Matthias Stefan May, Presenter: Speakers Bureau, Siemens AG

Markus Lurz, Abstract Co-Author: Nothing to Disclose

Wolfgang Wust MD, Abstract Co-Author: Nothing to Disclose

Achim Eller MD, Abstract Co-Author: Nothing to Disclose

Michael Uder MD, Abstract Co-Author: Speakers Bureau, Bracco Group Speakers Bureau, Siemens AG Research Grant, Siemens AG

Michael Marcus Lell MD, Abstract Co-Author: Research Grant, Siemens AG Speakers Bureau, Siemens AG Research Grant, Bayer AG Speakers Bureau, Bayer AG Research Consultant, Bracco Group

To evaluate the potential for radiation dose reduction and increase in contrast to noise ratio by attenuation based automated tube voltage selection in a third generation dual source scanner at high pitch.

Computed Tomography (CT) of the body was performed on a dual-source system with high tube output in 43 Patients (mean BMI = 26 kg/m2). Automatically calculated tube settings (70-120 kV), based on the ap-localizer, were recorded for all 12 gradual contrast weightings to analyze the kVp distributions in 25 patients. Spiral CT was performed for all patients with an intermediate weighting (grade 7) setting in a portal venous phase at 120 ref. kv, 180 ref. mAs, 2x192x0.6mm collimation, pitch 1.55. Objective image quality was assessed as contrast to noise ratio (CNR) and subjective image quality was evaluated on a 5 point Likert scale by 2 experienced radiologists. Effective dose was calculated based on the dose length product (DLP). Previous examinations on a 64 slice scanner served as reference.

All examinations were rated good or perfect for clinical diagnosis. Automated tube voltage selection (0% at 70kV, 1% at 80kV, 21% at 90kV, 33% at 100 kV, 22% at 110kV, 23% at 120 kV) resulted in statistically significant lower radiation dose (ED = 8,0 mSv) compared to the reference (ED = 11,2 mSv, p<0.05). CNR measurements in the liver and the spleen were not statistically significant different (p>0.05) from the previous examinations while CNR was significantly increased in the aortic root and the pulmonary trunk (p<0.01). Further radiation dose reduction would have been possible by prospectively increasing the contrast weighting while tube voltage setting would have further been decreased (8% at 70kV, 20% at 80kV, 44% at 90kV, 16% at 100 kV, 0% at 110kV, 12% at 120 kV).

Automated tube voltage adaptation allows for substantial radiation dose reduction (-29%) while maintaining soft tissue contrast and increasing vessel contrast. Latest scanner generations with high tube output allow for tube voltage reduction even at large volume exposition and high pitch.

Radiation dose effectiveness is increased by latest technical x-ray tube developments and attenuation based automated tube voltage adaptation.

May, M, Lurz, M, Wust, W, Eller, A, Uder, M, Lell, M, Attenuation Based Automated Tube Voltage Selection in Computed Tomography of the Body with a Third Generation Dual Source Scanner at High Pitch.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019145.html