Proton therapy is a major technological advance in cancer care. The effectiveness of proton therapy is due to the way the energy is delivered at a prescribed depth known as the Bragg Peak.
Varian’s ProBeam® system is at the forefront of the industry, having created the world’s first commercially available pencil beam scanning system, which is the most precise form of proton therapy available.
Only pencil beam scanning is able to deliver intensity-modulated proton therapy (IMPT), which is recognized for its effectiveness and conformity of dose delivery, and considered an advance over other proton therapy delivery methods.
Currently, proton therapy as a whole—offered at 48 centers worldwide—composes a small percentage of radiotherapy treatment options. But many centers are in the planning or construction phases.
Given that clinicians are able to program pencil beam scanning to the precise depth of the tumor, there are a number of advantages to both patients and clinicians:
Not all pencil beam scanning is the same. Compared to other proton systems with pencil beam scanning, the ProBeam system offers faster layer switching. The average time per layer switch with the Compact unit is less than 1 second. The ProBeam system also delivers proton therapy of 2G/L/min, with a small spot size across the full energy range. This proton therapy is delivered without the need for range shifters, even at 70-100 MeV. In addition, some single room proton systems only offer scattering technology today, which are not capable of IMPT. It’s also important to note that pencil beam scanning produces significantly fewer neutrons and their associated risk. Conversely, with passive scattering, neutrons—i.e., secondary radiation—are produced when the scattered proton beam contacts the scattering material or beam-modifying devices. This is especially important when treating children, who are at higher risk of developing neutron-induced secondary cancers later in life.
