Sn Filter Research Articles

蛍光ガラス線量計小型素子システムにおける素子タイプ別エネルギー依存性と線量補正の検討

We studied energy characteristics and examined dose correction when using a radiophotoluminescence glass dosimeter (GD). There are two types of GD. One type of GD is called GD-352, which consists of a glass element and Sn filter. Another type of GD is called GD-302, which has no additional filter. Energy characteristics of these two types of GDs were investigated using a diagnostic X-ray energy range. The equation is as follows: Cf (correction factor) = average of GD measured value/air kerma. The compensation formula for estimating air kerma with each X-ray energy was determined from an approximation formula based on the ratio between GD system reading and air kerma with a specific X-ray energy. From compensation results obtained using the formula, the error for air kerma using GD-352 was approximately 0%, and the error using GD-302 was about 1.0%.

Chirp of the single attosecond pulse generated by a polarization gating

The chirp of the xuv supercontinuum generated by a polarization gating is investigated by comparing three-dimensional nonadiabatic numerical simulations with classical calculations. The origin of the chirp is the dependence of the energy gain by an electron on the return time. The chirp is positive and its value is almost the same as that when a linearly polarized laser is used. Although the $250\text{\ensuremath{-}}\mathrm{eV}$-wide supercontinuum corresponds to a single attosecond pulse, the shortest duration of the pulse is limited by the chirp. By compensating the positive chirp with the negative group velocity dispersion of a Sn filter, it is predicted that a single $58\text{\ensuremath{-}}\mathrm{as}$ pulse can be generated.

Ceramic foams porous microstructure characterization by X-ray microtomography

Knowledge of the porous structure of amorphous materials is of fundamental importance in calculating geometrical parameters such as total porosity, pore size distribution and physical parameters relating to fluid flow inside void space. The present work deals with the measurement of the microstructural parameters of porous ceramic filters. Microtomographic measurements of samples were taken using an X-ray tube. Bremsstrahlung radiation was filtered in transmission mode with a Sn filter at 58.5 and 28.3 keV and the images analyzed in two ways. The first method consisted in analyzing transepts of the images in order to calculate total porosity based on the average particle size and media linear attenuation coefficients. The second method involved a study of the images using an image analysis software, called Imago, which allows one to calculate total porosity and pore size distribution. The total measured porosity of the filter C90 was 73.8%, 71.1%, 74.4% and 71.5% by, respectively, the Arquimedes method, simple gamma ray transmission, transept analysis and analysis of the microtomographic images at 28.3 keV.

Patient dose measurement with fluorescent glass dosimeter: characteristics evaluation and patient skin dose measurement in abdominal interventional radiology

In this study, we investigated the usefulness of the fluorescent glass dosimeter for measuring patient dose. The fluorescent glass dosimeter is constructed of a glass element and its holder. One type has a tin (Sn) filter and the other does not. The characteristics of these two types of fluorescent glass dosimeters were studied in the range of diagnostic X-ray energy. The result was excellent for each characteristic. Directional dependency, however, was recognized in the fluorescent glass dosimeter with tin (Sn) filter. Based on these evaluations, patient skin dose was measured for abdominal interventional radiology and diagnostic digital subtraction angiography using the holder without filter, which is less direction-dependent and eliminates obstructive shadows in radiography and fluoroscopy. The average skin dose of 30 patients for abdominal IVR was 1.17+/-0.44 Gy (0.51-1.94 Gy), while those for diagnostic DSA examination was 0.54+/-0.21 Gy (0.15-1.02 Gy). The fluorescent glass dosimeter provides high capability for skin dose measurement. The fluorescent glass dosimeter is also useful for controlling patient dose during IVR procedures.

