MeV X-ray Research Articles

A method of evaluating the relative light yield of ST401 irradiated by pulsed neutron

High speed imaging technique is an effective method to test the information about pulsed neutron source. Imaging system is usually composed of a pinhole, a scintillator, an image intensifier and a charge-coupled device (CCD) camera. ST401 plastic scintillator is widely used to convert the neutron image into visible light image since it has features of high conversion efficiency and fast time response. When testing a pulsed neutron source of wide energy spectrum, we should evaluate the light yields of ST401 irradiated by neutrons with different energies and make the CCD camera exposed to the light appropriately. A 0.3 MeV pulsed X-ray source is often used to calibrate the imaging system because of its low cost than the D-T fusion neutron source. In this work, a method of evaluating the relative light yield of ST401 irradiated by 0.1-16 MeV neutron to 0.3 MeV X-ray is proposed.Geant4 Monte Carlo software is used to simulate the transport performances of neutrons and X-rays. The software package can simulate the transport process of photons. But the conversion factor of ray energy deposition into photons is unknown. It is difficult to calculate the number of photons generated in ST401 accurately. In this article, we calculate the relative light yield according to the energy of charged particles produced in ST401. Firstly, all information about the particle type, energy deposition, kinetic energy is monitored on event-by-event basis in GEANT4. Secondly, the complete history of the tracks is then used to calculate the light output from the scintillator according to the neutron response functions. Thirdly, the light output caused by charged particles going out of ST401 is deducted. Ratios of average light yield of 1 mm, 3 mm, 5 mm, 1 cm, 2 cm, 3 cm, 5 cm thick ST401 irradiated by 0.1-16 MeV neutron to 0.3 MeV X-ray are given. To confirm the correctness of the simulated result, validation experiment is carried out on IVA pulsed X-ray source and SGIII pulsed neutron source. The simulated ratio of average light yield of ST401 irradiated by one single 14 MeV neutron to 0.3 MeV X-ray has a discrepancy of less than 10% compared with the measured value. Compared with the results of experiment conducted on a constant current source, the simulated results have a maximum discrepancy of less than 44%. If CCD camera exposure 10%-90% of the full scale, the image will have high contrast and information loss can be avoided. According to the simulated results and the neutron yield, exposure can be easily set to be 60% of the full scale by adjusting the gain of the image intensifier. Assume that the simulated results have a 44% discrepancy, the actual exposure will be in a range of 34%-86% of the full scale. Underexposure and overexposure can be avoided by presetting the imaging system sensitivity appropriately based on the simulated results. It implies that the method proposed is effective in predicting the imaging system response to pulsed neutron with wide energy spectrum.

Determining the focal spot limit of 1 MeV X-ray targets: Monte Carlo simulation of the point spread function

Among all microfocus X-ray tubes, 1MeV has remained a “gray zone” despite its universal application in radiation therapy and non-destructive testing. One challenge existing in fabricating 1MeV microfocus X-ray tubes is beam broadening inside metal anodes, which limits the minimum focal spot size a system can obtain. In particular, a complete understanding of the intrinsic broadening process, i.e., the point-spread function (PSF) of X-ray targets is needed. In this paper, relationships between PSF and beam energy, target thickness and electron incidence angle were investigated via Monte Carlo simulation. Focal spot limits for both transmission- and reflection-type tungsten targets at 0.5, 1 and 1.5MeV were calculated, with target thicknesses ranging from 1μm to 2cm. Transmission-type targets with thickness less than 5μm could achieve micrometer-scale spots while reflection-type targets exhibited superiority for spots larger than 100μm. In addition, by demonstrating the spot variation at off-normal incidence, the role of unidirectional beam was explored in microfocus X-ray systems. We expect that these results can enable alternative designs to improve the focal spot limit of X-ray tubes and benefit accurate photon source modeling.

Comparison of bactericidal efficiency of 7.5 MeV X-rays, gamma-rays, and 10 MeV e-beams

Abstract This study was performed to verify the feasibility of 7.5 MeV X-rays for food pasteurization through a comparison of the bactericidal efficiency with those of other sources for selected bacterial pathogens. No significant differences were observed between the overall bactericidal efficiency for beef-inoculated pathogens based on the uncertainty of the absorbed dose and variations in bacterial counts. This result supported that all three irradiation sources were effective for inactivation of food-borne bacteria and that 7.5 MeV X-rays may be used for food pasteurization.

