Triple Energy Research Articles

(Invited) Linear and Nonlinear Optical Properties of Individual Silicon Nanowires

High-refractive index semiconductor nanostructures provide original optical properties thanks to the occurrence of size- and shape-dependent optical resonances, which can be used to enhance and engineer light-matter interaction. In particular scattering and absorption efficiencies or local electromagnetic field intensity can be amplified and spectrally tuned, opening a multitude of possible applications in photovoltaics or field-enhanced spectroscopies. High-refractive index semiconductor nanostructures have thus attracted increasing interest as low-loss alternatives to plasmonic particles. In photonics, nonlinear optical effects also play an important role, providing several functionalities such as coherent up-conversion of light, generation of short pulses, or all-optical signal processing. A hindrance is that nonlinear effects are intrinsically weak. Plasmonic nanostructures, acting as nanoantennas able to strongly localize far-field radiations, are very promising candidates to improve nonlinear optical effects, which is one of the reasons of the increasing interest for nonlinear plasmonics. However, as mentioned above, plasmonic nanoparticles usually suffer from high losses. As an alternative, enhanced nonlinear properties can be obtained in semiconductor nanostructures by properly using resonant optical modes. For example, intense second harmonic generation (SHG) was achieved in nanowires of III-V compounds, or enhanced third harmonic generation (THG) could be produced in silicon nanostructures. SHG (THG) corresponds to the coherent conversion of two (three) low-energy photons into a single photon at double (triple) energy. SHG from bulk centrosymmetric materials including silicon is impossible in the dipole approximation, since they have vanishing second order susceptibility (the inversion symmetry forbidding even order terms in the electric polarization expansion). Second order processes can therefore occur only when symmetry is broken, for instance in the presence of interfaces or field gradients. For very small systems, the high surface to volume ratio allows that rather strong second order effects may arise, possibly further supported by local field enhancement due to resonant modes. This can be interesting for silicon-based photonics compatible with CMOS technology. We present here linear and nonlinear properties of individual strain-free silicon nanowires (Si-NWs). First, we show experimentally and theoretically the optical resonance modes (Mie resonances) supported by the NW as function of diameter and polarization of the excitation, and how these modes may be used to modify the photoluminescence of Si nanocrystals placed in the NW near-field. Second, we investigate the nonlinear emission composed of a broad nonlinear PL band and the SH peak. We show that SHG from the Si-NWs is strongly increased if a Mie optical mode corresponding to the fundamental (laser) wavelength is supported by the nanowire. According to nonlinear scattering theory and the so-called Miller's rule, the highest SHG is predicted for an optimum overlap of resonant modes and linear susceptibilities, at both the fundamental and harmonic wavelengths, respectively. Contrary, no SHG can be detected in absence of any resonance. This behavior as well as experimental SHG mappings of individual Si-NWs, are well reproduced by numerical simulations (Green Dyadic Method - GDM). In first approximation, second order effects in centrosymmetric nanostructures are modeled assuming that the c2 ^^^ surface contribution from field components normal to the surface are the most significant. Other possible sources of SHG are neglected in a first step as commonly done. However, this approach fails explaining the polarization behavior of the SHG from Si-NWs with diameters up to about 150 nm. Using the c2 ^^^ surface contribution leads to SHG polarization perpendicular to the Si-NW axis, independently of the polarization of the incident light parallel of perpendicular to the nanowire axis. This is in contradiction with the experimental findings where, for small diameters below 150 nm, the polarization of both fundamental and harmonic radiations are always observed parallel. Thus, the SH polarization is found parallel to the Si-NW axis for TM excitation (incident electric field along the axis). Using GDM, we explain this behavior with SHG contributions arising from tangential fields at the surface as well as from strong field gradients in the bulk, proving that there is a changeover of the main SHG contribution as function of NW diameter. In summary, Si-NWs provide useful research tools for the investigation of SHG from centrosymmetric materials, with the possibility to address different nonlinear susceptibility contributions. They could also be interesting for nonlinear silicon-based photonic applications if enhanced SHG and polarization control could be achieved. We finally show a few examples of Si nanostructures obtained by e-beam lithography in Silicon On Insulator substrates in order to explicitly tailor the SH response.

