Hardware Accelerated Image Registration and Dose Calculation for Adaptive Radiation Therapy
Purpose/Objectives: Adaptive radiation therapy (ART) is a
process to improve radiation treatment by adaptively monitoring treatment
variations and incorporate them to re-optimize the treatment plan during the
course of treatment. A critical requirement of ART is the knowledge of the
anatomical changes as well as the actual dose delivered to the patient during
the course of treatment. While cone-beam CT (CBCT) is typically used to
minimize the patient setup error and monitor daily anatomical changes, its poor
quality impedes accurate segmentation of the target structures and the dose
computation. We developed an integrated ART software platform that combines
fast and accurate image registration, segmentation, and dose
computation/accumulation methods. The developed platform automatically links
patient images, radiotherapy plan, beam and dosimetric parameters, and daily
treatment information, thus providing an efficient ART workflow.
Methods: The proposed system consists of three key
components; 1) deformable image registration (DIR), 2) automatic segmentation,
and 3) dose computation/accumulation. The computationally intensive modules
including DIR and dose computation have been parallelized and implemented on
graphic processing units (GPUs). All required patient-specific data including
the planning CT (pCT) with contours, daily cone-beam CTs, and treatment plan
are automatically queried and retrieved from their own databases to our
platform. To improve the accuracy of DIR between the planning CT and CBCTs, we
iteratively correct CBCT intensities by matching local intensity histograms in
conjunction with the DIR process. The GPU-accelerated double force demons
algorithm is employed for DIR. Segmentation for daily CBCT is then obtained by
propagating contours from the pCT using the displacement vector field. Daily
dose delivered to the patient is then computed on the registered pCT by a
GPU-accelerated superposition/convolution algorithm. Finally, computed daily
doses are accumulated to show the total delivered dose to
date.
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