Real-time markerless tumour tracking with patient-specific deep learning using a personalised data generation strategy: proof of concept by phantom study

• Published in: British journal of radiology Vol. 93; no. 1109; p. 20190420
• Main Authors: Takahashi, Wataru, Oshikawa, Shota, Mori, Shinichiro
• Format: Journal Article
• Language: English
• Published: England The British Institute of Radiology 01.05.2020
• Subjects: Deep Learning; Feasibility Studies; Fluoroscopy - methods; Four-Dimensional Computed Tomography - methods; Humans; Image Processing, Computer-Assisted - methods; Lung Neoplasms - radiotherapy; Movement; Phantoms, Imaging
• ISSN: 0007-1285; 1748-880X; 1748-880X
• DOI: 10.1259/bjr.20190420

For real-time markerless tumour tracking in stereotactic lung radiotherapy, we propose a different approach which uses patient-specific deep learning (DL) using a personalised data generation strategy, avoiding the need for collection of a large patient data set. We validated our strategy with digital phantom simulation and epoxy phantom studies. We developed lung tumour tracking for radiotherapy using a convolutional neural network trained for each phantom's lesion by using multiple digitally reconstructed radiographs (DRRs) generated from each phantom's treatment planning four-dimensional CT. We trained tumour-bone differentiation using large numbers of training DRRs generated with various projection geometries to simulate tumour motion. We solved the problem of using DRRs for training and X-ray images for tracking using the training DRRs with random contrast transformation and random noise addition. We defined adequate tracking accuracy as the percentage frames satisfying <1 mm tracking error of the isocentre. In the simulation study, we achieved 100% tracking accuracy in 3 cm spherical and 1.5×2.25×3 cm ovoid masses. In the phantom study, we achieved 100 and 94.7% tracking accuracy in 3 cm and 2 cm spherical masses, respectively. This required 32.5 ms/frame (30.8 fps) real-time processing. We proved the potential feasibility of a real-time markerless tumour tracking framework for stereotactic lung radiotherapy based on patient-specific DL with personalised data generation with digital phantom and epoxy phantom studies. Using DL with personalised data generation is an efficient strategy for real-time lung tumour tracking.