What is radiotherapy?

Radiation therapy, or radiotherapy, is the use of high-energy radiation from x-rays, gamma rays, neutrons, and other sources to destroy cancer cells and shrink tumors. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells (internal radiation therapy, implant radiation, or brachytherapy). Systemic radiation therapy uses a radioactive substance, such as a radiolabeled monoclonal antibody, that circulates throughout the body. Fractionated radiotherapy is administered in a series of treatment sessions over a specified period of time.

What is radiosurgery?

Radiosurgery is a radiation therapy procedure that uses a special system to precisely deliver a large radiation dose to a tumor in a single session. The goal of this non-invasive procedure is to destroy the target without surgery or harming nearby healthy tissue. It is used to treat brain tumors and other brain disorders. It is also being studied in the treatment of other types of cancer, such as lung and spinal indications. It is also called radiation surgery, stereotactic external-beam radiation, stereotactic radiation therapy, stereotactic radiosurgery, and stereotaxic radiosurgery.


Why is fast treatment important?

There are two reasons why short treatment times can be important: treatment accuracy and patient comfort. The length of  treatments with some devices can be extreme, lasting an hour or more, during which the patient must lie as still as possible. Prolonged treatment times can make the entire process even more stressful, and some physicians recommend practicing meditation during the procedure or even prescribe a sedative. Reducing the treatment time also minimizes the time where the patient may make small movements that can affect the overall accuracy of the treatment.

Varian® delivery systems are optimized for the fastest treatment delivery, improving both patient comfort and treatment accuracy.

What is the advantage of shaped beam radiosurgery?

Traditionally, circular beams are used for radiosurgery. The resulting dose of such an approach is a spherical dose volume. As most lesions are very irregular in shape, several of those spherical dose volumes have to be composed together to cover the complex tumor shape. Other systems try to move the circular beam to “paint” the dose into the tumor volume over a time. Both approaches are time consuming and do not ideally tailor the dose to the exact shape of the tumor. This can result in lower than desired irradiation to parts of the tumor and higher than desired irradiation to healthy tissue. Varian's real-time beam steering and dual sealed ion chamber helps ensure that optimal beam symmetry, flatness, and dosimetry are delivered throughout all gantry angles.

Why is it important to have a flexible radiosurgery system?

Each tumor is different. They vary greatly by patient in location, size, shape, and proximity to vital organs, making each case completely unique. To compose the ideal treatment plan for each particular tumor and patient it is important for the physician  to be able to choose from a wide range of different treatment modalities.

Varian machines enable clinicians to use all three major IMRT methods - sliding window, step and shoot, and dynamic conformal arc - either separately or in the same treatment.

Why is it important whether a system is ‘proven’?

For any treatment, the experience of the practicing physician makes an important difference. When a type of treatment is extensively researched and proven in well-known medical journals, your physician is able to draw on the experience and knowledge of leading physicians from around the world. As a result, words like “advanced,” “robotic” and “precise” are only meaningful if they are sufficiently clinically proven, and that your physician has the experience and research available to give you the best treatment possible.

Clinicians around the world depend on Varian systems to deliver treatment at the right time - the instant the tumor is on target. Whether it's day-to day repositioning of the patient or managing motion during treatment, Varian has developed the necessary Dynamic Targeting Image-Guided Radiotherapy (IGRT) process tools: cone-beam CT, radiographic, fluoroscopic, ultrasound, optical, and gating.

With Varian systems, clinicians can personalize each patient's care based on their needs and your individual clinical protocol.

What effect is the radiation likely to have on my disease?

With radiosurgery and radiotherapy, high-energy radiation beams aim to destroy tumor cells by damaging the cells and causing them to die. Visible results, as seen on a follow-up scan, might include shrinkage of the tumor or the cessation of further tumor growth. Because cell destruction and the absorption of the cells within your system is a lengthy process, it can take up to six months before the effect of the treatment is visible on a follow-up image.

Will there be any side effects?

The procedure itself is not painful. Side effects that you might experience immediately following treatment include headache and dizziness. Your doctor will discuss specific side effects with you, which may occur depending on your overall treatment plan.

What is the difference between stereotactic radiosurgery and fractionated stereotactic radiotherapy?
Radiation treatment of a tumor can either be applied in a single session with a high dose of radiation, also known as stereotactic radiosurgery, or in a series of treatments over a period of time, known as fractionated stereotactic radiotherapy. Fractionated radiotherapy involves similar total doses of radiation as radiosurgery, but the radiation is delivered in smaller amounts. Fractionated stereotactic radiotherapy allows the healthy tissue to recover from the impact of the radiation before the next treatment session.

Your doctors will recommend the technique most appropriate for you, depending on the size and location of your tumor. For fractionated treatments, a face mask is worn. Each face mask is formed to contour to the exact shape of the patient's head and will be used for each treatment fraction.

What types of conditions can be treated with the Varian Clinac linear accelerator with Dynamic Multileaf Collimator (DMLC) ?

Depending on your particular case, it can be used to treat non-cancerous and cancerous conditions such as:

• Arteriovenous malformations (AVM)
• Cavernous angiomas
• Trigeminal neuralgia
• Intractable seizures
• Parkinson’s disease
• Brain metastases / Gliomas
• Acoustic neuromas
• Pediatric brain tumors
• Recurrent brain tumors
• Pituitary adenomas
• Meningiomas of the skull base
• Craniopharyngiomas
• Spine, prostate, liver and lung malignancies

What should I expect at my treatment session?

You don’t need to bring special clothing or equipment to the hospital for your treatment. You might want to dress comfortably and bring a book or something else to keep you busy during the waiting periods. You may also bring a friend or a relative with you and he / she may stay with you during the day. However, during the actual treatment procedure, your companion will have to leave the treatment room. Please make sure to arrange for transportation home as you might feel tired after the treatment; driving is not recommended. It is possible for a complete treatment session to take place in a single-day, although your doctor will decide if your treatment should be administered in a single dose.