Varian Medical Systems, Inc., a Palo Alto, California company, has announced that two of its On-Board Imager™ devices for 3D Image Guided Radiation Therapy (IGRT) have been installed at the new University College Hospital in the UK. Another such device has been installed at the Humanitas Clinic in Milan, the first for Italy. On-Board Imager™ is an accessory medgadget for the Clinac® and Trilogy™ medical linear accelerators (covered earlier), and is designed to improve “the precision and effectiveness of cancer treatments by giving doctors the ability to target and track tumors more accurately,” according to the company.
Here’s an explanation on how the combined system, tanked up with robotic technology, functions:
Up to now, radiation oncologists have had to contend with variations in patient positioning and with respiratory motion by treating a margin of healthy tissue around the tumor. IGRT enables doctors to locate the tumor while the patient is in the treatment position, and to minimize the volume of healthy tissue exposed to radiation during treatment.
Varian’s On-Board Imager is mounted on the treatment machine via robotically controlled arms which operate along three axes of motion, so that they can be positioned optimally for the best possible view of the tumor.
An amorphous silicon flat-panel X-ray image detector yields digital images showing internal anatomic landmarks with a high degree of precision. In addition, the image detector can track anatomic motion and thus provide doctors with a clear indication of exactly how a tumor will move during treatment due to respiration or other normal physiological processes. Varian has also incorporated a unique 150 kV X-ray tube designed for generating precise, high-resolution CT-quality images from a moving gantry.
By using the robotic technology and control software to position the On-Board Imager and patient couch, the total system offers the automation, speed, and flexibility needed to make the IGRT process clinically practical for thousands of cancer patients. The system is designed for full integration with Varian’s VARiS Vision™ image and information management system as well as the company’s Eclipse™ treatment planning software products.
Varian’s Clinac and Trilogy accelerators, equipped with the new On-Board Imager, will give doctors the best of two critical technologies for image-guided radiation therapy. It combines two important technologies on one platform-low-dose, high resolution, kilovoltage X-ray imaging and integrated software control of all treatment parameters. This opens the door to improved, rapid, cost-effective automated treatments that are conducive to patient comfort.
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