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MO‐A‐BRB‐03: A Clinical Review of the Dosimetric and Temporal Impact of Unflattened X‐ Ray Beams
Author(s) -
Bayouth J,
Huang Y,
Flynn R,
Siochi R
Publication year - 2012
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 - 10.1118/1.4735766
Subject(s) - beam (structure) , quality assurance , medical physics , linear particle accelerator , dosimetry , nuclear medicine , laser beam quality , radiation therapy , optics , medicine , physics , radiology , laser , external quality assessment , pathology , laser beams
Since July of 2005, the University of Iowa has been using a conventional linear accelerator with the flattening filter removed. This presentation will focus on the factors affecting the dosimetric accuracy and total delivery time reduction found clinically of radiation therapy with an unfiattened beam, focusing on standard fractionation IMRT of the head and neck, as well as gated and hypo‐fractionated liver and lung cancer treatments. The dosimetric accuracy of the unfiattened beam depends on the planning system beam model, which will be briefly reviewed. The technique used to adjust the beam quality to become equivalent with a beam utilizing the flattening filter, as well as the approach to define the field size for these beams will be described. Finally, the short‐term beam stability (< 250 msec) for small MU IMRT and gated delivery will be characterized, along with the long‐term stability from the last 5‐years of clinical daily quality assurance records. Learning Objectives: 1. Understand technique for matching beam quality of unfiattened and flattened beams. 2. Understand definition of field size and beam characteristics during initial 200 msecs. 3. Review improved dosimetric accuracy and temporal advantages of unfiattened beams in clinical use.