Abstract: Devices, systems and methods for radiation treatment are disclosed herein. The device may include a light gathering element having an outer surface, a portion of the outer surface of the light gathering element being substantially omni-directional. A portion of the outer surface of light gathering element is coupled to an optical fiber at substantially the base of the optical fiber. The device may include a cartridge having an opening therein for receiving the optical fiber, the light gathering element positioned at an end of the cartridge. A detector, coupled with the optical fiber, may be in the cartridge.