Irradiation Device Research Articles

Environmental remediation by an integrated microwave/UV-illumination method II.: Characteristics of a novel UV–VIS–microwave integrated irradiation device in photodegradation processes

In this brief article we examined the characteristics of a novel UV–VIS–microwave integrated irradiation device and explore its usefulness using the now well-established photo-degradation of a cationic dye (rhodamine-B; RhB) as a test substrate. The device consisted of a double quartz cylindrical plasma photoreactor (DQCPP) equipped with a microwave (MW) powered electrodeless Hg/Ne irradiation source. The latter is activated only by the MW radiation. The integrated MW–UV–VIS radiations so produced and incident on the DQCPP reactor significantly enhanced the decomposition of the RhB dye through simultaneous photocatalytic and photosensitization processes.

Optimization of the diameter of a radial irradiation device for photodynamic therapy in the esophagus.

Photodynamic therapy (PDT) is a local therapeutic technique based on the photosensitization of lesions using a dye prior to light-induced tissue destruction. PDT of intraepithelial neoplasia in Barrett's esophagus, or of early squamous-cell carcinoma of the esophagus, requires light application devices that allow homogeneous and well-defined illumination of the tissue surface. Such devices must be large enough to induce complete unfolding of the esophagus in spite of esophageal motility and elasticity. The aim of this study was therefore to determine the optimal diameter of a cylindrical illumination device for PDT in this organ. The study included nine patients (aged 49-72 years) who underwent panendoscopy. Flexible transparent hollow tubes with diameters ranging from 13 to 19 mm were successively introduced into the esophagus, and the esophageal wall was viewed from the inside through the tube using a flexible small-diameter endoscope. The number of folds was counted. Observations of the upper, middle, and lower thirds of the esophagus were recorded. The radial location of the folds was also recorded, and defined as follows: anterior wall (up), posterior wall (down), side walls (right, left). No significant difference in the number of folds between the lower and middle parts of the esophagus was noticed. However, the upper third had significantly fewer folds (about 30 %) than the other two parts. For diameters above 17 mm, this difference was less dramatic. The number of such folds was shown to decrease with the increasing diameter of the device. It appears that 18 mm or more is the optimal diameter for a fixed-geometry cylindrical photodynamic therapy irradiating device for the patient category considered in this study. It was also observed that most folds were located on the side walls of the esophagus.

Algorithm for controlling a mobile irradiation device with a circular symmetric light distribution for plant lighting

Algorithm for controlling a mobile irradiation device with a circular symmetric light distribution for plant lighting

Accuracy of dynamic multileaf position and influence of beam profile according to change in dose monitor unit in QA plan of intensity modulated radiotherapy

The number of dose monitor units in IMRT QA plans differs form the actual conditions of IMRT in dosimetry for verification of dynamic multileaf-IMRT (DMLC-IMRT). We measured the accuracy of the position of the dynamic multileaf collimator and the dose profile for various numbers of dose monitor units, and verified the accuracy of dosimetry in an IMRT QA plan. The accuracy of the position of the dynamic multileaf collimator was measured by using the software of the external irradiation device, and the dose profile was measured by using the semiconductor profiler. Deviation in the position of the dynamic multileaf collimator increased as the number of dose monitor units decreased. When deviation in the position of the dynamic multileaf collimator was large and the gap width of the multileaf collimator was narrow, the change in dose profile was large. Therefore, verification of IMRT QA plans requires a phantom and measurement device close to the actual conditions of IMRT.

An automated irradiation device for use in cyclotrons

Two cyclotrons are being operated at IPEN-CNEN/SP: one model CV-28, capable of accelerating protons with energies up to 24 MeV and beam currents up to 30 mA, and three other particles; the other one, model Cyclone 30, accelerates protons with energy of 30 MeV and currents up to 350 mA. Both have the objective of irradiating targets both for radioisotope production for use in nuclear medicine and general research. The development of irradiating systems completely automatized was the objective of this work, always aiming to reduce the radiation exposition dose to the workers and to increase the reliability of use of these systems.

In situ characterization of a small sized motor under neutron irradiation

In order to conduct the integrated irradiation experiment of fusion blanket with testing reactor, it is indispensable to develop a small motor with high radiation resistance as the irradiation device. Therefore, the small motor was irradiated at the Japan Materials Testing Reactor. From this result of the irradiation test of a small motor, it became clear that the small motor was rotating normally up to the gamma-ray dose of 3.1×10 7 Gy, the fast neutron fluence of 2.8×10 20 n/m 2 and the thermal neutron fluence of 5.2×10 21 n/m 2 at 50 °C. The conductor resistance and the insulation resistance of polyimide coated wire, which did not change until the total gamma-ray dose of 3.1×10 8 Gy, the fast neutron fluence of 2.8×10 21 n/m 2 and the thermal neutron fluence of 5.2×10 22 n/m 2 at 50 °C, were 12 Ω and 1×10 8 Ω, respectively.

