An open-source nnU-net algorithm for automatic segmentation of MRI scans in the male pelvis for adaptive radiotherapy

BackgroundAdaptive MRI-guided radiotherapy (MRIgRT) requires accurate and efficient segmentation of organs and targets on MRI scans. Manual segmentation is time-consuming and variable, while deformable image registration (DIR)-based contour propagation may not account for large anatomical changes. Therefore, we developed and evaluated an automatic segmentation method using the nnU-net framework.MethodsThe network was trained on 38 patients (76 scans) with localized prostate cancer and tested on 30 patients (60 scans) with localized prostate, metastatic prostate, or bladder cancer treated at a 1.5 T MRI-linac at our institution. The performance of the network was compared with the current clinical workflow based on DIR. The segmentation accuracy was evaluated using the Dice similarity coefficient (DSC), mean surface distance (MSD), and Hausdorff distance (HD) metrics.ResultsThe trained network successfully segmented all 600 structures in the test set. High similarity was obtained for most structures, with 90% of the contours having a DSC above 0.9 and 86% having an MSD below 1 mm. The largest discrepancies were found in the sigmoid and colon structures. Stratified analysis on cancer type showed that the best performance was seen in the same type of patients that the model was trained on (localized prostate). Especially in patients with bladder cancer, the performance was lower for the bladder and the surrounding organs. A complete automatic delineation workflow took approximately 1 minute. Compared with contour transfer based on the clinically used DIR algorithm, the nnU-net performed statistically better across all organs, with the most significant gain in using the nnU-net seen for organs subject to more considerable volumetric changes due to variation in the filling of the rectum, bladder, bowel, and sigmoid.ConclusionWe successfully trained and tested a network for automatically segmenting organs and targets for MRIgRT in the male pelvis region. Good test results were seen for the trained nnU-net, with test results outperforming the current clinical practice using DIR-based contour propagation at the 1.5 T MRI-linac. The trained network is sufficiently fast and accurate for clinical use in an online setting for MRIgRT. The model is provided as open-source

Comparison of three immobilisation systems for radiation therapy in head and neck cancer

Comparison of three immobilisation systems for radiation therapy in head and neck cance

Plan quality for high-risk prostate cancer treated with high field magnetic resonance imaging guided radiotherapy

Background and purpose: Daily radiotherapy plan adaptation facilitated by a high field magnetic resonance linac (MRL) may potentially reduce the treated volume due to a reduction of the setup uncertainty. However, the technology also imposes limitations to the treatment technique compared to a standard linac. This study investigated the clinical quality of MRL treatment plans against current standard plans using identical planning target volume margins for high-risk prostate cancer patients. Materials and methods: Twenty consecutive patients planned with our current clinical standard TPS and treated with single arc VMAT on standard linacs with 78 Gy in the prostate and 56 Gy for pelvic lymph nodes over 39 fractions were included. In addition, IMRT treatment plans for delivery by a 1.5 T MRL, using standard margins and dose objectives, were made in a dedicated TPS. Mean population dose volume histograms (DVH) and dose metrics were analyzed and clinical plan quality was evaluated by an oncologist. Results: All MRL plans were considered clinically acceptable, and DVH analysis showed an overall high similarity to dose distributions of the clinically delivered plans. Mean target coverage was similar (78.0 Gy vs 77.8 Gy). Small but statistically significant differences were seen in doses to organs at risk; on average MRL plans reduced dose to the bladder (46.2 vs 48.3 Gy) compared to standard plans, while dose was higher to the bowel (29.2 vs 26.6 Gy) and penile bulb (16.5 vs 10.8 Gy). Conclusion: MRL treatment plans were clinically acceptable and similar in quality to the current standard

MR-guided adaptive radiotherapy for bladder cancer

Radiotherapy has an important role in the curative and palliative treatment settings for bladder cancer. As a target for radiotherapy the bladder presents a number of technical challenges. These include poor tumor visualization and the variability in bladder size and position both between and during treatment delivery. Evidence favors the use of magnetic resonance imaging (MRI) as an important means of tumor visualization and local staging. The availability of hybrid systems incorporating both MRI scanning capabilities with the linear accelerator (MR-Linac) offers opportunity for in-room and real-time MRI scanning with ability of plan adaption at each fraction while the patient is on the treatment couch. This has a number of potential advantages for bladder cancer patients. In this article, we examine the technical challenges of bladder radiotherapy and explore how magnetic resonance (MR) guided radiotherapy (MRgRT) could be leveraged with the aim of improving bladder cancer patient outcomes. However, before routine clinical implementation robust evidence base to establish whether MRgRT translates into improved patient outcomes should be ascertained

Awareness and surveillance of radiation treatment schedules reduces head and neck overall treatment time

