1. Fluoroscopy uses x-rays to provide real-time images of internal body structures and motion. Early fluoroscopes consisted of an x-ray tube, table, and faint fluorescent screen viewed in a dark room. 2. The development of the image intensifier in the 1950s allowed for brighter fluoroscopic images. Image intensifiers use a photocathode, electrostatic lens, and output phosphor to amplify the x-ray image thousands of times. 3. Modern fluoroscopy uses cesium iodide and silver screens, along with high voltage electron acceleration, to produce bright, minimally distorted images that can be viewed on monitors or recorded with video cameras.

1. Fluroscopic Imaging
Image Intensifier Design
Vidicon & CCD Camera

2. Fluoroscopy
 A technique used to furnish images that
reflect near instantaneous changes occurring in the
patient.
Purpose
 organ motion
 ingested or injected contrast agents
 insert stents
 cathetarize small blood vessels

3. Fluoroscopic Imaging
 First generation fluoroscopes consisted of an x-ray
tube, an x-ray table and a fluoroscopic screen.
 The fluorescent material used in screen was copper
activated zinc cadmium sulfide that emitted light in
yellow-green spectrum.
 A sheet of lead glass covered the screen, so that
radiologist could stare directly into the screen with out
having the x-ray beam strike his eyes.
 Screen fluoroscence was very faint so, the examination
was carried out in a dark room by the radiologist who
had to adapt his eyes by wearing red goggles for 20-30
mins prior to the examination  technique is now
obsolete & gone.

4. FLUOROSCOPY

5.  Photograph
shows an
early (1933)
fluoroscopic
system in use
before the
development
of image
intensificatio
n. An actual
fluoroscopic
examination
with this
device would
have
occurred in a
darkened
room.

6. Fluoroscopic Equipment

7. Fluoroscpic Equipment
 Mobile
fluoroscopic
system for
routine
procedures
during
surgery

8. IMAGE INTENSIFIER DESIGN
 Image intensifier was discovered in 1950s-to produce
an image bright enough to allow cone vision without
giving the pt an excess radiation exposure.
 The components of an x-ray image intensifier
 The tube itself is an evacuated glass envelope, a
vacuum tube containing-
1.input phosphor and photocathode .
2.electrostatic focusing lens.
3.accelerating anode.
4.out put phosphor.

10. IMAGE INTENSIFIER DESIGN
1. After an x-ray beam passes the pt it enters the image
intensifier tube the input fluorescent screen
absorbs x-ray photons and converts their energy into
light photons.
2. The light photons strike the photo cathode, causing it
to emit photoelectrons  these electrons are
immediately drawn away from the photocathode by
the high potential difference betn it &the accelerating
anode.
3. As the electrons flow from the cathode towards the
anode, they are focused by an electrostatic lens which
guides them to the output fluorescent screen without
distorting their geometric configuration.

11. IMAGE INTENSIFIER DESIGN
4.The electrons strike the output screen, which emits the
light photons that carry the fluoroscopic images to
the eye of the observer.
5.In intensifier tube, the image is first carried by the x-ray
photons, then by the light photons, next by the
electrons &finally by the light photons.

12. Input Phosphor & Photocathode
 The input fluorescent screen in image
intensifiers is cesium iodide (CsI). (older
intensifier- silver activated zinc cadmium
sulfide).
 CsI is deposited on a thin aluminum substrate
by a process called “vapor deposition”.  an
interesting & useful characteristic of CsI is that
during the deposition process the crystals of
CsI grow in tiny needles perpendicular to the
substrate.  There by reducing scattering.

13. Photocathode
 The photo cathode is a photoemissive metal
(commonly a combination of antimony &
cesium compounds).
 When the light from the fluorescent screen
strikes the photo cathode, photo electrons are
emitted in numbers proportional to the
brightness of the screen.
 The photoelectrons thus produced has to be
moved to the other end of the image intensifier.
This can be done using an electrostatic focusing
lens and an accelerating anode.

14. Electrostatic Focusing Lens
 The lens is made up of a series positively charged
electrodes that are usually plated on to the inside
surface of the glass envelope.
 These electrodes focus the electron beam as it flows
from the photocathode toward the output phosphor.
 Electron focusing inverts & reverses the image which is
called “point inversion” because all the electrons pass
through a common focal point on their way to output
phosphor.
 The image on the output phosphor is reduced in size
,which is one of the principle reasons why it is brighter.

15. ACCELERATING ANODE :
•The anode is located in the neck of the image tube.
•Its function is to accelerate electrons emitted from the
photocathode towards the output screen.
•The anode has a +ve potential of 25 to 35 kv relative to the
photocathode, so it accelerates electrons to a tremendous
velocity.
OUTPUT PHOSPHOR:
•The output fluorescent screen of image intensifiers is silver
activated zn-cd sulfide.
•Crystal size and layer thickness are reduced to maintain
resolution in the minified image.
•A thin layer of aluminum is plated onto the fluorescent screen
prevent light from moving retrograde through the tube &
activating the photocathode.

16. Output Phosphor
 The glass tube of the image intensifier is abt 2 to 4mm
thick &is enclosed in a lead lined metal container
protects the operator from stray radiation.
 The output phosphor image is viewed either directly
through a series of lenses and mirrors or indirectly
through closed circuit TV.