IMRT FOR CRANIOSPINAL IRRADIATION: CHALLENGES AND RESULTS

To develop, investigate and implement IMRT method for Craniospinal irradiation (CSI) into the clinical environment. The study was performed for patients required either CSI or only extracranial (spinal) irradiation. IMRT plans with multiple isocenters without couch rotation and with overlap of field edges as well as standard technique 3D CRT plan were generated for each patient. The planning dose distributions for both methods and effect of patient set up uncertainties were investigated. As expected the IMRT treatment plans provided much better dose coverage and homogeneity in the target volume. Treatment verification proved, that interfractional movement of the field isocenters relative to the patient anatomy was within 3 mm limits in all cases. The IMRT plans provide much better dose distribution stability for these movements in comparison with 3DCRT plans. Dose bath in the dose range over 10 Gy within the "cancerous" distance from the fields' edges was significantly lower for all IMRT plans created. The developed IMRT method for CSI and spinal irradiation provides superior dose coverage throughout the target volume, simplifies the technical performance, is less dependent on intrafractional movements of the patient and potentially reduce the risk of deterministic secondary cancer incidence. This method is recommended for use in the clinic for all CSI patients.