FLUOROSCOPY

What is fluoroscopy?
X-RAYS IN MOTION "Viewing dynamic studies of the human body"
Fluoroscopy is a technique for obtaining "live" X-ray images of a living patient - it is like an X-ray TV camera. The Radiologist uses a switch to control an X-Ray beam that is transmitted through the patient. The X-rays then strike a fluorescent plate that is coupled to an "image intensifier" that is (in turn) coupled to a television camera. The Radiologist can then watch the images "live" on a TV monitor.


HISTORY OF FLOUROSCOPY

Thomas Edison, 1896
Screen (zinc-cadmium sulfide) placed over patient’s body in x-ray beam
Radiologist looked directly at screen
Red goggles-30 minutes before exam
1950 image intensifiers developed
www.cerebromente.org.br/.../xray-fluoroscope.JPG

PRESENTLY
Fluoro viewed at same level of brightness as radiographs (100-100 lux)
X-ray tube under table/over table or in c-arm
Image intensifier above patient in carriage
Carriage also has the power drive control, spot film selection and tube shutters

Courtesy of Scott Sorenson, 2000









Purpose of Fluoroscopy
The principal advantage of image intensified fluoro is an increased brightness
Sometimes requires that the room be dark so that the image can be visualized better

Human vision structures designed for vision


Rods: Sensitive to low light levels. Used in night vision (scotopic vision)
Cones: Sensitive to bright light levels. Daylight vision (phototopic vision)

Fluoroscopic technique
Maximum detail is desired, Image brightness must be high, Controlled by automatic brightness control (ABC) Generally high kVp and low mA are preferred kVp relates to the body part being examined mA is around 5 Much lower than hundreds of mA usually used for static imaging

Components of the image intensifier tube Input phosphor

Glass envelope
Photocathode
Electrostatic lenses
Anode
Output phosphor

Glass envelope
Surrounds all of the components and provides mechanical support of internal components has a vacuum tube.

Input phosphor
Receives incident x-rays from the x-ray tube and converts them into light Composed of cesium iodide

Photocathode
Attached to the input phosphor by an adhesive layer, Converts light from input phosphor to electrons by photoemission Negative portion of the tube

Anode
Positive portion of the tube. A circular plate with a hole in it in which electrons are focused to which goes to the output phosphor

Electrostatic focusing lenses
Focuses electron path form photocathode to anode by means of repulsion

Output phosphor
Converts electrons from anode to light


Multifield Image Intensification
Gives the fluoroscopist the ability to magnify the video image of the body part examined. Sometimes referred to as a “Mag” view Electrostatic focusing lenses focus electrons in a smaller area on the output phosphor which makes the resulting image larger than the original.


(Cross section of the II-TV system illustrates the various components that are used to create the highly amplified output light image. A four stage process (x-rays to light; light to electrons; electrons to light; light to electronic signal) is shown)

What are the types of fluoroscopic tests?
Fluoroscopy, as an imaging tool, enables physicians to look at many body systems. Fluoroscopy may be performed to evaluate specific areas of the body, including the bones, muscles, and joints, as well as solid organs such as the heart, lung, or kidneys.


Fluoroscopic exams include the following types of tests: barium swallow, upper GI series, small bowel series, barium enema, hystersalpingogram, intravenous pyelogram, voiding cystourethregram, myleogram, arthrogram, biopsy, lumbar punctures and facet injections

Fluoroscopy Equipment
Fluoroscopic table




C-arm