Hartford HealthCare Cancer Institute | Trilogy™ Stereotactic System

The Program  |  Treatment Options  |  Benefits  |  Patient Resources 

The Trilogy™ Stereotactic System from Varian Medical Systems at the Helen & Harry Gray Cancer Center is the first of its kind in Connecticut.

The hospital is building on its reputation as a leader in radiation oncology with this versatile new image-guided radiation therapy (IGRT) system. Trilogy’s “dynamic targeting” assures accurate beam positioning, while built-in CT (“cat scan”) diagnostic imaging pinpoints tumors with digital accuracy and positions them in the high-dose area despite any internal organ movement. Advances in low-dose, high resolution X-ray imaging, precision delivery and patient positioning are the three advantages of the Trilogy system.

In addition to image guidance, the other two components of the unique triad are intensity modulated radiation therapy and stereotactic radiation therapy. Since 2003, radiation oncologists at the Cancer Center have used intensity-modulated radiation therapy (IMRT) to “shape” a dose of radiation to match the contours of a specific tumor.

“We can superimpose thousands of small fields of radiation to sculpt the beam around a solid tumor,” says Andrew L. Salner, M.D., director of Hartford Hospital’s Cancer Program. “The prostate gland tends to move within the body, so we image the tumor before treatment every day.”

Not only is the next-generation Trilogy linear accelerator safer and more sophisticated than existing systems, it adds new options for stereotactic neurosurgical treatment. With the Trilogy system, radiation oncologists and their neurosurgical colleagues can target inoperable lesions or tumors in critical areas of the brain, using image-guided delivery and a helmet-like device that holds a patient’s head completely still during radiosurgery."

We can now deliver a precisely placed, one-shot or multi-shot, extremely high dose of radiation to a tumor in the brain,” says Dr. Salner. “The beam is so highly focused that sensitive structures like the optic nerve receive significantly less radiation.”

Even more precise than so-called “gamma knife” radiosurgery, the state of-the-art Trilogy system minimizes radiation damage to healthy tissue. Hartford Hospital’s Radiation Oncology Department also offers brachytherapy—either permanent or temporary—for prostate cancer treatment. Permanent seed implants can be implanted into the prostate gland, where they give off radiation at a low dose rate over several weeks or months.

“Temporary brachytherapy can be targeted much more precisely to spare the urethra,” explains Dr. Salner. “Tiny catheters deliver highly radioactive iridium-192 seeds to the tumor. Because the computer controls how long each seed remains in each catheter—from fractions of a second up to many seconds—we can selectively control he radiation dose to different regions of the prostate.” The hospital’s prostate cancer team individualizes care for each patient and helps to determine which option is best for each patient.

Brachytherapy is also used in the management of several other types of cancer. For example, women with localized breast cancer who meet specific criteria are candidates for MammoSite partial breast radiation, which can be completed in five treatment days instead of the usual six weeks. The technique utilizes high dose rate brachytherapy consisting of a twice daily 20-minute treatment to focus on the portion of the breast at risk.

Radiation oncologists are now collaborating with medical oncologists/hematologists to bring new approaches to cancer treatment. Hartford Hospital is pioneering a radioactive cancer breakthrough called radioimmunotherapy. To deliver a dose of radiation to a tumor target, radiotherapy drugs hitch a ride on a monoclonal antibody —a protein designed to lock onto a specific area on a cell’s surface.

Once they acquire their molecular target, yttrium-90 or iodine-131 radioisotopes blast the cancer cell with a lethal dose of radioactivity. The FDA has approved two radioactive drugs, Zevalin and Bexxar, for patients with relapsed or recurrent Non-Hodgkin’s lymphoma who have failed chemotherapy.

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Treatment Options

The Trilogy™ Stereotactic System
Trilogy™ Stereotactic System from Varian Medical Systems is the most advanced, sophisticated machine of its type in the world.

As the leading image-guided radiotherapy (IGRT) system, Trilogy marks the beginning of a new generation of cancer care. The versatile Trilogy system combines imaging and treatment technologies, and can be used to deliver the widest range of external beam radiotherapies: 3D conformal radiotherapy, IMRT, stereotactic radiosurgery, fractionated stereotactic radiation therapy and intensity-modulated radiosurgery for cancer and neurosurgical treatments.

Advanced imaging capabilities built into the system allow therapists to position patients for treatment with submillimeter accuracy. A respiratory gating system compensates for any tumor movement that occurs as a patient breathes.

The Trilogy system is powerful, and it can deliver radiotherapy doses at least 60 percent faster than conventional accelerators. This shortens the length of time patients need to spend undergoing treatment. In addition, the radiation beam is highly precise, allowing clinicians to deliver treatments with unprecedented accuracy.

How it Works
The Trilogy system is built around an advanced medical linear accelerator, a machine that rotates 360 degrees around the patient to deliver radiotherapy treatments from many angles. The Trilogy accelerator has been enhanced for stereotactic applications that involve delivering higher doses of radiation to smaller areas over a shorter period of time.

The Trilogy system incorporates sophisticated technologies for shaping the radiation beam so that the dose of radiation is limited to the region of abnormality. By changing the beam shape over time while delivering the radiation, doctors achieve very fine control over how, and where, the radiation is administered.

The Trilogy Stereotactic System also incorporates a number of technologies for positioning patients accurately, including:

  • A special X-ray imager that is used to check the patient's position prior to treatment and to monitor the position of the targeted area during treatment.
  • An optical guidance system with infrared cameras that continuously monitor the patient's position to provide therapists with real-time feedback about any changes in a patient's position.
  • A "respiratory gating" technology that coordinates treatment with respiration, to compensate for tumor motion due to the patient's breathing.

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Benefits

Patient Benefits
Through more precise targeting of the beam, radiotherapy can be more effective at treating disease while simultaneously reducing side effects of the treatment. Due to the increased accuracy and power, smaller lesions can be treated more quickly, easily and effectively.

State-of-the-art motion management techniques allow doctors to coordinate treatment with a patient's breathing patterns. During these treatments, patients can continue to breathe naturally, reducing stress and increasing comfort.

Radiotherapy can be used to treat more different types of cancer, which means that more patients can be spared the invasive techniques of surgery and/or chemotherapy.

Physician Benefits
The Trilogy Stereotactic System is the first linear accelerator that can deliver all advanced forms of external-beam radiation therapy. By allowing doctors to choose the most appropriate treatment modality for treating cancer—whether in the body or the brain—Trilogy makes it possible to provide the most appropriate therapy for a specific patient's case, rather than being limited by technology.

With Trilogy, doctors have the option to treat small lesions using stereotactic radiosurgery, which is delivered in a single treatment; or stereotactic radiotherapy, which is delivered over a few days; as well as more traditional forms of radiotherapy.

The Trilogy system includes technology for positioning the patient exactly, using images of the tumor and surrounding anatomy taken just prior to each treatment. The images are used to verify tumor position immediately before the radiation beam is switched on. This gives clinicians the ability to maximize the dose to the tumor, and minimize the dose to surrounding healthy tissue.

The respiratory gating system automatically turns the beam off and on to compensate for breathing motion during treatment. This keeps the radiation beam focused on the tumor, and further protects normal healthy tissues.

The Trilogy system and its accessories can shape a beam very precisely, with sub-millimeter accuracy. In addition to the precision of its beam, Trilogy offers the highest dose rates available, to deliver a potent punch of radiation in a short amount of time. This combination of precision and power allows Trilogy to reduce both treatment times and side effects.

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Patient Resources

Rounds Wellness Magazine, Summer 2006

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