Chapter 3 : Radiation Characteristics Flashcards

1
Q

The term “quality” in dental imaging

A

the energy or penetrating ability of the xray beam

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2
Q

Voltage

A

measurement of force of the potential difference between two electrical charges

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3
Q

When voltage is increased the speed of the electrons is ______

A

increased

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4
Q

when the electrons strike the target with greater force and energy, what resutls?

A

penetrating xray beam with a short wavelength

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5
Q

Measurement of Voltage

A

Volts (v) or kilovolts (kV)

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6
Q

1 kV equals

A

1000 volts

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7
Q

Kilovoltage

A

Maximum voltage of an alternating current

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8
Q

the use of higher kV produces what?

A

more penetrating xrays

with greater energy

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9
Q

current intra oral settings in kV range

A

60-70kV

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10
Q

regulates the speed and energy of the electrons and determines penetrating ability of xray

A

quality

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11
Q

Density

A

overall darnkess or blackness of an image

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12
Q

if the kV is decreased the resultant image exhibits a _____ density and appears _____

A

decreased

lighter

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13
Q

increased kV = _____ density (darker)

A

increased

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14
Q

contrast

A

differences of dark and light areas in an image

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15
Q

an image with “high contrast” has many ____ areas _____ areas and few shades of ______

A

black
white
grey

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16
Q

an image with “low contrast” has many shades of ______ instead of areas that are predominently ______ and _____

A

grey
black
white

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17
Q

exposure time

A

interval of time during which xrays are produced

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18
Q

impulse

A

measurement that refers to the fact that xrays are created in a series of bursts or pulses rather than a continous stream

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19
Q

one impluse occurs every _/__ of a second

A

1/60

20
Q

kilovoltage and _______ are inversely related

A

exposure time

21
Q

Quantity of the xray beam

A

number of xrays produced in the dental xray unit

22
Q

amperage

A

measurement of the amount of electrons passing through the cathode filament

23
Q

ampere (A)

A

measures number of electrons, or current flowing in the cathode filament.

24
Q

One milliamperage (mA)=

A

1/1000 of an ampere

25
Q

What does the milliamperage regulate?

A

temperature of the cathode filament

26
Q

an increase in the number of electrons that strike the anode ,_______ the number of xrays emitted from the tube

A

increases

27
Q

how does milliamperage effect the density of an image

A

when mA is increased, the overall density also increases which results in a darker image.

28
Q

increased mA = ____ density & ___ image

A

higher

darker

29
Q

KLMN

A

Kv=quaLity

Ma=quaNtity

30
Q

higher kV= ____ exposure time

A

decreased

31
Q

lower kV = _____ exposure time

A

increased

32
Q

increased mA=______ exposure time

A

decreased

33
Q

decreased mA= ____ exposure time

A

increased

34
Q

intensity

A

product of the quantity AND quality per unit of area

per unit of time exposure

35
Q

regulates the penetrating power of the xray beam by controlling the speed of the electrons while travelling between the cathode and anode

A

kilovoltage

36
Q

controls the penetrating power of the xray beam by controlling the number of electrons PRODUCED in the xray tube and the number of xrays produced.

A

milliamperage

37
Q

as with mA this also affects the number of xrays produced

A

exposure time

38
Q

target surface distance

A

distance from the source (tungsten target in anode) of radiation to the patients SKIN

39
Q

target object distance

A

distance from the source (tungsten target in anode) of radiation to the tooth

40
Q

target-receptor distance

A

distance from the source (tungsten target in anode) of radiation to the receptor

41
Q

as x rays travel away from their source of origin, the intensity of the beam _____

A

lessens

42
Q

The inverse square law

A

the intensity of radiation is proportional to the square of the distance from the source of radiation

43
Q

according to the inverse square law, when the target receptor is doubled, the resultant beam is __/__ as intense

and when the target receptor distance is REDUCED by HALF, the resultant beam is ___ times as intense

A

1/4

four

44
Q

The thickness of material (aluminum) that, when placed in the path of the x-ray beam, reduces the exposure rate by one-half.

A

half value layer (HVL)

45
Q

If an xray beam as an HVL of 4 mm, a thickness of __ mm would be necessary to decrease its intensity by half

A

4