Encrypted login | home

Program Information

Simulation of Conformal Arc Proton Therapy Using the MEVION-S250 System Considering Beam Shaping with a Multi-Leaf Collimator

no image available
S Ferguson

S Ferguson*, S Ahmad , O Algan , T Herman , I Ali , Oklahoma Univ. Health Science Ctr., Oklahoma City, OK


SU-H2-GePD-T-3 (Sunday, July 30, 2017) 3:30 PM - 4:00 PM Room: Therapy ePoster Lounge

Purpose: To simulate and evaluate quantitatively the dose from conformal arc proton therapy utilizing the double-scattering MEVION-S250 system by aperture shaping with a multi-leaf collimator (MLC) and without patient specific compensators.

Methods: Conformal arc proton therapy was simulated using the double-scattering-Mevion-S250 proton therapy system. Plans with multiple-conformal proton beams from 10-15 were generated with the Eclipse-treatment-planning system considering conformal beams with the tumor shape at each angle that can be obtained from an MLC system. These arc plans employed range-modulation with proton beams from the different directions to cover the planning target volume (PTV) without patient specific compensators. The dose distributions from the arc plans were compared quantitatively with the 2-fields conventional plans with compensators using dosimetric parameters (Dmin,Dmax,Dmean,D95,D90,D50).

Results: The conformal arc proton plans provided superior dose coverage and sparing of normal tissues in comparison with conventional plans that used 2-fields. The entrance normal tissue and skin doses (40% lower) were lowered significantly by delivering dose from different directions over a wider angular view compared to conventional plans that have large entrance dose from only two fields. Minimum (+7%), maximum (-3%) and mean dose (same) of the PTV from arc plans were superior to conventional plans which improved dose conformity and uniformity. In this simulation, conformal arcs plans require dose delivery with multiple-beams or by continuous gantry rotation with changing the shape of MLC to conform to the tumor shape in the different angular views. Arc plans is faster than conventional plans with compensators, while, uncertainties in range-modulations and patient setup can be reduced.

Conclusion: Conformal arc proton plans have superior dose coverage and sparing of normal tissues compared to conventional plans as shown in this simulation. Large errors in patients setup and proton range modulation can be reduced while maintaining nearly the same dose delivery time.

Contact Email: