Treatment of patient-dependent beam modifiers in photon treatments by the Monte Carlo dose calculation code PEREGRINE
- Lawrence Livermore National Lab., CA (United States)
- Medical Coll. of Virginia, Richmond, VA (United States)
- Memorial Sloan-Kettering Cancer Center, New York, NY (United States)
The goal of the PEREGRINE Monte Carlo Dose Calculation Project is to deliver a Monte Carlo package that is both accurate and sufficiently fast for routine clinical use. One of the operational requirements for photon-treatment plans is a fast, accurate method of describing the photon phase-space distribution at the surface of the patient. The open-field case is computationally the most tractable; we know, a priori, for a given machine and energy, the locations and compositions of the relevant accelerator components (i.e., target, primary collimator, flattening filter, and monitor chamber). Therefore, we can precalculate and store the expected photon distributions. For any open-field treatment plan, we then evaluate these existing photon phase-space distributions at the patient`s surface, and pass the obtained photons to the dose calculation routines within PEREGRINE. We neglect any effect of the intervening air column, including attenuation of the photons and production of contaminant electrons. In principle, for treatment plans requiring jaws, blocks, and wedges, we could precalculate and store photon phase-space distributions for various combinations of field sizes and wedges. This has the disadvantage that we would have to anticipate those combinations and that subsequently PEREGRINE would not be able to treat other plans. Therefore, PEREGRINE tracks photons through the patient-dependent beam modifiers. The geometric and physics methods used to do this are described here. 4 refs., 8 figs.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 490473
- Report Number(s):
- UCRL-JC-126730; CONF-9705126-2; ON: DE97052572
- Resource Relation:
- Conference: 12. international conference on the use of computers in radiation therapy, Salt Lake City, UT (United States), 27-30 May 1997; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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