Mason Sarah A, Wang Lei, Alexander Sophie E, Lalondrelle Susan, McNair Helen, Harris Emma J
The Institute of Cancer Research, London, United Kingdom.
The Royal Marsden NHS Trust, London, United Kingdom.
Phys Med Biol. 2025 Jun 23;70(12):125020. doi: 10.1088/1361-6560/ade197.
To facilitate implementation of plan-of-the-day (POTD) selection for treating locally advanced cervical cancer (LACC), we developed a POTD assessment tool for CBCT-guided radiotherapy (RT). A female pelvis segmentation model (U-Seg3) is combined with a novel quantitative standard operating procedure (qSOP) to identify optimal and acceptable plans.The planning CT[i], corresponding structure set[ii], and manually contoured CBCTs[iii] (= 226) from 39 LACC patients treated with POTD (= 11) or non-adaptive RT (= 28) were used to develop U-Seg3, an algorithm incorporating deep-learning and deformable image registration techniques to segment the low-risk clinical target volume (LR-CTV), high-risk CTV (HR-CTV), bladder, rectum, and bowel bag. A single-channel input model (iii only, U-Seg1) was also developed. Contoured CBCTs from the POTD patients were (a) reserved for U-Seg3 validation/testing, (b) audited to determine optimal and acceptable plans, and (c) used to empirically derive a qSOP that maximised classification accuracy.The median (interquartile range) dice similarity coefficient (DSC) between manual and U-Seg3 contours was 0.83 [0.80], 0.78 [0.13], 0.94 [0.05], 0.86 [0.09], and 0.90 [0.05] for the LR-CTV, HR-CTV, bladder, rectum, and bowel. These were significantly higher than U-Seg1 in all structures but bladder. The qSOP classified plans as acceptable if they met target coverage thresholds (LR-CTV⩾99%, HR-CTV⩾99.8%), with lower LR-CTV coverage (⩾95%) sometimes allowed. The acceptable plan minimizing bowel irradiation was considered optimal unless substantial bladder sparing could be achieved. With U-Seg3 embedded in the qSOP, optimal and acceptable plans were identified in 46/60 and 57/60 cases.U-Seg3 outperforms U-Seg1 and all known CBCT-based segmentation models of the female pelvis both in terms of scope and accuracy (median DSC improvement ranging from 0.03-0.06). The tool combining U-Seg3 and the qSOP identifies optimal plans with equivalent accuracy as two observers. In an implementation strategy whereby this tool serves as the second observer, plan selection confidence and decision-making time could be improved whilst simultaneously reducing the required number of POTD-trained radiographers by 50%.
为了便于实施每日计划（POTD）选择以治疗局部晚期宫颈癌（LACC），我们开发了一种用于CBCT引导放疗（RT）的POTD评估工具。将女性骨盆分割模型（U-Seg3）与一种新颖的定量标准操作程序（qSOP）相结合，以识别最佳和可接受的计划。使用来自39例接受POTD（=11）或非适应性放疗（=28）的LACC患者的计划CT[i]、相应的结构集[ii]和手动勾勒的CBCT[iii]（=226）来开发U-Seg3，这是一种结合深度学习和可变形图像配准技术的算法，用于分割低风险临床靶区（LR-CTV）、高风险CTV（HR-CTV）、膀胱、直肠和肠袋。还开发了一种单通道输入模型（仅iii，U-Seg1）。来自POTD患者的勾勒CBCT被用于：（a）保留用于U-Seg3验证/测试；（b）审核以确定最佳和可接受的计划；（c）用于凭经验推导能使分类准确性最大化的qSOP。对于LR-CTV、HR-CTV、膀胱、直肠和肠，手动轮廓与U-Seg3轮廓之间的中位（四分位间距）骰子相似系数（DSC）分别为0.83[0.80]、0.78[0.13]、0.94[0.05]、0.86[0.09]和0.90[0.05]。除膀胱外，所有结构中的这些系数均显著高于U-Seg1。如果计划满足靶区覆盖阈值（LR-CTV⩾99%，HR-CTV⩾99.8%），qSOP将其分类为可接受，有时较低的LR-CTV覆盖（⩾95%）也被允许。除非能实现显著的膀胱保护，否则将使肠道受照最少的可接受计划视为最佳计划。将U-Seg3嵌入qSOP中，在60例中有46例和57例分别识别出最佳和可接受的计划。U-Seg3在范围和准确性方面均优于U-Seg1以及所有已知的基于CBCT的女性骨盆分割模型（中位DSC改善范围为0.03 - 0.06）。结合U-Seg3和qSOP的工具识别最佳计划的准确性与两名观察者相当。在一种该工具作为第二观察者的实施策略中，可以提高计划选择的信心和决策时间，同时将所需的经过POTD培训的放射技师数量减少50%。
