Proton Therapy Center, National Cancer Center, Goyang, Korea.
Department of Bioconvergence Engineering, Korea University, Seoul, Korea.
Med Phys. 2022 Jul;49(7):4768-4779. doi: 10.1002/mp.15664. Epub 2022 Apr 18.
To evaluate the dosimetric characteristics and applications of a dosimetry system composed of a flexible amorphous silicon thin-film solar cell and scintillator screen (STFSC-SS) for therapeutic X-rays.
The real-time dosimetry system was composed of a flexible a-Si thin-film solar cell (0.2-mm thick), a scintillator screen to increase its efficiency, and an electrometer to measure the generated charge. The dosimetric characteristics of the developed system were evaluated including its energy dependence, dose linearity, and angular dependence. Calibration factors for the signal measured by the system and absorbed dose-to-water were obtained by setting reference conditions. The application and correction accuracy of the developed system were evaluated by comparing the absorbed dose-to-water measured using a patient treatment beam with that measured using the ion chamber.
The responses of STFSC-SS to energy, field size, depth, and source-to-surface distance (SSD) were more dependent on measurement conditions than were the responses of the ion chamber, although the former dependence was due to the scintillator screen, not the solar cell. The signals of STFSC-SS were also dependent on dose rate, while the responses of solar cell alone and scintillator screen were not dependent on dose rate. The scintillator screen reduced the output of solar cell at 6 and 15 MV by 0.60 and 0.55%, respectively. The different absorbed dose-to-water measured using STFSC-SS for patient treatment beam differed by 0.4% compared to those measured using the ionization chamber. The uncertainties of the developed system for 6 and 15 MV photon beams were 1.8 and 1.7%, respectively, confirming the accuracy and applicability of this system.
The thin-film solar cell-based detector developed in this study can accurately measure absorbed dose-to-water. The increased signal resulting from the use of the scintillator screen is advantageous for measuring low doses and stable signal output. In addition, this system is flexible, making it applicable to curved surfaces, such as a patient's body, and is cost-effective.
评估由柔性非晶硅薄膜太阳能电池和闪烁体屏（STFSC-SS）组成的治疗 X 射线剂量学系统的剂量学特性和应用。
实时剂量学系统由柔性 a-Si 薄膜太阳能电池（0.2 毫米厚）、一个闪烁体屏以提高其效率和静电计来测量产生的电荷组成。开发系统的剂量学特性进行了评估，包括能量依赖性、剂量线性度和角度依赖性。通过设定参考条件，获得了系统测量信号的校准因子和水吸收剂量。通过比较患者治疗束测量的水吸收剂量和使用电离室测量的水吸收剂量，评估了开发系统的应用和校正精度。
与电离室相比，STFSC-SS 对能量、射野大小、深度和源皮距（SSD）的响应更依赖于测量条件，尽管前者的依赖性是由于闪烁体屏，而不是太阳能电池。STFSC-SS 的信号也依赖于剂量率，而单独的太阳能电池和闪烁体屏的响应不受剂量率的影响。闪烁体屏使 6MV 和 15MV 时太阳能电池的输出分别降低了 0.60%和 0.55%。使用 STFSC-SS 测量患者治疗束的水吸收剂量与使用电离室测量的水吸收剂量相差 0.4%。对于 6MV 和 15MV 光子束，开发系统的不确定度分别为 1.8%和 1.7%，证实了该系统的准确性和适用性。
本研究中开发的基于薄膜太阳能电池的探测器可以准确测量水吸收剂量。使用闪烁体屏产生的增加的信号有利于测量低剂量和稳定的信号输出。此外，该系统具有灵活性，适用于曲面，如患者的身体，并且具有成本效益。
