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Resumen Introduccion y objetivos En la obtencion de imagenes de angiografia por cardiotomografia (ACT) es importante escoger una ubicacion adecuada para inyectar el medio de contraste (p. ej., el brazo o la pierna) a fin de evitar la formacion de artefactos que este provoca. En este estudio se comparan los valores de tomografia computarizada (TC) y las puntuaciones de visualizacion de las imagenes tridimensionales (3 D) de los lumenes de los vasos sanguineos del brazo y la pierna durante la ACT en pacientes neonatos y lactantes. Pacientes o materiales y metodos Entre los meses de enero de 2017 y enero de 2020 se evaluaron 253 pacientes de forma consecutiva para determinar su inclusion en el estudio. Se utilizaron las puntuaciones de propension estimadas en funcion de los datos demograficos, incluidos la edad, el peso corporal y la ubicacion de la inyeccion (lado derecho o izquierdo) en el brazo (n = 58) y la pierna (n = 58) de los pacientes neonatos y lactantes. A continuacion, se compararon los valores medios de TC de la arteria pulmonar, la aorta ascendente y la vena cava superior izquierda; las relaciones contraste-ruido (RCR); y las puntuaciones de visualizacion del brazo y la pierna como lugares de inyeccion. Resultados Los valores medios de TC durante la ACT para el brazo y la pierna fueron de 479,4 y 461,3 UH en la aorta ascendente, de 464,2 y 448,1 UH en la arteria pulmonar y de 232,8 y 220,1 UH en la vena cava superior izquierda, respectivamente. Los valores medios de ruido de la imagen (DE) y de RCR fueron, respectivamente, de 38,9 y 12,1 UH para el brazo y de 39,1 y 12,3 UH para la pierna. Las puntuaciones medias de visualizacion de la representacion del volumen de las imagenes 3 D fueron de 3,0 y 3,0 para los lugares de inyeccion del brazo y la pierna, respectivamente. No se observaron diferencias significativas en los valores medios de TC de la aorta ascendente, la arteria pulmonar y la vena cava superior izquierda; el valor de DE; la RCR; y las puntuaciones de visualizacion del brazo y la pierna. Conclusiones Los valores de TC del lumen de los vasos sanguineos y las puntuaciones de visualizacion de las imagenes 3 D observados durante la realizacion de una ACT en pacientes neonatos y lactantes con cardiopatias congenitas son los mismos, independientemente de si el lugar de inyeccion es el brazo o la pierna.

Obtaining CCTA images with optimal injection location such as the arm or leg is important to avoid the artifacts caused by the CM. This study compares the computed tomography (CT) numbers and visualization scores of the three-dimensional (3D) images of the lumens of the blood vessels in the arm or leg during cardiac computed tomography angiography (CCTA) in neonatal and infant patients.Between January 2017 and January 2020, 253 consecutive patients were considered for inclusion. We used the estimated propensity scores as a function of the demographic data, including age, body weight, and injection location (right or left side) in the arm (n = 58) and leg (n = 58) of neonatal and infant patients. We compared the mean CT numbers of the pulmonary artery, ascending aorta, and left superior vena cava; contrast-noise ratios (CNR); and visualization scores between the arm and leg as the injection locations.The mean CT numbers during CCTA for the arm and leg were 479.4 and 461.3 HU in the ascending aorta, 464.2 and 448.1 HU in the pulmonary artery, and 232.8 and 220.1 HU in the left superior vena cava, respectively. The mean image noise (SD) and CNR values, respectively, were 38.9 HU and 12.1 for the arm as the injection location and 39.1 HU and 12.3 for the leg as the injection location. The median visualization scores of volume rendering of the 3D images were 3.0 and 3.0 for the arm and leg injection sites, respectively. There were no significant differences in the mean CT numbers of the ascending aorta, pulmonary artery, and left superior vena cava; SD value; CNR; and visualization scores between the arm and leg injection locations.The CT numbers of the lumen of the blood vessel and visualization scores of the 3D images of the arm and leg injection locations are equal during CCTA in neonatal and infant patients with congenital heart disease.