A stereotactic device for experimental rat and mouse irradiation using gamma knife model B--technical note.

For radiobiological experiments using the Gamma Knife model B, we constructed a stereotactic device to irradiate rat and mouse brains and verify the absorbed dose at the target using thermoluminescence dosimetry and a head phantom. Our stereotactic device is primarily designed for rats using the fixation principles of a stereotactic atlas. A head-fixation adapter for a mouse was constructed to enable targeted irradiation of mouse brains. We built simple phantoms to simulate rat and mouse heads. We placed thermoluminescent dosimeters at various positions on the phantom for dose measurements. Dose planning employed the Leksell Gamma Plan version 4.11 software, assuming a spherical skull geometry for all calculations. The measurements demonstrated that the actual absorbed dose agreed with our calculations within the errors of thermoluminescence dosimetry and the accuracy of our irradiation technique and dose calculations. This device provides an accurate method for irradiating rat and mouse brains using the Gamma Knife model B.

Erosion of carbon materials under high fluxes

Experimental results of graphite erosion under high fluxes by using a high flux irradiation device in Osaka University are reviewed. Results of chemical sputtering experiments by 5 keV D3+ beams with fluxes from 0.5 × 1021 to 3.9 × 1021 D/m2 s showed an increase in peak temperatures from 900 K to 980 K with flux for isotropic graphite and CFC. These peak temperatures are higher than those of low flux results (750 K-850 K, ≤ 1020 m-2 s-1). The peak yields did not show clear flux dependence. Results of radiation-enhanced sublimation (RES) experiments by 5 keV Ar+ beams with fluxes from 3.5 × 1019 to 1.5 × 1021 Ar/m2 s showed a significant decrease in the RES yields with flux for isotropic graphite and pyrolytic graphite. The flux dependence of the RES yields (total yields minus physical sputtering yields) was about ϕ-0.26 (ϕ: flux), while the flux dependence in fluxes from ∼1017 to ∼1019 Ar/m2 s was about ϕ-0.07. Comparison between models and experiments for chemical sputtering and RES are also shown.

Design of an in-pile device for testing of WCLL double wall tubes

The present paper describes irradiation devices proposed by SCK CEN to test segments of water cooled lithium–lead blankets (WCLL), and in particular their double-wall tubes (DWT), under irradiation in the BR2 reactor. The purpose of the first experiment is to assess the efficiency of a tritium permeation barrier (TPB) coating at the outer surface of the DWT. Hence, two DWT segments are plunged in a lithium–lead pool. The inside of the DWT is flushed by helium and collects the tritium permeating through the wall. One of the DWTs has received a TPB coating, the other not, so that comparative measurements are possible. For the second experiment, a DWT segment is heated by the gamma flux of BR2 and cooled at the inside by pressurised water. Hence, the temperature gradient tends to separate the two tubes. The purpose is to verify how the brazing agent performs at doses up to 3 dpa. The irradiation device is installed inside the central hole of a BR2 fuel element, in order to maximise the fast neutron component of the flux received by the target. As an attractive alternative, the utilisation of the PWR loop Callisto is also proposed.

Print Quality with Hot Roller and IR-Radiation Fixing Methods

In electrophotographic office printing hot roller fusing is favored, whereas non-contact fixing methods are used especially in web printing. The aim of this study was to find out whether there are differences in quality and in the quality-forming characteristics between contact and non-contact fixing, and if so, what the reasons might be. The research was prompted by proliferation of web fed color printers for publishing applications. For the study an IR fixing installation with ceramic plates was built. Unfused print areas were obtained from a desktop color laser printer and fixed with a detached hot roller fuser, the IR radiation device and with a combination of these two. The fixing energy was varied by alteration of the temperature. In addition to basic quality measurements, the micro scale quality was measured with a multigeometrical optical testing device that was developed in our laboratory. The data on adhesion, toner coverage, density, gloss, small scale density and gloss variation, tangential edge profile and point spreading clearly proved that the surfaces are formed differently in the two fusing methods. Variation of energy in fusing also turned out to have a different impact. In hybrid fixing, the first phase determines the final outcome. This article presents a summary of the data and discusses the results from the viewpoint of fixing mechanisms.

