Displacement of the rectum and bladder are pivotal in reducing risk to these organs. As always, the challenge is to obtain an appropriate radiation dose distribution within the volume at risk while keeping the dose to surrounding normal structures at a minimum. Though radium is a familiar term to many physicians, radium is no longer used in the treatment of cervical carcinoma. The radioisotope cesium 137 is utilized at many institutions. HDR brachytherapy necessarily entails short, but multiple applications and is delivered on an outpatient basis.
Fractionation is essential, as is dose modification to decrease complications.
Both LDR and HDR techniques exploit afterloading. With this, an ideal implant pattern is established with the applicators, prior to loading of radioactive sources. This sequence ensures accuracy and reduces radiation exposure to medical personnel. With remote afterloading, the radioactive sources are housed in a computerized, shielded control until remote from the patient, and advanced and retracted upon demand without the need for human handling. A single source is required, which moves through the applicator in step increments, dwelling in selective positions for an appropriate time determined through computerized dosimetry generation and analysis.