Digital and Film Radiology

Question 1

What is the plate made from in digital X-Ray receptors?
How do these create the final image?

Answer 1

Phosphor Plate
After receptor is exposed to x-rays, it must be put in a scanner and read to create the final image

Question 2

What type of X-rays receptor can be used again?
What type can’t?

Answer 2

Digital receptors can be disinfected and used again
Film receptors can’t be used again as they become the image themselves

Question 3

What size of phosphor plate receptor is used for anterior periapicals?

Answer 3

Size 0

Question 4

What size of phosphor plate receptor is used for bitewings and posterior periapicals?

Answer 4

Size 2

Question 5

What size of phosphor plate receptor is used for occlusal radiographs?

Answer 5

Size 4

Question 6

What creates an X-Ray shadow?
What is it?

Answer 6

When the x-ray beam passes through an object some of the photons are attenuated which creates an x-ray shadow
The x-ray shadow is the image ‘information’ held by the x-ray photons after an x-ray beam has passed through an object
The image receptor detects this x-ray shadow & uses it to create an image

Question 7

What is the benefit of a higher number of pixels?

Answer 7

More pixels means better detail in the image and a higher resolution
Increasing the resolution will provide a more diagnostic image up to a limit (eventually it will not provide any meaningful clinical benefit)

Question 8

What does DICOM stand for?
What is it?

Answer 8

Digital Imaging & Communications in Medicine
International standard format for handling digital medical images (used to transmit, store, retrieve, print, process & display images)

Question 9

What is the SMPTE test pattern?
What is it used for?

Answer 9

Society of Motion Picture & Television Engineers
Can be used to assess the resolution, contrast & brightness of your monitor/monitors

Question 10

How is the image created in the patient’s mouth using phosphor plates?

Answer 10

Receptor is exposed to the x-ray beam
Phosphor crystals in receptor are excited by the x-ray energy, resulting in the creation of a latent image

Question 11

How is the image created within the scanner using phosphor plates?

Answer 11

Receptor is scanned by a laser
The laser energy causes the excited phosphor crystals to emit visible light
The light is detected & creates the digital image

Question 12

How does the phosphor plate receptor transfer the image to a computer?

Answer 12

Has to be wiped and disinfected and placed in a scanner

Question 13

How do solid-state sensors transfer the image to the computer?

Answer 13

Usually wired to the computer but can be wireless
Latent image created & immediately read within the sensor itself (final image is created virtually instantly)

Question 14

Where does the identification dot need to be placed when putting together an X-ray receptor?

Answer 14

In the top right hand corner

Question 15

What are the advantages of phosphor plates?

Answer 15

Thinner, lighter and more flexible
Wireless, more comfortable
Variable room light sensitivity & risk of impaired image (need to be in a dark box)
Latent image needs to be processed in scanner separately
Handling similar to film

Question 16

What are the advantages and disadvantages of solid-state sensors?

Answer 16

Bulkier and rigid
smaller active area (for same physical area of receptor)
more durable- replaced less often
no issues with room-light control
more expensive

Question 17

What is in an intra-oral film packet? (Used in film radiography)

Answer 17

Protective (black) paper
—Protects film from light exposure, damage by fingers and saliva
Outer wrapper
—prevents ingress of saliva
—indicates which side of the packet is the front
Lead Foil
—absorbs some excess x-ray photons

Question 18

What is a radiographic film? What photons is it sensitive to? How does this produce an image?

Answer 18

Material in which the actual image is formed
sensitive to both x-ray photons & visible light photons
photons interact with emulsion on film to produce latent image which only becomes visible after chemical processing

Question 19

What is in a radiographic film structure?

Answer 19

Transparent plastic base
Adhesive
Emulsion
Protective coating of clear gelatin

Question 20

What is the transparent plastic base for in radiographic film structure?

Answer 20

To support the emulsion

Question 21

What is the adhesive for in radiographic film structure?

Answer 21

Attaches the emulsion to the plastic base

Question 22

What is the emulsion for in radiographic film structure?

Answer 22

It is layered on both sides of the plastic base
Silver halide crystals embedded in a gelatin binder
Results in higher resolution than digital

Question 23

What is the protective coating of clear gelatin for in radiographic film structure?

Answer 23

Shields the emulsion from mechanical damage?

Question 24

How do the silver halide crystals produce an image in film radiography?

Answer 24

Become sensitised upon interaction with x-ray (& visible light) photons
During processing the sensitised crystals are converted to particles of black metallic silver (dark parts of final image)and the non-sensitised crystals are removed (light parts of the final image

Question 25

What is film speed? What happens if you increase speed

Answer 25

Relates to the amount of x-ray exposure required to produce an adequate image Increasing the speed decreases the radiation required to achieve an image It is also affected by the number & size of the silver halide crystals (larger crystals= faster film but poorer image quality)

Question 26

What must you do if changing to a different film speed?

Answer 26

Convert settings on x-ray unit (by a qualified technician) or Install a filter to absorb part of the primary x-ray beam

Question 27

What are intensifying screens?

Answer 27

Used alongside special indirect action film for extra-oral radiographs They reduce radiation dose but also reduce detail

Question 28

Why is film processing required for x-rays?

Answer 28

Converts the invisible latent image to a visible permanent image

Question 29

What are some common steps in Film processing? What does each step do?

Answer 29

Developing --converts sensitised crystals to black metallic silver particles Washing --removes residual developer solution Fixing --removes non sensitised crystals and hardens the emulsion Washing --removes residual fixer solution Drying --removes water so film is ready to be handled/stored

Question 30

What is involved in a manual (wet) processing cycle?

Answer 30

Person dips film into different tanks of chemicals at precise concentrations/temperatures for specific periods of time Washes the film after each tank Must be carried out in a dark room with light tightness and adequate ventilation

Question 31

What are the steps for opening a film packet for automated processing?

Answer 31

Disinfect the surface of the packet (&wipe off) Hold the packet under the hood of processor unit Peel back flap of outer wrapper Fold back lead foil Pull back paper flap Hold film by edges (not surfaces) and slide out Insert film into processor

Question 32

What are some developing issues during processing?

Answer 32

It involves a chemical reaction (between sensitised silver halide crystals and black silver) Reaction affected by time, temperature and solution concentration Developer solution oxidises in the air --Becomes less effective over time --Needs to be replaced regularly (irrespective to how many films have been developed)

Question 33

What are some fixing issues during processing?

Answer 33

Fixing involves a chemical reaction which removes non-sensitised crystals & hardens the remaining emulsion Inadequate fixing means non-sensitised crystals are left behind --makes the image green/yellow ish or milky --makes the image brown over time

Question 34

What can cause a pale image to be formed?

Answer 34

Exposure issue --radiation exposure factors too low Developing issue --film removed from solution too early --solution too cold --solution too dilute/old

Question 35

What are the advantages to digital radiography?

Answer 35

No need for chemical processing easy storage & archiving of images easy back-up of images images can be integrated into patient records easy transfer/sharing of images images can be manipulated