Positional Change of the Uterus during Definitive Radiotherapy for Cervix Cancer

Park, Won; Huh, Seung Jae; Lee, Jeung Eun

Abstract

PURPOSE: The purpose of this study was to investigate the positional change of the uterus during radiotherapy
MATERIALS AND METHODS
Between 1997 and 2001, 47 patients received definitive radiotherapy for cervical cancer at the Samsung Medical Center. For each patient, two MRI scans were taken; one before and the other 3~4 weeks after the radiotherapy treatment. In T2 weighted MRI images, the positional change of the uterine was quantified by measuring six quantities; the distance from the cervix os to the isthmus of the uterus (Dcx), the maximum length from the isthmus of the uterus to the uterine fundus (Dco), the maximum vertical distance of the uterine body (Dco-per), the angle between the vertical line and the cervical canal in the sagittal images (Acx), the angle of the uterine corpus from the vertical line in the sagittal plan (Aco-ap), and the relative angle of the uterine corpus from a fixed anatomical landmark in the axial images (Aco-axi).
RESULTS
The mean Dcx values, before and during the treatment, were 36.7 and 27.8 mm, respectively. The Dco deviated by more than 10 mm in 14 cases (29.8%). The change in the Acx ranged from 0.1 to 67.8degrees (mean 13.2degrees). The Aco-ap changed by a maximum of 84.8degrees (mean 16.9degrees). The differences in the Dcx plus the Dco in the smaller (<4 cm) and larger (>or= 4 cm) tumors were 5.3 and 19.4 mm, respectively. With patients less than 60 years old, or with a tumor size larger than 4 cm, the difference in the Acx was statistically significant.
CONCLUSION
The positional changes of the uterus, during radiation treatment, should be considered in the 3DCRT or IMRT treatment planning, particularly in patients under 60 years of age or in those with a tumor size greater than 4 cm in maximum diameter.