Latest high performance X-ray tubes for medical imaging

摘要

Why still vacuum technology to generate Bremsstrahlung, nearly 120 years after Conrad Roentgen's discovery? How do X-ray source and detection contribute to modern medical imaging? How do latest medical X-ray tubes work and look like? What's next? Will we see replacements of bremsstrahlung from practical sources for medical imaging in the clinical environment? After touching historic achievements to demonstrate the high level which the technology has today, we will shortly dive into physics of X-ray generation, study key characteristics, material boundary conditions, manufacturing technology. A particular focus area will be the generation of free electrons under the adverse conditions inside an X-ray tube, grid switching and focusing of the beam. The high level of residual gas as well as ion and discharge processes severely limit the range of suitable technologies. Other topics will be overall design concepts of glass and metal frame, single ended and dual polar tubes with reflection targets. We will touch the principle of rotating anode tubes, their bearings, anode discs, motors, cooling, heat balance, electron emitters and beam focusing, focal spot characteristics, off-focal radiation, and discuss the improvements of image quality by focal spot deflection.