Monte Carlo is a highly accurate method for radiotherapy in areas as diverse as treatment head design, machine calibration, and image-guided radiotherapy. For example, recent developments in precision radiotherapy require higher accuracy dose calculation to realize full clinical benefit. Monte Carlo can meet this demand. Unfortunately, Monte Carlo is extremely difficult to implement. The objective of this study is to remove this obstacle to widespread clinical use of Monte Carlo. The key requirement is an accurate, easily commissioned model of the treatment beam. Commissioning is the process of determining the parameters of the model that match the measurements peculiar to that beam. Using current methodology, a clinical physicist unfamiliar with the method would take months to commission a standard 8-beam accelerator. This is unacceptably long. The proposal is to prove beam models may be both accurate and easy to commission. This will be accomplished with 3 Specific Aims: 1. Prove Monte Carlo is sufficiently accurate for validating beam models (1%) by testing the accuracy for simulating the key accelerator components (target and scattering foils), using measurements on a research accelerator, unique in providing beams with accurate energies. 2. Combine experiment with Monte Carlo to establish detailed maps of particle fluence (particle number, energy, direction) of unprecedented accuracy (2%) for clinical beams. Detailed measurements on accelerators from the 3 major manufacturers, including source and geometry variations and beam asymmetry, will be converted to fluence maps using Monte Carlo. 3. Develop beam models with parameters extracted from routine measurements, with commissioning done in under a day per beam. Accuracy will be evaluated using the fluence maps and dose measurements. The practical result will be a pair of beam models, one for electrons, one for x-rays, which are easy to commission, meet the stringent accuracy requirement of modern radiotherapy, and apply to the bulk of radiotherapy units in clinics today. This will allow clinics around the country to take advantage of the computational accuracy of this state-of-the-art clinical tool. ? ?

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA104777-04
Application #
7429766
Study Section
Radiation Therapeutics and Biology Study Section (RTB)
Program Officer
Deye, James
Project Start
2005-07-01
Project End
2009-05-31
Budget Start
2008-06-01
Budget End
2009-05-31
Support Year
4
Fiscal Year
2008
Total Cost
$228,650
Indirect Cost
Name
University of California San Francisco
Department
Radiation-Diagnostic/Oncology
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Schreiber, Eric C; Sawkey, Daren L; Faddegon, Bruce A (2012) Sensitivity analysis of an asymmetric Monte Carlo beam model of a Siemens Primus accelerator. J Appl Clin Med Phys 13:3402
Sawkey, D; Faddegon, B A (2009) Simulation of large x-ray fields using independently measured source and geometry details. Med Phys 36:5622-32
Sawkey, D L; Faddegon, B A (2009) Determination of electron energy, spectral width, and beam divergence at the exit window for clinical megavoltage x-ray beams. Med Phys 36:698-707
Fragoso, Margarida; Kawrakow, Iwan; Faddegon, Bruce A et al. (2009) Fast, accurate photon beam accelerator modeling using BEAMnrc: a systematic investigation of efficiency enhancing methods and cross-section data. Med Phys 36:5451-66
Faddegon, Bruce A; Kawrakow, Iwan; Kubyshin, Yuri et al. (2009) The accuracy of EGSnrc, Geant4 and PENELOPE Monte Carlo systems for the simulation of electron scatter in external beam radiotherapy. Phys Med Biol 54:6151-63
Faddegon, Bruce A; Sawkey, Daren; O'Shea, Tuathan et al. (2009) Treatment head disassembly to improve the accuracy of large electron field simulation. Med Phys 36:4577-91
Faddegon, Bruce A; Asai, Makoto; Perl, Joseph et al. (2008) Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies. Med Phys 35:4308-17
Faddegon, Bruce A; Perl, Joseph; Asai, Makoto (2008) Monte Carlo simulation of large electron fields. Phys Med Biol 53:1497-510
Ross, C K; McEwen, M R; McDonald, A F et al. (2008) Measurement of multiple scattering of 13 and 20 MeV electrons by thin foils. Med Phys 35:4121-31
Li, Haisen S; Chetty, Indrin J; Solberg, Timothy D (2008) Quantifying the interplay effect in prostate IMRT delivery using a convolution-based method. Med Phys 35:1703-10

Showing the most recent 10 out of 11 publications