Matthew Preston Lungren MD, Presenter: Nothing to Disclose

Lynne Michelle Hurwitz MD, Abstract Co-Author: Research grant, Siemens AG

Terry T. Yoshizumi PhD, Abstract Co-Author: Research support, General Electric Company

Greta Toncheva MS, Abstract Co-Author: Nothing to Disclose

Colin Anderson-Evans BS, Abstract Co-Author: Nothing to Disclose

Xiaodong Zhou PhD, Abstract Co-Author: Employee, Siemens AG

David Scott Enterline MD, Abstract Co-Author: Consultant, Bracco Group Speakers Bureau, Bracco Group Consultant, General Electric Company Research support, Siemens AG Research support, Koninklijke Philips Electronics NV

High pitch mode of scanning on a dual source 64 MDCT has been proposed as an alternative to ECG gated protocols to eliminate cardiac motion for cardiothoracic CTA protocols. The purpose of this study was to determine the absorbed organ dose and effective dose (ED) using high pitch mode (> 1.85) of scanning for adult cardiothoracic CTA protocols.

30 MOSFET detectors (Best Medical) were placed in the thorax of a anthropopmorphic female phantom (CIRS) to measure absorbed dose. Using a dual source 64 MDCT scanner (Siemens, Definition), scan protocols were preformed three times and averaged; CTDIvol and DLP values were recorded at the time of scan. Cardiothoracic High pitch CTA protocols (dual source) were compared to standard single tube thoracic aorta and ECG gated pulmonary vein CTA protocols. Thoracic aorta high pitch (TA HP): kVp 120, qual ref mAs 270/eff mAs of 150, pitch 2.4, scan time 3.08 sec beam collimation 64 x 0.6 mm, dual tube. Pulmonary vein high pitch (PV HP): kVp 120p, qual ref mAs 352/eff mAs. 228, pitch 1.85, scan time 1.95 sec, beam collimation 64 x 0.6 mm, dual tube. Thoracic aorta standard (TA STD): kVp 120, qual ref mAs of 270/ effective mAs 141, pitch 0.8, scan time 13.39 sec, beam collimation 64 x 0.6 mm, single tube. Retrospective ECG gated current modulation pulmonary vein (PV ECG): kVp 120, mAs 430, rotation time 0.33 sec, pitch 0.26, scan time 12.9 sec beam collimation 64 x0.6 mm, single tube.

CTDIvol (mGy/cm) were 10.71, 10.18, 16.13 and 41.38 for TA HP, TA STD, PV HP and PV ECG protocols respectively. Calculated ED (mSV) were 10.16, 9.29, 11.85 and 35.56 for TA HP, TA STD, PV HP and PV ECG protocols respectively. HP PV CTA resulted in reduction of absorbed organ dose by 62-74% for the breast, lung, liver, esophagus and stomach compared to PV ECG CTA. High pitch mode of scanning for thoracic aorta CTA did not significantly change the absorbed organ doses compared to single tube mode of scanning.

High pitch mode of scanning for pulmonary vein CTA will result in a lower effective dose and lower absorbed organ doses compared to ECG gated pulmonary vein CTA. Thoracic aorta CTA high pitch will result in a similar radiation exposure compared to single tube CTA protocol.

High pitch cardiothoracic CTA protocols on a dual source scanner will have similar or reduced organ doses and effective dose while decreasing scan time.

Lungren, M, Hurwitz, L, Yoshizumi, T, Toncheva, G, Anderson-Evans, C, Zhou, X, Enterline, D, Radiation Dose Assessment for High Pitch Mode of Scanning on a Dual Source 64 MDCT Scanner.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9012321.html