Brahme A
Department of Radiation Physics, Karolinska Institute, Stockholm, Sweden.
Radiother Oncol. 1988 Jun;12(2):129-40. doi: 10.1016/0167-8140(88)90167-3.
A new approach is suggested for the optimization of stationary and more general moving beam type of irradiations. The method reverses the order of conventional treatment planning as it derives the optimum incident beam dose distributions from the desired dose distribution in the target volume. It is therefore deterministic and largely avoids the trial and error approach often applied in treatment planning of today. Based on the approximate spatial invariance of the convergent beam point irradiation dose distribution, the desired dose distribution in the target volume is analyzed in terms of the optimum density of such point irradiations. Since each point irradiation distribution is optimal for the irradiation of a given point and due to the linearity of individual energy depositions or absorbed dose contributions, the resultant point irradiation density will also generate the best possible irradiation of an extended target volume when the maximum absorbed dose at a certain distance from the target should be minimized. The optimum shape of the incident beam for each position of the gantry is obtained simply by inverse back projection of the point irradiation density on the position of the radiation source for that orientation of the incident beam.
本文提出了一种新方法，用于优化固定及更一般的移动束类型的辐照。该方法颠倒了传统治疗计划的顺序，因为它从靶区所需的剂量分布中推导出最佳的入射束剂量分布。因此，它是确定性的，并且很大程度上避免了当今治疗计划中经常采用的试错法。基于会聚束点照射剂量分布的近似空间不变性，根据这种点照射的最佳密度来分析靶区所需的剂量分布。由于每个点照射分布对于给定一点的照射都是最优的，并且由于单个能量沉积或吸收剂量贡献的线性特性，当距靶区一定距离处的最大吸收剂量应减至最小时，所得的点照射密度也将对扩展的靶区产生尽可能最佳的照射。通过将点照射密度反向投影到该入射束方向的辐射源位置上，即可简单地获得每个机架位置处入射束的最佳形状。
