An image-recoding process in which the sensitive
material is a plate carrying an electrical charge on its
surface. When light falls on the surface the charge is
released. The plate is dusted with a special powder
and image is formed by the powder being attracted
and retained in charged area.
Xeroradiography is not a process requiring any
specialized x-ray equipment; it is only a different
method of recording an x-ray image.
It depends upon the photoconductive behaviour of a
selenium plate and substitutes a photoelectric process
for photochemical one associated with the use of a
Is an insulator in the dark, become conductive when
exposed to light or x-ray.
If the plate is given a superficial electric charge, it is
capable of remaining of retaining this charge for a
period of hours.
In charged condition, expos of the plate to light or xrays effect conduction in exposed area.
Two machines are necessary for xergraphy
The main features of the conditioner
A – a storage box containing xergraphic plate.
B, C- a plate (B) passes form storage box through
a small oven (C) which removes any residual
charge; the plate then to storage elevator (D).
E- insertion of an empty cassette initiates the
F- an ionizing device which charges the surface of
the plate after it leaves the storage elevator and
before it enters the open cassette.
•I – a rotating brush which cleans the plate
before H- a third ionizing device which loosens
any powder remaining on the plate after
it enters a storage box.
•J – the paper passes through an oven (J)
which fuses the power image to the paper
The main features of the processor for xergraphy
A- the cassette containing the exposed plate.
B- the plate is transported to a development chamber,
where developer powder (toner) is sprayed on its surface.
C- D paper is removed from the paper tray (C) to a
position (D) for contact with powder plate.
F- an ion- emitting device, the effect of which is
to loosen the powder on the plate, preparatory to
G- another ionizing device which gives the
reverse side of the paper a charge of opposite
To copy radiograph is produce a second from the
It may be
Smaller in size than the first (miniaturized)
The same size (facsimiles)
large in size (enlargement)
Duplicate film (copy film):
Is single emulsion film that is exposed to ultraviolet
light or blue light through existing radiograph to
produce a copy.
Duplicate film is direct positive film.
Used in angiography, although with the increasing
application of digital fluoroscopy, its use is declining.
Subtraction film single emulsion, and there are
generally two types;
(a) One type to prepare the subtraction mask.
(b) One to accommodates the superimposed image of
the original radiograph and subtraction mask.
Subtraction film has high contrast to enhance
existing subject contrast
Digital subtraction angiography
Digital imaging technology (cont)
The technique of digital subtraction
angiography (DSA), based on digital
image processing, allows enhanced
visualization of blood vessels by
electronically subtracting unwanted
parts of the image.