You can freely build on How Early CT Scans Created Detailed Body Images

What this patent covers

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 is now free to use

All 1 claims of US 3778614 are in the public domain. Specifically:

The 1 dependent claim add narrowing limitations and are also free.

What is NOT covered

Patent expiry frees this specific invention. Separately-patented improvements made after expiry may still be protected.

• 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.

Who is building on this today

The foundational principles of this patent are embedded in virtually all modern CT scanner manufacturers, including GE Healthcare, Siemens Healthineers, Philips, and Canon Medical Systems. Research continues to refine image reconstruction algorithms and detector technologies.

Products built on expired version of this technology

How to cite this patent in your documentation

EMI Ltd. US Patent 3778614. Method and apparatus for measuring x- or {65 -radiation absorption or transmission at plural angles and analyzing the data. Granted 1973, expired 1991. Now in the public domain.

Note: This is a convenience citation. Consult a patent attorney for formal freedom-to-operate analysis.

PatentBrief is an educational resource and does not provide legal advice. Patent expiration information is derived from USPTO records and may not reflect continuation patents, divisional filings, or separately-patented improvements. For commercial use or production decisions, obtain a formal freedom-to-operate (FTO) opinion from a registered patent attorney.