Masoumi Hossein, Mokhtari-Dizaji Manijhe, Arbabi Azim, Bakhshandeh Mohsen
Medical Physics Department, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
Radiotherapy and Oncology Department, Faculty of Medical Sciences, Shahid Beheshti University of Medical Sciences and Health Services, Tehran, Iran.
Dose Response. 2016 Feb 11;14(1):1559325815625647. doi: 10.1177/1559325815625647. eCollection 2016 Jan-Mar.
In this study, using methacrylic and ascorbic acid in gelatin initiated by copper (MAGIC-f) polymer gel after megavoltage energy exposure, the sensitivity of the ultrasound velocity and attenuation coefficient dose-dependent parameters was evaluated. The MAGIC-f polymer gel was irradiated under 1.25 MeV cobalt-60, ranging from 0 to 60 Gy in 2-Gy steps, and received dose uniformity and accuracy of ±2%. After calibration of the ultrasonic systems with a frequency of 500 kHz, the parameters of ultrasound velocity and attenuation coefficient of the irradiated gel samples were measured. According to the dose-response curve, the ability of ultrasonic parameters was evaluated in dose rate readings. Based on a 4-order polynomial curve, fitted on the dose-response parameters of ultrasound velocity and attenuation coefficient and observed at 24 hours after irradiation, ultrasonic parameters had more sensitivity. The sensitivity of the dose-velocity and dose-attenuation coefficient curves was observed as 50 m/s/Gy and 0.06 dB/MHz/Gy over the linear range of 4 to 44 Gy, respectively. The ultrasonic parameters at 5°C, 15°C, and 25°C on the gel dosimeter after 0 to 60 Gy irradiation showed that readings at 25°C have higher sensitivity compared to 15°C and 5°C. Maximum sensitivity time and temperature readings of the MAGIC-f ultrasonic parameters were concluded 24 hours after irradiation and at a temperature of 25°C.
在本研究中，使用由铜引发的明胶中的甲基丙烯酸和抗坏血酸（MAGIC-f）聚合物凝胶在兆伏能量照射后，评估了超声速度和衰减系数剂量依赖性参数的敏感性。MAGIC-f聚合物凝胶在1.25 MeV钴-60下照射，剂量范围为0至60 Gy，步长为2 Gy，剂量均匀性和准确性为±2%。在用500 kHz频率校准超声系统后，测量了照射后凝胶样品的超声速度和衰减系数参数。根据剂量响应曲线，在剂量率读数中评估超声参数的能力。基于拟合在超声速度和衰减系数剂量响应参数上的四阶多项式曲线，并在照射后24小时观察到，超声参数具有更高的敏感性。在4至44 Gy的线性范围内，剂量-速度和剂量-衰减系数曲线的敏感性分别为50 m/s/Gy和0.06 dB/MHz/Gy。在0至60 Gy照射后，凝胶剂量计在5°C、15°C和25°C下的超声参数显示，25°C下的读数比15°C和5°C下具有更高的敏感性。得出MAGIC-f超声参数的最大敏感性时间和温度读数为照射后24小时和温度为25°C。
