Radiation dose estimates in dual-source computed tomography coronary angiography (original) (raw)
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Academic Radiology, 2017
Abbreviations and Acronyms cCTA coronary computed tomography angiography ECG electrocardiographic DSCT dual-source computed tomography ROI region of interest BDP best diastolic phase BSP best systolic phase CNR contrast-to-noise-ratio DLP dose length product Rationale and Objectives: Despite ongoing technical refinements, coronary computed tomography angiography (cCTA) remains challenging in its diagnostic value by electrocardiographic (ECG) misregistration and motion artifacts, which commonly occur in patients with atrial fibrillation and high or irregular heart rates. The aim of this study was to evaluate the radiation dose and the number of inconclusive coronary segments at cCTA using retrospective ECG gating at 100 and 70 kV. Materials and Methods: With institutional review board approval, 154 patients (median age 54 years, 98 men) with high or irregular heart rate prospectively underwent retrospectively ECG-gated cCTA without tube current modulation on a third-generation dual-source computed tomography (DSCT) system at 70 kV (n = 103) or on a second-generation DSCT system at 100 kV (n = 51). Images were reconstructed in best diastolic phase (BDP), best systolic phase (BSP), and in all phases (APs) at 10% intervals across the R-R cycle. Objective and subjective image qualities were evaluated as well as the presence of motion artifacts with the three different reconstruction approaches. Results: The mean heart rate was 93 ± 16 bpm. The mean effective radiation dose was 4.5 mSv for 70 kV compared to 8.4 mSv for 100 kV (P < 0.05). At BDP reconstruction, 71% (n = 110) of the patients showed motion artifacts in one or more coronary segments. At BSP reconstruction, the number of patients with motion artifacts decreased to 37% (n = 57). In contrast, if images were reconstructed with the AP approach, all vessels and coronary segments were evaluable with both cCTA protocols. Conclusions: Retrospectively ECG-gated cCTA at 70 kV results in 52% decreased radiation dose. Further using the AP algorithm allowed for diagnostic evaluation of all coronary segments for stenosis, in contrast to BDP or BSP phase alone.
La radiologia medica, 2009
Purpose. The authors sought to compare different algorithms for dose reduction in retrospectively echocardiographically (ECG)-gated dual-source computed tomography (CT) coronary angiography (DSCT-CA) in a phantom model. Materials and methods. Weighted CT dose index (CTDI) was measured by using an anthropomorphic phantom in spiral cardiac mode (retrospective ECG gating) at five pitch values adapted with two heart-rate-adaptive ECG pulsing windows using four algorithms: narrow pulsing window, with tube current reduction to 20% (A) and 4% (B) of peak current outside the pulsing window; wide pulsing window, with tube current reduction to 20% (C) and 4% (D). Each algorithm was applied at different heart rates (45, 60, 75, 90, 120 bpm). Results. Mean CTDI volume (CTDIvol) was 36.9±9.7 mGy, 23.9±5.6 mGy, 49.7±16.2 mGy and 38.5±12.3 mGy for A, B, C and D, respectively. Consistent dose reduction was observed with protocols applying the 4% tube current reduction (B and D). Using the conversion coefficient for the chest, the mean effective dose was the highest for C (9.6 mSv) and the lowest for B (4.6 mSv). Heart-ratedependent pitch values (pitch=0.2, 0.26, 0.34, 0.43, 0.5)
European Journal of Radiology, 2010
Objective: To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120 kV setting in cardiac computed tomography angiography (CCTA). Methods: 103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100 kV group: 51 patients; 120 kV group: 52 patients). Inclusion criteria were: (1) BMI <28 kg/m 2 ; (2) weight <85 kg; (3) coronary calcium score <300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale.
Established and emerging dose reduction methods in cardiac computed tomography
Journal of Nuclear Cardiology, 2011
Cardiac computed tomography (CT) is a non-invasive modality that is commonly used as an alternative to invasive coronary angiography for the investigation of coronary artery disease. The enthusiasm for this technology has been tempered by a growing appreciation of the potential risks of malignancy associated with the use of ionising radiation. In the spirit of minimizing patient risk, the medical profession and industry have worked hard to developed methods and protocols to reduce patient radiation exposure while maintaining excellent diagnostic accuracy. A complete understanding of radiation reduction techniques will allow clinicians to reduce patient risk while providing an important diagnostic service. This review will consider the established and emerging techniques that may be adopted to reduce patient absorbed doses from x-ray CT. By modifying (1) x-ray tube output, (2) imaging time (scan duration), (3) imaging distance (scan length) and (4) the appropriate use of shielding, clinicians will be able to adhere to the 'as low as reasonably achievable (ALARA)' principle.