Background and purpose: Overall treatment time (OTT) is essential for local tumour control and survival in radiotherapy of head and neck cancer (HNC). National radiotherapy guidelines of the Danish Head and Neck Cancer Group (DAHANCA) recommend a maximum OTT of 41 days for moderately accelerated radiation treatment (6 fractions/week) and 48 days for conventional treatment (5 fractions/week). The purpose of this study was to evaluate the effect of surveillance of the radiotherapy course length and treatment gaps in HNC patients to reduce OTT. Methods: The study included 2011 patients with HNC undergoing radical radiation treatment with 66–68 Gy in 33–34 fractions in 2003–2017 at Odense University Hospital. In February 2016, a systematic weekly review by two radiation therapists of all planned treatment courses was introduced to check OTT of individual patients to portend likely breaks or treatment prolongations. Schedules that violated the OTT guidelines were conferred with the responsible radiation oncologist, and treatment rescheduled by treating twice daily to catch up with a delay. Results: The mean length of accelerated treatment courses was reduced from a maximum of 40.9 days in 2007 to 38.3 days in 2017 and from 50.3 days to 45.9 days for conventional courses. The percentage of individual treatment courses that violated the recommended OTT was reduced to 3% of the accelerated treatments and 13% for the conventional treatments. Conclusion: Continuous surveillance of treatment schedules of HNC patients by a brief weekly survey reduced treatment course duration to an extent that was radiobiologically and clinically meaningful. Keywords: Head and neck cancer, Radiotherapy, Overall treatment time, Radiobiology, Workflow management, Health economic

An open-source nnU-net algorithm for automatic segmentation of MRI scans in the male pelvis for adaptive radiotherapy

<p>Data related to the article:</p><p>Front. Oncol.</p><p>Sec. Radiation Oncology</p><p>Volume 13 - 2023 | doi: 10.3389/fonc.2023.1285725</p><p> </p><p>An open-source nnU-net algorithm for automatic segmentation of MRI scans in the male pelvis for adaptive radiotherapy</p><p>Ebbe Laugaard Lorenzen 1,2*, Bahar Celik 1, Nis Sarup1, Lars Dysager3, Rasmus Lübeck Christiansen1, Anders Smedegaard Bertelsen1, Uffe Bernchou1,2, Søren Nielsen Agergaard1, Maximilian Lukas Konrad1, Carsten Brink1,2*, Faisal Mahmood1,2, Tine Schytte2,3, Christina Junker Nyborg3</p><p>1 Laboratory of Radiation Physics, Department of Oncology, Odense University Hospital, J. B. Winsløws Vej 4, 5000 Odense C, Denmark </p><p>2 Department of Clinical Research, University of Southern Denmark, J.B. Winsløws Vej 19 3., 5000 Odense C, Denmark</p><p>3 Department of Oncology, Odense University Hospital, J. B. Winsløws Vej 4, 5000 Odense C, Denmark</p><p>* Correspondence: </p><p>Ebbe Laugaard Lorenzen</p><p>[email protected]</p><p>Carsten Brink </p><p>[email protected]</p><p> </p&gt

Automatic treatment planning facilitates fast generation of high-quality treatment plans for esophageal cancer

<p><b>Background:</b> The quality of radiotherapy planning has improved substantially in the last decade with the introduction of intensity modulated radiotherapy. The purpose of this study was to analyze the plan quality and efficacy of automatically (AU) generated VMAT plans for inoperable esophageal cancer patients.</p> <p><b>Material and Methods:</b> Thirty-two consecutive inoperable patients with esophageal cancer originally treated with manually (MA) generated volumetric modulated arc therapy (VMAT) plans were retrospectively replanned using an auto-planning engine. All plans were optimized with one full 6MV VMAT arc giving 60 Gy to the primary target and 50 Gy to the elective target. The planning techniques were blinded before clinical evaluation by three specialized oncologists. To supplement the clinical evaluation, the optimization time for the AU plan was recorded along with DVH parameters for all plans.</p> <p><b>Results:</b> Upon clinical evaluation, the AU plan was preferred for 31/32 patients, and for one patient, there was no difference in the plans. In terms of DVH parameters, similar target coverage was obtained between the two planning methods. The mean dose for the spinal cord increased by 1.8 Gy using AU (<i>p</i> = .002), whereas the mean lung dose decreased by 1.9 Gy (<i>p</i> < .001). The AU plans were more modulated as seen by the increase of 12% in mean MUs (<i>p</i> = .001). The median optimization time for AU plans was 117 min.</p> <p><b>Conclusions:</b> The AU plans were in general preferred and showed a lower mean dose to the lungs. The automation of the planning process generated esophageal cancer treatment plans quickly and with high quality.</p