FIGURE 90.12 Effect of whole-body radiation on lymphocytes in the first days after exposure Estimating the whole-body radiation dose may be difficult, especially when complicated by injuries that are not due to radiation The signs and symptoms during the prodromal period are quite nonspecific except for a rapidly decreasing lymphocyte count Nausea and vomiting are sensitive but nonspecific symptoms Patients who not have nausea and vomiting are unlikely to have been exposed to a radiation dose that is large enough to cause acute radiation syndrome However, individuals may have nausea and vomiting for reasons other than exposure to radiation The whole-body radiation dose from radiation accidents is rarely uniform The nonuniform nature of the radiation dose makes it more difficult to predict the biologic effects from the exposure Chromosome analysis (cytogenetic dosimetry) may be helpful in estimating the radiation dose, but the results may not be available for about week The second type of radiation exposure that can occur is local exposure, which involves a radiation dose to a small part of the body Large doses can be tolerated if only a small part of the body is exposed Local radiation injuries may cause bone marrow depression if accompanied by a significant whole-body radiation