Unit 4 Radiation Protection - Rad Monitoring

What is radiation monitoring used to ensure in terms of occupational radiation exposure levels?

Ensure occupational radiation exposure levels are kept well below the EfD limit (annual effective dose - 50 mSv)

What “monitors the equivalent dose to any person occupationally exposed on a regular basis to ionizing radiation”?​

Personnel dosimetry

When is Personnel Dosimetry required to be used?

A likelihood that an individual will receive more than 10% of the recommended annual dose of 50 mSv ​

To keep with ALARA concept, most facilities issue devices when personnel might receive how much percentage of occupational dose?

1%

What “Provides indication of working habits and conditions of imaging personnel”?

Personnel Dosimeters​

What “provides occupational exposure​, measures the quantity of ionizing radiation exposure​”?

Personnel Dosimeters​

Are Personnel Dosimeters a method of protection from radiation?

NOT a method of protection

During diagnostic radiology, where should the badge should be worn?

Collar level facing forward on the anterior side of the individual

When wearing a lead apron, where should the radiation badge be worn?

Collar level on the outside of the apron​

During high level studies, if a second monitor is worn with an apron, where should it be placed?

Inside apron at waist level​

Where should an Embryo-fetus monitor​ be worn?

Inside the lead apron at the waist level

When is an Extremity dosimeter​ used?

When hands are required to be in the primary beam

What type of badge is “used in calculating monthly occupational doses”?

Control badges

Where is a Control badge kept in order to have background radiation measured?

Distant, radiation-free area, reading of minimal to zero (background radiation)​

What is the mrem deep dose number for ALARA I (calendar quarter)?

125 mrem deep dose​

Which ALARA investigation involves advisement from the RSO?

ALARA I

What is the deep dose mrem number for ALARA II (calendar quarter)?

375 mrem deep dose​​

Which ALARA investigation requires a member of the RSO staff will investigate reasons for high levels​?

ALARA II

What are the characteristics of badge monitors?

• Lightweight and easy to carry​

• Durable materials to tolerate daily use​

• Reliably detect exposures from small tolarge​

• Not affected by outside influences​

  • Weather​

  • Humidity​

  • Mechanical shock​

• Inexpensive to purchase ​

• Easy to maintain​

What are all the types of Personnel Monitoring?​

• Film Badge​

• OSL​

• TLD​

• Pocket Ionization Chamber​

• Digital Ionization Dosimeter (Old) / Direct Ion Storage Dosimeter (New)​

What type of badge is “not used as often, uses dental film​, and has aluminum and copper filters that allow conversion to tissue dose​”?

Film Badge​

What are the advantages to Film Badges​?

• Cost efficient​ - few dollars a month​

• Provides permanent, legal record​

• Durable if dropped​

• Can determine if exposure is from scatter or primary radiation​

What are the disadvantages to Film Badges​?

• Temps and humidity can cause inaccurate readings by fogging​

• Not recommended to be used more than 1 month​

• Not reusable ​

• Sent out to read​

What does TLD stand for?

Thermoluminescent Dosimeter​

What is a “light free device with crystalline form (powder or small chips) of lithium fluoride that functions as the sensing material”?​

Thermoluminescent Dosimeter

How is energy stored and released in a Thermoluminescent Dosimeter?

• Energy stored by trapping electrons in crystal lattice​

• Crystals are heated, released by the lattice into the conduction band and return to normal state​

• Energy is then released in form of visible light which is measured by a TLD analyzer

Is the light emitted from Thermoluminescent Dosimeter directly or indirectly proportional to exposure?​

Directly proportional

What “Creates a graph of exposure called a glow curve”?​

Thermoluminescent Dosimeter​

What are the advantages for TLDs​?

• Not effected by humidity or normal temperature changes​

• Measures as low as 0.05 mGy​

  • Exposures below that are recorded as minimal​

• Can be worn for 3 months​

• Crystals can be reused after reading which can be cost efficient​

• Has ring option​

What are the disadvantages for TLDs?

• High initial cost and cost of equipment to do reading ​

• Readings can be lost is not carefully recorded because once energy is released from crystals it cannot be reread​

• Records only exposure to area in which it is worn​

What does OSL/OSLD stand for?

