Feasibility and analysis of CNN‐based candidate beam generation for robotic radiosurgery

Abstract

Purpose: Robotic radiosurgery offers the flexibility of a robotic arm to enable high conformity to the target and a steep dose gradient. However, treatment planning becomes a computationally challenging task as the search space for potential beam directions for dose delivery is arbitrarily large. We propose an approach based on deep learning to improve the search for treatment beams. Methods: In clinical practice, a set of candidate beams generated by a randomized heuristic forms the basis for treatment planning. We use a convolutional neural network to identify promising candidate beams. Using radiological features of the patient, we predict the influence of a candidate beam on the delivered dose individually and let this prediction guide the selection of candidate beams. Features are represented as projections of the organ structures which are relevant during planning. Solutions to the inverse planning problem are generated for random and CNN-predicted candidate beams. Results: The coverage increases from 95.35% to 97.67% for 6000 heuristically and CNN-generated candidate beams, respectively. Conversely, a similar coverage can be achieved for treatment plans with half the number of candidate beams. This results in a patient-dependent reduced averaged computation time of 20.28%-45.69%. The number of active treatment beams can be reduced by 11.35% on average, which reduces treatment time. Constraining the maximum number of candidate beams per beam node can further improve the average coverage by 0.75 percentage points for 6000 candidate beams. Conclusions: We show that deep learning based on radiological features can substantially improve treatment plan quality, reduce computation runtime, and treatment time compared to the heuristic approach used in clinics.

Comparing Multi-Objective Local Search Algorithms for the Beam Angle Selection Problem

“…Computed beam fitness values are used to indicate the next best beam to add to the BAC. The authors of [43] propose an approach also based on deep learning to improve the beam selection process. They use a convolutional neural network to identify promising candidate beams by using the radiological features of the patients.…”

“…They use a convolutional neural network to identify promising candidate beams by using the radiological features of the patients. They argue that they can predict the influence of a candidate beam on the delivered dose individually and let this prediction guide the selection of candidate beams [43]. The same authors extend their approach to multiple criteria in [44].…”

“…(d) Cumulative hypervolume for all algorithms for semi-random initial BACs (14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29). (e) Hypervolume for all algorithms for random initial BACs (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44). (f) Cumulative hypervolume for all algorithms for random initial BACs (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44).…”

“…(e) Hypervolume for all algorithms for random initial BACs (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44). (f) Cumulative hypervolume for all algorithms for random initial BACs (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44).…”

Multicriterial CNN based beam generation for robotic radiosurgery of the prostate

“…In this paper, we investigate the multicriterial aspect of treatment planning on the CNN based candidate beam generation. We extend an earlier approach [9] and present different setups to train CNNs using radiological features for predicting each beam's influence on the dose with various clinical goals. We use these predictions to select new candidate beams, improving plan quality while using fewer candidate beams.…”