Abstract:Objective: To explore the ultrastructural changes of the prostate after three-dimensional conformal radiation therapy (3-DCRT) of benign prostatic hyperplasia (BPH).Methods: Ten canines of 7 ~ 15 years with spontaneous BPH were chosed as experimental models and were divided for 2 groups randomly. The prostate directly exposed to 3-DCRT.The whole prostate of per animal was the target and sorrounded by 90% isodose curve,and was subjected to irradiation of 6MV X-ray by 2Gy per time and the total dose of 14 Gy. We compared ultrastructural changes of prostate biopsy before and after irradiation for 1 and 3 month with the scanning electron microscopy. Results: Compared with the preirradiation samples, the postirradiation samples had glandular and smooth muscle atrophy, increased space between the glands,glandular cell shedding, and cavity formation.Conclusions: 3-DCRT can make and stroma shink thus reduce the prostate volume and improve urinary tract obstruction and LUTS.