Tratamiento del meduloblastoma: comparación entre arcoterapia volumétrica modulada y radioterapia conformada tridimensional

Abstract

Objective: To present the feasibility of the treatment of medulloblastoma with volumetric-modulated arc therapy (VMAT) planned with RayStation for Elekta linacs and compare the results with conventional treatment. \nMaterials and methods: 3 adult patients in prone position treated with 3D-conformal radiotherapy (3DCRT) with 6 MV and 18 MV were replanned with 6 MV VMAT. The dose prescription was 1.8 Gy/fraction. The evaluation of the techniques was carried out with dose-volume histograms and isodoses in target volumes and healthy tissues, and with conformity (CI) and homogeneity (HI) indexes. \nResults: VMAT CI (0.79\u202f±\u202f0.02) and HI (0.08\u202f±\u202f0.02) of the tended to be better than those of 3DCRT (CI\u202f=\u202f0.58\u202f±\u202f0.03 and HI\u202f=\u202f0.14\u202f±\u202f0.07). For healthy tissues, a decrease in the maximum absorbed dose was observed (VMAT: D1%\u202f=\u202f1.76\u202f±\u202f0.04 Gy/fraction and 3DCRT: D1%\u202f=\u202f1.93\u202f±\u202f0.04 Gy/fraction) as well as in the overdoses (VMAT: V107%\u202f=\u202f0.05\u202f±\u202f0.08% and 3DCRT: V107%\u202f=\u202f1.0\u202f±\u202f0.5%). The dosimetric results of organs at risk showed no trend when both techniques were compared. \nConclusion: The performance with RayStation of the medulloblastoma treatment by VMAT is viable for Elekta linacs, and a greater coverage, homogeneity and conformation in the target is achieved. Overdoses were also markedly reduced compared with those caused by 3DCRT treatments.