HI-ART promises more accurate and effective radiotherapy

If all goes well, a next-generation image-guided radiotherapy system may be on the market early next year. Dubbed HI-ART (highly integrated adaptive radiotherapy system), the product uses previously scanned CT, MR, and PET images or images captured by the system itself to identify exact tumor size and guide administration of radiotherapy. Its Madison-based developer, TomoTherapy, plans to apply for marketing clearance from the FDA in the next four to six weeks.

“It’s a helical CT, but instead of a conventional x-ray tube, we use a linear accelerator,” said John Barni, TomoTherapy CEO.

To be imaged by HI-ART, patients move slowly through a precisely controlled radiation beam. The amount of radiation and shape of the beam are constantly adjusted, monitored, and verified to fit a plan optimized by the patient’s physician. The system applies a form of intensity-modulated radiation therapy (IMRT), which has been around for several years. What’s new is HI-ART’s helical approach, Barni said.

The system consists of a gantry that combines a high-dose treatment beam and CT-style dose detection. With use of a multileaf collimator, patients are irradiated in helical fashion.

“We have 360° continuous rotation of a modulated radiotherapy beam,” Barni said. “We’re delivering the radiation very similar to a spiral CT acquisition.”

In essence, the radiation oncologist is able to identify tumor contours and healthy tissue. The system establishes a plan that orchestrates the delivery of radiation by 64 beams according to instructions developed by the radiation oncologist. If the physician confirms the plan, the collimators and other parameters are then set up.

“We are building into the system the ability to automatically match the plan to the patient position at time of treatment,” Barni said. “That will give us another way to optimize the delivery process.”

The system evolved from a research program that began about 10 years ago at the University of Wisconsin in Madison. The Tomotherapy Research Group founded TomoTherapy in 1997 to commercialize their ideas.

Although multileaf collimators have been used in the past for 3-D conformal radiation therapy, their flexibility in delivering radiation has been limited, Barni said. Not so with HI-ART, which administers radiation by CT slices and can gauge exactly the dose delivered to patients.

A TomoTherapy research unit has been installed at the University of Wisconsin Comprehensive Cancer Center in Madison, and staff is currently being trained on it. Clinical work is expected to begin by October. If the company applies to the FDA as planned and reviewers act quickly, marketing could begin by the first quarter of 2002, Barni said. Eventually, he envisions delivering between 100 and 150 systems per year, or roughly 20% of the linear accelerator market.