Synthetic diamond X-ray dosimeter for radiotherapy

► Tissue Maximum Ratio values agree with those from an ion chamber to within 0.8%. ► Output Factors within 1.3% of those from an ion chamber for field sizes > 3 × 3 cm2. ► Off-Axis Ratios for face-on and edge-on orientations compared to a diode detector. ► Measured penumbral width was smallest with the detector in edge-on orientation. ► Off-Axis Ratio has been measured for a 1 × 1 cm2 field.