To investigate how changing the injection duration at cardiac computed tomography angiography (CCTA) affects contrast enhancement in newborns and infants.Included were 142 newborns and infants with confirmed congenital heart disease who underwent CCTA between January 2015 and December 2018. In group 1 (n = 71 patients), the injection duration was 8 s; in group 2 (n = 71) it was 16 s. Our findings were assessed by one-to-one matching analysis to estimate the propensity score of each patient. We compare the CT number for the pulmonary artery (PA), ascending aorta (AAO), left superior vena cava (SVC), AAO and PA enhancement ratio, and the scores for visualization between the two groups.In group 1, median CT number and ranges was 345 (211-591) HU in the AAO, 324 (213-567) HU in the PA, and 62 (1-70) HU in the SVC. These values were 465 (308-669) HU, 467 (295-638) HU, and 234 (67-443) HU, respectively, in group 2 (p 0.05). The median score for volume-rendering visualization on 3D images of the CCTA was 2 in group 1 and 3 in group 2; the score for visualization of the left SVC of the maximum intensity projection images was 2 in group 1 and 3 in group 2 (p 0.05). The CT number for the AAO and PA enhancement ratio was 15.2 in group 1 and 9.2 in group 2 (p 0.05).The 16-sec injection protocol yielded significantly higher CT numbers for the AAO, PA, and the SVC than the 8-sec injection protocol; the visualization scores were also significantly higher in group 2.In newborns and infants, the longer injection time for CCTA yields stable and higher contrast enhancement at identical CM concentrations.

To compare the computed tomography (CT) number for paediatric cardiac computed tomography angiography (CCTA) and visualisation score of the three-dimensional (3D) images using the conventional T-shaped extended tube (T-tube) and spiral flow-generating extended tube (spiral-tube) connected between the contrast injector and cannula.In total, 108 patients suspected to have congenital heart disease (CHD) were considered for inclusion. We utilised the T-tube for intravenous contrast and spiral-tube in 54 patients each. Observers individually inspected randomized volume rendering images of the internal thoracic artery, each acquired from the with or without spiral-tube groups, using a four-point scale. We compared the mean CT number of the ascending aorta (AAO) and pulmonary artery (PA), contrast noise ratio (CNR), CT number for the AAO and PA enhancement ratio, and the visualisation scores between the groups.There were no significant differences in patient characteristics between the with or without spiral-tube groups (p 0.05). The mean CT number ±standard deviation for the AAO and PA, and the CNR without or with spiral-tube groups were 441.2 ± 89.2 and 489.8 ± 86.1 HU for the AAO, 436.3 ± 100.6 and 475.3 ± 85.2 HU for the PA, and 9.5 ± 2.2 and 10.8 ± 2.4 for the CNR, respectively (p 0.05). In the spiral-tube group, the CT number, CNR, and visualisations score of the 3D images were significantly higher for the AAO and PA than those in the T-tube group (p 0.05).The spiral-tube proved to be beneficial in improving the CT number for the AAO and PA, CNR, and visualisation score compared with the conventional T-tube during paediatric CCTA.The spiral-tube may allow the visualisation of smaller blood vessels than those visualised by the conventional T-tube for paediatric patients in CCTA.

Introduction Deep learning approaches have shown high diagnostic performance in image classifications, such as differentiation of malignant tumors and calcified coronary plaque. However, it is unknown whether deep learning is useful for characterizing coronary plaques without the presence of calcification using coronary computed tomography angiography (CCTA). The purpose of this study was to compare the diagnostic performance of deep learning with a convolutional neural network (CNN) with that of radiologists in the estimation of coronary plaques. Methods We retrospectively enrolled 178 patients (191 coronary plaques) who had undergone CCTA and integrated backscatter intravascular ultrasonography (IB-IVUS) studies. IB-IVUS diagnosed 81 fibrous and 110 fatty or fibro-fatty plaques. We manually captured vascular short-axis images of the coronary plaques as Portable Network Graphics (PNG) images (150 × 150 pixels). The display window level and width were 100 and 700 Hounsfield units (HU), respectively. The deep-learning system (CNN; GoogleNet Inception v3) was trained on 153 plaques; its performance was tested on 38 plaques. The area under the curve (AUC) obtained by receiver operating characteristic analysis of the deep learning system and by two board-certified radiologists was compared. Results With the CNN, the AUC and the 95% confidence interval were 0.83 and 0.69–0.96, respectively; for radiologist 1 they were 0.61 and 0.42–0.80; for radiologist 2 they were 0.68 and 0.51–0.86, respectively. The AUC for CNN was significantly higher than for radiologists 1 (p = 0.04); for radiologist 2 it was not significantly different (p = 0.22). Conclusion DL-CNN performed comparably to radiologists for discrimination between fatty and fibro-fatty plaque on CCTA images. Implications for practice The diagnostic performance of the CNN and of two radiologists in the assessment of 191 ROIs on CT images of coronary plaques whose type corresponded with their IB-IVUS characterization was comparable.

