Keywords:
Contrast agents, Radiation physics, Radioprotection / Radiation dose, CT, Contrast agent-intravenous, Dosimetry, Dosimetric comparison
Authors:
M. Mazloumi1, G. Van Gompel1, T. Van Cauteren1, P. D. Deak2, J. de Mey1, N. Buls1; 1Brussels/BE, 2Berlin/DE
DOI:
10.26044/ecr2019/C-2340
Conclusion
In contrast-enhanced CT,
the presence of contrast agent increases the absorbed dose in organs and tissues.
The dose increase approximates a linear trend for a clinical range of iodine concentrations (< 20 mg/ml).
Results of simulations on a virtual aorta model shows the net physical effect of iodine concentration on the absorbed dose.
The agreement between the simulated dose results of the experimental and the virtual aorta models demonstrate the reliability of our simulations.
Moreover, the non-linear increase of the dose versus iodine concentration for the high iodine concentrations (Fig.
2) can be explained as the cupping shape in the dose profile of the aorta (iodine syringe) is much more pronounced for high iodine concentrations.
The dose enhancement factors (Fig.
5),
defined as the dose in the presence over the dose in the absence of iodine contrast agent,
increase with the iodine concentration and decrease with the kVp.
This result can be explained as the probability of photoelectric absorption in iodine is higher for lower energies that proximate its k-edge [10],
[11].
The impact of contrast agents on patient organ dose and its relation with iodine concentration needs to be considered in the dosimetry guidelines and CT protocols.
We propose to use kVp-Iodine concentration-dependent dose enhancement factors (Fig.
5) in contrast-enhanced CT.