Radiobiology 5

Question 1

Is the linear quadratic model suitable ?

Answer 1

• Shows that rate of kill increases with increasing dose due to increased lethal rather than sub-lethal damage
• Assumes, initial slope is proportional to the dose, and the curving region is proportional to D^2.
• No curve would show a level of zero capacity for repair

Question 2

What do high values mean in the LQ model?

Answer 2

• high values of alpha = indicate a greater radiation sensitivity
• high beta values = greater repair capability

Question 3

What is the alpha/beta ratio mean?

Answer 3

• units are Gy
• dose at which linear and quadratic components are equal
• when ratio is small - good repair
• when ratio is large - poor repair