Parwaie Wrya, Geraily Ghazale, Mehri-Kakavand Ghazal, Babaloui Somayyeh, Rezvani Samira, Pursamimi Mohamad
Department of Medical Physics, Faculty of Paramedical Sciences, Ilam University of Medical Sciences, Ilam, Iran.
Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Rep Pract Oncol Radiother. 2022 May 19;27(2):226-234. doi: 10.5603/RPOR.a2022.0031. eCollection 2022.
The presence of heterogeneity within the radiation field increases the challenges of small field dosimetry. In this study, the performance of MAGIC polymer gel was evaluated in the dosimetry of small fields beyond bone heterogeneity.
Circular field sizes of 5, 10, 20 and 30 mm were used and Polytetrafluoroethylene with density of 2.2 g/cm was used as the bone equivalent material. The PDD curves, beam profiles, and penumbra widths were measured using MAGIC polymer gel, EBT2 film, and Monte Carlo simulation.
The maximum differences between MAGIC and EBT2 are 6.1, 4.7, 2.4, and 2.2 for PDD curves at 5, 10, 20, and 30 mm circular fields, respectively. The dose differences and distance to agreement between MAGIC and MC were within 1.89%/0.46 mm, 1.66%/0.43 mm, 1.28%/0.77 mm, and 1.31%/0.81 mm for beam profile values behind bone heterogeneity at 5, 10, 20, and 30 mm field sizes, respectively.
The results presented that the MAGIC polymer gel dosimeter is a proper instrument for dosimetry beyond high density heterogeneity.
辐射野内的异质性增加了小射野剂量学的挑战。在本研究中，评估了MAGIC聚合物凝胶在骨异质性之外的小射野剂量学中的性能。
使用直径为5、10、20和30 mm的圆形射野，以密度为2.2 g/cm的聚四氟乙烯作为骨等效材料。使用MAGIC聚合物凝胶、EBT2胶片和蒙特卡罗模拟测量百分深度剂量（PDD）曲线、射野轮廓和半值层宽度。
对于直径为5、10、20和30 mm的圆形射野，MAGIC与EBT2在PDD曲线上的最大差异分别为6.1、4.7、2.4和2.2。对于5、10、20和30 mm射野尺寸下骨异质性后方的射野轮廓值，MAGIC与蒙特卡罗模拟之间的剂量差异和达成一致的距离分别在1.89%/0.46 mm、1.66%/0.43 mm、1.28%/0.77 mm和1.31%/0.81 mm以内。
结果表明，MAGIC聚合物凝胶剂量仪是一种适用于高密度异质性之外剂量学的仪器。
