目的:MRI在放疗计划中的应用越来越广泛,特别是随着MRI引导放射治疗(MRIgRT)系统的出现。定义前列腺床临床目标体积(CTV)的现有指南显示出相当大的异质性。本研究旨在建立MRI上前列腺床CTV轮廓的基线观察者间变异性(IOV)。制定国际共识指南并评估其对IOV的影响。
方法:参与者在三次MRI扫描中描绘了CTV,从xxxMR-Linac获得,按照他们的正常做法。对放射肿瘤学家的轮廓进行了视觉检查,以进行差异,并使用重叠度量(Dice相似性系数和Cohen'sKappa)根据同时真相和性能水平估计(STAPLE)轮廓对观察者之间的比较进行了评估。距离度量(平均协议距离和豪斯多夫距离)和体积测量。.对前列腺癌根治术后局部复发模式进行了文献综述,并与IOV结果一起提交给参与者。共同制定共识准则,并使用这些准则重复进行IOV评估。
结果:16名放射肿瘤学家的轮廓被纳入最终分析。视觉评价显示出显著的差别优越,下缘和前缘。基线IOV评估表明重叠度量的中等一致性,而体积和距离度量显示更大的可变性。在虚拟会议期间建立了最佳前列腺床CTV边界的共识。后指南发展,观察到IOV下降。最大体积比从4.7下降到3.1,体积变异系数从40%下降到34%。平均Dice相似系数从0.72上升到0.75,平均距离从3.63mm下降到2.95mm。
结论:国际泌尿生殖系统专家存在前列腺床轮廓的观察者间差异,尽管这比以前报道的要低。已经开发了基于MRI的前列腺床轮廓的共识指南,这导致了轮廓一致性的改善。然而,IOV坚持和策略,如教育计划,轮廓地图集的开发和指南的进一步完善可能会导致额外的改进。
OBJECTIVE: The use of magnetic resonance imaging (MRI) in radiotherapy planning is becoming more widespread, particularly with the emergence of MRI-guided radiotherapy systems. Existing guidelines for defining the prostate bed clinical target volume (CTV) show considerable heterogeneity. This study aimed to establish baseline interobserver variability (IOV) for prostate bed CTV contouring on MRI, develop international consensus
guidelines, and evaluate its effect on IOV.
METHODS: Participants delineated the CTV on 3 MRI scans, obtained from the Elekta Unity MR-Linac, as per their normal practice. Radiation oncologist contours were visually examined for discrepancies, and interobserver comparisons were evaluated against simultaneous truth and performance level estimation (STAPLE) contours using overlap metrics (Dice similarity coefficient and Cohen\'s kappa), distance metrics (mean distance to agreement and Hausdorff distance), and volume measurements. A literature review of postradical prostatectomy local recurrence patterns was performed and presented alongside IOV results to the participants.
Consensus guidelines were collectively constructed, and IOV assessment was repeated using these
guidelines.
RESULTS: Sixteen radiation oncologists\' contours were included in the final analysis. Visual evaluation demonstrated significant differences in the superior, inferior, and anterior borders. Baseline IOV assessment indicated moderate agreement for the overlap metrics while volume and distance metrics demonstrated greater variability.
Consensus for optimal prostate bed CTV boundaries was established during a virtual meeting. After
guideline development, a decrease in IOV was observed. The maximum volume ratio decreased from 4.7 to 3.1 and volume coefficient of variation reduced from 40% to 34%. The mean Dice similarity coefficient rose from 0.72 to 0.75 and the mean distance to agreement decreased from 3.63 to 2.95 mm.
CONCLUSIONS: Interobserver variability in prostate bed contouring exists among international genitourinary experts, although this is lower than previously reported.
Consensus guidelines for MRI-based prostate bed contouring have been developed, and this has resulted in an improvement in contouring concordance. However, IOV persists and strategies such as an education program, development of a contouring atlas, and further refinement of the guidelines may lead to additional improvements.