PENCIL BEAM SCANNING (PBS): PROGRESS TO DATE

Spot Scanning or Pencil Beam Scanning (PBS) allows a higher degree of precision and minimizes the overall exposure and radiation to healthy tissue. Used for the first time to treat a patient at the Massachusetts General Hospital (MGH) in Boston in 2008, nearly 1,800 patients have benefited from this deliverance method (as of the end of 2014). Today, 29 rooms spread over 15 centers have implemented IBA's PBS, 21 of which are already treating patients on a daily basis at 10 different centers. An estimated 13 more rooms will bring the total to 42 PBS rooms accepted by the end of 2015, and more than 30 are expected to be treating by then. Between January and December 2014, there has been a 250% increase in the quantity of PBS fractions delivered per day.

Since 2008, delivery speed of our PBS has been decreased by a factor of six: delivering 2 Grays of proton radiation in a volume of one liter demands no longer than 50 seconds today. Faster delivery is further enhanced by the availability of multiple spot sizes. The single initial spot size of nine millimeters, now reduced by a factor of three, also makes it possible to hit the tumor with accuracy to one millimeter. Another feature that already has and will further enhance the performance of IBA's PBS installations is the addition of in-layer and volumetric repainting. Together with gating, this feature addresses the issue of motion management. This remains a clinical focus area for IBA and as the technology evolves, it will significantly broaden the scope of clinical indications that can benefit from proton therapy.