Radiation Detection Devices

Equipment, environmental , personal

Three main radiation survey categories:

_____ survey devices

____ survey devices.

_____ dosimetry devices

Equipment survey device

Checks radiation output and performance of x-ray equipment, such as whether selected kVp or mA/mAs is actually produced

Environmental survey device

Measures radiation or radioactive contamination in an area to protect workers and the public

Personal dosimeter

Tracks the occupational radiation dose received by an individual worker over time

A detector

Radiation must interact with what before it can be measured?

Ionization chamber

A gas-filled detector in which radiation ionizes the gas and creates a measurable electrical current

Ionization chamber is made from

A chamber filled with air or another gas plus electrodes that collect the created charges

gas, measured

Ionization chamber basic sequence Radiation enters __ → ionization occurs → positive ions and electrons form → electrical current is ____

Ionization chambers commonly measure

Exposure, air kerma, radiation output, or dose rate

Pocket ionization chamber

A small personal dosimeter that uses ionization of gas and can be read immediately

immediate reading, exposure

Main advantage of a pocket ionization chamber is the ___ ____ of occupational radiation ___.

Geiger-Müller counter

A gas-filled radiation detector commonly used to detect radioactive contamination

A gas-filled tube with electrodes that collect ionization produced by radiation

Geiger-Müller counter is made from and how does it detect radiation?

Radioactive contamination in the environment

Geiger counter — what is it mainly used to detect?

Scintillation detector

A detector that converts radiation energy into flashes of visible light, which are then converted into an electrical signal

Scintillation crystal, photocathode, photomultiplier tube (PMT)

Scintillation detector — what are the key parts in order?

delete

delete

Scintillation crystal

A crystal that absorbs radiation energy and produces tiny flashes of visible light

Photocathode in a scintillation detector

Converts light photons into electrons

Photomultiplier tube PMT

Amplifies the weak electron signal produced after scintillation light reaches the photocathode

Radioactivity/counts, measure photon energy

Main use of scintillation detectors

1,

2.

Counts per minute;CPM; counts per second; CPS

Number of radiation events detected during a period of time

Becquerel Bq

Unit of radioactivity equal to one nuclear disintegration per second

Photon Energy

Gamma/photon spectroscopy — what does it measure?

Semiconductor detector

A solid-state detector in which radiation directly creates mobile electrical charge in a semiconductor material

Solid semiconductor crystal; rad creates electrical charge directly in the crystal,

Semiconductor detector — what is it made of and how does it work?

crystal, amplifier

Semiconductor detector basic sequence: Radiation → semiconductor ___ → electrons and holes are produced → electrical signal → .__→ measurement

accurately,energy resolution

Two main advantages of semiconductor detectors: They can measure photon energy very___ and provide good ___ ___

Examples of semiconductor detector uses

Handheld survey meters, x-ray testing equipment, some AEC systems, digital detectors, and photon spectroscopy

Thermoluminescent dosimeter; LiF + HEAT + light

TLD — what does it stand for and how is it read?

Thermoluminescent crystal; lithium fluoride; LiF

TLD is made from:

crystal, heats, proportional

How a TLD works: Radiation energy is stored in the _ → the reader __ it → visible light is released → amount of light is___ to dose

heat, light

Thermo = __ ; luminescent = __

Main limitation of TLD

Stored signal can fade over time and the reading generally empties the stored information, so it is usually read once before reset

Optically Stimulated Luminescence; OSL = Al₂O₃ + LIGHT + can be reread

OSL — what does it stand for and how is it read?

OSL

What is made of Aluminum oxide Al2O3 crystal?

crystal, light, released, proportional

How an Optically Stimulated Luminescence dosimeter (OSL) works: Radiation energy is stored in the __ → laser or _ __ stimulates it → visible light is __ → amount of light is — to dose

Main advantage of OSL

More sensitive to low radiation doses and can be reread multiple times

HEAT, LiF, LIGHT Al2O3

TLD is read with ___ and commonly uses ___ ; OSL is read with ___ and commonly uses ____

Workers likely to receive 10% or more of the annual occupational dose limit

Who is required to wear an occupational dosimeter?

Personnel dosimeter placement with a lead apron

Usually worn at the collar outside the lead apron

Fetal dosimeter placement for a declared pregnant worker

Worn at waist or abdominal level under the lead apron

delete

delete

delete

delete

delete

delete