Proton radiation treatment can target solid tumors with less harm to surrounding tissue than X-ray radiation therapy.
Pretreatment planning requires a 3D map of “proton stopping power,” or how fast the proton loses energy and slows down as it passes through tissues before hitting the tumor. Those values are now estimated from images taken by X-ray computed tomography (CT) scanners, but a proton CT (pCT) scanner would make direct and more accurate measurements.
Now, UC Santa Cruz researchers, working with Loma Linda University Medical Center scientists, have a prototype pCT capable of completing a full scan of a human head-sized object in less than 10 minutes, said Robert Johnson, chair of the Physics Department and first author on a paper describing the machine, published in IEEE Transactions on Nuclear Science.
Making a scan in a few minutes requires measuring a million individual protons per second, noted Johnson. With experience designing NASA’s Fermi–Gamma ray Space Telescope—plus leftover silicon-strip detectors from that project—Johnson helped overcome those technical challenges.
“We are now comparing simulated treatment plans [with the prototype] against those obtained by a new X-ray technique,” said Johnson. “If we’re successful it could really improve cancer treatments, which is the ultimate goal.”