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Tommy Knöös

Sjukhusfysiker

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Limitations of a pencil beam approach to photon dose calculations in the head and neck region

Författare

  • Coen Hurkmans
  • Tommy Knöös
  • Per Nilsson
  • Gudrun Svahn-Tapper
  • Hans Danielsson

Summary, in English

The inherent limitations of a specific pencil beam model have been studied when applied to a cylindrical geometry simulating the neck region. A comparison is made between measured and calculated absorbed dose in a cylindrical phantom. The goal is to quantify the deviations in the absorbed dose level, i.e., the dose per monitor unit, when photons are used for the treatment of head and neck tumours. Square fields ranging from 5 x 5 up to 30 x 30 cm[super:2] are studied for photon beam energies of [super:60]Co, 4, 6 and 18 MV. Ionisation chamber measurements have been performed in the cylinder as well as in two other configurations in order to trace the origin of possible deviations. For 18 MV no significant deviations are found between measurement and calculation in the cylindrical configuration. For the lower energies, an over-estimation of the calculated dose in the cylindrical configuration up to about 6% for a 20 x 20-cm[super:2] [super:60]Co field has been found. These deviations have been traced to the basic approximation for the integration volume for phantom scatter calculations inherent in this pencil beam implementation.

Avdelning/ar

  • Medicinsk strålningsfysik, Lund

Publiceringsår

1996

Språk

Engelska

Sidor

38-38

Publikation/Tidskrift/Serie

Medical Dosimetry

Volym

21

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging

Nyckelord

  • Head and neck region
  • Pencil beam algorithm
  • Dose planning
  • Radiotherapy
  • Patient modelling

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1873-4022