Improving Proton Dose Calculation Accuracy by Using Deep Learning

• Published in: Machine learning: science and technology Vol. 2; no. 1; p. 15017
• Main Authors: Wu, Chao, Nguyen, Dan, Xing, Yixun, Montero, Ana Barragan, Schuemann, Jan, Shang, Haijiao, Pu, Yuehu, Jiang, Steve
• Format: Journal Article
• Language: English
• Published: England IOP Publishing 01.03.2021
• Subjects: Accuracy; Computed tomography; Datasets; Deep learning; Dosage; Liver; Lungs; Model accuracy; Model testing; Monte Carlo; pencil beam; Pencil beams; Prostate; proton dose calculation; Protons; Training; Tumors; Workflow; Deep learning; Pencil beam; Monte Carlo; Proton dose calculation
• ISSN: 2632-2153; 2632-2153
• DOI: 10.1088/2632-2153/abb6d5

Pencil beam (PB) dose calculation is fast but inaccurate due to the approximations when dealing with inhomogeneities. Monte Carlo (MC) dose calculation is the most accurate method but it is time consuming. The aim of this study was to develop a deep learning model that can boost the accuracy of PB dose calculation to the level of MC dose by converting PB dose to MC dose for different tumor sites. The proposed model uses the PB dose and CT image as inputs to generate the MC dose. We used 290 patients (90 head and neck, 93 liver, 75 prostate and 32 lung) to train, validate, and test the model. For each tumor site, we performed four numerical experiments to explore various combinations of training datasets. Training the model on data from all tumor sites together and using the dose distribution of each individual beam as input yielded the best performance for all four tumor sites. The average gamma passing rate (1mm/1%) between the converted and the MC dose was 92.8%, 92.7%, 89.7% and 99.6% for head and neck, liver, lung, and prostate test patients, respectively. The average dose conversion time for a single field was less than 4 seconds. The trained model can be adapted to new datasets through transfer learning. Our deep learning-based approach can quickly boost the accuracy of PB dose to that of MC dose. The developed model can be added to the clinical workflow of proton treatment planning to improve dose calculation accuracy.