EstimateConcentrations¶
Estimate chromophore concentrations (HbO, HbR) from delta-optical density (OD) at multiple wavelengths.
This uses the modified Beer-Lambert Law (MBLL) which relies on the fact that the different chromophores have different light absorption spectra. This calculation depends on a number of parameters, notably the differential pathlength factor and the partial volume correction, both of which can be set as parameters of this node. The value ranges to use can be looked up from textbooks. Incorrect assumptions will mostly result in incorrect scaling of the estimated concentrations (or their changes). Version 0.9.0
Ports/Properties¶
data¶
Data to process.
dpf¶
Differential Pathlength Factor (DPF). This is a factor, often between 4-9, which relates optical pathlength through some tissue (e.g., bone, skin, brain) to the distance between optodes.
pvc¶
Partial Volume Correction (PVC). A correction term that quantifies what fraction of the optical path is subject to concentration changes -- for fNIRS this is typically on the other of 40-90. The DPF is divided by the PVC to yield the Partial Pathlength Factor (PPF), which is often loosely around 0.1.
chromophores¶
List of chromophores for which to estimate quantities.
coords_unit¶
Unit of the channel positions. Typically this would be m for meters, but some data may have it wrong.
set_breakpoint¶
Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.
metadata¶
User-definable meta-data associated with the node. Usually reserved for technical purposes.