Determination of the tissue attenuation factor along two major axes of a high dose rate (HDR) 192Ir source

Sang Hyun Cho, Renate Muller-Runkel, William F. Hanson

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Quantitative information on photon scattering around brachytherapy sources is needed to develop dose calculation formalisms capable of predicting dosimetric parameters with minimal empiricism. Photon absorption and scatter around brachytherapy sources can be characterized using the tissue attenuation factor, defined as the ratio of dose in water to water kerma in free space. In this study, the tissue attenuation factor along two major axes of a high dose rate (HDR) 192Ir source was determined by TLD measurements and MCNP Monte Carlo calculations. A calculational method is also suggested to derive the tissue attenuation factor along the longitudinal source axis from the factor along the transverse axis, using published anisotropy data as input. TLD and Monte Carlo results agreed with each other for both source axes within the statistical uncertainty (~±5%) of Monte Carlo calculations. Comparison with published data, available only for the transverse source axis, also showed good agreement within ±5%. The Shape and magnitude of the tissue attenuation factor are found to be remarkably different between the two axes. The tissue attenuation factor reaches a maximum value of about 1.4 at 8 cm from the source along the longitudinal source axis, while a maximum value of about 1.04 occurs at 3-4 cm from the source along the transverse axis. The calculated tissue attenuation factor along the longitudinal source axis generally reproduced the TLD and Monte Carlo results within ±5% at most radial distances.

Original languageEnglish (US)
Pages (from-to)1492-1497
Number of pages6
JournalMedical physics
Volume26
Issue number8
DOIs
StatePublished - Aug 1999

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Thromboplastin
Brachytherapy
Photons
Empiricism
Water
Anisotropy
Uncertainty

Keywords

  • HDR Ir source
  • Monte Carlo calculation
  • TLD
  • Tissue attenuation factor

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

Cite this

Determination of the tissue attenuation factor along two major axes of a high dose rate (HDR) 192Ir source. / Cho, Sang Hyun; Muller-Runkel, Renate; Hanson, William F.

In: Medical physics, Vol. 26, No. 8, 08.1999, p. 1492-1497.

Research output: Contribution to journalArticle

Cho, Sang Hyun ; Muller-Runkel, Renate ; Hanson, William F. / Determination of the tissue attenuation factor along two major axes of a high dose rate (HDR) 192Ir source. In: Medical physics. 1999 ; Vol. 26, No. 8. pp. 1492-1497.
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