Table 2 Features and capabilities of the non-adaptive (na-) and the adaptive (a-) pMMC
From: Adaptive step size algorithm to increase efficiency of proton macro Monte Carlo dose calculation
na-pMMC | a-pMMC | |
|---|---|---|
Step size | Restricted by varying HU values | Adaptive choice of macro step |
Energy deposition | Linear rescaling of deposited energy depending on covered fraction of macro step | Stopping power approximation over multiple voxels of varying HU value |
Trajectory approximation | Hinge step, but macro step is interrupted at voxel boundary of varying HU value | Hinge step at 30% of macro step size, passes multiple voxels of varying HU value |
Dose calculation accuracy | within 1% or 1 mm compared to full MC | |
Efficiency: homogeneous geometries | very good | |
Efficiency: inhomogeneous geometries | limited | very good |