Abstract: Systems and methods of controlling the leaves of an aperture in radiation treatment are disclosed. In some embodiments, these systems and methods allow the delivery of different radiation fluences to different parts of a treatment volume in a single rotation of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by radiating different parts of the treatment volume from opposing positions of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by assigning different leaf pairs to radiate different parts of the treatment volume.

Abstract: The present invention provides an intensity modulated radiation therapy (IMRT) method for treating a target region that minimizes the tongue and groove effect. By minimizing that effect, striping in the final delivered fluence is reduced, which improves the overall quality of the radiation delivery. In the method, compensating functions Ci(x) are added to leaf coordinates ai(x) and bi(x) for all of the leaf pairs i in a leaf sequence algorithm, where Ci(x) is chosen to match the mechanical limitations of the MLC and to minimize non-weighted or weighted sums of the tongue and groove effects, where the weighting is time-dependent, position-dependent, or time- and position-dependent, or to minimize the total treatment time, changes to the original MLC sequence, or the tongue and groove effect distribution variance in spatial or temporal coordinates.

Abstract: Systems and methods of controlling the leaves of an aperture in radiation treatment are disclosed. In some embodiments, these systems and methods allow the delivery of different radiation fluences to different parts of a treatment volume in a single rotation of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by radiating different parts of the treatment volume from opposing positions of the aperture around the treatment volume. In some embodiments, different radiation fluences are achieved by assigning different leaf pairs to radiate different parts of the treatment volume.

Abstract: A system for use to determine or evaluate a radiation treatment plan includes a processor configured for determining a spatially variable constraint, and imposing the spatially variable constraint on a healthy tissue. A system for use to determine or evaluate a radiation treatment plan includes a processor configured for determining a first position of a first healthy tissue, imposing a first constraint on the first healthy tissue based on the determined first position, determining a second position of a second healthy tissue, and imposing a second constraint on the second healthy tissue based on the determined second position, wherein the first constraint and the second constraint have different values. A radiation system includes a processor configured for determining a treatment plan using a spatially variable constraint on healthy tissue, and a radiation machine for performing a radiation procedure based on the determined treatment plan.