ABSTRACT
Objective@#To investigate the changes of ambient dose equivalent rate in 99mTcO4- single photon emission computed tomography (SPECT) of the thyroid among patients with hyperthyroidism, so as to provide insights into radiation protection guidance.@*Methods@#Patients with hyperthyroidism who underwent 99mTcO4- SPECT of the thyroid in a tertiary hospital were enrolled. The ambient dose equivalent rate was measured at different time points following 99mTcO4- infection and at sites with different distances from patients' neck, and the effects of time post-injection, distance from patients' neck, 24-hour thyroidal radioiodine uptake and thyroid weight on the ambient dose equivalent rate were examined using a generalized linear mixed model.@*Results@#Totally 100 patients with hyperthyroidism were enrolled, including 24 men and 76 women and with a mean age of (38.5±14.0) years. The generalized linear mixed model was statistically significant (F=6 610.165, P<0.001), and patients' thyroid weight, time post-injection and distance from patients' neck significantly affected the ambient dose equivalent rate (F=57.967, 15 988.574, 11 200.645, all P<0.001), and the ambient dose equivalent rate positively correlated with patients' thyroid weight and negatively correlated with time post-injection and distance from patients' neck.@*Conclusions@#The ambient dose equivalent rate is affected by patients' thyroid weight, time post-injection and distance from patients' neck among patients with hyperthyroidism undergoing 99mTcO4- SPECT of the thyroid. Delay in contact with patients or keeping distance from patients may be effective for radiation protection.
ABSTRACT
Objective To prepare and explore the pharmacokinetic parameters for ~ 99 Tc~ m -ASON-EGF in healthy rabbits. Methods ~ 99 Tc~ m -ASON-EGF was prepared according to previous methods and its changes of concentration in blood were measured by radioactivity counts per minute. The experimental data were dealt with by 3p97 software and its true compartment model was estimated by AIC value, R~ 2 value, the 1/c and F test. Subsequently, its half-life of distribution (T_ 1/2 ?), half-life of elimination (T_ 1/2 ?), central compartment volume of distribution (Vc), total apparent volume of distribution (Vd) and total rate of clearance (CL) were calculated by the software. Finally, the binding rate of plasma protein was determined by trichloroacetic acid precipitation. Results The best model of ~ 99 Tc~ m -ASON-EGF in vivo was two-compartment model and its T_ 1/2 ?, T_ 1/2 ?, Vc, Vd and CL were 5.28 min, 89.23 min, 67.8 ml, 915.6 ml and 7.1 ml/min respectively. After being incubated with fresh plasma for 1.5 h, its binding rate was 10.69%. Conclusion Its process of transportation in healthy rabbits is fitted to two-compartment model and the pharmacokinetic properties are desirable.