title: Impact of beam quality on megavoltage radiotherapy treatment techniques utilizing gold nanoparticles for dose enhancement.
abstract: 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.
authors.affiliation: Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Tsiamas
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Fulya
authors.initials: F
authors.lastname: Cifter
authors.forename: Wilfred F
authors.initials: WF
authors.lastname: Ngwa
authors.forename: Ross I
authors.initials: RI
authors.lastname: Berbeco
authors.forename: Constantin
authors.initials: C
authors.lastname: Kappas
authors.forename: Kiriaki
authors.initials: K
authors.lastname: Theodorou
authors.forename: Karen
authors.initials: K
authors.lastname: Marcus
authors.forename: Mike G
authors.initials: MG
authors.lastname: Makrigiorgos
authors.forename: Erno
authors.initials: E
authors.lastname: Sajo
authors.forename: Piotr
authors.initials: P
authors.lastname: Zygmanski
mesh_terms: D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000627:therapeutic use*; D009010:Monte Carlo Method; D011829:Radiation Dosage; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated
chemical_list: D006046:Gold