Imagine a 196-ton, cancer-killing machine that can target a patient's tumor with sub-millimeter precision while sparing nearby healthy tissues and minimizing side effects. In its most simple terms, that's proton therapy.
Standard radiation therapy has evolved and improved over the years and is effective in controlling many cancers. However, because X-ray beams are composed of primary photons and secondary electrons, they deposit their energy along the path of the beam, to the targeted tumor and beyond, and deliver radiation to healthy tissues before and after the tumor site. This radiation "exit dose" may cause health issues later because it can damage the normal tissue or organs near the tumor or area of concern.
The advantage of proton treatment is that the physician can control where the proton releases the bulk of its cancer-fighting energy. As the protons move through the body, they slow down and interact with electrons, and release energy. The point where the highest energy release occurs is the "Bragg peak." A physician can designate the Bragg peak's location, causing the most damage to the targeted tumor cells. A proton beam conforms to the shape and depth of a tumor, while sparing healthy tissues and organs.
How Does it Work?
The best way to understand how proton therapy works is to take a look at the physics and engineering inside the proton accelerator, or the synchrotron, and the beam delivery system.
Pencil Beam and Intensity Modulated Proton Therapy
The team at MD Anderson Proton Therapy Center continues to expand ways to use proton therapy to benefit patients. The team pioneered pencil beam proton therapy, also called scanning beam, and intensity modulated proton therapy (IMPT). We are one of the few centers worldwide offering these types of proton therapy to our patients.
Pencil beam technology and IMPT build on the benefits of proton therapy. With a proton beam just millimeters wide, these advanced forms of proton therapy combine precision and effectiveness, offering unmatched ability to treat a patient's tumor and minimizing effect on a patient's quality of life – during and after treatment. They rely on complex treatment planning systems and an intricate number of magnets to aim a narrow proton beam and essentially "paint" a radiation dose layer by layer.
Pencil beam is very effective in treating the most complex tumors, like those in the prostate, brain, eye, and cancers in children, while leaving healthy tissue and other critical areas unharmed. IMPT is best used to deliver a potent and precise dose of protons to complex or concave-shaped tumors that may be adjacent to the spinal cord or embedded head and neck or skull base, including nasal and sinus cavities; oral cavity; salivary gland; tongue; tonsils; and larynx.
Is Proton Therapy Right for You?
Proton therapy benefits patients whose tumors are solid with defined borders, meaning the cancer has not spread to other parts of the body. The noninvasive treatment does not require surgery to remove the cancer, making it ideal for inoperable tumors.