Fixtures for fluoroscopic imaging systems and related navigation systems and methods

A fixture for a fluoroscopic x-ray imaging system, wherein the fluoroscopic x-ray imaging system includes a C-arm, an x-ray source at a first end of the C-arm, and an x-ray detector at a second end of the C-arm, the fixture comprising:

• a processor;
• and
• memory coupled with the processor, wherein the memory includes instructions that are executable by the processor so that the fixture is configured to,
• detect an x-ray emission from the x-ray source toward the x-ray detector,
• determine an offset of the x-ray source relative to the x-ray detector, responsive to detecting the x-ray emission, and
• provide an indication of the offset of the x-ray source to a medical navigation system.

A fixture for a fluoroscopic x-ray imaging system, wherein the fluoroscopic x-ray imaging system includes a C-arm, an x-ray source at a first end of the C-arm, and an x-ray detector at a second end of the C-arm, the fixture comprising:

• an x-ray opaque fiducial pattern in a single plane, wherein the fixture is coupled with the x-ray detector so that the x-ray opaque fiducial pattern is on a surface of the x-ray detector between the x-ray detector and the x-ray emitter,
• wherein a medical navigation system configured to receive a first patient image from the fluoroscopic imaging system corresponding to a first orientation of the C-arm with the first patient image including first shadows corresponding to the x-ray opaque fiducial pattern, to receive a second patient image from the fluoroscopic imaging system corresponding to a second orientation of the C-arm with the second patient image including second shadows corresponding to the x-ray opaque fiducial pattern, and to provide a registration between a tracking coordinate system for a physical space monitored by tracking cameras and an image coordinate system for the first patient image and the second patient image based on a correlation of offsets of the x-ray source relative to the x-ray detector relative to the x-ray detector as a function of an orientation of the x-ray detector relative to gravity and based on the first shadows in the first patient image and the second shadows in the second patient image.