Interstitial Brachytherapy in Gynaecological Cancer

Interstitial brachytherapy is generally reserved for patients either with extensive pelvic and/or vaginal disease in an attempt to improve local control or with anatomy not allowing intracavitary brachytherapy with standard applicators. The aim of this technique is to tailor the dose of irradiation to the anatomy of the patient with a better target volume coverage. The technique was initially developed using radium 226 (1,2) (Fig 17.1) or cobalt 60 (3) needles. Originally, interstitial implants were performed with free-hand placement of the radioactive needles (4). The development of transperineal (5,6,7,8,9,10) or transvaginal (11,12) templates resulted in a better needle positioning. Newer techniques including fluoroscopy (13), computed tomography (14), transabdominal or transrectal ultrasound (15), magnetic resonance imaging (16), laparoscopy (17), and laparotomy (18) have improved the needle placement accuracy. Radioactive material consists of Iodine-125 seeds employed as permanent implants (19) or more generally Iridium-192 seeds or wires sources employed as temporary implants with either low dose rate or high dose rate. Despite an improvement in the technological approach of these techniques, the potential benefit of interstitial brachytherapy in gynecological malignancies has not been clearly demonstrated. This technique is associated with a potential increase in the risk of complications.