Radiation treatment methods comprise: obtaining initial image data of a region of interest initially optimizing one or more radiation delivery variables of a radiation treatment plan based on the initial image data and dividing the plan into one or more fractional treatments. Each fractional treatment comprises: delivering an initial portion of a fraction based on the one or more initially optimized radiation delivery variables obtaining fractional image data pertaining to the region of interest fractionally optimizing the one or more radiation delivery variables based at least in part on the fractional image data and delivering a subsequent portion of the fraction based on the one or more fractionally optimized radiation delivery variables. At least part of delivering the initial portion of the fraction overlaps temporally with at least one of: obtaining the fractional image data and fractionally optimizing the one or more radiation delivery variables.
