Electron beam therapy with transverse magnetic fields

Detailed Monte Carlo electron transport simulations were carried out for the purpose of investigating the possibility of improving electron dose distribution for therapeutic applications, by using transverse magnetic fields. The case studied here is that of a 15 MeV electron beam of 6 cm diameter. The electrons pass through 4 cm of field-free tissue and a transverse magnet:ic field is applied for depth greater than 4 cm. A field of 3 T was found to improve the skin sparing factor by a factor of 2, when compared to field-free irradiation. A field of 2 T could also have a significant effect although less pronounced than 3 T while, for the case at hand, a magnetic field of only 1 T is not effective. The results here include detailed energy deposition contours in three dimensions. (C) 1999 American Association of Physicists in Medicine.