A question for those with IR transmission filters.

[Doug]

I'd like to hear from people with IR transmission filters re the following.
I am looking for a way of showing the position of my arm arteries (very deep).
Recently I have had a TKR op and managed some blood clots on/in the lungs.
I have to have a blood test every few days to check INR, but many of the blood suckers can't find the pipe lines and I have already had 2 arterial spasms (they hurt, mega big time:sad:). So if IR will show the location of my arteries, I will quickly order a filter.
cheers,
Doug

[Suzy_A]

Hi Doug,

its not quite that simple....

Firstly you need a camera that is senstative to IR...

Assuming you have a digital still camera, the actual sensors of the camera is very sensative to IR, but the camera manufacturer will have put an IR blocking filter in front of the sensor that blocks the IR and so the camera is normally only sensitive to visible light. Having said that, some IR does get through, but not much...

I had a Canon 30D. Using a visible light blocking filter which lets through IR - a Hoya R72 - I needed about a 10 second exposure at f4 in full sun with the camea at 800 ASA to get a decent image. After I had the camera's internal IR blocking filter removed, I could then do a similar shot in 'normal' time - eg at 100 ASA, at 1/1000 sec at f4. But to take 'normal' visible light photos, I had to have a IR blocking filter over the lens to re-compensate.

My 30D was stolen, so now my new unmodified 40D is back to long exposures for IR.

However there have been a few cameras made that had easily user-removable IR blocking filters. I think a few of the Sonys had these.

The other possibility is with a digital video cameras. Many of these are quite sensitive to IR, and simply illuminating the area with IR (eg from IR LEDs) in the dark will provide you with an IR image. If you want to do this in the 'light', then you'll need a R72 filter or similar over the lens.

I have a Sony video camera and it works very well with IR - it even has a 'night' mode in which a IR LED lights up and you get a good monochrome image in total darkness.

As for seeing your arteries and veins.... well, you skin is a bit more transparent at IR wavelengths, but you would still be lucky and need a lot of experimentation to be able to see much. Most of the photos of people that I have taken with IR don't show much in the way of arteries etc.

What you probably need is a specialist ... bloodsucker. Can't remember what they are called. I work in a hospital and if we have problems, we page a nurse that has special training and skills in jabbing folk with a syringe. He has his own office, wears what he wants and wanders around quoting Aunty Jack.

The other option is to use ultrasound or fluoroscopy and contrast to find the arteries.

I hope this helps!

[Lee]

You obviously need a better blood collector! I think the problems noted above will get in your way of success - ultrasound would be a better idea, do you have a spare $10k :D
A lot of GP practices now carry machines to analyse your INR on a fingerprick specimen of blood - might be worth looking for....

[Doug]

Thanks Susan. I have an SBIG ST10mxe imager which is very sensitive to IR. It does not use an IR blocking filter as various colour filters are used to make up a colour composite image. These filters are chosen to have good IR rejection in them selves.
Sorry to hear about the theft of your 30D, I hope it was not pinched by a fellow astro-imager.
As for the fluoroscopy, that sounds a bit involved.
1 week down the track and my arm still is sensitive to shock etc. It is certainly a weird sensation to lightly stroke my arm just below the elbow and feel a sort of duplicate feeling around the wrist!
cheers,
Doug

[Doug]

Thanks Lee, no, no spare 10K. Apparently my GP service does not have these pin prickers, so I guess I'll just have to hope that in the future I can get a competent blood sucker............I wonder if someone could train a mosquito?
cheers,
Doug

[Suzy_A]

Just try taking an image of your arm with your camera in the dark and with no filters, but lit up with an IR source - use a few IR LEDs, or even a TV remote control.

[Doug]

Thanks for your reply Susan, What I had in mind was detecting the IR from the warm blood flowing through the veins.
cheers,
Doug

[Doug]

Lee, it seems that most doctors do not use these INR meters because Medicare will not cover the cost. Hospitals often do because they are funded differently. I will just have to put up with the risk and avoid the particular person that seems less adept than most.
cheers,
Doug

[Suzy_A]

Your talking about long-wave IR - in that case, you need a thermal imager - have a look at http://www.maxmax.com/aXNiteThermal_TIR1.htm This is a really cheap one that only costs $10,000, but they have a better camera for $27,000.