An evaluation of the shielding effectiveness of lead aprons used in clinics for protection against ionising radiation from novel radioisotopes

The purpose of this study is to evaluate the effectiveness of personal radiation shields currently worn in hospital and other diagnostic environments. This study was performed with four different radioisotopes; 18F, 99mTc, 124I and 131I. 18F results showed a decrease in dose with 0.5-mm Pb shielding but the reduction provided does not warrant its use clinically. 124I testing demonstrated that dose enhancement can occur in greater shield thicknesses. PET isotope 124I can be adequately shielded using 0.25-mm Pb equivalent aprons but any higher thickness increase the wearer's dose. As a result more shielding does not always equal more protection. The 131I test showed that no dose reduction occurred, even when tested with up to 1.25-mm Pb equivalent shielding. Novel radioisotopes being used in the laboratory and clinic should be individually tested as each requires specific shielding testing.