Comments on 'The calibration of CT Hounsfield units for radiotherapy treatment planning'

The article by Schneider et al (1996) demonstrates the importance of using real tissue, rather than tissue substitutes, in the calibration of CT scanners for use in proton treatment planning. In order to be able to use tissue in the calibration of CT scanners, one needs a reliable scheme to calculate the Hounsfield units from the (accepted) tissue composition data. In this Letter to the Editor comments were made on the method proposed by Schneider et al (1996). Letter-to-the-editor