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AJNR - American Journal of Neuroradiology

Published ahead of print on August 7, 2008
doi: 10.3174/ajnr.A1237

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American Journal of Neuroradiology 29:1930-1936, November-December 2008
© 2008 American Society of Neuroradiology

INTERVENTIONAL

Neuroradiologic Applications with Routine C-arm Flat Panel Detector CT: Evaluation of Patient Dose Measurements

Y. Kyriakou^a, G. Richter^b, A. Dörfler^b and W.A. Kalender^a

^a Institute of Medical Physics, University of Erlangen-Nuremberg, Erlangen, Germany
^b Department of Neuroradiology, University of Erlangen-Nuremberg, Erlangen, Germany

Please address correspondence to Dr. Yiannis Kyriakou, Institute of Medical Physics, University of Erlangen-Nuremberg, Henkestr 91, 91052 Erlangen, Germany; e-mail: yiannis.kyriakou{at}imp.uni-erlangen.de

BACKGROUND AND PURPOSE: Since the introduction of flat panel detector–equipped C-arms, the use of flat panel detector CT (FPCT) in the neuroradiologic angiography suite has become more frequent. This examination implicates its own specific radiation exposure. We used the CT dose index (CTDI) concept and adapted it to the special FPCT geometry to provide a consistent comparison with multisection head CT (cCT).

MATERIALS AND METHODS: Exposure data obtained for routine scanning during a period of 1 year were used to assess a specific dose of a total of 217 rotational scans performed in 105 patients. One hundred seventy-two scans were 3D digital subtraction angiography (DSA) scans. There were 45 scans that were performed to achieve high-quality, soft-tissue resolution. Dose measurements in cylindrical polymethylmethacrylate (PMMA) phantoms were used to determine the CTDI value and to compare it with the reference values for cCT. In addition, the dose-area product (DAP) was registered and correlated with the CTDI and corresponding dose-length product (DLP) values. Exposure data and dose values were compared with cCT.

RESULTS: Mean-weighted CTDI value of 3D-DSA was approximately 9 mGy per scan. High-quality, soft-tissue resolution FPCT scans, comparable with cCT, revealed a mean dose value of 75 mGy (reference value for cCT, CTDI_w 60 mGy).

CONCLUSION: The high-speed scans used for 3D-DSA revealed a significantly lower CTDI_w and DLP compared with clinical CT. The high-quality FPCT protocol resulted in a higher dose and should therefore be limited to acute cases, when patient transfer to a CT scanner is considered to be a disadvantage for patient management.