Grain microstructural evolution in 2D and 3D polycrystals under triple junction energy and mobility control

Grain growth in two- and three-dimensional nanocrystalline materials is modeled by modifying the Monte Carlo Potts method based on the assumption that grain boundaries as well as triple junctions can be rate limiting during coarsening. To that aim each type of junction-associated lattice points (grain boundary-associated and triple junction-associated) is assigned an own specific mobility and energy. For the first time the influence of triple point (in 2D) and triple line (in 3D) energy and mobility on the grain growth kinetics is shown in detail. The results deviate clearly from normal grain growth kinetics but are in agreement with experimental studies as well as theoretical predictions.

Heterogeneous nucleation theory revisited: Effect of triple junction line energy

This paper will re-consider the basic aspects of solid state classical heterogeneous nucleation theory. In particular it will show how recent experimental work that has been able to estimate grain boundary triple junction line energy can be used to supplement the understanding of the energy balance operating during nucleation. This implies that the energy of the newly created interface needs to be recalculated, assuming that the additional line energy of the line surrounding the precipitate in the plane of the boundary is taken into account. Examples will be given of the application of this revised approach to GB precipitate nucleation of cap-shaped particles of chromium carbide in nickel based alloys. It will be shown that original assumed values of the precipitate-matrix interfacial energy for this transformation have to be revised downward for critical nucleus sizes of less than about 10nm.

On the triple ionization for vacancy in the core level using diffusion Monte Carlo

In this paper, we show that the diffusion Monte Carlo method is able to describe triple ionization energies with the participation of the core electrons. Some states (ground and ionized states) of the ammonia molecule were calculated with trial wave functions constructed by Hartree–Fock and Kohn–Sham orbitals. The results are in good agreement with theoretical data presented in the literature, taking into account the simplicity of the strategy, but the accuracy was influenced by the choice of the orbital in the construction of the trial wave function (hence the quality of the nodal surface), as suggested by Per et al. (J Chem Theory Comput 8:2255–2259, 2012).

Embedded-atom study of low-energy equilibrium triple junction structures and energies

We present an atomistic study of the structures and defect energies of triple junctions (TJs) in polycrystalline materials. A new concept to calculate the excess energy of isolated TJs is proposed and applied to a molecular dynamics (MD) study of iron tricrystals. Line energies of bulk TJs (merging three grain boundaries (GBs)) and surface TJs (merging one grain boundary and two surfaces) are found to be very low. In absolute value they amont to only a few 10−10 Jm−1. Remarkably, defined as a correct excess energy relative to the GBs, the bulk TJ energy is determined to be negative in all studied configurations with an average value of −2.8 × 10−10 Jm−1. These quantitative results are in contrast to various experimental attempts, but they fully agree with simple geometric estimates and broken-bond models, which prompts a re-interpretation of reported measurements.

Theoretical characterization of vanadyl and VO3+ cations in gas phase

We investigate VO2+ and VO3+ ions theoretically. The electronic computations are performed using multi reference configuration interaction approaches in conjunction with the aug-cc-pV5Z basis set. VO2+ potential possesses a Morse-like shape instead of the common volcanic shape since both the charge retaining (V2++O) and charge separating (V++O+) dissociation channels are almost coinciding in energy. Its intense blue color is due to the A2Π–X2Δ transition. We predict VO3+ as metastable. For bound states, we derived a set of accurate spectroscopic parameters. We estimate the adiabatic double and triple ionization energies of VO to be 22.5eV and 50.9eV.

Wide range double photoionisation spectra of N2 and CO2

Using a magnetic bottle time-of-flight electron spectrometer we have measured double photoionisation spectra of N2 and CO2 covering the range from threshold up to the triple ionisation energies. The experiments demonstrate the use of a new asynchronous chopper in eight-bunch mode of the synchrotron radiation source SOLEIL. For CO22+ some broad bands in the Auger spectra are found to have multiple resolved counterparts in the photoionisation spectrum. All the bands in the Auger spectra have counterparts in the photoionisation spectra, where extra bands attributed to triplet states are present. In the spectrum of N22+ we suggest reassignment of one band.

Water and Ethanol Droplet Wetting Transition during Evaporation on Omniphobic Surfaces.

