Tracking system for imaging machines and related apparatus

A method for monitoring changes in pose of a C-arm X-ray imaging apparatus comprising a mobile cart, a gantry arm coupled to the cart by a mechanical linkage comprising a plurality of movable mechanical joints and a radiation source and an imaging radiation detector carried by the gantry arm, the method comprising:

• removably affixing surface-mounted sensors to the X-ray imaging apparatus, each of the sensors operable to sense positions of a corresponding one or more of the mechanical joints;
• by a control system comprising a data processor connected to receive the output signals from the sensors:
• performing a sensor registration procedure and a joint registration procedure and from results of the sensor registration procedure and the joint registration procedure generating transformation matrices that relate outputs of the sensors to positions of the gantry arm relative to the mobile cart according to a kinematic model of the C-arm X-ray imaging apparatus;
• the sensor registration procedure determining relationships between coordinate systems of the sensors and a fixed coordinate system fixed relative to a body segment of the C-arm X-ray machine, the sensor registration procedure comprising, for each of a plurality of different configurations of the C-arm X-ray imaging apparatus, the different configurations differing from one another by positions of one or more of the mechanical joints, obtaining readings from the sensors when the C-arm X-ray imaging apparatus is in each of the different configurations and processing the sensor readings to obtain sensor registration information indicative of the relationship between the coordinate systems of the sensors and the fixed coordinate system;
• the joint system calibration procedure yielding joint calibration information specifying the kinematic model of the C-arm X-ray imaging apparatus, the joint system calibration procedure comprising determining parameters of the kinematic model based on measured positions of the radiation source and the imaging radiation detector for each of a plurality of configurations of the C-arm X-ray imaging apparatus;
• storing the sensor registration information and the joint calibration information;
• and subsequently:
• performing tracking by, with the X-ray imaging apparatus in a desired pose that places the radiation source and radiation detector at a desired position and orientation, the desired pose comprising desired positions for:
• the mechanical joints, a desired angle of orbit of the radiation source and radiation detector on the gantry arm and a desired angle of tilt of the gantry arm, computing the positions and orientation of the radiation source and the imaging radiation detector based at least in part on the sensor output signals, the stored sensor registration information and the stored joint calibration information to determine pose coordinates specifying the desired pose;
• and
• acquiring images comprising image data using the radiation source and radiation detector and associating with each of the images the corresponding pose coordinates specifying the pose of the X-ray imaging apparatus when the respective image was acquired.