Optically Stimulated Luminescent Dosimeter

What is the most common type of device used to monitor occupational exposure?​

OSL/OSLD​
Optically Stimulated Luminescent Dosimeter

What type of layer is an OSL made out of?

Aluminum oxide layer​

What are the 3 filters made up of OSL?

• aluminum (least absorption, shallow)​

• tin (eye)​

• copper (most absorption, deep)​

What are other key points about OSL?

• Electrons are trapped in the detector. Read out is done when dosimeter is struck by laser light. ​

• Releases energy in a form of a light. ​

• Luminescent is proportional to the amount of exposure received​

• Exposures below 0.01 mGy are recorded as minimal​

What is a newer development of OSL called and what is its purpose?

microStar which reads a special OSL dot called a nanoDot

What are the advantages of OSL/OSLD?

• Lightweight, durable and easy to carry & wear​

• Self-contained preloaded packet​

• Not affected by heat, moisture or pressure​

• Has extended wear up to one year​

• Offers complete reanalysis​

• Reasonably inexpensive to purchase and maintain​

• Has ring option – newest technology​

What are the disadvantages for OSL/OSLD?

• Only records exposure to area where it’s worn​

• Sent out to be read ​

• Unless you have a nanoDot version of the OSL/OSLD​

What is a Pocket Ionization Chamber​ also known as?

pocket dosimeter​

What is the most sensitive radiation monitoring badge?

Pocket Ionization Chamber​

What type of electrodes do Pocket Ionization Chambers contain?​

2 electrodes, one positive, one negative charged​

What are the two types of Pocket Ionization Chambers?​

• self reading (contains an electrometer to provide reading) ​

• non-self reading type (requires an accessory electrometer)

What are the advantages of Pocket Ionization Chambers?​

• Provides immediate readout​

• Compact, easy to carry​

• Convenient

What are the disadvantages of Pocket Ionization Chambers?​

• Fairly expensive​

  • $150 per unit​

• Inaccurate if not read daily​

• Can be discharged by amechanical shock​

• No permanent legal record​

What is a Direct Ion Storage Dosimeter​ (DIS) or digital ionization dosimeter?​

• Provides immediate radiation exposure but can also do long term ​

• Contains ionization chamber that produces and stores electrical charge​

How is a readout of a Direct Ion Storage Dosimeter​ (DIS) obtained?

• USB​

• Wireless connection​

• Device wearer’s cellphone app​

• Activates the vendor’s software for reading​

What are the advantages of Direct Ion Storage Dosimeters?​

• Lightweight ​

• Instant access of reports directly to user and stored at facility​

• Doesn’t have to be mailed in​

• Isn’t easily affected by being dropped or bumped​

What is the disadvantage of Direct Ion Storage Dosimeters?​

Not effective if not worn properly​

What is another name for a Record of Personnel Monitoring?​

Radiation Dosimetry Reports

What is the purpose of Radiation Dosimetry reports?

• keep an ongoing tally of employee occupational exposures​

• Results must be recorded and maintained to meet state and federal regulations​

• Records must be kept permanently by facilities ​

• Should retrieve records from previous employers and present them to new employer​

What are the time frame requirements of Personnel Monitoring?​

• Period of time wearing (monthly for RH)​

• Quarterly​

• Yearly​

• Lifetime​

What is a DDE?

Deep dose equivalent​

What is the DDE depth in soft tissue and is it an absorbed dose?

• 1cm depth in soft tissue​

• Absorbed dose​

What does SDE stand for?

Shallow dose equivalent​

What is the SDE depth in soft tissue and what type of dose is it?

• 0.007cm depth in soft tissue​

• Dose to external skin​

What is EDE or LDE?

Eye or Lens dose equivalent​

What is the EDE/LDE depth in the eye and what type of exposure is it?

• 0.3cm depth in the eye​

• Exposure to the lens​

What does CDE​ stand for?

Committed Dose Equivalent​

What is the “total dose received over a period of time, usually during a 50-year period from an inhaled or ingested radioactive material”?​

Committed Dose Equivalent​

What are examples of inhaled or ingested radioactive materials in CDE?​

Radon, contaminated food, absorption through the skin, or injected radioisotopes

How many mSv is the annual dose limit to single organs with CDE?​

500 mSv

What NCRP report contains information about Committed Dose Equivalent?

NCRP 160

What does CEDE stand for?

