Abstract: An invasive lithotripter includes a pair of electrodes having rectangular cross sections, and having flat faces of rectangular configuration confronting one another. An insulating member is interposed between the electrodes and spaces them apart a predetermined distance. The insulating member at its forward edge is relieved to provide portions of the electrode flat faces exposed and confronting one another to permit an electrical spark to jump between the exposed portions of the electrode faces. The relieved portion comprises a reflector having a focus point. The portions of the electrodes facing one another across the relieved area are provided with protuberances aligned with the focus point. A spark across the exposed portions of the faces of the electrodes in an aqueous medium generates a shockwave that is focused by the reflector. A shield surrounds and extends beyond the electrode and the insulating member to inhibit radial propagation of shockwave energy while enhancing axial propagation thereof.

Abstract: An improved housing construction for electrical apparatus is disclosed, the housing having particular utility as a housing suitable for an ionization detector array of a tomographic X-ray scanner. The housing comprises at least two mating sections which, upon assembly and juxtaposition one to another, form a closed interior chamber adapted to receive the detector array, or other electrical apparatus. A gasket means preferably comprising a so called "flexible" printed circuit constructed of a suitable polymer plastic is provided between the assembled mating sections of the housing to effect a sealing of the interior chamber. Electrical conductors, such as a metallic printed circuit foil, are disposed within the polymer material and extend between the interior chamber and the exterior of the housing. The conductors define means by which electrical connections can be made to electrical apparatus within the chamber, such as the detector array, and external circuitry.

Abstract: A collimator is disclosed for minimizing radiation exposure and improving resolution in radiation imaging devices. The collimator provides a penetrating beam of radiation from a source thereof, which beam is substantially non-diverging in at least one direction. In the preferred embodiment, the collimator comprises an elongated sandwich assembly of a plurality of layers of material exhibiting relatively high radiation attenuation characteristics, which attenuating layers are spaced apart and separated from one another by interleaved layers of material exhibiting relatively low radiation attenuation characteristics. The sandwich assembly is adapted for lengthwise disposition and orientation between a radiation source and a target or receiver such that the attenuating layers are parallel to the desired direction of the beam with the interleaved spacing layers providing direct paths for the radiation.