Influence of image acquisition on radiation dose and image quality: full versus narrow phase window acquisition using 320 MDCT.
OBJECTIVE
To compare radiation dose and image quality using predefined narrow phase window versus complete phase window with dose modulation during R-R using 320-row MDCTA.


METHODS
114 patients underwent coronary CTA study using 320-row MDCT scanner. 87 patients with mean age (61 + 13 years), mean BMI (29 + 6), and mean heart rate (HR) (58 + 7 bpm) were imaged at predefined 66-80% R-R interval and then reconstructed at 75% while 27 patients with mean age (63 + 16 years), mean BMI (28 + 5), and mean HR (57 + 7 bpm) were scanned throughout the complete R-R interval with tube current modulation. The effective dose (ED) was calculated from dose length product (DLP) and conversion k (0.014 mSv/mGy/cm). Image quality was assessed using a three-point ordinal scale (1 = excellent, 2 = good, and 3 = nondiagnostic).


RESULTS
Both groups were statistically similar to each other with reference of HR (P = 0.59), BMI (P = 0.17), and tube current mAs (P = 0.68). The median radiation dose was significantly higher in those scanned with complete R-R phase window versus narrow phase window (P < 0.0001). Independently of patient and scan parameters, increased phase window was associated with higher radiation dose (P < 0.001). Image quality was better among those scanned with narrow phase window versus complete phase window (P < 0.0001).


CONCLUSIONS
Our study supports that good HR control and predefined narrow window acquisition result in lower radiation dose without compromising diagnostic image quality for coronary disease evaluation.
Department of Radiology, Emory University Hospital Midtown, Atlanta, GA, USA.
Faisal
F
Khosa
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA, USA.
Atif
A
Khan
Department of Cardiology, Yale University School of Medicine, New Haven, CT, USA.
Khurram
K
Nasir
Department of Radiology, Emory University Hospital Midtown, Atlanta, GA, USA.
Waqas
W
Shuaib
Department of Cardiology, Los Angeles Biomedical Research Institute, Torrance, CA, USA.
Matthew
M
Budoff
Department of Radiology, Brigham and Women's Hospital Harvard Medical School, Boston, MA, USA.
Ron
R
Blankstein
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard University, Boston, MA, USA.
Melvin E
ME
Clouse
D017023:Coronary Angiography / Q000379:methods*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061330:Multidetector Computed Tomography / Q000379:methods*; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity