Determination of Uterus Absorbed Dose by Patients following Myocardial Perfusion Scan using TLD and Conjugate View Methods

Introduction: The determination of patient’s absorbed dose is the first step of radiation protection which depends on the quantification of organ activity in nuclear medicine. The aim of the present study was to determine the absorbed dose by patient’s uterus following myocardial perfusion scan with ۹۹mTC-sestamibi using Theroluminescnce dosimetry (TLD) and conjugate-view methods. Material and Method: In this study, each patient was injected ۱۵ to ۲۰ mCi (based on their weight) of ۹۹mTC-sestamibi. Myocardial perfusion scan from twenty two patients (females) were acquired by gamma camera at ۱۵, ۶۰ and ۹۰ minutes after ۹۹mTC-sestamibi injection. To determine the amount of activity in uterus, conjugate view method was applied on images. Then, MIRD equation was used to estimate absorbed dose in uterus of patients. Moreover, uterus absorbed dose was determined using TLD method. At the end, absorbed dose values obtained in conjugate view method were compared with the data obtained from TLD method. Results: The average amount of uptake for ۹۹mTC-sestamibi by heart was calculated ۳.۰۷۷±۰.۰۶۷ percent of injected dose. The uterus activity at the intervals of ۱۵, ۶۰ and ۹۰ minutes after injection of ۹۹mTC-sestamibi was ۰.۰۴۴±۰.۰۱۵, ۰.۰۳۱±۰.۰۱۴ and ۰.۰۲۶±۰.۰۱۳ mCi, repectively. The uterus absorbed dose per unit of injected activity (mGy/MBq × ۱۰−۴) obtained ۵.۲۵۸±۰.۵۰۰ using TLD method. Conclusion: The results of this study were in good agreement with similar studies. Dosimetry using TLD, in comparison with the conjugate view method, demonstrates more accurate results.

Keywords:

Radionuclide Imaging , Myocardial Perfusion Imaging , Thermoluminescent Dosimetry , Uterus