[Whole brain radiotherapy for brain metastases: the technique of irradiation influences the dose to parotid glands]

Abstract

In the treatment of brain metastases, whole brain radiotherapy can be carried out according two distinct methods: one using multileaf collimator for field shaping and protection of organs at risk, and a second one is to make a rotation of the field to avoid the eyes. The aim of the study was to compare for 10 patients the dose distributions at organs at risk for each method. Patients received 30 Gy in 10 fractions. Except for parotid glands, the dose received by organs at risk and the planning target volume was the same with each method. For whole brain radiotherapy, excluding the cisterna cerebellomedullaris, the mean parotid dose was 9.63 Gy using the multileaf collimator versus 12.32 Gy using the field rotation (P=0.04). For whole brain radiotherapy including the cisterna cerebellomedullaris, the mean parotid dose was 11.12 Gy using the multileaf collimator versus 20.06 Gy using field rotation (P<0.001). Using the multileaf collimator seems recommended for whole brain radiotherapy, to reduce the dose to the parotids.