Intro & Physics

Question 1

What are x-rays?

Answer 1

a type of electromagnetic radiation

Question 2

What is the other word for Photon?

Answer 2

X-rays

Question 3

What are the properties of x-rays?

Answer 3

No charge or mass
Invisible 
Cannot be felt 
Travel at speed of light 
Penetrate all matter to some degree 
Cause ionization if energy high enough

Question 4

Ionization

Answer 4

loss of an electron

Question 5

ALARA

Answer 5

As Low As Reasonably Achievable

Question 6

What is included in the time component of ALARA?

Answer 6

Rotate personnel in the room
Avoid repeat examinations
Minimize patient holding

Question 7

What is included in the distance component of ALARA?

Answer 7

Increasing distance between personnel and radiation source reduces exposure significantly

Question 8

Inverse Square Law

Answer 8

intensity of radiation decreased with the square of the distance from the source
Doubling the distance reduces the x ray intensity to 1/4th(1/2)^2
Tripling the distance reduces the x ray intensity to 1/9th(1/3)^2

Question 9

How do you reduce scatter?

Answer 9

Minimize the size of the beam

Question 10

Radiograph

Answer 10

A picture of the pattern of x rays emerging from the patient

Question 11

What controls the number of x rays produced and proportional?

Answer 11

current (mA) and time the current is “on” (s)

Question 12

mA

Answer 12

controls the current that goes through the filament and the hotter the filament gets the more electrons are generated

Question 13

What controls the number of electrons produced?

Answer 13

how long the current is left on

Question 14

Milliampere (mA)

Answer 14

Number of electrons at cathode is proportional to mA

Question 15

Seconds

Answer 15

longer time = more electrons produced

Question 16

Increasing kVp

Answer 16

Greater voltage difference
Electrons travel faster
Have more kinetic energy
Create higher energy x rays

Question 17

Underexposed radiograph

Answer 17

too Light

Question 18

Overexposed radiograph

Answer 18

too dark

Question 19

How do you fix an underexposed radiograph?

Answer 19

Increase mAs
or
Increase kVp

Question 20

Increasing mAs

Answer 20

Increased number of x rays that strike patient

Question 21

Increasing kVp

Answer 21

x rays have higher energy

Question 22

Thorax Radiographs

Answer 22

Air provides contrast

Use high kVp, low mAs

Question 23

Abdomen Radiographs

Answer 23

Fat provides contrast

Use low kVp, high mAs

Question 24

When are grids used?

Answer 24

used when patient is more than 10 cm thick

Question 25

What is the purpose of the Grid?

Answer 25

intercepts scatter from patient before it reaches film

Question 26

What is the intensifying screen used for?

Answer 26

converts x-ray photon to light photons

Question 27

What are the advantages to using an intensifying screen?

Answer 27

Permit over 100x reduction in mAs compared to no screens
Reduced movement artifact 
Reduced patient exposure
Reduced personnel exposure 
Increased tube life