Performing daily prostate targeting with a standard V-EPID and an automated radio-opaque marker detection algorithm

Online prostate positioning using gold markers and a standard video-based electronic portal imaging device is reported. The average systematic (random) errors have been reduced from 2.1 mm (2.7 mm) to 0.5 mm (1.5 mm) in AP direction, 1.1 mm (1.7 mm) to 0.7 mm (1.2 mm) SI and 1.2 turn (1.7 mm) to 0.6 mm (1.3 mm) LR. (C) 2004 Elsevier Ireland Ltd. All rights reserved.