xray production requires what

source of free electrons, acceleration of electrons, focusing of electrons, decceleration of electrons

where does the source of free electrons come from

the filament at the cathode end

what are the two interactions that happen at the target

bremmstrahlung or characteristic

xrays that are produced by the xray tube and strike the patient

primary beam (bremm or characteristic)

what three interactions occur in diagnostic radiography

photoelectric, coherent, compton

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radiation safety- br

radiation safety- BR

Question	Answer
in terms of technical factors how can we reduce pt dose	use higher kvp and lower mAs
what is the number one interaction that causes occupational dose	compton scatter
does 72 SID over 40 SID reduce or increase pt dose	reduce
which generator will have the least pt dose	high frequency
xray production requires what	source of free electrons, acceleration of electrons, focusing of electrons, decceleration of electrons
where does the source of free electrons come from	the filament at the cathode end
what is the filament made of	tungsten
the cathode end is comprised of	filament and focusing cup
as the filament is heated up this process is called	thermionic emission
electrons fall from being heated up forming an	space charge
electrons accelerate from the _ to the _	cathode to the anode
what forces the electrons across the tube	kVp
the higher the kVP the _ energy	more
how are the electrons that are accelerated focused	focusing cup
what is the focusing cup made of	molybdenum or nickel
the anode is made of	tungsten
what is the atomic number of tungsten	74
what is the importance of the high atomic number of the anode	high melting point
decceleration is done by	the anode
what are the two interactions that happen at the target	bremmstrahlung or characteristic
which interaction has the cascade effect	characteristic
x ray production happens where	in the tube at the anode
braking radiation refers to	bremmstrahlung
90% of all x ray production are done through	bremm
below 70 kvp _ % of xrays are bremm	100%
what is the binding energy of the k shell in tungsten	69/70
the higher the energy of the xray the _ the frequency	higher
frequency is measured in	Hertz
the number of times per second the electric and magnetic fields generate themselves	frequency
the distance the xray travels during one regeneration of electric and magnetic fields	wavelength
frequency and wavelength are _ related	inversely
low frequency would be _ wavelength	long
if you increase kvp the frequency _ and the wavelength _	increase, short wavelength
energy and frequency are _ related	directly
penetrability is determined by	kVP
the higher the kVp the _ the quality of the beam	higher
what determines the qauntity of the beam	mAs
xrays that are produced by the xray tube and strike the patient	primary beam (bremm or characteristic)
the beam that passes through the patient and hits the IR	remnant beam
when the distance is doubled intensity is	decreased by 4
when the distance is cut in half intensity is	increased by 4x
what is the inverse square formula	I1/I2= D2^2 / D1^2
xrays travel	in straight lines
xrays travel at the speed of	light
what three interactions occur in diagnostic radiography	photoelectric, coherent, compton
what interaction is the least likely to occur	coherent
in compton energy is _ absorbed	partially
when an electron in knocked out of orbit this is termed	ionization
seen as fog at the IR	compton sscatter
compton is the source for _ dose	occupational
as the photon scatters in compton it has _ energy then how it came in	less
photoelectric effect happens when an _ shell electron is knocked out of orbit	inner shell
the ejected electron in photoelectric is termed the	photoelectron
_ absorption happens in photoelectric effect	total
reduction in intensity of the xray beam as result of absoprtion, scatter, and divergence	attenuation
the higher the atomic number the _ the attenuation	greater
attenuation has _ relationship with IR exposure	indirect
number of ionizations in air	exposure
exposure is calcuated in	coulomb/kg
measures the energy of ionization in air	air kerma
air kerma is measured in	Gy
1 gray = _ j/kg	1
the energy absorbed in matter per unit mass	absorbed dose
mGy is _ of Gray	1/1000
when you increase the mA, intensity _, exposure and air kerma _ , and absorbed dose _	increase
increase in distance will _ absorbed dose	decrease
dose that accounts for radiation type	equivalent dose
most harmful type of radiation	alpha
xray weighting factor is	1
how do you find equivalent dose	Absorbed dose x radiation Weighting factor
dose that takes into account the type of radiation the pt was exposed to as well as the body part	effective dose
how do you find effective dose	absorbed dose (Gy) x radiation weighting factor x tissue weighting factor
effective and equivalent dose are measured in	sievert
who published scientific research recommendations on radiation protection and measurements in the US	NCRP
NCRP 160 addresses	radiation exposure to all sources to people living in the US
what is the largest source of natural radiation	radon
