| Abstrakt: |
Dose calibrator linearity testing is indispensable for evaluating the capacity of this equipment in measuring radioisotope activities at different magnitudes, a fundamental aspect of the daily routine of a nuclear medicine department, and with an impact on patient exposure. The main aims of this study were to evaluate the feasibility of substituting the radioisotope Fluorine-18 (18F) with Technetium-99m (99mTc) in this test, and to indicate it with the lowest operational cost. The test was applied with sources of 99mTc (62 GBq) and 18F (12 GBq), the activities of which were measured at different times, with the equipment preadjusted to measuring sources of 99mTc, 18F, Gallium-67 (67Ga), and Iodine-131 (131I). Over time, the average deviation between measured and expected activities from 99mTc and 18F were, respectively, 0.56 (±1.79)% and 0.92 (±1.19)%. The average ratios for 99mTc source experimental activity, when measured with the equipment adjusted for measuring 18F, 67Ga, and 131I sources, in real values, were, respectively, 3.42 (±0.06), 1.45 (±0.03), and 1.13 (±0.02), and those for the 18F source experimental activity, measured through adjustments of 99mTc, 67Ga, and 131I, were, respectively, 0.295 (±0.004), 0.335 (±0.007), and 0.426 (±0.006). The adjustment of a simple exponential function for describing 99mTc and 18F experimental activities facilitated the calculation of the physical half-lives of the radioisotopes, with a difference of about 1% in relation to the values described in the literature. Linearity test results, when using 99mTc, through being compatible with those acquired with 18F, imply the possibility of using both radioisotopes during linearity testing. Nevertheless, this information, along with the high potential of exposure and the high cost of 18F, implies that 99mTc should preferably be employed for linearity testing in clinics that normally use 18F, without the risk of prejudicing either the procedure itself or the guarantee of a high-quality nuclear medicine service. [ABSTRACT FROM AUTHOR] |
