Abstract
Mesh-type and voxel-based computational phantoms comprise the current state-of-the-art for internal dose assessment via Monte Carlo simulations, but excel in different aspects, with mesh-type phantoms offering advantages over their voxel counterparts in terms of their flexibility and realistic representation of detailed patient- or subject-specific anatomy. We have developed PARaDIM, a freeware application for implementing tetrahedral mesh-type phantoms in absorbed dose calculations via the Particle and Heavy Ion Transport code System (PHITS). It considers all medically relevant radionuclides including alpha, beta, gamma, positron, and Auger/conversion electron emitters, and handles calculation of mean dose to individual regions, as well as 3D dose distributions for visualization and analysis in a variety of medical imaging softwares. This work describes the development of PARaDIM, documents the measures taken to test and validate its performance, and presents examples to illustrate its uses. Methods: Human, small animal, and cell-level dose calculations were performed with PARaDIM and the results compared with those of widely accepted dosimetry programs and literature data. Several tetrahedral phantoms were developed or adapted using computer-aided modeling techniques for these comparisons. Results: For human dose calculations, agreement of PARaDIM with OLINDA 2.0 was good – within 10-20% for most organs – despite geometric differences among the phantoms tested. Agreement with MIRDcell for cell-level S-value calculations was within 5% in most cases. Conclusion: PARaDIM extends the use of Monte Carlo dose calculations to the broader community in nuclear medicine by providing a user-friendly graphical user interface for calculation setup and execution. PARaDIM leverages the enhanced anatomical realism provided by advanced computational reference phantoms or bespoke image-derived phantoms to enable improved assessments of radiation doses in a variety of radiopharmaceutical use cases, research, and preclinical development.
- Radiation Safety
- Radiobiology/Dosimetry
- Radiopharmaceuticals
- PARaDIM
- PHITS
- dosimetry
- phantom
- tetrahedral mesh
- Copyright © 2019 by the Society of Nuclear Medicine and Molecular Imaging, Inc.