Verification of radiation dose in vivo during external radiotherapy treatments sing electron beams

Entrance in vivo dosimetry has probed to be a good tool to assess that the administrated dose is the dose administrated to the patient during treatment. In this paper the results of entrance in vivo measurements in a group of 643 patients undergoing external radiotherapy treatments using electron beams are presented. The calibration of diodes for entrance dose measurements in electron beams is also presented. Most of the results (97%) were within tolerance (5%). The cause of the readings being out of tolerance was, in all cases, a bad fixation of the diodes. Even if the results are within tolerance we think that in vivo dosimetry is the very last test on the administrated dose, and therefore al patients are controlled on the first session of their treatments. (Author)