Radiographic Imaging (3)

Question 1

What are the two radiographic imaging methods?

Answer 1

• filmless

- permanent

Question 2

List the three early methods of filmless radiography:

Answer 2

• Fluoroscopy
• Electronic Fluoroscopy
• Xeroradiography

Question 3

List the three types of permanent radiography:

Answer 3

• Photographic films and screens
• Fluorescent and Phosphorescent imaging plates
• Direct Digital and Computed

Question 4

Fluoroscopy

Answer 4

Examined by direct observation of the fluorescent screen, using shielded cabinets.
- viewed from the backside of the screen or mirror

Question 5

Electronic Fluoroscopy

Answer 5

Fluoroscopy with increased brightness and definition, increased safety, viewed on a close-circuit television

Question 6

Xeroradiography

Answer 6

Photocopy machine like, selenium coated electro-statically charged plate, produced when the charge was depleted and a developing powder was applied to an imaging paper.

Question 7

Photographic films and screens

Answer 7

viewed as photonegative, transparent polyester material coated with emulsion that is light sensitive, used with screens to aid in image formation.
- film is sandwiched between screens

Question 8

Types of screens

Answer 8

• lead
• fluorescent
• fluoro-metallic

Question 9

Intensification factor of lead screens

Answer 9

2-3

Question 10

Effects of lead screens (3)

Answer 10

• increases photographic action, electrons emitted and secondary radiation generated in lead
• absorb longer wavelengths
• intensify primary radiation

Question 11

Alloys for lead screens

Answer 11

6% antimony and 94% lead, providing better wear and abrasion resistance.

Question 12

Use of lead screens below ___kV may actually provide an image quality reduction and overall poor contrast

Answer 12

150kV

Question 13

When not using screens at voltages above 150kV image may appear to be ____.

Answer 13

mottled

Question 14

Fluorescent screens

Answer 14

Also referred to as Fluorescent salt-screens made of finely powdered or crystallized phosphor crystals miked with a binder to form a coating.
- absorb radiation and immediately emit light

Question 15

Intensification factor for Fluorescent screens

Answer 15

10-200

Question 16

Why aren’t Fluorescent screens used often?

Answer 16

produce a screen mottle, softer outline and graininess due to non-uniform distribution of light

Question 17

Fluorescent screens should not be exposed to the ____ _____ of primary radiation.

Answer 17

Full intensity of the primary radiation, the tend to develop and afterglow or become discoloured.

Question 18

Fluoro-metallic Screens

Answer 18

Middle ground between lead and fluorescent.

lead foil coated with phosphor

Question 19

Intensification factor of Fluoro-Metallic screens

Answer 19

5-150

Question 20

Screens for high energy radiation

Answer 20

energy ranges greater than 1MeV use copper or steel screens.
Linear accelerators 5-8MeV use thick copper screens.

Question 21

Digital Radiography

Answer 21

Filmless

flat curved panels constructed of micro-electric sensors or phosphor screens

Question 22

Benefits of Digital Radiography

Answer 22

• requires less radiation for image generation
• images can be enhanced digitally
• easy to save and share
• instantaneous
• built in recognition programs
• use panels repeatedly

Question 23

Flat panel detectors are referred to as:

Answer 23

Digital Detector Arrays (DDA’s)

• Complementary metal-oxide-semiconductor
• Linear diode arrays
• Amorphous selenium flat panel
• Amorphous silicon flat panel

Question 24

What are DDA’s

Answer 24

Electronic devices that convert radiation into an array of analog signals, digitalized and transferred to a computer display.

radiation penetrates into an electronic signal, converted into visible light, converts light into an electronic charge, photodiode signifies as pixel digitally read by low-noise electronics.

Question 25

Computed Radiography

Answer 25

Flexible phosphor imaging plate used with a laser scanning device for image processing.

• plate is flexible, placing an a standard film cassette, utilized similarly
• phosphors when exposed absorb radiation, scanned by a laser to make phosphors emit blue light, which is collected by a photomultiplier, amplified and digitalized for a computer (photo-stimulated luminescence)