what medical imaging produces the largest amount of radiation	CT
what is the annual dose limit for occupational workers	50 mSv
occupational dose limit for the lens of the eye is	150 mSv
occupational dose for other extremities	500 mSv
public dose limit annually for infrequent exposure	5 mSv
public dose limit annually for continuous expsoure	1 mSv
what is teh dose limit for the public for lens of the eyes	15 mSv
what is the dose limit for the public for extremities	50 mSv
NCRP 116 states guidelines for	occupational vs public dose
NCRP 102 states guidelines for	technology, equipment, room design, shielding
for entire gestation the dose limit is	5 mSv
what is the dose limit for emrbyo fetus exposure for a month	0.5 mSv
annual effective dose for students below 18	1 mSv
what are the cardinal rules of radiation protection	time, distance, shielding
number one way to decrease our dose is	distance
secondary radiation would be	scatter
leakage radiation comes from	the xray tube housing
the maximum allowance for leakage radiation is	1 mGy/hr at 1 meter
the least amount of scatter is at a _ degree angle from the patient	90
if you increase kvp scatter will	increase
if you increase the FOV scatter will	increase
if you increase collimation scatter will	decrease
as pt size increases the amount of scatter _	increases
for fluoro the II is	above the pt
exposure switch on a portable should be a	dead man type
the cord on the portable should be	6 ft (1.8m )
which NCRP outlines the shielding thickness	NCRP 102
aprons, thyroid shields, are mm	.5 mm
glasses should _ mm Pb	0.35
gloves, protective curtains, and bucky slot cover should be _ mm Pb	.25
_ mm PB is required, _ is recommended for fluoroscopy	.25 mm, .5 mm
the xray source in a fluoro room is positioned	below the pt
the primary barrier is	anywhere where the primary beam is directed- wall behind the bucky and floor below the table bucky
the primary barrier thickness must be	1/16th inch lead or 1.6
what is the secondary barrier	doors, control booth
secondary barrier thickness should be	1/32 inch lead or .8mm
for the primary barrier the height from the floor must extend to	7 ft (2.1 m)
areas where personnel are not provided radiation exposure monitors	uncontrolled area
occupational workers that may exceed _ of the annual limit must wear personal dosimeters	10%
type of dosimeter that provide immediate personal readout	pocket ionization chamber
geiger counter is used for	immediate environment reading most commonly for contamination
what is the purpose of a scintillator	convert xray energy into visible light
what is the difference between semiconductor and scintillator	semiconductor takes the xrays and transmits it to electronic signal without converting to light
cumulative effective dose can be calculated by	10 mSv x age
radiation monitor should be worn	on the collar outside the apron at chest level
pregnant technologists should wear an additional dosimeter placed	at the waist under the lead apron
describe film badge	contains small piece of radiographic film, cheap, provides permanent record
thermoluminescent dosimeter (TLD) contains	lithium fluoride
how does TLD work	crystals are heated giving off light in proportion to exposure
do TLD have permanent record	no
what is the concern with the pocket dosimeter	false positive / negative concern
OSL dosimeter is made of	aluminum oxide
how does OSL work	al oxide is exposed to a laser and emits visible light in proportion to radiation exposure
who should review dosimetry reports	physicist and reviewed by staff
how often should I as the tech view my dosimetry report	quarterly
"m" on dose records means	minimal dose
occupational dose records should be kept how long	lifetime
the facility should keep the dose records for	3 years
a document that provides workers with procedures for safely handling or working with a particular substance	material safety data sheet (MSDS)
the process of boiling off electrons is termed	thermionic emission
what accelerates the electrons toward the anode	kvp
what percent of xrays are heat	99% heat, 1% xray photons
xray beam divergence for 72 inch SID is	1 degree per inch
xray beam divergence for 40 inch SID is	2 degrees per inch
do photons have mass	no
how does the xray beam travel	in a diverging beam
what produces the white areas on an image	photoelectric effect
where does compton/photoelectric interactions occur	at the patient
ionziation of water is termed	radiolysis
attenuation is dependent upon	tissue density, atomic number, thickness, xray energy (kvp)
list least to most attenuating	air, fat, water/tissue, muscle, bone
other words for stochastic would be	random, probabilistic, non-threshold, cancer, genetic mutations
other words for determinstic would be	predictable, tissue response, threshold, cataracts, skin erythema
cancer would be a _ effect	stochastic
besides cancer what else would be considered stochastic	embryologic / birth defects
short term deterministic effects include	ARS, epilation, nausea, fatigue, vomiting, erythema
long term deterministic effects include	cataracts, fibrosis, organ atrophy, loss of parenchymal cells, reduced fertility, sterility
