1. Fluoroscopy
Historical Overview

2. Objectives of Lesson
Demonstrate knowledge of the development of the fluoroscopy equipment
Describe the anatomy and function of the eye with the types of vision.
Determine the relationship between the development of fluoroscopy equipment and the functionality of vision.

3. Timeline: Early development
Roentgen 1895: discovery of x-ray, he placed his hand between the tube and a screen and saw his fingers move.
1896: several other contributors, Salvioni of Italy, McGie of Princeton, and Thomas Edison.
Roentgen, in his creation of man-made x-rays, used a x-ray tube, and a fluorescent screen of calcium tungstate. He put his hand between the source and the screen and moved his fingers. This was the first dynamic image. He later worked with glass plates to create static images of anatomy, which includes an image of his wife’s hand. Salvoni called his invention the Cryptoscope, McGie’s was named a Sciascope. It was Thomas Edison who was already well-known, who received the most publicity, he named the dynamic imaging “fluoroscopy”.

4. Thomas Edison Using Fluoroscopy to Image Clarence Daly’s hand.
Thomas Edison and his assistant, Clarence Dally worked closely together, and were great friends. Clarence Dally began to experience physical symptoms of radiation over exposure, and eventually died. With the lost of his friend and colleague, Edison stopped working with radiation and fluoroscopy, He is reported to have said, I stopped working with x-rays, I am afraid of them.
Dally’s story is that in 1900, four years after he started the work with Edison, he began to show lesions and degenerative skin conditions on his hands and face. His hair began to fall out, then his eyebrows and eyelashes, too. Soon his face was heavily wrinkled, and his left hand was especially swollen and painful. He was a faithful researcher, committed to science, Dally found what he thought was the solution to prevent further damage to his left hand: He began using his right hand instead. The result might have been predictable. At night, he slept with both hands in water to alleviate the burning. Like many researchers at the time, Dally assumed he’d heal with rest and time away from the tubes. Retrieved from
Read more:
Credit: Science Source / Photo Researchers

5. Timeline Progression
1937- Irving Langmuir patented the image Intensifier
1948- J.W. Coltman improved upon the design so that the image brightness increased 1000 times.
1953- Westinghouse company manufactured the first commercial use Image Intensifier
The dangers of radiation were becoming well known, as you look at the arrangement again of the image of Thomas Edison, you can see that he is looking directly into the x-ray source. Granted, Dally had his hand even closer to the source.
The early images were very dim with unclear edges. Something had to be done to make the image brighter. This led to the development of the image intensifier to increase the brightness levels. This progression took almost 50 years!

6. 1940’s Fluoroscopy
A technician, as they were called in early years, using fluoro to image a female patient.
The technician is looking at a screen with the x-ray tube behind the woman. The technician is in the direct line of the source Do you notice that he has rubberized lead gloves on?
National Cancer Institute; public domain

7. 1950’s Fluoroscopy This was a shoe-fitting device
1950’s Fluoroscopy This was a shoe-fitting device. Viewed from above by the salesman and the parents, while the person trying on the shoes stood on the x-ray source.
This is the way that shoes were fitted before the dangers of radiation were widely known.
Image by Maury Markowitz at English Wikipedia, CC BY-SA 3.0,

8. Medical 1950’s fluoroscope The doctor looked into the screen directly in a darkened room. Photo taken 1952.
This image shows medical use of fluroscopy. The screen is above the patient and the x-ray source is below as we find in modern day units. Notice that there is not an image intensifier of viewing monitor.
Encyclopedia Britannica Films - Prelinger Archives. 

9. Improvements to early fluoroscopy
Improvements were slow, because the need to document findings found in fluoroscopy became more important, and radiation doses were high.
Static images had better spatial and contrast resolution.
Mirrors added so the person performing the procedure did not have to have eyes and face in the direct primary Beam.
Image Intensifiers were developed to increase brightness

10. Photopic and scotopic vision
Photopic vision is “daylight vision”
The current way that fluoroscopy is seen
Scotopic vision Is “ nighttime vision”
The darkened room or special goggles helped this vision
Fluoroscopists had to “dark adapt” before the image intensifier was developed. This meant sitting in a dark room for about 15 minutes or wearing specialized red lens googles when viewing the fluoroscopic screen. Dark adapt means activating the rods in the periphery of the retina.

