CHAPTER 5 - BRACHYTHERAPY

Abstract

Publisher Summary This chapter focuses on brachytherapy. The placement of radioactive material directly into or immediately adjacent to such volumes has been used successfully since radioactivity was first discovered. The advantage of this method is that very high doses can be delivered in a short time to small volumes without the delivery of excessive dose to adjacent normal tissue. The dose rates are very high near the radioactive sources but they fall off very rapidly within a few centimeters. The placement of radioactive sources in the uterus, around the cervix, and in the vagina has been used for long and has proven to be beneficial in the treatment of patients with gynecologic malignancies that it is considered a standard procedure. The tolerance of the mucosa in this region is very high that permits curative doses often in excess of 10000 rad to be delivered. Anatomically, this region lends itself to intracavitary placement of radioactive sources. In other anatomical regions where there is no body cavity, it is necessary to place the radioactivity directly into the tumor. This treatment is referred to as interstitial. Treatment of diffuse intraperitoneal or intrapleural disease is sometimes attempted through the deposition of radioactive fluids into the peritoneal or pleural cavity. Radioactive substances used for interstitial treatment are usually encapsulated in a shield shaped as a needle and usually contain Ra-226. Different types of brachytherapy treatments require different isotopes in several different physical states—solids or solutions—in a variety of carriers.