title: Edge detection of the radiation field in double exposure portal images using a curve propagation algorithm.
abstract: An accurate detection of the radiation field is crucial to 3D conformal radiotherapy (3D-CRT). Automated techniques to detect the field edges on double exposure portal images have previously focused on thresholding techniques. In this paper, we present a new approach based on a curve propagation technique (the Fast Marching method) which proves to be more effective at detecting the radiation field than its thresholding counterpart. The comparison of both techniques in terms of computational speed and effectiveness of the detection is presented using complex images with non-homogeneous intensity levels inside the radiation field, and gradual variations in intensity level at the field boundaries. Results show that our Fast Marching method is easier to automate, and converges faster to the boundaries of the segmented radiation field. The computation time of the Fast Marching technique is five times faster in typical portal images.
authors.affiliation: Irving K. Barber School of Arts and Sciences, University of British Columbia Okanagan, Kelowna, Canada.
authors.forename: Patricia
authors.initials: P
authors.lastname: Lasserre
authors.affiliation: Irving K. Barber School of Arts and Sciences, University of British Columbia Okanagan, Kelowna, Canada.
authors.forename: Bryce
authors.initials: B
authors.lastname: Cutt
authors.affiliation: Irving K. Barber School of Arts and Sciences, University of British Columbia Okanagan, Kelowna, Canada.
authors.forename: James
authors.initials: J
authors.lastname: Moffat
mesh_terms: D000465:Algorithms; D001331:Automation; D003201:Computers; D004867:Equipment Design; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D015233:Models, Statistical; D016011:Normal Distribution; D010315:Particle Accelerators; D010363:Pattern Recognition, Automated / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*