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Posted By: jonF Bili soft output tester - 06/09/18 3:15 PM
Hi
Can anyone please advise what phototherapy tester to use with this device, we have bili compacts and currently use the BIO TEC 74345, but the bili soft is a little confusing, as the bio tech meausrement reads different to what it says on the bili soft matts ?????, am i looking to deep into this...? what is the output for these devics in micro watts/cm2

Jon
Posted By: Geoff Hannis Re: Bili soft output tester - 06/09/18 4:47 PM

Phototherapy has moved on a bit since "my day" - no more special (blue) fluorescent lamps; but now we have LED light sources feeding mats, pads or "tubes" via fibre-optic cables. However, the physics of the end result remains the same:- so many micro-watts per square centimeter (should really be watts per square meter, surely?) at specific wavelength ("spectral range" in nm - typically 450 nm) at a noted distance.

Originally Posted by jonF

Can anyone please advise what phototherapy tester to use with this device


Light Meter 2?

Originally Posted by jonF

what is the output for these devics in micro watts/cm2


See the specs.

If I were you I would carry on using the Bio-Tek. Just always take your readings at the same distance from the pad (one foot, 300 mm, or whatever gives "results of comfort"), and be consistent in recording the results. smile

Out of interest, what does the labelling on the pads actually say?
Posted By: jonF Re: Bili soft output tester - 06/09/18 5:35 PM
on the pad it reads
Small pad irradiance is 35 µW·cm-2·nm-1
Large pad irradiance is 50 µW·cm-2·nm-1

when you use the bio tec meter your readings can be 1434 micro watts/cm2, so is there a conversion factor to get the results
Posted By: jonF Re: Bili soft output tester - 06/09/18 5:37 PM
on the pad it reads
Small pad irradiance is 35 µW·cm-2·nm-1
Large pad irradiance is 50 µW·cm-2·nm-1
Posted By: Geoff Hannis Re: Bili soft output tester - 06/09/18 5:45 PM

What do you read with the Bio-Tek 1 meter (100 cm) from the pad? think
Posted By: jonF Re: Bili soft output tester - 06/09/18 6:07 PM
will check when back in the office tomorrow
Posted By: jonF Re: Bili soft output tester - 07/09/18 10:40 AM
we test with reading at a disatnce of 40cm, and the output can read anything from 1600 - 1800 micro watts/cm2
Posted By: Geoff Hannis Re: Bili soft output tester - 07/09/18 11:10 AM

Why 40 cm ... that's not how the equipment is actually used. 40 cm would have been a valid distance in the days of traditional overhead phototherapy lamps.

To satisfy my own curiosity ... what does the Bio-Tek meter give at 100 cm; and (or) at what distance do you get readings in the 35 or 50 range? think

Meanwhile, I notice that the Olympic Model 22 Bili-Meter has a special sensor for testing fibreoptic pads; one that sits directly on the pad. My take on all this is that (unlike the old fluorescent blue lamps) output on these new LED units should not deteriorate over time, and what we are more concerned about is uniformity of output across the mat or pad.

Now I'm wondering what you would get if you covered the pad with a piece of cardboard with just a 1 x 1 cm square cut out of it (then took readings at various positions to test for uniformity by moving the cut-out around the pad). smile

As you have already suggested, a "conversion factor" shall need to be applied when using the test equipment you have to hand. My own suggestion is that all we are looking for here is little more than an "is the equipment working, and giving blue light output in an acceptable range" question. I was thinking about something along the lines of applying the "inverse square law" to arrive at readings of comfort. At 100 cm I would have hoped to see something like 1100 (for the 35 pad) and 1580 (for the 50 pad). I was working towards a "fiddle factor" of 31.6 (being the square root of 1000), but your 40 cm readings seem to have blown that idea out of the water! So now I'm guessing that the Bio-Tek meter is being saturated by blue light from the pad (maybe the active area of the pad needs to be factored in) in a way that light scattered from a fluorescent tube would not. All this could be total BS, of course (see the "Bluffer's Guide to Biomedical Engineering")!
Posted By: Geoff Hannis Re: Bili soft output tester - 07/09/18 7:47 PM

More research on this issue:- Vreman. smile
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