Omniphobic surfaces with reentrant microstructures have been investigated for a range of applications, but the evaporation of high- and low-surface-tension liquid droplets placed on such surfaces has not been rigorously studied. In this work, we develop a technique to fabricate omniphobic surfaces on copper substrates to allow for a systematic examination of the effects of surface topography on the evaporation dynamics of water and ethanol droplets. Compared to a water droplet, the ethanol droplet not only evaporates faster, but also inhibits Cassie-to-Wenzel wetting transitions on surfaces with certain geometries. We use an interfacial energy-based description of the system, including the transition energy barrier and triple line energy, to explain the underlying transition mechanism and behaviour observed. Suppression of the wetting transition during evaporation of droplets provides an important metric for evaluating the robustness of omniphobic surfaces requiring such functionality.

Simultaneous <sup>99m</sup>tc/<sup>111</sup>in spect reconstruction using accelerated convolution-based forced detection monte carlo

Simultaneous multi-isotope Single Photon Emission Computed Tomography (SPECT) imaging has a number of applications in cardiac, brain, and cancer imaging. The major concern however, is the significant crosstalk contamination due to photon scatter between the different isotopes. The current study focuses on a method of crosstalk compensation between two isotopes in simultaneous dual isotope SPECT acquisition applied to cancer imaging using $^{99m}$ Tc and $^{111}$ In. We have developed an iterative image reconstruction technique that simulates the photon down-scatter from one isotope into the acquisition window of a second isotope. Our approach uses an accelerated Monte Carlo (MC) technique for the forward projection step in an iterative reconstruction algorithm. The MC estimated scatter contamination of a radionuclide contained in a given projection view is then used to compensate for the photon contamination in the acquisition window of other nuclide. We use a modified ordered subset-expectation maximization (OS-EM) algorithm named simultaneous ordered subset-expectation maximization (Sim-OSEM), to perform this step. We have undertaken a number of simulation tests and phantom studies to verify this approach. The proposed reconstruction technique was also evaluated by reconstruction of experimentally acquired phantom data. Reconstruction using Sim-OSEM showed very promising results in terms of contrast recovery and uniformity of object background compared to alternative reconstruction methods implementing alternative scatter correction schemes (i.e., triple energy window or separately acquired projection data). In this study the evaluation is based on the quality of reconstructed images and activity estimated using Sim-OSEM. In order to quantitate the possible improvement in spatial resolution and signal to noise ratio (SNR) observed in this study, further simulation and experimental studies are required.

A New Improved Failure Criterion for Salt Rock Based on Energy Method

A non-linear triple shear energy yield criterion for salt rock is presented in this paper. It is the development of the triple shear energy yield criterion, of which the Mohr–Coulomb criterion can be seen as a special case. The main factors affecting the primary strength of salt rock, such as the mean stress and the Lode angle, are considered in the non-linear triple shear energy yield criterion. The non-linear new criterion provides the non-linear change trend of salt strength both in the I 1–J 2 stress space and in the deviatoric plane. Comparative study between the non-linear criterion predictions and experimental results of salt rock shows that the non-linear triple shear energy yield criterion fits quite well with both conventional triaxial test data and the true triaxial test data. For Maha Sarakham salt, the predictive capability of the non-linear triple shear energy yield criterion is clearly better than that of some other criteria used by Sriapai, such as modified Lade criterion, 3-D Hoek, and Brown criterion, Drucker–Prager criterion et al. The availability of the non-linear triple shear energy yield criterion can also be confirmed by comparative analysis between theoretical values and experimental values for non-salt rocks. So the non-linear triple shear energy yield criterion is a general failure criterion for rocks fractured by shear stress.

Reliability and advantages of using non-uniform Chang's attenuation correction method using a CT-based attenuation coefficient map in (99m)Tc-GSA SPECT/CT hepatic imaging.

