User manual

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Click on the icon to choose the type of gamma map
select between Gamma relative error, Gamma
Normalized or Gamma Angle.
Click on the icon and from the menu select whether
the required tolerance value is set relative to the maximum dose in the plan, relative to
the plan value for the pixel in question or relative to a user-defined value. From the
menu also select whether the seach will continue to evaluate DTA out to the radius
specified by the distance criterion used for the gamma test, or whether the search is
stopped at the radius at which a gamma value ≤1 is detected. The threshold dose can
be displayed either as % of the maximum dose in the
treatment plan or as an absolute dose value in a
selection of dose units. Click on the icon to toggle
between % dose and absolute dose.
By default the gamma test is calculated as “Gamma
relative error” with 3% dose tolerance relative to maximum dose at a distance criterion
of 3mm and with the search to the entire 3mm radius. The default dose threshold is
zero, so evaluation is done for all pixels. Note: As film is usually scanned at ≥72 dpi, or
more, the spatial resolution of the Dose Map is almost always much greater than the
Treatment Plan. This means there are >1 measured pixels for every plan pixel. To
prevent gross overestimation of the gamma passing rate the plan pixels and measured
dose map must be put on the same basis for evaluation and comparison. That is the
measured dose map must be projected to the grid of the plan. To do this FilmQA
Pro
generates a Projection Map, i.e. the measured dose map is recalculated by averaging
individual pixels values grouped to reproduce the spatial resolution of the plan.