Breast Surface Radiation Dose During Coronary CT Angiography: Reduction by Breast Displacement and Lead Shielding (original) (raw)
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Coronary CT angiography: current status and continuing challenges
British Journal of Radiology, 2012
Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted.
PloS one, 2016
This study aimed to measure the absorbed doses in selected organs for prospectively ECG-triggered coronary computed tomography angiography (CCTA) using five different generations CT scanners in a female adult anthropomorphic phantom and to estimate the effective dose (HE). Prospectively ECG-triggered CCTA was performed using five commercially available CT scanners: 64-detector-row single source CT (SSCT), 2 × 32-detector-row-dual source CT (DSCT), 2 × 64-detector-row DSCT and 320-detector-row SSCT scanners. Absorbed doses were measured in 34 organs using pre-calibrated optically stimulated luminescence dosimeters (OSLDs) placed inside a standard female adult anthropomorphic phantom. HE was calculated from the measured organ doses and compared to the HE derived from the air kerma-length product (PKL) using the conversion coefficient of 0.014 mSv∙mGy-1∙cm-1 for the chest region. Both breasts and lungs received the highest radiation dose during CCTA examination. The highest HE was rece...
Heart, Lung and Circulation, 2011
New technologies for computed tomography coronary arteries imaging aim to reduce the radiation dose whilst maintaining image quality. The purpose of our study was to compare radiation dose and image quality parameters of Coronary Computed Tomography Angiography (CCTA) performed with retrospective 64-MDCT and prospective 128-MDCT. Patients and Methods: A series of 77 consecutive patients were first randomised to either retrospective 64-MDCT (n = 37) or prospective 128-MDCT (n = 40) for CCTA. All patients in the retrospective 64-MDCT group were scanned with tube current modulation as strategy for reduction dose. Data regarding acquisition time and radiation dose were recorded. Two blinded radiologists independently assessed image quality of all coronary segments by using a four-point scale (1, excellent; 4, poor). Discrepancies were settled by consensus. Results: No significant differences were found regarding sex, age, body weight and heart rate. CTTA effective radiation dose was 2.1 ± 0.9 vs. 8.2 ± 4 mSv in prospective and retrospective ECG-gating MDCT groups, respectively. Mean image quality score was 2.2 ± 0.9 for prospective 128-MDCT group and 1.4 ± 0.7 points for retrospective 64-MDCT representing a mean difference of 0.8 points (CI: 0.9 to 0.7). Conclusion: In selected patients, CCTA using a 128-MDCT with prospective ECG-gating provides higher image quality with significant lower radiation dose when compared to 64-MDCT using retrospective ECG-gating.
Radiation Protection Dosimetry, 2011
This study was conducted on a human anthropomorphic phantom to investigate the effective dose and entrance skin dose in selected radiosensitive organs through invasive and CT coronary angiography procedures using different dose-saving techniques. The effective dose was calculated as 2.49 mSv, 3.35 mSv, and 9.62 mSv respectively, corresponding to three coronary CT angiography protocols including, prospective ECG-gating, retrospective ECGgating with and without tube current modulation. In comparison, effective dose was calculated as 7.26 mSv, 6.35 mSv, 5.58 mSv, and 4.71 mSv at four different magnifications acquired with invasive coronary angiography. The highest entrance skin dose was measured at the breast during the coronary CT angiography and at the thyroid gland during invasive coronary angiography. Although invasive coronary angiography produces lower radiation dose than coronary CT angiography, application of modified techniques in both CT and invasive coronary angiography is recommended in clinical practice for radiation dose reduction.
Multidetector Computed Tomography (MDCT) is now an established modality for noninvasive cardiac imaging. Until recently, 64-slice CT provided state-of-the-art noninvasive coronary imaging. The 64 slices per gantry rotation can be achieved with either 64-detector rows, or 32-detector rows and a strategy to double the slice number by alternating the focal spot of the x-ray source. These " 64-generation " scanners offered considerable advantages over earlier technology: superior spatial resolution, temporal resolution, volume coverage, and lower radiation doses for patients. Improving upon these fundamental CT parameters is also the goal of the next generation, or " post-64 " era of coronary CT angiography (CTA). This review highlights improvements in the post-64 era of cardiac MDCT. The newest technology offers significant advantages, but unlike the evolution from 4-to 64-detector row coronary CTA, current CT hardware releases are far from uniform, reflecting different approaches to image acquisition in the post-64 era. No single CT scanner offers the full portfolio of the newest features. This situation underscores the importance of understanding the properties of a cardiac CT scanner. Also, CT vendors continue to eclipse the state-of-the-art from even the recent past. Thus, it is very challenging to accumulate " current " clinical evidence. This reality is reflected in two multi-center 64-era MDCT trials, each of which focused on a single CT platform. The first of these publications,1 the Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography (ACCURACY) trial, enrolled United States subjects from predominantly nonacademic (private) centers and found a (patient based) sensitivity, specificity, and positive and negative predictive values to detect >50% or >70% stenosis of 0.95, 0.83, 0.64, and 0.99, respectively, and 0.94, 0.83, 0.48, 0.99, respectively. The second publication, 2 the Coronary Artery Evaluation Using 64-Row Multidetector Computed Tomography Angiography (Core64) study was both international and included predominantly academic centers. This trial had lower test characteristics (patient based detection of >50% stenosis, sensitivity, specificity, and positive and negative predictive of 0.85, 0.90, 0.91, 0.83) but showed a similar ability of CT when compared to catheterization to identify, on the basis of obstructive coronary stenoses, patients who underwent revascularization.
