Changes in applicator positions and dose distribution between high dose rate brachytherapy fractions in cervix carcinoma patients receiving definitive radiotherapy.

This study examines the change of applicator geometry and its effect on rectal/rectum (R) and bladder (B) doses, and obtained radiobiological equivalent doses (RED), between each high dose rate (HDR) brachytherapy (BT) fraction in cervical carcinoma patients. BT using a tandem (T) and two ovoids (O) is included, and any discrepancies in applicator positions among the fractions were calculated. Whether the change of applicator position had an effect on the calculated R and B doses was analysed.

Geometric and dosimetric variations of ICRU bladder and rectum reference points in vaginal cuff brachytherapy using ovoids.

Purpose: To investigate the interfractional geometric and dose variations of rectal reference point (R) and bladder reference point (BL) doses in patients receiving vaginal cuff irradiation using high-dose-rate brachytherapy with 2 ovoids and the change in calculated radiobiologic-equivalent dose of R and BL.

Methods: ICRU-38 R and BL reference doses were calculated. The variation in positions of ovoids, R, and BL were determined.