Welcome to Brainstuff from how Stuff Works dot com where smart Happens. I am Marshall Brain with today's question, what is proton therapy and how does it work? Imagine that you were to be diagnosed with something like breast cancer, brain cancer, or prostate cancer. Up until now, your options have been fairly limited and fairly uncomfortable. The most common first line of attack is surgery. A surgeon cuts out
the tumor as best he or she can. In the case of breast, brain, and prostate cancer, this approach can be fairly problematic. In the case of breast cancer, a woman may lose one or both of her breasts. In the case of brain cancer, parts of the brain can be damaged in the process of getting to the tumor, or the tumor may not be accessible at all. In prostate cancer, the patient is often left incontinent and impotent. In surgery is usually followed by chemotherapy to kill any
remaining cancer cells. Chemotherapy is a drug cocktail that is in essence poison. The poison kills the cancer cells by targeting cells that reproduce rapidly. The side effect is that other cells in the body that happen to reproduce rapidly like hair follicles, and the cells lining the stomach often suffer as well. This explains the hair loss and nausea that often accompanies chemotherapy. Another possibility is X ray therapy, where multiple beams of X rays penetrate the body and
intersect at the tumor. The tumor receives a high enough dose of X rays to damage the cancerous DNA and kill the cancer cells, but there can be collateral damage at the places where the X ray beams enter the body and overshoot the tumor. Healthy tissue near a tumor
often gets damaged as well. There are other therapies, including bits of radioactive serial commonly called seeds, embedded in and around the tumor in the hope of killing the tumor with nuclear radiation, various new and experimental drugs targeting things like tumor blood supply, and so on. Most of the techniques in use today have side effects that can be quite unfortunate for the patient. This is why so many
people are getting excited about proton therapy. The idea here is to use protons, which have been accelerated to near light speed in a particle accelerator to kill cancer tumors. The advantage of proton therapy is a good success rate with a low incidence of side effects. So what is a proton? If you think of a hydrogen atom, the proton is the some atomic particle at the core of the atom. A normal hydrogen atom has an electron orbiting
that proton. By stripping off the electron and leaving behind a bare hydrogen nucleus, you have a proton that can be used for proton therapy. Protons are so small that they can fly through the body doing very little damage, but they do slow down as they make their way through tissue. Eventually, the protons come to a stop. Add or near the stopping point, protons strip electrons off of
nearby atoms, changing important molecules in the process. If a doctor delivers enough protons to a tumor, cells inside the tumor die because of this electron activity. Some doctors described protons as acting like a firecracker, avoiding damage to tissue surrounding the tumor, but exploding inside the tumor. The reason is that protons do damage when they come to rest, So if they come to rest inside the tumor. The tumor is the only thing to get significant damage from
the protons. The depth that the protons penetrate into the body can be controlled by their speed. Compared to X ray therapy, there is no exit dose that can harm healthy tissue beyond the tumor, and there's only a very small entry dose. The two big problems with proton therapy right now are the fact that it is so new and the cost. There are only a handful of proton therapy facilities in the United States at the moment, and these facilities are incredibly expensive, costing hundreds of millions of
dollars to build. The cost is coming from the need for a complete, highly sophisticated particle accelerator at each facility. The particle accelerator creates the protons and then accelerates them to the precise speed needed to reach the tumor. Another problem is the high number of visits. A typical prostate cancer tumor might require forty daily visits to a proton therapy facility over the course of two months, unless you happen to live in the rare city that has a facility.
This means a long daily commute or a two month hotel stay along with the cost of the forty sessions, which can rise into the pends of thousands of dollars. The hope is that technological advances will lower the cost of new facilities, making the treatment much more accessible and less expensive. If that happens, it could open a new era in cancer treatment. For more on this and thousands of other topics, doesn't how stuff works dot com and don't forget to check out the brain stuff blog on
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