Fig 1.
Flow chart of study population.
CCTA, coronary computed tomography angiography; APSCM, automatic tube potential selection with tube current modulation; BMI, body mass index; PCI, percutaneous coronary intervention; ECG, electrocardiography.
Table 1.
Patient characteristics and coronary CT angiography parameters.
Table 2.
Comparison of image quality between the BMI-based group and the APSCM group.
Table 3.
Comparison of radiation exposure between the BMI-based group and the APSCM group.
Fig 2.
Image quality and radiation dose according to tube potential.
(A) Image noise. (B) Contrast enhancement. (C) CNR. (D) DLP. Boxes represent the means and the first to third quartiles, mid-lines represent the medians, and whiskers indicate the minimum and maximum values. kV 1: 80 or 100 kV in the APSCM group; kV 2: 120 kV in the APSCM group; kV 3: 140 kV in the APSCM group. kV, kilovolt; APSCM, automatic tube potential selection with tube current modulation; BMI, body mass index (calculated as weight in kg/height in m2); CNR, contrast-to-noise ratio; SNR, signal-to-noise ratio; DLP, dose-length product.
Fig 3.
CT images of right coronary artery obtained in APSCM group with 100 kV and in matched BMI group.
(A) Curved multiplanar reformatted image of RCA in a 43-year-old male in the APSCM group with a BMI of 30.1 kg/m2 and heart rate of 46 beats per minute. Image was obtained in the axial mode (100 kV and 350 mAs). Mean image quality score was 4, mean contrast enhancement was 580.3 HU, mean CT number was 483.9 HU, mean image noise was 40 HU. Mean CNR and SNR were 14.5 and 12.1, respectively. CTDIvol, DLP, and effective dose were measured at 18.3 mGy, 253 mGy⋅cm, and 3.5 mSv, respectively. (B) Curved reformatted image of RCA in a 50-year-old male in the matched BMI group with a BMI of 31.6 kg/m2 and heart rate of 59 beats per minute. Image was obtained in the axial mode (120 kV and 380 mAs). Mean image quality score was 4, mean contrast enhancement was 397.1 HU, mean CT number was 324.4 HU, mean image noise was 29.1 HU. Mean CNR and SNR were 13.6 and 11.1, respectively. CTDIvol, DLP, and effective dose were measured at 27.8 mGy, 383 mGy⋅cm, and 5.4 mSv, respectively. APSCM, automatic tube potential selection with tube current modulation; BMI, body mass index; CNR, contrast-to-noise ratio; CT, computed tomography; CTDIvol, volume CT dose index; DLP, dose-length product; RCA, right coronary artery; SNR, signal-to-noise ratio.
Fig 4.
CT images in APSCM group with 120 kV and in matched BMI group.
(A) Curved multiplanar reformatted image of RCA in a 64-year-old female in the APSCM group with a BMI of 31.5 kg/m2 and heart rate of 67 beats per minute. Image was obtained in the axial mode (120 kV and 348 mAs). Mean image quality score was 3.5, mean contrast enhancement was 412.2 HU, mean CT number was 313.1 HU, mean image noise was 25.3 HU. Mean CNR and SNR were 16.3 and 12.3, respectively. CTDIvol, DLP, and effective dose were measured at 27.0 mGy, 372 mGy⋅cm, and 5.2 mSv, respectively. (B) Curved multiplanar reformatted image of RCA in a 64-year-old female in the matched BMI group with a BMI of 30.8 kg/m2 and heart rate of 68 beats per minute. Image was obtained in the axial mode (120 kV and 380 mAs). Mean image quality score was 3.75, mean contrast enhancement was 433.7 HU, mean CT number was 347.7 HU, mean image noise was 39.6 HU. Mean CNR and SNR were 11.0 and 8.8, respectively. CTDIvol, DLP, and effective dose were measured at 26.1 mGy, 366 mGy⋅cm, and 5.1 mSv, respectively. APSCM, automatic tube potential selection with tube current modulation; BMI, body mass index; CNR, contrast-to-noise ratio; CT, computed tomography; CTDIvol, volume CT dose index; DLP, dose-length product; RCA, right coronary artery; SNR, signal-to-noise ratio.
Fig 5.
CT images in APSCM group with 140 kV and in matched BMI group.
(A) Curved multiplanar reformatted image of RCA in a 56-year-old female in the APSCM group with BMI of 33.2 kg/m2 and heart rate of 73 beats per minute. Image was obtained in the axial mode (140 kV and 326 mAs). Mean image quality score was 3.25, mean contrast enhancement was 313.1 HU, mean CT number was 232.7 HU, mean image noise was 24.2 HU. Mean CNR and SNR were 12.9 and 9.6, respectively. CTDIvol, DLP, and effective dose were measured 35.3 mGy, 488 mGy⋅cm, and 6.8 mSv, respectively. (B) Curved multiplanar reformatted image of RCA in a 55-year-old female in the matched BMI group with a BMI of 33.9 kg/m2 and heart rate of 52 beats per minute. Image was obtained in the axial mode (120 kV and 450 mAs). Mean image quality score was 3.75, mean contrast enhancement was 411.0 HU, mean CT number was 322.8 HU, mean image noise was 40.4 HU. Mean CNR and SNR were 10.2 and 8.0, respectively. CTDIvol, DLP, and effective dose were measured 7.3 mGy, 135 mGy⋅cm, and 1.89 mSv, respectively. APSCM, automatic tube potential selection with tube current modulation; BMI, body mass index; CNR, contrast-to-noise ratio; CT, computed tomography; CTDIvol, volume CT dose index; DLP, dose-length product; RCA, right coronary artery; SNR, signal-to-noise ratio.
Table 4.
Subgroup analysis of image quality and radiation dose according to tube potential.
Table 5.
Predictors for selection of 140 kV.