CHAPTER 8

STOCHASTIC Random “all or nothing” linear,nonthreshold playing the lottery

Deterministic Effect AKA nonstochastic or certainty effect Nonlinear threshold curve threshold assumed increases with severity of dose

Dose Linear Curves (PG 112 in Sherer, Pg.498-499 Bushong) Linear, non-threshold Linear threshold Nonlinear (Curvilinear, Sigmoid) Threshold curve Non-linear, non threshold curve Linear Quadratic Non threshold

AGE The age of the biological structure determines sensitivity Bergonie and Tribondeau Embryo-fetus-newborn-young child Decreases in late teens Stabilizes until old age increases in old age

RECOVERY Cell can recover if sufficient time is given between irradiation some cells have greater capacity for repair Sufficient radiation causes atrophy

REVIEW PRINCIPLES OF RADIOBIOLOGY ARE BUILT ON THE FOLLOWING: 1)RANDOM NATURE 2)RADIATION INTERACTS AT CELLULAR LEVEL 3)FACTORS THAT ALTER THESE INTERACTIONS