방사선의학 웹진

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Abstract
FLASH radiation therapy reduced radiation-induced damage to normal tissue, compared to conventional radiation therapy, and active studies have been undertaken worldwide. While a number of preclinical studies have revealed the effectiveness of this novel radiotherapy, the biological effects have not been fully elucidated. Here, we implemented ultra-high dose-rate FLASH beam irradiation through machine modifications of the core components of an existing clinical linear accelerator, to build a database containing information related to the biological effects of the FLASH beam. We established a protocol that enables a quick conversion between the CONV and FLASH modes of an existing clinical linear accelerator. At 100 cm source-to-surface distance in 10 cm × 10 cm applicator conditions, we achieved FLASH electron beam irradiation characterized by 9.49 MeV mean energy, effective field size (95% iso-dose distribution) ∅ 39.9 mm, and maximum dose rate of 339.1 Gy/s. Irradiation of an elliptical Gaussian beam with flatness of 12.7% and symmetry of 0.3% was confirmed. Furthermore, most of the required preclinical conditions were satisfied. However, although the pulse dose value obtained from the protocol is expected to meet the requirement of 1 Gy/pulse, this result was not confirmed in this study, and further investigation is required.

Affiliations

Gyu-Seok Cho 1, Kyo-Tae Kim 1 2, Soon-Sung Lee 1, Jeong-Hwan Kim 1, Dong-Han Lee 3, Hong-Suk Chang 1, Sang-Hyoun Choi 1, Kum-Bae Kim 1, Tae-Keun Yang 1, Dong-Hyun An 1, Geun-Beom Kim 1, Kun-Uk Kang 1, Jin-Kyu Kang 4, Eun-Ji Kim 4 5, Eun-Kyung Paik 4, Mi-Sook Kim 4, Won-Il Jang 4, Kwang-Mo Yang 4
1Radiation Therapy Technology and Standards, Korea Institute of Radiological and Medical Sciences, Seoul, Korea.
2Department of Research and Development, GEMSS Healthcare Co., Ltd, Goyang, Korea.
3Department of Cyberknife, Korea Institute of Radiological & Medical Sciences, Seoul, Korea.
4Department of Radiation Oncology, Korea Institute of Radiological & Medical Sciences, Seoul, Korea.
5Department of Radiation Oncology, Seoul Metropolitan Government - Seoul National University Boramae Medical Center, Seoul, Korea.