Clinical Radiology, 2010
To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded. There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square=15.331, p=0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71+/-0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p<0.001). Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.
Journal of Medical Imaging and Radiation Oncology, 2012
The purpose of this paper is to perform a systematic review on radiation dose reduction in coronary computed tomography (CT) angiography that is done using different generations of multidetector CT (MDCT) scanners ranging from four-slice to 320-slice CTs, and have different dose-saving techniques. The method followed was to search for references on coronary CT angiography (CTA) that had been published in English between 1998 and February 2011. The effective radiation dose reported in each study based on different generations of MDCT scanners was analysed and compared between the types of scanners, gender, exposure factors and scanning protocols. Sixty-six studies were eligible for inclusion in this analysis. The mean effective dose (ED) for MDCT angiography with retrospective electrocardiogram (ECG) gating without use of any dose-saving protocol was 6.0 Ϯ 2.8, 10.4 Ϯ 4.90 and 11.8 Ϯ 5.9 mSv for four-slice, 16-slice and 64-slice CTs, respectively. More dosesaving strategies were applied in recent CT generations including prospective ECG-gating protocols, application of lower tube voltage and tube current modulation to achieve a noteworthy dose reduction. Prospective ECGgating protocol was increasingly used in 64, 125, 256 and 320 slices with corresponding ED of 4.1 Ϯ 1.7, 3.6 Ϯ 0.4, 3.0 Ϯ 1.9 and 7.6 Ϯ 1.6 mSv, respectively. Lower tube voltage and tube current modulation were widely applied in 64-slice CT and resulted in significant dose reduction (P < 0.05). This analysis has shown that dose-saving strategies can substantially reduce the radiation dose in CT coronary angiography. The fact that more and more clinicians are opting for dose-saving strategies in CT coronary angiography indicates an increased awareness of risks associated with high radiation doses among them.
Radiation Protection Dosimetry, 2013
A retrospective analysis was performed in patients undergoing prospective ECG-triggered coronary computed tomography (CT) angiography (CCTA) with the single-source 64-slice CT (SSCT), dual-source 64-slice CT (DSCT), dual-source 128slice CT and 320-slice CT with the aim of comparing the radiation dose associated with different CT generations. A total of 164 patients undergoing prospective ECG-triggered CCTA with different types of CT scanners were studied with the mean effective doses estimated at 6.8+ + + + +3.2, 4.2+ + + + +1.9, 4.1+ + + + +0.6 and 3.8+ + + + +1.4 mSv corresponding to the 128-slice DSCT, 64-slice DSCT, 64-slice SSCT and 320-slice CT scanners. In this study a positive relationship was found between the effective dose and the body mass index (BMI). A low radiation dose is achieved in prospective ECG-triggered CCTA, regardless of the CT scanner generation. BMI is identified as the major factor that has a direct impact on the effective dose associated with prospective ECG-triggered CCTA.
The “Post-64” Era of Coronary CT Angiography: Understanding New Technology from Physical Principles
Radiologic Clinics of North America, 2009
Multidetector Computed Tomography (MDCT) is now an established modality for noninvasive cardiac imaging. Until recently, 64-slice CT provided state-of-the-art noninvasive coronary imaging. The 64 slices per gantry rotation can be achieved with either 64-detector rows, or 32detector rows and a strategy to double the slice number by alternating the focal spot of the xray source. These "64-generation" scanners offered considerable advantages over earlier technology: superior spatial resolution, temporal resolution, volume coverage, and lower radiation doses for patients. Improving upon these fundamental CT parameters is also the goal of the next generation, or "post-64" era of coronary CT angiography (CTA). This review highlights improvements in the post-64 era of cardiac MDCT.