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XR > image production 4.2 102720 > Flashcards

image production 4.2 102720 Flashcards

1
Q

What regulates the duration of XR production

A

Timer

Most equipment uses electronic timer

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2
Q

What is located in the XR circuit between the high voltage transformer and the XR tube

A

Rectifier

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3
Q

Which of the following meausres tube current

A

mA meter

Current is flow of e measured in mA

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4
Q

What device spins at 10,000-12,000 rpm

A

Anode

High speed anodes spin at 10,000-12,000 rotations per minute.

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5
Q

What device uses maximum heat storage ability of the tube to deliver mAs

A

Falling Load Generator

FLG allows extremely short exposure times

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6
Q

What is the source of bremsstrahlung and characteristics rays

A

XRs produced by 2 different interactions

that occur between incident electrons fr cathode and tungsten atoms of the anode

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7
Q

What device increases voltage approximately 500 times

A

Step-up transformer

This where voltage is boosted to KV levels

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8
Q

What is the most commonly used AEC

A

Ionization chamber
This is located between patient and IR.
Phototimer are seldom used

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9
Q

What device always delivers the shortest exposure time possible

A

Falling Load Generator

Coupled with a timer exposure accurate to .001s, 1/1000, 1 ms

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10
Q

What device is turned by a rotor

A

anode

Pressing rotor button activates motor that turns anode.

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11
Q

Which of the following is located between the pt and the IR

A

Ionization chamber
Wafer thin chamber containing gas that is ionized by XRs passing thru.
At predetermined level of ionization exposure is terminated.

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12
Q

The filament is kept warm by

A

A standby current fr the time the XR machine is turned on.

The machine keeps filament warm between exposures.

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13
Q

Activating the rotor

A

reduces tube life

Each time rotor is activated thermonic emission begins to occur at filament. The heating of filament causes tungsten.

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14
Q

When making an exposer the tech should

A

activate the rotor and exposure switch in one continuous motion
bc it reduces XR tube life

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15
Q

The process of thermonic emission causes

A

Electrons to boil off the filament

This causes space charge/ or electron cloud to form around filament

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16
Q

The force with which the electron stream passes from cathode to anode is a result of ____________ passing thru the XR tube

A

kilovoltage

Voltage is the force behind the movement of electrons in a circuit

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17
Q

Heat is produced in XR tube as

A

electrons interact with the target material

Due primarly to bremsstrahlung at the anode

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18
Q

Most of the energy conversion in the XR tube produces

A

Heat

99% of incident electrons of kinetic enegy is converted to heat energy. 1% converted to XR energy.

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19
Q

XRs are produced as incident electrons are slowed going past the nuclei of target atoms by a process called

A

Bremsstrahlung
As incident electrons fly past the atomic nuclei and they are slowed causing production of heat and XRs are also produced by the characteristic interaction.

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20
Q

XRs are produced as incident electrons collide with inner shell electrons in target atoms by a process called

A

characteristic

As incident electrons dislodge, K-shell electrons in target material outer shell electrons fall inward to fill the holes

21
Q

Properties of XRs

A
  1. affect film emulsion
  2. scatter and produce secondary radiation
  3. invisible to the human eye
  4. travel in bundles of energy called photons/quanta
  5. can ionize matter and gas
  6. cause phosphors to fluoresce
22
Q

The XR beam is

A

heterogeneous or polyenergetic- consisting of many different energies (wavelengths)
homogeneous- all ray possess the same energy

23
Q

The XR emission spectrum consists of

A

discrete spectrum (characteristic) and continuous spectrum (brem)

24
Q

The primary purpose of filteration is

A

radiation protection
Hardening the beam for imaging
Longwavelength = soft rays

25
Q

The material needed to reduce the intensity of the beam by 1/10 is called

A

Tenth-value layer

Beam quality is commonly discussed half-value layer

26
Q

When a quality control test is performed to ensure that the PENETRATING ABILITY OF THE XR BEAM is accurate, the result must be within what amount of the control panel setting

A

50%

27
Q

The primary type of grid used

A

focused

28
Q

The portion of the II tube that converts electron energy to visible light is

A

output phosphor

29
Q

The portion of the II tube that converts visible light to electrons

A

photocathode

30
Q

The input phosphor of the II tube converts

A

XR energy to visible light

XRs exiting pt strike input phospher as it glows with visible light

31
Q

Total brightness gain achieved using an image intensifier equals

A

Flux gain times minification gain

32
Q

PROGRAMS THAT DEAL with the safe and reliable operation of equipment

A

Quality control

33
Q

PROGRAMS THAT ADDRESS all aspects of the delivery of radiology services are called

A

Quality assurance

34
Q

An image intenifiers conversion factor is expressed as the ratio of

A

the luminance of the output phosphor to the exposure rate at the input phosphor

35
Q

The collimator must be accurate to the level of

A

=/- 2% of the SID

QUALITY CONTROL STANDARD

36
Q

KVP must be accurate to within

A

10% of the control panel settings

or 4-6 KVP

37
Q

Exposure linearity (mA) must be accurate to within

A

10%

38
Q

Exposure reproducibility (AEC) must be accurate to within

A

5%

39
Q

The test that measures the accuracy of adjacent mA station is

A

Exposure linearity (5%)

40
Q

The test that measures the accuracy of successive exposures (AEC) is

A

Exposure reproducibility (5%)

41
Q

The accuracy of the timer must be within

A

5% of the time chosen for exposures over 10ms

42
Q

Fluoroscopy exposure rate may not exceed

A

100mGyair per minute

It is measured in-air at table top

43
Q

The feature that automatically adjusts KVP and mA during fluoroscopy is called

A

ABC

Automatic Brightness Control

44
Q

Resolution of the television system may be measured using the following tool

A

Resolution per test pattern

45
Q

An IIs conversion factor is expressed as the ratio of

A

The luminance of the output phosphor to the exposure rate at the input phosphor

46
Q

The number of mAs used for analog fluoroscopy is

A

3 to 5

This is asking mA actually used and not the setting of the mA at control panel

47
Q

Marks on the focal track of the anode resulting from bombardment of electrons are called

A

pitting

48
Q

Effective quality control and quality assurance programs are required for accreditation by

A

The Joint Commission (TJC)

Rep of TJC reguarly visit healthcare facilities

XR (10 decks)

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