Assessment and improvement of the quality of radiotherapy treatment planning CT images using a clinically validated phantom based method and a multicentre intercomparison.

Purpose: To develop a phantom method of image quality assessment for radiotherapy planning CT protocols (head and neck (H&N) and prostate) and validate results against clinical image quality. Test with data from different scanners and suggest protocol adjustments.

Methods: Macros measured patient water-equivalent diameter and noise from clinical CT images.