Jerry I Flashcards by hang c cao

The x-rays that penetrate through the housing of the x-ray tube are called_____ radiation.

Leakage

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Having fewer x-rays on the anode side of the image receptor in comparison with the cathode side is called _______

Heel effect

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_________ produces images of reduced intensity outside the edges of the collimated filed of view

Off focus

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That the effective focal spot size is smaller than the area where the x-rays are actually produced because of the beveled angle of the x-ray tube target is called _____

Line focus principle

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_________ is attributed to attenuation within the target of the x-ray tube.

Heel effect

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Federal regulations limit leakage raditation at a distance of 1 meter to an amount less than ______ mR/hr at higheest kVp and maximum continous mA

100

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If the mA used during measurement of the effective focal spot of an x-ray tube is increased, the measured dimension of the focal spot size _________

Is increased

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If the kVp used during measurement of the effective focal spot of an x-ray tube is increased, the measured dimension of the vocal spot zied _________

Decreases

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For the same effective focal spot size, the _____ as the anode angle is decreased from 12 to 8 degrees

Heat distribution improves

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X-ray radiation levels at the image receptor increase with an increase in all of the following parameters, EXCEPT _______(SID/kVp/mA/exposure duration(s)/anode angle)

SID

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the cutoff on the anode side of the image receptor is more severe when ______

SID is smaller

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One of the two key purposes of x-ray beam collimation is to________

Reduce the scattered radiation

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______ percent of the bombarding electrons’ energy is converted in x-ray production.

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The part of the x-ray tube responsible for the heat distribution in the anode is the _______.

rotor

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Secondary radiation consists of scattered x-rays plus _______

Leakage radiation

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The main x-ray tube factor that affects the spatial resolution in the image is the _____

Effective focal spot size

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The spatial resolution in the image is always better __________

On the anode side

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The factor that results in the largest increase in the x-ray output is to ______

Double the mAs

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For a constant filament size, all of the following cause more image blur, EXCEPT______(Small anode angle/lower kVp/higher mA/greater geometric magnification/longer exposure times)

Smaller anode angle

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To prevent anode cutoff at 100cm with the largest cassette (35 cm x 43 cm), the anode angle must be no less than _____ degrees

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Bremsstrahlung x-ray production accounts for _______ % of all the x-rays.

85-100

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The energy spectrum of bremsstrahlung x-rays is _______.

Polychromatic

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The shortest wavelength x-ray photons are dependent on ________

kVp

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The longest wavelength x-ray photons are dependent on _______

X-ray beam filtration

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The K-characteristic x-rays for a tungsten x-ray tube target have energies of about _____ keV

50-70

The K-characteristic x-rays for a rhodium x-ray tube target have energies of about ______ keV

20-23

the K-characteristic x-rays for a molybdenum x-ray tube target have an energy of about _____ keV

17-20

The L-characteristic x-rays for a tungsten x-ray tube target are usually_____

An insignificant (khong dang, kong quan trong) portion of the total x-ray production

A single bombarding electron that undergoes several bremsstrahlung interactions in the x-ray tube anode produces ________

Several low-energy x-rays

If the average energy of an x-ray spectrum is approximately 40 keV, the voltage across the x-ray tube must be around ______ kVp.

80-120

To be able to produce K-characteristic x-rays in a tungsten target x-ray tube, the x-ray tube voltage must be no lower than _____ kVp

69.5

The x-ray quantity increases when the ____ is larger in magnitube.

kVp and mAs

The quality (ability of x-rays to penetrate through the patient's body) improves when the _______ is larger in magnitube

kVp and Filtration

The contrast in radiographic images degrades when the _____ is larger in magnitube

kVp and Filtration

The relative amount of scattered x-rays increases when the ____ is larger in magnitube

kVp and Filtration

The quantity of the bremsstrahlung x-rays depends on _______

kVp, mAs, and Filtration

The quantity of the characteristic x-rays depends on all of the following, EXCEPT: .........................(kVp/SID/mAs/atomic #/mass #)

Mass number

If the x-ray tube voltage is increased from 60 to 120 kVp, the quantity is changed by _____ the previous value

4.0 times

If the mAs is doubled, the quantity of the x-ray beam is changed by ____ the previous value

