Inter-Fraction Variations of D2cc Brachytherapy Dose Received By Bladder and Rectum in Patients with Inoperable Cervical Cancer

Purpose: To examine the inter-fraction variations of the D2cc of the brachytherapy dose applied to bladder and rectum in patients with inoperable cervical cancer on the CT basis. Methods and Materials. This prospective study included 30 patients with cervical cancer FIGO IIb-IVa stage who were treated with concomitant chemo-radiotherapy. Intracavitary brachytherapy was performed with applicators type Fletcher tandem and ovoids, once a week at the HDR regime (high dose rate). Computer tomography was made after every application. The analysis was made whether there is a statistically significant difference in the inter-fraction variations of the D2cc of the brachytherapy dose to bladder and rectum. Statistical significance of differences among the examined groups was tested with ANOVA test as well as the Tukey post-hoc analysis. The difference among the groups analyzed was considered significant if P<0.05. Results: Statistical significance has been found neither in the change of the dose for all fractions in relation to the first one nor by the post-hoc analysis by Tukey method for the differences in the dose for all fractions mutually for bladder (p=0.45) and for rectum (p=0.73). One standard deviation of the brachytherapy dose for bladder is 1.09Gy and for rectum it is 1.045Gy (15.6% and 15% of the prescribed dose). Conclusion: There is no significant inter-fraction change of the brachytherapy dose D2cc of the bladder and rectum during the inoperable cervical cancer brachytherapy. However, two standard deviations need to be included while calculating the total EQD2cc of the bladder and rectum.