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.

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We demonstrated that a dedicated design of a Talbot-Lau interferometer can be applied to medical imaging by constructing a preclinical Talbot-Lau prototype. We experienced that the system is feasible for imaging human-sized objects and the phase-stepping approach is suitable for clinical practice. Hence, we conclude that Talbot-Lau x-ray imaging has potential for clinical use and enhances the diagnostic power of medical x-ray imaging.

Parametric X radiation ͑PXR͒ produced by electrons with an energy of E 0 ϭ4 MeV interacting with the atoms in the ͑220͒ plane of a 20-m silicon and a 55-m diamond crystal and observed at an angle of 44°by a Si͑Li͒ detector has been investigated with respect to the interference with coherent bremsstrahlung ͑CB͒ that originates in the same interaction process between the incoming relativistic electron and the crystal. Since the energy of PXR and CB is identical, contributions of both types of radiation are indistinguishable. The newly derived analytical expressions describe the radiation which consists of a coherent superposition of PXR and CB. For the comparison of the experimental results with the theoretical predictions a Monte Carlo simulation taking into account all effects accompanying the radiation process has been performed. The comparison shows very good agreement between experiment and theory.

Parametric x rays (PXR) produced by bombarding silicon and diamond crystals with electrons of 30 to 87 MeV were detected at 180 degrees relative to the direction of the electron beam. It was found that the dependence of the intensity on the orientation of the crystal agrees with the predictions of the kinematical theory of PXR. The absolute intensity is twice as large as predicted. These findings can be explained considering dynamical effects that govern the x-ray crystal interaction. Additionally, x rays caused by self-diffracted transition radiation have been observed.