NASA's Low‑Intensity X‑Ray Patent: A Landmark in Technology Transfer
A detailed overview of U.S. Patent 4,142,101, NASA's 1979 invention describing a low‑intensity X‑ray and gamma‑ray imaging device that became the basis for the Lixiscope and later portable fluoroscopy systems.
NASA Technology Transfer
Part 5 of 5
U.S. Patent 4,142,101: Low‑Intensity X‑Ray and Gamma‑Ray Imaging Device
U.S. Patent 4,142,101, titled “Low intensity X‑ray and gamma‑ray imaging device,” was issued to Lo I. Yin on February 27, 1979, and assigned to NASA. The invention describes the compact, portable imaging technology that later became known as the Lixiscope (Low Intensity X‑Ray Imaging Scope). This device formed the technological foundation for lightweight, handheld fluoroscopic imagers used in medical, industrial, and security applications.
For the official NASA technology brief, go to https://ntrs.nasa.gov/citations/19780000061.
Technical Basis of the Invention
The patented device generates low‑intensity X‑rays or gamma rays using a radioactive source. These rays pass through an object and strike a scintillator screen, which converts the radiation into visible light. A microchannel plate (MCP)—a highly sensitive electron‑multiplying detector originally developed for space science—amplifies the visible image. The amplified output is then viewed directly, enabling real‑time imaging without the need for high‑power X‑ray generators or heavy shielding.
The system was designed to be portable, battery‑powered, and suitable for field use, weighing approximately 5–8 pounds. This made it valuable for emergency medical evaluation, nondestructive testing, and industrial inspection where conventional fluoroscopy was impractical.
A reexamination certificate for the patent was issued on February 19, 1991, confirming the validity of its core claims.
Applications and Industry Use
The Lixiscope became widely used in settings requiring low‑dose, on‑site imaging, including:
- Portable medical fluoroscopy
- Emergency field diagnostics
- Security screening
- Quality control and nondestructive inspection
- Industrial materials evaluation
Its minimal radiation output allowed imaging in environments where traditional X‑ray systems would require shielding, controlled rooms, or specialized safety equipment.
Later technical developments explored replacing the radioactive source with a conventional X‑ray tube, creating an electrically powered version of the device. NASA technical reports such as Characterization of Low Intensity X‑Ray Imaging Devices document these efforts, showing how the Lixiscope could be driven by standard X‑ray generators while maintaining low‑dose performance.
Scope of the Patent
According to Lixi, Inc., the company that commercialized the Lixiscope, U.S. Patent 4,142,101 covers the essential configuration and operation of the low‑intensity imaging device. This includes both:
- Isotope‑based versions, which use a small radioactive source
- X‑ray tube versions, which use electrically powered X‑ray generators
The patent protects the imaging chain that defines the Lixiscope: low‑intensity radiation generation, scintillator conversion, MCP amplification, and direct viewing. These elements enabled real‑time imaging with far lower radiation than conventional fluoroscopes.
