Add ability to apply DAP calibration factors to chart data

[David Platten]

I would find it useful to be able to apply appropriate DAP calibration factors to chart data to help when comparing doses across rooms.

I think it would be less computationally expensive to apply any calibration factor to the chart data once it's been calculated by the existing code.

The DAP calibration factors wouldn't be applied to any data stored in the database.

I envisage a button below each DAP-related chart that says "Toggle DAP calibration factors" or something similar. This would toggle the application of appropriate DAP calibration factors to the data.

Any thoughts?

We could do something similar for skin dose map calculations...

[David Platten]

Simply applying a calibration factor to the chart data won’t work because the chart data may incorporate a wide date range, and the calibration factor may have changed over time.

[David Platten]

DAP calibration factors could be associated with display name entries.

DAP calibration factors may change over time, so it needs to be possible to associate multiple calibration factors with each display name entry, and be able to specify the time period over which a particular calibration factor applies.

A default calibration factor of 1.0 could be used for all systems.

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A new “calibrated DAP” database field could be created:

• the value could be calculated during import
• the values could be updated en-mass via an admin interface, or just for specific systems - this would enable calibrated values to be produced from DAP data that was already in the database
• the calibrated values could be displayed in the user-interface (summary and detailed pages) - this may be useful when using the data for individual patient dose estimates as a result of an accidental or unintended exposure
• the calibrated values could be used when producing charts
• the calibrated values could be used when creating skin dose maps

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Alternatively, calibration factors could be applied at the point that they were needed, without creating a new “calibrated DAP” database field:

• apply appropriate calibration factors in the chart functions when the initial dataframe is created (study date would become a required dataframe field so that different factors could be applied to different date ranges)
• apply the appropriate calibration factor when calculating skin dose maps

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Extend this calibration factor idea to include calibration factors for fluoroscopy system dose at reference point data (used for skin dose maps)?

• May require kVp- and filtration-specific factors

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[David Platten]

My colleague @Hannah Thurlbeck and I prefer the first suggestion, where a new “calibrated DAP” database field is created.

We think that assuming a 1.0 default calibration factor is a bad idea. If there's no calibration factor available for a system for certain time period, and that system has a large factor, say 1.3, then chart data would be misleading: if the data that doesn't have a specified calibration factor is included in a chart, the data with an unspecified calibration factor would use a default factor of 1.0, and so make the overall value in the chart wrong. If the data with unspecified factor was ignored then the chart value would reflect the correct result.

[Ed McDonagh]

So would you have an option to show only calibrated data, or only uncalibrated data? Some exposures would be plotted either way, some would disappear when you toggled to show calibrated?

[David Platten]

Yes, I think I’d have an option that shows only calibrated data, or only uncalibrated data. Maybe another checkbox on the chart options.