Clinical Electron Dosimetry John Spindler, CMD Louise Francis, CMD

History of Electron Therapy Early clinical use Modern clinical use Electron vs Orthovoltage Treatment

Electron Production How are electrons produced Useful energy range Electron Scattering

Electron Production

Electron Characteristics Relatively uniform dose distribution within first few centimeters of tissue followed by rapid fall off. Less skin sparing and less penetrating . Constriction of higher isodose lines and ballooning of lower isodose lines. Bremsstrahlung tail.

Electron Characteristics

Electron Characteristics

Electron Characteristics Practical Range Rp(cm)=MeV/2 Therapeutic Range 90%isodose=MeV/4 80%isodose=MeV/3

Electron Characteristics 3 4

Clinical Applications Choosing electron energy rule of thumb Consider not only what you are trying to treat, but also what you may be trying to avoid Remember to include adequate margin when drawing electron fields

Electron Monitor Units %