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What is personnel dosimetry?
the monitoring of radiation exposure to any person occupationally exposed regularly to ionizing radiation
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By law, radiation monitoring is required if personnel are expected to receive a dose ___% or more of the annual occupational effective dose limit of _____mSv (___rem).
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Health care facilities issue personnel dosimetry devices if a dose of ____mSv (_____mrem) is expected.
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What does a personnel dosimeter provide?
an indication of the working habits and working conditions of diagnostic imaging personnel.
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The unprotected head, neck, and lenses of the eye can receive as much as ___ to____ times more exposure than the protected body trunk.
10 to 20 times
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Placing a dosimeter at the collar level allows for what?
allows for the approximate equivalent dose to the thyroid glad and eyes of the occupationally exposed personnel
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When should a second dosimeter be worn?
- during special procedures, health care facilities sometimes require two seperate monitoring devices
- beneith a lead apron at waist level to measure the equivalent dose to the lower body trunk/embryo-fetus
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When should TLD ring badges be worn?
Should be worn if the hands are expected to be near the primary beam
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What information should be on a TLD ring badge?
- account number
- participants's name and number
- wear date
- indication of hand (R or L)
- ring size
- number of individual ring dosimeter
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What are the characteristics of personnel dosimeters?
- lightweight
- easy to carry
- record small and large doses in a consistent manner
- inexpensive to purchase and maintain
- Unfluenced by weather, humidity, and ordinary mechanical shock
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Types of personnel dosimeters:
- film badges
- optically stimulated luminescent (OSL) dosimeters
- pocket ionization chambers
- thermo luminescent dosimeters (TLD's)
- extremity dosimeters (TLD ring badges)
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Film badges are:
- still used today
- economical
- composed of 3 parts:
- -durable/lightweight plastic film holder
- -assortment of metal filters
- -film packet
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Film badges sensitivity is from ____mSv (____rem) to as high as _______ mSv (_____rem).
- 0.1 mSv
- 10 rem
- 5000 mSv
- 500 rem
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What is the minimum for film badges reported on Landauer Report?
0.1 mSv (10 mrem)
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What does a film badges densitometer read?
reads the degree of blackening of the film from radiation exposure.
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What is a control badge?
serves as a basis of comparison with remaining film badges after they have been returned to monitoring company (if a control badge has a reading during transport, the reading is subtracted from the batch of badges)
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From data, the radiation dose can be evaluated as_______, ______, or _________ occupational exposure of each person.
- deep (penetrating)
- eye
- shallow(nonpenetrating)
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What does M represent?
minimum dose
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What does P represent?
OSL dosimeter
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What does J represent?
represents dosimeter for x-ray, gamma, and fast neutron radiation
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What does U represent?
finger badge
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Film badge monitoring reports report what?
cumulative equivalent doses for deep, eye, and shallow radiation exposures for calendar quarter (3 months, the year to date, and lifetime radiation
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What is an inception date?
the month and year the monitoring company bean keeping reports for a given individual
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Personal data that is on film badges:
- participant's ID number
- name
- DOB
- sex
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What is the annual state limit for the whole body (head and trunk), active blood forming organs, and gonads?
5,000 mrem (total effective equivalent dose)
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What is the Harvard goal for the whole body, active blood forming organs, and the gonads?
500 mrem
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What is the annual state limit of the lens of the eye?
15,000 mrem
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What is the Harvard goal for the lens of the eye?
1,500 mrem
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What is the annual state limit of skin and extremities?
50,000 mrem
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What is the Harvard goal of the skin and extremities?
5,000 mrem
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What is the annual state limit of the embryo/fetus?
500 mrem (9 months)
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What is the Harvard goal of the embryo/fetus?
50 mrem (9 months)
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What is the minimum report level for X-ray or gamma?
1 mrem
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What is the minimum report level for beta?
10 mrem
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How do you convert rem to S?
x.01
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How do you change S to rem?
%.01
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What is the minimum report level for a neutron?
20 mrem fast, 10 mrem thermal
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What is the minimum report level for the fetus?
1 mrem
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What is the minimal report level for rings?
30 mrem
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What are the main advantages of the film badge?
