TRACKING SYSTEM FOR IMAGING MACHINES AND RELATED APPARATUS

摘要

An imaging system such as a medical C-arm x-ray fluoroscopy machine includes a tracking system that tracks a position of an x-ray source and an x-ray detector using sensors which monitor positions of joints which allow relative motions of segments in a support for the x-ray source and detector. Sensor readings are used in a kinematic chain. One or more segments that behave in a non-rigid manner are replaced by a virtual rigid link in the kinematic chain that takes into account deformations of the segments (e.g. under the influence of gravity). Calibration methods permit calibration of the system using images of phantoms.

主权项

1. A medical imaging apparatus comprising:
a support operable to hold an imaging head at a desired position relative to a patient, the support comprising a base and three or more segments connected to one another by adjustable joints such that a first one of the segments is coupled to the base by a first one of the adjustable joints and the imaging head is supported on a last one of the segments and is movable in space by adjusting the adjustable joints; a plurality of sensors, the plurality of sensors operative to monitor configurations of each of the adjustable joints; a data processor connected to receive outputs from the plurality of sensors and to estimate a current position of the imaging head by: treating a first set of the segments comprising a first plurality of the segments and the adjustable joints between them as a first part of a kinematic chain, the first part of the kinematic chain extending from the base to an end of the first part of the kinematic chain, the first part of the kinematic chain excluding a second set of the segments comprising one or more second segments including the last segment and determining a position of the end of the first part of the kinematic chain relative to the base based on geometries of the first plurality of the segments and configurations of the adjustable joints included in the first part of the kinematic chain, the configurations of the adjustable joints included in the first part of the kinematic chain determined from the outputs of the sensors; determining from the output signals of the sensors a configuration of each of the one or more of the adjustable joints located between the end of the first part of the kinematic chain and the last segment and based on the determined configurations of the one or more of the adjustable joints located between the end of the first part of the kinematic chain and the last segment, looking up first calibration coordinates indicative of a vector displacement of the imaging head relative to a point having a predetermined location relative to the end of the first part of the kinematic chain; and based on the first calibration coordinates extending the kinematic chain from the end of the first part of the kinematic chain to the imaging head.