Modern diagnostic medicine has benefited significantly from radiology. Radiation, such as x-rays, may be used to generate images of internal body structures. In general, radiation is emanated towards a patient's body and absorbed in varying amounts by tissues in the body. An x-ray image is then created based on the relative differences of detected radiation passing through the patients' body.
Digital subtraction is a well known technique for visually enhancing differences between such images. For example, digital subtraction angiography (DSA) is used to visualize vasculature by comparing two or more images of the same blood vessels before and after injection of a contrast agent. Assuming that the only change between the pre-contrast image (or “mask”) and the contrast-containing image is related to the injection of the contrast agent, the “difference image” clearly outlines the vessels into which the contrast agent has flowed.
However, digital subtraction techniques assume a fixed relative position between the imaging device and the patient being imaged for any images which are being compared. If this relative position changes between the time that the initial image (the one to which all subsequent images are compared) is acquired and the time that any of the subsequent images are acquired, the difference image will not only convey changes in the anatomy of the patient, but also any “artifacts” or changes introduced by this change in relative position between the imaging device and the patient.
Therefore, it is desirable to provide a medical imaging system that addresses the patient motion artifact problem. It is envisioned that the system will directly measure the relative position between the imaging device and the patient, and then compensate the images for any motion that occurs between the time at which the initial image is acquired and the time at which any subsequent images are acquired by the imaging system.