Monte Carlo calculation of gamma spectra inside a hollow lead cylinder / Berechnung von Gammaspektren im Innern eines Hohlzylinders aus Blei mit Hilfe der Monte-Carlo-Methode

In a previous work, a simulation study to investigate the enhancement of the fast neutron flux inside a hollow lead cylinder located near the core of a pool type reactor has been carried out. In this complementary work, the calculation of gamma radiation spectra inside the same irradiation device was performed using the MCNP code. Two radiation spectra were considered as input sources: a typical fission gamma spectrum in a nuclear reactor, for the calculation of the socalled fission γ spectrum inside the device; and a fission neutron spectrum, for the calculation of the (n, γ) spectrum. The calculation was made considering two diffusing media adjacent to the reactor core: water and beryllium + water. The lead wall thickness, t, adopted for the hollow lead cylinder ranges from 2 to 10 cm. In order to compare the results with and without the irradiation device, reference cases (t = 0) have also been considered. The values of the attenuation factors F att (fission γ fluence) and F att [(n, γ) fluence] are presented. These results, together with those from the previous work, allow an optimisation of the irradiation conditions in order to maximise the absorbed dose due to fast neutrons.

Development of an up-flow irradiation device for electron beam wastewater treatment

Abstract Electron beam irradiation processing is an available technology to treat sludge, groundwater, surface water and industrial and municipal wastewater. The use of this technology into environmental areas has moved slowly because industry and government are always conservative in the adoption of new processes, especially when they can not observe the efficiency and cost effectiveness of a treatment in a full scale facility. In this direction the hydraulic system where the water is presented to the electron beam governs the efficacy of this technology. The present work is based on the development of the irradiation device, an up-flow delivery system that alleviates the dependence of energy transfer to the stream with the beam accelerating voltage (penetration capability). In this work a series of experiments were performed to establish the relationships between accelerating voltage ranging from 0.5 to 1.5 MeV, current, water flow and deposited dose in order to optimize the operating parameters and the selection of a cost-effective commercial electron beam.

Biological effects of millimeter wave irradiation on mice-preliminary results

Millimeter waves at 60 GHz are suitable for discreet radio contact in restricted area, especially for indoor high rate communications. Such wave exposures have not been reported. That is the reason why a study of possible biological effects upon living beings was required. An experimental irradiation device was calibrated and used to irradiate mice. Specific absorption rate and internal fields have been computed for a mouse irradiated at 60 GHz. The measured power flux in free space at the irradiation area is close to 0.5 mW/cm/sup 2/, this probably produces some subtle biological effects. To look for possible biological effects, the authors exposed DBA2 mice grafted either with L1210 cells or with Lewis tumor cells and healthy Swiss mice. There were four obvious observations: there is an individual sensitiveness to 60 GHz waves; the survival of mice grafted with L1210 cells could be increased; the growth of Lewis tumor was enhanced; and the activity of Swiss mice was increased. In any way, those effects have to be taken into account, and the authors suggest prudence before using a 60-GHz waves for indoor communications.

Monte Carlo calculatıon of fast neutron spectra inside a lead hollow cylinder / Berechnung der Spektren schneller Neutronen im Innern eines Hohlzylinders aus Blei mit Hilfe der Monte-Carlo- Methode

A simulation study was carried out in order to investigate the enhancement of the fast neutron spectra in a sample irradiated near the core qf a pool type nuclear reactor. The irradiation device consisted of a lead hollow cylinder where a thin aluminium sample holder containing the sample to be irradiated is placed. Calculations were performed considering water or beryllium + water between the simulated fission neutron source and the irradiation device; the thickness of the wall of the lead cylinder was varied up to 10 cm. The fast neutron spectra in the sample position were calculated and the average fast neutron energy, the total neutron fluence. Φ(E>0.1 MeV), the fast neutron fluence, Φ(E>1 MeV), and the conversion factor, C = Φ/Φ, were determined. It was found that the lead cylinder surrounding the sample induces an appreciable enhancement of the fast neutron spectra. This effect can be described using a gain factor defined, at each point, as the ratio between the fast neutron fluences with and without the irradiation device, G =Φ/Φ(t =0). The gain of the neutron fluence increases from 2 to 4.5 when the lead thickness varies between 2 and 10 cm.

Device for UV irradiation of blood with a disposable blood flow system

A device for extracorporal irradiation of blood by UV light with λ=300–400 nm is described. A disposable blood flow system with a specially profiled polymer cuvette is proposed. Mixing of blood during irradiation ensures uniform irradiation of blood cells passing through the cuvette, which makes it possible to enhance the healing effect of the procedure.

