Dose distributions of high-precision radiotherapy treatment: A comparison between the CyberKnife and TrueBeam systems

Background: several high-precision stereotactic radiation therapy modalities arecurrently used in clinical settings. we aimed to evaluate whether the cyberknife(ck) or truebeam (tb) radiation treatment systems were more appropriate fortreating targets of various morphologies according to the physical properties ofeach device. materials and methods: spheres (diameter = 5–50 mm), as well astriangular prisms and cubes (length of a side = 10–50 mm), were used as virtualtargets for each treatment delivery system. a phantom with dosimetry film wasirradiated to evaluate the flatness and gradient of the radiation treatment fromeach modality. results: the homogeneity index (hi) for the spherical targetswas significantly higher (dose distribution was more homogeneous) using thetb than when using the ck (1.9 vs. 1.4; p = 0.002). there were no significantdifferences between treatment modalities in the hi for more complex shapes.the hi increased monotonically as the virtual target diameter increased forthe ck (p = 0.048). the flatness parameter was lower for the tb than for theck (1.4 vs. 1.1; p < 0.001). conclusion: the ck is particularly robust for deliveringtherapeutic radiation to small targets, while the tb is more suitable for targets witha simple shape or when the hi is a critical treatment factor.