AbstractID: 8254 Title: Towards Sub-Minute Monte Carlo Based Dosimetry
Current brachytherapy dose calculations ignore applicator attenuation and tissue
heterogeneities. . Monte Carlo photon transport (MCPT) simulations can accurately
estimate absorbed dose in the presence of such heterogeneities, but until now have been
too slow and time-intensive for clinical treatment planning. To address this problem, we
have adapted our MCPT code: PTRAN (Med. Phys. 15: 686) for parallel execution on a
cluster of 24 PC computers. Each node is equipped with an AMD “Thunderbird” CPU,
running at 1.53 GHz with 512 Mb of DDRAM. Nodes are interconnected with gigabit
network interface cards and the appropriate network switch. Efficiency was further
increased by employing a generalized correlated sampling algorithm(PMB 47: 351).
Specifically, the efficiency of correlated sampling PTRAN running on 20 nodes was
increased 140-fold compared to conventional PTRAN running on a single processor. For
a clinical intracavitary implant (tandem and shielded colpostats with 50 geometric
components), the median standard error of the mean was 1% for a 15 minute runtime for
a 1003 of 1.8x1.8x2.8 mm3 voxels.
This work was supported by grants R01 CA 46640, CA 85181, and CA 84409 awarded
by NIH.