:: ct scanner assessments

The ImPACT team uses test procedures which have been developed over a number of years. They are detailed in the MDA publication 'Type Testing of CT Scanners: Methods and Methodology for Assessing Imaging Performance and Dosimetry' (Report ref. MDA/98/25). The use of standardised techniques achieves results that are independent of the scanner manufacturer, and are thus comparable in a way that the use of product data sheets alone cannot achieve.

Scanning an anthropomorphic phantom at a recent assessment

ImPACT scanner assessments take three or four (long) working days to carry out, as well as pre-assessment coordination with the manufacturer. Most of the assessment time is taken up scanning various image quality and dose phantoms. Often they will take place in a hospital, but we have also visited manufacturers' sites.

Alignment of the phantoms can be a delicate business!

Large amounts of data are collected, mainly related to dose and image quality, as well as other aspects such as patient couch characteristics. The images from the scanner are transferred to our laptop or archived to CD. Many images are generated - more than 14,000 in one assessment, which are analysed using our in house, IDL based software.

Data collection

The report writing process then starts, from initial generation of noise, resolution and CTDI figures, through clinical scan tables, early report drafts, manufacturers' comments, other edits and finally publication as an evaluation report.