Dosimetric comparison of the Fletcher family of gynecologic colpostats 1950-1980.

The Fletcher gynecologic applicator was developed for irradiation of carcinoma of the uterine cervix in the early 1950's. Since that time, numerous modifications and changes have been made in the colpostat construction and in the location of the shields that provide a reduced dose to the bladder trigone anteriorly and to the rectal wall posteriorly. The original applicators include the preload radium double colpostat and the preload radium single colpostat. In the 1960's, afterloading colpostats were manufactured as the Fletcher-Suit and the Fletcher-Green devices. With the introduction of the Delclos mini-colpostat, a new generation of applicators followed in the 1970's. The Fletcher-Suit-Delclos colpostat recently manufactured by two companies can be used as a mini-colpostat. By adding a shield-containing cap, these applicators function as the original Fletcher colpostat. With the development of new applicators over the past 30 years, numerous changes in the position of the shields and, therefore, the dose transmitted to the surrounding tissues have been made. This paper describes dosimetric evaluation of all of these applicators and the various changes that have occurred through the generations of Fletcher colpostats in an attempt to provide information for radiation therapists and gynecologists who are using these instruments in their clinical practice.