leukemia latency is	5-7 years
what is the difference between direct and indirect effects	direct interact with the DNA and damage it- this is less common indirect is where radiaiton interacts with water molecules that break apart then cause damage to DNA
somatic affects	cells
genetic effects affect	germ cells, offspring (genetic mutations which can lead to cancer)
what are the 3 ARS	hematopoietic GI Cerebrovascular
for hematopoietic what is the dose amount	1 Gy
fever/lethargy, death due to infection of hemorrhage within 1-2 month would be what ARS	hematopoietic
what is the dose for GI ARS	greater than 10 Gy
what is the Gy for cerebrovascular ARS	greater than 50 Gy
which ARS has the most severe response	cerebrovascular
in the prodramal phase what happens	bodys initial reaction to high dose of exposure - symptoms can occur within hours and then subside anorexia, nausea, vomitting, diarrhea
in the latent phase what happens	symptoms appear to have resolved lower dose would be a long phase
what happens in the manifest phase	full onset of systemic illness
what is the last ARS phase	recovery or death
for humans the LD 50/60 is	3-4 Gy
according the the Law of Bergonie and Tribondeau radiosensitivity is determined by	mitotic activity (rate of division) specialization maturity
which is more sensitive lymphocytes or nerve cells	lymphocytes
which is worse acute radiation dose or chronic	acute - body does not have time to repair
lethal effects are most likely to happen in what pregnancy stage	preimplantation (0-10days)
cerebral effects such as decreased IQ is likely to happen in what pregnancy stage	fetal
teratogenic effects (physical) are likely to happen in what pregnancy stage	organogensis (10 days - 6 weeks)
radiation induced cancer development is termed	carcinogenesis
energy deposited per micrometer of tissue	linear energy transfer LET
as LET increases damage	increases
do xrays have a high or low LET	low
compares radiation differences in biological effects	relative biological effectiveness
the higher the RBE the _ likley it is to cause biologic harm	more
hypoxia has _ sensitivity	less low oxygen
anoxia has _ sensitivity	minimal no oxygen
defines how a type of radiation plays a role in radiosensitivity in oxygenated cells	OER
more oxygen = _ sensitive	more
highly sensitive tissue types would be	bone marrow, breasts, lungs, colon, stomach
low tissue sensitivity would be	brain, kidney, muscle
the shielding required to reduce the beam intensity to 50% of its original value	HVL
a controlled area would be	control room / tech area
walls to public areas would be considered	uncontrolled area
major disadvantage to AEC	positioning dependent
use grids when thickness is	over 10 cm
main purpose of filtration	reduce pt exposure - removes the soft xrays
according to NCRP 102 at 70 kvp there should be how much filtration	2.5 mm
what is filtration typically made of	aluminum or copper
ABC is used for	adjusts the mA/kvp to compensate for changes part thickness while maintaining brightness
mobile xray would include	c arm and the portable
what are ways in fluoro that we can minimize pt exposure	collimation, last image hold, intermittent or pulsed, removing the grid
max mA for fluoroscopy is	1-5
the exposure timer will go off every	5 minutes
for boost the exposure rate is	10 mGy / min
for low dose the exposure rate is	1-3 mGy / min
does mag mode increase pt dose	yes- focial point moves closer to the photocathode
what are the pros of mag mode	better spatial resolution better contrast resolution
what is the input phosphor made of	cesium iodide
the input phosphor converts	xrays to light
what is the photocathode made of	cesium antimony compound
what does the photocathode do	converts light to electrons
the electrostatic focusing lens have a _ charge	negative
what is the function of the electrostatic focusing lens	forces teh electrons into a concentrated beam
the output phosphor is made of	zinc cadmium
what does the output phosphor do	converts electrons to light
source to skin distance for mobile is	12 in - 30 cm
source to skin distance for stationary is	15 in 38 cm
what is the role of a rectifier	converts AC to DC for tube operation
what is the role of the step up transformer	increases voltage to kvp - mutual induction
what is the role of the step down transformer	reduces voltage
incoming voltage on the xray circuit should be	220 V
xrays exit through the	tube window
as kvp increases the chances of photoelectric effect	decreases
coherent must happen at what energy level	10 kev or below
as kvp increases compton effect	decreases
which trimester is the most radiosensitive	1st
what is the 2nd trimester risk	luekemia
interphase cell death is termed	apoptosis
germ cells undergo	meiosis
where are ionization chambers	after the patient before the detector
what is the concern when doing skull or facial bones	lens
what is the concern when doing cervical spine xrays	the thyroid
what is the concern with thoracic spine xrays	breast tissue
do we want to be on the II side or the opposite side	II
dose response curve that we follow	linear non-threshold

Created by: macummins1

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