Electron density maps must be accurately estimated to achieve valid dose calculation in MR-only radiotherapy. The goal of this study is to assess whether two deep learning models, the conditional generative adversarial network (cGAN) and the cycle-consistent generative adversarial network (cycleGAN), can generate accurate abdominal synthetic CT (sCT) images from 0.35T MR images for MR-only liver radiotherapy. A retrospective study was performed using CT images and 0.35T MR images of 12 patients with liver (n=8) and non-liver abdominal (n=4) cancer. CT images were deformably registered to the corresponding MR images to generate deformed CT (dCT) images for treatment planning. Both cGAN and cycleGAN were trained using MR and dCT transverse slices. Four-fold cross-validation testing was conducted to generate sCT images for all patients. The HU prediction accuracy was evaluated by voxel-wise similarity metric between each dCT and sCT image for all 12 patients. dCT-based and sCT-based dose distributions were compared using gamma and dose-volume histogram (DVH) metric analysis for 8 liver patients. sCTcycleGAN achieved the average mean absolute error (MAE) of 94.1 HU, while sCTcGAN achieved 89.8 HU. In both models, the average gamma passing rates within all volumes of interest were higher than 95% using a 2%, 2 mm criterion, and 99% using a 3%, 3 mm criterion. The average differences in the mean dose and DVH metrics were within +/-0.6% for the planning target volume and within +/-0.15% for evaluated organs in both models. Results demonstrated that abdominal sCT images generated by both cGAN and cycleGAN achieved accurate dose calculation for 8 liver radiotherapy plans. sCTcGAN images had smaller average MAE and achieved better dose calculation accuracy than sCTcyleGAN images. More abdominal patients will be enrolled in the future to further evaluate two models.
An MRI-only adaptive radiotherapy (ART) workflow is desirable for managing interfractional changes in anatomy, but producing synthetic CT (sCT) data through paired data-driven deep learning (DL) for abdominal dose calculations remains a challenge due to the highly variable presence of intestinal gas. We present the preliminary dosimetric evaluation of our novel approach to sCT reconstruction that is well suited to handling intestinal gas in abdominal MRI-only ART. We utilize a paired data DL approach enabled by the intensity projection prior, in which well-matching training pairs are created b…
Amsterdam UMC, University of Amsterdam（阿姆斯特丹大学阿姆斯特丹大学医学中心）；University Medical Center Utrecht（乌得勒支大学医学中心）；Princess Màxima Center for Pediatric Oncology（玛克西玛公主儿科肿瘤中心）；Princess Margaret Cancer Centre（玛格丽特公主癌症中心）
To study radiotherapy-related adverse effects, detailed dose information (3D distribution) is needed for accurate dose-effect modeling. For childhood cancer survivors who underwent radiotherapy in the pre-CT era, only 2D radiographs were acquired, thus 3D dose distributions must be reconstructed from limited information. State-of-the-art methods achieve this by using 3D surrogate anatomies. These can lack personalization and lead to coarse reconstructions. We present and validate a surrogate-free dose reconstruction method based on Machine Learning (ML). Abdominal planning CTs ($n$=142) of rec…
SynthRAD2025 Grand Challenge dataset: generating synthetic CTs for radiotherapy
LMU University Hospital, LMU Munich（慕尼黑大学附属医院，慕尼黑大学）；Radboud University Medical Center（拉德堡德大学医学中心）；University Medical Center Groningen, University of Groningen（格罗宁根大学医学中心，格罗宁根大学）；University Hospital of Cologne（科隆大学附属医院）；University Medical Center Utrecht（乌得勒支大学医学中心）；German Cancer Consortium (DKTK)（德国癌症联盟）；Bavarian Cancer Research Center (BZKF)（巴伐利亚癌症研究中心）；Skåne University Hospital（斯科讷大学医院）；Lund University（隆德大学）；Deutsches Krebsforschungszentrum (DKFZ)（德国癌症研究中心）
