According to researchers, lower peak voltage increases vascular enhancement and reduces patient radiation exposure when conducting pulmonary CT angiography.
Dr. Shin Matsuoka and team at Brigham and Women’s Hospital and Harvard Medical School in Boston reported that a voltage drop from a peak (p) of 120 kV to 100 kV significantly reduces patient radiation dose by 44% and a lower kVp setting can also improve contrast enhancement.
To provide proof for the findings, the researchers retrospectively compared results in 200 patients who underwent multidetector CT with automatic tube current modulation and a standard 120 or 130 kVp, with another 200 patients in whom a 100 or 110 kVp was employed.
The team found that low kVp group had significantly higher attenuation values of mean vascular enhancement in the main pulmonary artery compared to the standard kVp group. This was also similar for mean attenuation values in all measured segmental and subsegmental arteries.
The image noise was significantly higher in the low kVp group than in the standard group. Howeevr, there was no significant between-group difference in image quality scores.
In addition, although radiation dose was not measured, the investigators point out that given a 20 kVp drop On the basis of results of a previous study, we estimate (a) 40-50% radiation dose reduction.
Based on the results, the researchers recommend a CT protocol of 100-110 kVp for the evaluation of pulmonary embolism in clinical practice.
Dr. Matsuoka told, our findings suggest that this low kVp setting may be useful to evaluate some other vascular diseases such as aortic dissection, aortic aneurysm, and deep venous thrombus.
Actually, Dr. Matsuoka concluded, we are now evaluating the effect of low kVp setting in patients with deep venous thrombus.