Advantages of Proton
When considering cancer treatment, it is important to find therapies that are both effective and limit side effects as much as possible. A non-invasive treatment, proton therapy has become a trusted method for accurately targeting tumors and minimizing damage to healthy tissues, thus reducing side effects and providing improved quality of life both during and following treatment.
Both standard X-rays/conventional radiation therapy and proton therapy attack tumors by preventing cancer cells from dividing and growing. The difference between the two therapies is that protons can precisely target the tumor, allowing patients to receive higher, more effective doses, and reducing damage to healthy tissue near the tumor. The chart below shows how protons eliminate radiation to the brain stem and X-rays do not.
Unlike proton therapy, conventional radiation therapy uses x-rays which enter and exits the body, potentially causing damage to the healthy tissue that surrounds the tumor being treated. However, at the Provision Center for Proton Therapy, our pencil beam scanning capabilities allow our oncologists to target treatment to a specific area, hitting the tumor with a high-energy dose of protons that enter the tumor with accuracy, then stop in its tracks, limiting collateral damage to healthy tissues. 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.
The chart below shows how protons eliminate radiation to the brain stem while X-rays do not.
When referencing the chart below, 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.
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 in two of its three treatment rooms. 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.