Issues involved in absorbed dose in electron treatments

• DOI: 10.22533/at.ed.3172252201115

• Palavras-chave: electrons, radiotherapy, absorbed dose

• Keywords: electrons, radiotherapy, absorbed dose

• Abstract:

  When a beam of radiation falls on a patient (or simulator), the absorbed dose varies with depth, characterizing a dose distribution in human tissue. This variation depends on several parameters: beam energy, depth, medium composition, field size, source distance and beam collimation system.
  In the case of radiotherapy treatments with electron beams, the biggest advantage lies in the shape of the dose distribution curve in depth on the central axis, especially in the range of 6 to 15 MeV. This dose distribution curve is characterized by an almost uniform dose region followed by a rapid drop in dose. This feature is a clinical advantage over other conventional megavoltage photon treatment modalities.
  Because of differences in electron beam generation and collimation, the depth dose distribution and surface dose may be different for different clinical treatment accelerators. In clinical practice, however, it is not sufficient to specify only the beam energy, but several parameters that characterize the dose variation in depth along the central axis of the electron beam. This step is fundamental in the procedure for calculating the dose administered to the patient. This section defines some parameters that allow characterizing the dose distribution in the human body.