Purpose: CBCT-based adaptive radiotherapy requires daily images for accurate dose calculations. This study investigates the feasibility of applying a single convolutional network to facilitate CBCT-to-CT synthesis for head-and-neck, lung, and breast cancer patients. Methods: Ninety-nine patients diagnosed with head-and-neck, lung or breast cancer undergoing radiotherapy with CBCT-based position verification were included in this study. CBCTs were registered to planning CTs according to clinical procedures. Three cycle-consistent generative adversarial networks (cycle-GANs) were trained in an u…
Overcoming data scarcity through multi-center federated learning for organs-at-risk segmentation in pediatric upper abdominal radiotherapy
Princess Máxima Centre for Pediatric Oncology；University Medical Centre Utrecht；Centre for Image Sciences, University Medical Centre Utrecht；University Hospital Heidelberg；University Medical Center Utrecht；Division Imaging & Cancer, University Medical Center Utrecht；Division of Pediatric Radiology, Department of Diagnostic and Interventional Radiology, University Hospital Heidelberg；Wilhelmina Children’s Hospital-Division of CHILD HEALTH, University Medical Centre Utrecht, University of Utrecht
Centrum Wiskunde & Informatica（数学与计算机科学国家研究所）；Amsterdam UMC, University of Amsterdam（阿姆斯特丹大学阿姆斯特丹大学医学中心）；Delft University of Technology（代尔夫特理工大学）
Machine Learning (ML) is proving extremely beneficial in many healthcare applications. In pediatric oncology, retrospective studies that investigate the relationship between treatment and late adverse effects still rely on simple heuristics. To assess the effects of radiation therapy, treatment plans are typically simulated on phantoms, i.e., virtual surrogates of patient anatomy. Currently, phantoms are built according to reasonable, yet simple, human-designed criteria. This often results in a lack of individualization. We present a novel approach that combines imaging and ML to build individ…
Purpose: To assess the fiducial motion in abdominal stereotactic body radiotherapy (SBRT) using the cone-beam computed tomography (CBCT) projections acquired for pre-treatment patient set-up. Materials and Methods: Pre-treatment CBCT projections and anterior-posterior (AP) and lateral (LAT) pair of fluoroscopic sequences of 7 pancreatic and 6 liver SBRT patients with implanted fiducials were analyzed for 49 treatment fractions retrospectively. A tracking algorithm based on template matching and sequential stereo triangulation algorithms was used to track the fiducials in the CBCT projections a…
Intrafraction motion can play a pivotal role in the success of abdominal and thoracic radiation therapy. Hybrid magnetic resonance-guided radiotherapy systems have the potential to control for intrafraction motion. Recently, we introduced an MRI sequence capable of acquiring real-time cine imaging in two orthogonal planes (SOPI). We extend SOPI here to permit dynamic updating of slice positions in one plane while keeping the other plane position fixed. In this implementation, cine images from the static plane are used for motion monitoring and as image navigators to sort stepped images in the …
Currently, MRI-only radiotherapy (RT) eliminates some of the concerns about using CT images in RT chains such as the registration of MR images to a separate CT, extra dose delivery, and the additional cost of repeated imaging. However, one remaining challenge is that the signal intensities of MRI are not related to the attenuation coefficient of the biological tissue. This work compares the performance of two state-of-the-art deep learning models; a generative adversarial network (GAN) and a residual network (ResNet) for synthetic CTs (sCT) generation from MR images. The brain MR and CT images…
DoseRAD2026 Challenge dataset: AI accelerated photon and proton dose calculation for radiotherapy
