Physicists receive patent for improved cancer ther...(ailability. How it works The idea ...),Health

How it works

The idea behind radiation therapy is to deliver a lethal dose of radiation to cancerous cells. In conventional x-ray radiation therapy, many healthy surrounding cells are also exposed to the radiation because x-ray beams deposit their energy as they travel through tissue. In fact, most of the dose of x-rays is deposited near the surface of the body. Though cancerous cells tend to be more susceptible to the damaging effects of radiation (or less able to repair it), the collateral damage to healthy tissues limits the dose physicians can use to destroy the tumor.

Proton therapy offers an advance over conventional x-rays because proton beams deposit most of their energy where the beam stops. The original proton therapy synchrotrons were designed to deliver cell-killing doses of radiation to tumors in three dimensions by aiming proton beams from multiple directions to stop at the depth of the tumor tissue. That precision targeting allows doctors to deliver higher doses to the tumor cells while sparing healthy surrounding tissue.

But accelerators are often costly to build and difficult to maintain, explaining why the design principles for hospital-based accelerators must be radically modified, and why relatively few hospitals have them. The new accelerator design developed by the Brookhaven team offers two main advantages: "rapid cycling" and "strong focusing."

Rapid cycling allows proton beams to be injected and extracted from the synchrotron in just one turn around the circular particle accelerator. Unlike the earlier machines, which required multiple turns, this eliminates the need for sensitive feedback systems to control the beam currents.

"This makes the machine more robust and reliable to operate. It's more of a turn-key operation," Peggs said. "Turn it on and it consistently starts up like a transformer, rather than booting up like a PC."

Strong focusing refers to the ability
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