Efficacy of Plasma free Hemoglobin for detecting centrifugal pump thrombosis.

INTRODUCTION: Lactate dehydrogenase (LDH) is widely used as an indicator of pump thrombosis in a centrifugal pump. However, due to the low specificity of LDH, pump thrombosis is difficult to detect in the clinical environment. We measured plasma free hemoglobin (pfHb) with the portable device in ICU. The goal of this investigation is to evaluate its diagnostic ability for pump thrombosis. METHODS: We enrolled 31 consecutive patients who needed Extracorporeal Membrane Oxygenation (ECMO) therapy and pfHb was determined with HemoCue® plasma/Low Hb photometer. Pump thrombosis was analyzed macroscopically at the timing of pump explantation or exchange. Also, we divided the pump thrombosis into a grading scale by the place of thrombosis. RESULTS: The median of peak pfHb was significantly lower in the none thrombus group (0.03 g/dL) than that of in the thrombus group (0.05g/dL) (p = 0.01). In our grading criteria, pfHb was significantly higher when the thrombus is existing near the shaft (p = 0.015). Contrary, no significant difference was found for LDH.The ROC analysis of pfHb revealed an AUC of 0.77 for detecting pump thrombosis with the best statistical cutoff value at 0.05 g/dL (specificity, 78%; sensitivity, 77%). Also, ROC analysis of LDH was performed (AUC, 0.44; cutoff value, 1200 IU/L; specificity, 59%; sensitivity, 54%) and compared with pfHb. AUC was significantly higher in pfHb (p = 0.04). CONCLUSION: Our results showed the efficacy of pfHb for detecting centrifugal pump thrombosis.

NEW IDEA FOR DETERMINING THE OPTIMAL NUMBER OF MEASUREMENTS IN ABSORBED DOSE-TO-WATER MEASUREMENT OF HIGH-ENERGY PHOTON BEAM.

This study presents a new idea for estimating the number of measurements required for determining the uncertainty in obtaining the desired water absorbed dose using the variation obtained from multicenter absorbed dose measurement data. The number of dose measurements depends on the performance of each linear accelerator (LINAC) tested and the dosimetry equipment and procedure used. However, optimising the number of data collected for the absorbed dose to water has been inadequately reported. Using the absorbed dose measurement data collected 10 times as a reference value, we will compare the changes in the variation of the measurement results caused by the difference in the number of repeated measurements of the absorbed dose. The number of measurements is determined statistically such that this variation would be smaller than the change in absorbed dose. Thus, we can determine the optimum number of measurements suitable for the variability of each LINAC.

[Material Investigation for the Development of Non-rigid Phantoms for CT-MRI Image Registration].

PURPOSE: In radiotherapy, deformable image registration (DIR) has been frequently used in different imaging examinations in recent years. However, no phantom has been established for quality assurance for DIR. In order to develop a non-rigid phantom for accuracy control between CT and MRI images, we investigated the suitability of 3D printing materials and gel materials in this study. METHODS: We measured CT values, T1 values, T2 values, and the proton densities of 31 3D printer materials-purchased from three manufacturers-and one gel material. The dice coefficient after DIR was calculated for the CT-MRI images using a prototype phantom made of a gel material compatible with CT-MRI. RESULTS: The CT number of the 3D printing materials ranged from -6.8 to 146.4 HU. On MRI, T1 values were not measurable in most cases, whereas T2 values were not measurable in all cases; proton density (PD) ranged from 2.51% to 4.9%. The gel material had a CT number of 111.16 HU, T1 value of 813.65 ms, and T2 value of 27.19 ms. The prototype phantom was flexible, and the usefulness of DIR with CT and MRI images was demonstrated using this phantom. CONCLUSION: The CT number and T1 and T2 values of the gel material are close to those of the human body and may therefore be developed as a DIR verification phantom between CT and MRI. These findings may contribute to the development of non-rigid phantoms for DIR in the future.

Variety of c-axis collective excitations in layered multigap superconductors.

We present a dynamical theory for the phase differences along a stacked direction of intrinsic Josephson junctions (IJJ's) in layered multigap superconductors, motivated by the discovery of highly anisotropic iron-based superconductors with thick perovskite-type blocking layers. The dynamical equations describing ac and dc intrinsic Josephson effects peculiar to multigap IJJ's are derived, and collective Leggett mode excitations in addition to the Josephson plasma established in single-gap IJJ's are predicted. The dispersion relations of their collective modes are explicitly displayed, and the remarkable peculiarity of the Leggett mode is demonstrated.

Mechanism of terahertz electromagnetic wave emission from intrinsic Josephson junctions.

Using a 3D parallelepiped model of the stack of intrinsic Josephson junctions, we calculate the cavity resonance modes of Josephson plasma waves excited by external electric currents. The cavity modes accompanied by static phase kinks of the order parameter have been intensively investigated. Our calculation shows that the kink phase state is unfavorable, since the static phase kinks reduce the order parameter amplitude and thus the superconducting condensation energy. We point out that the oscillating magnetic field of the cavity mode penetrates the vacuum from the sample surfaces and the energy of the magnetic field plays an important role to determine the orientation of the cavity resonance mode. On the basis of the above discussions, we calculate the I-V characteristic curve, the THz wave emission intensity and the other physical quantities.

Theory of heterotic superconductor-insulator-superconductor Josephson junctions between single- and multiple-gap superconductors.

Using the functional integral method, we construct a theory of heterotic superconductor-insulator-superconductor Josephson junctions between one- and two-gap superconductors. The theory predicts the presence of in-phase and out-of-phase collective oscillation modes of superconducting phases. The former corresponds to the Josephson plasma mode whose frequency is drastically reduced for +/- s-wave symmetry, and the latter is a counterpart of Leggett's mode in Josephson junctions. We also reveal that the critical current and the Fraunhofer pattern strongly depend on the symmetry type of the two-gap superconductor.