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TH‐E‐214‐03: Converging Physical and Biological Strategies for Radiation Sensitization of Tumors Using Nanoparticles
Author(s) -
Krishnan S
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3613582
Subject(s) - radiation therapy , molecular imaging , nanoparticle , hyperthermia , materials science , ionizing radiation , cancer research , nanotechnology , biomedical engineering , irradiation , medicine , in vivo , radiology , physics , microbiology and biotechnology , nuclear physics , biology
Radiation therapy is a long‐established component of modern therapy for localized cancers. However, its ultimate utility is limited by the inherent resistance of some cancer cells to ionizing radiation. To circumvent this problem, radiation dose escalation, targeting resistance pathways or resistant cells with novel agents, or image‐guided tumor‐targeted therapy are currently being investigated. Emerging evidence from an explosion of knowledge and research regarding oncologic uses of nanoparticles suggests that unique solutions to each of these problems of radiation resistance can be formulated via the use of metallic nanoparticles. Molecular imaging and image‐guidance may be achieved using fluorescent metallic nanoparticles with size‐tunable narrow emission spectra, long fluorescence half‐lives, and resistance to photobleaching. Bioconjugated nanoparticles can be synthesized, characterized, validated and optimized for excellent spatio‐temporal resolution of tumor‐specific receptor targets. Furthermore, non‐invasive serial quantitative optical molecular imaging of cell surface receptors before and after radiation therapy (and/or targeted therapy) can serve as an early molecular treatment response indicator that guides management decisions. Metallic nanoparticles can be used to augment the efficacy of radiation therapy via physical dose enhancement based on an increase in photoelectric absorption due to the high atomic number (Z) of gold that accumulates preferentially within the tumor due to passive extravasation of nanoparticles through “leaky” tumor vasculature. This radiation dose enhancement can be heightened via biological targeting. Lastly, enhancement of radiation therapy efficacy can be achieved more biologically. Here, extrinsic actuation of tumor‐homing nanoparticles to generate mild temperature hyperthermia enhances vascular perfusion and reduces hypoxia initially and causes vascular disruption subsequently to improve radioresponse. The extrinsic energy source is light for colloidal gold nanoparticles with a large absorption cross section that absorb and scatter light strongly at a characteristic wavelength (their plasmon resonance) and have a high thermal conductivity to couple this heat to the surrounding tissue. Alternatively, the extrinsic energy source may be an alternating magnetic field for super paramagnetic iron oxide nanoparticles. These interfaces between nanotechnology and radiation oncology warrant continued investigation by interdisciplinary teams of physicists, chemists, biologists, clinicians, and engineers in industry and academia. This talk will illustrate some examples of such interactions.