PO20: Quantitative Safety Evaluation for Treatment Procedures of Radioactive Isotopes

Abstract

<h3>Purpose</h3> To evaluate the safety level of the procedure of nuclear medicine isotopes quantitatively with a severity indication function for the operators. <h3>Materials and Methods</h3> A facility practices in some nuclear medicine procedure besides Ir-192 for HDR brachytherapy. The nuclear medicine procedures using different isotopes such as Iodine-131, Xofigo (Ra223 dichloride) and Lutathera (Lu-177 dotatate). And typical prescription activities were 10Ci for Ir-192, 30mCi for I-131, 0.2mCi for Ra-223 and 200mCi for Lu-177. A severity indication function S (A, t, N, M, L) was applied to evaluate safety level during these procedures. The severity indication function varies with vtime, distance, number of person encounter, and source activity. The function is illustrated in the attached figure. The prescribed radioactive isotope carried by operator from hot lab to treatment room, the quantitative values of severity indication function were calculated by changing of the travel time and number of encountered personnel and the distance travel between the hot lab and treatment room. The values of the severity indication function were computed for these different radioactive isotopes. <h3>Results</h3> In the selected facility, the distance was 18 meters from preparation hot lab to treatment location, and the procedure was taken 20 seconds. The radiation level to the operator was designed at the level of 7.0mR/hr. In the formula, N and M were treated as unit. the computed value for severity function was changed from 0.004, 0.060, and 4.000 for Xofigo, Radioactive Iodine 131 and Lutathera procedure with unit at Ci per square meters. The difference is 15 and 1000 times for I-131 and Lu-177 while Ra-223 as reference. <h3>Conclusions</h3> A severity indication function was used to quantitatively evaluation of the safety level of during isotopes conveying procedures. And an improvement of the computation accuracy could include gamma radiation component, and contribution related to isotope preparation and delivery to patients. Moreover, the analytical function could be applied in complex situations. Furthermore, this computed method could be used for facility designer in considering radiation protection requirement and procedure optimization.