체하여 Rectal wall이나 Lens등에 사용가능한 In-vivo 연구 이므로 관심이 갑니다
2020-08-26 15:38:42
편집위원2
본 논문은 유연한 실리콘 고무 재질인 LIPCDA로 코팅한 활성층이 있는 유연한 방사크로믹 필름 선량계를 제작하여 생체 내 선량측정계((In vivo dosimeter)로써의 물리적인 정확성 및 임상 유용성 여부를 검증하기 위해 선량학적인 특성을 조사 및 평가하는데 있다. 본 연구에서 개발된 유연한 필름 선량계는 다양한 선량학적인 특성이 우수하고, 생물학적인 안정성이 검증되었다. 특히 환자 피부면의 불규칙한 요철이나 곡선인 방사선치료 부위(관심 영역 5 mm x 5 mm) 등에 대한 예비 임상 적용 4건의 사례에서 치료계획시스템을 사용한 선량 계산값과 차이에서 모든 환자에 대해 -0.1% 내지 1.2%의 범위 내에서 일치하였다. 그러므로 본 연구에서 개발된 유연한 필름 선량계는 VMAT나 SBRT, SRS 등 환자맞춤형 고정밀 방사선치료/수술 중 생체 내 2D 선량측정에 매우 유익할 것으로 기대된다.
2020-08-26 15:39:04