2.0 times

quantity is usually measured in units of_____

QUALITY is usually measured in units of _____

mm of aluminum [nhom]

An increase in filtration with a corresponding increae in mAs in order to maintain radiographic film density constant results in ____ to the patient's skin entrance radiation dose

A decrease

The quality of the characteristic x-rays is affected by the ______

Atomic number [Z number]

Higher amounts of ______ increase both the quantity and QUALITY of an x-ray beam

kVp

The filament circuit uses_______

Step-down transformer

the line regulator uses ________

Autotransformer

The high-voltage (kVp) circuit requires _____ and _______

Step-up transformer and Rectifiers

a high-frequency generator requires ________

Inverter circuit

Changing AC current to DC current requires _________

Rectifiers

The voltage required to remove most of the space charge around the filament and collect more of the thermionic emitted electrons is called the _____ voltage

Saturation [voltage]

the x-ray generator (high-voltage section) that produces the most x-rays per mAs at a given kVp and distance is ______

Constant potential

The generator that uses six [6] diodes for the high-voltage rectification is _______

3-phase, 6-pulse

the x-ray generator tha thas the least penetrating x-rays and results in the highest radiation does to the patient for the same kVp and same film density is the _____

Single phase

The x-ray generator with the smallest transformer size is the ______

High-frequency

The x-ray generator that produces the smallest amount of x-rays for a give setting of kVp and mAs is_______

Signle phase

The x-ray generator that produces 180 pulses per 500 millisecond exposure is _______

3-phase, 6-pulse

the x-ray generator that has 100% ripple in the kVp waveform is the _______

Single phase

The space charge effect dissipates at an x-ray tube potential of about ______kVp

The x-ray timer circuit that uses radiation measurements to terminated the exposure is called a(n) _______ timer.

Automatic exposure control (AEC)

The most common x-ray exposure timer, which can adjust to exposure durations from several seconds to 1 millisecond, is the ______ timer

R-C

Timer circuits terminate x-ray exposures by interrupting the _____

Primary current of the step-up transformer

The device tha stores electrical charge and is used in timer circuits is called a _____

Capacitor

The ______ allows electrons to flow in only one direction

Diode

The equation for Ohm's law is _______

R = V/I [Resistance = Voltage/Current]

the device that does NOT function with DC power is a _______

Transformer

A transformer can regulate all the following electrical paramters, EXCEPT_____ (Voltage/current/phase/power/inductance)

Power

Ripple in the x-ray tube voltage is undesirable [thi khong tot] because it reduces _____

X-ray production

the x-ray tube current is monitored on the ______

Secondary side of the step-up transformer

Typical values for the filament current are around ______mA, and typical values for the tube current are _____ ma.

5000, 500

At diagnostic x-ray energies, the _____ interaction between x-rays and matter [car vat] has the same mass attenuation coefficient in all elements of the atomic table )except for hydrogen).

Compton scatter

The ----------interaction between x-rays and matter depends strongly on the atomic number (Z) of the attenuation material

Photoelectric effect

In the _____ interraction between x-rays and matter, the photon disappears, and an electron and a positron are creasted

Pair production

The ______ interaction between x-rays and matter requires photon energies greater than 5 to 10 MeV

Photonuclear disintegration

the probability of ______ interaction between x-rays and matter decreases in inverse propartion to the photon energy cubed

Photoelectric effect

the _____ interaction between x-rays and matter requires photon energies greater than 1.02 MeV before it can occur

Pair production

For incident photons with high energies, the _______ interaction between x-rays and matter results in photons that are scattered primarily in the forward direction

Compton scatter

The probiability of _____ interaction between x-rays and matter depends primarily on the electron density of the attenuation material

Compton scatter

The ____ and ______ interactions do NOT occur at diagnostic x-ray energies

Pair production and Photonuclear disintegration

The probability[co hoi] of ______ interaction between x-rays and matter depends on the physical density of the attenuation material

all of the above: photoelectric effect, compton scatter, coherent scatter, pair production, and photonuclear disintegration

The probability of _____ interaction between x-rays and matter depends on the thickness of the attenuation material

all of the above: photoelectric effect, compton scatter, coherent scatter, pair production, and photonuclear disintegration

The primary shielding material for diagnostic x-ray is ______

Lead [chat thiet]