Peter Schardt

New x-ray tube performance in computed tomography by introducing the rotating envelope tube technology.

The future demands of computed tomography imaging regarding the x-ray source can be summarized with higher scan power, shorter rotation times, shorter cool down times and smaller focal spots. We report on a new tube technology satisfying all these demands by making use of a novel cooling principle on one hand and of a novel beam control system on the other hand. Nowadays tubes use a rotating anode disk mainly cooled via radiation. The Straton x-ray tube is the first tube available for clinical routine utilizing convective cooling exclusively. It is demonstrated that this cooling principle makes large heat storage capacities of the anode disk obsolete. The unprecedented cooling rate of 4.8 MHU/min eliminates the need for waiting times due to anode cooling in clinical workflow. Moreover, an electronic beam deflection system for focal spot position and size control opens the door to advanced applications. The physical backgrounds are discussed and the technical realization is presented. From this discussion the superior suitability of this tube to withstand g-forces well above 20 g created by fast rotating gantries will become evident. Experience from a large clinical trial is reported and possible ways for future developments are discussed.

Physics of X-ray generation in high-voltage devices

Summary form only given as follows. X-rays are widely used in medical diagnostics as well as material sciences and engineering. Dedicated devices have been developed for the generation of this useful radiation. Nevertheless lots of other devices emit x-rays as an unwanted radiation, which has to be shielded to avoid harmful danger to users or others. Especially every high voltage device is a candidate for the emission of x-rays. An overview of the basic physics of x-ray generation is given in the talk. Subsequently the parameter ranges with respect to energy and intensity of the emitted x-rays are discussed. The use and the shielding of the x-rays is then illustrated with tube designs of various kinds of x-ray sources ending up in a discussion of the necessity of x-ray shielding in vacuum circuit breaker design.