Second-Generation CT Scanner Cuts Radiation Dose

Radiation exposure from coronary CT angiographies has been significantly reduced with use of a new second-generation 320-detector row CT scanner, without compromising diagnostic accuracy, according to a study published online in the journal Radiology.

A noninvasive imaging exam with a high diagnostic accuracy rate, coronary CT angiography (CCTA) is used to exclude significant coronary artery disease in ER patients who are experiencing acute chest pain. However, there have been concerns about potential cancer risk resulting from radiation exposure. In the past, lower levels of radiation often resulted in poorer quality images.

As part of a study from the National Institutes of Health, researchers performed contrast-enhanced CCTA with a second-generation 320-detector row CT system on 107 adults. The new prototype was recently approved by the FDA, and includes a gantry time of 275 milliseconds, wide volume coverage, iterative reconstruction, automated exposure control, and a larger X-ray power generator.

The researchers then compared radiation exposure and image quality to CCTA exams from 100 earlier patients that had been performed using a first-generation 320-slice scanner.

According to the results, effective radiation dose from the second-generation unit was 0.93 millisieverts (mSv) and 2.67 mSv from the first-generation unit. The median size-specific dose estimates (SSDEs) was 6.0 milligray (mGy) with the second-generation unit and 13.2 mGy with the first. Overall, the radiation dose was less than 0.5 mSv for 23 of the 107 CT angiography examinations alone (21.5 percent), less than 1 mSv for 58 (54.2 percent), and less than 4 mSv for 103 (94.3 percent). All studies were of diagnostic quality, with most having excellent image quality.

“The second-generation CT scanner provided excellent image quality over a wide range of body sizes and heart rates at low radiation doses,” said Marcus Y. Chen, MD, the study’s lead author, in a press release. “The low dose achieved during CT angiography could be used to minimize overall radiation dose to the patient or to enable additional types of imaging within reasonable radiation doses.”