165 - Comparative evaluation of the in vitro the comet assay for the detection of genotoxic effects of 60 MeV protons and X-ray radiation

165 - Comparative evaluation of the in vitro the comet assay for the detection of genotoxic effects of 60 MeV protons and X-ray radiation

Congenital Ewing's Sarcoma/Primitive Neuroectodermal Tumor of the Upper Extremity.

Dear Editor, The patient was a female newborn, 3200 g in weight, 50 Cm in length, who presented at birth with a firm mass on the left upper arm, measuring 25 × 16 × 45 mm in size. Physical examination revealed a non-movable mass with firm consistency and mild tenderness on the left upper arm. Family and maternal histories were unnoteworthy, and the laboratory examination was normal. An excisional biopsy of the mass was performed and the histopathological findings of the excised lesion were ES/PNET. Immunohistochemistry was positive for CD99, NSE, PCK, desmin, and negative for CK. In enhanced chest CT, abdominal ultrasonography, and whole body bone scan no evidence of abnormality or metastasis was detected. Bone marrow biopsy and further treatment were refused by her parents. Unfortunately, the sarcoma recurred one year later. Seven cycles of VIDE regimen (Vincristine 0.25 mg d1; Ifosfamide 500 mg d1-4; Doxorubicin 3.5 mg d1-4; Teniposide 50 mg d1, 25 mg d2-4) was administered. After radiation therapy (3040cGy/19 fractions, 6 MeV electrons), the patient underwent autologous stem cell transplantation and achieved a complete remission. Two years later, the patient came to our institution presenting with a subcutaneous mass near the area of surgical scar on the left upper arm. The ultraphonic revealed several hypoechoic nodules between the skin and subcutaneous fat layer on the left upper arm, the biggest one measured 15 × 5mm in size. X-ray (Panel A) showed no adjacent humerus destruction. Magnetic Resonance Imaging showed several nodules on the shallow surface of biceps muscle of the left arm with slight enhancement and marked swelling of the surrounding soft tissue (Panel B, C, arrow). Chest CT scan and whole body bone scan were normal. Subsequent excisional biopsies were performed on 18/11/2013, and the postoperative pathologic results were Ewing’s sarcoma. The patient was treated by a course of three-dimensional conformal radiotherapy (3D-CRT) after surgery. Dose of external irradiation was 4680cGy/26 fractions (6 MeV X-ray) in 30 days. The patient is alive 20 months after the second relapse. ES and PNET share common antigenic profiles, cytogenic aberrations and proto-oncogene expression which are derived from the same primordial bone marrow-derived mesenchymal stem cell (1). At the molecular level, ES/PNET is characterized by chromosomal translocations that fuse the EWSR1 gene to some members of the ETS family of transcription factors, being FLI1 the most frequently implicated [t (11; 22) (q24; q12)] (2). The incidence of these tumors in early childhood is rare, accounting for less than 10 cases per million each year (3), and the incidence in newborns is exceedingly rare. Wong et al reported 1975 patients with Ewing’s sarcoma, only 39 (2.0%) were diagnosed at < 12 months of age (4). ES/PNET with a slight male predominance occur predominantly in primarily white and Hispanic patients; however, these tumors are extremely rare in individuals of African or Asian origin (2). ES/PNET account for approximately 10% of primary malignant bone tumors and mainly affect the long bones (47%), pelvis or ribs (5). While 30% are seen in an extraskeletal location of the soft tissues, 5% occurred in extremities among these extraskeletal Ewing’s sarcomas (6, 7). Manifestation in extraskeletal location of the soft tissues of extremities rarely occurs and this would appear to be the first description of a congenital ES/PNET arising in the soft tissue of upper extremity. Multiagent systemic therapy for localized ES/PNET achieved a 5-year survival of approximatly 70 - 75% (8-10). The similarity in survival between older and younger patients with Ewing sarcoma was reported in literature (11). A study including 2202 ES/PNETs demonstrated that extraskeletal ES/PNETs have a superior prognosis compared with skeletal Ewing sarcoma. About 30 – 40% of patients suffer from recurrent tumors and have a very poor prognosis (12). The 5-year survival following recurrence of these patients is approximately 10 – 15%, while it was 7% for those whose disease recurred within 2 years (13). In our case of disease recurrence after surgery, the patient was treated with multiagent chemotherapy, stem cell transplantation and aggressive surgical treatment, and is still surviving.

