Evaluating the dose received ACTION TO TAKE IN THE EVENT OF EXTERNAL IRRADIATION The dose received determines the treatment. The biological dosimetry is carried out as quickly as possible once the victims are in hospital care. Physical dosimetry also provides several evaluation possibilities. 15SHEET Responders Medical teams: physicians and paramedical personnel Places Healthcare facility + Biological dosimetry Very early hyper-granulocytosis can occur in the first few hours. • Repeat the CBC every 4 to 6 hours for the first 48 hours and analyse locally. • Indicate the time of sampling on each sample. As a guideline only: • Doses > 5 Gy: early and severe haematological alterations. • Doses ≥ 3 or 4 Gy: the drop in the number of lymphocytes can exceed 50% of the initial value. SEARCH FOR CHROMOSOMAL ABERRATIONS This analysis can be carried out by a laboratory specialized in this technique, as the Institute of Radiation Protection and Nuclear Safety (IRSN) in France. This the most sensitive biological dosimetry examination and the most specific for irradiation. It provides an accurate retrospective estimate of the received dose as from 0.1 Gy. • If a rapid estimation of the dose is required, particularly in case of doubt concerning the interpretation of the CBCs: take a sample in the first few hours. It takes a minimum of 72 hours to obtain the result. • In the other cases: the sample can be taken later, there is no technical urgency. The reliability of the examination remains the same whether the sample is taken on the same day or several weeks after exposure. LYMPHOCYTE ASSAY LEVEL OF IRRADIATION After 24 hours After 48 hours I Greater than 1,500/µl Greater than 1,500/µL Low (moderate damage) II Between 1,500 and 500/µl Between 1,500 and 500/µl Severe (severe damage necessitating hospitalisation) III Less than 500/µl Below 100/µL Lethal (intensive or palliative treatment, as the case may be) Essential sample taking: complete blood count (CBC) and the search for chromosomal aberrations. Analyse in priority the people likely to have received the highest level of radiation (proximity to the site of the event and clinical signs). With a person suspected of having received a significant level of radiation, it is essential to perform a blood count as early as possible. COMPLETE BLOOD COUNT (CBC) Lymphocytes are the most radiosensitive cells. The drop in the number of lymphocytes is directly proportional to the dose received. 50 MEDICAL RESPONSE IN NUCLEAR OR RADIOLOGICAL EMERGENCY
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