Evaluation of Patients’ effective dose in nuclear medicine department of Isfahan in order to define a local reference level

Abstract

Introduction: Nowadays, nuclear medicine (NM) imaging indications in medical practice is raising. A practical step to get closer to the optimization rule is collecting data about patients’ exposure and definition of guidance levels. The aim of this study was definition of local reference level in Isfahan city. Materials and Methods: Questionnaires were given to two NM departments of Isfahan Hospitals. The data of age, gender, weight, type and activity of used radiopharmaceutical were collected for protocols of Bone (TC-MDP), Kidney (TC-DMSA), Kidney (TC-DTPA), Kidney (TC-EC), Thyroid (TC- Pertechnetate), Lung (TC-MAA), Cardiac (TC-MIBI) for adults and Bone (TC-MDP), Kidney (TC-DMSA), Kidney (TC-EC), Kidney (TC-DTPA) for pediatrics. The cardiac scan is performed in two-day Stress-Rest protocol. Results: 1540 patients (243 pediatric and 1297 adults) were included. The average injected activities in pediatrics were 5, 3, 2 and 5 mili-curies for MDP, DMSA, EC and DTPA respectively. These injected activities impose doses of 1.82, 1.91, 1.68, 2.32 mili siverts for pediatric patients. For adult patients the average activities were 22.5, 6.5, 8, 4, 12, 4, 21.5 and 19.5 mili-curies for protocols of MDP, DMSA, EC, MAA, DTPA, Pertechnetate, MIBI-Stress and MIBI-Rest respectively. Which impose effective total body doses of 4.75, 2.12, 2.07, 1.62, 2.17, 1.92, 6.29 and 6.49 mili siverts to adult patients respectively. Conclusion: It is the first study done in all ages to evaluate patients’ dose in NM in Iran. In these departments injected activities were based on patient weight and protocols were adapted with dose charts exists for adult and pediatric patients; so variations in doses were minimum. These charts were offered to radiation workers based on acceptable image quality, SPECT system sensitivity and patient dose. In comparison with guidance levels of other countries, patients’ received dose during in these Isfahan N.M centers were comparable with international diagnostic reference levels reported by the European commission and mettle et al 2008 and study of Niksirat et al, 2014 in Mazandaran. Injected activities for cardiac imaging are higher (40%) from study of Salimi et al 2015 in Tehran. This variations through the administrated dose in country makes it more critical to plan a national survey in order to offer a guideline in this country.