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An efficient method for small field treatment dose calculation for stereotactic radiosurgery using a LINAC
Author(s) -
Lam C. F.,
Zhu J.G.
Publication year - 1998
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 - 10.1118/1.598251
Subject(s) - isocenter , collimator , radiosurgery , linear particle accelerator , cube (algebra) , dosimetry , medical imaging , radiation treatment planning , monte carlo method , truebeam , computer science , beam (structure) , medical physics , mathematics , nuclear medicine , optics , physics , artificial intelligence , imaging phantom , radiation therapy , statistics , medicine , radiology , combinatorics
The normal procedure for a physician–physicist team designing a treatment plan for multiarc stereotactic radiosurgery is the trial‐and‐error approach of changing the collimator size and the location of the isocenter of radiation and viewing the isodose curves on two‐dimensional computed tomography (CT) or magnetic resonance imaging (MRI) image planes. Automatic optimization procedures have also been used to optimize beam weight or beam size. However, either process is very time consuming. To improve the speed of the dose calculation, a random sampling method has been proposed. Unfortunately, the sampled values of an objective function are different from one sample to another. Such a sampling method cannot be used in automatic optimization because the next move in an optimization process is based on the current and past objective function values. To this end, an adaptive method based on the size of the collimators is proposed and used to determine a small volume in the shape of a hollow sphere for which the dose is calculated. With an appropriate choice of an adaptive hollow sphere, the objective function calculated based on such a hollow sphere is the same as that calculated with the traditional three‐dimensional (3‐D) cube matrix. However, with the new adaptive method, the speed of calculating a dose can be improved by a factor of 4 to a factor of 100. Because of the improvement in the speed of calculating a treatment dose, the new adaptive hollow sphere method for calculating a treatment dose can be used routinely in designing a treatment plan.