Method and device for determining a position of a part of a medical instrument

A method for determining a position of a part of a medical instrument provided with an x-ray sensitive sensor in a plane of an x-ray image using an x-ray device, comprising:

• mechanically scanning by way of a shutter a spatial region in which the medical instrument provided with the x-ray sensitive sensor is located by x-ray radiation emitted from an x-ray beam source of the x-ray device;
• arranging an x-ray beam detector opposite and spaced-apart from the x-ray beam source, wherein the medical instrument with the x-ray sensitive sensor is interposed between the x-ray beam source and the x-ray beam detector;
• while x-ray radiation is emitted by the x-ray beam source, rotating at a constant speed the shutter which is coupled to the x-ray beam source for influencing the x-ray radiation emitted by the x-ray beam source, the shutter having a central axis and wherein said rotating is performed about the central axis of the shutter;
• detecting the x-ray radiation by the x-ray sensitive sensor;
• synchronizing the rotation of the shutter to the detection of the x-ray radiation by the x-ray sensitive sensor;
• automatically determining the position of the part of the medical instrument in the plane of the x-ray image based on the following:
• φ
• =
• t
• 1
• -
• t
• 0
• τ
• ·
• 2
• ⁢
• π
• ,
• where φ represents an angle of tip of the medical instrument in the plane of the x-ray image, t0 represents an initial time regarding a constant rotation of the shutter, t1 represents a time at which x-ray radiation is detected by the x-ray sensitive sensor, and τ represents a period of the constant rotation of the shutter;
• R
• =
• c
• a
• ·
• r
• ,
• wherein R represents radius of the tip of the medical instrument in the plane of the x-ray image, r represents radius on the shutter of the x-ray beam striking the x-ray sensitive sensor, c represents a distance from a focal point of the-ray beam to the x-ray beam detector, and a represents a distance from the focal point of the-ray beam to the shutter;
• and
• wherein the medical instrument is inserted into a body of a patient;
• and
• overlaying the position of the tip of the medical instrument on the x-ray image for assisting navigation of the medical instrument without registration even if the medical instrument and the x-ray sensitive sensor can not be seen or is difficult to be seen in the x-ray image because of material selection or miniaturization of the medical instrument.