OBJECTIVETo assess the radioactive damage induced by interstitial 125I seed implantation to the rabbit urethra.

METHODSWe implanted 24 rabbits with 125I seeds 1.0 cm to the urethra at the radiation dose of 14.8 MBq (Group A), 29.6 MBq (Group B) and 44.4 MBq (Group C), while a non-radioactive seed was implanted near the urethra of the controls (Group D). Four weeks later, we detected the radiation-induced pathological and morphological changes in the urethra by H&E, light microscopy and electron microscopy.

RESULTSFour weeks after the implantation, no obvious histopathological and ultrastructural changes were observed in the urethral tissues of the experimental rabbits as compared with the control group. The scores on the radioactive damages to the urethra obtained by light microscopy were (2.20 +/- 0.18), (2.23 +/- 0.15), (2.27 +/- 0.10) and (2.10 +/- 0.17) respectively in Group A, B, C and D, with no significant differences between the first three groups and the control (P > 0.05). And the scores on the FlaMeng semi- quantitative analysis of mitochondria in the experimental groups were (1.23 +/- 0.13), (1.34 +/- 0.25) and (1.41 +/- 0.30) respectively, not significantly different from (1.12 +/- 0.13) the control (P > 0. 05).

CONCLUSIONThe radioactive damage induced by 125I seeds to the urethra increases with the enhanced radiation dose. Intraoperative implantation of 125I seeds at the prescription dose has no obvious adverse effect on the rabbit urethra.