We report on a radiation treatment technique that has reduced the dose to critical normal structures in children with medulloblastoma.
Three children between the ages of 3 and 4 with stage M2 or M3 medulloblastoma were treated between 2001 and 2003 with craniospinal irradiation using protons. Patients received 36 cobalt gray equivalent to the craniospinal axis, then 18 cobalt gray equivalent to the posterior fossa. The cranium was treated with opposed lateral fields. The spine was treated with three matched posteroanterior fields, with the beam stopping just beyond the thecal sac. The posterior fossa was then treated with alternating posteroanterior, right posterior oblique, and left posterior oblique fields, with the beam stopping just proximal to the cochlea. The use of general anesthesia and pre-porting with diagnostic-quality x-rays allowed precise patient positioning.
Craniospinal irradiation delivered via conformal proton irradiation substantially reduced the dose to the cochlea and vertebral bodies and virtually eliminated the exit dose through thorax, abdomen, and pelvis. Despite concurrent chemotherapy, a clinically significant lymphocyte count reduction was not seen. Patients tolerated treatment well; acute side effects (e.g., nausea, decreased appetite, and odynophagia) were mild. All patients completed therapy without interruption.
Our proton-beam technique for craniospinal irradiation of pediatric medulloblastoma has successfully reduced normal-tissue doses and acute treatment-related sequelae. This technique may be especially advantageous in children with a history of myelosuppression, who might not otherwise tolerate irradiation.
Department of Radiation Medicine, Loma Linda University Medical Center, Loma Linda, California.
Reprint requests: Jerry D. Slater, MD, Department of Radiation Medicine, Loma Linda University Medical Center, 11234 Anderson Street Suite B-121, Loma Linda, CA 92354. E-mail: firstname.lastname@example.org.
No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this article.
Presented at the 86th Annual Meeting for the American Radium Society in Napa Valley, CA on May 1–5, 2004.
Received on September 22, 2004; accepted for publication October 13, 2004.