Background: Patients with reduced renal function may be at risk of contrast medium-induced acute kidney injury
(CI-AKI) following intravenous iodine contrast medium (CM) enhanced computed tomography (CT). Reducing the
CM dose may reduce this risk. Decreasing the X-ray tube potential (kilovoltage, kV) from commonly used 120 to
80 kV results in higher CM attenuation due to the photoelectric properties of iodine, which may permit reduction
of the iodine dose while keeping the attenuation unchanged. Lower tube potential, however, increases image
noise which may be controlled by increasing the X-ray tube loading (milliampere seconds, mAs) to keep image
quality, e.g. contrast-to-noise ratio (CNR) unchanged. Complete compensation of tube loading increases the
radiation dose to the patient, but the introduction of noise reducing iterative reconstruction algorithms may prevent
Aim: To investigate if low-kV CT with reduced CM doses is a feasible alternative in examinations of the thorax
and abdomen in patients considered at risk of CI-AKI.
Material and methods: In three cross-sectional studies 80-kV CT protocols with 40-50% reduction of CM dose
and increased tube loading to control image noise was compared with standard 120-kV protocols, in two studies
to diagnose pulmonary embolism and in one hepatic study. Based on a phantom study and a clinical hepatic CT
study, iterative reconstruction algorithms were used to control image noise with no increase in tube loading. Image
quality was evaluated objectively and subjectively.
Results: Using 80-kV CT protocols with reduced CM doses (40-50%) and mAs compensation seems to provide
satisfactory diagnostic quality in pulmonary CT angiography and hepatic CT for patients with GFR <45-50 mL/min
and a body mass index <30 kg/m2. However, the use of iterative reconstruction algorithms to control image noise
without increased mAs resulted in inferior subjective image quality.
Conclusion: Using low-kV CT protocols with reduced CM dose could benefit patients at risk of CI-AKI. The
usefulness of iterative reconstruction algorithms to control image noise and not increase radiation dose remains