Cranio-spinal irradiation with volumetric modulated arc therapy: A multi-institutional treatment experience

Purpose: To report the treatment of cranio-spinal irradiation (CSI) with volumetric modulated arc therapy (RapidArc) in adults and a child. Materials and methods: Five patients from 5 institutions were treated with CSI using RapidArc technology. Patient age varied between 7 and 45 years. The lengths of the planning target volumes (PTV) and dose prescriptions ranged from 54.6 to 78.4 cm, and from 12 to 36 Gy, respectively. Different arc arrangements were used, with two or three isocentres, from two to six modulated arcs, for patient positioned either in prone (n = 3) or supine position (n = 2). Doses to PTV, organs at risk and non-target tissue are reported for each of the five patients. Data concerning imaging strategy and pre-treatment quality assurance are also reported. Results: The mean conformity index CI95% was 1.05 ± 0.05 (range: 1.00, 1.13). Mean doses to the lenses, lungs, heart, and kidneys were, respectively, 7.6 ± 1.6, 6.6 ± 3.0, 5.7 ± 2.3, and 6.1 ± 2.1 Gy, keeping those value acceptably low. Mean non-target tissue dose was 21.0 ± 3.8% (5.6 ± 1.8 Gy, range: 3.0–8.1 Gy). All patients were successfully planned and treated with RapidArc. Conclusions: RapidArc techniques achieved highly conformal treatment plans for 5 adults or paediatric patients. Beam-on time was short, and RapidArc plans were satisfactorily delivered to all presented patients.