Ultrasound Transducer Tracking System For Correlation Of Masses In Combined X-Ray And Manual Breast Ultrasound Imaging

Breast ultrasound has been used in the USA primarily as an adjunct breast cancer diagnosis to projection x-ray mammography or DBT. Ultrasound is employed in screening in most of the world and its use for such dense breast is increasing in the USA. In either application, finding corresponding masses in images from both x-ray and ultrasound is time-consuming and prone to correlation errors, leading to delays in cancer diagnosis. Previously, we have shown that, when automated breast ultrasound is performed through a special mammographic paddle in the same or slightly reduced compression as the x-ray exam, such correlation errors were reduced([1-2]). Even for hand-controlled scanning, it should be useful to track the physical position and orientation of the ultrasound transducer in the coordinates of the x-ray to help in reducing both exam time and correlation errors in mass identification. A tracking system for hand scanning through a mesh mammographic paddle is achieved via the coordination of a full-HD camera and a 6-axis sensor, locates the path of the real time ultrasound image plane through the x-ray image or image stack. The tracking system requires minimal setup, with the camera mounted to a fixed location relative to the paddle and the 6-axis sensor attached to the transducer body. The tracking system can achieve an overall frame rate of 5 Hz and mean position error within 6.62mm. In a parallel display, a mass identified in the x-ray image volume will be used to generate trajectories for an ultrasound transducer to reach the same mass. Feasible, improved position tracking should allow creation of spliced 3D volumes and precise, multimodality image fusion.