Particle Therapy vs. Proton Therapy – Choosing the right terminology 

So, is it Particle or Proton Therapy? Carbon or Ion Therapy?  Or Radiation Therapy?  The language around this type of cancer treatment can get complicated quickly.   

The best way to look at all of this is to think of it as a tree diagram.  Radiation Therapy is the broadest term.  It encapsulates Particle Therapy, External Beam X-Ray Therapy, and Brachytherapy generally.  Radiation Therapy is different from Radiology (imaging) in that when radiation is used therapeutically, it tends to be far more powerful than when used for imaging, powerful enough to damage the DNA of cancer cells and cause them to die.  In Imaging, the power is much lower, causing little to no damage to cells. 

Underneath the larger grouping of Particle Therapy is Proton Therapy and Ion Therapy (or Heavy Ion, the terms are often used interchangeably).  The main difference is what is being accelerated.  Proton Therapy accelerates the protons which are taken from a hydrogen atom.  These are the smallest particles with a mass, and therefore generally easier to accelerate, requiring smaller (though still very large) equipment to accelerate and deliver them to a patient.  Ion Therapy starts to work up the periodic table, accelerating larger ions (hence the term “Heavy” Ion).  The most common element to be used is Carbon, though other elements, like Oxygen and Helium, are also used.  The reason behind the choice between protons and ions typically comes down to a cost-benefit decision.  The larger the particle, the more damage it can do to the cancerous cells, but the larger, and more expensive, the equipment that is required to accelerate it to a useful power.  Typically, accelerators capable of accelerating Ions have only been found in laboratories focused on nuclear physics, and not well suited for patient care.  However, as technology advances, this paradigm is shifting, with several high-profile institutions in the US considering or actively pursuing particle centers capable of Ion therapy, in addition to proton therapy. 

Until recently, Proton Therapy has been the predominant form of Particle Therapy used worldwide, but the use of Ion Therapy is steadily growing.  BR+A has been at the forefront of facility design and engineering and has not only worked on many of the Proton Therapy centers worldwide but has worked on several Ion Therapy project concepts as well.  BR+A has also worked with many of the equipment vendors who provide both Proton Therapy and Ion Therapy systems to refine their owner requirements and understand how best to build a facility to ensure system performance and reliability, which being conscious of cost control for their customers.  Given this experience, and the growing interest in pursuing Ion Therapy worldwide, it only makes sense to use the term Particle Therapy going forward and broaden our focus to all of the way in which Particle Therapy can be brought to bear to help cancer patients worldwide.