Variations of tumor control and rectum complication probabilities due to random set-up errors during conformal radiation therapy of prostate cancer

Gabriela Ragazzi, Paola Mangili, Claudio Fiorino, Giovanni Mauro Cattaneo, Angelo Bolognesi, Michele Reni, Riccardo Calandrino

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Abstract

Background and purpose: The effect of random set-up errors on tumor control probability (TCP) and rectum complication probability (NTCP) on 3D conformal treatment planning of prostate cancer has been investigated by applying the convolution method originally proposed by Leong (Leong, J. Implementation of random positioning error in computerized radiation treatment planning systems as a result of fractionation. Phys. Med. Biol. 32: 327-334, 1987). Materials and methods: The combined influence of the standard deviation of the random shifts probability distribution (σ) of the dose and of the Beam's-eye-view margin (M) between the clinical target volume (CTV) and the edge of the blocks have been investigated in two patients. Results and conclusions: Random set-up error has been found to decrease TCP (for a typical 70 Gy CTV mean dose) by up to 6% for a 1 cm margin (σ = 7 mm). When M is equal to or larger than 1.5 cm, no relevant effects on TCP are obtained. Maximum acceptable TCP values (corresponding to a rectum NTCP equal to 5%) have been derived and the dependence on σ and M has been investigated.

Original languageEnglish
Pages (from-to)259-263
Number of pages5
JournalRadiotherapy and Oncology
Volume44
Issue number3
DOIs
Publication statusPublished - Sep 1997

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Keywords

  • Biological models
  • Conformal radiotherapy
  • Margins in radiotherapy
  • Optimization in radiotherapy
  • Positioning errors

ASJC Scopus subject areas

  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Urology

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