Abstract:
The main objective of this study was to evaluate the thyroid uptake of technetium-99m using gamma camera and dose calibrator methods in National Cancer Institute. This study included 64 patients (90.6% females and 9.4% male) in the age range between 13 - 81 years, with 43.8% of them in age group 31- 48 years and mean of 37.25±14.58 years. The study was done using two methods for dose calibration, gamma camera planar system with pinhole collimator and dose calibrator at distance of 5cm and 7cm from collimator to patient's neck. The duration of the study was from March 2019 to July 2019.
The study showed that the thyroid uptake values using dose calibrator method were more consistent with radiation protection principles of minimizing the exposure to radiation for staff. The method was also had higher values than those measured with gamma camera due to the scatter radiation in the method of gamma camera. Finally, the study revealed that the correlation between the two methods was given by the R-Square of 0.9937 at 5cm distance and 0.9591 at 7cm distance. According to this coefficient there was no big difference in uptake between the two methods especially at 5cm object-to-pinhole distance, which gave the best result for optimum imaging in 99mTc-pertechnetate thyroid uptake test due to minimum distance.
