Current State of Proton Computed Tomography

Radiation therapy is currently used to treat over half of the 1.5 million diagnosed cancer patients in the U.S each year. In the past 2 decades, proton beam therapy has been used successfully in many of these patients. Currently, over 100,000 patients have been treated worldwide with 100 to 250 MeV proton beams in 30 proton treatment centers. The success of all radiation therapy and particularly proton therapy depends critically on good 3D imaging to localize the tumor in the body. To date, X-ray CT and MRI are the principle modalities for imaging in radiation treatment planning. However, using X-ray CT introduces inherent limitations on the ability to predict where the dose is delivered. To overcome these limitations, 3D CT imaging using protons was first proposed by Allan Cormak, 1979 Nobel Laureate for X-ray CT. In this talk, the motivation and current state of development of proton CT will be discussed.