Introduction: Ionizing radiation is present in nuclear medical imaging, which requires appropriate protection for healthcare personnel and patients. Lead shielding is one of the commonly used methods to reduce exposure to ionizing radiation. Purpose: The purpose of
this study is to determine how the use of lead shielding and distance from the source of
ionizing radiation affect the radiation dose during work with commonly used
radiopharmaceuticals (Tc-99m and F18) in diagnostic imaging at the Department of Nuclear
Medicine. Methods: In this master's thesis, we used a descriptive method with a review of
existing literature, along with a quantitative approach with measurements conducted in the laboratory. In the research section where we employ a quantitative research method, all theories are confirmed through calculations and graphics. As part of the empirical work, we conducted measurements at the Clinic of Nuclear Medicine at the University Clinical Center
Ljubljana. The measurements were performed using the isotopes Tc-99m and F18 at different distances and with various thicknesses of lead shielding. Statistical analysis of the measurements was carried out using the SPSS software. Results: For Tc-99m, we demonstrated that the proportion of protection increases with the increase in the thickness of
lead shielding. Without lead shielding, the protection proportion is equal to 0%. At a lead
thickness of 0.206 mm, the protection proportion is 40.99%, which means that lead shielding
reduces radiation exposure by approximately 41%. The proportion of protection then
increases with the increase in lead thickness. At the maximum thickness of 1.964 mm, the protection proportion reaches 99.35%. In the second part of the measurements and statistical analysis, we proved that the use of lead aprons can reduce the absorbed radiation dose by up
to half. This is particularly effective when the photon energy is <140 keV. We also
demonstrated that at lower activities of Tc-99m, there are statistical differences when using
various thicknesses of shielding and distances. By conducting a statistical analysis, we have successfully demonstrated that distance also plays a significant role, across all utilized
radiopharmaceuticals and activities. Our study has revealed statistically significant differences among various distance levels, unequivocally indicating its influential impact.
Discussion and conclusion: Based on the obtained results, we can conclude that there are statistically significant differences between protective shields and unprotected radiation
sources, such as Tc-99m. However, no significant differences were found for high-energy
isotopes like F18. We also proved that there is a connection between the weight of the protective shield and its protective efficiency. In conclusion, the effectiveness and usefulness of radiation protection depend on the energy of radiation, type and thickness of the protective material, and distance from the radiation source.
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