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Table 6.2. Biodosimetry Based On Acute Photon-Equivalent Exposures

Dose estimate Time to onset of vomiting Absolute lymphocyte count
(× 109/L)b (day)
Lymphocyte depletion ratec Number of dicentricsd
Gy %a Time (hr) 0.5 1 2 4 6 8 Rate constant Per 50 cells Per 1000 cells
0 -- -- 2.45 2.45 2.45 2.45 2.45 2.45 -- 0.05-0.1 1-2
1 19   2.30 2.16 1.90 1.48 1.15 0.89 0.126 4 88
2 35 4.63 2.16 1.90 1.48 0.89 0.54 0.33 0.252 12 234
3 54 2.62 2.03 1.68 1.15 0.54 0.25 0.12 0.378 22 439
4 72 1.74 1.90 1.48 0.89 0.33 0.12 0.044 0.504 35 703
5 86 1.27 1.79 1.31 0.69 0.20 0.06 0.020 0.63 51 1024
6 94 0.99 1.68 1.15 0.54 0.12 0.03 0.006 0.756    
7 98 0.79 1.58 1.01 0.42 0.072 0.012 0.002 0.881    
8 99 0.66 1.48 0.89 0.33 0.044 0.006 <0.001 1.01    
9 100 0.56 1.39 0.79 0.25 0.030 0.003 <0.001 1.13    
10 100 0.48 1.31 0.70 0.20 0.020 0.001 <0.001 1.26    

a Cumulative percentage of victims with vomiting.
b Normal range 1.4-3.5 × 109/L.
c The lymphocyte depletion rate is based on the model Lt = 2.45 × 109/L × e-k(D)t, in which Lt equals the lymphocyte count (× 109/L), 2.45 × 109/L equals a constant representing the consensus mean lymphocyte count in the general population, k equals the lymphocyte depletion rate constant for a specific acute photon dose, and t equals the time after exposure (days).
d Number of dicentric chromosomes in human peripheral blood lymphocytes.

Note: Depicted above are the three most useful elements of biodosimetry. The first column illustrates the percent of people who vomit, based on dose received and time to onset. The middle section reveals the time frame in which a patient develops lymphopenia. Two lymphocyte samples drawn at different times can then be used to predict a rate constant, which is then used to estimate exposure dose. The final column represents the current "gold standard," which requires several days before the result is known. We recommend initiating colony-stimulating factor if either onset of vomiting or lymphocyte depletion kinetics suggests an exposure for which treatment is recommended, which can then be discontinued if necessary when data from chromosome dicentrics are known.

Acknowledgments: The authors thank W.E. Jackson for assistance in preparation of this table. Special thanks go to Mark Behme for expert graphical assistance. This work was supported in part by the Armed Forces Radiobiology Research Institute, work number AFRRI-04-3.

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