Abstract：
Objective.In Intensity Modulated Proton Therapy (IMPT), the weights of individual pencil-beams or spots are optimized to fulfil dosimetric constraints. Theses spots are usually located on a regular lattice and their positions are fixed during optimization. In many cases, the range of spot weights may however be limited, leading sometimes to sub-optimal plan quality. An emblematic use case is the delivery of a plan at ultra-high dose rate (FLASH-RT), for which the spot weights are typically constrained to high values.Approach. To improve further the quality of IMPT FLASH plans, we propose here a novel algorithm to optimize both the spot weights and positions directly based on the objectives defined by the treatment planner.Main results. For all cases considered, optimizing the spot positions lead to an enhanced dosimetric score, while maintaining a high dose rate.Significance. Overall, this approach resulted in a substantial plan quality improvement compared to optimizing only the spot weights, and in a similar execution time.
摘要：
目标：在调强质子治疗（IMPT）中，各个笔形波束或点的权重被优化以满足剂量测定约束。这些斑点通常位于规则晶格上，并且在优化过程中它们的位置是固定的。在许多情况下,然而，斑点重量的范围可能是有限的，有时会导致计划质量次优。一个典型的用例是以超高剂量率（FLASH-RT）交付计划，点权重通常被约束到高值。
方法：为了进一步提高IMPTFLASH计划的质量，我们在这里提出了一种新颖的算法来优化斑点的权重和位置直接基于目标定义的治疗计划。
结果：对于所有考虑的情况，优化斑点位置导致增强的剂量测定分数，同时保持高剂量率。
结论：总体而言，与仅优化现货权重相比，这种方法导致了计划质量的实质性改进，和类似的执行时间。
方法：为了进一步提高IMPTFLASH计划的质量，我们在这里提出了一种新颖的算法来优化斑点的权重和位置直接基于目标定义的治疗计划。
结果：对于所有考虑的情况，优化斑点位置导致增强的剂量测定分数，同时保持高剂量率。
结论：总体而言，与仅优化现货权重相比，这种方法导致了计划质量的实质性改进，和类似的执行时间。
