Low-Tube-Voltage CTC Reduces Dose

May 6, 2015

Using low-tube voltage CTC provides adequate image quality at lower radiation doses.

Low-tube-voltage computed tomography colonography (CTC) reduces radiation dose but still maintains image quality, according to a study published in Academic Radiology.

Researchers from Japan sought to assess the effect of a low-tube voltage technique and iterative reconstruction (IR) on the radiation dose and image quality of CTC.

Fourteen women and 16 men (mean age 64.5) who had been diagnosed with colorectal cancer participated in the study. All underwent CTC with fecal tagging under a standard 120-kVp protocol in the supine position and a 100-kVp protocol in the prone position.

The 120-kVp images were reconstructed with filtered back projection (FBP). The 100-kVp images were postprocessed using FBP and a hybrid type of IR (adaptive iterative dose reduction 3D). The researchers compared the effective radiation dose (ED), image noise, and contrast-to-noise ratio (CNR) among the three protocols.

The results showed that the mean ED was significantly lower under the 100-kVp protocol than the 120-kVp protocol, resulting in a 27% radiation dose decrease. Image noise decreased by 48%, and the mean attenuation of tagged fluid increased from 452 to 558 HU on images acquired at 100 kVp with IR compared to that in the 120-kVp protocol; these differences were significant.

The mean CNR was significantly higher under the 100 kVp with IR than the other two protocols. We found no significant differences in the visual scores for diagnostic utility between the 100 kVp with IR and the 120 kVp with FBP protocol.

The authors concluded that the low-tube-voltage CTC reduced the radiation dose by approximately 27% while maintaining the image quality.