Ultra-fast pencil beam scanning proton therapy for locally advanced non-small-cell lung cancers: Field delivery within a single breath-hold. (September 2022)

• Record Type: Journal Article
• Authors: Maradia, Vivek; van de Water, Steven; Meer, David; Weber, Damien C.; Lomax, Antony J.; Psoroulas, Serena
• Is Part Of: Radiotherapy and oncology. Volume 174(2022)
• Page Start: 23
• Page End: 29
• Publication Date: 2022-09
• Subjects: Pencil beam scanning -- Breath-hold -- Treatment delivery efficiency -- Proton therapy -- Hypofractionation; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2022.06.018
• Languages: English
• ISSNs: 0167-8140

Abstract

Highlights: PBS proton therapy within a single breath-hold (15 sec). Hypofractionation within a single breath-hold. Treatment of moving targets. Abstract: Purpose: The use of motion mitigation techniques such as breath-hold can reduce the dosimetric uncertainty of lung cancer proton therapy. We studied the feasibility of pencil beam scanning (PBS) proton therapy field delivery within a single breath-hold at PSI's Gantry 2. Methods: In PBS proton therapy, the delivery time for a field is determined by the beam-on time and the dead time between proton spots (the time required to change the energy and/or lateral position). We studied ways to reduce beam-on and lateral scanning time, without sacrificing dosimetric plan quality, aiming at a single field delivery time of 15 seconds at maximum. We tested this approach on 10 lung cases with varying target volumes. To reduce the beam-on time, we increased the beam current at the isocenter by developing new beam optics for PSI's PROSCAN beamline and Gantry 2. To reduce the dead time between the spots, we used spot-reduced plan optimization. Results: We found that it is possible to achieve conventional fractionated (2 Gy(RBE)/fraction) and hypofractionated (6 Gy(RBE)/fraction) field delivery times within a single breath-hold (<15 sec) for a variety non-small-cell lung cancer cases. Conclusion: In summary, the combination of spot reduction and improved beam line transmission is a promising approach for the treatment of mobile tumours within clinically achievable breath-hold durations.