Dose 2016

Range Uncertainty

• Range accuracy is the ‘Achilles Heel’ of proton treatments • Small errors in segmentation can result in significant changes in range if they accumulate over the beam path • Accurate CT calibration curves more important in proton than photon • Few % error in CT calibration causes few % shift in range - due to the high distal gradient of the dose, this may lead to 100% difference in dose

Reinhard W. Schulte Loma Linda

1 mm

4 mm