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Dosimetry verification of virtual wedge using a two-dimensional ionisation chamber array
Yu Lang, Yang Bo, Li Nan, Jiang Fei, Qiu Jie, Zhang Fuquan
Department of Radiation Oncology,Peking Union Medical College Hospital,Chinese Academy of Medical Sciences, Peking Union Medical College,100073 Beijing, China
Abstract Objective To investigate the virtual wedge (VW) dosimetric parameters with the ionization chamber array Matrixxenvlution. Methods Using Matrixxenvlution and solid water to measure and calculate Siemens accelerator′s VW angle and VW factors of different fields and compare the wedge field dose distribution to that of treatment planning system (TPS) by gamma analysis, summarized the measurement results of 50 times. Results The γ pass rate (3 mm/ 3%) of 15°and 30°VW in both direction were (91.47±1.76)%,(92.99±1.54)% and (93.27±1.24)%,(93.27±1.68)%, respectively, with the increase of filed size and the VW angle,but for 20 cm×20 cm field and VW 60°, the result was not very good. The largest angle deviation< 2°except small field size and wedge angle, VW factors were approximately equal to 1,the maximum deviation was no more than 0.05, plan dose distribution and themeasured dose distribution have good consistency except large field with large wedge angle. Conclusions Matrixxenvlution used in the measurement of VW dosimetric parameters which can obtain all parameters for angle calculation and dose plane analysis with only once positioning, and become more rapid, convenient, economical and practical one of quality assurance tools for VW dose verification.
Yu Lang,Yang Bo,Li Nan et al. Dosimetry verification of virtual wedge using a two-dimensional ionisation chamber array[J]. Chinese Journal of Radiation Oncology, 2015, 24(3): 340-342.
Yu Lang,Yang Bo,Li Nan et al. Dosimetry verification of virtual wedge using a two-dimensional ionisation chamber array[J]. Chinese Journal of Radiation Oncology, 2015, 24(3): 340-342.
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