Infrared camera imaging algorithm to augment CT-assisted biopsy procedures

The problem with CT guided biopsies is the high dosage of radiation exposure to the patient, the time it takes to perform the procedure and the lack of spatial reference of the operator. We approach this problem by using a system comprising of two digital infrared sensitive cameras and a high intensity infrared illuminator which was used to capture the coordinates of an infrared reflective tape attached to a coaxial biopsy needle having been inserted into a test phantom. Data was sent in real-time to a computer where the infrared needle position coordinates were recorded. A CT scan of the test phantom was then taken and the DICOM CT image coordinates of the needle were also recorded. The approach is to use a linear least-squares model to map points from each camera to a single point on each DICOM CT image resulting from the CT scan. Results show a promising mapping accuracy with limited data. The contribution of this paper is to show that a passive infrared imaging system using at least two cameras may be suitable for the needle estimation task in two dimensions which would allow real-time needle placement in any plane.