Low Z target switching to increase tumor endothelial cell dose enhancement during gold nanoparticle-aided radiation therapy

Ross I. Berbeco, Alexandre Detappe, Panogiotis Tsiamas, David Parsons, Mammo Yewondwossen, James Robar

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Purpose: Previous studies have introduced gold nanoparticles as vascular-disrupting agents during radiation therapy. Crucial to this concept is the low energy photon content of the therapy radiation beam. The authors introduce a new mode of delivery including a linear accelerator target that can toggle between low Z and high Z targets during beam delivery. In this study, the authors examine the potential increase in tumor blood vessel endothelial cell radiation dose enhancement with the low Z target. Methods: The authors use Monte Carlo methods to simulate delivery of three different clinical photon beams: (1) a 6 MV standard (Cu/W) beam, (2) a 6 MV flattening filter free (Cu/W), and (3) a 6 MV (carbon) beam. The photon energy spectra for each scenario are generated for depths in tissue-equivalent material: 2, 10, and 20 cm. The endothelial dose enhancement for each target and depth is calculated using a previously published analytic method. Results: It is found that the carbon target increases the proportion of low energy (<150 keV) photons at 10 cm depth to 28% from 8% for the 6 MV standard (Cu/W) beam. This nearly quadrupling of the low energy photon content incident on a gold nanoparticle results in 7.7 times the endothelial dose enhancement as a 6 MV standard (Cu/W) beam at this depth. Increased surface dose from the low Z target can be mitigated by well-spaced beam arrangements. Conclusions: By using the fast-switching target, one can modulate the photon beam during delivery, producing a customized photon energy spectrum for each specific situation.

Original languageEnglish (US)
Pages (from-to)436-442
Number of pages7
JournalMedical physics
Volume43
Issue number1
DOIs
StatePublished - Jan 1 2016
Externally publishedYes

Keywords

  • dose enhancement
  • nanoparticle
  • radiation therapy
  • vascular disruption

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging

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