Image noise-based dose adaptation in dynamic volume CT of the heart: dose and image quality optimisation in comparison with BMI-based dose adaptation.
OBJECTIVE
To compare the image quality and radiation dose using image-noise (IN)-based determination of X-ray tube settings compared with a body mass index (BMI)-based protocol during CT coronary angiography (CTCA).


METHODS
Two hundred consecutive patients referred for CTCA to our institution were divided into two groups: BMI-based, 100 patients had CTCA with the X-ray tube current adjusted to the patient's BMI while maintaining a fixed tube potential of 120 kV; IN-based, 100 patients underwent imaging with the X-ray tube current and voltage adjusted to the IN measured within the mid-left ventricle on a pre-acquisition trans-axial image. Two independent cardiac radiologists performed blinded image quality assessment with quantification of the IN and signal-to-noise ratio (SNR) from the mid-LV and qualitative assessment using a three-point score. Radiation dose (CTDI and DLP) was recorded from the console.


RESULTS
Results showed: IN (HU): BMI-based, 30.1 ± 9.9; IN-based, 33.1 ± 6.7; 32 % variation reduction (P = 0.001); SNR: BMI-based, 18.6 ± 7.1; IN-based, 15.4 ± 3.7; 48 % variation reduction (P < 0.0001). Visual scores: BMI-based, 2.3 ± 0.6; IN-based, 2.2 ± 0.5 (P = 0.54). Radiation dose: CTDI (mGy), BMI-based, 22.68 ± 8.9; IN-based, 17.16 ± 7.6; 24.3 % reduction (P < 0.001); DLP (mGy.cm), BMI-based, 309.3 ± 127.5; IN-based, 230.6 ± 105.5; 25.4 % reduction (P < 0.001).


CONCLUSIONS
Image-noise-based stratification of X-ray tube parameters for CTCA results in 32 % improvement in image quality and 25 % reduction in radiation dose compared with a BMI-based protocol.


CONCLUSIONS
• Image quality and radiation dose are closely related in CT coronary angiography. • So too are the image quality, radiation dose and body mass index (BMI). • An image-noise-based CTCA protocol reduces the radiation dose by 25 %. • It improves inter-patient image homogeneity by 32 %.
School of Medicine, Queen's University, 18 Barrie Street, Kingston, ON, K7L 3N6, Canada.
Devang
D
Odedra
Joerg
J
Blobel
Saad
S
Alhumayyd
Miranda
M
Durand
Laura
L
Jimenez-Juan
Narinder
N
Paul
D015992:Body Mass Index; D057791:Cardiac Imaging Techniques / Q000379:methods*; D054893:Cone-Beam Computed Tomography / Q000379:methods / Q000592:standards*; D017023:Coronary Angiography / Q000379:methods / Q000592:standards*; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio