1997 Volume 46 Issue 3 Pages 154-160
In radiotherapy due to administration of radionuclides, accurate estimates of three-dimensional (3D) absorbed dose distributions of target regions can be performed using a 3D dose matrix convolution method which has already been developed based on a voxel based calculation algorithm by the authors.
The purpose of this study is to elucidate the influence of unit voxel sizes of cumulated radioactivity distributions of beta-emitting radionuclides on 3D absorbed dose estimates.
Computer simulations were performed using cubic phantoms (24×24×24 mm, 32×32×32 mm, and 48×48×48 mm) and the MIRD thyroid phantom as the target regions assumed distributed uniformly for various beta-emitting radionuclides (32P, 90Y, 131I, 186Re, and 188Re) . The maximum, mean and minimum absorbed doses for their phantoms comprised of various unit voxel sizes (1×1×1 mm, 4×4×4 mm, and 8×8×8 mm) were estimated using the 3D dose matrix convolution method developed.
In the cases of the 3D cumulated radioactivity distributions of the target regions comprised of various unit voxel sizes were identical with one another, the maximum and mean absorbed doses for the target volumes were independent of the unit voxel sizes. However, as the unit voxel sizes were increased, the minimum absorbed doses were overestimated.
