chapter 10 xray physics

Question 1

Image quality defined as?

Answer 1

is the fidelity of anatomical structures by the image

Question 2

the most important factors affecting quality of the image?

Answer 2

resolution

noise and artifacts

Question 3

what are the 2 different forms of resolution

Answer 3

spatial and contrast

Question 4

noise is defined as in an image?

Answer 4

random variation in optic denstiy of image

Question 5

what is optic density?

Answer 5

how much light can be transmitted through

Question 6

which of the 5 basic interaction of matter are considered important when it comes to noise?

Answer 6

compton because it deals with scatter e-

Question 7

what is film grain and how does it contribute the image?

Answer 7

it is finite small silver crystals that make up the image itself

Question 8

how does film grain affect the noise?

Answer 8

larger the film grain the more noise there is

Question 9

what are structure mottles?

Answer 9

they are large phosphor crystals of the intensifying screen

Question 10

how does structure mottles contribute the noise?

Answer 10

the larger the mottle structre the more noise there is

Question 11

how does speed affect the noise and resolution?

Answer 11

as speed increases the higher the noise is and the lower the resolution is

Question 12

how does higher speed affect the pt. dose and heat production?

Answer 12

as the speed increases the pt. dose decreases and the heat damage to the anode decreases

Question 13

slower speed has what affect on the image?

Answer 13

the resolution will increase but the pt. dose will increase and the heat damage to the anode

Question 14

the characteristic curve is used for _____ systems?

Answer 14

analog

Question 15

characteristic curve is for analog systems and it shows a response curve for xray films that demonstrated what characteristics?

Answer 15

density, contrast, speed, latitude

Question 16

When a xray machine uses film what characteristics of processing must you take into consideration?

Answer 16

time and temperature

Question 17

characteristic curve shows a relationship between what?

Answer 17

optical density and the radiation exposure.

Question 18

how would optical desntiy appear on the film?

Answer 18

as different shade of grey

Question 19

what happens to the optical density as the radiation exposure increases?

Answer 19

it becomes more black so it will increase

Question 20

what is another name for the characteristic curve?

Answer 20

hurter and driffield or H & D curve

Question 21

contrast of the radiographic image refers to the?

Answer 21

difference between the gray shades that comprise the image?

Question 22

the straighter the line is of the H & D curve shows what?

Answer 22

represents that any change in the exposure will make a greater change in film

Question 23

the straighter the line represent the film has what?

greater contrast OR Less contrast?

Answer 23

greater contrast in response to the exposure

Question 24

when looking at a characteristic curve you can notice which one is faster by noticing what about the exposure?

Answer 24

how much radiation exposure it takes

Question 25

the human eye can perceive optical densities in between what range?

Answer 25

0.25 (clear) and 2.5 (black)

Question 26

the xray film base is of what material?

Answer 26

polyester

Question 27

what is the OD of the xray film base?

Answer 27

0.1

Question 28

what is added to the xray film base to reduce glare in the view box?

Answer 28

blue dye

Question 29

how would you describe fog when it comes too OD?

Answer 29

any additional OD to the on a processed xray film that does not have a purpose will result in fog

Question 30

why is base and fog measured?

Answer 30

for quality control

Question 31

what is a desnitometer?

Answer 31

measure the OD of materials such as the film

Question 32

Base + fog should not exceed? | and should not be lower than?

Answer 32

0. 3 | 0. 25

Question 33

the latitude of the H & D curve demonstrates what?

Answer 33

the amount of exposure

Question 34

what does the magnification factor show a relationship between?

Answer 34

image size and object size

Question 35

focal film distance is also known as?

Answer 35

source image distance

Question 36

SOD is known as

Answer 36

source object distance

Question 37

OID is known as

Answer 37

object image distance

Question 38

what do measure by dividing SID by SOD

Answer 38

the magnification

Question 39

how does a smaller object distance affect the shadow?

Answer 39

it will get smaller

Question 40

is you increase the OID what happens to the magnification?

Answer 40

it gets bigger

Question 41

if you decrease the SOD or the OID what happens to the shadow?

Answer 41

it will get bigger

Question 42

how would a longer SOD affect the magnification?

Answer 42

reduces magnification

Question 43

distortion is defined as?

Answer 43

uneven magnification

Question 44

what may contribute to distortion

Answer 44

size shape position/orientation

Question 45

how does the shape of the object affect the shadow?

Answer 45

directly

Question 46

how does the shape of an object affect the grey shade?

Answer 46

does not change

Question 47

when considering object position what is important?

Answer 47

object symmetry with the image source

Question 48

as the object thickness what happens to the edge sharpness?

Answer 48

there will be 1/2 shadow area

Question 49

why is an objects orientation in space important?

Answer 49

a distorted image that apears foreshortened will be produced the more lateral to the central axis it lies

Question 50

due to distortion in the apparent length due to the orientation of space is the apparent length a good indicator to actual size?

Answer 50

no

Question 51

how does kVp effect the contrast changes?

Answer 51

higher kVp produces lower contrast with longer scale of grey shades and lower kVp produces higher contrast image with shorter scale pf grey shades

Question 52

kVP is the controlling factor of what?

Answer 52

contrast

Question 53

the mAs is the primary controlling factor of what?

Answer 53

film exposure

Question 54

why does short exposure times yield better image quality?

Answer 54

reduced pt. motion,