Analysis of High Dose Rate Intracavitary Radiotherapy (HDR-ICR) Treatment Planning for Uterine Cervical Cancer

Chai, Gyu Young

Abstract

PURPOSE: This study was done to confirm the reference point variation according to variation in applicator configuration in each fractioation of HDR ICR.
MATERIALS AND METHODS
We analyzed the treatment planning of HDRICR for 33 uterine cervical cancer patients treated in department of therapeutic radiology from January 1992 to February 1992. Analysis was done with respect to three view points-Interfractionation A point variation, interfractionation bladder and rectum dose ratio varidation, interfractionation treatment volume variation. Interfractionation A point variation was defined as difference between maximum and minimum distance from fixed rectal point to A point in each patient. Interfractionation bladder and rectum dose ration variation was defined as difference between maximum and minimum doe ratio of bladder or rectum to A point dose in each patient.. Interfractionation treatment volume variation was defined as difference between maximum and minimum treatment volume which absorbed over the described dose that is, 350 cGy or 400 cGy-in each patient.
RESULTS
The mean of distance from rectum to A point was 4.44cm , and the mean of interfractionation distance variation was 1.14cm in right side, 1.09cm in left side. The mean of bladder and rectum dose ratio was 63.8% and 63.1% and the mean of interfractionation variation was 14.9% and 15.8% respectively. With fixed planning administration of same planning to all fractionations as in first fractionation planning mean of bladder and rectum dose ration was 64.9% and 72.3% and the mean of interfraction variation was 28.1% and 48.1% respectively. The mean of treatment volume was 84.15cm3 and the interfractionation variation was 21.47 cm3.
CONCLUSION
From these data, it was confirmed that there should be adapted planning for every fractionation, and that confirmation device installed in ICR room would reduce the interfractionation variation due to more stable applicator configuration.