The construction of a soft flash x‐ray (FX) apparatus with a new type of FX tube for biomedical use is described. The FX apparatus may be used for condenser charging voltages of 50–90 kV and peak currents of 20–40 kA. The electric pulse width of the FX waveforms was almost constant and its value was about 0.3 μs. The effective focal spot varied according to the condenser charging voltage, the anode–cathode (A–C) distance, etc., ranging from 0.2–3.0 mm in diameter. We selected two combinations of electrodes: (a) for normal focusing and a high dose rate; (b) for fine focusing and a low dose rate. The FX intensity was determined by the condenser charging voltage and the A–C distance, while the FX quality (average spectrum distribution) was determined by the average voltage of the FX tube and insertion of metal filters. The average voltage of the FX tube varied according to the condenser charging voltage and the A–C gap impedance. Various clear FX images were obtained by controlling the FX intensity, quality, and the focal spot size. We used Fuji Computed Radiography (FCR) in conjunction with our FX radiography, and by controlling the FX quality and the focal spot size, we obtained some interesting biomedical radiograms.

High-intensity flash x-ray apparatus for biomedical radiography

The preparation of highly homogeneous hybrid organic−inorganic materials with enhanced functional properties requires a deep understanding of the synthesis process and a high control of the material structure. To achieve this goal it is necessary to apply advanced characterization techniques that can elucidate all the different features of a structure that is complicated by the presence of interconnected organic and inorganic species that cooperate in the building of a complex hybrid network. We have used as a case study a sol−gel synthesized germania−silica hybrid organic−inorganic material with a content of germania up to 30% in molar concentration with respect to silica. The material has been prepared using 3-glycidoxypropyltrimethoxysilane (GPTMS) as the organically modified alkoxide. Solid-state nuclear magnetic resonance (NMR) spectroscopy, coupled with infrared and Raman spectroscopies, has been used to investigate the structure of the material. In the samples prepared without germania or with a ge...

Structural Control in Germania Hybrid Organic−Inorganic Materials

The flash energy subtraction technique, its principle of operation, and the control methods concerning the FX spectrum distribution are described. This technique was performed by using a high intensity soft flash x-ray (FX) generator having spectrum control functions, Fuji computed radiography (FCR) achieved with a subtraction function, a thin metal filter of copper, and two or three imaging plates. The FX generator was a single exposure type and consisted of the following components: a high voltage generator, a simple low impedance coaxial transmission line with a high voltage coaxial condenser (0.2μF, 100kV), a gas gap switch having a high energy trigger device, a turbo molecular pump, and two types of demountable FX tubes, each of a different type. The FX distribution was controlled to the wide energy latitude from very soft to slightly hard in order to perform the single exposure (flash) energy subtraction radiography. The peak intensity of the FX spectrum rapidly shifted the high photon energy region according to insertion of metal filters. Various single exposure subtraction images were obtained by the subtraction between the soft image (no filter) and the hard image (after filtering).

Flash Energy Subtraction Technique Using a Thin Metal Filter

*1 Department of Physics, School of General Education, Iwate Medical University, 3-16-1 Honcho-dori, Morioka 020, Japan *2 Department of Radiology, School of Medicine, Iwate Medical University *3 Department of Radiology , School of Biomedical Technology, Tohoku University *4 Central Radiation Center, Tohoku University Hospital *5 Fuji Medical System Co., Ltd. *6 Hokuto Machinery Co., Ltd. *7 Konan Hospital

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Flash X-ray Techniques for Biomedical Radiography

Silica−germania thin films are important materials for photonic applications, but synthesis of these films is quite difficult to achieve especially with the task of obtaining a homogeneous structure. We have prepared mesoporous silica−germania films via evaporation-induced self-assembly from ethanolic solutions of Si and Ge chlorides, using a triblock copolymer as the templating agent. The mesostructure has been found to have tetragonal symmetry, and the degree of order decreased with increasing Ge content. X-ray photoelectron spectroscopy has shown that the chemical composition of the films is close to the nominal composition. Infrared analysis has revealed that the pore walls are highly condensed and residual hydroxyls are present as isolated or hydrogen bonded silanols in short chains. UV−vis absorption and photoluminescence spectra have been correlated with the presence of photoactive oxygen-deficient Ge2+ centers which can give rise to a variation in the refractive index upon high-power density UV ir...

Self-Assembled Mesoporous Silica−Germania Films

A pulsed X-ray source and a diffractometer used with this source have been constructed. The pulsed X-ray tube can be driven at a peak voltage of 300 kV and a peak anode current of 5 kA to give X-ray pulses with a duration of about 40 ns at a repetition rate of up to 10 Hz. The high voltage is generated by a Marx generator coupled to a pulse forming line. One X-ray pulse contains about 3×106 Cu Kα photons. Some preliminary observations of the diffraction patterns from an LiF crystal have been made using a multichannel photodiode array as a detector. The use of this apparatus as a time-resolved X-ray diffractometer are discussed in this report.

A Repetitional Pulsed X-Ray Diffractometer System

SiO 2 -GeO 2 glasses have been prepared by the sol-gel method, and Raman scattering, fluorescence and refractive indices have been measured Very broad fluorescence bands due to Ge ions are observed around 530 nm The fluorescence intensity depends on the water content of glass Samples heated to 800 ° C have no fluorescence band in this region We discuss the origin of this fluorescence center as due to the defect structure of the dangling bond between Ge and O ions

Optical properties of SiO2-GeO2 glasses made by sol-gel method

Diffuse phase transition in 0.3 wt.% PI3+ doped Sr0.6Ba0.4Nb2O6 crystal near T c = 65°C is carefully examined by X-ray diffraction technique to clarify the nature of the transition. The Bragg intensity of the (0 0 4) reflection decreases gradually with increasing temperature. The diffuse intensity around the (0 0 4) reflection has a broad maximum near T c and a strong anisotropic distribution. These results analysed in terms of the piezoelectric coupling between the local strain increased by the impurity and the polarization.

Kanji Kubota

Papers

A Repetitional Pulsed X-Ray Diffractometer System

Optical properties of SiO2-GeO2 glasses made by sol-gel method

X-ray study on the diffuse transition in 0.3 wt.% pr3+ doped sr0.6ba0.4nb2o6 crystal