The electrical insulation of the Megavolt ITER Injector and Concept Advancement (MITICA) beam source (BS) at 1 MV in vacuum is a challenging issue, which could not be fully addressed so far on the basis of experimental results and of theoretical models available in literature. A specific high-voltage (HV) test campaign is being prepared to validate and optimize the voltage holding capability of the BS insulation under realistic conditions, using full-size mockup electrodes reproducing in detail the geometry of the BS and accelerator. The proposed test strategy will address both the single-gap and the multistage insulation, so as to obtain a verification of voltage holding at 1 MV before the installation of the real components. This approach is intended to reduce the risk related to the HV insulation at 1 MV and, if necessary, to allow the development of effective corrections. In this article, the test motivations and requirements are defined, and the electrode implementation and diagnostic setup are described. Finally, the test configurations and the experimental procedure are discussed.

This study aims to predict endoleak after endovascular aneurysm repair (EVAR) using machine learning (ML) integration of patient characteristics, stent-graft configuration, and a selection of vessel lengths, diameters and angles measured using pre-operative computed tomography angiography (CTA).We evaluated 1-year follow-up CT scans (arterial and delayed phases) in patients who underwent EVAR for the presence or absence of an endoleak. We also obtained data on the patient characteristics, stent-graft selection, and preoperative CT vessel morphology (diameter, length, and angle). The extreme gradient boosting (XGBoost) for the ML system was trained on 30 patients with endoleaks and 81 patients without. We evaluated 5217 items in 111 patients with abdominal aortic aneurysms, including the patient characteristics, stent-graft configuration and vascular morphology acquired using pre-EVAR abdominal CTA. We calculated the area under the curve (AUC) of our receiver operating characteristic analysis using the ML method.The AUC, accuracy, 95% confidence interval (CI), sensitivity, and specificity were 0.88, 0.88, 0.79-0.97, 0.85, and 0.91 for ML applying XGBoost, respectively.The diagnostic performance of the ML method was useful when factors such as the patient characteristics, stent-graft configuration and vessel length, diameter and angle of the vessels were considered from pre-EVAR CTA.Based on our findings, we suggest that this is a potential application of ML for the interpretation of abdominal CTA scans in patients with abdominal aortic aneurysms scheduled for EVAR.

The purpose of this study was to demonstrate that dose reduction does not compromise image quality when combining high helical pitch (HP) and the ECG-Edit function during low HP retrospectively gated computed tomography angiography (CTA).This study made use of a pulsating cardiac phantom (ALPHA 1 VTPC). The heart rate (HR) of the cardiac phantom was changed in five intervals, every 5 beats per minute (bpm), from 40 to 60 bpm. Evaluation of a range of HR was important because data loss might occur when combining a low HR and high HP. We performed retrospectively gated CTA scans five times using a low HP (0.16) and high HP (0.24), for each of the five HR intervals, using a 64-detector row CT scanner. The CT volume dose index (CTDIData loss occurred with a HR of 40 bpm and 45 bpm when using HP 0.24. The CTDIThe ECG-Edit function is potential useful for repairing the lost data in patients with a low HR, and when combined with a high HP, it is possible to reduce the radiation dose by approximately 33%.The ECG-Edit function and high HP may be a viable option in pediatric CTA studies.

A scaling technique has been developed in order to predict the voltage holding capability of the world-largest electrostatic accelerator for fusion application having a long gap vacuum insulation around 1 m with large surface area of more than 6 m2. One of critical issues for design of such large-size accelerator is the development of the prediction model based on the experimental results. For this purpose, the 1/5 scale mockup has been developed, which is composed of the 5-stage accelerator with the high voltage bushing in the vacuum vessel. Direct comparison of the sustainable voltages in the 1/5 scale and full-scale high voltage busing only shows that a voltage scaling in 1/5 scale size is 55%. It was found that the voltage scaling is consistent with the prediction based on the empirical scaling according to the surface area and gap length. As a result, the voltage holding capability of the 1/5 scale mockup is 400 kV in the experiment, which indicates an estimation of 720 kV in full-scale with a real configuration. This is the first experiment-based prediction of the voltage holding capability for the largest accelerator for ITER. The improvement of the voltage holding capability has been already planned by using multi-layer electrostatic shields. In such experiment, the developed scaling technique is useful to predict the voltage holding capability for large vacuum components which can not be easily tested.

