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Yuki Yoshimatsu, 1, 2 Kazunori Tobino, 1, 3 Shinsuke Nagami, 4 Naomi Yagi, 2, 5, 6 Yoshitaka Oku 2 1Department of Respiratory Medicine, Iizuka Hospital, Iizuka, Fukuoka, Japan; 2Department of Physiology, Hyogo College of Medicine, Nishinomiya, Hyogo, Japan; 3Department of Respiratory Medicine, Juntendo University Graduate School of Medicine, Tokyo, Japan; 4Department of Speech Language Pathology and Audiology, Faculty of Rehabilitation, Kawasaki University of Medical Welfare, Kurashiki, Okayama, Japan; 5Department of Neurology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; 6Department of Medical Engineering, Himeji Dokkyo University, Himeji, Hyogo, JapanCorrespondence: Yuki YoshimatsuDepartment of Respiratory Medicine, Iizuka Hospital, Iizuka, Fukuoka 820-8505, JapanTel +81-948-22-3800Fax +81-948-29-5744Email yukitsukihana0105@gmail.comIntroduction: Dysphagia is a newly acknowledged multifactorial risk factor for the exacerbation of chronic obstructive pulmonary disease (COPD). Effective screening methods are awaited. We performed a prospective study to evaluate the impact of musculature and breathing–swallowing discoordination on the exacerbation of COPD with a novel swallowing monitor using a piezoelectric sensor.Patients and Methods: This was the second part of a prospective study of patients with COPD from the Iizuka COPD cohort. Seventy patients with stable COPD underwent dysphagia screening, skeletal muscle mass index (SMI) and tongue pressure measurements, and swallowed 3 mL and 30 mL of water while wearing a swallowing monitor. Patients were followed for one year.Results: During the follow-up period, 28 patients experienced exacerbations (E group), and 42 had none (non-E group). There was no significant difference in tongue pressure measurements between the two groups. The SMI in the E group was significantly lower than that in the non-E group. Among the swallowing monitor measurements, the 3 mL I-SW% (the percentage of swallows in which inspiration preceded the swallow [out of ten 3 mL swallows]) was significantly lower in the E group than in the non-E group.Conclusion: Breathing–swallowing coordination is an independent factor related to the exacerbation of COPD. Not only the presence of discoordination but also the inability to produce an airway protection mechanism may contribute to more frequent aspiration and exacerbations.Keywords: dysphagia, screening, aspiration, piezomonitor, inspiration, COPD

Wan Nordiana Rahman,1,2 Stéphanie Corde,3,4 Naoto Yagi,5 Siti Aishah Abdul Aziz,1 Nathan Annabell,2 Moshi Geso21School of Health Sciences, Universiti Sains Malaysia, Kelantan, Malaysia; 2Division of Medical Radiation, School of Medical Sciences, Royal Melbourne Institute of Technology, Bundoora, VIC, 3Radiation Oncology, Prince of Wales Hospital, High Street, Randwick, 4Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia; 5Japanese Synchrotron Radiation Research Institute, Sayo-gun, Hyogo, JapanAbstract: Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z) and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. In this research, synchrotron-generated monoenergetic X-rays in the 30–100 keV range were used to investigate the energy dependence of radiosensitization by gold nanoparticles and also to determine the photon energy that produces optimum effects. This investigation was conducted using cells in culture to measure dose enhancement. Bovine aortic endothelial cells with and without gold nanoparticles were irradiated with X-rays at energies of 30, 40, 50, 60, 70, 81, and 100 keV. Trypan blue exclusion assays were performed after irradiation to determine cell viability. Cell radiosensitivity enhancement was indicated by the dose enhancement factor which was found to be maximum at 40 keV with a value of 3.47. The dose enhancement factor obtained at other energy levels followed the same direction as the theoretical calculations based on the ratio of the mass energy absorption coefficients of gold and water. This experimental evidence shows that the radiosensitization effect of gold nanoparticles varies with photon energy as predicted from theoretical calculations. However, prediction based on theoretical assumptions is sometimes difficult due to the complexity of biological systems, so further study at the cellular level is required to fully characterize the effects of gold nanoparticles with ionizing radiation.Keywords: gold nanoparticles, radiotherapy, monoenergetic synchrotron radiation, radiosensitizers, in vitro

Knowledge of electron densities for materials is important for treatment planning for proton and heavier-ion radiotherapy. In order to obtain the electron densities with high precision, we have developed dual-energy X-ray computed tomography using synchrotron radiation. Two monochromatic X-rays with different energies generated from synchrotron radiation enables tomographic imaging which produces a cross sectional image based on electron density plus an additional image based on effective atomic number. Experiments for the dual-energy X-ray CT were made on the BL20B2 beamline at SPring-8. An image intensifier system and a CCD camera were used as the 2-D detectors. The measured electron densities were agreement to within 2% of the theoretical ones. Electron density and effective atomic number provide different contrast in images. Dual-energy X-ray CT can be used for quantitative measurement of the material. Index Terms--Computed tomography, effective atomic number, electron density, monochromatic X-ray.