- provides a permanent record of personnel exposure
- economical
- measures x-ray, gamma radiation, and all other beta radiation in a reliable manner
- durable
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Temperature and humidity cause ________ with film badges?
fogging
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How can a film badge be read?
must be shipped to monitoring company for processing
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How long is a film badge to be worn?
1 month
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Quarterly monitoring is.....
available for very low exposure or nonexistent exposure in film badge
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What is an OSL?
optically stimulated luminescence dosimeter for personnel monitoring that provides the best features of tradiational film and TLD's while eliminating someof its disadvantages.
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What should an OSL badge be exchanged?
every 2 months
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This badge contains an aluminum oxide detector layer?
OSL badge
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After exposure to the layer, this badge is read by exposing the layer to laser light which emits frequencies complimentary of the radiation exposure to the badge.
OSL badge
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Where are OSL badges used?
- research
- hospitals
- nuclear power plants
- airports
- etc.
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What is the OSL badge filters made of?
aluminum, tin, and copper which absorb different energy ranges
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This badge allows the monitoring company to discriminate the energy range of exposure of which differnent energy ranges had been absorbed into the filter.
OSL badge
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OSL badges are sensitiva as low as _____mrem for x-ray and gamma ray photons with energies ranging _____ to greater than _____.
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OSL badges maximum measurement of x-ray and gamma ray photons is ______rem.
1000
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OSL badges detect beta particles energies from____ to excess of ____, dose measurements from _______ to ______.
- 150 keV
- 10 meV
- 10 mrem
- 1000 rem
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OSL badges detect neutron energies from _______ to greater than ______ has a dose measurement range from ______ to ______.
- 40 keV
- 35 meV
- 20 mrem
- 25 rem
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What is the most sensitive personnel dosimeter?
pocket ionization chamber
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Contains an ionization chamber to measure radiation exposure.
pocket ionization chamber
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What are the 2 types of pocket ionization chambers?
self reading with a built in electrometer and non-self-reading which requires a special accessory electrometer to read the device
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What does a pocket ionization chamber measure?
mR (ionization in air)
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What are the advantages of the pocket ionization chamber?
- provide immediate readout
- compact, easy to carry, and convenient
- reasonably accurate and sensitive
- ideal for monitoring short procedures
- sensitive in ranges from 0 to 200 mR (2 R)
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What are the disadvantages to the pocket ionization chamber?
- fairly expensive ($150)
- may be inaccurate reading if not read each day
- can be discharged if subjected to mechanical shock which would result in a false reading
- not permanent
- RSO can document if record needed (really hard to get to happen)
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What is a TLD?
thermoluminescent dosimeter
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Looks similar to a film badge?
TLD
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Contains crystalline form of lithium fluoride (LiF)?
TLD
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What are the advantages of a TLD over film?
- LiF interacts with radiation like tissues does
- humidity, pressure, and normal temperature changes do not affect the TLD
- can be worn up to 3 months
- LiF can be reused which makes it more cost effective, even though the initial cost is high (2 x's that of film)
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What are disadvantages of TLD's
- high initial cost
- readout destroys the stored information in LiF
- necessary to use calibrated dosimeters with TLD's because calibrated dosimeters must be prepared and read with each group of TLD's when they are processed
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How is a TLD read?
- As radiation interacts with the lithium fluoride in TLD's, the electrons in the crystalline lattice work are excited to a higher energy level or band.
- In the reader, the excited electrons are exposed to intense heat which causes the electrons to rise to the conduction band.
- At the conduction band, the electrons can return to their normal state once the excess energy is released in the form of visible light.
- The intensity of light is proportional to the amount of radiation exposing the LiF crystals
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What are radiation survey insturments?
they are area monitoring devices that detect and measure radiation
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Indicates the presence or absence of radiation, whereas a dosimeter system measures only cummulative radiation intensity.
detection system
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What are the 3 types of radiation survey instruments for area monitoring?
- ionization chamber-type survey meter (cutie pie)
- proportional counter
- geiger-muller (GM) detector
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What are the requirements for survey insturments?
- easy to cary; one person to operate
- durable even in surgery
- reliable
- interacts with ionizing radiation like tissue would
- detects all common types of radiation
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