Individually adapted examination protocols for reduction of radiation exposure for 16-MDCT chest examinations

Abstract

Objective: The purpose of our study was to develop a simple protocol for reduction of radiation exposure without loss of diagnostic information in chest 16-MDCT.

Materials and methods: Two hundred and four patients underwent MDCT of the thorax (Somatom Sensation 16, Siemens). Group 1 was scanned using a standard protocol with 100 mAs(effective) (mAs(eff)). Group 2 was scanned using a dose modulation template (CareDose). Group 3 was scanned with mAs(eff) = body weight (kg). Group 4 was scanned with a combination of weight-adapted mAs(eff) and dose modulation. All other parameters were kept constant. Signal-to-noise ratio was assessed as an objective measurement for image quality, and subjective image quality was rated by three experienced radiologists on a 4-point scale. Effective dose was calculated using dedicated software.

Results: The mean noise measurement values were 8.31 H for the 100 mAs(eff) protocol for the regression between weight and signal-to-noise (p < 0.0001), 9.08 H for group 2 (p < 0.0001), 9.0 H for group 3 (p = 0.5051), and 9.98 H for group 4 (p = 0.0152). The median image quality was 1 (1 = highest quality) in all subgroups. The mean effective dose was 6.83 mSv, 5.92 mSv, 4.73 mSv, and 3.97 mSv, respectively. The least correlation between weight and image noise was achieved for the individually weight-adapted protocol and in the weight-adapted with CareDose combination.

Conclusion: By tube current time product adaptation (kg = mAs(eff)) combined with an online tube current modulation template, a well-balanced examination without significant loss of information was achieved for this specific scanner. Thus, individually adapted protocols for chest 16-MDCT can be recommended.