INSERM U1099, Rennes, France; Université de Rennes 1 - Laboratoire du Traitement du Signal et de l'Image, France.
INSERM U1099, Rennes, France; Université de Rennes 1 - Laboratoire du Traitement du Signal et de l'Image, France.
Radiother Oncol. 2017 Dec;125(3):492-499. doi: 10.1016/j.radonc.2017.09.015. Epub 2017 Oct 12.
Segmentation of intra-prostatic urethra for dose assessment from planning CT may help explaining urinary toxicity in prostate cancer radiotherapy. This work sought to: i) propose an automatic method for urethra segmentation in CT, ii) compare it with previously proposed surrogate models and iii) quantify the dose received by the urethra in patients treated with IMRT.
A weighted multi-atlas-based urethra segmentation method was devised from a training data set of 55 CT scans of patients receiving brachytherapy with visible urinary catheters. Leave-one-out cross validation was performed to quantify the error between the urethra segmentation and the catheter ground truth with two scores: the centerlines distance (CLD) and the percentage of centerline within a certain distance from the catheter (PWR). The segmentation method was then applied to a second test data set of 95 prostate cancer patients having received 78Gy IMRT to quantify dose to the urethra.
Mean CLD was 3.25±1.2mm for the whole urethra and 3.7±1.7mm, 2.52±1.5mm, and 3.01±1.7mm for the top, middle, and bottom thirds, respectively. In average, 53% of the segmented centerlines were within a radius<3.5mm from the centerline ground truth and 83% in a radius<5mm. The proposed method outperformed existing surrogate models. In IMRT, urethra DVH was significantly higher than prostate DVH from V74Gy to V79Gy.
A multi-atlas-based segmentation method was proposed enabling assessment of the dose within the prostatic urethra.
从计划 CT 中对前列腺内尿道进行分割，以评估剂量，可能有助于解释前列腺癌放射治疗中的尿毒性。本研究旨在：i）提出一种 CT 自动尿道分割方法，ii）与之前提出的替代模型进行比较，iii）量化接受调强放疗（IMRT）的患者的尿道接受的剂量。
从接受近距离放射治疗且可见导尿管的 55 例 CT 扫描患者的训练数据集设计了一种基于加权多图谱的尿道分割方法。采用留一法交叉验证来量化尿道分割与导管金标准之间的误差，使用两个指标：中心线距离（CLD）和导管中心线一定距离内的中心线百分比（PWR）。然后，将该分割方法应用于接受 78Gy IMRT 的 95 例前列腺癌患者的第二个测试数据集，以量化尿道的剂量。
整个尿道的平均 CLD 为 3.25±1.2mm，尿道顶部、中部和底部的 CLD 分别为 3.7±1.7mm、2.52±1.5mm 和 3.01±1.7mm。平均而言，53%的分割中心线位于距中心线金标准<3.5mm 的半径内，83%位于<5mm 的半径内。与现有的替代模型相比，所提出的方法表现更好。在 IMRT 中，从 V74Gy 到 V79Gy，尿道剂量-体积直方图（DVH）显著高于前列腺 DVH。
提出了一种基于多图谱的分割方法，可评估前列腺尿道内的剂量。
