arrt review: safety Flashcards by Sydney Luella

a ___ degree angle to the beam’s ________ and several feet away from the patient generally minimizes exposure

90, entry point

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generally, a ______ kVp will result in a lower entrance skin exposure than a ______ kVp technique

higher, lower

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what types of generators will yield lower entrance skin exposure?

three phase/high frequency will be lower than single

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two purposes of primary beam restriction

restricts beam to area of interest
reduces amount of tissue exposed to the radiation beam

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types of beam restriction

collimators
positive beam limitation (PBL)
cylinders/cones
aperture diaphragm

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formula for calculating field size

field size/aperature opening = SID/source to aperature opening distance

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filtration that increases the effective energy and quality of the x-ray beam

hardening

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maximum thickness requirements in useful beam
below 50 kVp

0.5 mm aluminum

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maximum thickness requirements in useful beam
50-70 kVp

1.5 mm aluminum

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maximum thickness requirements in useful beam
above 70 kVp

2.5 mm aluminum

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total filtration = ______________ + ________________

inherent + added

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what is included in inherent filtration?

the glass envelope, insulating oil, collimation mirrors

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what is included in added filtration

aluminum (or other materials)

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digital imaging eliminates retakes due to overexposure of up to __% and underexposure up to ___%

500%, 80%

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air gap technique requires a __________ combined with _________

a long SID, an increased OID

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air gap techniques do not ____________ but rather _____________

reduce scatter production, reduce its effect

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why does an air gap technique work?

high percentage of scatter diverges away from the IR

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1 inch = ___ centimeters

2.54 centimeters

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minimum source to skin distance for fluoro units = ____ inches for fixed units, ___ inches for mobile

15 inches for fixed, 12 inches for mobile

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what does DAP stand for?

dose area product

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what is DAP used for?

used to measure total dose to patient site in order to reduce patient radiation dose

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what is DAP expressed in?

mGy-cm2

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minimum cord length on mobile x-ray unit

6 feet

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DAP is the ________ striking the surface of the patient

total air kerma

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medical imaging's principle of radiation protection is based on the ____________________ dose response relationship

non-threshold, linear

1 mGy = __ mRm

100 mRm

natural sources of radiation; which is the largest?

radon, cosmic, terrestrial radon is the largest

natural sources of radiation amount to __% of annual exposure to ionizing radiation

82%

how much average yearly dose from all sources? How is this sub-divided?*

5.5 mSv 3.1 mSv medical 2.3 mSv background 0.1 mSv human-made radiation

artificial (man-made) radiation sources; which is the largest

medical imaging, nuclear fallout, consumer products medical imaging is largest

between time, distance, and shielding, which is the most effect mother of personnel protection

distance

minimum lead equivalent lead aprons

0.5 mm Pb

minimum lead equivalent lead aprons for fluoro/mobile

0.25 mm Pb

minimum lead equivalent gloves

0.25 mm Pb

minimum lead equivalent thyroid shield

0.5 mm Pb

minimum lead equivalent glasses

0.35 mm Pb

minimum lead equivalent bucky slot cover

0.25 mm Pb

minimum lead equivalent spot film device protective curtain

0.25 mm Pb

minimum lead equivalent clear lead-plastic overhead protective barrier

0.5 mm Pb

primary protective barriers are those surfaces that ________________, located __________ to the primary beam

can be struck by the primary beam, perpendicular

primary protective barriers require ______ of (aluminum/lead) equivalent

1/16 inch, lead

if the primary barrier is a wall, the lead requirement must extend ____________ up from the floor

7 feet (2.3 meters)

occupancy factor controlled area: exposure rate must be no greater than ______

100 mR/week

occupancy factor uncontrolled area: exposure rate must be no greater than ______

10 mR/week or .1 mGy/week

secondary protective barriers are those surfaces that ________________

are struck with stray radiation (leakage and scatter)

secondary barriers that are located parallel to the primary beam require _____ of (aluminum/lead) equivalent

1/32 inch, lead

_______ of the secondary barrier must overlap the primary barrier where the two meet

1/2 inch

maximum exposure rate of table top of a fluoro unit is ______, or cannot exceed _____ for each mA of operation at 80 kVp

10 R/minute, 2.1 R/minute

fluoro function designed to maintain a predetermined level of light intensity exiting the image intensification tube

automatic brightness control (ABC)

1 rem = ___ mSv

10 mSv

decreasing the pulsed fluoroscopy frame rate can (increase/decrease) patient's radiation dose**

decrease

in direct action of radiation, the x-ray hits which part of the cell?

