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• 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
Range Uncertainty
1 mm
4 mm
Reinhard W. Schulte
Loma Linda