This study aimed to compare the correlation between the computed tomography (CT) enhancement rate of the venous to portal venous phase (VP-ER) and the extracellular volume (ECV) fraction with shear-wave ultrasound elastography (USE) findings in patients with liver fibrosis.We included 450 patients with clinically suspected liver cirrhosis who underwent triphasic dynamic CT studies and USE. We compared the USE results with the unenhanced CT phase, with enhancement in the hepatic artery phase (HAP), portal venous phase (PVP), and venous phase (VP), and with the ECV fraction and the VP-ER. We also compared the area under the curve (AUC) of the receiver operating characteristic (ROC) curve of the ECV fraction and VP-ER with that of the values obtained with USE.The VP-ER was the most highly correlated with the liver stiffness value determined with USE (Pearson's correlation coefficient: r = 0.37), followed by enhancement in the PVP (r = -0.25), CT number on unenhanced CT scans (r = -0.22), the ECV fraction (r = 0.19), enhancement in the VP (r = 0.059), and enhancement in the HAP (r = -0.023) (all p 0.01). The VP-ER showed a significantly higher AUC than the ECV fraction (0.75 vs 0.62) when the liver stiffness was15 kPa in USE studies (p = 0.04).Compared to the ECV fraction, the VP-ER is more useful for predicting all degrees of liver fibrosis on routine triphasic dynamic CT images.Although improvement is needed, the VP-ER has a higher diagnostic ability for liver fibrosis than the ECV fraction in clinical practice.

A beam optics study using the ITER-relevant high intense negative ion beams, such as 1 MeV, 200 A/m2, has been performed experimentally and analytically using a multi-aperture and five-stage accelerator. Initially, multi-beamlets generated from this accelerator were deflected in various directions due to the magnetic field and space charge repulsion between beams and showed various divergences. These had limited the pulse length and the beam energy. Compensation methods of the beamlet deflections have worked effectively and contributed to achieving the ITER requirement, the divergence angle of

Beam optics of the ITER prototype accelerator with 88 mm acceleration gap length has been examined through H- beam acceleration tests at the ITER target beam perveance. The beam optics has been examined for beam energies up to 790 keV under the ITER target perveance. The total grid heat load was successfully reduced to 10 %, which was lower than the allowable value of 15 %. The beam emittance of the ITER perveance has been measured for the first time by using newly developed emittance measurement system consisting of carbon-fiber-composite (CFC) plate with pin-holes. The emittance of 790 keV H- beam shows the divergence angle of the beam core is satisfied with the ITER requirement of

A protection system of ion source components from local abnormal discharge has been developed with ITER-class filament-driven negative ion source for high power and stable long-term operation. Protection from unpredictable discharge is a common issue for filament and RF-driven ion sources. To understand how fast should be cut off the discharge, threshold energy not to cause critical damage on the filament was investigated. The experimental exploration concluded that the energy less than 1.87 J or fast cut-off faster than 343 μs is the threshold for the robust protection of the filaments. A developed system successfully detected and cut off the discharge at 100 μs under noisy environments with the high current power supply. Moreover, the detection system is remotely adjustable. Such versatile protection system can contribute to any abnormal discharges in high current system including various ion sources, gyrotron, and high voltage components.

As a challenge to measure the extraction surface of the negative ion beam, a laser Thomson scattering system with high spatial resolution was applied to a weakly ionized plasma in a negative ion source for the first time. The first target was to measure electron density around extraction region because shape of the extraction surface can be estimated by electron spatial profile. However, stray light by injected laser, filament and plasma was too intense compared to signal from the low density region. To solve this, a triple grating spectroscopy and a multilayer black screen were introduced, and the laser spot size was minimized to reduce slit sizes of the spectroscopy. As a result, electron density was successfully measured accurately in low density region. From an error estimation, measurement of electron density 3 × 1016 m-3 with spatial resolution of 0.5 mm at extraction region can be realized with accumulation of signals from multiple laser shots. This system can contribute to the understanding of the mechanism of formation of the extraction surface, which is a long-term issue in the negative ion source.

Reverse calculation of negative ion trajectory based on the measured beam emittance has been performed for the first time in multi-stage accelerator in order to reconstruct negative ion profile near meniscus, which has been a long-term issue for negative ion sources. According to reverse calculation, negative ions are mainly extracted from the periphery of extraction area, and the particles extracted from the aperture edge is lost on acceleration grids. By taking into account the lost component with reconstructed negative ion profile, the negative ion trajectory became consistent with observed beam traces on the acceleration grids. This result can be applied directly to the design of ITER accelerator as well as the other Cs-seeded negative ion sources.

The negative ion beam optics is studied quantitatively from the viewpoints of the heat loads due to the beam halo in the accelerator and the emittance of the negative ion beam by using the 3D3V PIC model combined with a Monte Carlo calculation, in which negative ion beam from plasma meniscus formation to the beam acceleration is modeled. As for the heat loads of the A2G and the GRG, the simulation result almost agrees with the experimental result. The simulation result indicates that the secondary electrons from the extractor also contribute to the heat load of the A1G. Moreover, the normalized rms emittance of the negative ion beam after the exit of the GRG are estimated to be around 0.25π mm mrad, which are compatible with the typical values of the negative ion sources.

