Mismatch of posion of maximum values in Gamma analysis
Quote from phuong on September 4, 2025, 8:36 amI’m comparing PDD files in the software and noticed a slight mismatch in the reported dmax positions.
For the measured PDD file, dmax is at z = 1.41 cm, but in the curve window it shows 1.38 cm.
In my simulated PDD file, dmax is at 1.50 cm, but the curve window shows 1.49 cm.
Why does this discrepancy occur, and is there a way to correct it to improve the accuracy of the gamma index calculation?
Thank you for your help!
I’m comparing PDD files in the software and noticed a slight mismatch in the reported dmax positions.
-
For the measured PDD file, dmax is at z = 1.41 cm, but in the curve window it shows 1.38 cm.
-
In my simulated PDD file, dmax is at 1.50 cm, but the curve window shows 1.49 cm.
Why does this discrepancy occur, and is there a way to correct it to improve the accuracy of the gamma index calculation?
Thank you for your help!
Quote from milrocas on September 16, 2025, 1:58 pmDose profiles need to be interpolated to match the same spatial resolution, therefore small discrepancies (0.1 mm in your case) can be found between the original profile and the interpolated one. Those interpolations do not degrade the accuracy of gamma analysis.
Dose profiles need to be interpolated to match the same spatial resolution, therefore small discrepancies (0.1 mm in your case) can be found between the original profile and the interpolated one. Those interpolations do not degrade the accuracy of gamma analysis.
Quote from AmeliaThomas on August 26, 2026, 10:49 pmThat slight shift usually happens because the software applies spline interpolation or grid resampling when rendering the display curve, which can nudge the peak dmax point off your raw dataset value. To fix this and clean up your gamma index calculation, try resampling both files onto the exact same spatial grid resolution before running the analysis, and check if automatic smoothing filters are altering your peak during import, though whenever I get stuck staring at data curves trying to hunt down a tiny 1mm discrepancy like this, taking a quick break with my ske crystal pods is pretty much essential to reset my eyes before diving back into the settings.
That slight shift usually happens because the software applies spline interpolation or grid resampling when rendering the display curve, which can nudge the peak dmax point off your raw dataset value. To fix this and clean up your gamma index calculation, try resampling both files onto the exact same spatial grid resolution before running the analysis, and check if automatic smoothing filters are altering your peak during import, though whenever I get stuck staring at data curves trying to hunt down a tiny 1mm discrepancy like this, taking a quick break with my ske crystal pods is pretty much essential to reset my eyes before diving back into the settings.