Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Effect of technetium-99m on iodine-131 thyroid uptake measurements

Journal Article · · J. Nucl. Med. Technol.; (United States)
OSTI ID:5877000
Following administration of 2.5-5.0 mCi(/sup 99m/Tc)pertechnetate, several hundred microcuries may be present in the necks of hyperthyroid patients after 6 hr. Coincidence summing of Tc-99m photons may disturb I-131 uptake measurements in such patients if an oral diagnostic dose of I-131 is administered immediately after completion of a (/sup 99m/Tc)pertechnetate scintigram. Using a lower discriminator level of 300 keV, false increases of 10%-50% may occur at 6 hr. The 24-hr uptake is also affected if an I-131 predose measurement is performed after administration of the Tc-99m dose. The authors have shown that these errors may be prevented by using a 1-mm lead filter in front of the scintillation detector. The attenuation of Tc-99m photons by the filter effectively eliminates summation pulses while it reduces the I-131 count rate by approximately 28%.
Research Organization:
Tygerberg Hospital, South Africa
OSTI ID:
5877000
Journal Information:
J. Nucl. Med. Technol.; (United States), Journal Name: J. Nucl. Med. Technol.; (United States) Vol. 13:2; ISSN JNMTB
Country of Publication:
United States
Language:
English