Principles of Radiology

Question 1

What are x-rays? Examples? (4)

Answer 1

1. A form of electromagnetic radiation
2. Examples:
   - Gamma rays
   - Radio waves
   - Visible light
   - TV waves

Question 2

What is a radiograph?

Answer 2

An image produced on film due to x-rays

Question 3

How do electromagnetic waves move?

Answer 3

In an X & Y axis

Question 4

T/F: X-rays have a shorter wavelength than visible light, therefore they can penetrate object when visible light is reflected or absorbed

Answer 4

True

Question 5

What is it in X-rays that allows certain materials to fluoresce?

Answer 5

Photons do this, they cause “excitement.”
Therefore, we can record images

Question 6

T/F: Light and X-rays act like waves traveling thru space

Answer 6

True

Question 7

T/F: Light and X-rays act like particles when interacting with matter

Answer 7

True

Question 8

T/F: Light and X-rays don’t travel in straight lines

Answer 8

False. They don’t, therefore, they cannot go around corners

Question 9

T/F: Light and X-rays diverge from a point source

Answer 9

True

Question 10

T/F: X-rays are affected by magnetic fields

Answer 10

False! They are NOT affect by magnetic fields

Question 11

T/F: X-rays travel at the speed of light

Answer 11

True

Question 12

Where do X-rays come from? How does it work?

Answer 12

1. An x-ray tube!
2. How it works:
   - Fast moving electrons hit a metal target
   - 99% of energy is converted to heat
   - 1% of energy is converted to x-rays

Question 13

Basic parts of the x-ray tube (4)

Answer 13

1. Air evacuated glass chamber
2. Cathode
3. Anode
4. Cooling mechanism

Question 14

Air evacuated glass chamber

Answer 14

Prevents electrons from colliding with air molecules

Question 15

Cathode
Source
How it works

Answer 15

1. Source of electrons
   - Negative end
2. 1-2 wire filaments within wells of focusing cup
   - Filaments are heated to critical temp and electrons are boiled off.
   These electrons are then accelerated toward the anode

Question 16

Anode

Answer 16

• Target for electrons from cathode
• Where x-rays are created
• Positive end

Question 17

Focal spot

Answer 17

• A small focal spot produces a more detailed image
• Small filaments produce limited number of electrons

Question 18

Effective focal spot

Answer 18

Angling the target a small degree will produce a small effective focal spot

Question 19

Heel effect

Answer 19

• Angled anode leads to more energy on cathode side of beam due to partial absorption of beam into anode.
• Therefore, one should place thicker body parts toward the cathode side of the beam to produce more uniform image

Question 20

T/F: One should place thicker body parts toward the cathode side of the beam to produce more uniform image due to the Heel Effect

Answer 20

True

Question 21

T/F: Cooling mechanisms are required in x-ray machines because filament may get as hot as 3000 F

Answer 21

True

Question 22

T/F: Stationary anode has a tungsten target embedded in block of copper. This design is used in dental & portable x-rays

Answer 22

True

Question 23

T/F: Rotating anode won’t dissipate heat and makes a larger focal spot. This will increase image detail

Answer 23

False.
It WILL dissipate heat and makes a SMALLER focal spot that will INCREASE image detail

Question 24

In regards to X-ray care, do not… (4)

Answer 24

1. Drop or hit xray tube
2. Leave machine on continuously
3. Hold down the rotor “ride the rotor”
4. Make too many high energy exposures in rapid succession

Question 25

T/F: X-rays can only make shadow images.
Small beam = sharp shadow
Large beam = fuzzy shadow

Answer 25

True!

Question 26

Rectifier definition

Answer 26

Changes AC to DC

Question 27

Grid definition

Answer 27

Absorbs some scatter

Question 28

Electron definition

Answer 28

Neg charged atomic particle

Question 29

Photon definition

Answer 29

Packet of energy

Question 30

Focal spot definition

Answer 30

Specific region on the target where the xray leaves to the world