ABSTRACT
Background: several high-precision stereotactic radiation therapy modalities are currently used in clinical settings. We aimed to evaluate whether the CyberKnife [CK] or TrueBeam [TB] radiation treatment systems were more appropriate for treating targets of various morphologies according to the physical properties of each device
Materials and Methods: spheres [diameter = 5-50 mm], as well as triangular prisms and cubes [length of a side = 10-50 mm], were used as virtual targets for each treatment delivery system. A phantom with dosimetry film was irradiated to evaluate the flatness and gradient of the radiation treatment from each modality
Results: the homogeneity index [HI] for the spherical targets was significantly higher [dose distribution was more homogeneous] using the TB than when using the CK [1.9 vs. 1.4; p = 0.002]. There were no significant differences between treatment modalities in the HI for more complex shapes. The HI increased monotonically as the virtual target diameter increased for the CK [p = 0.048]. The flatness parameter was lower for the TB than for the CK [1.4 vs. 1.1; p < 0.001]
Conclusion: the CK is particularly robust for delivering therapeutic radiation to small targets, while the TB is more suitable for targets with a simple shape or when the HI is a critical treatment factor