Committed dose equivalent (CDE)

Measure of radiation dose to a specific organ or tissue

Committed dose equivalent (CDE) is a measure used in radiation protection to quantify the radiation dose received by a specific organ or tissue over a period of time, typically 50 years for adults and up to age 70 for children, following an intake of radioactive material. It is an important concept in assessing the potential health risks associated with internal contamination by radionuclides.

Definition

The committed dose equivalent is defined as the dose equivalent that will be received by an organ or tissue over a specified period of time after the intake of radioactive material. It is expressed in sieverts (Sv) or rem (1 Sv = 100 rem).

The CDE is calculated using the following formula:

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

where:

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

Calculation

The calculation of the committed dose equivalent involves several steps:

1. Identification of Radionuclides: Determine the types and amounts of radionuclides that have been taken into the body. 2. Biokinetic Models: Use biokinetic models to estimate the distribution and retention of radionuclides in the body over time. 3. Dose Coefficients: Apply dose coefficients, which are factors that relate the intake of a radionuclide to the dose received by an organ or tissue. 4. Integration Over Time: Integrate the dose rate over the specified time period to obtain the committed dose equivalent.

Applications

The committed dose equivalent is used in various applications, including:

• Radiation Protection: To assess the potential health risks from internal contamination and to establish safety standards and guidelines.
• Medical Treatment: In the management of patients who have been exposed to radioactive materials, to evaluate the need for medical intervention.
• Environmental Monitoring: To assess the impact of radioactive releases on human health and the environment.

Regulatory Standards

Regulatory bodies such as the International Commission on Radiological Protection (ICRP) and the United States Environmental Protection Agency (EPA) provide guidelines and standards for acceptable levels of committed dose equivalent to ensure public and occupational safety.

Also see

• Effective dose
• Equivalent dose
• Radiation protection
• Sievert
• Rem