Design of an afterloading vaginal applicator (MIRALVA)

A vaginal applicator was designed and constructed that incorporates two ovoid sources and a central tandem which can be utilized to treat the entire vagina (alone or in combination with the uterine cervix). The average surface dose rate around the 2 cm ovoids is 120 cGy/hr and in the 2.5 cm diameter vaginal cylinder about 100 cGy/hr with usual loading of 20 mg Ra eq 137-Cs sources in the ovoids and 10-15 mg Ra eq 137-Cs sources in the cylinder. The applicator has vaginal apex caps and additional cylinder sleeves that allow for increased dimensions. The tandem in the uterus can be utilized when clinically indicated using standard loadings, depending on the depth of the uterus (20-10-10 or 20-10 mg Ra eq). When the tandem and vaginal cylinder are utilized the strength of the sources in the ovoids should be 15 mg Ra eq. The vaginal cylinder or uterine tandem never carry an active source at the level of the ovoids. Thermoluminescent dosimetry measurements throughout the surface of the applicator showed close agreement with the computer dose calculations (within +/- 2%). The acronym MIRALVA describes the device (Mallinckrodt Institute of Radiology Afterloading Vaginal Applicator).