monitoring of equivalent dose to any person occupationally exposed on a
regular basis to ionizing radiation
- risk receiving 10% or more of the annual dose 50 mSv (5 rem) in any single YEAR
- limit month l0.05 mSv (50 mrem)
Personnel dosimetry
first, or primary, dosimeter is to be worn
outside the protective apparel at collar level.
second dosimeter should be worn
beneath a wraparound-style lead apron at waist level.
For pregnant diagnostic imaging personnel
- Primary dosimeter is worn at collar level.
> Second monitoring device is worn at abdominal level.
ring badge is worn as a second monitor when performing radiographic procedures that require the hands to be near the primary x-ray beam
- extremity dosimeter
A thermoluminescent dosimeter (TLD)
Personnel Dosimeters
Characteristics
- Lightweight and easy to carry
> materials durable
> Able to detect small and large exposures - cant be affected
- cheap
Two types of Personnel Dosimeters
Optically Stimulated Luminescence Dosimeter (OSL)
› Direct lon Storage (DIS)
- Most common used for diagnostic imaging and radiation therapy.
- • Contains an aluminum oxide detector.
- Energy discrimination: filters made of aluminum, tin and copper
Sensitivity: accurate reading as low as 10mSv
• Control monitor
Optically Stimulated Luminescence Dosimeter (OSL)
Advantages Optically Stimulated Luminescence Dosimeter (OSL)
Lightweight, durable, easily worn
> Preloaded packet
> Allows for reanalysis
Disadvantages Optically Stimulated Luminescence Dosimeter (OSL)
- Occupational exposure is recorded only in the body area where the devise is attached.
> Exposure cannot be immediately determined
- Small ionization gas filled dosimeter connected to a solid state device with electrically erasable programmable read-only Radiation ionizes the gas
- Radiation ionizes the gas in the chamber and the electric charge will “read out” by introducing a signal
• Read out through a physical connecting device
Direct on Storage Dosimeter
- adventages : Instant access to daa
Lightweight and durable - disadvantage: Must be wom to be accurae
Radiation Survey Instruments for
(Cio) Area Monitoring Three categories :
without a readout scale
> with a readout scale
> Ionization-chamber based
3 Gas-filled detectors :
> lonization chamber-type survey meter (cutie pie)
› Proportional counter
› GM survey meter
Sensitivity ranges and uses
> Advantages and disadvantages
• Proportional Counter
Geiger-Müller Survey Meter
> Sensitivity and use
> Components
> Disadvantages
lonization chamber-type survey meter (cutie pie)
