Volumetric Modulated Arc Therapy Craniospinal Re-Irradiation of Adulthood Medulloblastoma Leptomeningeal Disease

Abstract

For the first time in the English medical literature we present two adulthood clinical cases with medulloblastoma leptomeningeal disease (LMD) in which we have performed second craniospinal irradiation (re-CSI) using bias volumetric-modulated arc therapy (VMAT) technique. In this article we present bias volumetric-modulated arc therapy (VMAT) technique for repeated CSI (re-CSI) in two patients with adulthood medulloblastoma leptomeningeal disease (LMD). In both clinical cases (case1/case2) with adulthood medulloblastoma LMD, re-CSI has been performed using the bias VMAT technique in the area of the spinal cord up to total dose (TD) - 24 Gy/32 Gy; cauda equina up to TD- 28 Gy/38 Gy; in the cerebellum up to TD- 24 Gy/28 Gy; both cerebral hemispheres up to TD- 26 Gy/32 Gy and the cerebral ventricles up to TD-30 Gy/38 Gy with daily dose (DD)-1.8 Gy (17/21fractions). We describe in detail the stages of dosimetry planning of this radiotherapy technique, presenting its advantages and disadvantages, the observed early radiation toxicity and the possible treatment outcome. Volumetric-modulated radiotherapy with bias dose VMAT technique in adulthood medulloblastoma patients achieves improved dose homogeneity at the junction of the fields, increased compliance with the target volume and minimized dose to the organs at risk (OARs).