Premium
Calculation of x‐ray transmission through a multileaf collimator
Author(s) -
Chen Yan,
Boyer Arthur L.,
Ma C.M.
Publication year - 2000
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.1286555
Subject(s) - multileaf collimator , monte carlo method , ray tracing (physics) , collimator , optics , beam (structure) , convolution (computer science) , fluence , physics , computational physics , computer science , linear particle accelerator , mathematics , laser , statistics , machine learning , artificial neural network
A ray tracing based method has been developed to calculate the x‐ray transmission through a multileaf collimator (MLC) for beam delivery verification and dose calculation in intensity modulated radiotherapy (IMRT). The path length of a ray line in the MLC is accurately calculated using the exact geometry of the MLC leaves. The fluence distribution of an IMRT field is calculated first using a point source. The fluence distribution for a realistic beam model is obtained, as an approximation, by convolving the point source fluence distribution with the distribution of source strength. Full ray tracing calculations are performed using analytic and Monte Carlo simulated beam models to verify the accuracy of the convolution method. The calculation is in better agreement with measurements using either film or a beam imaging system (BIS) than previous calculations for MLC transmission using a simplified model. This ray tracing calculation can be applied to the problem of verifying dynamic MLC leaf sequences as part of a patient‐specific quality assurance process for IMRT.