About Proton Therapy

Proton therapy is an advanced form of radiation therapy that uses a single beam of high-energy protons to treat various forms of cancer.

Just as with conventional radiation therapy protons treat tumors by directing radiation into the tumor site where doses of radiation destroy cancerous cells. However, unlike conventional radiation therapy, the timing and dosage of the protons’ energy can be controlled, allowing the maximum energy to be deposited directly into the tumor and limiting damage to nearby healthy tissue. As a result, the important organs and tissues surrounding the cancer are better protected from unnecessary radiation, thus minimizing or completely avoiding treatment-induced side effects, such as nerve damage with resulting neurologic dysfunction, as well as avoiding other complications such as breathing difficulties, feeding tubes, nausea, impotence, secondary cancers and others.

How it Works

When doses of protons (positively charged parts of an atom) enter the body, they deposit most of their energy at a specific target, destroying cancerous cells and preserving surrounding healthy tissue. This differs from conventional radiation, which uses x-rays that have a higher entrance dose and exit dose before and after the tumor. Reducing damage to surrounding healthy tissue and critical organs results in a lower chance for side effects and secondary cancers.

Our treatment rooms use pencil beam scanning which further increases the precision of proton therapy, allowing the tumor to be directly targeted with aggressive doses of radiation. Pencil Beam Scanning (PBS) allows clinicians to treat or “paint” a tumor using the proton beam at a precisely configured range, and to adjust the intensity of the beam to achieve the appropriate dose. PBS has truly revolutionized proton therapy, offering increased flexibility in dose shaping and improved dose conformality. Therefore, clinicians can treat larger and more complex tumors, while at the same time sparing more healthy tissue. Large and non-contiguous targets benefit especially from pencil beam scanning proton therapy. Clinicians can deliver high doses of proton radiation therapy and sculpt doses to the complex shape of an individual tumor—and therefore can be used for tumors next to critical structures. Pencil beam scanning proton therapy, produces fewer neutrons, further reducing doses to normal, healthy tissue. In the vast majority of cases, pencil beam scanning requires no beam-modifying devices, physical compensator or apertures which allows for rapid, flexible re-planning without the need to fabricate, and manually insert, new beam-shaping devices.

How do I know if it’s for me?

A non-invasive treatment, proton therapy for cancer is best used to treat individuals with a localized tumor, in which the cancer has not spread to other parts of the body and in situations in which tumors cannot be removed surgically or, in some cases, require radiation therapy in addition to surgery. Proton therapy may be combined with other treatment options, depending on the specific details of your case.

Pencil Beam

This new way of distributing protons to a tumor site has expanded the usefulness and applicability of proton therapy, because it allows a greater deal of customization and precision in cancer treatment.

Pencil beam scanning is a method in which a proton beam spot is moved by magnetic scanning while the beam intensity is adapted simultaneously to allow protons to be delivered to one specific spot, about the size of a dry-erase marker tip, in the patient’s body. Previous methods delivered the dose of radiation to the entire site at one time, making it difficult to accommodate for variations in tumor structure or volume.

Provision offers pencil-beam scanning. The technology has opened the door for a number of additional tumor sites to become candidates for proton therapy including lung, liver, breast esophagus, pelvic, large sarcomas, high risk prostate and mediastinal tumors as well as re-irradiation of recurrent tumors.

Pencil beam scanning reduces the radiation dose by 25 percent compared to existing methods of proton delivery. It has expanded the 20-30 percent of cancers considered good candidates for proton therapy to 80 percent of cancers.

When referencing the chart above, imagine that the Y axis (radiation dose) is the surface of a patient’s skin and the area between the dotted line is a tumor. The goal of treatment is to deliver the proper dose of radiation directly to the tumor while limiting the amount of exposure to surrounding healthy tissue. The sloping gray area shows how X-rays deliver a dose. To deposit the proper amount of energy into the tumor, conventional X-rays must irradiate much of the healthy tissue in front of it, and by their nature they continue to penetrate through the tumor and irradiate much of the healthy tissue behind it. Protons deliver their dose in a very different way. As the orange area shows, they enter the patient at a low dose, then, at a precise depth, they deliver a large burst of energy. Immediately after this burst, they stop completely. To treat the entire tumor, additional protons are sent in at lower doses. In this way, protons completely irradiate the tumor while limiting collateral damage. The areas shaded in gray show the additional radiation exposure to healthy tissue by X-rays compared with protons. Proton treatment delivers a dose in a more accurate, more efficient way, attacking the cancer and sparing the rest of the body.

Although it is similar to conventional radiation therapy, protons are more precise, the proton beam is fine-tuned with millimeters of accuracy to deliver maximum energy within a controlled range of the tumor. Proton treatment can also be combined with radiation, chemotherapy and biological treatments, depending on the cancer type to provide better outcomes and less tissue damage. Also, Proton treatment greatly improves pediatric outcomes.

Cancers We Treat

Get the facts to decide if proton therapy is the right treatment for you.

Proton Therapy System

Learn more about the next generation of proton therapy.