Technetium-99m cardiac imaging (Eagar's personal case)

Even technetium (no terrestrial stable isotope) has a structural-adjacent industrial use. Tom's own stress test at Mount Auburn Hospital. Used to introduce the structural-vs-functional materials dichotomy.

This is a very general kind of wrap-up lecture. I've shown you the periodic table before. What elements do I use for structural materials? I use almost all the elements on the periodic table for something. Even technetium, which doesn't exist on earth — not as a structural material, but I do use it in radiology for people getting stress tests in a hospital, even though it's only got a half-life of ten hours. They make it, they fly it in Learjets around the country, and when I had a stress test at Mount Auburn Hospital, they shot me full of technetium, and I was radiating fast enough they could take pictures of my heart pumping while I was running on a treadmill. How exciting. And they learned I'm out of shape.

Personal medical anecdote (stress test, prostate cancer follow-up, sinus infection — all at Mount Auburn Hospital, radiologist Dr. Abner an MIT physics alum). Used to set up the case below and to illustrate that technetium has practical use despite a 10.5-hour half-life.

But we actually use technetium. I've had people inject technetium in me. If you ever, later in your life, have to go undergo a stress test — they make you run on a treadmill, monitor everything, take live X-rays, then inject you with technetium, and take new live X-rays. They image different things, because technetium is decomposing so fast that they can use the technetium itself for the radiograph. They can actually see where the fluid is going in your heart.

I want your own analysis. We want to know what you think. This is something of interest to you, and you ought to have an opinion. If you don't have an opinion, form one by doing the study. For the elements, you could talk about how the element was discovered, the economics of the element, the externalities — which we'll talk about in my lecture tomorrow. These are other factors that come into play for different materials. Availability and extraction, uses, recycling. You could go to the US Geological Survey website — they already have the whole outline done for you, for about 70% of the elements. You want to look up technetium? They'll have an article on technetium. Won't be very long. Anybody know why technetium is not very long? Yeah, it's unstable. It has about a 10-hour half-life. It doesn't exist on earth except in nuclear reactors.

Used to illustrate why Pourbaix calculated thermodynamic stability for technetium despite its terrestrial absence. Develops into the autoradiographic stress-test procedure and the supernova-nucleosynthesis aside about iron's stability.

If you look at the table of contents, they've got H2O, hydrogen peroxide, hydrogen, lithium, sodium, potassium, rubidium, cesium — he's going down the periodic table. Second column: beryllium and magnesium, calcium. He groups them like the periodic table, and he's calculated everything. He even calculated Tc. What's Tc? It's technetium. Doesn't exist on this earth in a natural form, although you nuclear guys know that we use it for stress tests. The reason it doesn't exist on this earth is the elements were formed in supernovas, when stars blow up. You take the hydrogen and the helium and they make heavier elements. The most stable element in the periodic table is something called iron. That's why there's a lot of iron in the universe.