fluoroscopy refrence:\ bushong

1. Reference book:
Stewart C.bushong
BByy HHuuzzaaiiffaa AAttiiqquuee
SSiirr SSyyeedd UUnniivveerrssiittyy ooff EEnnggiinneeeerriinngg && TTeecchhnnoollooggyy

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. 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.  11sstt GGeenneerraattiioonn IImmaaggee IInntteennssiiffiieerrss
Input phosphor - Zinc Cadmium Sulfide
Output phosphor - Zinc Cadmium Sulfide.
 22nndd GGeenneerraattiioonn IImmaaggee IInntteennssiiffiieerrss
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 cceessiiuumm aanndd aannttiimmoonnyy ccoommppoouunnddss,
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.

13.  The principal advantage of image-intensified
fluoroscopy over earlier types of fluoroscopy is
increased image brightness.
IImmaaggee mmoonniittoorriinngg::
 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.

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