A seed specific dose kernel method for low-energy brachytherapy dosimetry.
We describe a method for independently verifying the dose distributions from pre- and post-implant brachytherapy source distributions. Monte Carlo calculations have been performed to characterize the three-dimensional dose distribution in water phantom from a low-energy brachytherapy source. The calculations are performed in a voxelized, Cartesian coordinate geometry and normalized based upon a separate Monte Carlo calculation for the seed specific air-kerma strength to produce an absolute dose grid with units of cGy hr(-1) x U(-1). The seed-specific, three-dimensional dose grid is stored as a text file for processing using a separate visual basic program. This program requires the coordinate positions of each seed in the pre- or post-plan and sums the kernel file for a three-dimensional composite dose distribution. A kernel matrix size of 81x81x81 with a voxel size of 1.0x1.0x1.0 mm3 was chosen as a compromise between calculation time, kernel size, and truncation of the stored dose distribution as a function of radial distance from the midpoint of the seed. Good agreement is achieved for a representative pre- and post-plan comparison versus a commercial implementation of the TG-43 brachytherapy dosimetry protocol.
DeMarco
John J
JJ
Department of Radiation Oncology, UCLA School of Medicine, Los Angeles, California 90095, USA. demarco@randoc.ucla.edu
Solberg
Timothy D
TD
Agazaryan
Nzhde
N
D000465:Algorithms; D001918:Brachytherapy / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000737:chemistry; D008297:Male; D009010:Monte Carlo Method; D011467:Prostate / Q000528:radiation effects; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*
D007457:Iodine Radioisotopes