BackgroundGenerally, attenuation correction is made by incorporating a linear attenuation coefficient, which is based on the attenuation coefficient map (mu-map) created from a computed tomography scan, into the ordered subsets-expectation maximization reconstruction method in non-uniform domains. A non-uniform Chang’s attenuation correction method that uses the mu-map created from a computed tomography image that was made after reconstruction has been performed is currently available. The purpose of this study was to determine the usefulness of the non-uniform Chang’s attenuation correction method in 99mTc-galactosyl human serum albumin diethylenetriamine pentaacetic acid single photon emission computed tomography/computed tomography imaging.MethodsSingle photon emission computed tomography/computed tomography imaging was performed in phantoms with 99mTc water solutions and in a clinical study of 20 donors in living liver tissue transplantation. Attenuation correction was then performed in the reconstructed single photon emission computed tomography images with the non-uniform Chang’s method and ordered subsets-expectation maximization attenuation correction methods with triple energy window scatter correction. Root mean square error values were used for assessment of the image uniformity, and we evaluated the absolute radioactivity in liver parts in the phantoms and those in the donors who had a normal liver function.ResultsThe values of root mean square error on the non-uniform Chang’s attenuation correction images were lower than those on ordered subsets-expectation maximization attenuation correction images for both the phantoms and the 20 donors. The difference between the true and estimated radioactivity in the non-uniform Chang’s attenuation correction method was smaller than that in the ordered subsets-expectation maximization attenuation correction methods in the phantom study.ConclusionsThe non-uniform Chang’s attenuation correction is considered to be superior to the ordered subsets-expectation maximization attenuation correction in the assessment of absolute liver radioactivity and liver image uniformity on 99mTc-galactosyl human serum albumin diethylenetriamine pentaacetic acid single photon emission computed tomography/computed tomography imaging.

X-ray beam design for multi-energy imaging with charge-integrating detector: A simulation study

Multi-energy X-ray imaging systems have been widely used for clinical examinations. In order to enhance the imaging quality of these X-ray systems, a dual-energy system that can obtain specific information has been developed in order to discriminate different materials. Although the dual-energy system shows reliable performance for clinical applications, it is necessary to improve the method in order to minimize radiation dose, reduce projection error, and increase image contrast. The purpose of this study is to develop a triple energy technique that can discriminate three materials for the purpose of enhancing imaging quality and patient safety. The X-ray system tube voltage was varied from 40 to 90kV, and filters (that can generate three X-ray energies) were installed, consisting of pure elemental materials in foil form (including Al, Cu, I, Ba, Ce, Gd, Er, and W). The X-ray beam was evaluated with respect to mean energy ratio, contrast variation ratio, and exposure efficiency. In order to estimate the performance of the suggested technique, Monte Carlo was conducted, and the results were compared to the photon-counting method. As a result, the density maps of iodine, aluminum, and polymethyl methacrylate (PMMA) using the X-ray beam were more accurate in comparison to that obtained with the photon-counting method. According to the results, the suggested triple energy technique can improve the accuracy of the determination of thickness of density. Moreover, the X-ray beam could reduce unnecessary patient dose.

Thermodynamics and Kinetics of 1D Structural Elements and Stability of Nanocrystalline Materials

Grain boundary triple junctions are the structural elements of a polycrystal. Recently it was recognized that they can strongly impact the microstructural evolution, and therefore there engender new opportunities to control and to design the grain microstructure of fine-grained and nanocrystalline materials due to their effect on recovery, recrystallization and grain growth. The measurement of triple junction energy and mobility is thus of great importance. The line energy of a triple junction constructs an additional driving force of grain growth. Taking the triple line energy into account, a modified form of the Zener force and the Gibbs-Thomson relation can be derived to reveal the influence of the triple line energy on second phase particles and the change of the equilibrium concentration of vacancies in the vicinity of voids at a grain boundary. The impact of triple junctions on the sintering of nanopowders is discussed. The role of “grain boundary - free surface” triple lines in the adhesive contact formation between spherical nanoparticles is considered. It is shown that there is a critical value of the triple line energy above which the nanoparticles do not stick together. Based on this result, a new nanoparticle agglomeration mechanism is proposed, which accounts for the formation of large agglomerates of crystallographically aligned nanoparticles during the nanopowder processing.

Communication: The performance of non-iterative coupled cluster quadruples models.

We compare the numerical performance of various non-iterative coupled cluster (CC) quadruples models. The results collectively show how approaches that attempt to correct the CC singles and doubles energy for the combined effect of triple and quadruple excitations all fail at recovering the correlation energy of the full CC singles, doubles, triples, and quadruples (CCSDTQ) model to within sufficient accuracy. Such a level of accuracy is only achieved by models that make corrections to the full CC singles, doubles, and triples (CCSDT) energy for the isolated effect of quadruple excitations of which the CCSDT(Q-3) and CCSDT(Q-4) models of the Lagrangian-based CCSDT(Q-n) perturbation series are found to outperform alternative models that add either of the established [Q] and (Q) corrections to the CCSDT energy.

