When you are battling cancer it’s important to use the most effective therapy against your tumor(s). Radiation therapy is used to kill cancer cells and shrink your tumors. Radiation damages cells making it impossible for these cells to continue to grow and divide. Although radiation does damage cancer and normal cells, most normal cells can recover from the effects of radiation and function properly. The goal is to damage as many of your cancer cells as possible and limit harm to your healthy tissue.
Depending on your situation, the goal of radiation treatment is the complete destruction of an entire tumor. Or your doctor could aim to shrink a tumor and relieve your symptoms. Radiation therapy may be used alone or in combination with other cancer treatments, such as chemotherapy or surgery. In some cases, you may receive more than one type of radiation therapy.
Prophylactic Radiation Therapy
Prophylactic radiation therapy is a term you may hear your doctor mention. This is radiation that may be given to areas that do not have evidence of cancer. This is done to prevent cancer cells from growing in the area receiving the radiation.
Palliative Radiation Therapy
Palliative radiation therapy also may be given to help reduce symptoms such as pain from cancer that has spread to the bones or other parts of the body.
Radiation Therapy treats cancers of:
Soft tissue sarcomas
Doses depend on the type of cancer you are diagnosed with and whether there are tissues and organs nearby that may be damaged by radiation.
Intensity Modulated Radiation Therapy (IMRT) is a type of 3-dimensional radiation therapy that uses computer-generated images to show the size and shape of the tumor. Thin beams of radiation of different intensities are aimed at the tumor from many angles. This type of radiation therapy reduces the damage to healthy tissue near the tumor.
Divides each treatment field into multiple segments (up to 500 per angle)
Allows dose escalation to most aggressive tumor cells; best protection of healthy tissue
Modulates radiation intensity, gives distinct dose to each segment
Uses multiple beam angles, thousands of segments
Requires inverse treatment planning software to calculate dose distribution
HIGH PRECISION RADIATION THERAPY
As the trend to higher doses, smaller number of fractions, and tighter margins becomes an important part of radiotherapy, better verifiable localization is a necessity. Image-guided localization provides this type of real-time high-precision localization. Based on implanted gold markers or anatomic landmarks, and electronic portal imaging, computed radiography, or standard port films - provides precise couch moves to achieve target alignment.
In some situations, image-guided localization is best achieved by utilizing implanted markers which your doctor may refer to as fiducials. Implanted markers are broken into two main categories - bone and soft tissue.
Markers are imperative in all situations where the target moves with respect to external marks (e.g. tatoos). Certainly prostate, liver and other such internal organs can be much more accurately targeted using implanted markers. In cases where the target moves in an identical fashion with respect to the adjacent bony anatomy it is possible to utilize the bony anatomy as the registration points.
RAPIDARC™ RADIOTHERAPY TECHNOLOGY
RapidArc™ radiotherapy technology from Varian Medical Systems is a new approach to image-guided, intensity-modulated radiation therapy (IG-IMRT) that delivers precise treatments in shorter times than conventional IMRT.
RapidArc represents a major medical advance and is more comfortable for patients because they spend less time in their daily treatments. A fast, precise RapidArc treatment takes less than two minutes. Patients can be in and out of treatment quickly and return to their daily routine.
RapidArc rotates 360 degrees around the patient, enabling the very small beams with varying intensity to be aimed at the tumor from multiple angles. Unlike helical IMRT treatments or other forms of radiation therapy, with RapidArc the radiation treatment being delivered to the patient can be modulated continuously throughout treatment. This means that higher doses of radiation are delivered to hit the tumor harder, and less radiation is delivered to surrounding healthy tissue.
RapidArc treatments are delivered using either a Clinac® or a Trilogy® linear accelerator from Varian Medical Systems outfitted with imaging capabilities. The RapidArc imaging capabilities let the clinician see the location of the tumor in three dimensions before treatment. If the cancer has moved due to physical changes, treatment can be adjusted so the patient receives a precise treatment. This treatment platform is the most widely used and reliable platform available. Over 75 percent of the leading U.S. hospitals and clinics use Varian technology.* *Data based on the 2006 edition of “America’s Best Hospitals” from U.S. News & World Report.
How It Works
RapidArc™ radiotherapy technology from Varian Medical Systems delivers treatments using either a Clinac® or a Trilogy® linear accelerator, outfitted with an On-Board Imager® kV imaging system for using images to guide patient placement and treatment delivery. The linear accelerator rotates around the patient to deliver radiation treatments from nearly any angle. During a RapidArc treatment, radiation is shaped and reshaped as it is delivered continuously from virtually every angle in a 360-degree revolution around the patient.
Like other forms of radiation therapy, RapidArc treatments are planned using sophisticated computer programs that analyze diagnostic image data and calculate the best way of delivering the radiation dose to minimize impact on healthy tissues for each patient.
Immediately prior to treatment, the exact location, size, and shape of the patient’s tumor is visually observed through a simple two-minute imaging procedure using the machine’s On-Board Imager.
After imaging is completed, the images are reviewed by the therapist and the patient’s position can be adjusted so that an accurate treatment can be delivered. The patient does not need to move off the treatment couch for this process—all adjustments are made automatically by the treatment couch.
A RapidArc radiotherapy treatment is delivered quickly—in less than two minutes and with just one turn of the machine around the patient. RapidArc shapes and modulates a highly focused treatment beam so that it targets the tumor precisely, sparing surrounding healthy tissues. It treats the entire tumor with pinpoint accuracy and is easier on the patient, who does not have to hold still for long periods of time.
During a RapidArc treatment, the treatment beam is continually shaped by a multileaf collimator (MLC), a device with 120 computer-controlled mechanical “leaves” or “fingers” that move to create apertures of different shapes and sizes.
RapidArc™ radiotherapy technology from Varian Medical Systems represents a new revolution in cancer care. RapidArc enables your clinician to treat some types of cancer with great precision in less than two minutes.
RapidArc is delivered with a medical linear accelerator, which is a large machine that generates high-powered X-rays and rotates around you as you lie on a treatment couch, delivering the beams from many angles. With RapidArc, the entire treatment is completed with a single rotation of the machine.
RapidArc is a new approach to delivering image-guided, intensity-modulated radiation therapy (IG-IMRT). Image guidance improves tumor targeting, and IMRT shapes the radiation dose so that it conforms closely to the three-dimensional shape of the tumor. That means more radiation is delivered to the tumor and less to surrounding healthy tissues.
The treatments are fast. That makes it easier on you—you don’t have to hold still for long, and you’re in and out in a matter of minutes each day. With RapidArc, IMRT treatments that typically require at least 10 minutes can be completed in less than 2 minutes.
A RapidArc radiotherapy system incorporates technology that makes it possible for your treatment team to position you for treatment with sub-millimeter accuracy. An On-Board Imager® kV imaging system mounted on the treatment machine provides high-resolution X-ray images of the targeted area just before each daily treatment.