VitalBeam 선형가속기의 심부선량백분율과 측방선량분포 측정을 위한 새로운 기준 전리함으로서 스텔스 전리함의 성능 평가

Performance Evaluation of Stealth Chamber as a Novel Reference Chamber for Measuring Percentage Depth Dose and Profile of VitalBeam Linear Accelerator

Abstract The purpose of this study is to evaluate the performance of a “stealth chamber” as a novel reference chamber for measuring percentage depth dose (PDD) and profile of 6, 8 and 10 MV photon energies. The PDD curves and dose profiles with fields ranging from 3 × 3 to 25 × 25 cm 2 were acquired from measurements by using the stealth chamber and CC 13 chamber as reference chamber. All measurements were performed with Varian VitalBeam linear accelerator. In order to assess the performance of stealth chamber, PDD curves and profiles measured with stealth chamber were compared with measurement data using CC13 chamber. For PPDs measured with both chambers, the dosimetric parameters such as d max (depth of maximum dose), D 50 (PDD at 50 ㎜ depth), and D 100 (PDD at 100 ㎜ depth) were analyzed. Moreover, root mean square error (RMSE) values for profiles at d max and 100 ㎜ depth were evaluated. The measured PDDs and profiles between the stealth chamber and CC13 chamber as reference detector had almost comparable. For PDDs, the evaluated dosimetric parameters were observed small difference (<1%) for all energies and field sizes, except for d max less than 2 ㎜. In addition, the difference of RMSEs for profiles at d max and 100 ㎜ depth was similar for both chambers. This study confirmed that the use of stealth chamber for measuring commission beam data is a feasible as reference chamber for fields ranging from 3 × 3 to 20 × 20 cm 2 . Furthermore, it has an advantage with respect to measurement of the small fields (less than 3 × 3 cm 2 field) although not performed in this study.