Commonwealth Cancer Center is pleased to offer their patients the benefits of a 23IX Linear Accelerator system from Varian Medical Systems.  This treatment machine is one of the most advanced and sophisticated of its type in the world.

As the leading image- guided radiotherapy system (IGRT), the 23 IX marks the beginning of a new generation of cancer care. The versatile 23 IX combines imaging and treatment technologies, and can be used to deliver the widest range of external beam radiotherapies: 3D conformal radiotherapy, IMRT, and IGRT.

Advanced imaging capabilities built into the system allow the radiation therapist to position patients for treatment with sub-millimeter accuracy. Due to this increased accuracy and power of this system, lesions can be treated more accurately and effectively. Dose levels can be increased and target volumes (the three-dimensional areas to receive treatment) can be reduced--so tumors get a higher dose of radiation and healthy surrounding tissues get very little. Higher doses have been shown to enhance treatment effectiveness. And better targeting reduces the possible side effects of radiotherapy.

Because of this, Commonwealth Cancer Center has chosen the 23 IX system as the choice to offer to their patients.

Commonwealth Cancer has chosen to offer the Varian 23 IX System because of the wide range of patient benefits it offers. Among them are:

Varian Medical Systems’ On-Board Imager accessory is designed to improve the precision and effectiveness of cancer treatments by giving doctors the ability to target and track tumors more accurately. The On-Board Imager, an automated system for image-guided radiation therapy (IGRT), will enable clinicians to obtain high-resolution X-ray images to pinpoint tumor sites, adjust patient positioning when necessary, and complete a treatment, all within the standard treatment time slot.

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.


Image-guided radiotherapy (IGRT) refers to the use of sophisticated imaging technologies to guide the delivery of precise forms of radiation therapy. Tumors can move during treatment (usually do to patient respiration) and between treatments (usually due to day-to-day variations in patient setup). Dynamic Targeting IGRT from Varian Medical Systems offers clinicians advanced imaging techniques to verify patient position and tumor position at the time of treatment. Knowing exactly where the tumor is allows clinicians to reduce the volume of tissue irradiated, targeting only the tumor and sparing the surrounding normal tissue. Irradiating less normal tissue reduces the toxicity of radiotherapy, improving the patient’s quality of life, and may make it possible to deliver higher radiation doses to the tumor and hereby increase the likelihood of local tumor control.


When patients are positioned on a treatment couch, an X-ray system mounted on a robotic arm is rotated around the body, to gather images that pinpoint a tumor’s exact location. These images are then compared with existing images (MRI, CT or other kinds of scans) in order to determine if the tumor has moved since the last treatment. Because tissues and organs can settle around bones differently each time a patient lies down on a treatment table, tumors can end up in different positions from one treatment session to another. In addition, tumors can move several centimeters due to a patient’s normal respiratory cycle.

For Dynamic Targeting IGRT, the medical linear accelerator, or treatment machine, is outfitted with a number of sophisticated imaging devices that provide the clinician with images that help to guide the treatment. Central to this approach is Varian’s On-Board Imager® kV imaging system, an imaging tool that is attached to the treatment machine on a pair of robotic arms, and produces low-dose, high-resolution kilovoltage X-ray images for pinpointing the position of the tumor immediately prior to treatment. The On-Board Imager can be operated in three distinct imaging modes to generate different types of images, including:

  • Radiographic (two-dimensional)
  • Fluoroscopic (moving, in real-time)

  • These distinct images types provide doctors with different information about the tumor and surrounding anatomy, revealing changes in tumor shape, size or position over a multi-week course of treatment. Fluoroscopic images can be used to track tumor motion for a clear indication of exactly how a tumor will move during treatment due to respiration or other normal physiological processes. This enables doctors to design optimal treatments for their patients. A system for delivering Dynamic Targeting IGRT also comprises additional tools—an electronic portal imaging device and a respiratory gating system—to enable clinicians to verify patient positioning and to synchronize treatment with the tumor motion caused by respiration.

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