AbstractID: 7951 Title: Range-modulated electron radiotherapy with longitudinal magnetic field collimation
The goal of this study was to develop range-modulated electron beam (RMEB) radiotherapy with a longitudinal magnetic field collimator in order to overcome the excessive scatter and the high skin dose associated with the conventional electron beams.
Monte Carlo studies were carried out to simulate the characteristics of the electron beams generated under an axial magnetic field of 0.5-1 Tesla applied externally to the patient in the air-gap between the collimator exit port and the skin surface. A modified threedimensional pencil-beam (3DMPB) model was developed to calculate the dose distributions of the magnetically collimated electron beams. The results of the model calculations were compared with the Monte Carlo simulations. By taking the advantage of the analytical nature of the model, the beam energies and relative weights were optimized for multiple superimposed magnetically collimated electron beamlets to produce RMEB dose distributions. Our results showed excellent agreements between the
3DMPB calculations and the Monte Carlo calculations. A RMEB optimization routine was developed and tested for ideal and clinical cases that included nodal irradiation of head and neck cancers and shallow chest-wall lesion treatments. In summary, we have demonstrated the feasibility of calculating and optimizing RMEB treatments with the modified 3D pencil-beam dose model. Our future work includes beam-on tests of the
RMEB delivery using a scanning magnetic collimator constructed at our institution.
Supported in part by grants from Department of Army and Institutional Intramural Grant
Office.