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Purpose: Dose received by organs at risk (OAR) in high-dose-rate (HDR) intracavitary brachytherapy (ICBT) for locally advanced cervical cancer impacts the late toxicity profile of the treatment. In the present study, we analyzed the inter-fraction variations of the minimum dose received by the most irradiated 2cc volumes (D2cc) of the OARs in ICBT. Methods and Materials: This prospective study included 40 patients with cervical cancer stage FIGO IIB-IVA treated with HDR ICBT and concomitant chemoradiotherapy with Computerized tomography (CT)- based three-dimensional planning. In addition, for 20 (of the 40) patients, the first fraction plan was superimposed on the second fraction images for studying its dosimteric impact on the OAR. The D2ccdata for the OAR was statistically analyzed for interfraction variations with Chi-square test or Fisher exact test as applicable. Paired t-test was used to compare the difference in means for the D2ccvalues between the three fractions. Results: The interfraction variations of the D2ccvalues of the OAR were statistically insignificant having P = 0.41, 0.8, and 0.20 for bladder, rectum, and sigmoid, respectively. Further, in 6 out of 20 cases, wherein first fraction plan was superimposed on second fraction images, the OAR doses exceeded the prescribed tolerance limits. Conclusion: We did not find variations in the OAR doses when each fraction was planned and treated individually. However, we found that if a single plan is used to treat subsequent fractions, OAR doses may exceed tolerance in about 30% of the cases. We believe that a larger sample size with improved compliance of bladder and bowel protocols would be needed to arrive at definitive conclusions.

Purpose: Dose received by organs at risk (OAR) in high-dose-rate (HDR) intracavitary brachytherapy (ICBT) for locally advanced cervical cancer impacts the late toxicity profile of the treatment. In the present study, we analyzed the inter-fraction variations of the minimum dose received by the most irradiated 2cc volumes (D2cc) of the OARs in ICBT. Methods and Materials: This prospective study included 40 patients with cervical cancer stage FIGO IIB-IVA treated with HDR ICBT and concomitant chemoradiotherapy with Computerized tomography (CT)- based three-dimensional planning. In addition, for 20 (of the 40) patients, the first fraction plan was superimposed on the second fraction images for studying its dosimteric impact on the OAR. The D2cc data for the OAR was statistically analyzed for interfraction variations with Chi-square test or Fisher exact test as applicable. Paired t-test was used to compare the difference in means for the D2cc values between the three fractions. Results: The interfraction variations of the D2cc values of the OAR were statistically insignificant having P = 0.41, 0.8, and 0.20 for bladder, rectum, and sigmoid, respectively. Further, in 6 out of 20 cases, wherein first fraction plan was superimposed on second fraction images, the OAR doses exceeded the prescribed tolerance limits. Conclusion: We did not find variations in the OAR doses when each fraction was planned and treated individually. However, we found that if a single plan is used to treat subsequent fractions, OAR doses may exceed tolerance in about 30% of the cases. We believe that a larger sample size with improved compliance of bladder and bowel protocols would be needed to arrive at definitive conclusions. [ABSTRACT FROM AUTHOR]

Rectal associated complications secondary to intracavitary brachytherapy of cervical cancers has long been among the main concerns of practitioners. The heterogeneous doses produced by brachytherapy enhances the probability of hotspots formation and morbidities in organs at the risk (OARs). Although different studies have focused on correlating inter-fraction/application D2cc dose variations with OARs morbidities, few have focused on their spatial location variation. This retrospective study evaluates the relation between inter-fractional variations in localization of rectum hot spots and observed morbidities. • Rectal associated complications induced by cervical brachytherapy were studied. • Hot spots were determined by calculating total EQD2 thresholds. • Distance of the inferior aspect of the pubic symphysis to hot points were measured. • A variation coefficient value < 1.5 indicates the repeatability of the hot spot. • High focal dose to one region increased risk of late radiation proctitis. [ABSTRACT FROM AUTHOR]