RADIATION DOSES
/ANNUAL DOSE
LIMITS /
DOSIMETRIC
DEVICES
Dr Zoshia Ali Zaidi
PGR Radiology
CMH Jhelum

Radiation Doses
 Average Yearly Exposure : 200 - 300 mREM
 Lifetime Exposure (80 years) : 16 – 24 REM
 Dental X-Ray : 1 mREM
 Flying in Airplane : 1.5mREM /5 hour flight
 Chest X-Ray : 8 mREM
 CT Abdominal : 500 mREM (2x)
 CT Chest : 500 mREM (2x)
 Whole Body CT : 0.5 – 5 REM (10x)
 Radiation Therapy : 2500 REM (10,000x)

Types of Procedure

Annual Dose Limits
 DOSE LIMITS are recommended by the International Commission on
Radiological Protection (ICRP). They are in place to ensure that individuals are
not exposed to an unnecessarily high amount of ionizing radiation. Dose limits
are a fundamental component of radiation protection, and breaching these
limits is against radiation regulation in most countries.
 The limits are split into two groups, the public, and occupationally-exposed
workers. The following limits are up to date at the time of writing this article
(April 2017)

Occupationally Exposed Workers
 Effective Dose
 20 mSv a year, averaged over defined periods of 5 years with no single year >50 mSv
 The equivalent dose to the lens of the eye
 20 mSv a year, averaged over defined periods of 5 years with no single year >50 mSv 2 (this
was previously 150 mSv a year and updated in 2013)
 The equivalent dose to the skin (averaged over 1 cm2)
 500 mSv in a year
 the equivalent dose to the hands and feet
 500 mSv in a year
 The ICRP recommends that occupational exposure of pregnant women should fall into
the limits similar to that of the public.

PUBLIC
 Effective dose
 1 mSv a year (higher values are permitted if the average over 5 years is not above
1 mSv a year)
 The equivalent dose to the lens of the eye
 15 mSv a year
 The equivalent dose to the skin (averaged over 1 cm2)
 50 mSv a year
 Dose limits do not apply to medical exposures; however, the concept of
radiation protection is still pertinent.

Types of Limit Doses

DOSIMETERY DEVICE
 A radiation dosimeter or badge does not provide protection but detects and
measures radiation that you have been exposed to.The badge will detect
high-energy beta, gamma or x-ray radiation.Dosimeters cannot detect low
energy beta radiation from some isotopes, including carbon-14, tritium or
sulfur-35.
 Devices use to detection of radiations.

Functions
 Energy enters the dosimeter which converts this energy into a signal strength
and an output. The conversion process and the output are unique to each
different type of dosimeter.
 Common output modalities are:
 dose rate: gives an instantaneous value over time
 often used in environmental, radiopharmaceutical and equipment checks
 total dose: the amount of activity over a given time frame
 patient or personal dosimetry

Types of Dosimeters
 charge collection devices: radiation energy is converted to electric charge
(either directly or indirectly) and the dosimeter converts this charge into a signal
output
 gas-filled collectors
 scintillation detectors
 solid-state detectors
 other type: devices made of material that changes on exposure to radiation
energy
 photographic film
 thermoluminescent detectors (TLD)
 optically stimulated luminescent detectors