Decay of Technetium 99m or living with a science nerd (my poor Wife!!!)

[99tito99]

Well this will be an example of my extreme science-nerdy nature.

Last year my wife was being evaluated for a shoulder replacement surgery. On her x-ray the Doctor saw some ‘funny-business’ (my words not his) and order a bone scan (to jump ahead no serious funny-business was found).

For the bone scan she was injected with 20.9 mCi (5.6 nanograms) of Technetium (99mTc) medronic acid which her body need to metabolize for 24 hours prior to the actual scan.

Technetium-99m is a metastable nuclear isomer of technetium-99 which decays to technetium-99 with a half-life of 6.01 hours releasing 140.5 (98.6%) and 142.6 (1.4%) keV gamma rays.

After her injection my Geiger counter (Homemade and not particularly sensitive; LND-712) could detect her five feet away and would scream next to her skin (unfortunately it is not calibrated).

So, here is the nerdy part and maybe a bit too much information; I had her collect her urine which was very active.

I attached my Geiger counter to my PC sound card and using Ludlum’s RadCalcLE software I started counting away on the sample (on the urine that is).

I made two counting runs: one for 12 hours and after adjusting the set up to get a higher count rate a second run for 24 hours.

The results are attached in the pdf. The exponential decay equation yielded half-lives of 6.4 and 6.3 hours respectively for the two runs. I would say not too bad for a jerry-rigged, non-calibrated setup.

Cheers,
Mark
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[George Dowell]

You have discovered Urninium, chemical symbol PU.

http://www.qsl.net/k/k0ff/Measuring%20PU/PU.jpg

George Dowell

[Steven Sesselmann]

Mark,

That's always been the problem with the "hot chicks" they don't stay hot forever, but a half life of only 6 hours is ridiculous!

While on the subject, did you look for a 140.5 Kev Gamma ?

Steven

[Rich Feldman]

Thanks for sharing the image and data, Mark. Did your wife notice any measures taken by the clinic to reduce irradiation or contamination of their workers?

Reminds me of an opportunity I could have exploited better, long ago. In 1996 my cat was "hot" for a while, when his hyperthyroidism was treated with a dose of iodine 131. The procedure was relatively novel at the time, and the cat lived for another six years.

He stayed at the clinic for almost a week, while too radioactive to be allowed home. Then B.C. and his excretions had to be sequestered indoors for a month. The rules are much less strict for human patients. Apparently the veterinary oncology industry now has facilities more appealing to pet owners, and safer for the staff: http://www.avmi.net/newfiles/Hyperthyroidism/iCat4.html

With a compact Geiger counter, I measured the cat's activity decreasing at the biological rate (3 or 4 day half life), while the used cat litter activity built up to a peak before approaching an 8 day decay curve.

First B.C. had a technetium scan to locate and size his thyroid glands, and to help determine the radioiodine dosage. (Image below is of some other cat). The imaging table included a lead collimator with many small, parallel holes through its thickness, as in: http://www.avmi.net/newfiles/Scintigrap ... aphy3.html
I wonder what compound of 99m Tc is used to mark the thyroid (and salivary?) glands. Plain iodide would, AFAIK, concentrate independently of whatever cation it came with.

[Richard Hull]

It is not nerdy here to collect technicium loaded urine from loved ones or self to experiment with during the short period it is useful.

Ily, (bionerd), on you tube has done it. I have also collected it from the old gal when she had a test performed. I'm sure a lot of rad freaks have done this, but haven't "fessed" up to it. The most hazardous part of the experiment if you not doing the peeing is asking the wife to give you her pee.

Richard Hull

[George Dowell]

A good way to log these short half life metastable isotopes is to use the MultiChannel Scaler function of your MCA.

George Dowell


http://www.qsl.net/k/k0ff/Generating%20 ... ome%20Lab/