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The purpose of this study is to test the hypothesis that gold nanoparticle (AuNP, nanogold)-enhanced radiation therapy (nanogold radiation therapy, NRT) is efficacious when treating the radiation resistant and highly aggressive mouse head and neck squamous cell carcinoma model, SCCVII, and to identify parameters influencing the efficacy of NRT. Subcutaneous (sc) SCCVII leg tumors in mice were irradiated with x-rays at the Brookhaven National Laboratory (BNL) National Synchrotron Light Source (NSLS) with and without prior intravenous (iv) administration of AuNPs. Variables studied included radiation dose, beam energy, temporal fractionation and hyperthermia. AuNP-mediated NRT was shown to be effective for the sc SCCVII model. AuNPs were more effective at 42 Gy than at 30 Gy (both at 68 keV median beam energy) compared to controls without gold. Similarly, at 157 keV median beam energy, 50.6 Gy NRT was more effective than 44 Gy NRT. At the same radiation dose ( approximately 42 Gy), 68 keV was more effective than 157 keV. Hyperthermia and radiation therapy (RT) were synergistic and AuNPs enhanced this synergy, thereby further reducing TCD50 s (tumor control dose 50%) and increasing long-term survivals. It is concluded that gold nanoparticles enhance the radiation therapy of a radioresistant mouse squamous cell carcinoma. The data show that radiation dose, energy and hyperthermia influence efficacy and better define the potential utility of gold nanoparticles for cancer x-ray therapy. Phys Med Biol

OBJECTIVE: Normal tissues, including the central nervous system, tolerate single exposures to narrow planes of synchrotron-generated x-rays (microplanar beams; microbeams) up to several hundred Gy. The repairs apparently involve the microvasculature and the glial system. We evaluate a hypothesis on the involvement of bystander effects in these repairs. METHODS: Confluent cultures of bovine aortic endothelial cells were irradiated with three parallel 27-microm microbeams at 24 Gy. Rats' spinal cords were transaxially irradiated with a single microplanar beam, 270 microm thick, at 750 Gy; the dose distribution in tissue was calculated. RESULTS: Within 6 hours following irradiation of the cell culture the hit cells died, apparently by apoptosis, were lost, and the confluency was maintained. The spinal cord study revealed a loss of oligodendrocytes, astrocytes, and myelin in 2 weeks, but by 3 months repopulation and remyelination was nearly complete. Monte Carlo simulations showed that the microbeam dose fell from the peak's 80% to 20% in 9 microm. CONCLUSIONS: In both studies the repair processes could have involved "beneficial" bystander effects leading to tissue restoration, most likely through the release of growth factors, such as cytokines, and the initiation of cell-signaling cascades. In cell culture these events could have promoted fast disappearance of the hit cells and fast structural response of the surviving neighboring cells, while in the spinal cord study similar events could have been promoting angiogenesis to replace damaged capillary blood vessels, and proliferation, migration, and differentiation of the progenitor glial cells to produce new, mature, and functional glial cells. Exp Hematol

Diffraction enhanced imaging is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron which produces images of thick absorbing objects that are almost completely free of scatter. They show dramatically improved contrast over standard imaging applied to the same phantom. The contrast is based not only on attenuation but also the refraction and diffraction properties of the sample. This imaging method may improve image quality for medical applications, industrial radiography for non-destructive testing and x-ray computed tomography.