Radiation Monitoring Flashcards
what is the recommendation of personal monitoring?
any persons occupationally regularly to ionizing radiation is recommended
Exposure monitoring of personeel is required whenever radiation workers are likely to risk receiving _ or more of the annual occupational effective dose limit of _ in any single year
10%
5 rem
to ensure that occupational rad exposure level are kept well below the annual EFD limit
personnel monitoring
What provides an indication of the working habits and working conditions of diagnostic imaging personnel
personnel dosimeter
you should place your monitor where
in front of the body at about collar level to apps. the location of max. radiation dose to the thyroid, head and neck
wearing the dosimeter is the responsibility of the
individual wearing the device
the unprotected head, neck and lenses of the eye receive how much more exposure than the protected body trunk
10-20 times more
Extremity dosimeter an example would be and only used for what modality
TLD
Nuke med
be worn by an imaging professional as a _ when performing radiographic procedures that require the hands to be near the primary x-ray beam
second monitor
4 types of personnel dosimetry
- Film badge (oldest) 10mRem (min. dose)-500Rem
- OSL- 1mRem-1000Rem
- PIC- 1mRem-1000Rem
- TLD- most accurate
what are still used and are an economical type of personnel monitoring device
film badges
Film badges record _ radiation exposure accumulated at a low rate over a long period of time
whole body
Film badges are composed of 3 parts
- lightweight plastic film holder
- an assortment of metal fibers (al or copper)
- film packet
what is used to monitor x-ray energy and to apps. the energy of the radiation reaching the dosimeter
assortment of metal fibers for film badges
Radiation-Dosimetry film inside the film badge is sensitive to doses ranging from
10mRem to 500mrem
less than _ go on the dosimetry report as a minimal
10
outside the film packet forms a _ for the dosimetry film
light-free envelope
radiation makes the film to
darken
after processing, the film
darkens (density)
Densitometer is used to measure
density
what measures optical density, which is the intensity of light transmitted through a given area of the dosimetry film it then compares it with the intensity of light on the _ side of the film
densitometer
anterior
this is the way the densitiometer gives its readout of the amount of radiation the badge has monitored
characteristic curve
densitometer is used to measure
optical density along with Equivalent dose
what are sent with new badges to be worn by radiation personnel
control badge
what serves as a comparison with the other badges once the badges are returned to the monitoring company
control badge
control badge should have a _ reading and have never been exposed to radiation
0
what lists the deep eye, and shallow occupational exposure of each person in the facility
personnel monitoring reports
personnel monitoring reports is a record that is kept to keep track of a
persons cumulative dose
whenever a M appears on this report that indicates that the
equivalent dose is below the minimum measurable radiation quantity
when you have employment change you must give your new employer a copy of your occupational dose record in order to keep an accurate record of what
your lifetime dose
5 advantages of film
- maintained by a monitoring co
- cheap to maintain
- monitors x-rays, gamma rays, & all but very-low energy beta radiation
- can tell the difference in radiation in receives
- hard to damage
What are disadvantages of film
temp. & humidity extremes can cause fogging over long pds of time
2. this will cause an inaccurate reading
3. 1 month wear time is recommended
film is most sensitive to photons having an energy level of
50keV
what does OSL stand for
Optically Stimulated Luminescence
OSL contains
aluminum oxide detector
the OSL dosimeter is “read out” by using _ at selected frequencies
laser light
The OSL dosimeter will _ based on how much radiation the monitor receives
glow
OSL can be worn up to
1 year (2 months is recommended)
results cants be found in
1 day
OSL, three filter layers are present
aluminum
tin
copper
for OSL which layer absorbs the least
Al
for OSL, which layer absorbs the best
Cu (copper)
When _ radiation strikes the OSL badge, it would show a pretty similar reading through all of the filters
high-energy
If only low-energy radiation is what the badge is subjected, then the laser readout (Glow Curve) would show
more interaction with the Al
OSL advantages
- better sensitivity
- detects as low as 1mrem
- max equivalent dose for x-ray and gamma ray photons is 100 rem
OSL is ideal for
personnel in low radiation environments and pregnant women
what is uncommon for us to use, looks like a writing pen
pocket ionization chambers
2 types of pocket ionization chambers
self reading and non self reading
Pic advantages
- immediate readout
- easy to carry
- reasonably accurate and are ideal for procedures of relatively short duration
PIC disadvantages
- cost more than $150.
- must be read every day
- provides no legal record
what does TLD stand for
THermoluminescent dosimeter
The TLD looks similar to that of a
film badge
TLD contains
crystalline form of lithium fluoride
What device measures the amount of ionizing radiation by first heating the crystals to free the trapped, highly energized electrons and then recording the amount of light emitted by the crystals
TLD analyzer
TLD advantages
- monitors more accurately
- humidity, pressure, & normal temp changes won’t effect it
- can be worn for up to 3 months
- crystals can be reused
- somewhat cost effective
Lithium Fluoride (LiF) reacts in the same way as
human tissue
TLD disadvantages
- initial high $
- read only once
- readout process destroys the stored info.
what are area monitoring devices that detect and measure radiation
radiation survey instruments
radiation survey instruments indicates
the presence or absence of radiation
Dosimeter system measures only
cumulative radiation intensity
these instruments measure either the total quantity of electrical charge resulting from the ionization of the gas of the rate at which the electrical charge is produced
radiation survey instruments for area monitoring
What are the three different gas filled radiation detectors that serve as field instruments
- ionization chamber (cutie pie)
- Geiger-muller (GM)
- Proportional counter
what detects presence of radiation and a reasonably accurate measurement of the exposure
radiation survey instruments for area monitoring
what are some advantages to radiation survey instruments for area monitoring
- easy to carry
- durable
- reliable and accurate
- interacts similar to the way human tissue reacts
- detects all common types of ionizing radiation
- energy shouldn’t effect the detector
- direction shouldn’t affect the performance of the detector
- should be cost effective
what does the cutie pie measure
exposure rate
cumulative exposure
cutie pie measures specifically
x-ray and gamma ray (1 window)
beta (in another window)
what can measure radiation intensities ranging from 1mr per hour to several thousand roentgens per hour
cutie pie
advantages of CUtie Pie
able to measure a wide rande of radiation exposures within a few seconds
disadvantage of Cutie Pie
- warm up time (w/o wt the meter will drift & will not be accurate)
- can’t measure exposure rates of diagnostic x-ray imaging because exposure times are just too short
what is most commonly used to measure exposure rates (mR/hr) at various distances from a patient who has received radioactive materials for diagnostic or therapeutic purposes
cutie pie
Geiger-Muller is a monitor for
nuclear medicine facilities
what unit is sensitive enough to detect individual particles or photons
Geiger-Muller
Geiger-Muller allows rapid _ and locate lost_
monitoring
radioactive material and low-level radiocontamination
GM detector contains
audible speaker and gas-filled tube or probe
GM detector meter readings are usually obtained in
milliroentgens per hour
GM disadvantages
- meter reading not independent of the energy of the incident photons
- photons of widely different energies cause the instrument to respond quite differently
- can saturate/jam when placed in a very high intensity radiation area giving a false read
detects alpha and beta in a lab setting
proportional counter
