Congress:
EuroSafe Imaging 2016
Keywords:
Action 4 - Quality of radiological equipment, Action 3 - Optimisation, diagnostic reference levels, image quality, Action 2 - Clinical audit, Action 6 - Clinical audit tool for imaging, Action 2 - Clinical diagnostic reference levels (DRLs), Action 3 - Image quality assessment based on clinical indications
Authors:
E. J. R. Van Beek, M. Williams, M. Rodriguez, A. Marin, N. Weir, S. Mirsadraee, D. E. Newby
DOI:
10.1594/esi2016/ESI-0005
Background/Introduction
Radiation dose is an important concern in cardiovascular imaging.
Repeated testing and traditionally high radiation dose examinations means that cardiac imaging is responsible for a major proportion of radiation exposure due to medical imaging.
(Fazel et al.,
2009)
Radiation induced carcinogenesis is a potential risk of computed tomography (CT) imaging.
It has been estimated that in the US between 0.4 and 2% of all cancers are due to radiation exposures due to CT imaging.
(Brenner & Elliston,
2004)
Investigations for patients with suspected or known coronary artery disease frequently involves CT.
Coronary artery calcium scoring (CACS) from non-contrast CT is an established method for the assessment of cardiovascular risk.
Computed tomography coronary angiograph (CTCA) can accurately assess coronary atherosclerotic plaque burden and has a diagnostic accuracy for the assessment of stenosis severity approaching that of invasive coronary angiography.
In addition,
newer methods such as CT myocardial perfusion imaging and CT derived fractional flow reserve (CT-FFR) can assess the functional significance of coronary artery stenosis.
Non-contrast CT images for CACS are usually acquired using standardized imaging parameters (120kV,
filtered back projection reconstruction algorithm and 3x3mm slices) in order to provide consistent values.
However,
the application of radiation dose reduction techniques,
such as lower tube current and iterative reconstruction algorithms,
have the potential to reduce radiation dose.
Radiation exposure from CTCA has decreased rapidly since the early studies.
In the CORE64 study published in 2009 the radiation dose of CTCA was 14 mSv (millisieverts) for men and 15 mSv for women.
(Miller et al.,
2008) More recently CTCA with a radiation dose below 1 mSv has been described.
(Achenbach et al.,
2010)
Radiation dose reduction techniques in cardiac CT include individualized patient tailored imaging,
tube voltage reduction,
tube current modulation,
heart rate reduction,
minimizing the detector range,
prospective electrocardiogram gating,
and iterative reconstruction.
(Figure 1)
Our group has embarked on a series of research and audit projects with the aim of reducing radiation dose while maintaining image quality in cardiac CT in a clinical setting.