Yedekci Yagiz, Gültekin Melis, Sarı Sezin Yuce, Yıldız Ferah
Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
J Contemp Brachytherapy. 2022 Feb;14(1):72-79. doi: 10.5114/jcb.2022.112814. Epub 2022 Jan 23.
To investigate the effectiveness of deformable image registration (DIR)-based automatic contouring for tandem-ring (T-R) or tandem-ovoid (T-O) 3-dimensional computed tomography (CT)-based image-guided brachytherapy (IGBT).
CT images of 28 patients with intact cervical cancer were retrospectively analyzed. Selected group had T-R or T-O insertion for IGBT. Hybrid DIR was performed between first fraction CT and subsequent CTs for IGBT. First IGBT CT images were reference images. All DIRs were performed based on these first IGBT CT scans. Contour similarities between manual and automated segmentations were evaluated with dice similarity coefficient (DSC) score. Mean volumes of the structures were delineated manually and automatically compared. Finally, dosimetric comparisons were performed in order to obtain how contour differences affect the doses to target and organs at risk (OARs).
In general, mean volumes of the automatic contours were larger than manual contours for both T-R and T-O insertions. However, the difference in volume was statistically significant for the small bowel only ( < 0.05 and < 0.01 for T-R and T-O, respectively). The DSC scores were small for the small bowel and the sigmoid in both applicator sets. When the two different applicator sets were compared, the performance of DIR-based contour propagation for the rectum was worse in T-O compared to T-R application. Dosimetric comparisons showed that volume differences between the manual and propagated contours did not affect dose-volume parameters. The treatment plans based on manually contoured targets also well-covered DIR contours. The average time for DIR was 2.0 ±0.1 minutes per fraction compared to 14.0 ±0.4 minutes in manual contouring ( < 0.001).
DIR-based automatic contouring of the structures seems successful for both the T-R and T-O applications in cervical IGBT. DIR significantly decreased the time for contouring. Our results indicate that automatic contouring in IGBT is safe and time-saving.
探讨基于可变形图像配准（DIR）的自动轮廓勾画在基于三维计算机断层扫描（CT）的串联环（T-R）或串联椭圆体（T-O）图像引导近距离放射治疗（IGBT）中的有效性。
回顾性分析28例宫颈癌完整患者的CT图像。选定的组接受了用于IGBT的T-R或T-O植入。在首次分割CT与后续用于IGBT的CT之间进行混合DIR。首次IGBT CT图像作为参考图像。所有DIR均基于这些首次IGBT CT扫描进行。用骰子相似系数（DSC）评分评估手动分割与自动分割之间的轮廓相似性。手动和自动勾勒结构的平均体积并进行比较。最后，进行剂量学比较，以了解轮廓差异如何影响靶区和危及器官（OAR）的剂量。
总体而言，对于T-R和T-O植入，自动轮廓的平均体积均大于手动轮廓。然而，仅小肠的体积差异具有统计学意义（T-R和T-O分别为<0.05和<0.01）。在两种施源器装置中，小肠和乙状结肠的DSC评分均较低。比较两种不同的施源器装置时，与T-R应用相比，T-O中基于DIR的直肠轮廓传播性能较差。剂量学比较表明，手动轮廓与传播轮廓之间的体积差异不影响剂量体积参数。基于手动勾勒靶区的治疗计划也能很好地覆盖DIR轮廓。DIR的平均时间为每分割2.0±0.1分钟，而手动轮廓勾画为14.0±0.4分钟（<0.001）。
基于DIR的结构自动轮廓勾画在宫颈癌IGBT的T-R和T-O应用中似乎都是成功的。DIR显著减少了轮廓勾画时间。我们的结果表明，IGBT中的自动轮廓勾画是安全且省时的。
