Renal imaging with different radiopharmaceuticals plays an essential role in diagnosing kidney diseases. Patients undergoing PET or SPECT renal scans receive a radiation dose that must be evaluated. It is imperative to acknowledge that pediatrics exhibit heightened sensitivity to radiation in contrast to adults. This research calculated absorbed doses in various organs and the effective dose per unit activity administered to pediatric patients aged one and five years undergoing renal SPECT scans using ^99mTc-(DTPA, DMSA, MAG3, and EC). To achieve this objective, reference voxel phantoms representative of one- and five-year-old pediatrics, as stipulated in the International Commission on Radiological Protection (ICRP) Publication 143, were scrutinized employing the GATE simulation framework. The findings of this study were compared with the corresponding data stipulated in ICRP128, which pertains to stylized phantoms. The outcomes underscore that one-year-old subjects exhibit a higher effective dose in comparison with their five-year-old counterparts. Moreover, the radiopharmaceutical ^99mTc-DMSA yielded the most substantial effective dose, while ^99mTc-DTPA and ^99mTc-EC (Normal renal function) registered the lowest effective dose for both one- and five-year-old patients. It is notable that, except ^99mTc- (DTPA-Abnormal and DMSA), the absorbed dose by the bladder wall exerts the most pronounced influence on the effective dose values across all cases. By comparing the absorbed dose of the organs obtained in this research with the reported data of ICRP128, fundamental differences were revealed in some organs. Additionally, effective doses per unit activity administered calculated in this research emerge as comparatively lower than the corresponding data reported in ICRP128.