The high conformality of intensity-modulated proton therapy (IMPT) dose distributions causes treatment plans to be sensitive to geometrical changes during the course of a fractionated treatment. This can be addressed using adaptive proton therapy (APT). One important question in APT is the frequency of adaptations performed during a fractionated treatment, which is related to the question whether plan adaptation has to be done online or offline. The purpose of this work is to investigate the impact of weekly and daily online IMPT plan adaptation on the treatment quality for head and neck patients. A cohort of ten head and neck patients with daily acquired cone-beam CT (CBCT) images was evaluated retrospectively. Dose tracking of the IMPT treatment was performed for three scenarios: base plan with no adaptation (BP), weekly online adaptation (OA_W), and daily online adaptation (OA_D). Both adaptation schemes used an in-house developed online APT workflow, performing Monte Carlo dose calculations on scatter-corrected CBCTs. IMPT plan adaptation was achieved by only tuning the weights of a subset of beamlets, based on deformable image registration from the planning CT to each CBCT. Although OA_D mitigated random delivery errors more effectively than OA_W on a fraction per fraction basis, both OA_W and OA_D achieved the clinical goals for all ten patients, while BP failed for six cases. In the high-risk CTV, accumulated values of D _98% ranged between 97.15% and 99.73% of the prescription dose for OA_D, with a median of 98.07%. For OA_W, values between 95.02% and 99.26% were obtained, with a median of 97.61% of the prescription dose. Otherwise, the dose to most organs at risk was similar for all three scenarios. Globally, our results suggest that OA_W could be used as an alternative approach to OA_D for most patients in order to reduce the clinical workload.

调强质子治疗 (IMPT) 剂量分布的高度适形性导致治疗计划对分次治疗过程中的几何变化敏感。这可以使用适应性质子疗法 (APT) 来解决。APT 中的一个重要问题是分次治疗期间进行调整的频率，这与计划调整是否必须在线或离线进行的问题有关。这项工作的目的是调查每周和每日在线 IMPT 计划调整对头颈部患者治疗质量的影响。回顾性评估了一组 10 名头颈部患者每日获得的锥形束 CT (CBCT) 图像。IMPT 治疗的剂量跟踪针对三种情况进行：无适应的基本计划 (BP)、每周在线适应 (OA)_W）和每日在线改编（OA _D）。两种适应方案都使用内部开发的在线 APT 工作流程，对散射校正的 CBCT 执行蒙特卡罗剂量计算。基于从计划 CT 到每个 CBCT 的可变形图像配准，仅通过调整子束子集的权重来实现 IMPT 计划调整。尽管 OA _{D比 OA W}更有效地减轻了随机递送错误，但 OA _W和 OA _D均达到了所有 10 名患者的临床目标，而 BP 则有 6 例患者失败。在高危 CTV 中，D _98%的累积值介于 OA 处方剂量的 97.15% 和 99.73% 之间_D，中位数为 98.07%。OA _W的值在 95.02% 和 99.26% 之间，中位数为处方剂量的 97.61%。否则，在所有三种情况下，大多数处于危险中的器官的剂量都是相似的。在全球范围内，我们的结果表明，OA _W可用作大多数患者的 OA _D替代方法，以减少临床工作量。