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Dornier Compact S

The shock wave system utilizes electromagnetic technology to generate a shock wave. A convex lens focuses the shock wave into the therapeutic focal point. The electromagnetic therapy head (EMSE) is isocentrically integrated within the x-ray C-arm system which moves as a single unit in three axis (x, y, z) around the patient. When the localization system is in focus with the stone, the shock wave focus is simultaneously in focus. The therapy head is coupled to the patient's body via a water cushion. Shock waves are released from 70 to 120 shocks per minute, or may be released via ECG triggering as needed. Shock waves are produced over a broad energy range, either as a "low energy" or a "high energy" lithotripter.

The electromagnetic Shock Wave Emitter (EMSE) works on a similar principal to a loud speaker.

On a more detailed level, the process begins when the shock wave generator, a high-voltage capacitive charging device located in the equipment cabinet, charges a capacitor located within the control cabinet to a voltage of several kilovolts. After charging, the electric energy is available for a high-energy discharge of short duration. This discharge, initiated through the control panel, occurs in a few microseconds and results in ignition of a high current / high-voltage triggered spark gap.

The discharge circuit consists of the storage capacitor, triggered spark gap, and slab coil. The slab coil (primary side) is separated by an insulating layer opposite a highly conductive metallic foil quasi as a short-circuiting coil (secondary side). The low total inductivity of this configuration causes a steeply rising current pulse with an intensity maximum of several kiloamperes. The current pulse in the slab coil induces a back potential in the metallic layer (membrane) acting as a secondary coil, resulting in the magnetic repulsion of the two components.

The boundary of the coil toward the rear provided by an acoustically "hard" ceramic base causes a deflection of the metallic layer (membrane) toward the nearby wave-propagating medium (water). This causes a shock wave within the water, the intensity of which is proportional to that of the current pulse and which is propagated with the speed of sound in the axial direction away from its source. At a sufficiently large distance, at the end of its path in the water, a plane shock wave results. This is then focused by means of a convex acoustical lens with a diameter of 140 mm, in order to produce sufficiently great and steep pressure amplitudes over a limited volume for the effective destruction of renal stones.

The shock wave focus size (focus volume) is approximately 80 x 7 mm at a distance 130 mm from the EMSE acoustic lens at power level 7. The maximum shock wave pressure is 400 Bar.

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