RIDOS: A new system for online computation of the delivered dose distributions in scanning ion beam therapy

Abstract

Purpose: To describe a new system for scanned ion beam therapy, named RIDOS (Real-time Ion DOse planning and delivery System), which performs real time delivered dose verification integrating the information from a clinical beam monitoring system with a Graphic Processing Unit (GPU) based dose calculation in patient Computed Tomography.Methods: A benchmarked dose computation algorithm for scanned ion beams has been parallelized and adapted to run on a GPU architecture. A workstation equipped with a NVIDIA GPU has been interfaced through a National Instruments PXI-crate with the dose delivery system of the Italian National Center of Oncological Hadrontherapy (CNAO) to receive in real-time the measured beam parameters. Data from a patient monitoring system are also collected to associate the respiratory phases with each spot during the delivery of the dose. Using both measured and planned spot properties, RIDOS evaluates during the few seconds of inter-spill time the cumulative delivered and prescribed dose distributions and compares them through a fast γ-index algorithm.Results: The accuracy of the GPU-based algorithms was assessed against the CPU-based ones and the differences were found below 1‰. The cumulative planned and delivered doses are computed at the end of each spill in about 300ms, while the dose comparison takes approximatively 400ms. The whole operation provides the results before the next spill starts. Conclusions: RIDOS system is able to provide a fast computation of the delivered dose in the inter-spill time of the CNAO facility and allows to monitor online the dose deposition accuracy all along the treatment.

Current and Future Technologies of the CNAO Dose Delivery System

“…A rapid software tool for dose reconstruction was developed in the framework of the RIDOS INFN project [20]. This tool exploits the use of a Graphic Processing Unit (GPU) and a Treatment Planning System, developed in-house, for proton and carbon ion therapy [34].…”

“…Additionally, a fast image deformation algorithm has been developed and tested independently [20] to deform the dose of each spill on points of the reference CT used by the TPS. The cumulative dose distributions can be computed to be compared with the planned one.…”

“…Additionally, details are provided on the treatment data from the DDS to other systems, such as the range verification system delivered in the INnovative Solution for In-beam Dosimetry in hadronthErapy (INSIDE) project [17]. The second section describes two 4D solutions investigated at CNAO to provide the DDS with new features for treating moving targets: multi-phase 4D dose delivery [18], [19] and online dose reconstruction [20].…”