Meetings » 11th CTUG Meeting » Abstracts

A comparison/review of radiation doses from modern multi-sliced CTA & conventional diagnostic angiography. Techniques methods and conversion factors.

Rob Loader, Dr Oliver Gosling

Plymouth Hospitals NHS Trust


CTCA (computed tomography coronary angiography) has an established place in the non-invasive risk stratification of patients presenting with an intermediate risk of chest pain. CTCA is classed as an appropriate investigation, by the ACC/AHA guidelines, in patients with an intermediate pre-test probability of coronary artery disease who are unable to exercise/have an un-interpretable stress test.

The use of CTCA is increasing and in centres with an active programme there is a significant decrease in the number of normal invasive coronary angiograms. This emphasises the main strength of the test, its very high negative predictive value, compared to other non-invasive assessment of CAD coronary artery disease. One of the main criticisms of CTCA has been the relatively high radiation dose when compared with invasive coronary angiography. Previous studies have quoted doses of 12-14.7 mSv for CTCA; however these figures are based on obsolete scanning protocols, some of which do not incorporate modern dose reduction techniques.

Dose comparison phantoms and methods are discussed with particular attention to the measurement of nCTDIw for a partial rotation technique using prospective ECG gating on a GE VCT Computed Tomography scanner. The effects of partial rotation on the estimation of organ doses are also discussed with particular attention to the Breasts.

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