Impact of beam quality on megavoltage radiotherapy treatment techniques utilizing gold nanoparticles for dose enhancement

This study determines the optimal clinical scenarios for gold nanoparticle dose enhancement as a function of irradiation conditions and potential biological targets using megavoltage x-ray beams. Four hundred and eighty clinical beams were studied for different potential cellular or sub-cellular targets. Beam quality was determined based on a 6 MV linac with and without a flattening filter for various delivery conditions. Dose enhancement ratios DER = D(GNP)/D(water) were calculated for all cases using the GEANT4 Monte Carlo code and the CEPXS/ONEDANT radiation transport deterministic code. Dose enhancement using GEANT4 agreed with CEPXS/ONEDANT. DER for unflattened beams is ∼2 times larger than for flattened beams. The maximum DER values were calculated for split-IMRT fields (∼6) and for out-of-field areas of an unflattened linac (∼17). In-field DER values, at the surface of gold nanoparticles, ranged from 2.2 to 4.2 (flattened beam) and from 3 to 4.7 (unflattened beams). For a GNP cluster with thicknesses of 10 and 100 nm, the DER ranges from 14% to 287%. DER is the greatest for split-IMRT, larger depths, out-of-field areas and/or unflattened linac. Mapping of a GNP location in tumor and normal tissue is essential for efficient and safe delivery of nanoparticle-enhanced radiotherapy.

[1]  E Sajo,et al.  Deterministic calculations of photon spectra for clinical accelerator targets. , 2002, Medical physics.

[2]  Moshi Geso,et al.  Enhancement of radiation effects by gold nanoparticles for superficial radiation therapy. , 2009, Nanomedicine : nanotechnology, biology, and medicine.

[3]  D. Hunting,et al.  On the role of low-energy electrons in the radiosensitization of DNA by gold nanoparticles , 2011, Nanotechnology.

[4]  J. Seco,et al.  A modification of flattening filter free linac for IMRT. , 2011, Medical physics.

[5]  Eric C Ford,et al.  How safe is safe? Risk in radiotherapy. , 2010, International journal of radiation oncology, biology, physics.

[6]  Sang Hyun Cho,et al.  Estimation of tumour dose enhancement due to gold nanoparticles during typical radiation treatments: a preliminary Monte Carlo study , 2005, Physics in medicine and biology.

[7]  Kostas Kostarelos,et al.  A Monte Carlo track structure code for electrons (~10 eV-10 keV) and protons (~0.3-10 MeV) in water: partitioning of energy and collision events , 2000 .

[8]  R. Berbeco,et al.  Applying gold nanoparticles as tumor-vascular disrupting agents during brachytherapy: estimation of endothelial dose enhancement , 2010, Physics in medicine and biology.

[9]  J. Pignol,et al.  Implications on clinical scenario of gold nanoparticle radiosensitization in regards to photon energy, nanoparticle size, concentration and location , 2011, Physics in medicine and biology.

[10]  Sang Hyun Cho,et al.  Estimation of microscopic dose enhancement factor around gold nanoparticles by Monte Carlo calculations. , 2010, Medical physics.

[11]  Wilfred Ngwa,et al.  Localized dose enhancement to tumor blood vessel endothelial cells via megavoltage X-rays and targeted gold nanoparticles: new potential for external beam radiotherapy. , 2011, International journal of radiation oncology, biology, physics.

[12]  Jim E. Morel,et al.  Physics guide to CEPXS: A multigroup coupled electron-photon cross-section generating code , 1989 .

[13]  J. Locquet,et al.  Beam energy considerations for gold nano-particle enhanced radiation treatment , 2009, Physics in medicine and biology.

[14]  H Matsudaira,et al.  Iodine contrast medium sensitizes cultured mammalian cells to X rays but not to gamma rays. , 1980, Radiation research.

[15]  Glenn R. Dickson,et al.  Biological consequences of nanoscale energy deposition near irradiated heavy atom nanoparticles , 2011, Scientific reports.

[16]  Jean Pouliot,et al.  Low dose megavoltage cone beam computed tomography with an unflattened 4 MV beam from a carbon target. , 2008, Medical physics.

[17]  Giuseppe Schettino,et al.  Nanodosimetric effects of gold nanoparticles in megavoltage radiation therapy. , 2011, Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology.

[18]  L. Toburen.  Challenges in Monte Carlo track structure modelling , 2012, International journal of radiation biology.

[19]  F. Spiers.  The influence of energy absorption and electron range on dosage in irradiated bone. , 1949, The British journal of radiology.

[20]  R. Berbeco,et al.  Gold nanoparticle-aided brachytherapy with vascular dose painting: estimation of dose enhancement to the tumor endothelial cell nucleus. , 2011, Medical physics.

[21]  I J Das,et al.  Gold microspheres: a selective technique for producing biologically effective dose enhancement. , 2000, International journal of radiation biology.

[22]  L. Sanche,et al.  Gold Nanoparticles Enhance DNA Damage Induced by Anti-cancer Drugs and Radiation , 2009, Radiation research.

[23]  Iwan Kawrakow,et al.  On the Monte Carlo simulation of electron transport in the sub-1 keV energy range. , 2011, Medical physics.

[24]  J. Humm,et al.  Dosimetry of Auger-electron-emitting radionuclides: report no. 3 of AAPM Nuclear Medicine Task Group No. 6. , 1994, Medical physics.

[25]  D. Jaffray,et al.  Irradiation of gold nanoparticles by x-rays: Monte Carlo simulation of dose enhancements and the spatial properties of the secondary electrons production. , 2011, Medical physics.

[26]  Yi Zheng,et al.  Radiosensitization of DNA by Gold Nanoparticles Irradiated with High-Energy Electrons , 2008, Radiation research.

[27]  Sang Hyun Cho,et al.  The dosimetric feasibility of gold nanoparticle-aided radiation therapy (GNRT) via brachytherapy using low-energy gamma-/x-ray sources , 2009, Physics in medicine and biology.