Determination of captafol, cyhexatin, 1-naphthylacetic acid and quintozene in apple, Japanese pear and melon by simultaneous extraction

A simple and rapid method is described for the determination of the non-registered pesticides, captafol, quintozene (PCNB), cyhexatin and 1-naphthylacetic acid (NAA), in fruits. These pesticides were extracted with acidified acetone, then captafol and PCNB were purified with a Florisil mini column and analyzed by GC-ECD. Cyhexatin was ethylated with ethylmagnesium bromide, and the ethyl derivative was analyzed by GC-FPD (Sn filter). NAA was purified with liquid-liquid extraction and determined by HPLC equipped with a fluorescence detector. These analytes were identified with GC/MS or LC/MS. The minimum identified concentration of the pesticides was below 0.2 ng per injection, which corresponds to a detection limit of below 0.02 microgram/g in the original samples. Recoveries of the pesticides spiked at 0.1 microgram/g into apple, Japanese pear and melon were greater than 61%.

Characterization of porous microstructure by x‐ray microtomography

AbstractKnowledge of the porous structure of amorphous material is of fundamental importance in calculating geometric parameters such as total porosity, pore size distribution and physical parameters related to fluid flow inside void space. This work involved the measurement of microstructural parameters of petroleum reservoir rocks and porous ceramic filters. Microtomographic measurements of samples were performed by employing an x‐ray tube. Bremsstrahlung radiation was filtered in transmission mode with an Sn filter at 58.5 and 28.3 keV. The beam width was about 80 µm at the sample position center. Images were analyzed in two ways. In the first method, transepts of the images were analyzed in order to calculate the total porosity by means of the average particle and media linear attenuation coefficients. In the second method, images were studied using image analysis software, named Imago, allowing the calculation of total porosity and pore size distribution. The total measured porosity of the filter C90 was 73.8, 71.1, 74.4 and 71.5% using the Archimedes method, simple gamma‐ray transmission, transept and image analysis of the microtomography at 28.3 keV, respectively. Measured total porosity for one of the sandstones was 23.23, 24.70, 23.43, 29.68, 29.65 and 27.80% using Hg and gas porosimetry, the Archimedes method, simple gamma‐ray transmission and transept analysis of the microtomography at 58.5 and 28.2 keV, respectively. Copyright © 2002 John Wiley & Sons, Ltd.

Basic study of one-shot dual energy subtraction sialography: Evaluation method of optimal conditions

The author produced a bone-iodine step (BI-step) phantom and performed a basic experiment using it in one-shot dual energy subtraction sialography by computed radiography (CR). There are many parameters of energy subtraction such as the tube voltage, filter, Imaging Plate (IP), grid, contrast medium, and image processing. In this study, the author evaluated the influence of tube voltage (50 ∼100 kVp), copper (Cu) and tin (Sn) filters, and the iodinated contrast medium on the resultant image. The conditions of optimal subtraction were theoretically determined, and the separation between bone and iodine reached a maximum at a tube voltage of 50kVp with a Cu-filter of 0.8 mm in this investigation. The correctness of these conditions were confirmed on actual subtraction images. These results appear to be applicable to digital subtraction sialography following a further combination with the other parameters.

Self-dose and cosmic-ray dose of CaSO4:Tm (UD-200S) dosimeter.

Measurement was made to determine self-dose at Mihoro Dam Tunnel where cosmic-ray was fairly attenuated. The dosimeter with Pb and Sn filter had the same self-dose of 0.26 nCkg-1 h-1 as that without the filter. Our experiment shows that self-dose is due to any traces of natural radioactivity in the phosphor and the packaging. Cosmic-ray dose was evaluated 0.74 nC kg-1h-1 from our experiment at sea surface, and this value was somewhat smaller than the cosmic-ray intensity in Japan. The reason is considered to be low TL response for cosmic-ray hard component.

