Brachytherapy — head and neck cancer

Abstract

Interstitial implantation of radioactive sources, brachytherapy, is frequently used in the treatment of head and neck cancers. Implanting radioactive isotopes is a means of not only obtaining high localized radiation doses to the tumor bed, but also minimizing normal tissue injury, since the radiation is delivered only to the area of neoplastic involvement. Brachytherapy has been practiced for many years; 226-Radium needles or 222-Radon sources were used initially [1], but it was not until the last decade that interstitial implants have become more popular, due to several factors. The availability of new isotopes, such as 125-Iodine (¹²⁵I) for permanent implantation and 192-Iridium (¹⁹²Ir) for removable procedures, has allowed more complex interstitial procedures to be performed, while the latter isotope, by making afterloading possible, has minimized radiation doses to medical personnel [2–4]. Computerized dosimetry has enabled implants to be pre-planned, so that ideal symmetry and proper placement of sources may be determined prior to the procedure, while post-implantation dosimetry not only allows radiation dose rates to be calculated with removable implants, but also provides a method of correlating results and complications with radiation doses [5]. New implant techniques, to be discussed, have also contributed to our ability to perform these procedures effectively and safely. In this chapter, the common radioactive isotopes in use today will be described, as will the techniques of implantation and the results of treatment of selected primary sites and cervical lymph nodes.