Radiation dose for 320‐row dose‐modulated dynamic coronary CT angiography

Abstract

Objectives The area detector 320‐row CT scanner, which can cover the whole heart in one rotation, can aid in reducing radiation exposure during electrocardiography (ECG)‐gated coronary CT angiography (CCTA). Recently, researchers have proposed dose‐modulated dynamic CCTA with a 320‐row scanner for the detection of functional myocardial ischemia. In the present study, we compared and validated the radiation dose of this method with that of the standard CCTA method and the latest diagnostic reference levels (DRLs). Materials and Methods The study included a total of 164 consecutive patients with suspected or known coronary artery disease (CAD) who underwent CCTA with a 320‐row scanner. The patients were randomly divided into dynamic and standard CCTA groups, and the CT dose index (CTDIvol) and dose length product (DLP) calculated by the CT system were compared between the two protocols and with the latest DRL. Results Standard and dynamic CCTA scans were performed in 77 and 87 patients, respectively. CTDIvol was significantly higher for standard CCTA than for dynamic CCTA (41 ± 35 mGy vs. 22 ± 7 mGy, p = 0.0014). DLP was also significantly higher for standard CCTA than for dynamic CCTA (864 ± 702 mGy × cm vs. 434 ± 106 mGy × cm, p < .0001). For standard scans, CTDIvol and DLP exceeded the 2020 DRL in Japan in 16% (12/77) and 17% (13/77) of cases, respectively. In contrast, rates for the dynamic scan were only 1% (1/87) for CTDIvol and 0% (0/87) for DLP. Conclusion The dose of radiation exposure during dynamic CCTA with a 320‐row scanner does not exceed that of standard CCTA and is sufficient to meet the latest DRL. Thus, our results suggest that the method is safe from the perspective of radiation exposure.

Dynamic coronary CT Angiography-Estimated coronary flow in Non-Obstructive, Plaque-free coronary Arteries: Association with dyslipidemia and diabetes

“…It has recently been reported that dynamic CCTA scanning can estimate functional myocardial ischemia [35] and can also estimate myocardial blood flow via ammonia PET [1] . The scan protocol used in this study, which combines standard CCTA with low-dose dynamic imaging using a 320-row scanner, does not increase radiation exposure as compared to conventional CCTA [23] .…”

“…One scan of the dynamic CCTA was performed as a boost scan for standard CCTA at the peak phase of the ascending aorta. The scan parameters were as follows: gantry rotation time, 0.275 s; detector collimation, 320 × 0.5 mm; tube voltage, 100 kV; tube current, 80 mA at the dynamic scan, and auto radiation exposure reducing control at the boost scan with a field of view of 200 mm [23] .…”

Recent technologies in cardiac imaging

“…Ordinary CT scans take 1 to 10 s per slice, but recent CT scanners have many rows of detectors, some up as high as 320 rows, that can take multiple x-rays of the heart simultaneously ( 96 ). This type of technology is called multidetector computed tomography (MDCT), and MDCT is considered the new gold standard for preoperative planning ( 97 ).…”

Head CT dose reduction with organ‐based tube current modulation

“…Head CT requires high contrast resolution with low image noise. When helical CT is used, the pitch factor (PF) is set to <1.0 and the tube current is set to high, with a resulting radiation dose that is higher than that to chest, abdomen, and other imaging sites imaged with a lower PF 9–14 . When the PF is <1.0, some areas are irradiated twice, increasing the dose.…”

“…the pitch factor (PF) is set to <1.0 and the tube current is set to high, with a resulting radiation dose that is higher than that to chest, abdomen, and other imaging sites imaged with a lower PF. [9][10][11][12][13][14] When the PF is <1.0, some areas are irradiated twice, increasing the dose. The lens is often directly irradiated twice.…”