Marco Das MD, Presenter: Nothing to Disclose

Christian C. Hohl MD, Abstract Co-Author: Nothing to Disclose

Jan Boese, Abstract Co-Author: Employee, Siemens AG

Norbert Strobel, Abstract Co-Author: Employee, Siemens AG, Forchheim, Germany

Rosemarie Banckwitz, Abstract Co-Author: Employee, Siemens AG

Georg Mühlenbruch MD, Abstract Co-Author: Nothing to Disclose

Rolf W. Günther, Abstract Co-Author: Nothing to Disclose

Measurement of organ- and effective-doses during angiographic-CT (ACT) examinations of head, heart, liver and lumbar-spine in an anthropomorphic phantom with thermoluminiscent-dosimeters (TLD).

ACT enables cross-sectional imaging of soft-tissue structures using C-arm-fluoroscopy with flat-panel detectors (FPD). To assess organ- and effective-doses of head, heart, liver and lumbar-spine, a male Alderson-Rando-Phantom was equipped with 129 TLD in 43 different positions. The examinations were performed with two angiographic C-arm-systems (AXIOM Artis, VB31C, Siemens, Forchheim, Germany) using different size detectors: dFC (20x20cm FPD) and dFA (30x40cm). With the 20x20-detector, examinations of the head (70kV, 126 frames, 0.36µGy/frame, 7.9ms/frame), lumbar-spine (90kV, 275 frames, 0.36Gy/frame, 4.9ms/frame) and heart (70kV, 126 frames, 0.54µGy/frame, 10.9ms/frame) were performed. With the 30x40-detector examinations of liver (90kV, 397 frames, 0.36µGy/frame, 4.9ms/frame) and heart (70kV, 248 frames, 0.54µGy/frame, 4.9ms/frame) were performed. With the 30x40cm-detector an additional ecg-triggered heart-examination was performed (992 frames, 75% cardiac-phase-center, 50% cardiac-phase-width, 50% mAs-modulation). Organ- and effective-doses were calculated regarding ICRP-recommendations and compared to known dose-values of matching MSCT-scans

The effective-doses for the 20x20cm-detector amounted to 0.20mSv (head), 2.76mSv (lumbar-spine) and 1.25mSv (heart). For the 30x40cm-detector the effective-doses amounted to 6.71mSv (liver) and 3.31 mSv (heart, 248 frames). The effective-dose for the ecg-triggered heart-examination (992 frames) was 10.88mSv. Related MSCT-doses are 2.9mSv head, 4.8mSv lumbar-spine, 8.3mSv heart, and 4.3mSv liver.

Since ACT-devices have a built-in automatic exposure control, any effective patient dose depends on the patient size. Measurements involving an Alderson-Rando-Phantom showed that ACT-examinations can have lower doses than comparable MSCT-examinations.

TLD-Measurements have shown that the effective dose of ACT is roughly in the magnitude of MSCT

Das, M, Hohl, C, Boese, J, Strobel, N, Banckwitz, R, Mühlenbruch, G, Günther, R, Angiographic CT: Measurement of Patient Dose.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6021941.html