Health Matters 7/5: Radiation therapy to treat cancer becoming more precise


By: Joseph M. Pepek, M.D.

Radiation therapy is a common approach to treating many different types of cancer and has become increasingly precise as technology has improved and advanced.

Precision is paramount as radiation not only kills cancer cells, but can also affect surrounding healthy cells.

As part of its comprehensive cancer care program, the Edward & Marie Matthews Center for Cancer Care at Princeton Medical Center (PMC) now offers surface guided radiation therapy to further enhance the accuracy and precision of radiation treatment for most cancers, including left-sided breast cancer, lung cancer and gastrointestinal cancers.

How Radiation Therapy Works

Radiation therapy uses high doses of radiation to kill cancer cells, shrink tumors or slow their growth by damaging its DNA. When this damage occurs, the cancer cells stop dividing or die off.

Often radiation therapy is combined with other cancer treatments such as surgery, chemotherapy and immunotherapy to effectively treat the disease. More than half of people with cancer get radiation therapy, according to the American Cancer Society.

As the National Cancer Institute notes, radiation therapy can cure cancer, prevent it from returning or stop or slow its growth. In addition, radiation therapy can be used for palliative care to ease symptoms. For instance, radiation may be used to shrink a tumor that is causing pain, difficulty breathing or other problems.

There are two main types of radiation therapy: external beam, which comes from a machine that targets radiation to the tumor, and internal radiation therapy, known as brachytherapy which is delivered inside your body through sources such as radioactive seeds.

Side effects of radiation therapy depend on which part of the body is exposed to radiation, whether patients receive concurrent chemotherapy and how much radiation is delivered.  Most patients experience treatment-related fatigue, while others may experience more significant side effects.

Surface Guided Radiation Therapy

Surface guided radiation therapy is one of the latest techniques using external beam radiation to treat cancer.

The technique uses 3D cameras to track a patient’s position before and during radiation therapy to assist in setup and treatment accuracy. If a patient moves out of position during therapy, the radiation delivery can be automatically paused to avoid damaging healthy tissue.

While surface guided radiation therapy can be used to treat most cancers, it is particularly beneficial for patients with left-sided breast cancer.

With the heart located so close to the left breast it can be vulnerable to radiation exposure and long-term cardiac complications as a result.

To move the heart away from the breast, one option available for patients at PMC to reduce cardiac radiation dose is a technique called deep inspiration breath hold, which involves taking a deep breath and holding it while the radiation is being delivered.

Deep inspiration breath hold, combined with surface guided radiation therapy, can help ensure the heart is out of the radiation field and protected from damage.

In addition to high accuracy, other reported benefits of surface guided radiation therapy include a quicker setup time and less physical immobilization, providing more convenience and comfort for patients.

At PMC, surface guided radiation therapy as well as other external beam radiation treatments are delivered with a linear accelerator, a state-of-the-art machine that supports a variety of radiation therapy techniques designed to target tumors with precision and speed.

External beam radiation is typically delivered on an outpatient basis five days a week over a certain time span. Treatment sessions generally last between 10-30 minutes.

Learn More

Penn Medicine Princeton Health will air a pre-recorded USTREAM video with me about surface guided radiation therapy on Wednesday, July 10 at noon on its Princeton Health On Demand UStream channel at

After the episode premieres, it will remain available for on-demand viewing on the Princeton Health USTREAM channel.

To find a physician with Penn Medicine Princeton Health call 888.742.7496 or visit

Joseph M. Pepek, M.D. specializes in radiation oncology and is chief of radiation oncology at the Edward & Marie Matthews Center for Cancer Care at Princeton Medical Center.