Are moving junctions in craniospinal irradiation for medulloblastoma really necessary?

The case notes of 35 patients treated for medulloblastoma using a standard technique of craniospinal irradiation (CSI) from 1978 to 1992 were reviewed. Two large opposed lateral fields to the whole brain and an orthogonal posterior spinal field were used. The position of the junction between the fields was constant throughout treatment with no feathering and no gap. We present our results, review the literature and discuss the need for feathering. The junction between the cranial and spinal fields produces an area of dose inhomogeneity but the clinical significance of this and the effect of feathering is uncertain.