Comparison of VMAT craniospinal treatment delivery between Halcyon and Varian Clinac iX

Abstract

Meduloblastomas are pediatric tumors that require irradiation of the entire craniospinal axis (CSI) which can be up to 80 cm in length for older pediatric patients. This presents some unique challenges in the treatment planning and radiotherapy delivery for these cases. Traditionally, in the classical 3D conformal radiotherapy with uniform intensity, this was solved by moving the junction of the adjacent fields so that the cold and hot parts of the target volume were not at the same place in the successive daily fractions [1]. As the technology evolved, new methods became available with modulated field intensities, which eliminated the need to move the field junctions [2]. Finally, with the introduction and development of the O-ring linac technology, which increased the speed and accuracy of the delivery, additional irradiation options became available for the CSI [3, 4]. In this work we evaluated the CSI on two different radiotherapy units at the University Clinic for Radiotherapy and Oncology in Skopje, a new Halcyion unit and an older Clinac iX, from a practical aspect of reducing the overall time the patient lies on the treatment couch during daily treatment, while maintaining the same quality of treatment plan and delivery.