In continuation of a series of posts on radiology physics as preparation for the ABR Core Examination, another important set of threshold doses to consider are those for acute radiation syndromes. Acute Radiation Syndrome (ARS), or radiation sickness, is a serious illness that can happen when a person is exposed to very high levels of radiation, usually over a short period of time. Below is a table summary of the three most important ARSs:
|Table 1: Acute Radiation Syndromes|
|Syndrome||Dose||Prodromal Stage Symptoms, Onset, and Duration||Latent Stage||Manifest Illness Stage||Recovery|
|Hematopoietic||> 0.7 Gy||• Anorexia, nausea and vomiting.
• 1 hour to 2 days after exposure.
• Lasts for minutes to days.
|• Lasts 1 to 6 weeks.||• Primary cause of death is infection and hemorrhage.
• Survival decreases with increasing dose.
• Death occurs within a few months after exposure.
|• full recovery for a large percentage of individuals from a few weeks up to two years after exposure.
• death may occur in some individuals at 1.2 Gy
• the LD50/60 is about 2.5 to 5 Gy
|Gastrointestinal (GI)||> 6-10 Gy||• Anorexia, severe nausea, vomiting, cramps, and diarrhea.
• A few hours after exposure.
• Lasts about 2 days.
|• Lasts less than 1 week.||• Death is due to infection, dehydration, and electrolyte imbalance.
• Death occurs within 2 weeks of exposure.
|• the LD100 is about 10 Gy|
|Cardiovascular (CV)/ Central Nervous System (CNS)||>20-50 Gy||• Nervousness and confusion; severe nausea, vomiting, and watery diarrhea; loss of consciousness; and burning sensations of the skin.
• Within minutes of exposure.
• Lasts for minutes to hours.
|• Lasts for hours but often is less.||• Symptoms are return of watery diarrhea, convulsions, and coma.
• Onset occurs 5 to 6 hours after exposure.
• Death occurs within 3 days of exposure.
|• No recovery is expected|