Screen Film Radiography

Question 1

Radiographic film consist of two parts, what are they?

Answer 1

Base and Emulsion

Question 2

What is the name of a film coated on both sides?

Answer 2

Double emulsion film

Question 3

The base of consist of what type of structure?

Answer 3

Polyester

Question 4

The principle function of gelatin?

Answer 4

to provide mechanical support for silver halide crystals by holding them in a uniform place.

Question 5

98% of the emulsion is made up of?

Answer 5

silver bromide. The other 2% is made from silver iodide.

Question 6

What is a sensitivity center?

Answer 6

Photoelectrons and silver ions are attracted to these centers to form a latent image.

Question 7

The difference between high contrast versus low contrast films

Answer 7

high contrast emulsion contains smaller silver halide grains with uniform grain size. low contrast emulsion contain large grains with wider ranges of sizes.

Question 8

To optimize speed, the screen films are double emulsion, why?

Answer 8

Primarily to increase efficiency by using the two screens to expose the film on both sides.

Question 9

The purpose of a crossover control layer?

Answer 9

to reduce the blurring of an image and absorbs most of the crossover light

Question 10

Difference between orthochromatic and panchromatic films?

Answer 10

orthochromatic responds to green-sensitive films while panchromatic films are sensitive to all visible light spectrum.

Question 11

Red filter (light) are suitable for what?

Answer 11

for both green and blue sensitive films. Mainly used in dark rooms.

Question 12

Improper handling and storage results in?

Answer 12

poor radiographs with artifacts

Question 13

High amounts of heat and humidity will do what to the radiographs?

Answer 13

Increase fogging and lower contrast.

Question 14

What happens when light is exposed to the emulsion before processing?

Answer 14

Low-levels of light will produce fogging. High-levels of light will produce artifacts.

Question 15

How does excesses amount of scatter radiation affects the film?

Answer 15

Increases fog and reduces contrast.

Question 16

True or False. After exposure no image can e observed on the film only a latent image exist.

Answer 16

True

Question 17

Where is the greatest concentration of silver bromide and iodide found?

Answer 17

along the surface of the crystal

Question 18

Where does the electron migrate after exposure is taken?

Answer 18

towards the sensitivity center. (e- becomes trapped and forms metallic silver.

Question 19

What is the purpose of intensifying screen?

Answer 19

Coverts x-ray beam into visible light. Visible light interacts with the visible light to form the latent image.

Question 20

What is the name of the layer closet to the radiographic film?

Answer 20

protective coating. About 10 to 20 um thick and designed to help the screen to become more resistant to damages from handling.

Question 21

The layer within the intensifying screen responsible for emitting light?

Answer 21

Phosphor. Mostly made from gadolinium, lanthaunm, and yttrium.

Question 22

Why is the phosphor layer made from rare earth metals?

Answer 22

Lowers patient dose, less thermal stress on the x-ray tube, and reduces shielding for ex-ray rooms.

Question 23

What is the purpose of a reflective layer?

Answer 23

reflective light is intercepted and is redirected back towards the film

Question 24

What is the base designed for?

Answer 24

Serves has support for the phosphor layer. Made out of polyester or cellulose triacetate

Question 25

How does luminescence work?

Answer 25

Outer shell electron is excited x-ray beam, This causes e- to leave the shell creating a hole. When another e- fills that gap, a light photon is created.

Question 26

What is the difference between fluorescence and phosphorescence?

Answer 26

a fluorescence material will glow while the phosphor is stimulated. a phosphorescence will continue to emit light after stimulation has ended.(Causes screen lag or afterglow)

Question 27

A relative number that describes how efficiently x-rays and converted into light.

Answer 27

screen speed

Question 28

The effecting factors of screen speed

Answer 28

it increases phosphor size, thickness of layer, concentration. *Increasing the temperature decreases the screen speed.*

Question 29

Name the phases for producing a manifested image.

Answer 29

wetting, developing, fixing, washing/drying.

Question 30

the purpose of a developer?

Answer 30

to change the silver ions of exposed crystals into metallic silver.

Question 31

what is the difference between reduction and oxidation?

Answer 31

reduction moves a e-. oxidation adds an e-

Question 32

a reducing agent, produces shades of gray rapidly

Answer 32

Phenidone

Question 33

a reducing agent, produces black tones slowly

Answer 33

Hydroquinone

Question 34

What is the role of sodium carbonate?

Answer 34

controls the concentration of hydrogen ions (pH levels). helps with gelatin swelling. *Extremely corrosive and can burn skin*

Question 35

A chemical that restricts the developing agent to only silver halide crystals. Also controls the fogging of a image.

Answer 35

potassium bromide

Question 36

What does a preservative do?

Answer 36

controls the oxidation of the developing agent by the air. Hydroquinone is sensitive to aerial oxidation. Uses sodium sulfite.

Question 37

What controls the swelling and soften the emulsion?

Answer 37

a hardener agent. *Glutaraldehyde*

Question 38

what removes the impurities from the developing agent?

Answer 38

Chelates