fluorosopy power point presentation

1. Reference book:
Stewart C.bushong
By Huzaifa Atique
Sir Syed University of Engineering & Technology

2.  The primary function of a fluoroscope is to perform
dynamic studies; that is, the fluoroscope is used to
visualize the motion of internal structures and fluids.
 The purpose of this technique is to get real-time and
moving images of the insides of a person by way of
the fluoroscope.
 If something is observed that the radiologist would
like to preserve for later study, a radiograph can be
made with little interruption of fluoroscopic
examination. Such a radiograph is known as spot
film.

3.  Visualization of vessels is called
Angiography.
 The two main areas of angiography are:
 Neuroradiology
Vascular Radiology.
 And with all this procedure spot films are
obtained.
 During fluoroscopy the x-Ray tube is
operated at less than 5mA. Normally 2 to
4mA.

4. Components of
Fluoroscope
x-ray generator
 x-ray tube
 collimator
 filters
 patient table
 grid
 image intensifier
 optical coupling
television system
image recording

5.  The image intensifier is a complex electronic device
that receives the remnant X-Ray beam, converts it
into light, and increases the light intensity.

6. Glass envelope
Input phosphor
Photocathode
Electrostatic focusing lenses
Output phosphor

7. Glass envelope:
Maintains tube vacuum to allow control of e
flow, has no functional part in image formation.
Input phosphor:
X-Rays that exit the patient and are incident on
the image intensifier tube are transmitted
through the glass envelope and interact with
the input phosphor, which is cesium iodide.
When X-Rays interacts with the input
phosphor, its energy is converted into a burst of
visible light photons as occur on the
intensifying screen.

8. 1st Generation Image Intensifiers
Input phosphor - Zinc Cadmium Sulfide
Output phosphor - Zinc Cadmium Sulfide.
2nd Generation Image Intensifiers
Input phosphor- Cesium Iodide (smaller
crystals with greater packing density -
manmade)
Output phosphor - Zinc Cadmium Sulfide.

9. Photocathode:
It is bonded directly to the input phosphor with a
thin, transparent, adhesive layer.
The photocathode is a thin metal layer, usually
composed of cesium and antimony compounds,
that respond to stimulation by light with the
emission of electron. This process is known as
photoemission.

10. Located along length of the tube, responsible
for focusing the electrons across the tube from
input to output phosphor. Image is reversed
from input to output phosphor (right becomes
left, superior to inferior). The concave input
screen reduces distortion by keeping the same
distance between all points on the input &
output screens.

11. Anode is usually charged with 25 kV and is
used to accelerate e across the tube (not a
target) to > kinetic energy & > light produced.
Collects stray e as well.
The output phosphor is usually made up of zinc
cadmium sulfide crystals. Each photoelectron that
arrives at the output phosphor results in
approximately 50-70times

13. The principal advantage of image-intensified
fluoroscopy over earlier types of fluoroscopy is
increased image brightness.
Image monitoring:
Two methods are used to electronically convert
the visible image on the output phosphor of the
image intensifier into an electronic signal.
1. Thermionic television camera tube
2. The solid state charge-coupled device
(CCD).

15. The television camera consists of cylindrical
housing, approximately 15 mm in diameter by
25 cm in length, that contains the heart of the
camera, TV camera tube.
It also contains electromagnetic coils that are
used to properly steer the electron beam inside
the tube.
A number of such television camera tubes are
available for television fluoroscopy, but the
vidicon and its modified version, the
Plumbicon, are used most often.

17. Two methods are commonly used to couple the
television camera tube to the image-intensifier tube.
Fiber optics.
Lens system.
The simplest method is to use a bundle of fiber
optics.
One advantage of this type of coupling is its
compact assembly, which makes it easy to move the
image-intensifier tower. This coupling is rugged and
can withstand relatively rough handling.
The principal disadvantage is that it cannot
accommodate the additional optics required for
devices such as cine or photospot cameras.

18. To accept a cine or photospot camera, lens
coupling is required. This type of coupling
results in a much larger assembly that should
be handled with care.
The objective lens accepts light from the output
phosphor and converts it into a parallel beam.
When an image is recorded on film, this beam
is interrupted by a beam-splitting mirror so that
only a portion is transmitted to the television
camera; the remainder is reflected to a film
camera. Such a system allows the
fluoroscopist to view the image while it is being
recorded.

20. The video signal is amplified and is transmitted
by cable to the television monitor, where it is
transformed back into a visible image.