Medical Device Daily

Among the biggest challenges of treating prostate cancer is that the organ tends to move significantly in mere seconds during treatment. Accuray (Sunnyvale, California) hopes its latest product, the InTempo adaptive imaging system, will help radiologists overcome that challenge. The imaging device is designed to enhance the CyberKnife robotic radiosurgery system's ability to track and correct for motion of the prostate during treatment. The InTempo is being showcased this week at the American Society for Therapeutic Radiology & Oncology (ASTRO) annual meeting in Boston.

"The InTempo system is like an artificial intelligence that calculates where the prostate is," CEO Euan Thomson told Medical Device Daily Friday as he boarded a plane to Boston for the ASTRO meeting. "The more it sees it moving, the faster the pictures are taken, automatically correcting the robot."

By increasing imaging frequency during periods of rapid and erratic prostate movement, the CyberKnife system tailors treatment delivery uniquely to the movements of the prostate throughout the treatment session, according to Accuray. This continual assessment of prostate motion combined with the CyberKnife's automatic correction for movement in real time, not only helps to ensure prescribed doses are delivered to the prostate, it also helps to ensure surrounding sensitive structures are maximally spared, the company said.

With conventional radiation delivery techniques, such as 3-D conformal and arcing IMRT, large treatment margins are commonly used to ensure adequate dose coverage in the event a potential prostate shift occurs. According to Accuray, this additional dose coverage often encompasses regions of the rectum, bladder, and urethra, increasing the risks of related toxicities and complications.

"Motion of the prostate during treatment has long been recognized as one of the major limiting factors for prostate dose escalation. This motion requires continual monitoring throughout treatment, which only the CyberKnife system can provide," said Eric Lindquist, senior VP and chief marketing officer at Accuray. "The InTempo system takes the treatment of prostate cancer to an entirely new level, giving clinicians added confidence when delivering high-dose, hypofractionated radiation."

With robotic technology, the CyberKnife uses continual image guidance to automatically track, detect, and correct for intra-fraction motion throughout the treatment, Accuray said.

During most treatment of this sort, Thomson said, the clinician has to rely on pictures taken of the prostate before the treatment – sometimes five minutes or more. Because of this, the company says conventional radiation delivery systems often fail to recognize prostate movements that occur during treatment delivery, "potentially resulting in considerable degradation of overall targeting accuracy."

The addition of InTempo to Accuray's CyberKnife comes at a time when treating prostate cancer is somewhat controversial with a lot of doctors recommending the "wait and see" approach. Last month a group urged against prostate screening in older men, saying that there is more harm than benefit from the screening and treatment based on a positive diagnosis. The U.S. Preventative Services Task Force found that treatment based on routine screening causes "moderate-to-substantial" harm to men of all ages, such as erectile dysfunction, urinary incontinence, bowl dysfunction, and death. These harms are especially important, the task force noted, because some men who are treated for prostate cancer would never have developed symptoms during their lifetime (Medical Device Daily, Aug. 6, 2008).

In addition to "watchful waiting" and radiation therapy, other management strategies for localized prostate cancer include active surveillance (periodic biochemical monitoring with conversion to curative treatment if disease progresses), radical prostatectomy, and brachytherapy (or radioactive seed implantation therapy).

Thomson told MDD that the reason Accuray is releasing the InTempo now is because the company has seen "such an incredible change in prostate patients using this technique" and that "we're 100% about trying to refine it."

The CyberKnife system was first cleared by FDA in 1999 for head and neck tumors. In 2001, the company received FDA clearance to expand the use of the system to anywhere in the body when radiation treatment is indicated (MDD, Oct. 3, 2001).

Accuray says the CyberKnife extends the benefits of radiosurgery to include extracranial tumors, including those in the spine, lung, prostate, liver and pancreas. To date, the CyberKnife has been used to treat more than 50,000 patients worldwide and currently more than 140 systems have been installed in hospitals in the Americas, Europe and Asia, the company noted.

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