Green light is effective and less painful than red light in photodynamic therapy of facial solar keratoses.

Photodynamic therapy (PDT) with topically applied delta-aminolevulinic acid (ALA) is increasingly employed to treat patients with multiple solar keratoses and superficial skin tumors. For these indications, ALA-PDT has been shown to be highly efficient. Treatment of multiple or extended lesions, however, is substantially hampered by the fact that ALA-PDT is associated with burning pain during the irradiation procedure. The standard irradiation devices commonly used for ALA-PDT emit red light around 630 nm. In the present half-side comparison study we have observed that ALA-PDT employing a green light irradiation device (543-548 nm) is equally effective, as compared with standard red light ALA-PDT. In contrast to red light ALA-PDT, however, green light ALA-PDT caused only little tingling and burning but no pain. These observations indicate that green light ALA-PDT is superior to standard ALA-PDT, because it is associated with less unwanted side effects.

Angular response of electrochemically etched CR-39 to protons of 131 to 925 KeV

Solid state nuclear track detectors (SSNTDs) are widely used in fast neutron dosimetry. Latent tracks formed by slowed-down protons resulting from (n,p)-scattering are usually visualized by electrochemical etching (ECE). To estimate the detection efficiency of a SSNTD the proton response and the etching parameters are required. An irradiation device for angular and energy-dependent irradiations using Rutherford backscattering has been constructed. The CR-39 detectors were irradiated with monoenergetic and parallel protons from 131 to 925 keV at 11 different angles of incidence. The critical angle of incidence to protons for a two-step ECE process is presented.

A New Expression for Determination of Fluences from a Spherical Moderator Neutron Source for the Calibration of Spherical Neutron Measuring Devices

A new expression modifying the inverse square law for determination of neutron fluences from spherical moderator neutron sources is reported. The formalism is based on the neutron fluence at a point outside the moderator as the summation of fluxes of two groups of neutrons: direct neutrons from the central region of the moderator, and moderated neutrons which, to a first approximation, are scattered from the outermost layers of the spherical moderator. The expression has been further developed for spherical neutron measuring devices with an appropriate geometry factor which corrects the reading of the device for non-uniform irradiation of the detector. The combination of the new fluence function and those of the air and room scattered components introduce a calibration model. The fluence relationship obtained for moderated sources may conveniently be used for calculating the more rapid change of neutron dose at close distances than that which is based on the inverse square dependence.

組織表面温制御下YAGレーザー照射治療法の開発

組織表面温制御下YAGレーザー照射治療法の開発

Irradiation devices and irradiation programmes at the high flux reactor (HFR) Petten for the investigation of the irradiation behaviour of stainless steels

Irradiation testing of stainless steels represents an important share in the utilization spectrum of the high flux reactor (HFR) Petten. These tests address in particular austenitic and martensitic steels for thermo-nuclear fusion reactors, austenitic steels for fast breeder reactors, and stainless steels and CrNi-alloys for light water reactors. A number of well-proven irradiation devices covering an extensive range of applications and operated by a vastly experienced group are available at the HFR. In addition, at the Petten hot cells, many diversified tools exist for irradiation testing of stainless steel. The irradiation devices are tailored to provide typical, reactor specific environment conditions to the samples. Such conditions are maintained within narrow specifications. In this respect, the long lasting operational experience originating from the many materials irradiation programmes performed at the HFR, the high and consistent availability of the HFR and its reliability with regard to provision of predictable and reproducible irradiation conditions, are the keys to these many demonstrable experiments. The adjustment of typical neutron spectrum at the irradiation samples is performed through an appropriate choice of structural materials and their arrangement within the irradiation device. Many irradiation devices are reloadable, being specially suited for intermediate unloading and hot cell measurement of the irradiated samples. Other devices are equipped with integral loading and measuring systems for in-pile measurement of characteristic irradiation parameters (e.g. the creep behaviour). The neutron fluence is calculated and then measured after irradiation from neutron fluence monitor sets which are integrated into the sample carriers. The post irradiation examination and testing of the irradiated samples is performed either at the customer's hot cells or at the Petten hot cells, in particular, when intermediate measurements are required. Dedicated and specialized testing equipment for tensile, creep, Charpy, fatigue and crack propagation testing, various microscopy systems (SEM, TEM) and other test equipment (gamma-scanning, chemical analysis, image analysis, etc.) are all available at the Petten hot cells.