Exact patient positioning by compairing reconstructed x-ray images and linac x-ray images

A method for exact positioning of a patient for radiotherapy or radiotherapy comprising the steps:

• a) pre-positioning the patient relative to a linear accelerator,
• b) producing at least one X-ray image of the patient or one of his/her body parts in the vicinity of the radiation treatment target,
• c) mapping said X-ray image,
• d) generating at least one reconstructed image from a three-dimensional set of patient scanning data corresponding to said X-ray image,
• e) superimposing said reconstructed image and said X-ray image, and detecting the positional error electronically or computer-controlled on the basis of special landmarks in both images, and
• f) correcting the position of the patient on the basis of the detected positional error, and
• wherein pre-positioning is carried out by means of a computer-controlled and camera-controlled navigation and tracking system with the aid of artificial marker arrangements on the patient and on the treatment devices.