The effect on minimum tumor dose of restricting target-dose inhomogeneity in optimized three-dimensional treatment of lung cancer

Mark Langer, Peter Kijewski, Richard Brown, Chul Ha

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Abstract

An examination was made of the effect upon the minimum tumor dose of a limit placed on the variation of dose across target. If the required level of target dose uniformity is slightly relaxed, a substantial improvement in the minimum tumor dose might appear. It was conjectured that this effect could be seen with treatments optimally planned and evaluated in three-dimensions. A model of advanced carcinoma of the lung treated with a computer controlled accelerator was used to test this hypothesis. A mathematical program for optimizing beam weights was used to determine the largest minimum tumor dose possible. In the six cases tested, a minimum tumor dose of > 80 Gy could be delivered if a 20% inhomogeneity limit was accepted. The minimum tumor dose fell to the range 44-64 Gy when the inhomogeneity limit was tightened to 13-17%. The results imply a need to examine the choice of a required level of dose uniformity from the range of values suggested in the 2-dimensional planning literature. If a strict bound-on-dose uniformity is preserved, mechanisms - such as formal optimization - which can reduce target dose inhomogeneity will be valuable.

Original languageEnglish (US)
Pages (from-to)245-256
Number of pages12
JournalRadiotherapy and Oncology
Volume21
Issue number4
DOIs
StatePublished - Aug 1991

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Keywords

  • Computer controlled radiotherapy
  • Lung cancer
  • Optimized three-dimensional treatment
  • Target dose

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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