Proton therapy is similar to traditional radiation therapy, but it uses a different type of energy and is much more accurate at targeting tumors.

Standard radiation therapy uses X-ray beams made up of photons, which are tiny particles that transmit light. Photons deposit energy as they travel to the tumor, into the tumor itself and beyond the tumor. This results in side effects from damage to nearby healthy tissues or organs. The dose delivered to the tumor must be limited to minimize these side effects.

Proton therapy uses protons, which are positively charged particles found in the nucleus of an atom. Proton beams enter the body with a low dose of radiation (“entrance dose”). The dose increases as it approaches the target area and deposits its maximum radiation directly to the tumor before stopping. There is no “exit dose” beyond the tumor. This means the tumor can be targeted more precisely, usually within one millimeter, and allows for the delivery of a more powerful dose of radiation.

Pencil Beam and Intensity Modulated Proton Therapy

Pencil beam scanning, also known as spot scanning, is a proton therapy technique used to treat complex tumors. Powerful magnets direct thousands of ultra-fine proton beams from multiple directions toward the tumor, creating a protective “U” shape around healthy tissue and avoiding sensitive areas.