The energy relaxation processes of the surface produced H- ions due to the Coulomb collision and the charge exchange collision is verified by using 3D3V-PIC (three dimensions in real space and three dimensions in velocity space particle in cell) simulation. Under the present simulation condition (ne = 1.0 × 1018 m−3, TH+ = 0.25 eV, TH- = 1.5 eV (the initial temperature of the surface produced H- ion), nH/nH2 =0.5, nH = 9.4 × 1018 m-3, TH = 0.1 eV), it is indicated the Coulomb collision is dominant for the energy relaxation processes. Moreover, it is indicated from the emittance diagrams that the H− ion beam optics is improved by the energy relaxation processes.

A high power density and a long pulse negative ion beam accelerator has been developed in QST to realize the ITER neutral beam accelerator. A main target was the H− ion beam acceleration up to 1 MeV with 200 A/m2 for 60 s. After the achievement of 1 MeV at a short pulse, the pulse length has been gradually extended by modifications of grid configurations to suppress grid heat loads due to negative ions and electrons. However, the beam energy was limited up to 0.7 MeV at 60 s operation. One issue was an unstable negative ion production for a long time due to arcing and excess temperature rise of a plasma grid for optimum negative ion production. To suppress arcing, a cathode filament shape was modified. The plasma grid was modified to have a large heat capacitance in order to suppress temperature rise for 60 s operation at high discharge power required for 1 MeV operation. Another issue is to optimize beam optics more precisely. Fine tuning of the 1st acceleration stage was carried to improve beam optics f...

In order to evaluate deposition of cesium (Cs) in the plasma grid (PG) and investigate the origin of the gradual degradation of the negative ion current in a 100 s long pulsed operation in the JT-60SA negative ion source, Cs behavior in the source is model. To do this, Cs adsorption/desorption coefficient with a wide range of temperature is experimentally measured by a surface ionization detector and a quartz crystal microbalance. As a result, both of the adsorption and desorption are drastically varied at temperature range from room temperature to 100 °C. Based on these data, the model calculates the amounts of the Cs mass in the chamber wall and PG. The calculation result shows that, in the operation, an increase of temperature in the chamber wall (Twall) causes the evaporation of the huge amount of Cs in it. This leads to over pilling-up of Cs in the PG and the slight degradation of the negative ion production. Therefore, it is found that the constant temperature operation is needed to sustain the thickness of the Cs monolayer in the PG, and the Twall is desired to be less than 60 °C to suppress the evaporation of Cs in the chamber wall. According to this model, it is showed that there are many combinations of the temperatures to achieve it with low Cs consumption.In order to evaluate deposition of cesium (Cs) in the plasma grid (PG) and investigate the origin of the gradual degradation of the negative ion current in a 100 s long pulsed operation in the JT-60SA negative ion source, Cs behavior in the source is model. To do this, Cs adsorption/desorption coefficient with a wide range of temperature is experimentally measured by a surface ionization detector and a quartz crystal microbalance. As a result, both of the adsorption and desorption are drastically varied at temperature range from room temperature to 100 °C. Based on these data, the model calculates the amounts of the Cs mass in the chamber wall and PG. The calculation result shows that, in the operation, an increase of temperature in the chamber wall (Twall) causes the evaporation of the huge amount of Cs in it. This leads to over pilling-up of Cs in the PG and the slight degradation of the negative ion production. Therefore, it is found that the constant temperature operation is needed to sustain the thic...

To understand the physics of the cesium (Cs) recycling in the large Cs-seeded negative ion sources relevant to ITER and JT-60SA with ion extraction area of 45-60 cm × 110-120 cm, the time evolution of the negative ion profile was precisely measured in JT-60SA where the ion extraction area is longitudinally segmented into 5. The Cs was seeded from the oven at 180 °C to the ion source. After 1 g of Cs input, surface production of the negative ions appeared only in the central segment where a Cs nozzle was located. Up to 2 g of Cs, the negative ion profile was longitudinally expanded over full ion extraction area. The measured time evolution of the negative ion profile has the similar tendency of distribution of the Cs atoms that is calculated. From the results, it is suggested that Cs atom distribution is correlated with the formation of the negative ion profile.

