Editing Health physics (section)

==Radiation protection instruments==
Practical ionising radiation measurement is essential for health physics. It enables the evaluation of protection measures, and the assessment of the radiation dose likely, or actually received by individuals. The provision of such instruments is normally controlled by law.  In the UK it is the Ionising Radiation Regulations 1999.

The measuring instruments for radiation protection are both "installed" (in a fixed position) and portable (hand-held or transportable).

===Installed instruments===
Installed instruments are fixed in positions which are known to be important in assessing the general radiation hazard in an area. Examples are installed "area" radiation monitors, Gamma interlock monitors, personnel exit monitors, and airborne contamination monitors.

The area monitor will measure the ambient radiation, usually X-Ray, Gamma or neutrons; these are radiations which can have significant radiation levels over a range in excess of tens of metres from their source, and thereby cover a wide area.

Interlock monitors are used in applications to prevent inadvertent exposure of workers to an excess dose by preventing personnel access to an area when a high radiation level is present.

Airborne contamination monitors measure the concentration of radioactive particles in the atmosphere to guard against radioactive particles being deposited in the lungs of personnel.
    
Personnel exit monitors are used to monitor workers who are exiting a "contamination controlled" or potentially contaminated area. These can be in the form of hand monitors, clothing frisk probes, or whole body monitors. These monitor the surface of the workers body and clothing to check if any [[radioactive contamination]] has been deposited. These generally measure alpha or beta or gamma, or combinations of these.

The UK [[National Physical Laboratory (United Kingdom)|National Physical Laboratory]] has published a good practice guide through its Ionising Radiation Metrology Forum concerning the provision of such equipment and the methodology of calculating the alarm levels to be used.<ref>Operational Monitoring Good Practice Guide "The Selection of Alarm Levels for Personnel Exit Monitors" Dec 2009 - National Physical Laboratory, Teddington UK [http://www.npl.co.uk/upload/pdf/alarm_levels_personnel_exit_monitors.pdf] {{Webarchive|url=https://web.archive.org/web/20130513191645/http://www.npl.co.uk/upload/pdf/alarm_levels_personnel_exit_monitors.pdf |date=2013-05-13 }}</ref>

===Portable instruments===
Portable instruments are hand-held or transportable.
The hand-held instrument is generally used as a [[survey meter]] to check an object or person in detail, or assess an area where no installed instrumentation exists. They can also be used for personnel exit monitoring or personnel contamination checks in the field. These generally measure alpha, beta or gamma, or combinations of these.

Transportable instruments are generally instruments that would have been permanently installed, but are temporarily placed in an area to provide continuous monitoring where it is likely there will be a hazard. Such instruments are often installed on trolleys to allow easy deployment, and are associated with temporary operational situations.

===Instrument types===
A number of commonly used detection instruments are listed below.

*[[ionization chamber]]s
*[[proportional counter]]s
*[[Geiger counter]]s
*[[Semiconductor detector]]s
*[[Scintillation counter|Scintillation detectors]]

The links should be followed for a fuller description of each.

===Guidance on use===
In the [[United Kingdom]] the [[Health and Safety Executive|HSE]] has issued a user guidance note on selecting the correct radiation measurement instrument for the application concerned [http://www.hse.gov.uk/pubns/irp7.pdf] {{Webarchive|url=https://web.archive.org/web/20200315222732/https://www.hse.gov.uk/pubns/irp7.pdf |date=2020-03-15 }}. This covers all ionising radiation instrument technologies, and is a useful comparative guide.

===Radiation dosimeters===
[[Dosimeter]]s are devices worn by the user which measure the [[equivalent dose|radiation dose]] that the user is receiving.
Common types of wearable dosimeters for ionizing radiation include:
* [[Quartz fiber dosimeter]]
* [[Film badge dosimeter]]
* [[Thermoluminescent dosimeter]]
* Solid state ([[MOSFET]] or silicon diode) dosimeter