We have now discussed the four types of medical countermeasures you may encounter in a radiation emergency, and touched upon some basic concepts of triaging patients who may need medical countermeasures. This final segment introduces Clinical Decision Guides, a critical benchmark that can be used by clinicians to determine if medical countermeasures are indicated for a particular patient.

The decision to treat an individual with a countermeasure is complex. Many factors are considered in a physician's decision to treat a patient, including patient age, comorbidities, time after exposure, and availability of resources. Radiation dose and associated health risks after an exposure are generally among the most important considerations.

The Clinical Decision Guide (CDG) is an operational quantity intended to assist physicians who are evaluating whether a patient needs treatment for internal contamination by radionuclides. For most radionuclides, the CDG is defined by the amount, or activity, of radioactive material delivering an effective dose of 0.25 Sv after incorporation into the body. This dose represents about a 1.3% lifetime risk of fatal cancer attributable to the exposure. Radiation measurements from a urine sample above a CDG value suggest the potential for a higher attributable lifetime fatal cancer risk, and may help to inform a clinician's decision on the risks and benefits of starting countermeasure treatment.

The CDG can also be used as a screening level indicating the need for a more comprehensive investigation of the radiation dose received by a patient. A CDG value is specific to a type and formulation of radionuclide, route of exposure, and size of particle - e.g. inhalational exposure to cesium-137). The CDG of children (0-18yrs) and pregnant women is 20% that of adults.

Clinicians can use the CDG, along with many other pieces of data, when deciding whether to treat an internally contaminated patient with a medical countermeasure.

More information about CDGs can be found in the National Council on Radiation Protection and Measurements report number 161 (NRCP 161).


You have now completed the medical countermeasures module.

Thank you for your attention. For more information about many of the topics discussed in this module, please navigate to the additional resources section.