IMRT 2018

Gamma analysis considerations

• Local or global dose deviation can be used – Global: deviation expressed as percentage of maximum or prescribed dose – Local: deviation expressed as percentage of local dose – Global dose deviation more forgiving, especially in low-dose region • Gamma analysis fails extensively in the low-dose region, but this may not be of interest: cut-off often applied • Can be performed in 2D or 3D: slightly better pass rates with 3D • Adjustment for the linac output of the day? • Adjust spatial registration of dose distributions for best result?

06/06/2018