# How Early CT Scans Created Detailed Body Images > This 1973 patent describes a method for using X-rays from many angles to build a detailed 2D image of the inside of a body, like a slice of a CT scan. - **Patent:** US 3778614 - **Original title:** Method and apparatus for measuring x- or {65 -radiation absorption or transmission at plural angles and analyzing the data - **Owner:** EMI Ltd - **Granted:** 1973 - **Status:** Public domain (expired) - **Times cited:** 163 - **Field:** biotech, medical_devices, semiconductors ## What it does This patent details a method for creating a 2D image of a body slice using penetrating radiation, like X-rays. Radiation is sent through the body from many different angles, passing through many paths. Each path's 'transmission' (how much radiation gets through) is measured. The patent claims a way to use these measurements, especially by 'successive approximations' where calculations are repeatedly refined, to figure out the absorption or transmission of tiny, individual elements within the body's 2D matrix. These refined values are then used to create a visual representation, like on a screen or photo, showing the internal structure. For example, imagine shining X-rays through a slice of your arm from the front, then the side, then diagonally, and using those readings to map out the density of bone versus muscle in each tiny spot. ## What it does NOT cover - Methods that only use radiation from a single angle. - Imaging techniques that don't involve measuring radiation transmission or absorption. - Creating 3D images instead of 2D slices. - Methods that don't use a 'successive approximation' process to calculate internal element values. - Using radiation sources other than X-rays or gamma rays. ## The clever bit The core innovation was developing a mathematical method, specifically 'successive approximations,' to reconstruct a detailed 2D image from numerous, incomplete X-ray measurements taken at different angles. This allowed for the differentiation of absorption coefficients of neighboring elements, which was crucial for creating diagnostic images. ## Real-world examples 1. Early CT scanners 2. The technology behind modern CT imaging ## Why it matters This patent is foundational to the development of computed tomography (CT) scanning. Sir Godfrey Hounsfield, one of the inventors, won the Nobel Prize in Physiology or Medicine in 1979 for his work on this technology. CT scans revolutionized medical diagnostics by providing detailed cross-sectional images of the body, enabling doctors to see internal structures with unprecedented clarity. ## Frequently asked questions ### What does How Early CT Scans Created Detailed Body Images cover? This 1973 patent describes a method for using X-rays from many angles to build a detailed 2D image of the inside of a body, like a slice of a CT scan. ### Who owns patent US 3778614? EMI Ltd owns this patent, granted in 1973. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 3778614 cited by? This patent has been cited by 163 later patents that build on its ideas. ### What problem does this patent solve? This patent is foundational to the development of computed tomography (CT) scanning. Sir Godfrey Hounsfield, one of the inventors, won the Nobel Prize in Physiology or Medicine in 1979 for his work on this technology. CT scans revolutionized medical diagnostics by providing detailed cross-sectional images of the body, enabling doctors to see internal structures with unprecedented clarity. ### What does this patent NOT cover? Methods that only use radiation from a single angle. **Full plain-English explainer:** https://patentbrief.org/patent/us/3778614/ct-scanner-hounsfield **Original patent:** https://patents.google.com/patent/US3778614 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [Using Nuclear Magnetic Resonance to Detect Cancer in Tissue](https://patentbrief.org/patent/us/3789832/mri-magnetic-resonance-imaging) — This 1974 patent describes a method and apparatus using nuclear magnetic resonance (NMR) to measure how quickly certain atomic nuclei in a tissue sample return to their normal energy state, helping to distinguish cancerous from healthy tissue. - [Catheter System for Opening and Closing Body Passages](https://patentbrief.org/patent/us/4195637/balloon-angioplasty-catheter-gruentzig) — This 1980 patent describes a medical catheter system with a guide catheter and a special dilatation catheter that can expand to open or close body passages, like blood vessels. - [How Laser Printers Use Rotating Mirrors to Write Information](https://patentbrief.org/patent/us/3867571/laser-printer-starkweather) — A 1972 Xerox patent describing how to use a spinning mirror to scan a laser beam across a page, adjusting the speed of the data to keep the image sharp. - [The First Digital Camera's Core Technology](https://patentbrief.org/patent/us/4131919/digital-camera-electronic-still) — Kodak's 1978 patent on the fundamental technology for capturing, processing, and storing digital images using a CCD sensor and magnetic tape. - [How Lasers Correct Vision by Reshaping the Eye's Front Surface](https://patentbrief.org/patent/us/4665913/laser-eye-surgery-lesperance) — This patent describes a method for precisely reshaping the front surface of the eye using an ultraviolet laser to correct vision problems like nearsightedness, farsightedness, and astigmatism.