Choice strategy of different dose-saving protocols in 64-slice MDCT coronary angiography

Multidetector-row computed tomography coronary angiography (MDCT-CA) produces high-level radiation dose because of submillimetre slice thickness and short scan time. As a result, manufacturers have produced different dose-saving protocols that may, however, reduce image quality and thus diagnostic accuracy. The aim of our study was to assess the diagnostic quality of MDCT-CA using different dose-saving protocols.

Between April and August 2008, we examined 65 patients with 64-slice MDCT-CA: 6/65 using the step-and-shoot dose-saving protocol, 45/65 the cardiac dose right protocol and 14/65 using a standard protocol. Image quality was evaluated on a per-patient and per-segment basis, and the effective dose of each protocol was recorded.

In the per-patient analysis, image quality was excellent in 100% of the step-and-shoot protocols, in 91.1% of the cardiac dose right protocols and in 85.8% of the standard protocols. Effective dose to the patient considering the whole study (i.e. scout, calcium score, triggering and MDCT-CA) was 20.49 mSv in the standard protocol, 14.8 mSv in the cardiac dose right protocol and 6.63 mSv in the step-and-shoot protocol.

The radiologist should apply the appropriate protocol in relation to the clinical indications, type of patient and information required in order to spare as much dose as possible while maintaining high image quality.