Safety Flashcards
required amps for thermionic emission
4-6 amps of current
required voltage for thermionic emission
8-12 volts
what is focusing cup made of
Molybdenum or nickel
what percentage of electrons becomes heat / x-rays during exposure
99% heat, 1% x-rays
where does the current come from to produce thermionic emission
step down transformer
what charge does the anode carry
positive
atomic number of tungsten
74
what charge does the cathode carry
negative
material that makes up filament wire
thoriated tungsten
K shell election binding energy
69.53 kev
L shell electron binding energy
12 kev
M shell electron binding energy
3 kev
maximum number of electrons in shell formula
2n^2 where n is the shell number
maximum number of electrons in valence shell
8
90% of all x-ray production is from which interaction
Bremsstrahlung
the average energy of the central ray is about ___% of the peak energy (kVp)
30%
interactions that occur at the target / tube
Brehmsstralung, characteristic, heat
interactions that occur at the tissue
photoelectric absorption, compton scatter, coherent
which x-rays and interaction are considered diagnostically useful?
K-shell characteristic x-rays
at 85 kVp, __% of the beam is characteristic
15%
N shell electron binding energy
1 kev
forms of radiation that travel as particulate radiation
beta and alpha radiation
speed of light
3 x 10^8 meters/sec
what is the difference between x-ray and gamma rays?
source of origin
what is the relationship between wavelength and frequency?
inversely proportional
what is the relationship between wavelength and beam energy?
inversely proportional
what is the velocity of all electromagnetic radiation?
speed of light
what measures filtration
half value layer
which factors effect the half value layer
kVp and filtration
image forming radiation is also known as
remnant radiation / exit radiation
the absorption of the x-ray beam as it passes through matter
attenuation
greatest source of scatter in radiography
the patient
during fluoro, greatest source of occupational exposure
compton effect
at what angle from the patient will you receive the least amount of radiation
90 degree angle, right angle, perpendicular to
every time an x-ray photon gets scattered, it will leave with how much of its original intensity
1/1000th, .001, .1%
primary source of patient radiation exposure
photoelectric interaction
interaction that is the source of biological damage for the patient
photoelectric absorption
at 70 kVp __% of x-rays undergo coherent scattering
3%
approximately __% of x-rays incident on the patient reach the IR
1%
t/f atomic number of tissue increases the amount of scatter
false
what is the unit of absorbed dose
gray
what is the unit of absorbed dose equivalent
sievert
rad to gray conversion
x .01
rad to mGy conversion
x10
quality factor for gamma rays
1
quality factor for beta particles
1
quality factor for protons
5
quality factor for fast neutrons
10
quality factor for alpha particles
20
meaning of KERMA
kinetic energy released per unit mass
measures the number of ionizations in air
exposure (C/kg)
measures the energy of ionizations in the air
air kerma (Gy)
used to compare risk of cancer based on different types of radiation and different types of tissue
effective dose
which dose response relationship is radiation protection standards based on
linear non-threshold
which dose response relationship is diagnostic x-ray
linear non-threshold
what is the single most radiosensitive cell in the body
lymphocyte
ability to produce biological damage
relative biologic effectiveness (RBE)
what is the relationship between RBE and LET
directly proportional
radiation interaction with water is called
radiolysis
percentage of the body that is water
80 ish %
cell dies without attempting to divide (2 names)
interphase death or apoptosis
cell division is known as
mitosis
germ cell division is known as
meiosis
dose required for mitotic delay
.01 Gy or 10 mGy
dose required for reproductive failure
1-10 Gy
which part of the eye is most radiosensitive
lens
what dose to the eye will cause partial or complete vision loss
2 Gy
what dose will cause skin erythema
2 Gy
what dose will cause epilation (hair loss)
3 Gy
dose for female sterility temporary and permanent
2 Gy temp, 5 Gy permanent
dose for male sterility
.1 Gy depressed sperm count, 5-6 Gy permanent
what dose can result in genetic mutations
100 mGy or .1 Gy
cancer causing agents are called
carcinogens
dose required for hemopoietic syndrome
1-10 Gy to whole body
when does death occur for hemopoietic syndrome
3-6 weeks after exposure
dose required for gastrointesinal syndrome
10-50 Gy
when does death occur for gastrointestinal syndrome
1 week following exposure
dose required for CNS death or cerebrovascular syndrome
50 Gy
when does death occur for CNS syndrome
death within hours or days
as the complexity of the system increases, what happens to threshold dose and survival time
complexity increases, threshold increases, survival time decreases
minimum filtration for 70 kVp and above
2.5 mm Al equivalent
how do you reduce ESE to vitally sensitive organs
turn back to the beam (skin exposure)
minimum filtration for below kVp
.5mm Al eq
minimum filtration 50-70 kVp
1.5 mm Al eq
digital imaging eliminates retakes due to overexposure of up to ___% and underexposure up to ___%
500% over, 80% under
ALARA meaning
as low as reasonably achievable
body part thickness to use a grid
10 cm thick
good middle ground pulse per second for fluoro
7.5 pps
minimum lead equivalent required for lead aprons
.25 mm Pb
recommended and most widely used lead thickness for shielding
.5mm Pb
what percentage of radiation is blocked at .5mm Pb at 75 kVp
88%
largest source of natural radiation
radon gas
largest source of artificial exposure
medical imaging
fluoro curtain is what lead thickness
.25 mm Pb
minimum lead equivalent required for lead aprons for use in fluoro
.5mm Pb
primary protective barrier lead equivalent required
1/16 inch, .16 cm, 1.6 mm
primary protective barrier must be how high
7 feet
secondary protective barrier lead equivalent required
.08 cm or .8 mm Pb
fluoro exposure switch must be what type
dead man switch
functional component of TLD
lithium fluoride
how to get readings from TLD
heating up lithium fluoride chip
functional component of OSL
aluminum oxide
how to get readings from OSL
laser light reading luminescence
dose limit for embryo
5 mSv for entire period, .5 mSv for each month
annual whole body exposure limit occupational
50 mSv
annual lens of the eye exposure limit occupational
150 mSv
annual extremity, breast, lung, gonad etc exposure limit occupational
500 mSv
cumulative effective limit occupational
10 mSv x age in years