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

Design techniques for the vacuum insulation have been developed in order to realize a reliable voltage holding capability of multi-aperture multi-grid (MAMuG) accelerators for fusion application. In this method, the nested multi-stage configuration of the MAMuG accelerator can be uniquely designed to satisfy the target voltage within given boundary conditions. The evaluation of the voltage holding capabilities of each acceleration stages was based on the previous experimental results about the area effect and the multi-aperture effect. Since the multi-grid effect was found to be the extension of the area effect by the total facing area this time, the total voltage holding capability of the multi-stage can be estimated from that per single stage by assuming the stage with the highest electric field, the total facing area, and the total apertures. By applying these consideration, the analysis on the 3-stage MAMuG accelerator for JT-60SA agreed well with the past gap-scan experiments with an accuracy of less than 10% variation, which demonstrated the high reliability to design MAMuG accelerators and also multi-stage high voltage bushings.

In order to realize negative ion sources and accelerators to be applicable to International Thermonuclear Experimental Reactor and JT-60 Super Advanced, a large cesium (Cs)-seeded negative ion source and a multi-aperture and multi-stage electric acceleration have been developed at Japan Atomic Energy Agency (JAEA). Long pulse production and acceleration of the negative ion beams have been independently carried out. The long pulse production of the high current beams has achieved 100 s at the beam current of 15 A by modifying the JT-60 negative ion source. The pulse duration time is increased three times longer than that before the modification. As for the acceleration, a pulse duration time has been also extended two orders of magnitudes from 0.4 s to 60 s. The developments of the negative ion source and acceleration at JAEA are well in progress towards the realization of the negative ion sources and accelerators for fusion applications.

The physical mechanism of the formation of the negative ion beam halo and the heat loads of the multi-stage acceleration grids are investigated with the 3D PIC (particle in cell) simulation. The following physical mechanism of the beam halo formation is verified: The beam core and the halo consist of the negative ions extracted from the center and the periphery of the meniscus, respectively. This difference of negative ion extraction location results in a geometrical aberration. Furthermore, it is shown that the heat loads on the first acceleration grid and the second acceleration grid are quantitatively improved compared with those for the 2D PIC simulation result.

Asbestos, a naturally occurring fibrous mineral, causes malignant mesothelioma (MM). However, it takes a very long time to develop MM, which suggests that effects other than tumorigenicity of asbestos might contribute to the development of MM, and one of the possible targets is anti-tumor immunity. Therefore, we examined the effect of asbestos exposure on human natural killer (NK) cells using the cell line of YT-A1, Peripheral blood mononuclear cells (PBMCs) cultures and specimens from patients with MM. In particular, we focused on expression of NK cell-activating receptors, including NKG2D, 2B4 and NKp46. Analysis of the YT-CB5 subline of YT-A1, cultured with CB for over 5 months, showed a decrease in cytotoxicity with low expressions of NKG2D and 2B4, although there were no decreases after about one month. YT-CB5 showed decreases in phosphorylation of extracellular signal-regulated kinase (ERK) and degranulation stimulated by antibodies to NKG2D. Peripheral blood (PB-) NK cells from MM patients also showed decreased cytotoxicity compared with healthy volunteers (HV), and was accompanied with low expression of NKp46 unlike YT-CB5. PBMCs cultured with CB resulted in decreased expression of NKp46 on NK cells, although this did not occur when using glass wool, an asbestos substitute. These results indicate that asbestos has the potential to suppress cytotoxicity of NK cells. In particular, it is noteworthy that both NK cells from MM patients and those from a culture of PBMCs derived from HVs with asbestos showed the same characteristic of decreased cytotoxicity with low expression of NKp46.

Noninductive plasma current (Ip) start‐up experiments using RF power in the lower hybrid frequency range are being conducted on the TST‐2 spherical tokamak. The lower hybrid wave (LHW) has demonstrated efficient current drive in conventional tokamaks. However, in spherical tokamak (ST) plasmas with very high dielectric constants (;e∼ωpe2/Ωe2≫1), accessibility of the LHW to the plasma core is severely limited. Our approach is to keep the plasma density low (such that e∼1) during Ip ramp‐up. Once Ip reaches a level sufficiently high for neutral beam current drive, plasma can be densified and transformed into an advanced tokamak plasma dominated by the self‐driven bootstrap current. Initial plasma start‐up experiments were performed on TST‐2 using a combline antenna which excites a traveling fast wave. After formation of toroidal flux surfaces, RF power and vertical field were ramped up to increase Ip. Up to 12 kA of Ip has been obtained by this method. Soft X‐ray measurements indicate that the electron temp...

