Should the bladder be empty during intracavitary radiotherapy for carcinoma of the cervix?

Twelve patients with stage IIB carcinoma of the cervix were treated with intracavitary therapy using the Nucletron Ring applicators according to the following protocol: external beam therapy using antero-posterior portals at 190 cGy per fraction for 24 fractions, 4 fractions per week and intracavitary therapy of 490 cGy weekly to point A on the 5th day of treatment for 5 weeks. Dosimetry was performed to analyze the dose to the bladder with the bladder full and empty. When the bladder was empty, the radiation dose to its anterior surface ranged from 106-126 cGy with a mean of 114.5 cGy, and that reaching the posterior surface ranged from 242-340 cGy with a mean of 297.1 cGy. When the bladder was full, the dose to the anterior surface of the full bladder in the pelvis ranged from 104-140 cGy with a mean of 122.08 cGy and the dose to the posterior surface ranged from 4940-8740 cGy with a mean of 6619 cGy. Thus, approximately 3-5 cm length of the posterior wall of the bladder receives a significantly higher dose if the bladder is treated full (p = 0.0000). Until better ways of shielding the bladder are developed it may be better to treat with the bladder completely empty during intracavitary therapy for carcinoma of the cervix. (author). 4 refs., 2 figs., 1 tab