Premium
Portal dose image (PDI) prediction for dosimetric treatment verification in radiotherapy. I. An algorithm for open beams
Author(s) -
Pasma K. L.,
Heijmen B. J. M.,
Kroonwijk M.,
Visser A. 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 - 10.1118/1.598293
Subject(s) - dosimetry , radiation treatment planning , focus (optics) , beam (structure) , medical imaging , nuclear medicine , detector , image quality , transmission (telecommunications) , linear particle accelerator , photon , physics , radiation therapy , computer science , optics , medical physics , image (mathematics) , medicine , radiology , computer vision , artificial intelligence , telecommunications
A method is presented for calculation of transmission functions for high energy photon beams through patients. These functions are being used in our clinic for prediction of portal dose images (PDIs) which are compared with PDIs measured with an electronic portal imaging device (EPID). The calculations are based on the planning CT‐scan of the patient and on the irradiation geometry as determined in the treatment planning process. For each beam quality, the required input data for the algorithm for transmission prediction are derived from a limited number of measured beam data. The method has been tested for a PDI‐plane at 160 cm from the focus, in agreement with the fixed focus‐to‐detector distance of our fluoroscopic EPIDs. For 6, 23 and 25 MV photon beams good agreement (∼1%) has been found between calculated and measured transmissions through anthropomorphic phantoms.