1 Dana-Farber Cancer Institute, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115 and Medical Physics Department, Joseph Fourier University, Grenoble 38000, France
2 Dana-Farber Cancer Institute, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115 and Medical Physics Department, Medical School, University of Thessaly, Larisa 41100, Greece
3 Dana-Farber Cancer Institute, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115
The aim of this study is to quantify and to compare the dose enhancement factor from goldnanoparticles (AuNP) to tumor endothelial cells for different concentrations of AuNP, and clinical MV beam configurations.
Tumor endothelial cells are modeled as slabs measuring 10 × 10 × 2μm. A spherical AuNP is simulated on the surface of the endothelial cell, within the blood vessel. 6 MV photon beams with and without the flattening filter are investigated for different field sizes, depths in material and beam modulation. The incident photon energy spectra for each configuration is generated using EGSnrc. The dose enhancement in the tumor endothelial cell is found using an analytical calculation. The endothelial dose enhancement factor is defined to be the ratio of the dose deposited with and without AuNPs.
It is found that clinical beam parameters may be chosen to maximize the effect of goldnanoparticles during radiotherapy. This effect is further amplified ∼20% by the removal of the flattening filter. Modulation of the clinical beam with the multileaf collimator tends to decrease the proportion of low energy photons, therefore providing less enhancement than the corresponding open field.
The results of this work predict a dose enhancement to tumor blood vessel endothelial cells using conventional therapeutic (MV) x-rays and quantify the relative change in enhancement with treatment depth and field size.
Received 15 October 2012Revised 29 January 2013Accepted 29 January 2013Published online 12 February 2013
The project described was supported, in part, by a Brigham and Women's Hospital Biomedical Research Institute Seed Grant and by Award No. R03CA164645 from the National Cancer Institute. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Cancer Institute or the National Institutes of Health.
Article outline: I. INTRODUCTION II. MATERIALS AND METHODS II.A. Photon energy spectra II.B. The analytical calculation III. RESULTS IV. DISCUSSION V. CONCLUSIONS
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