The basic principles of the photographic process and the factors that affect the sensitivity of ... Film performs several functions in the medical imaging process.

1. PRESENTEDBY:SAKSHI KUMARI
Secondyear: BSCIN MEDICAL
TECHNOLOGYIN RADIOLOGY

2.  Some chemical compound undergo subtle
structural changes when exposed to
EMR(visible light,uv radiation or xray
),these changes are not immediately
visible rather is visible after certain
chemical reaction,exposed material
respond differently from unexposed
material,this chemical nature of material
is known as photographic effect.
 The chemical reaction needed to make
invisible image visible is photographic
development.

3.  Silver halides-have regular 3d or lattice
structure.
 Like common salt they also have ionic bond.
 Chemical properties;relatively stabledont
suffer from chemical breakdown. But if
reducing agent used can be converted into
metallic silver.
 Therefore we can say that photographic
development is a chemical reduction.

4.  Invisible structural changes occur.
 Case 1-xray photon emerges from the crystal
unscathed-no change occus in crystal
structure.
 Case 2-xray photon gets absorbed and causes
electron release as a result of interaction
with bromine.
 Free electron gets lodged in low energy
elcetron trap near surface of crystal as
sensetivity speck and the latter is produced
by the intoduction of impurity.

5.  An invisible image fromed from exposure of
radiation .
 Latent image becomes visible image upon
photographic development.
 Gurney mott theory and mitchell theory to
explain latent image.

6.  Silver halide
 React with fixing
agent and form
soluble compound
 Not opaque
 Sensetive to light
 Metallic silver
 Unaffected
 Opaque
 Insensetive to light

7.  Emulsion is microscopic crystal of silver
halide in gelatin.
 Coated onto a supporting later of
transparent plastic known as base.
 Gelatin – liquid or solid gelly,act as
suspending media and binding agent for
silver halide.
 Transpent ,clumping,penetrating agentuniformityholding
capability,unreactive are properties of gelatin.

8.  Image produced as aresult of exposure to
light.
 To ensure efficient absorption;
 (1)close packing of silver halide grain.
 (2)increase the size of halide grain.
 (3)increase the thickness of emulsion layer.
 (4)Modifying the shape of halide grain.

9.  Most common type of film in xray department.
 Both sided emulsion and both sided intensifying
screen.Two image produces as a result of
exposure from both sides but base is thin sp both
image are
 Advantage ;
 Increased sensetivity and identical.increased
image contrast,
 Disadvantage ;
 Loss of image quality and economic reasons.
identical.increased image contrat

10.  In this emulsion emulsion side is coated only
to one side of its base with one intensifying
screen.
 They must only be loadedinto a cassette with
their emulsion side in contact
withintensifying screen ,manufacturer cuts a
small notch onto one edge of each film.

11.  Image are produced as a result of direct xray
exposureno longer used in departments but
in intra oral dental radiography and in
foreign body detection it is still used.
 Its design features;
 Duplitization-to gain the benefit of maximum
film emulsion.
 Sensitizers-enable additional sensitivity to
direct xray exposure.