Classification of Areas

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Classification of areas:

Radiation facilities are divided into different areas they are controlled, supervised, and uncontrolled areas.  National regulatory bodies are assigned the exposure limits for these areas.

Controlled Area:

A controlled area is a limited access area in which the occupational exposure of personnel to radiation is under the supervision of an individual in charge of radiation protection.  This implies that access, occupancy, and working conditions are controlled for radiation protection purposes.  In facilities that use x-rays for medical imaging, these areas are usually in the immediate areas where X-ray equipment is used, such as x-ray procedure rooms and x-ray control booths or other areas that require control of access, occupancy and working conditions for radiation protection purposes. The workers in these areas are primarily radiologists and radiographers who are specifically trained in the use of ionizing radiation and whose radiation exposure is usually individually monitored.  Controlled area of the radiation therapy, diagnostic radiology and nuclear medicine department should be directed by appropriate signs and posters for safety purposes. If possible, controlled area should be guarded by people in the department.

Figure shows the Radiation warning symbol

Examples of controlled areas are the treatment control room and other areas near to the treatment room may also be designated as controlled areas.

Supervised Areas:

Supervised area is defined as any area not designated as a controlled area, but which occupational exposure conditions are kept under review even though specific protective measures and safety provisions are not normally needed. The areas will be designated with the careful evaluation of dose rate in the particular areas.

Uncontrolled Areas:

Uncontrolled areas for radiation protection purposes are all other areas in the hospital or clinic and the surrounding environment.  Uncontrolled areas are those occupied by individuals such as patients, visitors to the facility, and employees who do not work routinely with or around radiation sources.  Areas adjacent to but not part of the x-ray facility is also uncontrolled areas.


1. The persons authorized to work in controlled areas are

a) Radiation Therapist 

b) Medical Physicist

c) Radiation oncologist

d) Dosimetrist

e) All

1. The safety of the controlled is maintained by 

a) Radiological Safety Officer(RSO)

b) Medical Physicist

c) Radiation Oncologist

d) None of the above


1. d) All

2. a) Radiological Safety Officer (RSO)


1. Safety report series 47, IAEA, Vienna

2. The Textbook of Radiological Safety, by Prof. K. Thayalan.


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