Ch 8 X-ray Emission

Question 1

intensity of the beam is measured in _____ aka _____

Answer 1

mGya (mR) aka quantity or radiation exposure

Question 2

mGya (mR) is a measure of:

Answer 2

the number of ion pairs produced in air by a quantity of x-rays

Question 3

radiation exposure rate is expressed in ____ and can also be used to express ______

Answer 3

mGya/s, mGya/min, mGya/mAs and can also be used to express x-ray intensity

Question 4

*x-ray quantity is the ____

Answer 4

number of x-rays in the useful beam

Question 5

x-ray quantity is _____ to mAs

Answer 5

directly proportional

Question 6

the change in x-ray quantity is proportional to the _____

Answer 6

square of the ratio of the kVp

Question 7

if kVp were doubled the x-ray intensity would:

Answer 7

increase by a factor of 4

Question 8

*x-ray quantity is proportional to:

Answer 8

the kVp squared

Question 9

doubling the x-ray intensity by kVp alone requires:

Answer 9

an increase of 40% in kVp

Question 10

an increase of 15% in kVp will _____ the mAs and should be accompanied with _____

Answer 10

double the mAs, a reduction of one half the mAs

Question 11

by increasing kVp and reducing mAs so that IR exposure remains constant, the patient dose ______; the disadvantage when the film is the IR is _______

Answer 11

is reduced significantly; reduced image contrast

Question 12

x-ray intensity varies inversely with the _____

Answer 12

square of the distance from the x-ray tube

Question 13

*x-ray quantity is inversely proportional to the _____

Answer 13

square of the distance from the source

Question 14

*when SID is increased, ___ must be increased by ____ to maintain constant exposure to the IR

Answer 14

mAs must be increased by SID^2

Question 15

the purpose of filters is to:

Answer 15

reduce the number of low-energy x-rays

Question 16

*adding filtration to the useful beam reduces:

Answer 16

patient dose because fewer low-energy x-rays are found in the useful beam

Question 17

x-ray beam hardening increases:

Answer 17

the number of high energy x-rays in the beam by removing the lower energy non penetrating x-rays

Question 18

penetrability aka ____

Answer 18

quality

Question 19

*penetrability is the ability:

Answer 19

of an x-ray beam to pass through tissue

Question 20

______ and _____ do not affect radiation quality; they do affect radiation quantity

Answer 20

distance and mAs

Question 21

x-rays of any given energy are more penetrating in _______

Answer 21

material of low atomic number

Question 22

*attenuation is:

Answer 22

the reduction in the x-ray intensity that results from absorption and scattering

Question 23

quality of x-rays is measured by the ____

Answer 23

HVL

Question 24

HVL is a characteristic of the:

Answer 24

useful beam

Question 25

HVL ranges from:

Answer 25

3-5 mm Al or 3-6 cm soft tissue

Question 26

*the HVL of an x-ray beam is the:

Answer 26

thickness of absorbing material necessary to reduce the x-ray intensity to half its original value

Question 27

*HVL is the best method for:

Answer 27

specifying x-ray quality

Question 28

*x-ray beam quality can be identified by ___ or ____, but ____ is most appropriate

Answer 28

kVp or filtration, but HVL is the most appropriate

Question 29

*increasing kVp increases:

Answer 29

the quality of the beam

Question 30

an increase in mAs:

Answer 30

increases quantity alone

Question 31

an increase in kVp:

Answer 31

increases both quantity and quality

Question 32

an increase in distance:

Answer 32

reduces the quantity and does nothing to the quality

Question 33

an increase in filtration:

Answer 33

reduces the quantity and increases the quality

Question 34

*increasing filtration increases:

Answer 34

the quality of the beam

Question 35

filtration of diagnostic x-ray beams has 2 components:

Answer 35

inherent and added filtration

Question 36

inherent filtration:

is approximately ____ equivalent

Answer 36

the glass or metal enclosure of the x-ray tube filters the emitted beam

is approximately 0.5 mm Al equivalent

Question 37

added filtration:

Answer 37

a thin sheet of Al positioned b/w the protective x-ray tube housing and the x-ray beam collimator

Question 38

*added filtration results in:

Answer 38

increased HVL

Question 39

the addition of a filter to an x-ray beam:

Answer 39

attenuates x-rays of all energies emitted, but it attenuates a greater number of low-energy rays

Question 40

compensating filters:

are useful for:

Answer 40

compensate for differences in subject radiopacity (body parts that vary greatly in thickness or tissue composition)

are useful for maintaining image quality

Question 41

*SID changes will affect _____ not _____

Answer 41

quantity NOT quality

Question 42

*the higher the mm filter it is, the _____ the penetration of the beam (higher HVL)

Answer 42

greater

Question 43

*when operating on <50 keV you need ____ total filtration

Answer 43

.5 mm Al

Question 44

*when operating on 50-70 keV you need ___ total filtration

Answer 44

1.5 mm Al

Question 45

*when operating on 70+ keV you need _____ total filtration

Answer 45

2.5 mm Al

Question 46

*less filtration is necessary at ____ energy

Answer 46

less

Question 47

*the mirror of the collimator is _____ Al and a part of _____ filtration

Answer 47

1 mm Al and a part of added filtration

Question 48

*the tube proper is ____ Al and a part of ______ filtration

Answer 48

.5 mm Al and a part of inherent filtration

Question 49

*with filter wedges you want the _____ mm at the ____ part

Answer 49

thinner mm at the thicker part

Question 50

*total filtration = ______+______

Answer 50

added + inherent

Question 51

*photoelectric effect has the _____ B/W/Grays

Compton scatter has the ____ B/W/Grays

Answer 51

photoelectric good B/W/Grays

Compton bad B/W/Grays

Question 52

*the higher the Z the _____ the absorption

Answer 52

higher

Question 53

*the _____ the gray the more absorption

Answer 53

lighter gray

Question 54

*the _____ the mAs density the more absorption

Answer 54

greater

Question 55

*as energy increases ____ is more common than _____

Answer 55

Compton is more common than photoelectric