Measurement and application of radiation field distribution in Halcyon linear accelerator treatment room
10.13491/j.issn.1004-714X.2025.05.018
- VernacularTitle:Halcyon直线加速器机房内辐射剂量场分布测量与应用
- Author:
Yatao LIU
1
;
Yanling YI
2
;
Wentao ZHAO
2
;
Haikuan LIU
2
;
Xiangyu E
1
;
Jingping YU
1
;
Hongwei ZENG
1
Author Information
1. Shuguang Hospital Affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
2. Institute of Radiation Medicine, Fudan University, Shanghai 200032, China.
- Publication Type:OriginalArticles
- Keywords:
Halcyon linear accelerator;
Radiation field;
Thermoluminescence dosimeter;
Shielding design
- From:
Chinese Journal of Radiological Health
2025;34(5):740-745
- CountryChina
- Language:Chinese
-
Abstract:
Objective To measure radiation filed distribution in the treatment room of the Varian Halcyon medical linear accelerator, and to provide a basis for shielding design and potential exposure analysis of treatment rooms for this type of accelerator. Methods Under the 6 MV X-ray (FFF) mode at a maximum dose rate of 800 MU/min and a maximum irradiation field of 28.00 cm × 28.00 cm, a total of 540 MU was delivered during gantry rotation. Radiation field distribution was measured using thermoluminescence dosimeters located at multiple points in the room. The measured data were then applied to shielding calculations, and the results were compared with those obtained using empirical formulas. Results The overall radiation levels in the treatment room were in the range of 12.2 µGy/540 MU to 5.520 Gy/540 MU, with the highest dose (5.520 Gy/540 MU) observed at the isocenter, and the lowest dose (12.2 µGy/540 MU) recorded at approximately 6.5 m from the gantry head. The radiation levels at most points were within the range of 100-1000 µGy/540 MU. At heights of 0.5, 1.1, and 1.7 m, the radiation field exhibited a rapid attenuation from the beam center outward, with a faster decay along the treatment couch direction (Y-axis) than along the perpendicular direction (X-axis). Shielding calculations based on the measured radiation field yielded required wall thicknesses of 1219 mm (east wall), 949 mm (south wall), 1235 mm (west wall), and 1252 mm (north wall), all of which were smaller than those calculated using empirical formulas. Conclusion Thermoluminescence dosimeter is suitable for multi-point in situ measurement of radiation field distribution in Halcyon accelerator treatment rooms. The measurement results can be used to optimize the shielding design of Halcyon accelerator treatment rooms.
