Picket Fence: Skipped Leaf Pair Label?

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1

Hello,

I’ve been adapting the pylinac Picket Fence module into some of our analysis scripts but noticed that for our HDMLC unit that one of the leaves is being skipped when I was plotting the max errors for each leaf (see picket_fence_max_offsets.PNG). Looking at the normal pylinac analysis plot, there didn’t seem to be any obvious gaps in the leaf analysis. I was looking through the picket fence documentation and code for any clues but haven’t come up with anything. I thought I’d compare the picket’s leaf numbers and center positions to the center positions in the picket settings just to double check whether a leaf was being skipped for some reason but the centers appear to match even though one of the leaf pair labels is skipped: [14,107].

I haven’t seen this behaviour with our Millennium 120 MLC units. Any ideas what might be happening?

Thanks!
Brandon

picket_fence_max_offsets.PNG
picket_fence_max_offsets.PNG910×911 22.7 KB

analysis_results_plot.jpg
analysis_results_plot.jpg1920×1040 223 KB

compare_picket_leaf_nums_to_settings_leaf_centers.png
compare_picket_leaf_nums_to_settings_leaf_centers.png514×918 17.1 KB

2

Hey Brandon, unsure why it would skip a leaf, but often it’s a matter of noise. Have you tried applying a filter first? As mentioned on github, the MLC handling will change in v2.5, moving from an empirical detection process to a configurable a priori MLC configuration which should deprecate problems like these.

3

Hi James,

I tried a fairly wide range of filters but none seemed to label any of the leaf pairs with [14,107]. I’ll check in with v2.5 to see if that resolves this!

Cheers,
Brandon