Linear Accelerators — A Key Part in the Battle Against Cancer

Fighting cancer involves a multidisciplinary attack. Typically, the big three weapons a cancer patient has available to them are surgery, chemotherapy and radiation therapy. Of those three, radiation therapy is often the least understood — perhaps because of how technologically advanced the process is.

About half of all cancer patients receive some type of radiation therapy during their treatment process. The most commonly used device to delivery this therapy is called a linear accelerator.

Never heard that term before? Most haven’t.

Linear accelerators shape the high X-ray beams used for radiation therapy to treat cancer and/or prevent additional tumor growth by damaging the cancer cells to stop them from growing and dividing. The X-rays can conform to the shape of a patient’s tumor to precisely target cancer cells while preserving the normal tissue that surrounds them.

At Memorial’s Regional Cancer Center, our radiation therapy team has commissioned two new top-of-the-line Varian TrueBeam linear accelerators over the past year. The first accelerator has been functional since December 2010, and the second since Aug. 29. The machines are the 37th and 118th produced, respectively. These new machines use high-precision beams to treat the tumor in a manner that’s nearly seven-times quicker than previous accelerators and more accurate, meaning a better overall experience for patients.

“It really advances the way you do treatment planning by delivering higher doses of radiation with better precision faster than you can on other types of equipment,” said Linda Jones, DNS, RN, AOCN, administrator of Oncology, Pulmonary and Clinical Research Services at Memorial. “We anticipate a lot fewer side effects and long-term complications for patients because it reduces the amount of normal tissue in the treatment field.”

Here’s how radiation therapy works at Memorial:

When a patient arrives for his or her first radiation therapy treatment, the first step is a CT scan to get 3D images of the tumor being treated. The patient’s physician (a radiation oncologist) then determines the daily dose and number of radiation treatments the patient needs. The images are sent electronically to a dosimetrist (a radiation dosing specialist), who uses the physician’s prescription to decide the size, strength and angle of the radiation beams for the patient’s treatment, with the goal being to treat the tumor as effectively as possible while reducing the possibility of damage to any surrounding structure or tissue.

An electronic treatment plan is developed for each patient and is entered into an information system that runs the TrueBeam machine, therefore reducing the chance for human error. In the treatment area, a radiation technologist ensures the patient is positioned in the exact same way for every treatment, with the help of molds and laser crossbeams. The machines can move 180 degrees around the patient and deliver the beam from any angle. Image-guided technology, such as a built-in CT and X-ray, can help ensure the radiation beam is aiming at the right area.

The accelerators, which use 14 computers each, also function with a high degree of safety; the machine shuts off if anything seems off with the treatment plan or the machine itself.

“It really is the latest technology available in the marketplace,” Jones said.

Radiation therapy is used to treat cancers of the lung, breast, brain, prostate, cervix, uterus, and other body organs. Most radiation therapies are scheduled as five treatments a week, given Monday through Friday for a period of six to eight weeks.