Magnetic confinement of radiotherapy beam-dose profiles

Abstract

We have used electron and photon beams from the 50 MV electron microtron at UM Hospital together with a large-bore 3.5T superconducting solenoid to demonstrate the magnetic confinement of HE electron and photon beam-dose profiles for typical radiotherapy beams. The HE electron beams in particular exhibit a large reduction in penumbra when entering a tissueequivalent phantom and, in addition, confinement of the secondary electrons produced by the primary beam. Likewise photon beams show a similar confinement of the dose from secondary electrons. While the results resemble features predicted from Monte Carlo calculations, there are a number of anomalous details in the actual experimental data which serve to illustrate the problems associated with practical clinical implementations. However the data suggest that in certain cases HE electrons may provide a cost-effective alternate to proton or HI radiotherapy beams and, also, improve the dose profile for HE photon beams.

Magnetic confinement of electron and photon radiotherapy dose: A Monte Carlo simulation with a nonuniform longitudinal magnetic field

“…Since relatively compact electron accelerators, with energy of 20-100 MeV, together with large-bore, high-field superconducting solenoid magnets are either commercially available now or feasible in the near future, 15 we have done simulations in order to further demonstrate the possibilities of magnetically confined electron-beam radiation therapy. As an example, we have done a simple simulation of a multibeam stereotactic treatment dose profile with 35 MeV electron beams, which would be typical of a modest-size microtron adapted for clinical use.…”

“…The issue of providing a suitable magnetic-field configuration in a clinical setting has previously been discussed. 15 Very large bore, high-field superconducting solenoids including split-coil magnets are commercially available with some systems requiring no cryogens ͑LN or LHe͒. The latter are particularly well suited for mounting on a gantry suitable for stereotatic treatment.…”

“…However, high-energy electron beams with a suitably focused and confined dose profile could prove useful as a cost-effective alternative to proton-and other ion-therapy beams, or as an additional modality in electron and photon radiation therapy. 15,16 The main purpose of the present work was to accurately simulate the results of the existing experiment 14 and to understand the origin of a number of "anomalies" seen in the dose profiles obtained in the experiment. In this study the Monte Carlo code PENELOPE 17,18 was utilized to realistically simulate the experiment.…”

High energy electron beams shaped with applied magnetic fields could provide a competitive and cost‐effective alternative to proton and heavy‐ion radiotherapy

“…[1][2][3]5 However, this issue can be addressed definitively only by further research including realistic treatment simulations and animal clinical trials.…”

“…The dose profile resembles a degraded Bragg curve. 2,3 This feature could be exploited in conformal radiotherapy to furnish an alternative to proton or heavy-ion radiotherapy, at least for certain types of tumors, and to provide an economical, on-site electron-beam therapy facility for many hospitals. High-energy electron accelerators ͑e.g., linacs and microtrons͒ and electron-beam gantries are affordable by many hospitals.…”