Lecture 9- Radiation Safety Flashcards
what is the biggest source of radiation to the US momulation
radon or medical imaging
what is the biggest source of radiation to the US momulation
radon or medical imaging
what is the difference between Denver and New ORleans
Denver has more radiation
what is the typical annual radiation to a human
.2mSV
what is cosmic radiation
cosmic ray particles originate from outside the solar system and from solar flares. When striking the earths upper atmosphere, particles are defected by van Allen belts. Radiation at Earths surface includes primary ET radiation secondary radiation showers which are particles from the upper atmosphere having collisions
does radiation decrease with elevation
no it doubles every 5000 feet
is exposure higher with air travel
yes, and frequent fliers
how much extra radiation do airline crews and frequent fliers recieve
1mSv annullay
is radiation higher at equator or poles
it is higher at the poles
what is the dose percent decrease between indoor and outdoor
indoor is 20% less than outside
what is terrestrial radiation
radioactive things in the soli and primordial radionucelotides. Radioactive atoms with half-lives comparable to the age of the earth.
what primordial radio nucleotides are most radioactive
K-40 and uranium 238 and thorium 232
what is beta radiation
it is electrons like aluminum foil
what is beta radiation
it is electrons like aluminum foil
what is the difference between Denver and New ORleans
Denver has more radiation
what is the typical annual radiation to a human
.2mSV
what is cosmic radiation
cosmic ray particles originate from outside the solar system and from solar flares. When striking the earths upper atmosphere, particles are defected by van Allen belts. Radiation at Earths surface includes primary ET radiation secondary radiation showers which are particles from the upper atmosphere having collisions
does radiation decrease with elevation
no it doubles every 5000 feet
is exposure higher with air travel
yes, and frequent fliers
how much extra radiation do airline crews and frequent fliers recieve
1mSv annullay
is radiation higher at equator or poles
it is higher at the poles
what is the dose percent decrease between indoor and outdoor
indoor is 20% less than outside
what is terrestrial radiation
radioactive things in the soli and primordial radionucelotides. Radioactive atoms with half-lives comparable to the age of the earth.
what primordial radio nucleotides are most radioactive
K-40 and uranium 238 and thorium 232
what is alpha radiation
helium nun which is lungs
what is beta radiation
it is electrons like aluminum foil
hw does the radiation from the terrrestrial sources get into the body
into the lungs because partcles are inhaled from the soil
how does radon usually get into the body and what kind of radiation is it
alpha radiatin and it is breathed in
what is the largest background source of radiation
radon
what is radon from and the half life
it is from uranium 238 and it is from alpha decay with a half life of 3.8 days
what building feature is important for radon exposure
ventilation is important
what unit are radon levels measured
it is measured through picoCuries per Liter
what is the disadvantages to film badge
requires processing and no direct readout, and excessive moisture and heat may damage the film
what is the primary internal radiation and where is it found
muscle and pottasium-40
what are the highest source of artificial radiation
medical exposures and mostly diagnostic xrays
what causes cigarettes to be radioactive
they have polonium
what is the dose from cigarettes
it is usually 16- mSV to bronchial epithelium and 13 mSV effective dose. More than a CT
what occupation has the highest occupational exposure and how does that compare to people working in radiology
uranium miners have 12 mSV as dose and radiologists and radiology techs are 1-.7
what is the typical dose for a an interventional radiologist and cardiac cath lab staff
it is 18 and 5
where do you wear a personal dosimeter
front torso when no apron or collar with apron
what are the three main types of peronnel dosimeters
film badges, storage phosphor dosimeters, pocket dosimeters
how does a film badge work
radiation darkens the film proportional to the dose. Energy of radiation is determined by including metal filters in front of part of the film.
