Radiation Protection

Thursday, May 28, 2015

As professionals of Radiologic Technologist have the important duty is protecting their patients, themselves, and fellow workers from unnecessary radiation exposure. A broad understanding and knowledge of radiation protection is vital for every Radiologic Technologist. Yet, the basic ideologies and useful traits of radiation protection are described in this article, and should be a necessary part of a course in Radiologic Technologist and Positioning. It is the duty of every Registered Radiologic Technologist to constantly ensure that the radiation dose to both the patient and the fellow technologist including their self is kept to as low as reasonable achievable (ALARA).

Units of Radiation:

The units of Radiation Exposure is the Roentgen (R), Roentgen is measurement of radiation exposure in air that is measured by the amount of ionization in a given unit of air.

Units of Radiation Dose (RAD and REM)


Rad and rem are units of dose it is an ionization within the tissue, also define as energy absorbed by tissue. In diagnostic radiology in which x-ray energy is used, the three units can be considered equivalent to 1R = 1 rad = 1 rem. Rads are used mainly for patient doses, and rems are used for radiation protection purposes, such as for reporting workers doses with personnel monitors.

Traditional VS SI Units

The SI system has been the national standard for units of radiation measurement since 1958. Though, just as the United States is slow in converting to the metric system for other measurements, conventional units of radiation measurement such as the roentgen, rad and rem are still in common use in the United States. Both traditional and SI units are used to describe various dose limits.

Xray and Radiologic Technologist Protection

In January 1994. The Nuclear Regulatory Commission (NCR) changed some of the standards regarding maximum permissible doses. The correct term now for maximum permissible dose is dose-limiting recommendations.

Annual Dose Limit

The dose limiting recommendation for occupationally exposed workers is 5 rem or 50 mSv of the whole body effective dose (ED) per year. This 5 rem or 50 mSv, sometimes is referred to as the annual effective dose limit for whole body occupational exposure.
The Effective Dose for the general public is 0.1 rem (1 mSv) per year for continuous or frequent exposure and 0.5 rem (5 mSv) per year for infrequent exposure.

Cumulative Dose Limit

The cumulative lifetime Effective Dose limit for an occupationally exposed worker is 1 rem (10 mSv) times the years of age. For example, a 50 year old X-ray or Radiologic Technologist has a maximum permissible accumulated dose of 50 rem (500 mSv). However, because of the small risk of long term effects of low level radiation, Xray and Radiologic Technologist must limit their exposure to the least amount possible, or even less than the allowable 5 rem (50 mSv) per year.
Exposure to radiation should be monitored for each occupationally exposed worker. If 0.1 rem (1mSv) or more of exposure could potentially be received per year, the area should be supervised by a qualified radiation protection officer.

Minors Limits to Exposure

Persons younger the 18 years old should not be employed in circumstances in which they are occupationally exposed. The Effective Dose (ED) limit for minors is the same as that of the over-all public 01. Rem or 1 mSv per year for continuous or frequent exposure.

Pregnant Technologist Limit:

The pregnant occupationally exposed worker must take all protections possible to keep exposure to the embryo or fetus for as low as possible. The suggested or recommended maximum equivalent dose to the fetus is 0.05 rem, or 50 mrem (0.5 mSV), during any 1st month and 0.5 rem or 500mrem (5mSv) for the gestation period.
Although it is not required, pregnant Radiologic Technologist should wear a second monitoring device at the abdomen area under the lead apron. These monitoring devices must be marked clearly to distinguish the device worn under the apron at the abdomen from that worn at the collar area.

Dose Limit Recommendations Summary

Occupational Workers: (Whole Body Effective Dose (ED)
  • Annual Dose – 5 rem (50 mSv)
  • Lifetime Accumulation – 1 rem (10 mSv) x years of Age

General Population:
Annual Dose

  • 0.1 rem (1 mSv) for frequent exposure
  • .5 rem (5 mSv) for infrequent exposure

Individuals younger then 18 years old:
  • Same as general population dose for infrequent exposure (should not be employed in situations with frequent or occupational exposure)

Pregnant Technologist:
  • A 2nd personnel monitor should be worn under leas apron
  • 0.05 rem (0.5 mSv) during any 1st month
  • 0.5 rem (5 mSv) for gestation period.

Related Post:
Personal Monitoring Devices
ALARA Principle
Patient Radiation Exposure
Picture Archiving and Communication Systems (PACS)

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