UNIT 2: Radiation Monitoring Flashcards
When is personnel monitoring of radiation required?
if occupational worker is likely to receive 10% or more exposure of annual limit
What is the annual occupational effective dose limit?
50 msv (5000 mrem/5rem)
Identify the purposes and non purposes of personnel dosimeters
• Purposes: indication of working habits and conditions, determines occupational exposure
• Nonpurposes: does not protect wearer from exposure
Describe how the personnel monitoring device should be worn: with an apron, without an apron, if radiographer is pregnant
• With an apron: at collar level, outside of apron approximate dose to skin, eyes, thyroid
• Without an apron: at collar level, monitors dose to thyroid, head (eyes), neck (skin)
• If the radiographer is pregnant: 1 at waist level under the lead, monitors dose to protected fetus and 1 at the collar
Where is a common location for extremity badges to be worn?
ring on finger
Identify the 3 types of personnel dosimeters currently used to measure individual radiation exposure.
OSL, TLD, lonization chamber
What does OSL stand for?
Optically Stimulated Luminescence
OSL sensing material
Aluminum Oxide
How does the OSL dosimeter work?
Read out by using laser light
OSL advantages and disadvantages
•Advantages: may be worn up to a year, light weight, durable, easy to wear, can be reread
•Disadvantages: occupational radiation exposure is recorded only in the body area where the device is attached
What is the purpose of the control monitor/badge?
Serve as a basis for comparison with the remaining OSL dosimeters after they have been returned to the company for processing
Where should the control monitor/ badge be kept?
radiation free area within an imaging facility
How is the read out of personnel monitoring badges adjusted if the control badge reads higher than zero?
The reading must be subtracted from each of the remaining OSL’s in the batch to ensure accuracy
How can occupation effective dose be determined if a personnel monitoring device is not worn?
they will get an estimated amount based on the occupational worker’s history
What unit of measurement is commonly used on the radiation dosimetry report?
mRem, but can be requested in mSv
What time frames are reported on the personnel monitoring report?
-Monthly, quarterly, yearly, lifetime equivalent
Which personnel dosimeter can be reread?
OSL
Which personnel dosimeter can only be read once?
TLD
Which personnel dosimeter is most common?
OSL
Which personnel dosimeter is an extremity dosimeter?
TLD
Explain what “deep”, “eye”, and “shallow” indicate on a report and which filters are associated with each.
• Eye: radiation equivalent dose to the lens of the eye at a tissue depth of 0.3cm (Tin OSL)
• Shallow: the external exposure of the skin or extremity at a tissue depth of 0.007 cm averaged over an area of 1cm (Aluminum OSL)
• Deep: external whole body absorbed dose determined by a personnel dosimeter at a tissue depth of 1cm (Copper OSL)
Define “M” on the dosimeter report
an equivalent dose below the minimum measureable radiation quantity was recorded during that time
In well-structured facilities, who receives and reviews the dosimeter monitoring report?
Radiation safety officer
T to F: OSL dosimeters can be reread
True
What does TLD stand for?
Thermoluminescent Dosimeter
TLD sensing material
lithium fluoride
How do TLD’s work?
Heat read out
TLD advantages and disadvantages
•Advantages: accurate and reliable, small and light weight, cost effective because it can be reused
•Disadvantages: readings will be lost if not carefully recorded, readout process destroys information stored in TLD which means it cannot serve as a permanent legal record of exposure
How does the Personnel Digital lonization Chamber (DIS) work
Immediate measurement and read out available when connected to the computer via USB
Personnel Digital lonization Chamber (DIS) advantages and disadvantages
• Advantages: instant access to data, lightweight, durable
• Disadvantages: radiation exposure cannot be determined if dosimeter is not regularly used
Which personnel device(s) are generally “read” every 3 months?
OSL and TLD
Which personnel device(s) are generally “read” daily?
Personnel Digital lonization Chamber
Which radiation survey instruments measure both radiation exposure & exposure rate?
lonization chamber-type survey meter (cutie pie), Proportional Counter
Which radiation survey instruments measure exposure rate only?
GM survey meter
What is known as the “Cutie Pie”
lonization Chamber-Type Survey Meter (gas filled radiation survey instrunment)
lonization Chamber-Type Survey Meter radiation detected
• X-radiation
• Gamma radiation
What is the lonization Chamber-Type Survey Meter used for?
measures radiation exposure and exposure rate to help determine accuracy of radiographic equipment and presence of radiation
lonization Chamber-Type Survey Meter advantages and disadvantages
•Advantages: the ability to measure a wide range of radiation exposure within a few seconds over a broad expanse of radiation energies
•Disadvantages: delicate detector of the unit, without adequate warm-up time it can produce an inaccurate reading
Which is the instrument of choice when determining exposure rates from patients containing therapeutic doses of radioactive material and measuring rates in radioisotope storage facilities?
lonization Chamber-Type Survey Meter
Proportional Counter radiation detected
alpha and beta
Proportional counter uses
No useful purpose
Geiger-Muller Survey Meter radiation detected
Sensitive, able to detect individual particles except alpha particles. Can also detect photons.
Geiger-Muller Survey Meter uses
• can detect area contaminated by radioactive material
• locate radioactive source
Geiger-Muller Survey Meter advantages and disadvantages
•Advantages: offers rapid monitoring, scan radiation barriers and detect defects
•Disadvantages: unless corrected, provides wrong readings, likely to saturate or jam when placed in pulsed high intensity radiation area
Which survey meter is most used in Nuclear Medicine
GM survey meter
Which type of equipment can be used to measure radiation output from radiographic & fluoroscopic equipment?
Ionization Chamber-Type Survey Meter
List the annual measurements that must be performed as required by the state, federal, and healthcare accreditation organizations for radiographic/ fluoroscopic devices
•X-ray output in Gy or mGy
•Fluoroscopic radiation entrance rates in mSv/min or R/ min
•kVp setting accuracy
•Exposure timer exactness
•Half-value layers or beam quality
Ionization chambers are used to measure radiation output from which unit?
X-ray unit and Fluoroscopic unit
What is the radiation safety officer responsible for
Reviewing personnel reports and maintaining a radiation safety program
To keep radiation exposure ALARA, most health care facilities issue dosimeter devices when personnel could receive approximately:
1% of the annual occupational EfD limit