Plasma current start‐up experiments using the lower hybrid wave (LHW) excited by a new dielectric loaded waveguide array antenna are planned on TST‐2. The wave excitation efficiency of this antenna is investigated using a versatile FEM solver package, COMSOL. Propagation and absorption of the LHW are calculated by iterating between the TORLH full wave code and the CQL3D Fokker‐Planck code. Wave absorption is very weak for Maxwellian plasma, but becomes stronger as the quasilinear deformation of the distribution function develops.

Treatment of a case of widespread superficial oral squamous cell carcinoma with external beam irradiation, followed by high dose rate Microselectron mould radiotherapy, is reported. The tumor disappeared macroscopically after treatment, but there was infield recurrence in the buccogingival sulcus where the radiation dose might have been inadequate. Apart from some radiation mucositis within the treated area, edema and a superficial ulcer were observed in the tongue. These were considered to be due to radiation overdose. Although there is room for improvement, this mode of treatment has something to offer patients with hard-to-cure cancer.

Detection and diagnosis of human malignant melanoma by Positron Emission Tomography (PET) using 18F-10B-L-BPA, a specific melanogenesis-seeking compound synthesized for use in Boron Neutron Capture Therapy for malignant melanoma (NCT), has been developed. This resulted in a novel, highly effective methodology for the selective three dimensional imaging of metastatic malignant melanomas, and for accurate determination of 10B concentration in the tumor and surrounding tissue, providing almost all diagnostic information necessary for complete non-invasive radiation dose planning in the treatment of malignant melanoma both for NCT as well as other therapeutic modalities.

A patient with malignant melanoma on the left foot was treated by thermal neutron capture therapy using 10B-paraboronophenylalanine. We compared the actual (clinical) response with the predicted response estimated using our past experimental and clinical data, and discussed some problems to be overcome in the future.We adopted an intravenous drip infusion of the compound whereby 170 mg/kg of the drug was administered over 4-5 hours before neutron irradiation. The patient was then irradiated with thermal neutrons from the Musashi Reactor at a reactor power of 100 kW and a neutron flux of 1.0 x 10(9) n/cm2/s at the collimator surface. The total absorbed dose to the melanoma and the surrounding skin was calculated by multiplying the thermal neutron fluences by the conversion factor.The total absorbed doses to the melanoma and the surrounding normal skin were calculated as 19.0 and 9.4 Gy, respectively. These absorbed doses were estimated at 33.5 and 14.2 RBE-Gy, respectively, assuming that the relative biological effectiveness (RBE) of the high LET radiations was 2.0 and that each component of the mixed radiation was simply additive. The melanoma showed marked regression with mild skin reaction (dry desquamation) a month after therapy, and finally disappeared 10 months after therapy. There were no no substantial side effects.We concluded that the outcome of our calculated dose values agreed well with the clinical response and that their compatibility indicated considerable validity for our approach. However, there are still some problems-uncertainty concerning the 10B concentration in tumor and skin, determination of the total absorbed dose, and a single curative dose for malignant melanoma-to be overcome with regard to clinical use of this therapy.

A treatment regimen for boron neutron capture therapy of malignant melanomas is described using 10B-paraboronophenylalanine as the tumor-targeting compound. As a therapeutic dose, we adopted the maximum tolerable dose for the skin regardless of tumor 10B concentration. In practice, the maximum neutron fluence should be decided prior to starting irradiation. For this purpose, the kinetics of the concentration of 10B in the blood and skin and the skin-to-blood ratios were analyzed in the six patients who received 170 mg/kg of the compound intravenously, and skin concentrations during irradiation were predicted using a standard skin factor curve. This yields a skin concentration at time T based on the blood concentration at time 0. We calculated the maximum tolerable fluence yielding but not exceeding 18 RBE-Gy by assuming that the RBE of 14N(n,p)14C and 10B(n, alpha)7Li reaction for skin damage is 2.5. Actual skin reactions in three of five patients treated with the therapy were, as predicted, within tolerable limits, and we were able to obtain complete tumor regression in four cases. The results indicate that application of our logical approach will be useful for subsequent cases and further development of this therapy.

Significant increases in the serum levels of cancer antigen 125 (CA125) and carbohydrate antigen 19-9 (CA19-9) were observed over one month prior to the removal of an ovarian adenofibroma. The serum levels of CA125 and CA19-9 decreased rapidly after surgery. The surface of the tumor at surgery showed marked inflammation, probably induced by the necrosis produced by torsion. Pathologically, most of the tumor was necrotic, and histoimmunochemical staining of the viable cells was weak for CA125 but intense for CA19-9. Clinicopathological observations of the case suggested that CA125 and CA19-9 might be stimulated in the cells by inflammation or that originally existing CA125 and CA19-9 were released from the tumor cells following the cell necrosis.