Proton-induced x-ray fluorescence CT imaging.

To demonstrate the feasibility of proton-induced x-ray fluorescence CT (pXFCT) imaging of gold in a small animal sized object by means of experiments and Monte Carlo (MC) simulations. First, proton-induced gold x-ray fluorescence (pXRF) was measured as a function of gold concentration. Vials of 2.2 cm in diameter filled with 0%-5% Au solutions were irradiated with a 220 MeV proton beam and x-ray fluorescence induced by the interaction of protons, and Au was detected with a 3 × 3 mm(2) CdTe detector placed at 90° with respect to the incident proton beam at a distance of 45 cm from the vials. Second, a 7-cm diameter water phantom containing three 2.2-diameter vials with 3%-5% Au solutions was imaged with a 7-mm FWHM 220 MeV proton beam in a first generation CT scanning geometry. X-rays scattered perpendicular to the incident proton beam were acquired with the CdTe detector placed at 45 cm from the phantom positioned on a translation/rotation stage. Twenty one translational steps spaced by 3 mm at each of 36 projection angles spaced by 10° were acquired, and pXFCT images of the phantom were reconstructed with filtered back projection. A simplified geometry of the experimental data acquisition setup was modeled with the MC TOPAS code, and simulation results were compared to the experimental data. A linear relationship between gold pXRF and gold concentration was observed in both experimental and MC simulation data (R(2) > 0.99). All Au vials were apparent in the experimental and simulated pXFCT images. Specifically, the 3% Au vial was detectable in the experimental [contrast-to-noise ratio (CNR) = 5.8] and simulated (CNR = 11.5) pXFCT image. Due to fluorescence x-ray attenuation in the higher concentration vials, the 4% and 5% Au contrast were underestimated by 10% and 15%, respectively, in both the experimental and simulated pXFCT images. Proton-induced x-ray fluorescence CT imaging of 3%-5% gold solutions in a small animal sized water phantom has been demonstrated for the first time by means of experiments and MC simulations.

Density of hydroxyl radicals generated in an aqueous solution by irradiating carbon-ion beam.

The density of hydroxyl radicals (·OH) produced in aqueous samples by exposure to X-ray or carbon-ion beams was investigated. The generation of ·OH was detected by the electron paramagnetic resonance (EPR) spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trapping agent. When the concentration of DMPO is in excess of the generated ·OH, the production of DMPO-OH (spin-trapped ·OH) should be saturated. Reaction mixtures containing several concentrations (0.5-1685 mM) of DMPO were then irradiated by a 32 Gy 290 MeV carbon-ion beam (C290-beam) or X-ray. C290-beam irradiation was performed at the Heavy-Ion Medical Accelerator in Chiba (HIMAC, National Institute of Radiological Sciences, Chiba, Japan), applying different linear energy transfers (LET) (20-169 keV/µm). The amount of DMPO-OH in the irradiated samples was detected by EPR spectroscopy. The generation of DMPO-OH increased with the concentration of initial DMPO, displayed a shoulder around 3.3 mM DMPO, and reached a plateau. This plateau suggests that the generated ·OH were completely trapped. Another linear increase in DMPO-OH measured in solutions with higher DMPO concentrations suggested very dense ·OH generation (>1.7 M). Generation of ·OH is expected to be localized on the track of the radiation beam, because the maximum concentration of measured DMPO-OH was 40 µM. These results suggested that both sparse (≈3.3 mM) and dense (>1.7 M) ·OH generation occurred in the irradiated samples. The percentage of dense ·OH generation increased with increasing LET. Different types of dense ·OH generation may be expected for X-ray and C290-beams.

On-site nondestructive inspection by upgraded portable 950 keV/3.95 MeV X-band linac x-ray sources

We have developed and upgraded portable 950 keV/3.95 MeV X-band (9.3 GHz) linac x-ray sources for on-site nondestructive testing (NDT) for social and industrial infrastructures. We integrated the hardware devices as well as software systems. For the hardware, we established all designed parameters including x-ray intensities of 0.05/2 Gy min−1 at 1 m for 950 keV/3.95 MeV systems, respectively. Concerning the software, we adopted the wavelet analysis for enhanced image contrast and partial angle computed tomography (CT) for a small region of interest. The wavelet analysis is effective to reduce scattered low energy x-ray noise in addition to using physical filters and collimators. The partial CT is inevitable to reconstruct an inner reinforced iron tube in concrete. We successfully performed on-site inspection three times, namely of a nitrogen acid distillation tower, a reinforced concrete pier and a large sample cut from a bridge. We obtained the x-ray images of the inner tube, determined the sizes of reinforced iron parts and evaluated the mechanical tolerance. Moreover, we are developing a new x-ray camera specified for MeV x-rays used for NDT of heavy objects. Then, our system will become a self-consisting and specialized high energy x-ray on-site inspection system. We are going to promote an application to NDT of social and industrial infrastructures in Japan and around the world.

