Patient safety in CT - contrast media and dose management
Dose optimization and contrast agent administration are key parameters for patient safety.
If you like this page kindly support. Just subscribe or like the Page!
Approaches to dose reduction
CT examinations are responsible for around 60% of the medically caused radiation dose; their number has risen steadily in recent years. Andreas H. Mahnken, University of Marburg, gave an overview of approaches to improve patient safety.
“First things first,” said Mahnken, to remind patients of the individual indication for a CT as the most important measure. He also pointed out that the average dose values varied enormously between the different centers. This is due on the one hand to the different scanners, but on the other hand also depends on the users. “The low-dose concepts are not new, but we have to think about them anew every day,” he warned, declining ‘low dose’ as follows:
L ength of the scan area minimize investigations by Bischoff et al. (2009) showed that 70% of CT scans are performed with an overscanning of more than 3 cm.
O ptimierung of investigation and reconstruction patient preparation (gonad very effective, if it is not within the scanning area, and use of lens protection
High Pitch scanning
low kV imaging
iterative image reconstruction
Prospective ECG triggering
W eitreichende system optimization (with manufacturers)
D osismodulation Also feasible in 4D. The angle-dependent modulation even allows the radiation source to be partially switched off at certain angles of incidence.
O ator training; training of technologists and radiologists and regular evaluating their own actions and the doses achieved
S orgfältig and patient individually question the administered dose
E valuation of the applied radiation doses
Dealing with contrast media
The general toxicity of contrast media was actually no longer an issue since iodine was used, said Mahnken. It looks different when it comes to kidney toxicity. The viscosity of contrast media plays an important role here. The “ideal group of contrast agents” is therefore that of low osmolar substances. “The topic may also be overrated overall,” said Mahnken, citing a study by Newhouse (AJR 2008) in which the creatinine levels of 32,000 hospitalized patients were examined and increases were also documented in patients who had not received any contrast agent.
In the latest update of the ESUR (European Society of Urogenital Radiology) guidelines for contrast agent safety, the limit value for the glomerular filtration rate (GFR) has been reduced from 60 to 45 ml / min / 1.73 m 2 . “So now much worse kidney function values than before are accepted for contrast agent administration,” says Mahnken.
The incidence of allergies * is very low, as is the risk of extravasation, for which the contrast medium volume is primarily a risk factor, but not the needle or the viscosity.
Conclusion and outlook
"So, overall, no significant risks? No, it’s not that simple, ”said Mahnken. In the future, more personalized strategies have to come to the fore. This means that older patients have to worry more about the amount of contrast agent, while younger patients focus primarily on the radiation dose. The kV reduction is an important approach for this, but it is difficult to implement in obese patients. In the development of new contrast media, there are first attempts to use metal clusters with differently absorbing materials.