Martin Lorenzen, Abstract Co-Author: Nothing to Disclose

Ulrike Wedegaertner MD, Presenter: Nothing to Disclose

Christoph Weber MD, PhD, Abstract Co-Author: Nothing to Disclose

Gerhard Adam, Abstract Co-Author: Nothing to Disclose

Joern Lorenzen MD, Abstract Co-Author: Nothing to Disclose

To optimize MSCT- protocols of the midface with regard to dose reduction and adequate image quality.

MSCT examinations of the midface were performed on 3 corpses with successive reduction of tube current including 150, 100, 70 and 30 mAs at 120 kV as well as 40 and 21 mAs at 80 kV. At 120 kV, a pitch of 0,875 and collimation of 4x1 mm were used. At 80 kV, a pitch of 0,7 and collimation of 2x0,5 mm were used. Images were reconstructed in transverse and coronal orientation. Qualitative image analysis was performed by two radiologists separately using a five-point scale (1= excellent; 5= poor) concerning the following parameters: Image quality, demarcation and sharpness of lamellar bone as well as overall image quality and image noise (1= minor; 5= strong). The effective dose [mSv] and organ dose [mSv] of the eye lens and the interobserver agreement (kappa-coefficient) were calculated.

Evaluation of the lamellar bone demonstrated adequate sharpness, demarcation and image quality at 120 kV/ 30 mAs. For the criteria overall image quality and noise, a dose level of 120 kV/ 40 mAs was acceptable for evaluation. With regard to image quality, the effective dose and organ dose of the eye lens could be reduced from 1,89 mSv to 0,34 mSv and 27,2 mSv to 4,8 mSv. Interobserver agreement was moderate (kappa= 0,39).

Adequate image quality for MSCT protocols of the midface was obtained at a dose level of 30 mAs at 120 kV, resulting in a dose reduction of 70 % in comparison to standard protocols.

Lorenzen, M, Wedegaertner, U, Weber, C, Adam, G, Lorenzen, J, Multislice Computed Tomography (MSCT)-Protocols of the Midface: Dose Optimization with Regard to Image Quality.  Radiological Society of North America 2005 Scientific Assembly and Annual Meeting, November 27 - December 2, 2005 ,Chicago IL. http://archive.rsna.org/2005/4417558.html