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Leaf position verification during dynamic beam delivery: A comparison of three applications using electronic portal imaging
Author(s) -
Partridge Mike,
Evans Philip M.,
van Herk Marcel,
Ploeger Lennert S.,
Budgell Geoffrey J.,
James Hayley V.
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 - 10.1118/1.599026
Subject(s) - multileaf collimator , collimator , computer science , beam (structure) , linear particle accelerator , medical imaging , dosimetry , medical physics , optics , nuclear medicine , physics , artificial intelligence , medicine
The use of a dynamic multileaf collimator (MLC) to deliver intensity‐modulated beams presents a problem for conventional verification techniques. The use of electronic portal imaging to track MLC leaves during beam delivery has been shown to provide a solution to this problem. An experimental comparison of three different verification systems, each using a different electronic portal imaging technology, is presented. Two of the systems presented are commercially available imagers with in‐house modifications, with the third system being an in‐house built experimental system. The random and systematic errors present in each of the verifications systems are measured and presented, together with the study of the effects of varying dose rate and leaf speed on verification system performance. The performance of the three systems is demonstrated to be very similar, with an overall accuracy in comparing measured and prescribed collimator trajectories of approximately ± 1.0 mm . Systematic errors in the percentage delivered dose signal provided by the accelerator are significant and must be corrected for good performance of the current systems. It is demonstrated that, with suitable modifications, commercially available portal imaging systems can be used to verify dynamic MLC beam delivery.