NIRStar 14.1 - User Manual
Page 56 of 124
Quality Scale Example
Figure 40 (left) shows one example of the quality scale results where three channels are labeled ‘lost’.
Channels labeled red (critical) or white (lost) should be re-evaluated to see if a technical problem
occurred, or whether the optode preparation should be improved.
Please note, that in this example, all lost channels share the same source (No. 5). This leaves several
possible explanations for the problem:
i) The source 5 is not placed in the correct position (i.e. too far from the detectors)
ii) There may be bad optical contact, e.g. because of hair blockage
iii) Hardware problems affect source no. 5
In this particular case, evaluating the source levels in detail revealed critically low signal level for one
wavelength only, so case iii (a damaged emitter for the second wavelength) seemed most likely to be the
cause.
Please note that NIRx recommends its customers running periodical static phantom tests in order to
make sure that the hardware is working correctly. The Quality Scale itself is not enough to evaluate it and
should be used only as a first indicator of some problem. A more in-depth evaluation of system
performance is possible with the static phantom provided with NIRx instruments.
Figure 40. Results of signal quality for a setup using an LED with one wavelength broken. Left: Signal Quality
index; Right: evaluating the signal levels for wavelength 850nm.
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