1. An image-guided radiation therapy system for treating a target within a patient, the system comprising: a treatment delivery system having a radiation source configured to generate treatment radiation beams and a collimator configured to collimate the treatment radiation beams; a multi-energy imaging system configured to generate a first set of image data of part or all of the patient using first imaging radiation at a first energy level and a second set of image data of part or all of the patient using second imaging radiation at a second energy level, wherein the multi-energy imaging system comprises: a first x-ray source configured to emit the first imaging radiation at the first energy level towards part or all of the patient, and a first x-ray detector configured to receive the first imaging radiation at the first energy level after at least a first portion of the first imaging radiation has passed through part or all of the patient, wherein the first energy level is a lower energy level relative to the second energy level; and a second x-ray source configured to emit the second imaging radiation, at part or all of the patient and a second x-ray detector configured to receive the second imaging radiation after at least a second portion of the second imaging radiation has passed through part or all of the patient, wherein the second energy level is a higher energy level relative to the first energy level; wherein the first and second x-ray sources are configured to substantially simultaneously emit the first and second imaging radiations, respectively; and a system processor configured to process the first and second sets of image data to generate an enhanced image of part or all of the patient, wherein the enhanced image comprises a combination of the first and second sets of image data, the system processor further configured to direct the treatment delivery system based on information obtained from the enhanced image, wherein part or all of the image data comprises the target; and wherein the system processor is configured to track movement and position of the target using a motion-edge artifact in the enhanced image.