Neuroradiologic applications with routine C-arm flat panel detector CT: evaluation of patient dose measurements.
OBJECTIVE
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).


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) approximately 60 mGy).


CONCLUSIONS
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.
Kyriakou
Y
Y
Institute of Medical Physics, University of Erlangen-Nuremberg, Erlangen, Germany.
Richter
G
G
Dörfler
A
A
Kalender
W A
WA
D001822:Body Burden; D005858:Germany; D006801:Humans; D009485:Neuroradiography / Q000295:instrumentation* / Q000706:statistics & numerical data*; D010361:Patients / Q000706:statistics & numerical data*; D011829:Radiation Dosage; D011874:Radiometry / Q000706:statistics & numerical data*; D012062:Relative Biological Effectiveness; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000706:statistics & numerical data*; D014963:X-Ray Intensifying Screens / Q000706:statistics & numerical data*