A practical Monte Carlo MU verification tool for IMRT quality assurance
- 26 April 2006
- journal article
- research article
- Published by IOP Publishing in Physics in Medicine & Biology
- Vol. 51 (10), 2503-2515
- https://doi.org/10.1088/0031-9155/51/10/010
Abstract
Quality assurance (QA) for intensity-modulated radiation therapy (IMRT) treatment planning and beam delivery, using ionization chamber measurements and film dosimetry in a phantom, is time consuming. The Monte Carlo method is the most accurate method for radiotherapy dose calculation. However, a major drawback of Monte Carlo dose calculation as currently implemented is its slow speed. The goal of this work is to bring the efficiency of Monte Carlo into a practical range by developing a fast Monte Carlo monitor unit (MU) verification tool for IMRT. A special estimator for dose at a point called the point detector has been used in this research. The point detector uses the next event estimation (NEE) method to calculate the photon energy fluence at a point of interest and then converts it to collision kerma by the mass energy absorption coefficient assuming the presence of transient charged particle equilibrium. The MU verification tool has been validated by comparing the calculation results with measurements. It can be used for both patient dose verification and phantom QA calculation. The dynamic leaf-sequence log file is used to rebuild the actual MLC leaf sequence in order to predict the dose actually received by the patient. Dose calculations for 20 patient plans have been performed using the point detector method. Results were compared with direct Monte Carlo simulations using EGS4/MCSIM, which is a well-benchmarked Monte Carlo code. The results between the point detector and MCSIM agreed to within 2%. A factor of 20 speedup can be achieved with the point detector method compared with direct Monte Carlo simulations.Keywords
This publication has 28 references indexed in Scilit:
- Guidance document on delivery, treatment planning, and clinical implementation of IMRT: Report of the IMRT subcommittee of the AAPM radiation therapy committeeMedical Physics, 2003
- Independent monitor unit calculation for intensity modulated radiotherapy using the MIMiC multileaf collimatorMedical Physics, 2002
- A monitor unit verification calculation in intensity modulated radiotherapy as a dosimetry quality assuranceMedical Physics, 2000
- The impact of electron transport on the accuracy of computed doseMedical Physics, 2000
- Monte Carlo calculations of electron beam output factors for a medical linear acceleratorPhysics in Medicine & Biology, 1998
- Clinical considerations of Monte Carlo for electron radiotherapy treatment planningRadiation Physics and Chemistry, 1998
- A CT‐based Monte Carlo simulation tool for dosimetry planning and analysisMedical Physics, 1998
- Monte Carlo techniques in medical radiation physicsPhysics in Medicine & Biology, 1991
- Electron dose distributions in experimental phantoms: a comparison with 2D pencil beam calculationsPhysics in Medicine & Biology, 1987
- On the Estimation of Flux at a Point by Monte CarloNuclear Science and Engineering, 1963