UF Proton Therapy Institute - Interesting Factoids

Florida Proton was built from the ground up as a radiation treatment center. They are primarily a proton center, but also provide state of the art treatment with conventional radiation as well.

This is a diagram of the treatment equipment. I'll try to get some closer pictures of it, but if you click on the picture, you'll get an enlarged view that is easier to see.

Notice at the top left, the Cyclotron. That's where the protons are "harvested", (my word...). The protons are Hydrogen protons which are harvested by splitting molecules of water.

The water molecule (H2O) is split into its component atoms to give 2 hydrogen and 1 oxygen atom. The oxygen is discarded and I'm guessing a couple of them get together to form an oxygen molecule (O2). Where that goes, I'm not sure.

Coming back to the hydrogen, now we have these two hydrogen atoms, each with one proton and one electron. Now its time to split the protons off from their electrons. As I understand it, all of this splitting is done by shooting very high levels of electricity, (235 million volts), at the molecules and atoms. (One of the things I'm not clear on is if that happens inside the cyclotron. I'll find out and correct this if not.) In any case, the atom is split into its one proton and one electron and they 'discard' the electron by simply running it to ground. (Imagine the size of THAT grounding spike!!)

Once the hydrogen protons have been separated, the cyclotron accelerates them to 62% of the speed of light. (Yikes!!) That is the speed required for the protons to travel through human tissue to a depth of 13 to 15 inches. It happens through a series of specialized magnets within the cyclotron. At this point, billions of protons line up and are fired down the line that you see coming out of the cyclotron toward the treatment gantries.

Factoid: The cyclotron weighs appx. 200 metric tons! (a metric ton is appx. 2200 lbs.) All of the equipment was built by IBA or Ion Beam Applications in Belgium and had to be shipped here. Because it is so heavy, the cyclotron had to be welded to the bottom of the ship's hold. If the ship had gotten into rough seas and the cyclotron shifted, it might have capsized the ship! Once it arrived in Jacksonville, the available cranes were not able to lift it from the hold and some kind of super-crane had to be brought in to do the job!

Once it got here, they installed it and then built the building around it. Because it is in Florida, they were not able to put it below ground as is usual. Normally the centers are built 40 feet below ground so that the earth is used as a radiation shield. Instead of that, they had to build this place with concrete walls eighteen and a half feet thick! AND, since the normal aggregate that they use in concrete here is relatively porous, they had to import granite aggregate from up North. Using the more porous aggregate would have allowed radiation leaks!

I mentioned above that they use 235 million volts to harvest the protons. All of this and also the transmission of the protons down the line causes a great deal of heat which must be managed. For that, they have many many water lines that course through the whole mess. Bottom line? They use LOTS of both electricity and water! The bill for each commodity is over $50,000 a month! (and I thought ours was bad!)

The three large circular things you see to the right of the cyclotron are the treatment gantries. The beam is turned and directed down the line by a series of magnets. Since the proton is a positively charged particle, they used positively charged magnets. The two repel each other so by careful placement of the magnets, they are able to direct the protons wherever they want them. (That is horribly oversimplified, but it was about as much as I could understand! LOL!)

Factoid: The gantries were brought in in pieces and assembled right where they sit. Each gantry is over 40 feet in diameter and weighs 110 metric tons! They are so well balanced that a person could turn one with bare hands. They are moved by two 1.5 horsepower electric motors.

So now the proton beam is at the back of the gantry. If you look back at the picture and look at Gantry #1, you see that it is rotated so that the "nozzle" is coming down from the top. (If I were on the table, I'd be looking up at the nozzle.) That monster that runs over the top of the gantry to the nozzle is the path that the beam takes. The thing you see at the very top houses an 8,000 pound bending magnet which finally gets the beam to the right place!

Factoid: The final turn to get the beam into the nozzle is done via an 8,000 pound bending magnet.

Now the beam is at the nozzle and this is where my therapists take control of it. (Up to now, Ion Beam Applications has had it.) By this time I would have been rotated around so that I was lying on the table head-first into the gantry. On the picture, Gantry #3 has been rotated into the treatment position and we would be treating through my right hip on that day.

I have to thank God that there are people out there who are so much smarter than I and who can conceptualize something like this, get it built, and then run it so successfully.

I am utterly in awe.