title: Angular dose anisotropy around gold nanoparticles exposed to X-rays.
abstract: Gold nanoparticle (GNP) radiotherapy has recently emerged as a promising modality in cancer treatment. The use of high atomic number nanoparticles can lead to enhanced radiation dose in tumors due to low-energy leakage electrons depositing in the vicinity of the GNP. A single metric, the dose enhancement ratio has been used in the literature, often in substantial disagreement, to quantify the GNP's capacity to increase local energy deposition. This 1D approach neglects known sources of dose anisotropy and assumes that one average value is representative of the dose enhancement. Whether this assumption is correct and within what accuracy limits it could be trusted, have not been studied due to computational difficulties at the nanoscale. Using a next-generation deterministic computational method, we show that significant dose anisotropy exists which may have radiobiological consequences, and can impact the treatment outcome as well as the development of treatment planning computational methods.
authors.affiliation: Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, USA.
authors.forename: Sherif M
authors.initials: SM
authors.lastname: Gadoue
authors.affiliation: Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, USA; Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA.
authors.forename: Dolla
authors.initials: D
authors.lastname: Toomeh
authors.affiliation: Department of Radiation Oncology, Brigham and Women's Hospital, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, USA.
authors.forename: Piotr
authors.initials: P
authors.lastname: Zygmanski
authors.affiliation: Department of Physics and Applied Physics, Medical Physics Program, University of Massachusetts Lowell, Lowell, MA, USA. Electronic address: Erno_Sajo@uml.edu.
authors.forename: Erno
authors.initials: E
authors.lastname: Sajo
mesh_terms: D016880:Anisotropy; D006046:Gold / Q000627:therapeutic use*; D053768:Metal Nanoparticles / Q000627:therapeutic use*; D009010:Monte Carlo Method; D011879:Radiotherapy Dosage; D014965:X-Rays
chemical_list: D006046:Gold
keywords: Dose anisotropy; Dose enhancement; Gold nanoparticles; Radiotherapy