Cassette and type

1. CASSETTE,
TYPES OF
CASSETTE AND
INTENSIFYING
SCREEN

2. CASSETTE
• Cassette is a flat, light-tight metal container which is designed
to hold the X-ray film and intensifying screen.
• Cassette is used in conventional and computed radiography for
the screen film system and imaging plate respectively

3. CONSTRUCTION
OF CASSETTE

4. • Cassette consist of front and back hinged at one edge.
• The front side of the cassette also referred to as Cassette
wall.
• It contains front intensifying screen and short lead
blocker used for patient identification.
• The front side is made up of low atomic number
material. Eg: Plastic or Carbon.

5. • The front side absorbs only 50% of X-rays compared
to aluminium.
• The back side of the Cassette is made up of high
atomic number. Eg:Lead
• It minimize the back scatter.
• Thin sheet of lead foil is attached on the backside
which is further attached to a plastic foam pad and an
intensifying screen

6. FEATURES
OF
CASSETTE
• Lightweight to facilitate easy
handling and caring.
• Easy to open and close under low
light condition.
• Uniform contact and between film
and screen by the use of foam
sponges
• Availabilty in various types with
respect to film size.

7. FUNCTIONS
OF
CASSETTE
• Cassette helps to hold intensifying
screen and protect them from damage.
• It exclude all light from entering the
Cassette.
• It maintains a close and uniform
contact between the film and screen.

8. TYPES OF
CASSETTE
• Single screen cassette
• Double screen cassette
• Curved cassette
• Gridded cassette
• Multisection cassette
• Vaccuum cassette
• Formatter cassette
• Angiography cassette
• Computed radiography cassette

9. SINGLE SCREEN CASSETTE
• It have a single intensifying
screen.
• These cassettes are designed to be
used with single sided emulsion
film
• The principle application of this
cassette is mammography

10. DOUBLE SCREEN CASSETTE
• Double screen cassette have screen
both sides
• It used with double sided emulsion
film
• It is used in general radiogrphy

11. CURVED CASSETE
• Curved cassette is Internally constructed
as conventional cassette with double sided
intensifying screen.
• The shape of the cassette is curved to
provide good contact between object and
cassette.
• This cassette is used in panoramic views
of mandible (OPG)

12. GRIDDED CASSETTE
• Gridded cassette have a secondary radiation
grid between the front intensifying screen
and the front side of cassette.
• It is used for radiography where
conventional bucky system unavailable.
Eg:wardradiography

13. MULTISECTION
CASSETTE
• Multisection cassette is designed to hold 3-7
films with their respective intensifying screen
and spacers of about 5or10mm in thickness.
ADVANTAGE OF USING SPACERS
• Films which are separated by 5mm spacers
will produce images of body sections 5mm
apart and like wise 10mm spacers
• Multisection cassette is used in multiple
radiography

14. VACUUM CASSETTE
• Vacuum cassette is made up of flexible vinyl material.
• Have a valve,attached at one end.
• Inside the cassette is removable plastic folder containing
single intensifying screen.
• Single sided emulsion film is inserted inside the folder.
• The entire fold is placed inside the cassetteand sealed.
• Vacuum pump is attached to the valve and air expelled
thus bringing the intensifying screen and film in close
contact
• It is used in jointradiography

15. FORMATTER CASSETTE
• Formatter cassette is designed to hold two single sided
emulsion films by their edges
• Also consists of two removable slides whichprotect the
film from light exposure when not in use.
• Do not contain intensifying screens.
• Formatter cassette is used in CT,MRI,DSA.

16. ANGIOGRAPHY CASSETTE
• Can hold upto 30 sheets of film size 35*35 cm
each positioned with metal spacers.
• After loading and sliding the two panels the
cassette can be inserted into the AOT equipment.
• Exposed films will have been transferred via
exposure areas of AOT apparatus to the take up
cassette.
• A button on the front is pressed closing the sliding
lid.
• Take up cassette then be taken to darkroom and
processed.

17. COMPUTED RADIOGRAPHY CASSETTE
• Imaging plates in place of film and screen.
• The plates are coated with europium
activated by Barium Fluoro Halide.
• Information is stored in the imaging plates
as electrons.
• Image information is acquired by scanning
the plate by laser beam.

18. INTENSIFYING
SCREEN

19. • What is an intensifying screen?
• It is a part of cassette which converts xray energy into visible
light.
• It reduces patient dose and also increases the radiographic
contrast.
• Itensifying screen consists of four layers namely
 BASE
 REFLECTING LAYER
 PHOSPHOR
 PROTECTIVE COAT

20. BASE
• The base is made up of polyester of 1mm thickness.
• The base serves as a support on which the reflecting
layer, phosphor, protectivelayer are mounted.
• The base material should be moisture free ,resistance
to radiation damage,flexible.

21. REFLECTING LAYER
• The reflecting layer is in between the phosphor and the base.
• It is made up of white substance such as titanium dioxide or
magnesium oxide.
• Thickness of 25
• Reflects the light towards the phosphor and also increases the
efficiency of screen.

22. PHOSPHOR
• Active layer of screen.
• Which emits light when exposed by xrays.
• Thickness of the phosphor 150-300
• Commonly used phosphors are calcium tungstate, zinc
cadmium sulfide, cesium iodide.
• Rare earth phosphors are gadolinium oxysulfide,lanthanum
oxysulfide,lanthanum oxybromide,yuttrium tantalate.
• Their absorption and conversion efficiencyis high.

23. PROTECTIVE COAT
• This is the closest layer of intensifying screen to the film.
• Considered to be transparent layer.
• Thickness of layer is 15-25
• It is resistant to abrasion and damage caused by handling.
• Thickness of the intensifying screen is about 1.15-1.3mm.