First U.S. patent for whole-body X-ray scanner - November 25, 1975

On this day in 1975, Robert S. Ledley was awarded the first U.S. patent for a whole-body X-ray scanner. 

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Episode Transcript

Speaker 1 (00:00):
This Day in History Class is a production of I
Heart Radio. Hey everyone, I'm Eves and welcome back to
This Day in History Class, a podcast where we unwrap
a piece of history candy every day. Today is November.

(00:25):
The day was November nine. The first US patent for
a whole body X ray scanner was issued to Robert S. Ledley.
Scientists have been working on developing X ray computed tomography
technology for years. South Africa born physicist and mathematician Alan
Cormick's main work was in particle physics, but he theorized

(00:47):
that X rays of the brain and body could be
taken from different angles and the computer could be programmed
to arrange the images into three D representations. British electrical
engineer got Free Houmsfield developed a ct or computerized tomography
machine that could carry out brain scans, and he began
testing it in nineteen seventy one. He announced his invention

(01:10):
publicly in nineteen seventy two. The first CT scanner that
Houndsfield developed in his lab at E. M I Central
Research Laboratories in England took several hours to get the
raw data for a single scan, in days to reconstruct
an image from the raw data. The first production model
e m I scanner took four minutes to make a
scan and its mini computer took about seven minutes to

(01:32):
compute each picture. In the US, Robert Letley was working
in the School of Medicine at Georgetown University Medical Center
as a professor in the Department of Physiology and Biophysics.
Letley previously studied dentistry and theoretical physics and worked as
a physicist, research analysts, and professor of electrical engineering. In

(01:54):
nineteen seventy three, while at Georgetown, he developed the first
whole body CT machine. Let Lee's invention was known as
the a c t A or Automatic Computerized Transverse Axial
Diagnostic X ray scanner. It provided images of the body
and brain that could not be seen with normal X rays.
This was because the device used computers to generate three

(02:17):
dimensional images from flat X ray pictures of cross sections
of the body. The technology allowed doctors to precisely locate
at normal tissue, which could provide for early diagnosis of
illness and disease. Let Lee's patent for the machine number
of three million, nine two thousand, five hundred and fifty two,
issued on November nineteen fifteen recognizes precedents for quote the

(02:41):
concept of utilizing X ray scanning with thin beams for
analysis by computers for storing and reconstructing the results in
tangible form, as well as quote the concept of rotational
scanning by X rays for the reconstruction of planer anatomical sections.
The patent describes a sheen for examining the interior of

(03:02):
a patient that consists of a movable support, a frame
with an opening that the patient can enter into a
shutter assembly, an X ray beam source and detector unit
mounted on the opening of the frame, and mechanisms for
rotating and tilting the framework. Let Lee scanner set the
foundation for modern CT scanners, as it made use of

(03:22):
the first high resolution digital TV display for medical imaging
and a tilting gantry or circular frame. The technology also
improved the diagnosis of cancers, heart disease, and bone disease,
and was used in radiation therapy planning. I'm Eave Scheffco
and hopefully you know a little more about history today

(03:43):
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(04:13):
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