Monitoring linear accelerator output constancy using the PTW Linacheck.

The PTW-Linacheck was assessed for its ability to monitor linear accelerator radiation output constancy. The key issues that were considered were the setup for daily output measurements, e.g.

An algorithm for detection of couch-beam intersection.

A graphical method of avoiding beam blocking by couch supports is described. The technique uses a simplification of the couch cross-section and matrix operations to project the beam into the plane normal to the longitudinal axis of the couch. The algorithm is described, along with a software implementation testing.