Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
Department of Radiation Oncology, Erasmus MC Cancer Institute, Rotterdam, the Netherlands.
Radiother Oncol. 2024 Jan;190:110009. doi: 10.1016/j.radonc.2023.110009. Epub 2023 Nov 14.
Since 2011, our center has been using a library-based Plan-of-the-Day (PotD) strategy for external beam radiotherapy of cervical cancer patients to reduce normal tissue dose while maintaining adequate target coverage. With the advent of fully online-adaptive techniques such as daily online-adaptive replanning, further dose reduction may be possible. However, it is unknown how this reduction relates to plan library approaches, and how the most recent PotD strategies relate to no adaptation. In this study we compare the performance of our current PotD strategy with non-adaptive and fully online-adaptive techniques in terms of target volume size and normal tissue sparing.
Treatment data of 376 patients treated with the PotD protocol between June 2011 and April 2020 were included. The size of the Planning Target Volumes (PTVs) was reconstructed for different strategies: full online adaptation, no adaptation, and the latest clinical version of the PotD protocol. Normal tissue sparing was estimated by the difference in margin volume to construct the PTV and the volume overlap of the PTV with bladder and rectum.
The current version of our PotD approach reduced the PTV margin volume by a median of 250 cm compared to no adaptation. Bladder-PTV overlap decreased from a median of 142 to 71 cm, and from 39 to 16 cm for rectum-PTV. Fully online-adaptive approaches could further decrease the PTV volume by 144 cm using a 5 mm margin for residual errors. In this scenario, bladder-PTV overlap was reduced to 35 cm and rectum-PTV overlap to 11 cm.
The current version of the PotD protocol is an effective technique to improve normal tissue sparing compared to no adaptation. Further sparing can be achieved using fully online-adaptive techniques, but at the cost of a more complex workflow and with a potentially limited impact. PotD-type protocols can therefore be considered as a suitable alternative to fully online-adaptive approaches.
自 2011 年以来，我们中心一直使用基于计划的每日计划（Plan-of-the-Day，PotD）策略为宫颈癌患者进行外照射放疗，以降低正常组织剂量，同时保持足够的靶区覆盖。随着全在线自适应技术（如每日在线自适应再计划）的出现，可能进一步降低剂量。然而，目前尚不清楚这种减少与计划库方法的关系，以及最新的 PotD 策略与无适应的关系。在这项研究中，我们比较了我们目前的 PotD 策略与非自适应和全在线自适应技术在靶区体积大小和正常组织保护方面的性能。
纳入了 2011 年 6 月至 2020 年 4 月期间采用 PotD 方案治疗的 376 例患者的治疗数据。不同策略下重建了计划靶区（PTV）的大小：全在线自适应、无自适应和最新临床版本的 PotD 方案。通过构建 PTV 的边界体积与膀胱和直肠 PTV 重叠的差异来估计正常组织的保护情况。
与无自适应相比，当前版本的 PotD 方法将 PTV 边界体积减少了中位数 250cm。膀胱-PTV 重叠从中位数 142cm 减少到 71cm，从 39cm 减少到 16cm。使用 5mm 残留误差边界，全在线自适应方法可进一步减少 PTV 体积 144cm。在此情况下，膀胱-PTV 重叠减少至 35cm，直肠-PTV 重叠减少至 11cm。
与无自适应相比，当前版本的 PotD 方案是一种提高正常组织保护的有效技术。使用全在线自适应技术可以进一步减少正常组织的保护，但需要更复杂的工作流程，且潜在影响有限。因此，PotD 型方案可作为全在线自适应方法的替代方案。
