THE EFFECT OF OBLIQUE ELECTRON BEAMS TO THE SURFACE DOSE UNDER THE BOLUS


Demir B., Okutan M., Cakir A., Goksel E. O. , Bilge H.

MEDICAL DOSIMETRY, cilt.34, ss.311-316, 2009 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 34 Konu: 4
  • Basım Tarihi: 2009
  • Doi Numarası: 10.1016/j.meddos.2008.12.001
  • Dergi Adı: MEDICAL DOSIMETRY
  • Sayfa Sayıları: ss.311-316

Özet

The aim of this study is to determine file effect of bolus to the surface (lose in oblique electron incidences. Irradiations with 4.5, 6, 7.5, 9, and 12-MeV electron beams were made for the incidence angles of 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and using 3 different bolus setups: (1) unbolused (no bolus), (2) 5-mm bolus, and (3) 10-mm bolus. A set of EBT gafchromic film pieces placed oil the phantom surface was irradiated with a 400-cGy dose at D(max) for each setup. Whereas surface dose increased with increasing incidence degrees in the absence of 1 bolus. it was seen that there was a large surface dose decreasing in the presence of a bolus with increasing incidence angles. For 60 degrees incidence angle, the relative surface doses with unbolused setup were: 88.10%, 90.06%, 89.35%, 90.25%, and 97.10%; with 5-mm bolus: 66.45%, 81.20%, 99.78%, 124.43%, and 116.07%; and with 10-mm bolus: 22.65%, 45.20%, 55.20%, 65.82%, and 90.27% for 4.5, 6, 7.5, 9, and 12 MeV, respectively. The use of bolus in the treatment of highly oblique surfaces with low-energy electron beams significantly decreases the surface dose. (c) 2009 American Association of Medical Dosimetrists.