Dose performance of a 64-channel dual-source CT scanner.
OBJECTIVE
To prospectively compare the dose performance of a 64-channel multi-detector row computed tomographic (CT) scanner and a 64-channel dual-source CT scanner from the same manufacturer.


METHODS
To minimize dose in the cardiac (dual-source) mode, the evaluated dual-source CT system uses a cardiac beam-shaping filter, three-dimensional adaptive noise reduction, heart rate-dependent pitch, and electrocardiographically based modulation of the tube current. Weighted CT dose index per 100 mAs was measured for the head, body, and cardiac beam-shaping filters. Kerma-length product was measured in the spiral cardiac mode at four pitch values and three electrocardiographic modulation temporal windows. Noise was measured in an anthropomorphic phantom. Data were compared with data from a 64-channel multi-detector row CT scanner.


RESULTS
For the multi-detector row and dual-source CT systems, respectively, weighted CT dose index per 100 mAs was 14.2 and 12.2 mGy (head CT), 6.8 and 6.4 mGy (body CT), and 6.8 and 5.3 mGy (cardiac CT). In the spiral cardiac mode (no electrocardiographically based tube current modulation, 0.2 pitch), equivalent noise occurred at volume CT dose index values of 23.7 and 35.0 mGy (coronary artery calcium CT) and 58.9 and 61.2 mGy (coronary CT angiography) for multi-detector row CT and dual-source CT, respectively. The use of heart rate-dependent pitch values reduced volume CT dose index to 46.2 mGy (0.265 pitch), 34.0 mGy (0.36 pitch), and 26.6 mGy (0.46 pitch) compared with 61.2 mGy for 0.2 pitch. The use of electrocardiographically based tube current-modulation and temporal windows of 110, 210, and 310 msec further reduced volume CT dose index to 9.1-25.1 mGy, dependent on the heart rate.


CONCLUSIONS
For electrocardiographically gated coronary CT angiography, image noise equivalent to that of multi-detector row CT can be achieved with dual-source CT at doses comparable to or up to a factor of two lower than the doses at multi-detector row CT, depending on heart rate of the patient.
McCollough
Cynthia H
CH
CT Clinical Innovation Center, Department of Radiology, Mayo Clinic College of Medicine, 200 First St SW, Rochester, MN 55905, USA. mccollough.cynthia@mayo.edu
Primak
Andrew N
AN
Saba
Osama
O
Bruder
Herbert
H
Stierstorfer
Karl
K
Raupach
Rainer
R
Suess
Christoph
C
Schmidt
Bernhard
B
Ohnesorge
Bernd M
BM
Flohr
Thomas G
TG
D001822:Body Burden; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D011829:Radiation Dosage; D012062:Relative Biological Effectiveness; D018570:Risk Assessment; D012307:Risk Factors; D014057:Tomography, X-Ray Computed / Q000295:instrumentation*; D014915:Whole-Body Counting / Q000379:methods*