X-ray ring markers for x-ray calibration

A C-arm registration controller for registering a C-arm to a X-ray ring marker, the X-ray ring marker including a coaxial construction of a chirp ring and a centric ring on an annular base, the C-arm registration controller comprising:

• a non-transitory machine-readable storage medium encoded with instructions for execution by at least one processor of a registration of the C-arm to X-ray ring marker, the non-transitory machine-readable storage medium comprising instructions to:
• acquire a baseline X-ray image illustrative of the X-ray ring marker within a baseline X-ray projection by the C-marker at a baseline imaging pose;
• derive baseline position parameters of the X-ray ring marker as a function of an illustration of the centric ring within the baseline X-ray image, the baseline position parameters being definitive of a position of the X-ray ring marker within the baseline X-ray projection;
• and
• derive a baseline twist parameter of the X-ray ring marker as a function of the baseline position parameters and of an illustration of the chirp ring within the baseline X-ray image, the baseline twist parameter being definitive of a twist of the X-ray ring marker within the baseline X-ray projection.

A C-arm registration method executable by a C-arm registration controller for registering a C-arm to a X-ray ring marker, the X-ray ring marker including a coaxial construction of a chirp ring and a centric ring on an annular base, the C-arm registration method comprising:

• acquiring, via the C-arm registration controller, a baseline X-ray image illustrative of the X-ray ring marker within a baseline X-ray projection by the C-arm at a baseline imaging pose;
• deriving, via the C-arm registration controller, baseline position parameters of the X-ray ring marker as a function of an illustration of the centric ring within the baseline X-ray image, the baseline position parameters being definitive of a position of the X-ray ring marker within the baseline X-ray projection;
• and
• deriving, via the C-arm registration controller, a baseline twist parameter definitive of the X-ray ring marker as a function of the baseline position parameters and of an illustration of the chirp ring within the baseline X-ray image, the baseline twist parameter being definitive of a twist of the X-ray ring marker within the baseline X-ray projection.