Microbicidal effectiveness of X-rays used for sterilization purposes

The radiation response of spores of Bacillus pumilus was examined for irradiation with 5–7 MeV X-ray at commercial sterilization facilities. The response was found to be the same as that for irradiation with cobalt 60 photons, 10 MeV electrons and low energy electrons at 100 and 80 keV.

Monte Carlo Simulation of Phytosanitary Irradiation Treatment for Mangosteen Using MRI-based Geometry

Purpose: Phytosanitary irradiation treatment can effectively control regulated pests while maintaining produce quality. The objective of this study was to establish the best irradiation treatment for mangosteen, a popular tropical fruit, using a Monte Carlo simulation. Methods: Magnetic resonance image (MRI) data were used to generate a 3-D geometry to simulate dose distributions in a mangosteen using a radiation transport code (MCNP5). Microsoft Excel with visual basic application (VBA) was used to divide the image data into seed, flesh, and rind. R adiation energies used for the simulation were 10 MeV (high-energy) and 1.35 MeV (low-energy) for the electron beam, 5 MeV for X-rays, and 1.25 MeV for gamma rays from Co-60. Results: At 5 MeV X-rays and 1.25 MeV gamma rays, all areas (seeds, flesh, and rind) were irradiated ranging from 0.3 ~ 0.7 kGy. The average doses decreased as the number of fruit increased. For a 10 MeV electron beam, the dose distribution was biased: the dose for the rind where the electrons entered was 0.45 ± 0.03 kGy and the other side was 0.24 ± 0.10 kGy. Use of an electron kinetic energy absorber improved the dose distribution in mangosteens. For the 1.35 MeV electron beam, the dose was shown only in the rind on the irradiated side; no significant dose was found in the flesh or seeds. One rotation of the fruit while in front of the beam improved the dose distribution around the entire rind. Conclusion: These results are invaluable for determining the ideal irradiation conditions for phytosanitary irradiation treatment of tropical fruit.

Radiation-induced telomere length variations in normal and in Nijmegen Breakage Syndrome cells

Purpose: The meiotic recombination protein 11 (MRE11), radiation sensitive 50 (RAD50) and nibrin (NBN) are members of the MRE11/RAD50/NBN (MRN) complex which plays a fundamental role in the double-strand break damage response, including DNA damage sensing, signalling and repair after exposure to ionizing radiations. In addition the MRN complex is involved in the mechanisms regulating telomere length maintenance. Based on our previous results indicating that, in contrast to X-rays, high linear energy transfer (LET) radiations were able to elongate telomeres, we investigated the behavior of cells mutated in components of the MRN complex after exposure either to 62 MeV carbon-ions (50 keV/μm, at cell surface) or X-rays.Materials and methods: Epstein Barr Virus (EBV)-transformed lymphoblastoid cell lines (LCL) established from normal, heterozygous for the NBN gene, homozygous for either mutant/deleted NBN, RAD50 or ataxia telangiectasia mutated (ATM) genes were irradiated with 4 Gy, with telomere length being evaluated 24 h later or in time course-experiments up to 15 days later. The induction of telomeric sister chromatid exchanges (T-SCE) was measured as a hallmark of homologous directed recombinational repair.Results: NBN and RAD50 mutated cells failed to elongate telomeres that instead occurred in the remaining cell lines as a response only to high-LET irradiation. Also, a kinetic study with 0.5–4 Gy up to 15 days from irradiation confirmed that NBN gene was indispensable for telomere elongation. Furthermore, such an elongation, was accompanied by an increased frequency of sister chromatid exchanges at telomeres (T-SCE). In contrast, the induction of genomic sister chromatid exchanges (G-SCE) occurred for carbon-ions irrespective of NBN gene status.Conclusions: We speculate that the MRN is necessary to process a subclass of high-LET radiation-induced complex DNA damage through a recombinational-repair mediated mechanism which in turn is responsible for telomere elongation

