Spire Corporation

Massachusetts Institute of Technology

Air Products and Chemicals, Inc.

Ward D Halverson

Leslie Bromberg

Daniel R Cohn

Paul P Woskov

Benjamin Lax

Diwakar Garg

Paul N Dyer

Piran Sioshansi

Anton C Greenwald

George Vakerlis

Robert D Evans

The present invention provides a catheter having an x-ray generator unit at its tip which generates x-ray radiation having a wavelength in a range effective for treating biological tissue. In one embodiment, the x-ray generator unit includes a miniature x-ray generator and a miniature transformer that form, in combination, a monolithic device. The transformer includes a primary winding that receives an input voltage in a range of 100 V to 4 kV from a power source, via a flexible cable that runs from the proximal end of the catheter body to its distal end. The transformer further includes a secondary winding that up-converts the input voltage to generate an output voltage in a range of 10 kV to 40 kV to be applied to a cathode of the x-ray generator. The cathode emits electrons in response to the applied voltage, and an extraction electrode guides the emitted electrons to an anode, which is preferably formed of a high-Z refractory metal. The impact of the electrons with the anode effects generation of x-ray radiation, a portion of which is transmitted via an x-ray transmissive window to the outside environment. One significant advantage of the device of the invention is that by employing a lower voltage in the body of the catheter and confining a higher voltage to a short, rigid section at the distal end of the catheter, the device provides enhanced mechanical flexibility and lowers the likelihood of electrical breakdown.

Catheter tip x-ray source

The structures for confining or guiding high frequency electromagnetic radiation have surfaces facing the radiation constructed of high temperature superconducting materials, that is, materials having critical temperatures greater than approximately 35.degree. K. The use of high temperature superconductors removes the constraint of the relatively low energy gaps of conventional, low temperature superconductors which precluded their use at higher frequencies. The high temperature superconductors also provide larger thermal margins and more effective cooling. Devices which will benefit from the structures of the invention include microwave cavities, millimeter-wave/far infrared cavities, gyrotron cavities, mode converters, accelerators and free electron lasers, and waveguides.

Microwave/far infrared cavities and waveguides using high temperature

An improved capacitively coupled radio frequency-plasma enhanced chemical vapor deposition (PECVD) apparatus and process are disclosed for depositing a uniform coating of material on substrates. The apparatus includes a secondary electrode defining a reaction zone within an outer chamber and an RF electrode in concert with the secondary electrode for generating a plasma within the reaction zone. The electrode comprising a base and a finger extending through the reaction zone for distributing a plasma field uniformly throughout the reaction zone. The process comprises heating a substrate to a deposition temperature in the range of about 300.degree. to 650.degree. C. Reactant gases are introduced into the PECVD reactor and a coating of about 0.2 to about 20 .mu.m is deposited onto the heated substrate. This low temperature process is particularly adapted to coating three-dimensional objects of metals, metal alloys and mixtures of metals.

Radio frequency plasma enhanced chemical vapor deposition process and

The structures for confining or guiding high frequency electromagnetic radiation have surfaces facing the radiation constructed of high temperature superconducting materials, that is, materials having critical temperatures greater than approximately 35.degree.K. The use of high temperature superconductors removes the constraint of the relatively low energy gaps of conventional, low temperature superconductors which precluded their use at high frequencies. The high temperature superconductors also provide larger thermal margins and more effective cooling. Devices which will benefit from the structures of the invention include microwave cavities, millimeter-wave/far infrared cavities, gyrotron cavities, mode converters, accelerators and free electron lasers, and waveguides.

A metal alloy with a treated surface and the process of effecting the treated surface are disclosed whereby its ion release under static, stress and crevice corrosion and corrosive wear conditions is reduced. The metal alloy preferably is an ASTM F-75 Co-Cr-Mo alloy. The preferred process includes providing a workpiece formed of such a metal alloy with a coating of biologically compatible elements, such as a noble metal and then exposing the thus coated surface thereof to bombardment by an ion beam, whereby a plurality of noble metal atoms, together with a plurality of ions from the beam, are driven into the surface of the workpiece a certain distance. Another preferred process includes the direct ion implantation of a workpiece with biocompatible elements, such as nitrogen, tantalum and inert gas ions. Preferably, such a workpiece finds application as an orthopaedic implant.

Corrosion inhibition of metal alloys

An improved process, optimizing quality and growth rate with independent control of residual stress, is disclosed for the growing of membranes for use as X-ray lithography mask blanks. The process comprises providing a mounting fixture and a low-cost substrate material thereon, cooling the substrate to about the boiling point of hydrogen by passing a liquid coolant in contact with the fixture, depositing by a low-temperature plasma-enhanced method a thin membrane onto the cooled substrate, removing the substrate and the thereon deposited membrane from the fixture, and allowing the substrate thermally to expand by gradually assuming ambient room temperature, whereby the membrane will acquire optimum tensile stress. Preferably, the low-cost substrate is low grade industrial silicon and the membrane is formed of boron nitride, silicon carbide, silicon nitride, amorphous silicon, diamondlike carbon, aluminum oxide, beryllium and silicon oxide.

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Cambridge, MA, United States of America

Ward D Halverson