open access
Measurement of backscattered dose at metallic interfaces using high energy electron beams
open access
Abstract
Background
The amount of backscattered electrons depends on the thickness of the backscattering metal. The electron backscatter increases with the increase in thickness of the metal until a saturation level is reached and thereafter no change in scatter enhancement is noticed.
Aim
Electron backscatter effects at metallic interfaces were analysed in this study. High energy electron beams ranging from 6 to 20 MeV were used.
Materials/Methods
Measurements were carried out with a PTW thin-window parallel plate ionization chamber and an RDM-1F electrometer. Thin sheets of aluminium, copper and lead were used as inhomogeneities. The chamber was positioned below the inhomogeneities with the gantry maintained under the couch.
Results
The electron backscatter factor (EBSF) increases with increase in energy for aluminium, copper and lead. With low atomic number materials EBSF increases with increase in scatterer thickness and for lead it attains saturation within a few millimetres.
Conclusions
The information from this study could be useful in predicting the increase in dose at the metal-tissue interface due to electron backscatter.
Abstract
Background
The amount of backscattered electrons depends on the thickness of the backscattering metal. The electron backscatter increases with the increase in thickness of the metal until a saturation level is reached and thereafter no change in scatter enhancement is noticed.
Aim
Electron backscatter effects at metallic interfaces were analysed in this study. High energy electron beams ranging from 6 to 20 MeV were used.
Materials/Methods
Measurements were carried out with a PTW thin-window parallel plate ionization chamber and an RDM-1F electrometer. Thin sheets of aluminium, copper and lead were used as inhomogeneities. The chamber was positioned below the inhomogeneities with the gantry maintained under the couch.
Results
The electron backscatter factor (EBSF) increases with increase in energy for aluminium, copper and lead. With low atomic number materials EBSF increases with increase in scatterer thickness and for lead it attains saturation within a few millimetres.
Conclusions
The information from this study could be useful in predicting the increase in dose at the metal-tissue interface due to electron backscatter.
Keywords
metallic interface; electron backscatter; beam quality; heterogeneity
About this articleTitle
Measurement of backscattered dose at metallic interfaces using high energy electron beams
Journal
Reports of Practical Oncology and Radiotherapy
Issue
Pages
117-121
Published online
2006-01-01
DOI
10.1016/S1507-1367(06)71056-2
Bibliographic record
Rep Pract Oncol Radiother 2006;11(3):117-121.
Keywords
metallic interface
electron backscatter
beam quality
heterogeneity
Authors
Sanjay Sathiyan
M. Ravikumar
Sanjay S. Supe