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FAQs: RapidArc

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What is RapidArc?

RapidArcTM radiotherapy technology is a new form of intensity-modulated radiation therapy (IMRT). IMRT shapes the radiation dose so that it conforms closely to the three-dimensional shape of the tumor. This means more dose to the tumor, and less to surrounding healthy tissue. RapidArc quickly delivers a complete IMRT treatment with as little as a single rotation of the treatment machine around the patient. The entire tumor volume receives the radiation dose during the revolution of the machine.

To administer a RapidArc treatment, physicians use computer-generated images to plan and then deliver tightly focused radiation beams to cancerous tumors. Using RapidArc technology, our physicians can deliver a precise radiation dose that conforms to the shape of the tumor, while limiting the amount of radiation that reaches surrounding healthy tissues. Another benefit provided by RapidArc is the speed of a treatment which in many cases takes less than two minutes.

Why would I want to be treated with RapidArc?

RapidArc is an extremely fast and precise form of radiation therapy. It allows clinicians to quickly and accurately deliver dose to cancer cells while keeping the dose to surrounding tissues as low as possible.

Faster treatments are not only more comfortable, but can be more accurate as well. Since a patient will have to spend less time holding still, it will be easier to avoid movements that could compromise the accuracy of the treatment. RapidArc delivers treatments two to eight times faster than other forms of radiotherapy.

What kind of radiation is used in RapidArc?

Photons (X-rays) are used to deliver RapidArc. The radiation is generated by a machine called a medical linear accelerator. While using RapidArc, the linear accelerator can produce very small beams with varying intensities can be aimed at a tumor from multiple angles to attack the target in a complete three-dimensional manner. In fact, RapidArc can be delivered with beams the size of 2.5 x 5-millimeter pixels the size of a pencil tip each with varying intensity. The idea is to deliver the lowest dose possible to the surrounding healthy tissue, while still delivering the maximum dose to the tumor.

What happens when a person is treated with RapidArc?

Patients receive RapidArc treatments according to various schedules, usually five days a week for six or seven weeks. During a RapidArc treatment, the linear accelerator rotates around the patient to deliver the radiation from nearly every angle. The radiation is shaped and reshaped as it is continuously delivered from virtually every angle in a 360-degree revolution around the patient. Treatment consisting of a 360-degree revolution takes less than two minutes.

What is the RapidArc treatment process like?

Most cases require a treatment preparation session. Special molded devices that help the patient maintain the same position every day are sometimes developed at this point. Colored, semi-permanent ink is often used to mark the patient's skin, to assist in aligning the radiation equipment with the target area. The entire process (including CT scan) takes approximately 20 minutes to an hour to complete. Following the CT scan, the RapidArc planning process usually takes several days.

The first RapidArc treatment session is sometimes longer than subsequent ones so that additional X-rays and checks can be done. A typical RapidArc treatment lasts less than 2 minutes. In the treatment room, the therapists use the marks on the patient's skin to locate the treatment area. The patient is then positioned on a treatment table. Sometimes, special molded devices are used to help with immobilization to assure correct positioning. The radiation therapist will also use the On-Board Imager kV imaging system (OBI), an X-ray imager that is mounted on the treatment machine to position patients for sub-millimeter accurate treatment. The therapist will use the OBI to produce high-resolution X-rays of the targeted area before the daily treatment is delivered; making sure the patient is in the optimal position before administering the treatment. The radiation therapist leaves the treatment room before the machine is turned on. The machine rotates around the patient to deliver the radiation beams, which are shaped by a special attachment called a multileaf collimator, a device with 120 computer-controlled mechanical "leaves" or "fingers" that can move to create apertures of different shapes and sizes. The therapist will leave the treatment room. When the treatment begins, patients do not see the radiation. If a patient becomes uncomfortable, however, the machine can be stopped at any time.

How long is a course of RapidArc treatment?

Treatments vary depending on your diagnosis, ask your physician for information about your specific diagnosis. Generally, radiation therapy usually is given five days a week for six or seven weeks. When radiation is used to alleviate pain or other symptoms, the course of treatment lasts for two to three weeks. For each radiation therapy session, the patient is in the treatment room for about 10 minutes. These types of schedules, which use small amounts of daily radiation rather than a few large doses, help protect normal body tissues in the treatment area. Weekend rest breaks allow normal cells to recover. The total dose of radiation and the number of treatments a patient needs depend on the size and location of the cancer, the type of tumor, the patient's general health and other factors.