September 18, 2008

CPAC Highlights Its Proton Therapy Program at ESTRO Annual Meeting

Compact Particle Acceleration Corporation (CPAC) today announced that it introduced its state-of-the-art compact proton therapy program, featuring a dielectric-wall accelerator (DWA), during the European Society for Therapeutic Radiology and Oncology (ESTRO) annual meeting that concluded today in Gothenburg, Sweden. The proton system is currently being co-developed by CPAC and TomoTherapy Incorporated (NASDAQ: TOMO), maker of the Hi-Art(R) treatment system for advanced radiation therapy, and was featured in the TomoTherapy booth at ESTRO.

John Hughes, CPAC Vice President of Commercial Operations, led several of the presentations. Said Hughes, "We were overwhelmed by the interest and positive response we received for CPAC during the ESTRO annual meeting. Clearly, proton therapy is recognized as a promising treatment modality with the potential to deliver significant benefit for some cancer patients. Our approach has the potential to bring this technology into the medical mainstream."

High cost and large facility requirements are current barriers to proton technology entering the medical mainstream for cancer treatment. Perfecting the DWA technology for eventual use in compact proton systems could greatly reduce the cost and space needed for this type of treatment. In fact, it is intended that the DWA will be mounted on a gantry much like TomoTherapy's Hi-Art treatment system.

DWA technology was originally created as part of defense-related research at Lawrence Livermore National Laboratory (LLNL).

Physicist George Caporaso, LLNL's lead investigator on the collaboration with CPAC and TomoTherapy, gave a popular presentation at the ESTRO Presidential Symposium entitled, "A Compact Linac For Intensity Modulated Proton Therapy Based On A Dielectric Wall Accelerator."

Caporaso explained, "Our researchers have demonstrated the ability to produce protons from an extremely compact source about the size of a dime. We believe that we are making important progress toward the development of this DWA source for eventual cancer therapy applications."

CPAC will attend the American Society for Therapeutic Radiology and Oncology (ASTRO) Annual Meeting in Boston, Mass., Sept. 21-25, 2008, joining TomoTherapy in booth 1533. Rock Mackie, Ph.D., TomoTherapy co-founder and chairman of the board, will deliver a series of proton therapy-related presentations. For exact times of Dr. Mackie's talks, visit the ASTRO overview page at

In addition, Hughes will be leading a CPAC presentation during the TomoTherapy Analyst and Investor Presentation on Sept. 22.

About Compact Particle Acceleration Corporation (CPAC)

CPAC is a recently formed company focused on the development of the dielectric-wall accelerator (DWA) and its application to particle therapy and other fields of use. DWA technology is expected to form the basis of a compact, high-gradient particle accelerator that is anticipated to be used in medical, security and defense applications.

About TomoTherapy Incorporated

TomoTherapy Incorporated has developed, markets and sells the TomoTherapy(R) Hi-Art(R) treatment system, an advanced radiation therapy system for the treatment of a wide variety of cancers. The Hi-Art treatment system combines integrated CT imaging with conformal radiation therapy to deliver sophisticated radiation treatments with speed and precision while reducing radiation exposure to surrounding healthy tissue. The company's stock is traded on the NASDAQ Global Select Market under the symbol TOMO. To learn more about TomoTherapy, please visit

Forward-Looking Statement

Statements in this release regarding future business, plans, events, expectations, products and other similar matters, including but not limited to statements using the terms "will", "look forward to", "intended", "anticipated", constitute forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements contained in this press release are subject to risks and uncertainties that could cause actual results to differ materially from those anticipated, including but not limited to risks inherent in the development and commercialization of new technology and products, and the other risks listed from time to time in TomoTherapy's filings with the U.S. Securities and Exchange Commission, which by this reference are incorporated herein. These forward-looking statements represent TomoTherapy's judgments as of the date of this press release. TomoTherapy assumes no obligation to update or revise the forward-looking statements in this release because of new information, future events or otherwise.

(C)2008 TomoTherapy Incorporated. All rights reserved. CPAC logo, TomoTherapy, the TomoTherapy logo and Hi-Art are among trademarks, service marks or registered trademarks of TomoTherapy Incorporated.