NEW YORK (Reuters Health) — At the University of California, San Francisco, systematic use of tube current dose modulation for computed tomography (CT) examinations most often performed in the neuroradiology section has led to significant reductions in radiation doses without sacrificing image quality.

Dr. Alice B. Smith and colleagues report their observation in the May issue of the journal Radiology. They evaluated the effect of dose modulation on adult and pediatric brain CT scans performed without contrast material (unenhanced), adult cervical spine CT, and adult cervical and intracranial CT angiography.

For each type of CT study, the clinicians reviewed three series of 100 consecutive studies: 100 studies performed without dose modulation; 100 studies performed with z-axis dose modulation (both used with the 16-section CT scanner); and 100 performed with x-y-z-axis dose modulation (used with the 64-section CT scanner).

Dr. Smith and colleagues found that the use of dose modulation techniques resulted in significant reductions of up to 60.9% (p < 0.001) in radiation dose to adults and children.

Image quality and noise were unaffected by the use of either z-axis or x-y-z-axis dose modulation (p > 0.05), they also report.

Based on their experience, Dr. Smith and colleagues "recommend routine use of dose modulation for neuroradiology CT examinations because this approach affords a significant dose reduction while preserving image quality."

"Implementation of dose modulation," they note, "requires a fine-tuning process to identify optimal signal-to-noise level for each type of CT study performed."

Radiology 2008;247:499-506.

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