Computer-implemented method for ascertaining an item of torsion information of a bone, x-ray facility, computer program and electronically readable data carrier

An X-ray facility with adjustable projection geometry of a recording arrangement described by projection parameters, the X-ray facility comprising:

• an X-ray source;
• and
• an X-ray detector, the X-ray detector comprising a control facility configured to:
• record a first X-ray image of an end region of a bone in a first projection geometry in which a torsion direction defined relative to at least one torsion landmark and used for ascertaining a roll angle lies in a first computing plane, which is formed by a focal point of the X-ray source and a reference direction that is determined in the first X-ray image by at least one reference landmark;
• record a second X-ray image of the end region of the bone in a second projection geometry with a direction of projection deviating from the direction of projection of the first projection geometry and forming a second computing plane from the reference direction that is determined in the second X-ray image by the at least one reference landmark, and the focal point;
• and
• ascertain a three-dimensional course of the reference direction and the torsion direction from the first computing plane, the second computing plane, and the roll angle as a rotation of the torsion direction about the reference direction with respect to a comparison specification;
• wherein an item of torsion information is ascertained from the roll angle.

A non-transitory computer readable storage medium comprising a set of computer-readable instructions stored thereon for ascertaining an item of torsion information of a bone, of a patient, wherein an X-ray facility with adjustable projection geometry of a recording arrangement described by projection parameters is used, the X-ray facility comprising an X-ray source and an X-ray detector, the instructions which, when executed by at least one processor cause the processor to:

• record a first X-ray image of an end region of the bone in a first projection geometry in which a torsion direction defined relative to at least one torsion landmark and used for ascertaining a roll angle lies in a first computing plane, which is formed by a focal point of the X-ray source and a reference direction that is determined in the first X-ray image by at least one reference landmark;
• record a second X-ray image of the end region of the bone in a second projection geometry with a direction of projection deviating from the direction of projection of the first projection geometry and forming a second computing plane from the reference direction that is determined in the second X-ray image by the at least one reference landmark, and the focal point;
• and
• ascertain a three-dimensional course of the reference direction and the torsion direction from the first computing plane, the second computing plane, and the roll angle as a rotation of the torsion direction about the reference direction with respect to a comparison specification;
• wherein the item of torsion information is ascertained from the roll angle.