Clinical Electron Beam Physics

  • Francis J. Bova
Part of the Medical Radiology book series (MEDRAD)


As in all treatment planning, the aim of the procedure is to derive a plan for irradiating the target tissues while ensuring optimum sparing of nontarget tissues. With photon beam planning, the beam is exponen­tially absorbed by the tissues beyond the target depth, whereas the finite range of electrons provides a powerful tool for limiting the dose to deep-seated tissues. As always, with any advantage comes disad­vantage. With electrons, these disadvantages involve the rapid decrease in field uniformity as one moves farther away from the point of final collimation. With electrons, one also experiences rapid and significant changes in the depth-dose curves for very small field sizes, and the rapid change in depth of dose penetration when traversing inhomogeneities. There are also difficulties in accurately predicting a virtual source position and subsequently predicting output at extended source-to-surface distances (SSDs). Furthermore, output for irregularly shaped fields is difficult to predict.


Electron Beam Dose Distribution Field Size Output Factor Surface Dose 
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Copyright information

© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • Francis J. Bova
    • 1
  1. 1.Department of Radiation OncologyUniversity of FloridaGainesvilleUSA

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