Brachytherapy for pediatric central nervous system tumors
Stem Cell Transplantation
Sixteen patients have undergone interstitial implantation with high activity 125Iodine sources (20-40 mCi) in sufficient numbers to deliver approximately 1000 rad/day (30-50 rad/hr) to the tumor periphery. Implantation of high activity 125I sources was performed using CT guided stereotaxy under general anesthesia in children. Adolescents were cooperative enough to be implanted under local anesthesia. The Brown-Roberts-Wells (BRW) CT stereotaxic system was used for implantation. Patients were treated at recurrence or as an adjuvant boost to focal external beam radiation therapy. There was no perioperative morbidity or mortality from the implantation proceure. Patients who underwent permanent implantation of low activity 125I sources all succumbed to their tumors. The results of high activity 125I implantation were more encouraging. At present, radiation therapy remains the most effective treatment for central nervous system tumors in children and brachytherapy is an attractive alternative to conventional external beam radiation therapy. The recent development of a computer program to plan the treatment and calculate the BRW system coordinates has facilitated our accuracy and dosimetry. Based on our experience in children and adults we feel that brachytherapy either alone or in combination with other treatment modalities will become the treatment of choice for selected tumors in children and adolescents.