1. Field of the Invention
The present invention relates to an X-ray diagnostic apparatus which displays a road map representing a blood vessel structure.
2. Description of the Related Art
In intervention or angiographic examination, a catheter is inserted into a blood vessel from, for example, the joint of a leg and is brought to a target region through the blood vessel. This catheter or a guide wire inserted in the catheter is moved forward to a target position under fluoroscopic observation of an X-ray image. However, the blood vessel cannot be seen in an X-ray image unless enhanced by a contrast medium. Keeping injecting the contrast medium to visualize the blood vessel may result in renal failure. For this reason, there is available a function of holding an X-ray image of a blood vessel obtained by radiography after a contrast medium is injected once as a two-dimensional road map, and displaying the image upon superimposing it on an X-ray fluoroscopic image obtained in real time. This function allows the operator to discriminate the position of a blood vessel to a certain extent without injecting any contrast medium, and hence is often used especially when a blood vessel structure is complicated and it is difficult to push a catheter or a guide wire into the blood vessel.
When, however, a road map is converted into a three-dimensional image, a portion other than the catheter or guide wire, e.g., a bone, is imaged. This makes it very difficult to see the image of the catheter or guide wire.