Studying the influence of triple junction energy and mobility on annealing processes

The kinetics of grain growth in nanocrystalline two-dimensional polycrystals and thin films can be controlled by the triple junctions of the microstructure. In the present work the influence of energy and mobility of grain boundaries and their junctions on annealing is investigated by analytic theories and modified Monte Carlo Potts model simulations. To that aim each structural feature of a polygonal grain is assigned its own specific energy and finite mobility, which results in four different limiting cases of self-similar growth kinetics each characterized by its own metrical and topological properties.

Effect of phenylamine moiety on the structure, optical properties, and phosphorescence efficiencies of some red-emitting iridium(III) complexes: A theoretical study

Abstract Quantum-chemistry methods are used to investigate the effect of phenylamine chromophore on the electronic structure, optical properties, and phosphorescence efficiencies of a series of fac -iridium(III) complexes, Ir-(g0) 3 (1) , meta-substituted Ir compounds [Ir-(g0) 2 -(g1) 1 ] (1a) , [Ir-(g0) 1 -(g1) 2 ] (1b) , [Ir-(g1) 3 ] (1c) and para-substituted Ir compounds [Ir-(g0) 2 -(g1′) 1 ] (2a) , [Ir-(g0) 1 -(g1′) 2 ] (2b) , [Ir-(g1′) 3 ] (2c) , where g0 = l -phenylisoquinolinato, g1 = 4-(isoquinolin-1-yl)- N , N -diphenylbenzenamine, g1′ = 3-(isoquinolin-1-yl)- N , N -diphenylbenzenamine. The calculations show that introduction of phenylamine chromophore at meta position of phenyl ring ( 1a – 1c ) slightly changes the ground-states geometries but largely increases the energy of HOMO and decreases IP values hence improves the ability of hole injection, which is consistent with the experimental report. The introduction of diphenylamine substitutions on the para position ( 2a – 2c ) is effective for extending the π-electron delocalization, which results in strengthening metal-ligand bond and dramatically increasing the HOMO energy. More important, the 2a – 2c have enhanced metal-to-ligand charge transfer 3 MLCT participation in the phosphorescent spectra, decreased the singlet-triplet splitting energy (Δ E S1–T1 ), as well as dramatically small energy differences between the highest occupied orbitals splitting (Δdd occ ) and large lowest unoccupied d-orbitals splitting (Δdd*) at the both S 0 and T 1 geometries, these account for the quantum yield and efficiency of phosphorescence. The calculated ionization potentials (IPs), electronic affinities (EAs), and reorganization energy ( λ ) confirm that the hole and electron injection and transfer ability were enhanced by importing the diphenylamine. Furthermore, based on the analyses of triple energy differences between host and guest, charge carrier mobility, optical overlap, it is found that these Ir complexes maybe good guest materials in CBP. Thus, the introduction of phenylamine at para position is effective approach to obtain highly efficient red phosphorescent emitters.

SU-C-201-06: Utility of Quantitative 3D SPECT/CT Imaging in Patient Specific Internal Dosimetry of 153-Samarium with GATE Monte Carlo Package

Purpose: Patient-specific 3-dimensional (3D) internal dosimetry in targeted radionuclide therapy is essential for efficient treatment. Two major steps to achieve reliable results are: 1) generating quantitative 3D images of radionuclide distribution and attenuation coefficients and 2) using a reliable method for dose calculation based on activity and attenuation map. In this research, internal dosimetry for 153-Samarium (153-Sm) was done by SPECT-CT images coupled GATE Monte Carlo package for internal dosimetry. Methods: A 50 years old woman with bone metastases from breast cancer was prescribed 153-Sm treatment (Gamma: 103keV and beta: 0.81MeV). A SPECT/CT scan was performed with the Siemens Simbia-T scanner. SPECT and CT images were registered using default registration software. SPECT quantification was achieved by compensating for all image degrading factors including body attenuation, Compton scattering and collimator-detector response (CDR). Triple energy window method was used to estimate and eliminate the scattered photons. Iterative ordered-subsets expectation maximization (OSEM) with correction for attenuation and distance-dependent CDR was used for image reconstruction. Bilinear energy mapping is used to convert Hounsfield units in CT image to attenuation map. Organ borders were defined by the itk-SNAP toolkit segmentation on CT image. GATE was then used for internal dose calculation. The Specific Absorbed Fractionsmore » (SAFs) and S-values were reported as MIRD schema. Results: The results showed that the largest SAFs and S-values are in osseous organs as expected. S-value for lung is the highest after spine that can be important in 153-Sm therapy. Conclusion: We presented the utility of SPECT-CT images and Monte Carlo for patient-specific dosimetry as a reliable and accurate method. It has several advantages over template-based methods or simplified dose estimation methods. With advent of high speed computers, Monte Carlo can be used for treatment planning on a day to day basis.« less