DNA molecule

lethal effects to the zygote/embryo/fetus are most likely in which stage of pregnancy?

germinal

what type of chromosome break is most easy to repair?

small base pair lesion

what type of chromosome break is most difficult to repair?

double strand break

the relationship between the DAP and field size is _______

directly proportional

coherent interactions occur with a beam carrying ____________ of energy

less than 10 keV

how soon can short term effects of radiation exposure be seen?

within minutes

does coherent scattering result in ionization?

which of the following is most effective in reducing patient dose during a radiographic procedure? use lead apron use a high kVp collimate to area of interest increase distance between tube and patient

collimate to area of interest

inherent filtration (increases/decreases) the need for additional filtration. why is this?

decreases; x-ray divergence/reduction in beam intensity

wavelength is the _____________ between _________________

distance, two successive peaks of an electromagnetic photon

frequency is the ________________________ and is measured in the unit ___________

rate of rise and fall (oscillation) of the EM photon, Hertz (Hz)

How does increasing energy affect frequency & wavelength?

increase frequency, decrease wavelength

does the velocity of an x-ray photon ever change?

no, it stays the same (frequency and wavelength can change, but the speed is the same)

What interaction is responsible for patient dose?

photoelectric

What is responsible for tech dose?

Compton

total absorption of the x-ray photon

photoelectric interaction

partial absorption of the x-ray phton

Compton interaction

memory trick for remembering measurement information

The A’s have Grays (Gy) The E’s Have V’s ( Sievert Sv) If there is a Q it multiplies 2 (Equivalent dose)

thermionic emission requires _____ amps of current

4 to 6 amps

x-ray production is ___% heat and ___% x-rays

99% heat, 1% x-rays

__% of x-rays are produced with Bremsstrahlung interactions and (~) remaining are with ___________

90%, characteristic

accumulated dose record purpose provides an indication of working habits for works that can potentially be exposed to ___% of the annual total effective dose limit

how long must accumulated dose records by kept?

as long as the worker is employed in medical imaging

what type of dosimeter is least sensitive to radiation?

film badge

radiation monitoring devices should be worn if the radiation worker is at risk of receiving __% of the annual ____________________ limit of ___ rem

10%, annual effective absorbed dose equivalent, 5.0 rem

NCRP recommendation exposure limits annual whole body exposure in mSv in rem

50 mSv 5.0 rem

NCRP recommendation exposure limits lens of the eye in mSv in rem

150 mSv 15 rem

NCRP recommendation exposure limits all other areas (red bone marrow, breast, lung, extremities, etc.) in mSv in rem

500 mSv 50 rem

NCRP recommendation exposure limits cumulative effective limit

1 rem x age in years (10 mSv x age in years)

annual effective dose equivalent limit for public = ____ annual effective dose equivalent limit for occupational = ____

public = 0.5 rem occupational = 5 rem

annual effective dose equivalent limit for public = ____ in mSv in rem

5 mSv 0.5 rem

embryo/fetus exposure level limit for entire pregnancy in mSv in rem

5 mSv (0.5 rem) for entire pregnancy

embryo/fetus exposure level limit per month** in mSv in rem

0.5 mSv, 0.05 rem

what does DEL stand for in radiation safety?

dose equivalent limit

what is DEL a newer version of?

maximum permissible dose

what is dose equivalent limit/maximum permissible dose?

the maximum dose of radiation that in light of present knowledge would be be expected to yield any significant radiation effects

radiation limits fetus total = _____, Fetus monthly = _______ (pregnancy is 10 months)

fetus total = 5 mSv, fetus monthly = 0.5 mSv

Student radiographer dose = _____

1 mSv

arrt review: safety Flashcards

(90 cards)