Having proved its value in conventional radiation therapy over the past 10 years, CT-on-rails is now finding its way into proton therapy treatment rooms. The Trento Proton Therapy Center, part of the Azienda Provinciale per i Servizi Sanitari (APSS) health authority, is the first center to enjoy an IBA-installed in-room CT-on-rails. “We are intent on staying on the cutting edge of technology, embracing every feature that brings our proton therapy installation closer to its full potential,” says Dr. Marco Schwarz, Head of proton Medical Physics of the Trento Proton Therapy Center.
Whereas Cone Beam CT (CBCT) as an imaging modality mainly contributes to highly accurate positioning of the patient, CT-on-rails goes much further. CT-on-rails brings proton therapy one step closer to adaptive treatment, which will allow real-time adaptation to the configuration of the patient. Tumor shrinking, weight loss or even organ movement would thus be accounted for at each treatment session. Today, CT-on-rails allows for online plan verification, using high quality 3D imaging before each treatment session to evaluate the dose distribution. If necessary, planning can be adapted offline. Ongoing research is working towards online replanning, which will require quick indicators immediately revealing target accuracy and integrated contour propagation.
The clinical staff at APSS has started the clinical commissioning process, in order to integrate the new imaging option into their treatment protocols. They will work in close collaboration with IBA engineers to further develop the clinical applications of CT-on-rails positioning and the role it can play in adaptive treatments. Together with the two European centers that have already installed CT-on-rails and the installations of this imaging modality that are pending, IBA hopes to found a motivated user group contributing knowledge and experience to bring the technology to its full potential. Ultimately, IBA believes that the combination of Pencil Beam Scanning (PBS) as a delivery method, Cone Beam CT (CBCT) as a positioning tool, and CT-on-rails to assist with treatment plan verification will reduce the error margins of proton therapy treatment to such an extent that it enables better treatment protocols such as hypofractionation. Reducing the number of fractions required per patient to five to 10 from the current average of 25 to 35 would mean a significant reduction in the cost of treatment, while the combination of technologies would permit better tumor control – a goal IBA is eager to support.
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