Committed dose

Committed Dose

The committed dose is a measure used in radiation protection to quantify the radiation dose received by an individual over a specified period of time, typically 50 years for adults and up to age 70 for children, following an intake of radioactive material. This concept is crucial in assessing the long-term health risks associated with internal contamination by radioactive substances.

Definition

The committed dose is the total radiation dose that will be received by an individual from an intake of radioactive material over a specified period. It is expressed in sieverts (Sv), which is the SI unit for dose equivalent. The committed dose takes into account the type of radiation, the energy of the radiation, and the biological effect of the radiation on different tissues and organs.

Types of Committed Dose

There are several types of committed dose, depending on the context and the specific organs or tissues considered:

• Committed Effective Dose (CED): This is the sum of the committed equivalent doses to all tissues and organs, each multiplied by a tissue weighting factor. It provides a measure of the overall health risk from the intake of radioactive material.

• Committed Equivalent Dose (CEDT): This is the dose to a specific tissue or organ over the specified period. It is used to assess the risk to particular organs that may be more sensitive to radiation.

Calculation

The committed dose is calculated using the following formula:

\[ H_T(t) = \int_0^t \dot{H}_T(t') \, dt' \]

where:

• \( H_T(t) \) is the committed equivalent dose to tissue \( T \) over time \( t \).
• \( \dot{H}_T(t') \) is the dose rate to tissue \( T \) at time \( t' \).

The calculation involves integrating the dose rate over the specified period, taking into account the biological half-life of the radioactive material in the body and the physical half-life of the radionuclide.

Importance in Radiation Protection

The concept of committed dose is essential in the field of radiation protection, particularly in the context of occupational exposure and environmental contamination. It helps in:

• Assessing the long-term health risks associated with internal contamination.
• Establishing safety standards and limits for exposure to radioactive materials.
• Guiding the design of protective measures and interventions to minimize exposure.

Regulatory Framework

International organizations such as the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency (IAEA) provide guidelines and recommendations for calculating and interpreting committed doses. These guidelines are used by national regulatory bodies to establish legal limits and safety standards for radiation exposure.

Also see

• Radiation protection
• Sievert
• Internal contamination
• International Commission on Radiological Protection
• Radiation dose