Abstract: Radiotherapy controlling, treatment sinograms may be directly modified to correct for real time motion of patients or portions of patients resulting from physiological or other activity. Precalculated partial sinograms representing treatments of portions of a patient may be assembled to obtain a treatment sinogram for the entire patient without delay from conventional planning software. The partial sinograms are modified as representations of their corresponding portions and manipulated to conform to the particular dimensions of an actual patient. This constructed sinogram may be used directly or as a starting point for iterative optimization.

Abstract: A method of calibration and verification of radiotherapy systems deduced radiation beam fluence profiles from the radiation source from a complete model of an extended radiation phantom together with dose information from a portal imaging device. The improved beam fluence profile characterization made with an iterative modeling which includes scatter effects may be used to compute dose profiles in the extended phantom or a patient who has been previously characterized with a CT scan. Deviations from the expected beam fluence profile can be used to detect patient misregistration.

Abstract: A method for aligning a patient for radiation treatment based on an earlier tomographic scan of the patient uses projection images used to reconstruct a tomographic image rather than reconstructed images and compares the projection images directly to projection images taken at the time of the radiation therapy to determine a series of offsets of the patient which may be used to characterize and correct for motion of the patient between the initial tomographic scan, used for treatment planning, and one or a series of subsequent radiation treatment sessions.

Abstract: A radiation therapy apparatus includes a collimator that changes the width of a fan beam of radiation as a treatment volume of the patient crosses the volume exposed by the beam so as to minimize the irradiation of healthy tissue at the front and back of the tumor. The width of the fan beam may also be controlled to treat multiple adjacent, similar slices of the patient at one time reducing the treatment duration.