Optimization of current modulation function for proton spread-out Bragg peak fields.
Optimization of current modulation function for proton spread-out Bragg peak fields.
复制标题
质子扩散布拉格峰场的电流调制函数的优化。
DOI：
10.1118/1.2188072
复制
发表时间：
2006
期刊：
影响因子：
3.8
通讯作者：
Kooy,Hanne
中科院分区：
文献类型：
--
作者：
Lu,Hsiao-Ming;Kooy,Hanne
使用扩展布拉格峰（SOBP）场的质子治疗通常使用不同厚度的旋转调制轮来调制原始布拉格峰的深度和强度。在轮旋转过程中独立调制射束电流的技术提供了对拉回布拉格峰强度的额外控制。因此，单个轮可以在大范围的能量和SOBP参数中使用，并且不再需要特定于场的轮。调试特定治疗深度的基本任务是确定该电流调制函数。我们已经开发了一种方法的电流调制函数的优化。基本思想是将容纳各种射束散射和调制组件的整个射束喷嘴作为一个整体来处理，并将其效果表征为从调制射束电流到深度剂量分布的转换。虽然由于喷嘴和体模中的复杂散射路径，这种转换很难在理论上计算，但可以通过时间分辨剂量测量来确定。使用这种变换，我们可以计算任何电流调制函数的SOBP深度剂量分布，并通过简单的数值优化来优化它。我们已将新方法应用于若干质子束流，得到了满意的结果。
Proton treatments with spread‐out Bragg peak (SOBP) fields often use a rotating modulation wheel of varying thickness to modulate the pristine Bragg peak in depth and intensity. The technique of modulating also the beam current independently over the wheel rotation provides an additional control over the intensities of the pulled‐back Bragg peaks. As a result, a single wheel can be used over a large range of energies and SOBP parameters and field‐specific wheels are no longer necessary. An essential task in commissioning a particular treatment depth is the determination of this current modulation function. We have developed a method for the optimization of the current modulation function. The basic idea is to treat the entire beam nozzle, housing the various beam scattering and modulating components, as a whole and to characterize its effect as a transformation from a modulating beam current to a depth‐dose distribution. While this transformation is difficult to calculate theoretically due to the complex scattering paths in the nozzle and the phantom, it can, however, be determined by time‐resolved dose measurements. Using this transformation, we can calculate SOBP depth‐dose distributions for any current modulation function and optimize it by a simple numerical optimization. We have applied the new method to a number of proton beams with satisfactory results.