Fluroscpic imaging

1. Fluroscopic Imaging
Image Intensifier Design
Vidicon & CCD Camera
BY- Ruta Satoskar.

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. 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.

11. 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.

12. 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.

13. AACCCCEELLEERRAATTIINNGG AANNOODDEE ::
•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.
OOUUTTPPUUTT PPHHOOSSPPHHOORR::
•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.

14. Output Phosphor contd.
 A thin layer of aluminum is plated onto the fluorescent
screen prevent light from moving retrograde
through the tube & activating the photocathode.
 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.