what does the report include for film badges
a shallow does (skin dose) and beta radiation. It has a deep dose which is penetrating radiation and includes X-ray
what are the advantages of a film badge
wide recorded exposure range, durable and rugged, permanent record, and economical
what is the range for x-rays and beta radiation of a film badge
xray is 100uSV-15SV
beta radiation- 500uSV-10SV
what is the disadvantages to film badge
requires processing and no direct readout, and excessive moisture and heat may damage the film
what are storage phosphor dosimeteres
includse a material that traps radiation even in excited energy state. Some storage process with trap plus record event and event changing electronstrugcture energy is given off proportional todos record
what materials are used
TLD- lithium fluoride, and OSL which is aluminum oxide activated with carbon. Both types are configured with filters for radiation energy determination
what is the advantage to storage phosphor dosimeters
wide recorded energy range and can be reused. It is 10uSV to 10SV
what is the disadvantage to storage phosphor dosimeters
requires processing-no direct readout, destructive readout for TLD and OSL can be verified by repeating a few times. higher cost than film
what is a pocket dosimeter
used for high exposure situations.
what are the types of pocket dosimeters
G-M tubes, radiation, ion chamber, sensitive diodes
what is the main region for the gas filled detector
it is the geiger muller region draw it and it is the cascade of events happen
what are the disadvantages
initial cost
make a summary chart for these
see slide on the 11 page
how does gas-filled detector work
gas is ionized by radiation ions are collected and converted to signal. Incoming radiation ionizes the gas and converted to electrical signal
how does a scintillator work
there is emission of light from radiation interactions
how does a semi-conductor reactor work
they are semi-conductor crystals of Silcon or geranium with impurities so they act as a diode and allows current flow after a radiation interaction
what are the types of detector in terms of usage
counters, spectrometers, dosimeters
what is a counter detector
determines the number of radiation interactions
what are spectrometers
they determine the energy distribution or spectra of radiation
what are dosimeters in terms of use
determine total energy deposited by many interactions
how does a gas filled detector work
two electrons with voltage applied and radiation forms ion pairs with gas and this charge is collected by electrodes and is calibrated by meter
what is an example of ionization chamber
nuclear medicine survey meter, and x-ray exposure meter
what are the issues with the amount of electrical charge felt by gas-filled detectors
gas filled are different based on electrical charge carried. IF there is not enough voltage then there is too little. Want to hit the proportional region where single is determinedly voltage but area lower were radiation is only factor.
what is the main region for the gas filled detector
it is the geiger muller region draw it and it is the cascade of events happen
what does the detector absorption of radiation depend on
photon energy
detector atomic number
detector density
detector thickness
describe a scintillation detector
it emits UV or visible light after interaction. Interaction raises electrons to excited energy level, light emitted when electrons fall back to lower energy level.
what is the difference between phosphorescence and flourescence
fluoro is prompt emission
phosphorescence- delayed emission
what are trapped electron scintillarotsi
after interaction, electrons remain trapped in excited state until heated or scanned with laser. Thermoluminescent dosimeters- used for personnel Photostimulabel phosphorus used as imaging plates for computed radiography
what are modes of detector operation
current mode which individual interactions are averaged together. Pulse mode each interaction is processed individually. Dead time can be problematic. 2 interactions must be separated by a finite time interval to produce distinct signals. iF a second interaction occurs during the dead time interval following another interaction, it is not counted and may disrupt the operation of the detector
what is dead time for non-paralyzable
it is high interaction rates and detector resprtss an underestimated signal
what is dead time for paralyzable
it is a high interaction rates, detector reports that no radiation is present
detection efficiency is measured by
number detected/number emitted or efficiency= geometric efficiency times intrinstic efficiency
what is geometric efficiency
fraction of photons emitted that reach the detector
what is intrinsic efficiency
fraction of photons reaching the detector that are absorbed
what is geometric efficiency dependent on
it is dependent on size of detector, shape and proximity to the source of radiation
what is the best for increasing geometric efficiency
it is best if it is in a well, so if it is put in a box it is best
what is intrinsic efficiency
it depends on how well the detector absorbs radiation, which is a factor of photon energy, detector atomic number, detector density and detector thickness
what does radiation protection and control depend on
time, distance, shielding
how do you minimize time
minimize the fluoroscopy on time and image acquisition. Exposure should not be activated if unprotected individuals are in the procedure room. Leave the procure room during exposure when possible, particularly image acquisition
how do you control for distance
radiation source is like a point at the center of a sphere. Exposure is determined by the inverse square law
what is the formula for the inverse square law
it is E2=E1(D1/D2)squared
what can you do to help with shielding
material absorebs radiation abd best protection is by distance and shielding.
