M Rilling^1,2,3,4*, S Thibault^1,2 , L Archambault^1,3,4 , (1) Departement de physique, de genie physique et d'optique, Universite Laval, Quebec, QC, Canada (2) Centre d'optique, photonique et laser, Quebec, QC, Canada (3) Centre de recherche sur le cancer, Quebec, QC, Canada (4) Centre de recherche du CHU de Quebec-Universite Laval - Axe oncologie, Quebec, QC, Canada

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  M Rilling

(Thursday, 7/18/2019) 10:00 AM - 12:00 PM

Room: 301

Purpose: To develop a versatile and flexible simulation method using an optical design software for designing imaging-based tomography systems and to validate the complete workflow for reconstructing test dose distributions, within the context of 3D scintillation dosimetry.

Methods: The simulation method was developed using Zemax OpticStudio®, a software for designing virtual prototypes of optical systems. Exploiting OpticStudio’s ray tracing features, three systematic key steps were implemented with the end goal of imaging-based 3D emission-computed tomography: (1) modeling different types of imaging systems and viewing positions; (2) computing their respective projection matrices, and (3) simulating photorealistic images of a fluorescent light pattern emitted within a plastic scintillator volume. To validate, 3D benchmark and clinical spinal SBRT dose distributions were reconstructed using simulated images as input projections within a 60x60x60-mm³ volume discretized at a resolution of 1.5-mm. Without loss of generality, reconstructions were obtained using an inverse tomographic maximum likelihood-expectation maximization algorithm. The reconstruction quality was assessed using 2D and 3D correlation coefficients.

Results: The method enabled the simulation and tomographic modeling of three distinct imaging systems: a standard conventional camera and two focused plenoptic cameras, one with a single focal-length orthogonal microlens array and one with a triple focal-length hexagonal microlens array. The tomographic performance could be compared based on system type and number of projections. In particular, for all systems, an average 32% increase in 3D correlation was observed when using 2 vs 1 orthogonal projections, whereas an average 3% increase resulted from adding a third orthogonal projection. Moreover, the plenoptic cameras were not found to significantly outperform the conventional camera.

Conclusion: By taking advantage of optical design tools, we've shown a streamlined and versatile workflow to conceive and compare scintillator-based dose detectors. Our work paves the way for the rigorous optimization of a new generation of 3D dosimetry systems.

Funding Support, Disclosures, and Conflict of Interest: Madison Rilling was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) Alexander-Graham-Bell doctoral scholarship. This research was supported by the NSERC Industrial Research Chair in Optical Design.

Keywords

3D, Scintillators, Dosimetry

Taxonomy

TH- Radiation dose measurement devices: scintillators

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