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Po‐Thur Eve General‐33: Feasibility of a Multileaf Collimator and Method for Multi‐slice Tomotherapy
Author(s) -
Cadman P,
Mackie T,
Reckwerdt P
Publication year - 2006
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 - 10.1118/1.2244660
Subject(s) - tomotherapy , collimated light , multileaf collimator , collimator , optics , imaging phantom , materials science , beam (structure) , physics , nuclear medicine , linear particle accelerator , radiation therapy , laser , medicine , radiology
Purpose: Current methods for delivery of serial or helical tomotherapy are based on a collimator design which can, at most, irradiate two slices simultaneously as the source rotates around the patient. We investigate the feasibility of a novel multileaf collimator design and method for multi‐slice tomotherapy. Method and Materials: The MLC incorporates a compact pivoting leaf design. Intensity modulation is achieved through binary actuation of adjacent leaves. Multiple leaf banks are employed for multi‐slice tomotherapy delivery. Each fan beam will have a different divergence in the axial direction. Two multi‐slice delivery methods are evaluated where (a) pitch is determined by a given collimated slice which does not irradiate beyond the adjacent slice (regular pitch) or (b) pitch is determined by different collimated slices irradiating the same region in the patient (multi‐slice pitch). Junctioning effects were studied for a cylindrical phantom irradiated with open (unmodulated) fan beams. Results: A prototype MLC leaf has been tested which can switch between open and closed positions in a few tens of milliseconds. Regular pitch delivery produced the greatest inhomogeneity between regions irradiated by different collimated slices. The proposed multi‐slice pitch delivery method avoids regular pitch junctioning effects by irradiating all areas with all collimated slices. Conclusions: These results indicate that multi‐slice tomotherapy is feasible with the benefits of shorter treatment times and it may allow for the use of Co‐60 as a tomotherapy radiation source. Conflict of Interest: Research was supported in part through a licensing agreement with TomoTherapy Inc.