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Investigations on intensity‐modulated treatment techniques in conformal radiotherapy
Author(s) -
Stein Jörg
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 - 10.1118/1.598290
Subject(s) - multileaf collimator , tomotherapy , intensity modulation , computer science , dosimetry , conformal map , linear particle accelerator , optics , radiation therapy , mathematics , nuclear medicine , physics , beam (structure) , medicine , phase modulation , radiology , phase noise , mathematical analysis
The quality of treatment plans and delivery times of different intensity‐modulated treatment techniques were studied (tomotherapy, intensity‐modulated arc therapy, compensators and multileaf‐modulation). Multileaf‐modulation (MLM), i.e., the unidirectional sweep of leaves of a multileaf collimator (MLC), is the best compromise between plan quality and treatment time and is therefore developed further in this work. Several new methods to account for technical limitations of available MLCs were developed, implemented, and verified dosimetrically. These methods include: (1) a technique to describe transmission through different parts of the leaves; (2) synchronization of leaf trajectories to avoid mechanical collisions (adjacent opposing leaves are not generally allowed to pass each other) and underdosages caused by the tongue and groove design; (3) a method to correct for the finite source size and head scatter; (4) a generalized formalism to calculate leaf trajectories for dynamic and “step and shoot” type MLM. Furthermore, design requirements for MLCs were derived. In summary, MLM is the method of choice to deliver intensity‐modulated treatments, which provide dose distributions highly superior to conventional conformal treatments especially in very complex cases. The methods developed in this work allow an accurate and efficient generation of intensity‐modulated beams by MLM for large‐scale clinical applications.