IMRT 2018

Data analysis: gamma index

A gamma analysis compares each calculated value to all measured values, both in terms of dose deviation and DTA.

r m = point in measured distribution r c = point in caculated distribution r(r m ,r c )= distance between r m and r c δ (r m ,r c )= dose deviation in r m to r c Δd m = DTA criterion ΔD m = dose deviation criterion

For each r

, the r

c with the lowest gamma value is identified.

m

All r

m with γ ≤ 1 have passed the combined gamma criterion. The percentage of acceptable γ -values can be used as an overall agreement measure.

06/06/2018