Optimisation of radiation dose and image quality in 3D multi-detector CT angiography in abdominal aortic aneurysm: in vitro aorta phantom study

Abstract

We aimed to investigate relationship of radiation dose and image quality in 3D multi-detector CT angiography of abdominal aortic aneurysm based on an aorta phantom. The study was conducted using a human aorta phantom modelled on a patient with an abdominal aortic aneurysm. To perform the scans of the aorta phantom it was put in a specially designed, sealable perspex container, which was filled with iodinated contrast medium. A series of scans were performed using different protocols to test the effect on dose and image quality. These were: the variable detectors (4-, 32- and 64-slice) used in image acquisition, mA and pitch values. A line profile analysis was conducted at three separate locations for each different protocol, namely, the renal artery, superior mesenteric artery, and abdominal aortic aneurysm to determine the degree of image artefacts using standard deviation, which was measured on the virtual intravascular endoscopy images. The effective dose was also calculated for each scanning protocol. Our results indicate that the scans performed on 64 detectors multi-detector CT produce better image quality compared with 32 and 4 detectors. Increasing scanning parameters such as mA enhances image quality but it increases patients? radiation dose too. It is also noted that the pitch is inversely proportional to radiation dose, resulting in degradation of image quality. From our results, a 64 multi-detector CT scanner with a scanning protocol of 120kVp, 70mA, and a pitch of 0.641 is ideal for imaging of abdominal aortic aneurysms because it allows for fewer artefacts and less radiation dose when compared to other scanning protocols.