Department of Radiation Oncology, LMU University Hospital, LMU Munich, Munich, Germany（路德维希-马克西米利安慕尼黑大学医学院放射肿瘤科，慕尼黑大学医院，慕尼黑，德国）；Division of Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany（放射肿瘤学中的医学物理部门，德国癌症研究中心（DKFZ），海德堡，德国）；National Center for Radiation Research in Oncology (NCRO), Heidelberg Institute for Radiation Oncology (HIRO), Heidelberg, Germany（肿瘤放射研究国家中心（NCRO），海德堡放射肿瘤学研究所（HIRO），海德堡，德国）；GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany（重离子研究中心GSI，生物物理部门，达姆施塔特，德国）；Department of Physics and Astronomy, Heidelberg University, Heidelberg, Germany（海德堡大学物理与天文学系，海德堡，德国）；Institute of Biomedical Engineering, Karlsruhe Institute of Technology, Baden-Württemberg, Germany（生物医学工程研究所，卡尔斯鲁厄理工学院，巴登-符腾堡，德国）；Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands（放射治疗科，乌得勒支大学医学中心，乌得勒支，荷兰）；Department of Radiation Oncology, Amsterdam UMC location Vrije Universiteit Amsterdam, Cancer Center Amsterdam, Cancer Treatment and Quality of Life, Amsterdam, Netherlands（放射肿瘤学系，阿姆斯特丹自由大学阿姆斯特丹校区，阿姆斯特丹癌症中心，癌症治疗与生活质量，阿姆斯特丹，荷兰）；Center for Proton Therapy, Paul Scherrer Institute (PSI), Villigen, Switzerland（质子治疗中心，瑞士保罗·谢尔研究所（PSI），维利根，瑞士）；Department of Radiation Oncology, University Hospital Heidelberg, Heidelberg, Germany（放射肿瘤学系，海德堡大学医院，海德堡，德国）；Radiation Physics, Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden（放射物理，血液学、肿瘤学和放射物理部门，斯德哥尔摩大学医院，吕勒奥，瑞典）；Delft University of Technology, Department of Radiation Science and Technology, Delft, Netherlands（代尔夫特理工大学，辐射科学与技术系，代尔夫特，荷兰）；Radformation Inc., New York, US（Radformation公司，纽约，美国）
Generating synthetic computed tomography for radiotherapy: SynthRAD2025 challenge report
Radiation Physics, Department of Hematology, Oncology；Radiation Physics, Skåne University Hospital, Lund, Sweden；Medical Radiation Physics, Department of Clinical Sciences Lund, Lund University, Lund, Sweden；Radiotherapy Department, University Medical Center Utrecht, Utrecht, The Netherlands；Computational Imaging Group for MR Diagnostics \& Therapy, University Medical Center Utrecht, Utrecht, The Netherlands；Division of Medical Physics in Radiation Oncology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany；Heidelberg Institute for Radiation Oncology (HIRO)；National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany；Department of Radiation Oncology；Cyberknife Center, University Hospital of Cologne, Cologne, Germany；Department of Radiation Oncology, Radboud University Medical Center, Nijmegen, The Netherlands；Department of Radiation Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands；Department of Radiation Oncology, LMU University Hospital, LMU Munich, Munich, Germany；Bavarian Cancer Research Center (BZKF), Munich, Germany；Australian eHealth Research Center, CSIRO, Brisbane, Australia；School of Computer Science, University of Sydney, Sydney, Australia；Department of Orthodontics；Pattern Recognition Lab, FAU Erlangen-Nuremberg, Germany；RIKEN Center for Integrative Medical Sciences, Tokyo, Japan；Erasmus Mundus Joint Master's Degree IPCVai, University of Bordeaux, France；Computer Science, Huazhong University of Science；Huazhong University of Science；Canon Medical Systems (China) CO., LTD., Beijing, China；Department of Radiation Oncology, Inselspital, Bern University Hospital；University of Bern, Bern, Switzerland
To achieve magnetic resonance (MR)-only radiotherapy, a method needs to be employed to estimate a synthetic CT (sCT) for generating electron density maps and patient positioning reference images. We investigated 2D and 3D convolutional neural network (CNN) methods to generate a male pelvic sCT using a T1-weighted MR image. A retrospective study was performed using CTs and T1-weighted MR images of 20 prostate cancer patients. The proposed 2D CNN model, which contained 27 convolutional layers, was modified from the SegNet for better performance. 3D version of the CNN model was also developed. Bo…
