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A multiplicative correction factor for tissue heterogeneities.

Abstract：

:A new multiplicative correction factor for tissue heterogeneities based on an exact expression for homogeneous non-unit-density media is proposed. O'Connor's density scaling theorem is invoked to evaluate the medium-specific tissue-maximum ratios used in the exact formulation. Monte Carlo calculations were performed at energies ranging from 60Co to 15 MV to test the technique for single- and multiple-slab geometries as well as for the clinical benchmark problem described recently by Orton et al consisting of a six-field lung plan. Within the level of statistical uncertainty (less than 2%) in the Monte Carlo calculations, the new correction factor agrees with the calculated data for single slabs of non-unit-density material. For the multiply layered geometries, the correction factor accurately represents the data beyond the build-up region at any interface, but is less reliable close to a boundary. For high energies, however, it is more accurate in the build-up region than other commonly used correction techniques such as the ratio-of-TMR or Batho methods. For all energies considered, the new correction factor agrees with the data measured by Orton et al to within 1.5%. It is more accurate than other correction factors considered by Orton et al at high energies, and is competitive with the Batho and equivalent TAR methods at low energies.

journal_name

Phys Med Biol

journal_title

Physics in medicine and biology

authors

Petti PL,Siddon RL,Bjärngard BE

doi

10.1088/0031-9155/31/10/005

subject

Has Abstract

pub_date

1986-10-01 00:00:00

pages

1119-28

issue

10

eissn

0031-9155

issn

1361-6560

journal_volume

31

pub_type

杂志文章

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