Test 3 Unit 3 Density

Question 1

films overall darkness. controlled by mAs but influenced by kVp and other components

Answer 1

density

Question 2

varying shades of gray on film. controlled by kVp

Answer 2

contrast

Question 3

affects density and detail. focal film distance, source to image distance. inversely proportional to film density.

Answer 3

FFD/SID - the longer the distance, the lighter the film.

Question 4

affects detail. object film distance

Answer 4

OFD

Question 5

film too light (too little density). not enough mAs

Answer 5

underexposed

Question 6

film too dark (too much density). too much mAs

Answer 6

overexposed

Question 7

appears black on the film. xrays pass right through

Answer 7

radiolucent

Question 8

appears white on film. xrays are absorbed and dont hit film

Answer 8

radiopaque

Question 9

can be easily removed from a patient before an xray is taken

Answer 9

artifact

Question 10

cannot be easily removed from patient

Answer 10

foreign body

Question 11

Why do you need to know if patient has foreign body?

Answer 11

you may have to increase or decrease amount of xrays needed

Question 12

quantity of electrons to be boiled off filament. There is a direct relationship between this and mAs.

Answer 12

mA

Question 13

tells the cathode the time the electrons have to boil off the filament. There is a direct relationship between this and mAs.

Answer 13

s

Question 14

the quantity of xrays produced. Responsible for density on a radiograph

Answer 14

mAs

Question 15

composition of mAs

Answer 15

99% heat, % xrays

Question 16

4 factors for xray production

Answer 16

1. source of electons 2. thermionic emission of xrays 3. electrons set in motion 4. electrons stopped abruptly at target

Question 17

What happens when electrons are set in motion?

Answer 17

Strong positive charge of anode attracts e-. E- accelerate from 0-1.5 billion meters/s.

Question 18

What is the distance from the cathode to the anode?

Answer 18

2cm

Question 19

What happens when electrons stop at target?

Answer 19

Sudden stop and collision with anode target converts e- energy to: xray energy 99%

Question 20

50% reciprocal rule

Answer 20

if film is too dark (dense), cut mAs in half. If film is too light, double mAs.

Question 21

30% Rule

Answer 21

a 30 % change in mAs is required to even see a visible change in darkness on a film. Doubling or halving the mAs will double or half the film density

Question 22

Secondary factors that affect film density

Answer 22

kVp, FFD, patient size and shape, pathology, film processing, grids/grid ratio, film-screen speed, compensation filtration

Question 23

used to maintain radiographic density when distance changes. When distance increases, triple mAs. When distance decreases, divide by 3.

Answer 23

Direct square law

Question 24

a compound that reduces exposed silver to black atomic silver. directly proportional to concentration and temperature and time. Any decrease in one of these will result in lighter film.

Answer 24

developer

Question 25

inside cassettes and contact with film. contain phosphor crystals. 4 layers

Answer 25

screen

Question 26

4 layers of screen

Answer 26

base, undercoating, phosphor layer, and protective layer

Question 27

cassette construction

Answer 27

cassette front (radiolucent carbon fiber), compression foam, screen, phosphor layer

Question 28

more light from the phosphors emitted, less xrays required. brighter screen. less xrays needed. less detail. patient exposure reduced

Answer 28

fast screen (400)

Question 29

less light from the phosphors emitted, requires more xrays. better detailed. increased patient exposure. Usually for extremities

Answer 29

slow screen (200)

Question 30

large patient size

Answer 30

hyperstenic

Question 31

average patient size

Answer 31

stenic

Question 32

thinner than average patient size

Answer 32

asthenic

Question 33

super thin patient size

Answer 33

hypostenic