Fig. 3.

Causes and actions for failed fractions in the second analysis: a) Causes: software problems including software bugs and irradiation on another (matched) machine with a different imager causing a deviation when comparing to a baseline of another machine; wrong imager position; problems with imager calibration; interrupted beams causing missing dose in the image; planning problems; deviations in patient position; changes in patient anatomy. b) Actions: taking a new measurement; adding extra pre-treatment imaging; plan adjustment; taking measures regarding patient preparation (e.g. bladder and rectum protocol); taking no action; adjusting the used tolerances.