what are the two types of shields
structural and personnel protection devic
what do we do for CT rooms for structural shields
consider scatter and leakage only, primary beam is always intercepted
what must the exposure no exceed for adjacent to x-ray rooms
50mSV for occupational workings, 1mSVper year for pibic or 20mSV in any hour for for other personnel or public
what is the primary radiation
it is the useful beam
what is the scatter radiation
it is the exposure rate for generally .1% and primary form patient to a 20x20 field size increases with field size
what is the leakage radiation
xray is not in primary beam
what are the design parameters
workload, use factor, occupancy factor, distance,
what is the workload for shield
amount of X-rays produced
what is the use factor for shield
fraction of time the radiation source is directed at specific surface
what is the occupancy factor for shield
fraction of time someone occupies an adjacent area
what is the distance for shield
from source to a specific surgace
what do we do for radiography and fluoroscopy rooms for structural shields
if walls are gypsum, generally added lead is required but concrete or brick may be used
what do we do for mammography rooms for structural shields
generally no lead is needed due to low X-ray energy an minimal scatter
what do we do for CT rooms for structural shields
consider scatter and leakage only, primary beam is always intercepted
what are lead gloves used for
they are used if the hangs are directly in the beam
what is used to protect the thyroid
it is thyroid held and it is used if there is high exposure
what is the mammography program under
MQSA
what is the lead with lead glasses
it is optional use in high exposure situations, and side shields are important, but they can be heavy
what can happen if the intervention radiologist doesn’t protect themselves with eye wear
it can lead to cataracts
what are portable barriers and what are the specifications for it
it is transparent lead-acrylic plates which have .5-1mm lead equivalent. It is flor mounted or ceiling mountd or it can be on wheels. There can be lower body shelved for blocks and back scatter and tube leakage
what can increasing tube filtration do to help
increasing tube filtration minimum HVL of 2.3 mm AL at 80 KVP required added filtration decreases the skin dose
what does colimating to the body part do
it can reduce dose to areas outside the primary beam reduces scatter to improve image contrast
do you shield the patient or use shields only for personell
it can be used for the rest of the patient too
what should you do with source to patient distance
it should be increased to a certain dose so that patient is towards detector
what is the recommended screen film speed
fast speed image receptor screen-film: 400 speed recommended and CR is 200 speed
what should be implemented at the institution to prevent accidents
it is quality control to reduce errors
what does NRC stand for and what does it do
it is the US nuclear regulatory commission- rgulates the nuclear materials, and agreement states can carry out NRC regulation enforcement. Rules include persona exposure monitoring, and radioisotope control and disposal, and personnel training, reporting misadministration
what does the FDA do with this
it regulates radoopharmaceuticals and X-ray equipment maufacturers.
