AN ASSESSMENT OF THE DOSE REDUCTION OF COMMERCIALLY AVAILABLE LEAD PROTECTIVE GLASSES FOR INTERVENTIONAL RADIOLOGY STAFF.

In light of the proposal from the International Commission on Radiological Protection for a lowered eye dose limit, now adopted by a European Union Council Directive, lead glasses may be required for some staff in interventional radiology to ensure that occupational exposure is as low as reasonably practicable. To investigate the lens protection offered from various models of lead glasses exposed to X-rays coming from a source to the left and below, calibrated radiochromic film was positioned in the lens area of a head phantom. When the source-to-eye angles were large, the dose reduction factors (the ratio of eye dose without protection to dose with protection) to the right lens area were much lower than to the left lens area, particularly with smaller-lensed glasses, due to gaps in protection between the face and the glasses. The results of this study reiterate the importance of employers providing eyewear based on the morphology of, and fit to, individual workers' faces.

Quality control within the multicentre perfusion CT study of primary colorectal cancer (PROSPeCT): results of an iodine density phantom study.

OBJECTIVES: To assess the cross-centre consistency of iodine enhancement, contrast-to-noise ratio and radiation dose in a multicentre perfusion CT trial of colorectal cancer. MATERIALS AND METHODS: A cylindrical water phantom containing different iodine inserts was examined on seven CT models in 13 hospitals. The relationship between CT number (Hounsfield units, HU) and iodine concentration (milligrams per millilitre) was established and contrast-to-noise ratios (CNRs) calculated. Radiation doses (CTDIvol, DLP) were compared across all sites. RESULTS: There was a linear relationship between CT number and iodine density. Iodine enhancement varied by a factor of at most 1.10, and image noise by at most 1.5 across the study sites. At an iodine concentration of 1 mg ml(-1) and 100 kV, CNRs ranged from 3.6 to 4.8 in the 220-mm phantom and from 1.4 to 1.9 in the 300-mm phantom. Doses varied by a factor of at most 2.4, but remained within study dose constraints. Iterative reconstruction algorithms did not alter iodine enhancement but resulted in reduced image noise by a factor of at most 2.2, allowing a potential dose decrease of at most 80% compared to filtered back projection (FBP). CONCLUSIONS: Quality control of CT performance across centres indicates that CNR values remain relatively consistent across all sites, giving acceptable image quality within the agreed dose constraints. KEY POINTS: Quality control is essential in a multicentre setting to enable CT quantification. CNRs in a body-sized phantom had the recommended value of at least 1.5. CTDIs and DLPs varied by factors of 1.8 and 2.4 respectively.