Plane-parallel ionization chamber response in the buildup region of obliquely incident photon beams

Bruce J. Gerbi, Faiz M. Khan

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Fixed-separation plane-parallel ionization chambers have been shown to overestimate the dose in the buildup region of normally incident high-energy photon beams. This work shows that these ionization chambers exhibit an even greater over-response in the buildup region of obliquely incident photon beams. This over-response at oblique incidence is greatest at the surface of the phantom and increases with increasing angle of beam incidence. In addition, the magnitude of the over-response depends on field size, beam energy, and chamber construction. This study shows that plane-parallel ionization chambers can over-respond by more than a factor of 2.3 at the phantom surface for obliquely incident high-energy photon fields.

Original languageEnglish (US)
Pages (from-to)873-878
Number of pages6
JournalMedical Physics
Volume24
Issue number6
DOIs
StatePublished - Jun 1997

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