Optical image formation with a Fresnel zone plate using vacuum-ultraviolet radiation*

A self-supporting Fresnel zone plate with empty transparent zones has been used to focus vacuum-ultraviolet (vuv) radiation with wavelengths as short as 565 A. The radiation was produced by two broad-band sources, (i) the molecular continuum of a helium gas-discharge lamp, which extends from 600 to 1100 A with a broad peak at 810 A, and (ii) the synchrotron continuum of an electron storage ring filtered by a Sn filter, which extends from 520 to 750 A with a broad peak at 565 A. The zone plate was used as a simple converging lens to form an optical image of an object mesh on a sodium salicylate film, where it was photographically recorded. Magnifications of 20× and linear resolutions within an order of magnitude of the theoretical resolution limit of the zone plate were obtained. Applications of this device as a vuv microscope are discussed.

Calibration of monitoring films for the dosimetry of gamma rays by means of low-activity 226Ra- or 137Cs-sources in a shielded transportable facility

When persons are irradiated by X or gamma rays, the accurate evaluation of the exposure by means of film dosimetry depends greatly upon the establishment of correct density-exposure calibration curves. The delicate procedure of calibration of film badges is made easy by a shielded and transportable facility which uses either a 226Ra- or a 137Cs-calibration source, both sources being a low activity. The facility comprises a stand for nine film badges at fixed places, permitting exposures from 50 to 1500 mR in about 11 hr with the 226Ra-source and in about 9 hr with the 137Cs-source. The density-exposure curves obtained under “scatter-free” conditions were compared to those obtained in the facility. This comparison showed that the scattered radiation, due essentially to the lead shield around the source, is almost completely absorbed by a Sn filter (1 mm Sn for the 226Ra-source, 0·1 mm Sn for the 137Cs-source) covering one part of the film badge on both sides. The density produced under the Sn filter for a given exposure in the facility is higher by 10 per cent than that produced under the Sn filter by the same exposure delivered under “scatter-free” conditions of irradiation. Thus, when the exposure of a film badge worn by a person is interpreted by comparison with a calibration film irradiated in the facility, the deduced exposure is about 10 per cent lower than when the film badge is interpreted by comparison with a calibration film irradiated under “scatter-free” conditions. If correction factors are applied with the described calibration facility, it is possible to obtain results comparable to those obtained under “scatter-free” conditions. The log D = ƒ( log X) curves and equations, as well as the correction factors, make it possible to dispense with the “scatter-free” calibration.

Effect of Environmental Scatter on Film Badge Readings

Film badges, which had portions filtered both sides by Al, Sn and Cd filters, as well as an unfiltered portion, were exposed around isolated γ-ray sources (226Ra, 60Co and 137Cs). The effect of a large unit-density plastic sheet at various distances beneath the films was investigated. Increased blackening representing apparent increased γ-ray dose of up to 40% occurred mainly on the unfiltered portion of the film, due to lower-energy scattered radiation and to secondary electrons from the sheet when it was closer than about 15 cm to the films. Increased blackening when body phantoms were placed immediately behind the films was small, but not negligible.

フィルムおよび銀活性化ガラスの熱中性子感度と,それらによる熱中性子,γ線混合場における測定

The thermal neutron responses of the film (Fuji Badge Film III, Type A) and the silver-activated phosphate glass (8×8×4.7 mm) which has the composition of Li-Al-B-Ag were measured. Thermal neutron exposure was made in the hole No.7 (thermal column) of JRR-1 (Water Boiler Type, 50 kW) in JAERI. The thermal neutron flux was measured by the activation of gold foils. Cd and Sn filter combination and B2O3 were used to differentiate thermal neutron and γ rays. The thermal neutron responses of film and glass in Equivalent Ra dose were (3.84±0.77)×10-10 rads/ncm-2 and (4.14±0.46)×10-9 rads/ncm-2 respectively. Capture γ ray emission of 1 mm Cd was determined to be (1.50±0.30)×10-9 rads/ncm-2 and (1.62±0.17)×10-9 rads/ncm-2 by film and glass measurements respectively, and agreed well with the calculated value of 1.2×10-9 rads/ncm-2 as the lower limit.The practical method of determination of thermal neutron and γ ray dose in the mixed radiation fields was presented when film or glass are used as the personnel monitoring dosimeters.