Lecture 4 conventional radiography

Question 1

Cassette ?

Answer 1

Light proof holder for the film
Front side : Facing the x ray source
made of plastic with low atomic number

Back side : made of heavy metal , minimize backscatter radiation

Question 2

What to maintain the close contact when the cassette closed ?

Answer 2

Compression device such as felt or rubber use

Question 3

what is an Intensifying screen ?

Answer 3

It is increase the efficiency of x-ray absorption and decrease the dose to the patient

Depending on the phosphor used, the screen will emit light in the blue or green spectrum

Question 4

4 layers of intensifying screen construction ?

Answer 4

Protective coating : Layer closest to film
about 10 - 20 micrometers thick

Phosphor layer : Active layer and emits light

Reflective layer : redirects the light to film ( 25 micro meters)

Base : Provides support , Farthest from film (1mm thickness) ( it is flexible)

Question 5

Made of reflective material “magnesium oxide or titanium dioxide” and redirects the light from the phosphor toward the film ”increasing the efficiency of the intensifying screen is ?

Answer 5

Reflective layer

Question 6

Made up of crystals embedded in a clear plastic support layer
and It convert incident x-ray photons into visible light photons ( active layer)?

Answer 6

Phosphor layer

Question 7

It is advice used to reduce the level of scatter radiation reaching the image receptor is
or
whose direction is on straight line from source to image receptor is ?

Answer 7

Grid ( which improves image quality)

Question 8

2 components of Grid ?

Answer 8

Lead strips (grid material)
Aluminum strips (interspace material)

Question 9

2 types of Grid ?

Answer 9

Stationary
Moving (grid is moving while x ray exposure is being made)

Question 10

Film construction ?

Answer 10

Consist of two parts: base and emulsion
Most of x-ray film are double emulsion.

Question 11

Provides a surface and support for the emulsion , It must have strength, but be flexible
Most film bases are composed of polyester
It can tolerate higher temperatures and more fireproof is ?

Answer 11

Transparent base

Question 12

Glue emulsion to the base
To ensure uniform adhesion of the emulsion to the base and
allows the emulsion and base to maintain proper contact during processing is ?

Answer 12

Adhesive layer

Question 13

Consist of homogenous mixture of gelatin and silver halide crystal
The gelatin acts as a suspension agent and prevents the crystals from adhering to one another also ( active layer) is?

Answer 13

Emulsion layer

Question 14

Has designed to be sensitive to different wavelengths is ?

Answer 14

Emulsion layer
Blue sensitive also called panchromatic
green- sensitive also called orthochromatic

Question 15

Protect the emulsion from scratches, pressure and contamination is ?

Answer 15

Overcoat layer ( protective layer)

Question 16

What is latent image formation ?

Answer 16

When the image is not visible

The Gurney-Mott theory says that X-rays and light ionize atoms in a crystal that Free electrons move to a sensitivity speck attracting silver ions (Ag+)

Question 17

what creates latent image ?

Answer 17

When silver atoms gather at the sensitivity speck, the crystal’s charge changes
and
Pattern of exposed and unexposed crystals in undeveloped film formed by how the patient absorbs radiation

Question 18

What makes radiographic image visible ?

Answer 18

Developing turns silver ions in exposed crystals into black metallic silver

Question 19

Film speed ?

Answer 19

The speed of an X-ray film is its ability to respond to exposure, determined by its sensitivity

which depends on the size of silver halide crystals, the number of sensitivity specks, and the thickness of the emulsion

Larger crystals, more specks, and thicker emulsion increase the film’s speed

Question 20

Types of Film ?

Answer 20

All specialty films are single-emulsion

It provides better resolution than double-emulsion film

Mammographic Film

Duplication Film: designed to be sensitive to ultraviolet (UV) light from the duplicating machine

Question 21

What provides better resolution ?

Answer 21

Single - Emulsion film

Question 22

It is the mark or spurious image that sometimes appear on the processed film is ?

Answer 22

Artifact

Question 23

Radiographic film is sensitive to ?

Answer 23

heat and humidity ( Heat reduce the contrast and increase fog and decrease the image contrast )

Light ( should handled in dark , if low level light exposes the film fog increased )

Radiation ( Ionization radiation other than useful beam create artifact by reducing contrast and increasing fog )

Question 24

Safe lights ?

Answer 24

For blue-sensitive film, an amber filter (transmitting light above 550 nm) is used

For green-sensitive film, a red filter (transmitting above 600 nm) is needed to prevent fogging

Question 25

How to process automatic film processing ?

Answer 25

Turns the invisible latent image into a permanent visible one by reducing silver ions in exposed crystals to black metallic silver

The silver appears black due to its tiny crystal size scattering light ( instead of reflecting it )

Processing involves four essential stages: developing, fixing, washing, and drying, to create a diagnostic-quality radiograph

Question 26

Developing ?

Answer 26

Is a water-based chemical solution that reduces exposed silver halide crystals to metallic silver while leaving unexposed crystals unchanged

It uses phenindione and hydroquinone:

Activator: Keeps the developer alkaline.
Restrainer: Limits the reducing agent’s action
Preservative: Prevents oxidation of reducing agents.
Hardener: Maintains gelatin thickness and hardens the emulsion; lack of it causes soft, moist films.
Solvent: Dissolves chemicals, usually filtered water

Question 27

What agents uses quickly enhancing fine details and gray shades but not heavily exposed areas ?

Answer 27

Phenindione

Question 28

What agent acts slowly, creating dark, dense areas ?

Answer 28

Hydroquinone

Question 29

Fixing ?

Answer 29

The fixer stops the developer’s action and removes unexposed silver halide crystals, preparing the film for archiving

Also known as clearing agent : ammonium thiosulfate, ensures the film is clear and durable

If not fully removed, the film appears milky and won’t last under archival conditions
Other chemicals aid in the fixation process

Activator:
Acetic acid maintains the pH to enhance the clearing agent
Preservative:
Dissolves silver from the ammonium thiosulfate
Hardener:
Prevents scratches and abrasions/cuts during processing
Solvent:
Dissolves other chemicals

Question 30

Washing ?

Answer 30

The washing stage removes any remaining chemicals

If developer or fixer is left, it can oxidize and turn the film brown

Clean water is continuously circulated to ensure thorough washing

Unremoved fixer can react with metallic silver, causing stains like silver sulfide or dichroitic stains (hypo retention)