what is the mammography program under
MQSA
what is the dose limit to the whole body
50 mSV
what is the dose limit to the individual organ
500 mSV
what is the dose limit to the eye
150 mSV
what is the dose limit to the skin
500 mSV
what is an effective dose
it is a calculated quantity that reflects the radiation detriment of a non-uniform exposure in terms of a whole body exposure that would yield the same biological. Radiology takes in the radiation sensitivity
what is the dose limit to embyro
5 mSV
what is the dose limit to members of the public
1 mSV
what is ALARA
it is dose limites that are not meant to be indications of what is considered safe. Radiation protection doctrine is ALARA. Radiation exposure is to be kept as low as reasonably achievable
what does ALARA stand for
as low as reasonable achievable
what are patients where patient dose is nescessary
after exposure, a patient discovered that they are pregnant, and research protocols to include the exposure to ionizing radiation, and regulatory requirements for mammography, and estimated skin dose to avoid radiation burns, and general patient requests
what are the organ doses important
it is the dose absorbed by an organ, and energy imparted to organ/mass of organ, and it is used full for organ specific risk estimates/epidemiology, and unites are gray. typical are tends of grets
what is the effective dose used for
it is only for reference phantom. It is organ estimated to these reference phantoms however, the tissue weighting factors are for a reference population of both genders and all ages. It is tissue weighting is not specific to gender but is an average. It has organ doses for these two phantoms are combined to calculate E. While organ dose estimates can be calculated for any phantom model or vowel data set, E is defined only for a singular reference person. E is not defined for any other phantom or person
what is the equivalent dose
absorbed dose time radiation weighting factor
what are the units for equivalent dose
it is from gray to sievert
what is a radiation weighting factor
it is that there are different paths for each
what is the difference between effective dose and equivalent dose
absorbed dose is in the diagnostic and effective dose is different
what does the radiation weighting factor do
it rakes into account the type of radiation
what does into calculating the effective dose
organ estimates, tissue weighting factors, and this means that it is not a physical quantity
how are tissue weighting factors determined
it is for different tissues, the gonards, retinas and breast are more sensitive
what is the MIRD
it is the medical internal radiation dosimetry
what does MIRD do
it is the way that there is a 3D phantom and there is a weight of 70kg. It is good for standard anatomy and development
what is an IRCP
it is a 3D model of things, and it is Ct image that adjusts for form as reference size and mass. It is for male and female. It is CT adjustments for organs. It helps calculate dose limits. Reference for genderless than gonads added
what is the effective dose used for
it is only for reference phantom. It is organ estimated to these reference phantoms however, the tissue weighting factors are for a reference population of both genders and all ages. It is tissue weighting is not specific to gender but is an average. It has organ doses for these two phantoms are combined to calculate E. While organ dose estimates can be calculated for any phantom model or vowel data set, E is defined only for a singular reference person. E is not defined for any other phantom or person
what is E used for
E is for occupational and public protection, but E has changed over time, and the definitions of weighting factors and calculation methodology have changed significantly twice since it was first introduced. E is not a physical parameters than can be measured of validated. E describes the radiation source, not the radiation recipient
E folds together cancer incidence and mortality
what is E not for
it is NOT for estimating cancer risk, rather it is assesses detriment which includes much more than cancer risk. It is NOT for individuals, and not a patient dose, E is not sued for estimating potential numbers of cancers from small doses in a large population
what is the process that this deposits energy in the issue during rad/fluoro
the uncharged particles like photons are transformed into kinetic energy of charged particles. Charged particles directly deposit their energy via excitation ionization or radiation. Energy deposition may be some distance from original interaction- two step reaction
what is air kerma
kinetic energy released in air- one step reaction
what is X-ray tube output
it is karma/mAs it is in units of mGY/mAs.
what is the entrance skin dose
entrance skin dose- entrance skin karma times ratio ( tissue to air) of mass energy absorption coefficients
what is the diagnostic reference levels
DRLs are a form of investigation level used as a simple test to identify situations where patient dose is unusally high. Employ an easily measured and standardized quantity. If consistntly exceeded, a local review of procedures and equipment should be performed. IF possible, dose reduction measures should be taken
what is the entrance dose and effective dose for abdomen AP
entrance 2.6
effective .5
what is the entrance dose and effective dose for extremity
entrance .1
effective
what is the entrance dose and effective dose for skull (lateral)
entrance .7
effective .1
what is the entrance dose and effective dose for bone survey
entrance 17
effective 2.8
what is the entrance dose and effective dose for EXU (KUB+tomo)
entrance 38
effective 3.5
what happens to the dose area product and effective dose for angiography exams
the increase the dose greatly
what is the highest angiography exam
TIPS procedure
does CT have a entrance skin dose
no. it just has an effective dose
what is the compassion of patient specific risk
it is highly realistic virtual models of patients or the specific patients own CT or MRI data to define the tissues in the relevant organs. Performs a Monte Carlo simulation and calculate the organ doses. Refer to reference data on risk per unit absorbed dose to calculate risk on an organ by organ basis
what does BEIR stand for
biological effects of ionizing radiation
