Quality control of CT system for treatment planning using the polybinary calibration method.

A guideline for quality assurance of CT systems for radiotherapy treatment planning is proposed. Quantitative interpretation of CT number is very important especially for range calculation in heavy charged particle radiotherapy, for which we adopted the polybinary calibration method to correct variations among CT systems and scanning conditions. Practical procedures for commissioning and constancy testing are documented along with the methodologies against various sources of uncertainty. We propose this guideline for quality assurance of heavy charged particle radiotherapy.