A thermally stable imidazole type ligand based Be complex as a triplet host material of green phosphorescent organic light emitting diodes

A 2-(4,5-dimethyl-1-phenyl-imidazol-2-yl)phenol ligand based Be complex, beryllium 2-(4,5-dimethyl-1-phenyl-imidazol-2-yl)phenolate (BePhIm), was investigated as a thermally stable host material of green phosphorescent organic light-emitting diodes (PHOLEDs). BePhIm was developed as a host material to have high triplet energy, thermal stability and balanced charge density. The triple energy of BePhIm was 2.73eV and the glass transition temperature was 181°C. Maximum quantum efficiency of the BePhIm based green PHOLEDs was 25.9%, which is better than any other quantum efficiency reported in green PHOLED using Be complexes as the host material.

Determination of energy windows for the triple energy window scatter correction method in I-131 on a Siemens SYMBIA gamma camera: a GATE simulation study

Image correction for scattered photons is important for the quantification of gamma-camera imaging using I-131. Many previous studies have addressed this issue but none have compared scattered photon fractions of I-131 with varying energy windows, to determine optimal main- and sub-energy windows for the implementation of TEW correction in I-131 imaging. We assessed the scattered photon fractions and determined the optimal main- and sub- energy windows for TEW in I-131 using a Siemens SYMBIA T2 SPECT/CT using a Monte Carlo method (GATE simulation). To validate the GATE simulation code, we compared the spatial resolutions obtained experimentally and from GATE simulation, for I-123 and Tc-99m. A high-energy general purpose (HE) collimator was used to assess the scattered photon fractions measured with the I-131 radioisotope placed at eight different field-of-view locations in a water phantom (diameter 16 cm, length 32 cm), and at the center in air. To implement the TEW (triple energy window) method, two different main-energy window widths (15 and 20%) and two different sub-energy window widths (3 and 5 keV) were used. The experimental measurement and simulation results exhibited a similar pattern with < 15% difference in spatial resolution with increasing distance. The I-131 scatter fraction with 15% of the main-energy window and 5 keV sub-energy windows was similar to the ``goldstandard'' scatter fraction. Main- and sub-energy window selection for the TEW correction in I-131 is important to avoid over- or under-correction in the scatter fraction. A 15% of main energy window with 5 keV sub-energy windows were found to be optimal for implementation of the TEW method in I-131. This result provides the optimal energy window for I-131 scintigraphy data and will aid the quantification of I-131 imaging.

Efforts to Improve the Images from &amp;lt;sup&amp;gt;67&amp;lt;/sup&amp;gt;Ga Whole-Body Scintigraphy

The acquisition method for planar 67Ga imaging has hardly changed for 30 years. In this study, in order to improve image quality and diagnostic accuracy, we take steps to optimize the acquisition method, and to choose a scatter correction. First, we acquired individual images from the 93 keV, 185 keV, and 300 keV photopeak; then the images were added together and compared to the individual images. Second, we compared results from a low-medium-energy (LME) collimator with those from a conventional medium-energy (ME) collimator. Also, we examined whether to combine the data from all three of the usual window locations (set about 93 keV, 185 keV, and 300 keV) or to use the data from only two. Third, we compared results from a conventional photopeak ± 10％ window with those from a photopeak ± 9 keV window. Fourth, for scatter correction we compared results using the triple energy window (TEW) method with those using the multi-photopeak dual window (MDW) method. The phantoms studied were cold rods in a uniform background, and hot spheres within a cylinder containing uniformly radioactive water. The clinical study involved 22 patients with lung lesions. By the comparison by the contrast ratio in cold rods phantom, 15.6% is improved in LME (2 peaks) than ME (3 peaks), and 3.2% is improved in photopeak ± 9 keV than photopeak ± 10%, 10.2% is improved in TEW than MDW. However, the TEW scatter correction method recognized unstable to the contrast ratio in a clinical study. In addition, a body outline might disappear.