Seminars in Cardiovascular Medicine, 2012
The aim of the study was to estimate the decrease in ionizing radiation exposure dose using adaptive tube voltage, tube current parameters and individualized contrast media injection protocol compared to basic retrospectively ECG-gated CCTA protocol and to compare image quality. Methods: This retrospective study consisted of 30 consecutive patients who had body mass index (BMI) between 25 kg/m 2 and 30 kg/m 2 and underwent retrospectively ECG-gated CCTA. We have enrolled 15 patients which were scanned with an adaptive tube voltage, tube current and an individualized contrast media injection protocol (study group), the other 15 patients underwent basic retrospectively ECG-gated CCTA protocol (control group). Comparison of ionizing radiation effective dose, subjective and objective image quality was accomplished. Differences in ionizing radiation effective dose were deemed statistically significant if p < 0.01, for other variables we considered a p value of less than 0.05 to be statistically significant. Results: The difference of a mean effective dose between study and control groups was statistically significant (6.39 ± 0.88 mSv and 17.44 ± 2.45 mSv, p < 0.01). Despite significantly higher image noise, significantly lower contrast-to-noise ratio and signal-to-noise ratio in a study group, both groups showed comparable average image quality (62.03 ± 16.85 and 39.98 ± 8.79, p < 0.01; 5.16 ± 2.03 and 7.71 ± 1.28, p < 0.01; 3 (2.5-3) and 2.75 (2.75-3), p = 0.95). Conclusions: Despite higher image noise compared to basic retrospectively ECG-gated CCTA protocol, adaptive tube voltage, tube current parameters and individualized contrast media injection protocol allows substantial reduction in ionizing radiation exposure dose to a patient (up to 63%) with an adequate image quality for the evaluation of coronary arteries.
Actual Dose-Reduction Strategies in Cardiac Computed Tomography
Journal of Interdisciplinary Medicine, 2017
Computed tomography (CT) in cardiac examination is a powerful imaging tool that has developed rapidly during the last decade and continues to increase its potential by bringing novel technologies. Due to its noninvasive character, cardiac CT became a largely used method in detecting coronary diseases or functional issues at the expense of conventional coronary angiography. The accuracy of images has also increased, especially since new generation dual-source multi-slice detectors were developed. Although there are continuous improvements that serve to gain better-quality images, thus increasing their diagnostic accuracy, there is an inconvenient that became a serious topic for debate in the current literature: exposure to higher doses of radiation during cardiac CT examinations. Fortunately, physicians and manufacturers are taking into consideration the need to apply new strategies for radiation dose-reduction. Thus, this objective can be achieved by using patient-tailored dose-reduction strategies and by modulating the technical features of the CT scanners in order to gather highquality images with minimal radiation exposure. The aim of this manuscript was to review the current literature data on dose-reduction strategies that are used for cardiovascular computed tomography scans.
Academic Radiology, 2011
Rationale and Objectives: To investigate the effect of low-tube-voltage technique on a cardiac computed tomography (CT) for coronary arterial and cardiac functional analyses and radiation dose in slim patients. Materials and Methods: We enrolled 80 patients (52women, 28 men; mean age, 68.7 AE 8.9 years) undergoing retrospective electrocardiogram-gated 64-slice cardiac CT. Forty were subjected to the low (80-kV) and 40 to the standard (120-kV) tube-voltage protocol. Quantitative parameters of the coronary arteries (ie, CT attenuation, image noise, and the contrast-to-noise ratio [CNR]) were calculated, as were the effective radiation dose and the figure of merit (FOM). Each coronary artery segment was visually evaluated using a 5-point scale. Cardiac function calculated by using low-tube-voltage cardiac CT was compared with that on echocardiographs. Results: CT attenuation and image noise were significantly higher at 80-than 120-kV (P < .01). CNR of the left and right coronary artery was 18.4 AE 3.8 and 18.5 AE 3.3, respectively, at 80 kV; these values were 19.7 AE 2.7 and 19.8 AE 2.8 at 120 kV; the difference was not significant. The estimated effective radiation dose was significantly lower at 80 than 120 kV (6.3 AE 0.6 vs. 13.9 AE 1.1 mSv, P < .01) and FOM was significantly higher at 80 than 120 kV (P < .01). At visual assessment, 99% of the coronary segments were diagnostic quality; the two protocols did not differ significantly. We observed a strong correlation and good agreement between low-tube-voltage cardiac CT and echocardiography for cardiac functional analyses. Conclusion: Low-tube-voltage cardiac CT significantly reduced the radiation dose by approximately 55% in slim patients while maintaining anatomical image quality and accuracy of cardiac functional analysis.