Biological dosimetry for iodine contrast medium and X-ray interactions by cell survival

Abstract

In the presence of an iodinated contrast medium, X-ray absorption is enhanced owing to photoelectric interactions. This has been shown both experimentally and in patients undergoing radiographic procedures using contrast media (Adams et al, 1977; Norman et al, 1978; Callisen et al, 1979; Cockran et al, 1980; Matsudaira et al, 1980; Matsubara et al, 1982). Chromosome aberration assays of circulating lymphocytes in these patients revealed a significant increase in absorbed dose compared with those who underwent a similar radiological procedure without the use of contrast media. This effect is most significant at X-ray energy levels just above the binding energy of iodine K electrons. Ejected photoelectrons are estimated to deposit their energy within a few micrometers in tissue (Cole, 1969). In angiography, an iodine contrast medium is irradiated in small blood vessels so that attenuation and “hardening” of X rays are unlikely to be significant. However, when a larger volume of tissue is irradiated in the presence of a contrast medium, the X rays become not only attenuated but also “hardened” as they travel through the iodine-containing tissue. In contrast to the incident X rays, the exit X rays are predicted to be less effective in eliciting photoelectric interactions because of the reduction in the “soft” component of the X-ray spectrum. In this communication we report measurements of the dose enhancement as a function of iodine concentration and the effect of X-ray hardening on the photoactivation using biological dosimetry based on cell survival.

Forward dose perturbation at high atomic number interfaces in kilovoltage x‐ray beams

“…[32][33][34] Pronounced cell killing and tissue damage has also been reported by various groups, when a high-Z medium was maintained in contact with the cells and tissues. [35][36][37][38] Rosengren et al 37 showed that when cells were exposed in contact with a titanium plate dramatic cell killing was observed. Clinical trials using the composite effects of backscatter and forward scatter from high-Z media in kilovoltage beams are also being conducted to exploit selective dose enhancement in tumors.…”

Geant4 Monte Carlo simulation of absorbed dose and radiolysis yields enhancement from a gold nanoparticle under MeV proton irradiation

“…Distribution of radiolytic species as a function of radial distance for three incident proton energies(2,5, 10 MeV) for the GNP and WNP, at 10 ps after irradiation.…”

Abdominal Helical CT: Milk as a Low-Attenuation Oral Contrast Agent

“…There is some evidence that a bariumor iodine-based oral contrast medium may increase the local absorbed dose of the intestinal mucosa by as much as five times as a result of photoelectric interactions at the contrast agent-mucosa interface (20,21). This may be important in modern multiphase scanning, and milk may be used as an alternative contrast agent.…”