You learn something new every day

I haven't talked much lately about my progress or status of Glioblastoma Multiforme (brain tumor) they removed from my head last year, and as time goes on, I suppose I'll be talking even less, but today I had my latest MRI. The results showed no change, which is great. That means that as far as anyone can see (and it's been about 18 months or so since this whole thing began, and two months since the termination of any treatment) there has been no growth or detectable difference in my status. Of course this is fantastic news, and my doctors couldn't be more pleased.

But I learned something today. The MRI tech, Karl (big guy, nice as they come), had a few minutes before his next appointment, so we talked about a few things... drag racing, kids, and the MRI system. They do the MRI with and without contrast, to get a better look at what's going on. To give added contrast to the image, they inject a fluid with has magnetic properties. I never knew what it was, but Karl told me the stuff is called Gadolinium... Number 64 on the Periodic Table. Being the curious techie sort that I am, I looked it up. I recommend that you do the same, but in short, here's what I learned.

Gadolinium is used in nuclear marine propulsion systems as a burnable poison. The gadolinium slows the initial reaction rate, but as it decays other neutron poisons accumulate, allowing for long-running cores. Gadolinium is also used as a secondary, emergency shut-down measure in some nuclear reactors, particularly of the CANDU type. The CANDU reactor is a pressurized heavy water reactor developed initially in the late 1950s and 1960s.

Gadolinium also possesses unusual metallurgic properties, with as little as 1% of gadolinium improving the workability and resistance of iron, chromium and related alloys to high temperatures and oxidation.

Because of their paramagnetic properties, solutions of organic gadolinium complexes and gadolinium compounds are used as intravenous radiocontrast agents to enhance images in medical magnetic resonance imaging. Magnevist is the most widespread example.

Besides MRI, gadolinium (Gd) is also used in other imaging. In X-ray, gadolinium is contained in the phosphor layer suspending in a polymer matrix at the detector. Terbium-doped gadolinium oxysulfide (Gd2O2S: Tb) at the phosphor layer is to convert the X-rays releasing from the source into light. Gd can emit at 540nm (green light spectrum = 520 – 570nm), which is very useful for enhancing the imaging quality of the X-ray that are exposed to the photographic film.

A "nm" is nanometer for those of you who were wondering. A nanometer is a unit of spatial measurement that is 10-9 meter, or one billionth of a meter. It is commonly used in nanotechnology, the building of extremely small machines.

Anyway, beside Gd's spectrum range, the compound also has a K-edge at 50 kiloelectron volt (keV), which means its absorption of X-ray through photoelectric interactions is great. The energy conversion of Gd is up to 20%, which means, one-fifth of the X-ray striking on the phosphor layer can be converted into light photons.

I found it interesting anyway, but then I've got the stuff floating around in my system for a while. This accounts for my magnetic personality, er uh, well maybe.