In 1992 IEEE Nuclear Science Symposium and Medical Imaging Conference Record, volume 2, pages 1331-3, Orlando, Florida, 29-31 October 1992.
Microfocus x-ray sources with focal spot sizes in the 1-10 micron range are useful for very high resolution microradiography and microtomography of biologic specimens and industrial parts. Pinhole measurements are not applicable for measuring the size of such focal spots since the output flux is extremely low and the smallest aperture readily available is too large (about 2 microns). We have developed a method using high magnification, high resolution, digital radiographs of a precise edge to obtain quantitative estimates of focal spot dimensions. The x-ray intensity distribution is determined from the edge response. The method has been used to assess the relationship between focal spot size and tube potential (kVp) for an x-ray source in which the electron beam is focussed with an electromagnetic device.