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针对逆向调强放疗中强度分布优化涉及的参数多,且临床上对其优化速度要求高的特点,将医生期望的靶区剂量和周围正常组织剂量限制转化为二次函数形式的目标函数,然后利用共轭梯度法对该目标函数进行优化。最后采用一例C形靶区紧密包围危及器官的模拟病例和一例临床常用的前列腺实例,在PC机(CPU E7200@2.53GHz,2.00GB内存,Windows XP)上对强度分布优化效果进行测试,对模拟病例10s便找到最优解;而对前列腺病例20s便可以找到最优解;且两个测试病例优化所得强度分布对应的剂量分布均满足要求。测试结果表明,采用共轭梯度法优化强度分布具有快速和效果好的优点,因此可以将其应用在精确放疗系统中。
According to the characteristics of intensity distribution optimization in reverse intensity modulated radiotherapy, and its clinical requirements for its high optimization speed, the target dose and the surrounding normal tissue dose limit expected by doctors are transformed into the objective function of quadratic function, and then The conjugate gradient method is used to optimize the objective function. Finally, a C-shaped target area was used to tightly enclose the endangering organ and a case of a commonly used prostate. The optimized intensity distribution was tested on a PC (CPU E7200 @ 2.53GHz, 2.00GB RAM, Windows XP) The optimal solution can be found in 10s and the optimal solution can be found in 20s of prostate cases. The dose distribution corresponding to the intensity distribution optimized by the two test cases meets the requirements. The test results show that the use of conjugate gradient method to optimize the intensity distribution has the advantages of fast and good effect, so it can be used in the precise radiotherapy system.