Comparative Analysis of Film Dosimeter and Diode Detector in Small Field Dosimetry
GAO Xiang1,YU Yan-juan2,SHI Li-wan1
1. Department of Radiation Oncology, First Affiliated Hospital of Xiamen University,
Xiamen, Fujian 361001, China
2. College of Electronic Engineering, Zhangzhou Institute of Technology, Zhangzhou, Fujian 363000, China
摘要小照射野的建模数据对于调强放射治疗和立体放射治疗十分重要。在加速器使用6MV光子束条件下,采用胶片与0.01cm3的半导体探头,在IBA Blue Phantom 2水箱与固体水中,测量0.6cm×0.6cm至10.0cm×10.0cm照射野的百分深度剂量(PDD)曲线、profile、点剂量等数据,并计算射野总散射因子Scp。测试结果表明:对于PDD曲线,不同的照射野情况下,半导体探头与胶片在建成区测得数据基本吻合,在水深2～10cm测量结果存在微小偏差,当水深超过10cm以后差距明显(达7%);对于profile曲线,不同照射野下,胶片与半导体探头测量数据无明显差异,但胶片具有更好的空间分辨率,体现在半影区剂量跌落更明显;半导体探头、胶片剂量仪测得的点剂量与计划系统计算相同深度的点剂量比较,差异明显(最大误差分别为-2.7%、12%)。分析得出:不同的测量探头,对小野物理数据测量的准确性可能存在很大差异;胶片剂量仪具有优越的空间分辨率,但是胶片的吸收剂量范围有限,具有能量和方向依赖性。
Abstract：For precise radiotherapy, especially stereotactic radiotherapy and intensity-modulated radiotherapy, the small irradiation field modeling data is particularly important. The tissue maximum dose ratio, the profile, point dose and total scattering factor Scp were measured and calculated under the condition of the accelerator with 6MV photons, using the film and diode detector, with 0.01cm3 in IBA Blue Phantom 2 tank and solid water, measuring the irradiation field of 0.6cm×0.6cm～10.0cm×10.0cm. The results showed: For percentage depth dose (PDD) curves, the measured data of digital diode detector and film in built-up area were basically consistent in different exposure fields, and there was a small deviation in the measurement results in water depth of 2～10cm, with a significant difference after water depth of 10cm (almost 0.07). For the profile curve, there was no significant difference between the measured data of film and finger diode detector under different irradiation fields. Conclusions were drawn as follows: (1)For different measuring probe, the accuracy of the physical measurements may differ greatly.(2)Film dosimeter has superior spatial resolution, but film absorbed dose range is limited, energy and directional are dependenced.
高翔,余燕娟,石丽婉. 胶片剂量仪与半导体探测器在小野剂量数据测量中的比较分析[J]. 计量学报, 2020, 41(7): 873-878.
GAO Xiang,YU Yan-juan,SHI Li-wan. Comparative Analysis of Film Dosimeter and Diode Detector in Small Field Dosimetry. Acta Metrologica Sinica, 2020, 41(7): 873-878.
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2020, Vol. 41 
