Polyp measurement and size categorisation by CT colonography: effect of observer experience in a multi-centre setting.

The extent measurement error on CT colonography influences polyp categorisation according to established management guidelines is studied using twenty-eight observers of varying experience to classify polyps seen at CT colonography as either 'medium' (maximal diameter 6-9 mm) or 'large' (maximal diameter 10 mm or larger). Comparison was then made with the reference diameter obtained in each patient via colonoscopy. The Bland-Altman method was used to assess agreement between observer measurements and colonoscopy, and differences in measurement and categorisation was assessed using Kruskal-Wallis and Chi-squared test statistics respectively.

CT colonography interpretation times: effect of reader experience, fatigue, and scan findings in a multi-centre setting.

Our purpose was to assess the effect of reader experience, fatigue, and scan findings on interpretation time for CT colonography. Nine radiologists (experienced in CT colonography); nine radiologists and ten technicians (both groups trained using 50 validated examinations) read 40 cases (50% abnormal) under controlled conditions. Individual interpretation times for each case were recorded, and differences between groups determined.

Ramp test objects for slice sensitivity profile measurement in spiral CT.

Spiral CT is increasingly becoming a routine imaging technique in the UK. The ability to scan whole organs within a single breath-hold often demands that the scan pitch (ratio of the patient translation distance per tube rotation (d) to the collimated slice thickness) be increased within technically acceptable limits. It is known that the full width at half maximum height (FWHM) of the slice sensitivity profile (SSP), degrades with increasing scan pitch and also varies with interpolation algorithm.