Pencil Beam Radiation Offers More Targeted Therapy with Fewer Side Effects for Lung Cancer Patients

Pencil beam scanning technology, a targeted form of radiation treatment known as proton therapy, is now being used to treat patients with lung cancer.

Proton therapy's advantage over conventional forms of radiation from its ability to deliver radiation doses to a targeted tumor with remarkable precision that avoids surrounding tissue. This results in fewer side effects during and after treatment, and greater tumor control. Most proton therapy patients are treated with a technique known as passive scattering, which uses apertures to shape the proton beam and deliver a uniform dose to the tumor.

Pencil beam scanning proton therapy delivers a single, narrow proton beam (which may be less than a millimeter in diameter) that is magnetically swept across the tumor, depositing radiation similar to a painter's brush, without the need to construct beam-shaping devices. This technology continues to build on the patient benefits already offered with proton therapy more targeted, higher tumor dose, shorter treatment times, reduced side effects, and increased treatment options.

"The advantage lies in the beam's capacity to approach the tumor from multiple directions, creating a "U” shape around these structures and avoiding them entirely during treatment,” said James D. Cox, M.D., professor and head of the division of radiation oncology at MD Anderson Cancer Center (Houston, TX, USA). "Pencil beam is more like a very fine airbrush. Instead of needing a brass template to define the shape, the proton beam is made ultra fine to conform to the contours and landscapes of the tumor.”

MD Anderson's Proton Therapy Center, which began treating patients in May of 2006, is the first in North America and only one of three clinical centers in the world to treat patients with pencil beam scanning technology. Additionally, MD Anderson is the first center in the world to treat lung cancer patients using pencil beam scanning proton therapy.

"The unique part about lung cancer is that it's close to the esophagus, aorta, and spinal cord, and all of these critical structures are important for the body to function,” said Joe Chang, M.D., Ph.D., associate professor in MD Anderson's department of radiation Oncology. "The proton beam provides much more conformal radiation, which means higher doses to tumors and lower dosages to critical structures nearby.”

Another advantage of pencil beam scanning proton therapy is its use in patients with recurrent disease, who have already received full doses of radiation, according to Dr. Chang. In this instance, pencil beam limits or eliminates radiation to these sensitive areas. As the therapy advances, one of the next steps is using imaging tools to predict the movement of tumors, both lung and other cancers, to offer even greater precision.

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