It is possible to visualize the radioelements present in contaminated cells, biological tissues or organs using autoradiography techniques. Knowing the advantages and limitations of each one is essential to improve the evaluation of radiation doses received by living organisms and, ultimately, the monitoring of operators working on dismantling worksites.
Researchers from the radiotoxicology laboratory at the Institut François-Jacob, in collaboration with the College of Optical Sciences (University of Arizona) compared 3 autoradiography techniques. The first consists in immersing the contaminated sample in an emulsion of silver ions that are transformed into silver metallic atoms via radiation. The second technique is based on placing the sample in contact with a plastic film that is sensitive to radiation. The traces left by the radiation are amplified by a chemical solution, digging "holes" in the plastic film. The third technique is digital. A camera is coupled to a scintillation counter: when excited by ionizing radiation, it emits light that is captured by the camera.
The researchers used several samples (macrophage, lung, muscle and skin cells) contaminated by different actinides: plutonium, americium, or a mixture used as fuel in civilian nuclear reactors (MOX).
The three techniques prove to be complementary, with different specifications in terms of resolution, quantification, and acquisition speed. Interestingly, the camera generates images in real time. Thus, it can provide a quick overview of the distribution of contaminants in a tissue, unlike the other two techniques that require long exposures. This characteristic can be very useful, for example, when analyzing a skin biopsy of someone injured during a dismantling operation, or when many contaminated biological samples must be quickly screened during a nuclear accident.