11. The Eye: Cross sectional view
The cones are located within the Fovea centralis, the rods are found in the periphery of the retina layer.
The rods and cones are photoreceptors
Let’s look at the anatomy of the eye. This is basic anatomy, that we will look at to understand how the eye functions. This is foundational to the development of fluoroscopic equipment. Before the development of image intensifiers in fluoroscopy, the radiologist had to “dark adapt” their vision to see the images. The images in early equipment produced images that were very dim.
The eye is quite remarkable because it can adapt to many levels of light. The illumination that the eye can see is measured in lumens or candelas per meters squared. Cd/m2 or lumen/m2 also called “lux”. This is not important to memorize, just remember that it is the unit of measurement of any luminescence. This will pertain to monitor viewing.

12. Anatomy of the eye and function
From the most external to the internal
Cornea-Light passes through the transparent protective coating of the eye
Lens- shaped disc that focuses the incoming light onto the retina
Iris- this anatomy is between the cornea and the lens and acts like a diaphragm as it adjusts to control the amount of light coming into the retina.
bright light, the iris contracts, to limit the incoming light
low light, the iris dilates to allow more light to enter
The rods and cones are “embedded” in the retina.
There are 100,000 rods and cones per (mm)2 area
The rods are only in the periphery of the retina, and are sensitive to low light. They cannot respond to intense light, about 2 lux.
The cones are in a “pocket” called the fovea centralis, are less sensitive to light, and can respond to intense light, about 100 lux.
Diagnostic x-ray images are displayed at lux.
There are a hundred million rods and 6 million cones in the eye.
retrieved from

13. Rods and cones Cones are daylight vision (photopic)
this is where color is formed (red, blue, green)
Cones perceive small objects
This is where visual acuity is formed, the ability to see detail.
Cones can see variations in densities
This is contrast perception.
Rods are nighttime vision (scotopic)
dim objects are viewed peripherally, not when you look at it directly.
Light moves through the lens to the back of the eye, which is the retina
The light hits the discs of the rods and cones, the small amount of light photons activate the cells. Rods can be activated in low light, while cones need many more light photons to hit them to be activated.
3. The activated photoreceptor cells send the signal to neural cells.
4. the signal moves through the neural cells to the optic nerve.
5. the optic nerve sends the information to the brain, where the signal is processed, so the complete image can be seen as whole.
Cooper, K., Kazilek, C., (2010). Seeing Color. ASU - Ask A Biologist. Retrieved from
Beginning Psychology (v. 1.0) via Creative Commons (by-nc-sa 3.0). Labels modified for this page.

14. Vision and Fluroscopy
The dark adapt method was needed to activate rods when the dimly lit luminescence from the glass fluorescent plate would glow with the image. Risk of missing detail was higher with “rod” vision
Think about how much better you can see when your eyes are adjusted to the dark.
The goal for better image diagnosis is to have the cones activated image brightness needed to increase.

15. Review: What is the unit of measurement to measure luminescence?
Cd/m2 or lumen/m2 which is also known as lux
What is the function of the iris?
It acts as a diaphragm by constricting or dilating to allow light to reach the retina
Where are cones located
In the fovia centralis
What type of vision are they responsible and what are their unique functions
Daytime vision, photopic, color vision, visual acuity, contrast perception
What is nighttime vision called?
Scotopic
What’s the point?
The development of fluoroscopy equipment began with crude images that required high amounts of radiation to produce a dim and vague image that was difficult to view unless much preparation was done. “dark adapt”. Images were needed to be made brighter, and more protection for the person looking at the dynamic image directly, so they could be out of the direct source of radiation.