AbstractID: 8510 Title: Implementation of the Dose Planning Method (DPM) Monte
Carlo code on a parallel processing network
We have parallelized Dose Planning Method (DPM) Monte Carlo code, with the ultimate
intent of routine radiotherapy dose calculations, on an Intel cluster and AMD Linux
cluster at the University of Michigan Center for Advanced Computing. The Intel cluster
consists of 50 dual processor, 800 MHz Pentium III nodes each with 1 GB RAM and the
AMD cluster consists of 50 dual processor AMD Athlon XP 1800 MHz nodes each with
1 GB RAM. Parallelization was performed using the message passing interface (MPI)
library for interprocessor communication. Uncorrelated random number streams were
generated using the Scalable Parallel Psuedo-Random Number Generator (SPRNG)
library. The appropriate subroutine within DPM was modified to incorporate SPRNG.
Temporary buffers, assigned within DPM, are used by the master and slave processors to
store dose and error values; this significantly reduces the memory requirement for dose
calculations on individual processors. Initial evaluation shows a linear increase in
computing speed with number of processors – currently we are using up to 32 processors.
There is a noted departure from linearity in speed-up and efficiency at a larger number of
processors because of inter-processor communication and synchronization. Calculations
on the AMD cluster show that it is significantly faster than those on the Intel cluster due
to the factor of two increase in processor speed. However, increasing the number of
processors appears to reduce the efficiency on the AMD cluster faster than that on the
Intel cluster.
problem.
Optimization of the MPI broadcast calls is expected to alleviate this