Study of Patient's Position to Reduce Late Complications in High Dose Rate Intracavitary Radiation of the Uterine Cervix Cancer / 대한방사선종양학회지

ABSTRACT

PURPOSE: Radiation proctitis and radiation cystitis are frequent and problematic late complications in patients treated with radiation for the uterine cervix cancer. Authors tried to find out the better patient's position in high dose rate intracavitary radiation to reduce the radiation dose of bladder and rectum. MATERIALS AND METHODS: In 13 patients, Foley catheters were inserted to patients' bladder and rectum and were ballooned with radioopaque dye. After insertion of a tandem and two ovoids, semi-orthogonal anteroposterior and lateral films were taken in both lithotomy and supine position. The rectal point and bladder point were defined according to the criteria recommended in the ICRU Report 38 with modification. Using these films, all patients' bladder and rectal dose were calculated in both positions (the radiation dose of A point was set to 400 cGy). And also, the distance of bladder and rectum from uterine cervical os was calculated in both positions. RESULTS: The average radiation dose of rectum was 240.7 cGy in lithotomy position and 278.3 cGy in supine position, and the average radiation dose of bladder was 303.5 cGy in lithotomy position and 255.8 cGy in supine position. After the paired t-test, the radiation dose of rectum in lithotomy position was marginally significantly lower than that in supine position, while the radiation dose of bladder in lithotomy position was significantly higher than that in supine position. On the other hand, the average distance between rectum and cervical os was 35.2 mm in lithotomy position and 32.3 mm in supine position. and the average distance between bladder and cervical os was 30.4 mm in lithotomy position and 34.0 mm in supine posi-tion. After the paired t-test, the distance between rectum and cervical os in lithotomy position was significantly longer than that in supine position, while the distance between bladder and cervical os in lithotomy position was significantly shorter than that in supine position. CONCLUSION: The radiation dose of bladder can be reduced in supine position and the radiation dose of rectum can be reduced in lithotomy position, so we can choose appropriate position in each patient.