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

REVIEWPRINCIPLES OF RADIOBIOLOGY ARE BUILT

ON THE FOLLOWING:

1)RANDOM NATURE2)RADIATION INTERACTS AT CELLULAR LEVEL

3)FACTORS THAT ALTER THESE INTERACTIONS