Palliative Spatially Fractionated (GRID) Radiotherapy Using Intensity Modulated Proton Therapy

The proton GRID radiotherapy prescription dose is 20 Gy x 3 fractions to the tumor, with an integrated dose of 6 Gy x 3 fractions to the PTV. Treatment to multiple lesions within the PTV is allowed (ex. a dominant lesion plus satellites). Multiple proton GRID radiotherapy plans may be delivered on the same day or different days, but they cannot overlap.