Chapter 5 Rad 2

Question 1

Scatter is the result of?

Answer 1

Compton

Question 2

What results from an interaction with an outer shell electron?

Answer 2

Compton

Question 3

What are the end results of compton?

Answer 3

Weakened X-ray photon, Gray on radiograph

Question 4

what is another name for Compton?

Answer 4

Recoil Electron

Question 5

2 factors affecting the amount of scatter reaching the IR

Answer 5

kVp & Volume of tissue

Question 6

Why does kVp and volume of tissue affect scatter?

Answer 6

the higher the kVp the more scatter, fatter scatter

Question 7

as collimation decreases (increased field size) what happens to scatter, patient dose, contrast, and density?

Answer 7

Scatter= increases , patient dose= increases, Contrast= decreases, Density increases

Question 8

as collimation increases (decreased field size) what happens to scatter, patient dose, contrast, and density?

Answer 8

Scatter= decreases , patient dose= decreases, Contrast - increases, Density= decreases

Question 9

What is the first step in patient protection?

Answer 9

optimum collimation

Question 10

significant collimation may require and increase or decrease in mAs?

Answer 10

increase (example L5-S1)

Question 11

There is ___ unsharpness on the anode side of the tube?

Answer 11

less

Question 12

There is ___ unsharpness on the cathode side?

Answer 12

more

Question 13

What is the simplest type of collimator. Piece of lead with a hole in it. Not variable, and not used very much.

Answer 13

aperture diaphragm

Question 14

What is shaped like a megaphone and correlates to divergence of the beam.

Answer 14

Cone

Question 15

What is shaped like a tube and can extend down, used mostly for skull work?

Answer 15

Cylinders

Question 16

Which is better cone or cylinder?

Answer 16

cylinder

Question 17

What is the best type of variable beam- restricting device? has 2 sets of adjustable lead shutters and a light source for centering?

Answer 17

Box Type collimator

Question 18

NCRP says collimation must be within __ of the SID

Answer 18

+/- 2 percent

Question 19

How can you check collimation?

Answer 19

9 penny test

Question 20

What years was it a law that all equipment manufactured had to have PBL installed?

Answer 20

8/1/1974-1994

Question 21

Who invented the stationary grid in 1913?

Answer 21

Gustave Bucky

Question 22

When do you use a grid?

Answer 22

when the part is 10cm or bigger & 60 kvp or above

Question 23

Grid ratio formula?

Answer 23

height of pb strips/ distance between pb strips

Question 24

Interspacing material can be Organic or Inorganic give examples of both

Answer 24

Organic= Carbon like balsa wood, cardboard 
Inorganic= Not Carbon like aluminum (usually used)

Question 25

Grid frequency

Answer 25

of Pb lines/ inch or cm

Question 26

how many PB lines are there usually?

Answer 26

60-110

Question 27

The higher the grid ratio the ___ the cleanup

Answer 27

more

Question 28

the higher the grid ratio the more the cleanup but ___ restrictive

Answer 28

more

Question 29

Grid conversion formula

Answer 29

mas1/mas2 = gcf1/gcf2

Question 30

this grid the Pb lines run in 1 direction only head to toe. Used most often. Can angle cephalic or caudal but not across the grid lines

Answer 30

Linear grids

Question 31

this grid the pb lines run at right angles to one a noter. cannot angle in any direction. and most restrictive.

Answer 31

Crossed of crossed hatch

Question 32

this grid the pb lines parallel to one another, have no set focusing sidtance

Answer 32

parallel or non focused

Question 33

this grid angled lead lines to use in a specific focusing distance

Answer 33

focused

Question 34

Where points converge in space from a focused grid

Answer 34

convergent point

Question 35

Grids that lay on top of IR usually taped to IR

Answer 35

Wafer Grid/ Stationary Grid

Question 36

Who invented the moving grid to blur grid lines?

Answer 36

Hollis Potter

Question 37

What are the 4 types of movement with a grid?

Answer 37

Reciprocating, Recipromatic, Oscillating, Single-stroke/ Sling Shot

Question 38

What is not a type of movement in a grid?

Answer 38

elliptical (tomo tube-travel pattern)

Question 39

Grids _____ contrast

Answer 39

increase (by absorbing scatter)

Question 40

Grids ____ pt dose

Answer 40

increase (because mAs is increased to maintain density)

Question 41

Grid to non grid

Answer 41

divide

Question 42

non grid to grid

Answer 42

multiply

Question 43

complete peripheral grid cut off? (no exposure on outer edges)

Answer 43

upside down focused grid cut-off

Question 44

when beam is angled across grid lines (most common, decrease in density)

Answer 44

off level grid cut off

Question 45

bucky not shoved in all the way or tube off center

Answer 45

off center grid cut off

Question 46

when SID is out of focusing range. acceptable density in center with decreased density on outside edges

Answer 46

off focus grid cut off

Question 47

when stationary grid is used during CR. can be solved with a higher ratio stationary grid or use a moving grid. also occurs as a faulty attempt at making a cross hatch grid

Answer 47

moire effect/ zebra pattern

Question 48

6'' air gap = 6:1 grid does what to contrast and density?

Answer 48

increased contrast, decreased density

Question 49

DR/CR more or less sensitive to scatter?

Answer 49

more