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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.

  • verbose name: Data
  • default value: None
  • port type: DataPort
  • value type: Packet (can be None)
  • data direction: INOUT

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.

  • verbose name: Differential Pathlength Factor
  • default value: 6
  • port type: FloatPort
  • value type: float (can be None)

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.

  • verbose name: Partial Volume Correction
  • default value: 60
  • port type: FloatPort
  • value type: float (can be None)

chromophores

List of chromophores for which to estimate quantities.

  • verbose name: Chromophores
  • default value: ['HbO', 'HbR']
  • port type: SubsetPort
  • value type: list (can be None)

coords_unit

Unit of the channel positions. Typically this would be m for meters, but some data may have it wrong.

  • verbose name: Coordinates Unit
  • default value: m
  • port type: EnumPort
  • value type: str (can be None)

set_breakpoint

Set a breakpoint on this node. If this is enabled, your debugger (if one is attached) will trigger a breakpoint.

  • verbose name: Set Breakpoint (Debug Only)
  • default value: False
  • port type: BoolPort
  • value type: bool (can be None)

metadata

User-definable meta-data associated with the node. Usually reserved for technical purposes.

  • verbose name: Metadata
  • default value: {}
  • port type: DictPort
  • value type: dict (can be None)