Estimating the Absorbed Dose of Organs in Pediatric Imaging of (99m)Tc-DTPATc-DTPA Radiopharmaceutical using MIRDOSE Software

INTRODUCTION: In this study, organ radiation doses were calculated for the renal agent (99m)Tc-DTPATc-DTPA in children. Bio-kinetic energy of (99m)Tc-DTPATc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques. MATERIAL AND METHODS: In this applied research, fourteen children patients (6 males and 8 females) were imaged using a series of planar and SPECT images after injecting with technetium-(99m)Tc-DTPA diethylenetriaminepentaacetic acid ((99m)Tc-DTPATc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups. RESULTS: Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were 213.5±47.8, 12.97±6.23, 12.0±2.5, 4.29±1.47, and 3.31±0.96, respectively. Furthermore, the mean effective dose was 17.5±3.7 µSv/MBq. There was not any significant difference in the mean absorbed dose of the two groups. CONCLUSION: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with (99m)Tc-DTPATc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended.