The electronic personal dosimeter (EPD) is a modern electronic

dosimeter A radiation dosimeter is a device that measures dose uptake of external ionizing radiation. It is worn by the person being monitored when used as a personal dosimeter, and is a record of the radiation dose received. Modern electronic personal d ...

for estimating uptake of

ionising radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

dose of the individual wearing it for

radiation protection Radiation protection, also known as radiological protection, is defined by the International Atomic Energy Agency (IAEA) as "The protection of people from harmful effects of exposure to ionizing radiation, and the means for achieving this". Expos ...

purposes. The electronic personal dosimeter has the advantages over older types that it has a number of sophisticated functions, such as continuous monitoring which allows alarm warnings at preset levels and live readout of dose accumulated. It can be reset to zero after use, and most models allow near field electronic communications for automatic reading and resetting. They are typically worn on the outside of clothing, such as on the chest or torso to represent dose to the whole body. This location monitors exposure of most

vital organ In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...

s and represents the bulk of body mass. These are especially useful in high dose areas where residence time of the wearer is limited due to dose constraints.

PIN Dosimeter

PIN diode A pin is a device used for fastening objects or material together. Pin or PIN may also refer to: Computers and technology * Personal identification number (PIN), to access a secured system ** PIN pad, a PIN entry device * PIN, a former Dutch ...

s are used to quantify the radiation dose for military and personnel applications.

MOSFET dosimeters

MOSFET dosimeters are now used as clinical dosimeters for radiotherapy radiation beams. The main advantages of MOSFET devices are: 1. The MOSFET dosimeter is direct reading with a very thin active area (less than 2 μm). 2. The physical size of the MOSFET when packaged is less than 4 mm. 3. The post radiation signal is permanently stored and is dose rate independent.

Gate oxide The gate oxide is the dielectric layer that separates the gate terminal of a MOSFET (metal-oxide-semiconductor field-effect transistor) from the underlying source and drain terminals as well as the conductive channel that connects source and drain ...

of MOSFET which is conventionally

silicon dioxide Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

is an active sensing material in MOSFET dosimeters. Radiation creates defects (acts like electron-hole pairs) in oxide, which in turn affects the

threshold voltage The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and drain terminals. It is an important s ...

of the MOSFET. This change in

is proportional to radiation dose. Alternate high-k gate dielectrics like

Hafnium oxide Hafnium(IV) oxide is the inorganic compound with the formula . Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. H ...

Hafnium dioxide Hafnium(IV) oxide is the inorganic compound with the formula . Also known as hafnium dioxide or hafnia, this colourless solid is one of the most common and stable compounds of hafnium. It is an electrical insulator with a band gap of 5.3~5.7 eV. ...

V. S. Senthil Srinivasan and Arun Pandya, ″Dosimetry aspects of hafnium oxide metal-oxide-semiconductor (MOS) capacitor″

Thin Solid Films Volume 520, Issue 1, 31 October 2011, Pages 574–577 and Aluminum oxides are also proposed as a radiation dosimeters.

References

{{technology-stub Dosimeters

PIN Dosimeter

MOSFET dosimeters

See also

References