Özet:

OBJECTIVE In this study, the effect of endorectal balloon (ERB) on risky organ doses was investigated in patients with low-medium risk prostate cancer treated with Stereotactic body radiotherapy (SBRT). METHODS In the 17 patients, CT simulation and treatment was performed with an empty rectum and no ERB was used (non-ERB group). ERB filled with 100-150 cc air into 15 patients was placed in the rectum and identified with the ERB group. SBRT was performed to be delivered with volumetric modulated arc, with 10 FFF photon beams, using a linear accelerator with a high definition MLC. Dosimetric parameters for the rectum, bladder and penilbulb were compared between the two groups as a retrospective. Independent samples t-tests were performed to examine the differences between the two groups. RESULTS The mean dose given to the rectum was lower in the ERB group than in the non-ERB group, and a statistically significant dose reduction of 149.4 cGy per fraction was found in the ERB group (p<0.01). Similarly, the mean dose given to the bladder was lower in the ERB group than in the non-ERB group, and a statistically significant dose reduction of 178.8 cGy per fraction was found in the ERB group (p<0.01). The mean dose of penilbulb was 373 cGy in the ERB group, while the mean dose of penilbulb was 1314 cGy in the non-ERB group. There was statistically significant differences between groups (p<0.01). CONCLUSION The use of high-volume ERB reduces rectum, bladder and penilbulb doses in prostate cancer patients treated with linac-based SBRT.

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