EPD – Electronic Personal Dosimeter
An electronic personal dosimeter is modern dosimeter, which can give a continuous readout of cumulative dose and current dose rate, and can warn the person wearing it when a specified dose rate or a cumulative dose is exceeded. EPDs are especially useful in high dose areas where residence time of the wearer is limited due to dose constraints.
Characteristics of EPDs
The electronic personal dosimeter, EPD, is able to display a direct reading of the detected dose or dose rate in real time. Electronic dosimeters may be used as a supplemental dosimeter as well a primary dosimeter. The passive dosimeters and the electronic personal dosimeters are often used together to complement each other. To estimate effective doses, dosimeters must be worn on a position of the body representative of its exposure, typically between the waist and the neck, on the front of the torso, facing the radioactive source. Dosimeters are usually worn on the outside of clothing, around the chest or torso to represent dose to the “whole body”. Dosimeters may also be worn on the extremities or near the eye to measure equivalent dose to these tissues.
The dosimeter can be reset, usually after taking a reading for record purposes, and thereby re-used multiple times. The EPDs have a top mounted display to make them easy to read when they are clipped to your breast pocket. The digital display gives both dose and dose rate information usually in mSv and mSv/h. The EPD has a dose rate alarm, and a dose alarm. These alarms are programmable. Different alarms can be set for different activities.
- dose rate alarm at 100 μSv/h,
- dose alarm: 100 μSv.
Advantages and Disadvantages of Electronic Personal Dosimeters
Advantages of Electronic Personal Dosimeters
- EPDs are able to display a direct reading of the detected dose and dose rate in real time.
- EPDs have a dose rate alarm, and a dose alarm, which can warn the person wearing it when a specified dose rate or a cumulative dose is exceeded.
- The dosimeter can be reset, usually after taking a reading for record purposes, and thereby re-used multiple times.
- EPDs are capable of measuring a wide radiation dose range from routine (μSv) levels to emergency levels (hundreds mSv or units of Sieverts) with high precision
Disadvantages of Electronic Personal Dosimeters
- EPDs are generally the most expensive dosimeters.
- EPDs are generally large in size.
- EPDs are used to measure and record radiation exposure due to gamma rays, X-rays, sometimes beta particles. For neutrons, TLDs are more capable.
Direct-ion storage dosimeter, DIS, is an electronic dosimeter, from which the dose information for both Hp(10) and Hp(0.07) can be obtained instantly at the workplace by using an electronic reader unit. The DIS dosimeter is based on the combination of an ion chamber and a non-volatile electronic charge storage element.
DIS dosimeter use an analog memory cell inside a small, gas-filled, ionization chamber. Incident radiation causes ionizations in the chamber wall and in the gas, and the charge is stored for subsequent readout. The DIS dosimeter is read at the user’s site through connection to an electronic reader unit. The DIS dosimeter is designed to clip to a breast pocket. The DIS series of personal electronic radiation dosimeters can operate at high dose rates and inside pulsed fields. It’s lightweight, but rugged. The DIS dosimeter represents a potential alternative for replacing the existing film and thermoluminescence dosimeters (TLDs) used in occupational monitoring due to its ease of use and low operating costs.