Medical Physics · 1996 · 321 citations · 0 references
MedicineNuclear EngineeringRadiologyBiomedical ImagingRadiation DosimetryRadiation TransportComputed TomographyComputed Tomography PhysicsElectron DosimetryMonte Carlo DosimetryMonte Carlo MethodsMonte Carlo SimulationElectron Dose CalculationMonte Carlo Dose ModelingMonte Carlo Dose SimulationRandom-access MemoryThree-dimensional Dose CalculationTissue Inhomogeneity ModelingTomographyVoxel Dosimetry
A novel electron‑beam dose calculation model has been developed. The model uses a voxel‑based Monte Carlo algorithm that solves electron transport on CT‑defined geometries without precalculated data, requires about 16 MB of RAM, and was benchmarked against EGS4 and the Hogstrom algorithm. The VMC algorithm achieves a 35‑fold speedup over conventional Monte Carlo with negligible accuracy loss, closely matching EGS4 results—particularly near tissue interfaces—while the Hogstrom algorithm underestimates dose by up to 40 %.
A new model for calculating electron beam dose has been developed. The algorithm is based on a two‐ or three‐dimensional geometry defined by computerized tomography (CT) images. The Monte Carlo technique was used to solve the electron transport equation. However, in contrast to conventional Monte Carlo models (EGS4) several approximations and simplifications in the description of elementary electron processes were introduced reducing in this manner the computational time by a factor of about 35 without significant loss in accuracy. The Monte Carlo computer program does not need any precalculated data. The random access memory required is about 16 Mbytes for a 128 2 ×50 matrix, depending on the resolution of the CT cube. The Voxel Monte Carlo model (VMC) was tested in comparison to calculations by EGS4 and the “Hogstrom algorithm” (MDAH) using several fictive phantoms. In all cases a good coincidence has been found between EGS4 and VMC, especially near tissue inhomogeneities, whereas the MDAH algorithm has produced dose underestimations of up to 40%.