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RAD 1 > Pg 33- > Flashcards

Pg 33- Flashcards

1
Q

What is bremsstrahlung radiation

A

Interaction of incoming electron with target nucleus, electron passes close to nucleus and changes direction which causes loss of energy which is converted into xray

Makes up 85% of xray beam

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2
Q

What is characteristic radiation

A

A incoming electron interacting with a target electron, the electron collides with the K shell target electron knocking it outta orbit. To replace the K shell electron the outer shell electron moves down.

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3
Q

What are the two types of filtration with tube complex

A

Inherent and added

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4
Q

Filtration attenuates (reduces)

A

Beam intensity

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5
Q

Soft rays _______ the skin entrance and organ dose to patient

A

Increase, hence why they are filtered out. Normally measured in aluminum (AI) thickness

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6
Q

What is half value layer (HVL)

A

The amount of material needed to reduce beam intensity by 1/2. its used for filtration recommendations and regulations.

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7
Q

What is inherent filtration

A

From the oil and glass window, is equivalent to 1/2 mm of AI thickness. Manufacturers add 1-2 mm of AI to the housing port

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8
Q

How much filtration is required for 70-100 kV

A

2.5 mm

HVL for up to 125 kV is 3mm of AI most machines are this.

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9
Q

Most machines are rated a _____ kV

A

125 but usually dont use above 100 for spine, sometimes for chest

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10
Q

What limits the beam to the desired port or film size

A

Collimation,

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11
Q

Collimation helps reduce

A

Secondary exposure to patient and operator, also improves film quality by reducing the secondary rays

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12
Q

Where is a collimator fitted

A

On front of the tube housing

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13
Q

Collimators have ____ shutters and can be

A

4, adjusted to desired size, shutters are made of lead

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14
Q

2 adjustment knobs on collimator that both work

A

Independently

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15
Q

When smaller than film size there will be

A

Collimation cut off

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16
Q

If collimation is too tight the film will be

A

Over colliimated. To large then its under collimator

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17
Q

Cut off will be ______ or ______ due to primary beam absorption

A

White, light

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18
Q

Often the area of cut off is gray or dark due to secondary exposure from the patient but not

A

As dense as the primary exposure . Also can happen from off focus radiation (rays exiting anode other than the target)

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19
Q

Cut off occurs when

A

Collimating to part size instead of film size

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20
Q

Cut off will be equal if CR and film are

A

Centered

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21
Q

The center of a beam after collimation through the glass window is shown by cross hair formed by

A

Horizontal and vertical lines, postition the tube vertically and patient horizontally

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22
Q

Collimator accuracy is require to be within ____ of the distance between focal spot and film

A

2%

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23
Q

What are the 3 basic types of collimation

A

Manual- all adjustments made by operator
Semiautomatic
Automatic- semi and full automatic ar POSITIVE BEAM LIMITATION devices (PBL)

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24
Q

PG. 39 about cross hairs on patient look at it super easy

A

Yep!!!

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25
Q

What is selective/ compensating filtration

A

Improves film quality, compensates for patients varied thickness

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26
Q

Selective filtration can

A

Lessen intensity to the thinner parts of the body, should be placed between the tube and patient to reduce exposure

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27
Q

What are portal filters

A

Are placed on the front of the beam limiting device, usually made of aluminum or copper.

28
Q

Selective filters are ________ with spinal radiography

A

Necessary, used during full spine films and most A-P and lateral thoracic films

29
Q

Selective filters can be used on feet to filter

A

Toes

30
Q

A line can be seen between filtered and unfiltered part unless

A

The filter was tapered

31
Q

Wedge filters taper

A

Thus no line of demarcation between the filtered and unfiltered area called wedge filter system

32
Q

What is the most common filter used in chiropractic

A

Nolan filter system

33
Q

What is a underpart filter

A

Refers to reducing the beam intensity after it passes through the patient thus adding unneeded exposure, mostly in the form of SPLIT SCREENS, often used for full spine films

