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通常低能医用加速器靶的设计遵从厚靶原则,即采用厚度等于或大于电子射程的靶,使靶后无电子污染.本文提出了新的靶设计概念:设计靶时,将靶与相关系统(初级准直锥、均整器)作为一个整体考虑,通过减小靶厚来提高光子剂量率,利用初级准直锥、均整器来减少电子污染.采用这种设计概念,用蒙特卡罗方法对BJ-6——6MV单光子医用电子直线加速器的靶进行优化设计.模拟计算10cm×10cm野,30cm×30cm野的深度剂量曲线,结果表明:较之现有的厚靶,治疗剂量提高了10%,同时表面剂量、X射线的品质仍满足国标的要求.通过薄靶、厚靶的加速器整机对比实验,已验证了此结论的正确性.
The design of low-energy medical accelerator targets is generally based on the principle of thick target, that is, the target with thickness equal to or greater than the electron range is used to make the target have no electronic pollution.This paper presents a new target design concept: Collimation cone, homogenizer) as a whole to consider, by reducing the target thickness to increase the photon dose rate, the use of primary collimation cone, averaging to reduce electronic pollution using this design concept, the Monte Carlo method BJ- 6 - 6MV single-photon medical electron linear accelerator to optimize the design of the dose of 10cm × 10cm field, 30cm × 30cm field depth dose curve, the results show that: compared to the existing thick target, the treatment dose increased by 10% At the same time, the surface dose and the quality of X-ray still meet the requirements of national standard.The correctness of this conclusion has been verified by comparing the whole machine with thin targets and thick targets.