PALO ALTO, Calif., - June 17, 2002 - Varian Medical Systems, Inc. (NYSE: VAR)today announced it has received 510(k) clearance from the U.S. Food and Drug Administration (FDA) to market a rapid new version of its inverse treatment planning software for SmartBeam® IMRT. The new Helios® 6.5 runs on the company's Eclipse® platform, introduced last year to expedite and improve the quality of radiation treatment planning in a Windows environment. It will be exhibited at the American Association of Physicists in Medicine (AAPM) meeting in Montreal, July 14-18, 2002. "This new version of Helios brings all of the power, speed, and industry leading features of our Eclipse platform to the inverse treatment planning process for IMRT," said Tim Guertin, president of Varian Medical Systems' oncology business. "Now three-dimensional conformal radiation therapy, brachytherapy, and IMRT can all be planned on the same workstation." Helios 6.5 is an inverse treatment planning tool that calculates an optimal way of filling a radiation oncologist's prescription specifying the radiation dose levels for a tumor and dose constraints for the surrounding healthy tissues. Helios on the Eclipse platform incorporates several new features and enhancements that improve the speed and accuracy of IMRT treatment planning. The software maintains its easy-to-learn, user-friendly graphical interface. It automates a number of complex functions, including organ contouring and segmentation, which help doctors work with three-dimensional diagnostic images to create prescriptions for radiation treatment. Helios incorporates a smart template library of dose-volume constraints for clinical cases that routinely require inverse treatment planning. Doctors can add customized templates to the library as they are developed. Interactive Optimizing Helios performs millions of calculations to optimally fulfill the radiation dose prescription accurately and in the shortest possible amount of time. With Helios 6.5, users can freely change any parameter while the optimization is taking place, making adjustments to the plan "on the fly." "Helios displays the results of the optimization as it progresses in real time. Users can modify the dose-volume constraints and immediately observe the impact on the dose-volume histogram," said Corey Zankowski, PhD, treatment planning product manager. "Without the interactive user-interface, the physician would have to wait until the entire optimization process was finished before evaluating the results. That takes a lot of time. With Helios, since many dose-volume combinations can be evaluated in a single optimization session, you can do a better job clinically in less time." Helios 6.5 incorporates a very fast optimization algorithm. The program can optimize a nine-field head and neck IMRT plan in less than 20 minutes a task that can take many hours with other kinds of inverse treatment planning systems. Helios can plan for the treatment of multiple targets simultaneously, or the delivery of high and low dose in separate regions of a single tumor as easily as it plans for a single uniform target. Flexible Interfaces and Full Integration The new version of Helios provides a comprehensive set of verification and quality assurance tools for verifying dose distributions, as well as tools for commissioning an entire IMRT system. The program also incorporates an open architecture capable of exchanging information with other radiotherapy devices. Helios is now fully integrated with Varian's Vision™ product line, so that patient plan data is shared with XimaVision (for simulation), VARiS 6.5 (for treatment), and PortalVision (for treatment verification). As an integral part of the Eclipse platform, Helios offers users all of the powerful Eclipse planning tools for inverse planning tasks. Helios and Eclipse provide a common user interface, making it easier to learn how to operate the system. IMRT and Inverse Treatment Planning IMRT is an advanced form of cancer radiotherapy that deliver high radiation doses directly to tumors while sparing more of the surrounding healthy tissue. The number of cancer centers offering SmartBeam IMRT from Varian Medical Systems more than doubled to 100 in 2001, and has since grown to 140 worldwide. With IMRT, doctors specify the desired radiation doses for tumors as well as the exposure constraints for surrounding healthy tissues and organs. Inverse treatment planning software determines the optimal way to modulate the radiation beam's intensity during a treatment by working backward through a complex range of radiation delivery options. It then produces the electronic instructions that guide the treatment equipment. Varian Medical Systems will begin shipping the new Helios 6.5 in late July, 2002. For more information, call 800-544-4636 or 650 424-5700 or visit www.varian.com.