34
Q

Plating and arcing of the tube damage it which

A

Wears down the ball bearings causing slower rotation and anode surface melting

35
Q

To help prevent tube failure

A

Limit the time you hold the rotor button to prevent increased thermionic emission. Excessive exposures may cause anode pitting of tube if not cooled sufficiently before another exposure

36
Q

What are heat units (HU)

A

Calculates by mA x time x kV. Tube rating and tube cooling charts included

37
Q

What is recommended if tube hasn’t been used for a number of hours before a large exposure

A

Warm up, this prevents thermal shock to the anode which can cause your anode to crack or more likely the anode stem to crack and break off

38
Q

If you need to increase the mAs do it either with the

A

MA STATION OR TIME

39
Q

A lower mA setting will ______ tube stress

A

Lessen

40
Q

Generators normally require

A

220 volts and 100 amps, some new units run on 100 volts called sorted energy units which operate with a battery.

HOWEVER 220 is more commonly used

41
Q

What do transformers do

A

Change incoming current

42
Q

Whats a high voltage transformer

A

Converts volts to kilovolts 1000 volts= 1 kV and kV are needed for xray

43
Q

_________ kV are most commonly used for offices

A

40-125

44
Q

A high voltage transformer is also called a

A

Step up transformer or high voltage circuit

45
Q

A filament circuit converts arms to

A

Milliamps (mA) 1/1000th of an amp is 1 milliamp

50-300 mA is usually used but can be higher (often 600)

46
Q

The filament circuit is also called

A

Filament transformer or low voltage circuit or step down transformer

47
Q

Rectifiers change current from

A

AC to DC

48
Q

Alternating current (AC) electrons move

A

Forward and backward, this would send electrons to the cathode and destroy it

49
Q

Direct current (DC) is needed for the tube bc

A

It travels in one direction from cathode to anode

50
Q

What is rectification

A

Changes the AC to DC and is done by the recitifiers. They are diodes. Eliminates the lower (-) pulse of the cycle protecting the filaments. The result is HALF WAVE RECTIFICATION

51
Q

What is full wave rectification

A

Changes the - to a + allowing 2 + pulses, more efficient than 1/2 wave rectification

52
Q

What is kilovolt peak (kVp)

A

The desired kV

53
Q

The kV builds up from 0 to the peak and then

A

Descends back to 0

54
Q

All of the kV below the peak make up some of the exposure which this variable is called

A

Ripple, the less ripple the better

55
Q

Single phase generators have

A

1 line source and has maximum ripple

56
Q

A 3 phase generator has three separate intertwined incoming lines, which allows

A

More peaks and less dips. Results= less ripple

Maintains kV, its more efficient but not practical due to to expense

57
Q

High frequency generator have

A

Virtually no ripple allowing more accurate and predictable output. Even less ripple than 3 phase

58
Q

Benefits of high frequency generators

A

Produces greater photon energy, has fewer soft rays, gives patient less exposure, is affordable

59
Q

The longer the time, the more electrons bombard the anode which

A

Increases the number of X-rays

60
Q

How long is exposure time

A

1/120th of a second to a couple seconds.shortest time is preferred to reduced the chance of patient motion

61
Q

What are the types of timers

A

Synchronous, electronic, mAs, automatic exposure control

62
Q

Which timers are most accurate and versatile

A

Electronic, wider in use

63
Q

MAs timer combine mA and seconds in

A

1 control (popular), they are calculated using the lowest time and safest mA

64
Q

Automatic exposure control (AEC) has

A

Photocells in front of a film

65
Q

The 4 primary factors for controlling X-ray exposure are

A

Kilovoltage peak (kVp)
Milliamperage (mA)
Length of time of exposure
Distance of the tube from the receptor

66
Q

Photons striking the film is inversely proportional to the square of the distance

A

Inverse square law

RAD 1 (4 decks)

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