From October 1986 through December 1991, 30 patients with locally recurrent lung cancer were treated by local hyperthermia combined with radiotherapy at the Kawasaki Medical School Hospital. Local heat was applied with 13.56 MHz radiofrequency (RF) capacitive heating equipment twice a week after radiotherapy for 40-60 minutes per session. The tumor temperatures of only a few patients (three patients) could be measured directly by thermocouples inserted into the tumors because of anatomical difficulties. Based on thermometrical results, it was estimated that the maximum tumor temperature was about 41 degrees C. When we consider the extensive low density areas often appearing in CT scan images following this combined therapy (NR2), the tumor response was as follows: CR 0, PR 5 (18%), NR 13 (40%), NR2 10 (36%), and PD 0. The local response rate (CR+PR+NR2) was 54%. The median survival time after the onset of retreatment was 12.8 months in PR cases, 7.1 months in NR cases and 24.1 months in NR2 cases. There was a statistically significant difference (p0.01) in the median survival times for NR and NR2 cases. From the standpoint of prognosis, we concluded that NR2 was a condition comparatively similar to clinical PR.

The relative biological effectiveness (RBE) of 10B-neutron capture therapy (BNCT) on skin was analyzed using hamsters. The Kyoto University Research Reactor, which has a very low contamination of gamma rays and fast neutrons, was used as a thermal neutron source. Boron-10-para-boronophenylalanine hydrochloride ([10B]BPA.HCl) was administered to the hamsters. The evolution and time course of early skin reactions were assessed. These reactions were compared with those produced by electron beams. The maximum safe skin doses (no more than moist desquamation) of BNCT and electron beams were established to be 11 and 21 Gy, respectively. The RBE at this single dose with BNCT was found to be 1.94, assuming that the RBE of the gamma rays was 1.0 and each component of BNCT (mixed radiations) was simply additive.

Eight patients with bile duct carcinoma were treated with radiotherapy using intracatheter 198Au grains. The intracatheter 198Au grains in an inner tube were inserted into a percutaneous transhepatic catheter. A plastic tip was placed between these grains to improve spatial and temporal dose allocation. This method and 192Ir wire irradiation resemble each other closely in dose distribution, but the former has the following advantages over the latter. 1) The number of 198Au grains used can be changed quite easily in accordance with the length of the stenosis. 2) The half-life of 198Au is about 2.7 days, and a dose of 25-40 Gy at 1.0 cm from the source is delivered over this period. The medical staff can protect themselves from radioactivity when the sources are withdrawn after brachytherapy. 3) 192Ir wire is not used very frequently in spite of its long half-life (74 days) because bile duct carcinoma is uncommon. 4) In Japan, 198Au grains can be purchased on a weekly basis, so treatment plans can be easily made. The eight patients also received external irradiation and the median survival after onset of radiotherapy was 7.9 months. There have been few systemic or local complications.

From October 1986 through December 1989, 18 patients with locally recurrent lung cancer were treated by local hyperthermia combined with radiotherapy at the Kawasaki Medical School Hospital. Nine patients were initially treated by radiotherapy for inoperable lung cancer or as adjunct postoperative therapy. The other 9 were initially treated by chemotherapy or operation. Local heat was applied with a 13.56 MHz radiofrequency (RF) capacitive heating equipment, twice a week after radiotherapy, for 45-60 minutes per session. The results were compared with 17 patients with locally recurrent tumors which were treated by radiation therapy alone between January 1981 and September 1986. Tumor temperatures of two patients were measured directly by thermocouples inserted into the tumors which partially attached to the chest wall. As we were unable to measure tumor temperatures in the other 16 because of the anatomical difficulty, we measured the temperatures of the esophagus as near as possible to these lesions. Based on thermometry results, it was estimated that the maximum tumor temperatures were about 40-41 degrees C. The local response rates (CR + PR) were 25% in patients treated with combined therapy and 7% in those with RT alone. The median survivals after onset of retreatment were 10.7 months and 5.0 months, a statistically significant difference being demonstrated. Severe complications were not seen in this treatment.

From 1976 to 1988, 33 patients with a prostatic cancer were treated with radiotherapy at Kawasaki Medical School. The age of these patients ranged from 45 to 82 with the average being 69 years. The actuarial 5 year survival rates for patients in stages B (n = 6), C (n = 12), D1 (n = 5), or D2 (n = 10) were 100%, 65%, 50%, and 40%, respectively. The for those with an adenocarcinoma that was well differentiated (n = 5), moderately differentiated (n = 13), or poorly differentiated (n = 15) was (were?) 100%, 58%, and 41%, respectively.