Oscar Acosta1, Eugenia Mylona2, Mathieu Le Dain2, Camille Voisin2, Thibaut Lizee2, Bastien Rigaud2, Carolina Lafond3, Khemara Gnep3, Renaud de Crevoisier3. 1. INSERM U1099, Rennes, France; Université de Rennes 1 - Laboratoire du Traitement du Signal et de l'Image, France. Electronic address: oscar.acosta@univ-rennes1.fr. 2. INSERM U1099, Rennes, France; Université de Rennes 1 - Laboratoire du Traitement du Signal et de l'Image, France. 3. INSERM U1099, Rennes, France; Université de Rennes 1 - Laboratoire du Traitement du Signal et de l'Image, France; Centre Eugene Marquis, Département de Radiothérapie, Rennes, France.
Abstract
BACKGROUND AND PURPOSE: 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. MATERIALS AND METHODS: 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. RESULTS: 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. CONCLUSION: A multi-atlas-based segmentation method was proposed enabling assessment of the dose within the prostatic urethra.
BACKGROUND AND PURPOSE: 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. MATERIALS AND METHODS: 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 cancerpatients having received 78Gy IMRT to quantify dose to the urethra. RESULTS: 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. CONCLUSION: A multi-atlas-based segmentation method was proposed enabling assessment of the dose within the prostatic urethra.
Authors: Leon Lenchik; Laura Heacock; Ashley A Weaver; Robert D Boutin; Tessa S Cook; Jason Itri; Christopher G Filippi; Rao P Gullapalli; James Lee; Marianna Zagurovskaya; Tara Retson; Kendra Godwin; Joey Nicholson; Ponnada A Narayana Journal: Acad Radiol Date: 2019-08-10 Impact factor: 3.173