Committed Effective Dose Equivalent

What “Applies to long term radiation of individual organs or tissue resulting from inhalation or ingestion of long-lived radioactive material (long decay life)”?​

Committed Effective Dose Equivalent

What is the equation for Committed Effective Dose Equivalent?

Sum of all organs (CDE) x weighting factor for importance (tissue weighting factors)​

How is the Committed Effective Dose Equivalent delivered?

slowly over long period of time from an inhaled or ingested material​

What does TEDE stand for?

Total Effective Dose Equivalent

What dose equivalent is defined by the NRC?

Total Effective Dose Equivalent

What is the equation for Total Effective Dose Equivalent?

• Sum of the deep dose equivalent for external radiation and the committed dose equivalent for internal radiation​

• DDE + CDE = TEDE​

What is the annual dose for Total Effective Dose Equivalent?

50 mSv (whole body)

Why is the annual dose for Total Effective Dose Equivalent 50 mSv?

limit the risk cancer, genetic effects, cataracts, skin damage, sterility

What instrument “Detects and measures radiation​; detects the presence or absence of radiation”?

Radiation Surveys Instruments​

What are the requirements for Survey Instruments?​

• Easy to carry and operated by one person​

• Durable enough to withstand normal use​

• Reliable​

• Should interact with radiation similar to human tissue​

• Should be able to detect all types of radiation​

• Energy of the radiation should not affect the detector​

• Should be cost effective​

What are the 3 Gas Filled Radiation Survey Instruments?

• Ionization chamber “Cutie Pie”​

• Proportional counter​

• Geiger Muller (G-M) detector​

What is the Ionization Chamber-Type Survey Meter​ “Cutie Pie”?

Rate (measures the rate of exposure) and survey meter

What is “used for x-ray room installations, measuring scatter from fluoro or CT and calibration”?​

Ionization Chamber-Type Survey Meter​

What can be used “to measure exposure rates coming from patients with therapeutic material​ and to measure doses traveling through protective barriers​”?

Ionization Chamber-Type Survey Meter​​

What are the advantages vs disadvantages of “Cutie-Pie”?

• Advantages​

  • Measures a wide range of exposures in a few seconds​

  • Can be used to calibrate x-ray equipment​

• Disadvantages​

  • Without adequate warm up, could cause inaccurate readings​

  • Large size​

  • Delicate construction​

  • Not good with short exposure times ​

What is “used in laboratories to detect alpha and beta radiation​; detects small amounts of other types of contamination​”?

Proportional Counter​

What detector is mainly used in Nuclear Medicine?

Geiger-Muller (GM) Detector​

What detector easily detects areas of contamination and has an audio signal?​

Geiger-Muller (GM) Detector​

In terms of the Geiger-Muller Detector, the signal _______ as radiation is more _______. (like how a metal detector responds to metal)

increases, intense

How is the Geiger-Muller Detector read?

Reads in counts per minute

What are Safety Features in Radiation Equipment?​

• On and off switches​

  • Power equipment down​

• Interlocks​

  • Detents ​

• Visual- audio monitors​

  • Timer and audible signal​

• Emergency controls​

  • Breakers, stop buttons​

How are onization chambers used in the rate mode?

Calibrate equipment when used with an electrometer

What is “used by medical physicist for standard measurements required by state, federal, and accreditation organizations for x-ray and fluoro units”?

Calibration Instruments​

What are examples of Calibration Instruments?

• X-ray output​

• Reproducibility and linearity of output​

• Timer accuracy​

• Half value layer​

• Beam quality​

• Entrance exposures for fluoro​

• With a calibrated parallel plate chamber it could check mammo equipment​

What are the examples of Calibration Instrument rate percentages?

• Collimation accuracy- 2%​

• SID indication- 2%​

• PBL- 2%​

• Variation in exposure- 5%​

Who performs Equipment Surveys​?

RSO and in writing​

What are kept permanently and indicates if a resurvery is necessary if so when to do?

​Equipment Surveys

How often are performance surveys done?

Annually

What are examples of Equipment Surverys?

• Timer accuracy​

• Exposure reproducibility​

• kVp test​

• Linearity of mAs​

• Tube stability​

• Beam limiting device​

• Timer​

• Primary barrier​

• kVp and mAs indication​

• High levels control​

• Exposure rate limits​