The Physics of Proton Therapy

The Physics of Proton Therapy

This highly complex treatment begins with a very basic ingredient. Hydrogen, the simplest and most abundant element in the universe, is composed of just one proton and one electron. Through a process called electrolysis, powerful magnets strip protons from the hydrogen atoms in water. The protons are then injected into a machine called a cyclotron. Within fractions of a second, the cyclotron accelerates the protons to two-thirds the speed of light, using electric fields.  

The more times they circle, the faster the protons travel and the more energy they attain. The more energy they attain, the deeper they can penetrate in a patient. 

When the protons reach the energy needed, they are ready to be directed to the room where the patient awaits treatment. The positively charged protons are steered using magnetic fields. SCCA Proton Therapy, A ProCure Center’s transport system is made up of a series of magnets that bend, focus, and route the proton beam.

Our treatment process is monitored and overseen by radiation oncologists, medical physicists, engineers, and other experts to ensure that patients receive their prescribed treatment safely and accurately. Our radiation oncologists take into account the location, shape, and tissue density of the tumor in calculating the number of protons to be utilized. These calculations also include the depth that the protons must travel to determine the speed and shape of the proton beam.

Once the proton beam is guided to the treatment chamber, a 21,000-pound electromagnet guides the beam to the patient through a nozzle. A shaping device shapes the beam; a second device called a compensator distributes the protons into three dimensions and conforms the beam to the required depth. Because each patient’s tumor shape, size and location are unique, this step of the process is essential in “sculpting” the beam to maximize the dose to the tumor while minimizing exposure to the healthy tissues that surround it.