Where the cucves become congruent, aC the curve, each cell has recelved a summation of eneryzy censtties then it is clear Che uppec high-expesurs fart larzse number of hits. from these multiple hies that even though the if one tie “cell in size, and smaller. There {s . then no reason to eviluate separatel: the each discrete Hit. It is adequate, high-expesure regions, practical purposes, tne vartunce of cose™, tre rein «fll tecome for practical ceasons, the mean dose. the cell dose anc ftdentical. Staller cisx foe siuply to «use Ta other words, in tnrese the organ dose ace, for sal Then, and most iaportantly, one cana characterize and predict the probability of 2 biological response cell population, or in the organ itself, the absorbed dose D to Che organ. However, splits as one goes low2r in exposure, even though in the in terms of a singie parameter, {it is seen into independent components, Zz and Rue value of Z, the indiviaual “lets constituting that “dose” vary ywreatly the summed energy density as calls the variance is that the exocsure note that tne expectation large, remains constant, so treet the only cellular parameter that can increase with increasizg exposure ts the Ry or the number of hit sizes dose the per exposed cell. Thus, «ith &LE to cells and oryvans alike can iner2ase because of multiple hits, and one variable, However, D, with LLE, ae increases; Note it ec {is adequate neither . fs oly that while LLB has predict a dose tye the anuaber only a small fraction of exposure, the to to fan of the response cells 1. < calls dosed its counterpart aor na in tne aw ixic cin the indiviczal. reaa dose we : tirease in sacro accicents, and inat the exposed pooulation is hit with increasinz there is 20 analogue, with macro accidents, of HLZ exposure. reasoas for this ts accident rate that, for practical and ethical reasons, if other hand, w= The the in given population increases above a very srall fractisn per year, even drastic action is likely to be taken. With radiation, the accident rate can be increased at will, course of minutes, seconds, or less. It {s only because of this which may permit interactions between the hits, seen only with high-level exposure of cells 15 on the so tnat any 6 given cell can readily be exposed to dozens or more severe accideats, Sooub . ia tre ‘fact, that the “quadratic” term, to ionizing radiation, exists.