Dynamic fluence map sequencing using piecewise linear leaf position functions. (30th January 2019)

• Record Type: Journal Article
• Authors: Kelly, Matthew; van Amerongen, Jacobus H M; Balvert, Marleen; Craft, David
• Is Part Of: Biomedical physics & engineering express. Volume 5:Number 2(2019)
• Publication Date: 2019-01-30
• Subjects: MLC -- optimization -- fluence map -- sliding window; Medical physics -- Periodicals; Biophysics -- Periodicals; Biomedical engineering -- Periodicals; Medical sciences -- Periodicals; 610.153
• DOI: 10.1088/2057-1976/aaffe7
• Languages: English
• ISSNs: 2057-1976

Abstract

Abstract: Within the setting of intensity modulated radiation therapy (IMRT) and the fully continuous version of IMRT called volumetric modulated radiation therapy (VMAT), we consider the problem of matching a given fluence map as well as possible in limited time by the use of a linear accelerator (linac) with a multi-leaf collimator (MLC). We introduce two modeling strategies to manage the nonconvexity and the associated local minima of this problem. The first is the use of linear splines to model the MLC leaf positions as functions of time. The second is a progressively controllable smooth model (instead of a step function) of how the leaves block the fluence radiation. We propose a two part solution: an outer loop that optimizes the dose rate pattern over time, and an inner loop that given a dose rate pattern optimizes the leaf trajectories.