Absorbed radiation dose to humans from technetium-99m-teboroxime

Area of Science:

• Nuclear Medicine
• Radiopharmacology
• Radiation Dosimetry

Background:

• 99mTc-teboroxime (Cardiotec) is a radiopharmaceutical used for diagnostic imaging.
• Accurate radiation dose estimation is crucial for patient safety in nuclear medicine procedures.
• Understanding tissue distribution and organ dosimetry is essential for evaluating radiopharmaceutical safety.

Purpose of the Study:

• To estimate the radiation absorbed dose to human organs following intravenous administration of 99mTc-teboroxime.
• To identify the target organs and assess the impact of gallbladder emptying rate on radiation dose.
• To determine the limiting organ for radiation exposure from 99mTc-teboroxime.

Main Methods:

• Quantitative SPECT was used to measure organ uptake in nine normal volunteers.
• Non-linear regression analysis of organ time-activity data was performed.
• The MIRDOSE 2 program was utilized to estimate absorbed radiation doses to organs.

Main Results:

• The gallbladder and upper large intestine (ULI) were identified as target organs.
• At a 6-hour gallbladder emptying interval, doses were 26.5 muGy/MBq to the gallbladder and 33.2 muGy/MBq to the ULI.
• The ULI dose remained constant at 33.2 muGy/MBq (123 mrad/mCi) across different gallbladder emptying intervals, making it the limiting factor.

Conclusions:

• The upper large intestine (ULI) receives the highest and most consistent radiation dose from 99mTc-teboroxime.
• Gallbladder emptying rate significantly influences gallbladder radiation dose but not ULI dose.
• Radiation dose to the ULI is the critical factor in determining the safety of 99mTc-teboroxime administration.