Development of a 3D Dose Reconstruction Algorithm for Volumetric Plastic Scintillation Detectors
Abstract
Purpose
To develop a 3D dose reconstruction algorithm capable of generating volumetric dose distributions measured with large plastic scintillation detectors irradiated with photon, electron, and proton beams used in radiation therapy.
Methods
An algorithm was developed to reconstruct 3D dose distributions measured with a volumetric, tissue-equivalent plastic scintillator detector. This algorithm is based on the back-projection of the 2D-dose distributions obtained from the images of the scintillation light captured with cameras that are positioned around the plastic scintillator. The cameras were installed on multiple sides of a large plastic scintillator block (20 × 30 × 30 cm³) and housed in a light-tight chamber to collect simultaneously the scintillation light induced by radiation.
Results
The reconstructed 3D dose distributions demonstrated the feasibility and effectiveness of plastic scintillators as large, water-equivalent volumetric dosimeters. Dose profiles along the lateral (X and Y) directions and depth-dose curves were simultaneously extracted from a single-shot irradiation using photon, electron or proton beams. For proton beams, beam ranges were accurately determined from the reconstructed volumetric dose distributions for each beam used in the treatment of different sites. Although the plastic scintillators provided a continuous medium with inherently high spatial resolution, the reconstructed dose resolution was limited by the camera digitization resolution (0.25 mm) of the dose projections. Dose linearity was influenced by the camera response and sensitivity to the different levels of the emitted scintillation light. The reconstruction accuracy depended on the optical transmission properties of the scintillator and the number of the dose projections obtained by the cameras surrounding the detector.
Conclusion
Three-dimensional dose reconstruction using plastic scintillation detectors shows strong potential to advance the dosimetry techniques in radiation therapy. These detectors offer tissue-equivalent, large-volume 3D dose measurements with high spatial resolution and enable comprehensive quality assurance for therapeutic photon, electron, and proton beams.