Methods and system for facilitating rapid radiation treatments are provided herein and relate in particular to radiation generation and delivery, electron source design, beam control and shaping/intensity-modulation. The methods and systems described herein are particularly advantageous when used with a compact high-gradient, very high energy electron (VHEE) accelerator and delivery system (and related processes) capable of treating patients from multiple beam directions with great speed, using all-electromagnetic or radiofrequency deflection steering is provided; or when used with a high-current electron accelerator system of energy range more conventionally used in photon radiation therapy to produce much faster delivery of intensity-modulated photon radiation therapy, that can in both cases deliver an entire dose or fraction of high-dose radiation therapy sufficiently fast to freeze physiologic motion, yet with a equal or better degree of dose conformity or sculpting compared to conventional photon therapy.