Ultrasound-based conformal planning for gynaecological brachytherapy

This report describes the evolving use of transabdominal ultrasound (TAUS) as an imaging tool to verify tandem placement, localize the treatment volume and aid conformal brachytherapy planning for both cervical and uterine corpus cancers. Two patients, one with cancer of the cervix and one with cancer of the endometrium, are used as examples to illustrate the advantages of using TAUS. TAUS is used to guide applicator insertion and check the applicator in the treatment position. The dimensions of the uterus are recorded. Brachytherapy isodose plans are generated based on these measurements. Confirmation of uterine dimensions and isodose coverage is obtained using MRI taken after the initial fraction of treatment has been delivered. We illustrate how TAUS is successfully used to correct and verify tandem placement after the patient has been moved from insertion to treatment position. We also show how to use TAUS for conformal planning, based on individually derived target dimensions. TAUS has successfully been used to conformally plan treatment to the uterus and cervix, minimizing brachytherapy-related toxicity to surrounding structures. Ultrasound is portable, inexpensive and simple to use and allows for accurate, conformal, reproducible and adaptive treatments.