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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 cm2 are studied for photon beam energies of 60Co, 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 overestimation of the calculated dose in the cylindrical configuration up to about 6% for a 20 x 20-cm2 60Co 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

1995

Språk

Engelska

Sidor

74-80

Publikation/Tidskrift/Serie

Radiotherapy and Oncology

Volym

37

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Elsevier

Ämne

  • Radiology, Nuclear Medicine and Medical Imaging

Nyckelord

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

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 1879-0887