Technical Review of Target Volume Delineation on the Posterior Fossa Tumor:An Optimal Head and Neck Position / 대한방사선종양학회지

ABSTRACT

PURPOSE: To explore a 3D conformal radiotherapy technique for a posterior fossa boost, and the potential advantages of a prone position for such radiotherapy. MATERIALS AND METHODS: A CT simulator and 3D conformal radiotherapy planning system was used for the posterior fossa boost treatment of a 13-year-old medulloblastoma patient. He was placed in the prone position and immobilized with an aquaplast mask and immobilization mold. CT scans were obtained of the brain from the top of the skull to the lower neck, with IV contrast enhancement. The target volume and normal structures were delineated on each slice, with treatment planning performed using non-coplanar conformal beams. RESULTS: The CT scans, and treatment in the prone position, were performed successfully. In the prone position, the definition of the target volume was made easier due to the well enhanced tentorium. In addition, the posterior fossa was located anteriorly, and with the greater choice of beam arrangements, more accurate treatment planning was possible as the primary beams were not obstructed by the treatment table. CONCLUSION: A posterior fossa boost, in the prone position, is feasible in cooperating patients, but further evaluation is needed to define the optimal and most comfortable treatment positions.