Influence of Image Acquisition on Radiation Dose and Image Quality: Full versus Narrow Phase Window Acquisition Using 320 MDCT

Purpose. 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). Conclusion:. 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

Radiation exposure for coronary artery calcium score at prospective 320 row multi-detector computed tomography

Purpose:To date there is extensive data on the radiation dose for assessing coronary artery calcium scores (CACS) with 4-64 row multidetector MDCT. However with the advent of 320 row MDCT, the entire heart can be imaged in one beat and thus potentially reduce the radiation dose. The aim of this study was to evaluate radiation dose for CACS on low-dose prospective EKG-triggered 320 row MDCT.Materials and Methods: Informed consent for this retrospective HIPAA-compliant study was waived and approved by our institution’s institutional review board IRB. One hundred and sixty eight consecutive patients (Male 133 (79%): female 35 (21%), mean body mass index BMI 29±5 and mean heart rate 58± bpm) underwent coronary calcium scoring with prospective gating. The scan parameters were 300 mA, 120 kVp, volume scan length (VSL) 160 mm, gantry rotation 0.350 msec and 320 x 0.5 mm detectors at 320 MDCT. Beta blockers were given to patients in a case heart rate HR &gt; 65 bpm. The effective dose (ED) estimates were calculated for all patients from the dose length product and the conversion factor k (0.014 mSv/mGy/cm) as recommended by current guidelines.Results: The mean SD radiation was 1.89±0.79 mSv. Overall the range varied from 0.28-2.48 mSv. The radiation was significantly less in females as compared to males (2.02±0.73 vs. 1.41±0.87, p&lt;0.0001). No differences were noted whether HR was &lt;60 vs. &gt;=60 bpm (1.87±0.79 vs. 1.77±0.84 mSv, p=0.45). On the other hand a higher radiation was noted among obese individuals as compared to those with BMI&lt;30 (1.84±0.82 vs. 1.91±0.80 mSv, p=0.62).Conclusion: Radiation dose obtained from 320-MDCT is similar to those obtained with 4-64 row MDCT. Further studies are needed to assess the feasibility of further lowering the tube current and tube voltage.------------------------------------------------Cite this article as:Khosa F, Khan A, Shuaib W, Clouse M, Budoff M, Blankstein R, Nasir K. Radiation exposure for coronary artery calcium score at prospective 320 row multi-detector computed tomography. Int J Cancer Ther Oncol 2013; 1(2):01023.DOI: http://dx.doi.org/10.14319/ijcto.0102.

Radiation exposure for coronary artery calcium score at prospective 320 row multi-detector computed tomography

Purpose:To date there is extensive data on the radiation dose for assessing coronary artery calcium scores (CACS) with 4-64 row multidetector MDCT. However with the advent of 320 row MDCT, the entire heart can be imaged in one beat and thus potentially reduce the radiation dose. The aim of this study was to evaluate radiation dose for CACS on low-dose prospective EKG-triggered 320 row MDCT.Materials and Methods: Informed consent for this retrospective HIPAA-compliant study was waived and approved by our institution’s institutional review board IRB. One hundred and sixty eight consecutive patients (Male 133 (79%): female 35 (21%), mean body mass index BMI 29±5 and mean heart rate 58± bpm) underwent coronary calcium scoring with prospective gating. The scan parameters were 300 mA, 120 kVp, volume scan length (VSL) 160 mm, gantry rotation 0.350 msec and 320 x 0.5 mm detectors at 320 MDCT. Beta blockers were given to patients in a case heart rate HR &gt; 65 bpm. The effective dose (ED) estimates were calculated for all patients from the dose length product and the conversion factor k (0.014 mSv/mGy/cm) as recommended by current guidelines.Results: The mean SD radiation was 1.89±0.79 mSv. Overall the range varied from 0.28-2.48 mSv. The radiation was significantly less in females as compared to males (2.02±0.73 vs. 1.41±0.87, p&lt;0.0001). No differences were noted whether HR was &lt;60 vs. &gt;=60 bpm (1.87±0.79 vs. 1.77±0.84 mSv, p=0.45). On the other hand a higher radiation was noted among obese individuals as compared to those with BMI&lt;30 (1.84±0.82 vs. 1.91±0.80 mSv, p=0.62).Conclusion: Radiation dose obtained from 320-MDCT is similar to those obtained with 4-64 row MDCT. Further studies are needed to assess the feasibility of further lowering the tube current and tube voltage.------------------------------------------------Cite this article as:Khosa F, Khan A, Shuaib W, Clouse M, Budoff M, Blankstein R, Nasir K. Radiation exposure for coronary artery calcium score at prospective 320 row multi-detector computed tomography. Int J Cancer Ther Oncol 2013; 1(2):01023.DOI: http://dx.doi.org/10.14319/ijcto.0102.3</p