目的:这项研究的目的是评估患者不同器官的FFB前列腺直线加速器放射治疗的继发性恶性肿瘤风险。
背景:放射治疗是癌症治疗的主要方法之一。然而,辐射的应用可能会对患者的器官施加剂量,这可能是某些恶性肿瘤的原因。
方法:蒙特卡罗(MC)模拟用于计算基于18MV线性加速器(直线加速器)的放射治疗中对患者器官的辐射剂量。使用人形MC体模计算不同器官的等效剂量和继发性癌症的可能性,致命和非致命风险,和其他风险和参数相关的大剂量放射治疗。在场外辐射计算中,可以看出,中子赋予远处器官更高的剂量,对周围器官的剂量主要是由于吸收的散射光子和电子污染。
结果:我们的结果表明,膀胱和皮肤分别为54.89×10-3mSv/Gy和46.09×10-3mSv/Gy,分别,从光中子吸收最高等效剂量,而较低剂量的肺吸收为3.42×10-3mSv/Gy。大肠和膀胱分别吸收55.00×10-3mSv/Gy和49.08×10-3,这是由于光子引起的最高等效剂量。大脑吸收了最低的野外剂量,1.87×10-3mSv/Gy。
结论:我们得出结论,次级中子部分高于其他辐射。然后,我们建议在基于直线加速器的高能放射治疗中,在辐射防护中更加注意中子。
OBJECTIVE: The aim of this
study was to estimate the secondary malignancy risk from the radiation in FFB prostate linac-based radiotherapy for different organs of the patient.
BACKGROUND: Radiation therapy is one of the main procedures of cancer treatment. However, the application the radiation may impose dose to organs of the patient which can be the cause of some malignancies.
METHODS: Monte Carlo (MC) simulation was used to calculate radiation doses to patient organs in 18 MV linear accelerator (linac) based radiotherapy. A humanoid MC phantom was used to calculate the equivalent dose s for different organs and probability of secondary cancer, fatal and nonfatal risk, and other risks and parameters related to megavoltage radiation therapy. In out-of-field radiation calculation, it could be seen that neutrons imparted a higher dose to distant organs, and the dose to surrounding organs was mainly due to absorbed scattered photons and electron contamination.
RESULTS: Our results showed that the bladder and skin with 54.89 × 10-3 mSv/Gy and 46.09 × 10-3 mSv/Gy, respectively, absorbed the highest equivalent dose s from photoneutrons, while a lower dose was absorbed by the lung at 3.42 × 10-3 mSv/Gy. The large intestine and bladder absorbed 55.00 × 10-3 mSv/Gy and 49.08 × 10-3, respectively, which were the highest equivalent dose s due to photons. The brain absorbed the lowest out-of-field dose, at 1.87 × 10-3 mSv/Gy.
CONCLUSIONS: We concluded that secondary neutron portion was higher than other radiation. Then, we recommended more attention to neutrons in the radiation protection in linac based high energy radiotherapy.