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Crister Ceberg

Avdelningschef

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Transmission measurements in air using the ESTRO mini-phantom

Författare

  • Stefan Johnsson
  • Crister Ceberg
  • Tommy Knöös
  • Per Nilsson

Summary, in English

The aim of this work is to study the possibility of using the ESTRO mini-phantom for transmission measurements of primary kerma in water at a point free in air. We discuss in-air measurements in general, with special attention given to in-air equivalent measurements using a water equivalent mini-phantom. The study includes four different photon energies (4, 6, 10 and 18 MV), where scoring of dose and primary kerma inside a mini-phantom in narrow beam geometry is performed with the Monte Carlo code EGS4. The results reveal that relative measurements (i.e. with and without a water absorber present) at 10 cm depth in a mini-phantom do not represent the variation of primary kerma in water at a point free in air (deviations as large as 7% at 4 MV are observed). Minimum deviations are obtained at depths somewhat larger than the depth of dose maximum. The observed deviations are due to a considerable beam hardening in the water absorber, which changes the amount of attenuation and scatter inside the mini-phantom.

Avdelning/ar

  • Medicinsk strålningsfysik, Lund

Publiceringsår

1999

Språk

Engelska

Sidor

2445-2450

Publikation/Tidskrift/Serie

Physics in Medicine and Biology

Volym

44

Avvikelse

10

Dokumenttyp

Artikel i tidskrift

Förlag

IOP Publishing

Ämne

  • Radiology and Medical Imaging

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 1361-6560