So what is proton therapy, anyway? It’s a superfancy cancer treatment that specifically targets diseased tissue with a beam of protons. 

Sounds pretty awesome. It is, in theory. Standard radiation treatment exposes healthy tissue to high levels of dangerous radiation, but with proton therapy’s precision, it’s possible to go after tricky-to-treat cancers that strike the brain, spine, and eyes without damaging anything else in the vicinity. 

Wait, you said it’s awesome “in theory.” Well, for one thing it’s pricey. Insurance usually covers the treatment, but a nine-week round of proton therapy can still cost patients twice as much as radiation. And critics say it isn’t proven to be any more effective in treating common cancers like prostate.

Is it new? Yes and no. The first dedicated proton therapy center was built in 1990, in Southern California. But we’ve been smashing atoms since 1929, and Harvard doctors started using a cyclotron in the 1960s to treat spine and eye tumors.  

If it’s that precise, at least the treatment center must be pretty small. Uh, no. The facility is 58,000 square feet—roughly the size of a football field. 

 

 

The beating heart of a proton facility is its cyclotron, a giant hockey-puck-shaped particle accelerator that splits hydrogen atoms and propels protonsat 223 million miles per hour (60 percent of the speed of light). 

Magnets channel those protons from the cyclotron through 100 yards of piping and into one of three types of treatment rooms. 

 

 

 

The gantry, which looks like a CT scan machine—only much bigger—is a tube that fully encircles and revolves around the patient to target hard-to-reach diseased tissue. (Treats breast, skin, and gastrointestinal cancers.)

 

The inclined beam, which could eventually replace the massive gantry, delivers protons from two angles: horizontal to the tumor, and at a 60-degree inclined angle. (Treats gynecological, digestive, and thorax cancers.)

The fixed-beam device does not move; instead patients sit in front of it while an operator aims the beam at localized tumors. (Treats brain, eye, and prostate cancers.)  

Are the doctors and nurses protected
from radiation exposure? Yes, by:

 Minimum 6-foot-thick walls around
treatment rooms

• Minimum 12-foot-thick walls and roof
around cyclotron 

  

 

Published: July 2013

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