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

Abstract

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.

Computed tomography—old ideas and new technology

“…Siemens built a modern version of a so-called 'rotating-vacuum-vessel x-ray tube,' where the anode is in direct contact with cooling oil, resulting in a far greater heat capacity, despite a smaller anode [23]. The concept of this innovative tube goes back to a General Electric patent by Coolidge [24] in 1917, thus Fig.…”

Dose-efficient ultrahigh-resolution scan mode using a photon counting detector computed tomography system

“…Therefore, all photons with energy 25 keV or higher were used in the image reconstruction. The same x-ray tubes were used on the EID and PCD subsystems, each equipped with a UHR focal spot of nominal size 0.7 mm (Straton, Siemens Healthcare 35 ). Two scan protocols were available for the PCD UHR mode: (1) a head protocol using a carbon bowtie filter and (2) an abdominal protocol using both the carbon bowtie filter and an aluminum bowtie filter, 34 both with a 1 s rotation time.…”

Low-Jitter GaN E-HEMT Gate Driver With High Common-Mode Voltage Transient Immunity

“…In the following, the SNR of a sine-modulated half-bridge output is measured, which coincides with these static jitter measurements according to (3).…”

“…Correspondingly, Tab. IV summarizes the measured RMS jitter and SNR values as averaged values (arithmetic mean) from different operating conditions in order to compare them to the theoretically best achievable SNR according to (3), with f BW = 9700 Hz and m = 0.84, as this corresponds to the configuration of the SNR measurement. The measured jitter values follow the theoretical prediction accurately for the conventional gate driver with the jittery switch-node signal, despite its triangular-shaped distribution (cf.…”

“…MPORTANT industry applications, ranging from mechatronic wafer handling systems in integrated circuit manufacturing to X-ray computer tomography, require low-noise and low-distortion currents and/or voltages at power levels up to several kilowatts in order to, e.g., provide nanometerrange mechanical positioning or precise electron beam trajectories [1]- [3]. For positioning systems, the power amplifier output signal, which is usually a force or torque producing current, must be of low noise and low distortion in a limited frequency range from DC to ≈10 kHz, as undesired forces or torques at higher frequencies are sufficiently attenuated by the mechanical systems and do not lead to disturbing movements.…”