Earliest possible detection of breast carcinoma requires exceptional spatial resolution and contrast, which are of prime importance for the visualization of fine detail in mammographic images, particularly if captured digitally. Image quality depends greatly on the following improvements: smaller, uniform and variable focal spots, shorter exposure time, minimized off-focus x-rays, and optimized x-ray spectrum. Current x-ray tube technology is close to its limits. A more radical change in tube design is proposed here to improve image quality by transferring and adapting advanced technologies found in other fields to x-ray tube design: (a) metal-ceramic oil free construction, (b) advanced rotor dynamics allowing ultra-fast rotation, (c) advanced cathode technology based on novel electors emitters and computer synthesized gun, (d) multi-element target together with electron beam deflection capability. A three step approach is proposed: (1) Develop compact metal-ceramic, oil-free x-ray tube with new type cathode. Purpose: field compatible tube with superior focal spot, reduced exposure time, negligible off- focus radiation. (2) Develop ultra-fast (60,000 rpm) rotor. Purpose: greatly increased power levels in conjunction with high density electron beams, to minimize focal spot size and exposure time further. (3) Design for minimized off-focus radiation. Purpose: improved image contrast. (3) Design for minimized off-focus radiation. Purpose: improved image contrast.
Greatly improved performance of mammography X-ray tubes will make them the preferred choice for new machines (U.S. market: 2,000/yr) as well as for replacements (U.S. installed base: 13,000, 1 tube per 2 years: total 6,500 tubes/yr). Because of air cooling: replacement in field possible.
