Motion-compensated 4D cone-beam computed tomography

In image-guided radiation therapy (IGRT) beside the linear particle accelerator an additional kV system provides information for an accurate patient positioning. The precise execution of the treatment plan is assured that way. An extra goal is the refinement of further planned treatment fractions based on the on-board imaging system information. Additional inter-fractional planning CTs become thus obsolete. However, the acquisition time of the system is much longer than the patient's breathing cycle due to technical limitations on the gantry rotation speed. Severe artifacts like blurring or streaks are the consequence. They affect image quality and thus also the refinement of the treatment plan.