Ataei Gholamreza, Rezaei Maral, Gorji Kourosh Ebrahimnejad, Banaei Amin, Goushbolagh Nouraddin Abdi, Farhood Bagher, Bagheri Mahmoud, Firouzjah Razzagh Abedi
Department of Radiology Technology, Faculty of Paramedical Sciences, Babol University of Medical Sciences, Babol, Iran.
Department of Medical Radiation, Science and Research Branch, Islamic Azad University, Tehran, Iran.
J Med Signals Sens. 2019 Aug 29;9(3):204-210. doi: 10.4103/jmss.JMSS_45_18. eCollection 2019 Jul-Sep.
Gafchromic films are utilized for two-dimensional dose distribution measurements, especially in radiotherapy. In this study, we investigated a close connection between energy and dose rate of Gafchromic EBT3 films irradiating with 6 MV and Co-60 photon beams over a broad dose range. EBT3 films were exposed to 6 MV and Co-60 photon beams using 4 and 2 Gy/min dose rates over a 10-400 cGy dose range. The films were scanned in red, green, and blue channels to obtain the optical density (OD)-dose curves. The OD-dose curves resulted from three-color scans for different photon energies and dose rates were compared by statistical independent -test. For the radiations of Co-60 and 6 MV photon beams, the highest correlation was obtained between the 2 and 4 Gy/min dose rates with red and green channels, respectively. Moreover, the red channel had a greater OD response per dose value, following the green and blue channels. There was no significant difference between different photon energies' (Co-60 and 6 MV) and dose rates' (2 and 4 Gy/min) dependence on OD-dose response of EBT3 films over a broad domain of radiation dose, except for different photon energies in the blue channel. Our results revealed that the OD-dose response of EBT3 films is independent on photon energies (Co-60 and 6 MV) and dose rate (2 and 4 Gy/min) in the evaluated dose range (10-400 cGy). Therefore, the EBT3 films are suitable, consistent, and reliable instruments for dose measurements in radiotherapy.
辐射变色薄膜用于二维剂量分布测量，尤其是在放射治疗中。在本研究中，我们研究了在宽剂量范围内用6兆伏和钴 - 60光子束照射时，辐射变色EBT3薄膜的能量与剂量率之间的紧密联系。EBT3薄膜在10 - 400厘戈瑞剂量范围内，分别以4和2戈瑞/分钟的剂量率接受6兆伏和钴 - 60光子束照射。对薄膜进行红、绿、蓝通道扫描以获得光密度（OD）-剂量曲线。通过统计独立t检验比较不同光子能量和剂量率的三色扫描得到的OD - 剂量曲线。对于钴 - 60和6兆伏光子束的辐射，分别在2和4戈瑞/分钟剂量率下，红通道和绿通道获得了最高的相关性。此外，红通道每剂量值的OD响应更大，其次是绿通道和蓝通道。除了蓝通道中不同光子能量外，在宽辐射剂量范围内，不同光子能量（钴 - 60和6兆伏）和剂量率（2和4戈瑞/分钟）对EBT3薄膜OD - 剂量响应的依赖性没有显著差异。我们的结果表明，在评估的剂量范围（10 - 400厘戈瑞）内，EBT3薄膜的OD - 剂量响应与光子能量（钴 - 60和6兆伏）和剂量率（2和4戈瑞/分钟）无关。因此，EBT3薄膜是放射治疗中剂量测量的合适、一致且可靠的仪器。
