en Radiation Biology Radiation Biology یادداشت فنی Technical Note <div style="text-align: justify;">Background: The use of various types of radioactive drugs has increased the usefulness of nuclear medicine. The efficiency of the labeling radioactive isotope ^99mTc is crucial for the accuracy and reliability of an examination. We conducted a survey on the quality control (QC) of radioactive isotopes (RI) by measuring their purity. Materials and Methods: The QC (always or necessary) of radiopharmaceuticals was confirmed in 12 medical institutions in a metropolitan area. The radiochemical purity (RCP) of ^99mTc-HDP and ^99mTc-phytate was determined based on the measured radionuclide purity of ^99mTc containing ⁹⁹Mo. In addition, the effect of time after labeling and time after elution was analyzed. Results: None of the 12 hospitals regularly performed QC, and five hospitals administered QC when necessary. The average of 30 measurements of the ⁹⁹Mo content in ^99mTc from three manufacturers was 0.0109 for A, 0.0121 for B, and 0.0114 for C. The average labeling efficiency was 96.02% for ^99mTc-HDP and 94.97% for ^99mTc-phytate after labeling. The labeling efficiency of ^99mTc-HDP with different times after elution was 97.56%, 95.41%, 94.86%, 93.76%, and 91.89% after 0.5, 2, 4, 6, and 8 h, respectively, and that for ^99mTc-phytate was 97.21%, 97.21%, 94.42%, 93.35%, and 89.91% after 0.5, 2, 4, 6, and 8 h, respectively. Conclusion: We analyzed the degree of maintenance needed for labeling efficiency. The degree of change should be provided to the clinical practitioner as basic data for the QC of the radiopharmaceutical.</div> Quality control, 99mTc-HDP, 99mTc-phytate, labeling, nuclear medicine. 179 183 http://ijrr.com/browse.php?a_code=A-10-1-854&slc_lang=en&sid=1 Y.H. Jeon 7900319475328460015457 7900319475328460015457 No Department of Radiology, Ewha Womans University Hospital of Korea Y.H. Cho 7900319475328460015458 7900319475328460015458 No Department of Nuclear Medicine, Inha University Hospital of Korea J.H. Jung 7900319475328460015459 7900319475328460015459 No Department of Radiation Oncology, Soonchunhyang University Hospital of Korea J.H. Choi radiogra1@ansan.ac.kr 7900319475328460015460 7900319475328460015460 Yes Department of Radiological Technology, Ansan University of Korea