Electro-optic imaging chain for a biplanar fluorscope for neurosurgery: magnetic field sensitivity and contrast measurements

Abstract

The effects of magnetic fields on the microchannel plate (MCP) image intensifiers to be used in a novel biplanar fluoroscope are studied along with the system's overall contrast as a function of beam energy. For a second-generation device with wrap-around power supply, B-3dB values for the gain roll-off were found to be approximately 0.08 T (axial field) and 0.06 T (transverse field). the maximum image shift resulting from a 0.0035-T transverse field is found to be 0.065 mm, limited by centroid location error resulting from low-dose x-ray noise. the results of x-ray contrast studies suggests that the presently estimated 0.1-rad dose delivered to the patient (2-h magnetic stereotaxis procedure; 12% ''fluoro-on'' duty cycle) might be reduced by increasing the x-ray energy.