Markerless positional verification using template matching and triangulation of kV images acquired during irradiation for lung tumors treated in breath-hold.

Markerless positional verification using template matching and triangulation of kV images acquired during irradiation for lung tumors treated in breath-hold.
Phys Med Biol. 2018 May 01;:
Authors: Hazelaar C, Dahele M, Mostafavi H, van der Weide L, Slotman BJ, Verbakel WFAR
Abstract
Lung tumors treated in breath-hold are subject to inter- and intra-breath-hold variations, which makes tumor position monitoring during each breath-hold important. A markerless technique is desirable, but limited tumor visibility on kV images makes this challenging. We evaluated if template matching+triangulation of kV projection images acquired during breath-hold stereotactic treatments could determine 3D tumor position. Band-pass filtering and/or digital tomosynthesis (DTS) were used as image pre-filtering/enhancement techniques. On-board kV images continuously acquired during volumetric modulated arc irradiation of (i) a 3D-printed anthropomorphic thorax phantom with three lung tumors (n=6 stationary datasets, n=2 gradually moving), and (ii) 4 patients (13 datasets) were analyzed. 2D reference templates (filtered DRRs) were created from planning CT data. Normalized cross-correlation was used for 2D matching between templates and pre-filtered/enhanced kV images. For 3D verification, each registration was triangulated with multiple previous registrations. Generally applicable image processing/algorithm settings for lung tumors in breath-hold were identifi...

Source: Physics in Medicine and Biology - May 1, 2018 Category: Physics Authors: Hazelaar C, Dahele M, Mostafavi H, van der Weide L, Slotman BJ, Verbakel WFAR Tags: Phys Med Biol Source Type: research