Reducing Patient Radiation Dose During Pulmonary CT Angiography

While screening for possible pulmonary emboli using pulmonary computed tomography (CT) angiography, a new study revealed that radiologists can effectively lower the patient radiation dose by approximately 44% and improve vascular enhancement without deterioration of image quality.

The study was performed by investigators from Brigham and Women's Hospital (Boston, MA, USA) and Harvard Medical School (Cambridge, MA, USA). A total of 400 patients believed to have a pulmonary embolism were assessed using pulmonary CT angiography. Two hundred patients were evaluated using the standard peak-kilovolt setting of 130 or 120 kVp and the other 200 patients were evaluated using a low peak-kilovolt setting of 110 or 100 kVp.

"Results showed that lowering the peak kilovolt setting by 20 kVp lead to superior vascular enhancement without deterioration of image quality allowing us to effectively reduce the patient radiation dose,” said Shin Matsuoka, M.D., lead author of the study. "CT has become an essential tool for the diagnosis of pulmonary embolism. However, because of the high percentage of negative results, radiation exposure has become an important issue. Our study shows that lowering the voltage setting may be an effective method of lowering the radiation dose for most patients,” he said.

"Lowering the voltage setting is something that could be easily incorporated into daily clinical practice because there is no additional equipment needed and there are no extra costs,” said Dr. Matsuoka.

The study appears in the June 2009 issue of the American Journal of Roentgenology.

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Brigham and Women's Hospital
Harvard Medical School