방사선에 조사된 쥐 간에서 블루베리의 방사선방호효과

방사선은 간 기능에 심각한 장애를 준다. 블루베리는 Vit A, Vit C, Vit E, 엽산, <TEX>${\beta}$</TEX>-카로티노이드 및 안토시아닌을 포함하고 있는 과일이다. 본 연구의 목적은 블루베리의 간 기능의 보호 효과를 평가하는 것이다. 4 Gy (Linac 6 Mev)를 X 선 장치를 사용하여 조사하였고, 각 실험군 당 7 마리로 쥐를 사용하였다. 간기능을 보기 위해 TP, ALB, GLOB, ALT, ALKP 그리고 CHOL 등을 측정하였다. 본 실험을 통해 블루베리가 방사선으로 인한 간 기능의 손상에 대해 방호효과가 없다는 것을 관찰 할 수 있었다. 그러나 통계적으로 ALB (P> 0.01)와 ALT (P> 0.1)는 유의성이 있다고 나타났다. 결론적으로, 블루베리는 방사선으로 인해 유발되어지는 간 기능의 손상에 대해 방호효과가 없다. Radiation were seriously damaged on liver functions. Blueberry was fruits that contains Vit A, Vit c, Vit E, follic acid, <TEX>${\beta}$</TEX>-carotene, and anthocyanin. The purpose of this study was to evaluate the protection effects of blueberry the liver functions. Irradiation dose was used to 4 Gy (Linac 6 Mev) X-ray Treatment device Experiment animals was used to 7 rats in each groups. It was investigated liver functions that contains TP, ALB, GLOB, ALT, ALKP and CHOL. We showed that Blueberry was not recovery effects on radiation-induced liver functions. But, Statistically significant value was showed ALB (p>0.01) and ALT (p>0.1). It was concluded that blueberry was not used to recovery materials on radiation-induced liver functions.

Observation of neutrons in the interaction of high intensity laser pulses with solid targets

We report an experimental study on fusion neutron generation from deuterated polyethylene (CD2)n target irradiated by 400 mJ, 45 femtosecond laser pulses focused to an intensity >10 18 W/cm 2 .T he fusion neutron signal has been detected using a CR-39 detector, a bubble detector, and also confirmed by a neutron time of flight detector. In addition, substantial bremsstrahlung X-ray radiation of MeV energy was also observed. These MeV X-rays have been used to trigger (, n) reaction in Be and Cu targets and the resulting photo-neutrons were detected on a BF3 and a bubble detector.

Simulations of Dynamic Laser/Plasma X-Ray Production

Intense laser beams focused onto thin high-atomic-number targets can generate short intense bursts of MeV X-rays from a small area of the target. Such systems are being developed as short-pulse point-projection X-ray sources for imaging high-density objects. Here, large-scale (400-million macroparticles and 15-million grid cells) 3-D particle-in-cell simulations are described that model the dynamic interaction between the laser beam, a blowoff plasma layer, and the solid-density target. The simulations self-consistently treat the nonlinear interaction between the incident laser pulse and the blowoff plasma layer where a relativistic electron beam is generated. This beam propagates into the solid-density high-atomic-number target where MeV bremsstrahlung is generated. The model tracks the generation, propagation, and self-absorption of radiation in the blowoff plasma, target, and beyond. Radiation production (fluence and energy spectrum) is characterized in the simulations as a function transverse target size, laser-injection angle, and laser energy. The simulated X-ray fluence for the case of a 45 °-angle-of-incidence 100-J 0.5-ps laser pulse with a 6- μm FWHM focus produces a peak dose in excess of 0.2 rad from a 10-μm-thick square gold target, consistent with experimental measurements.

Development of a High Resolution X-Ray CT Technique for Irradiated Fuel Pellets

A nondestructive method making use of X-ray computer tomography (X-ray CT) has been applied to post irradiation examinations (PIEs) of fast breeder reactor (FBR) fuel assemblies. In the X-ray CT system, a 12 MeV X-ray pulse was used in synchronization with switching on the detector to minimize the effects of gamma ray emissions from the irradiated fuel assemblies. This technique enables a clear cross section CT images of the irradiated fuel assembly to be obtained.

Compatibility study of Ti and Ge2Sb2Te5 for phase-change memory applications

In this study, the kinetics of titanium–Ge2Sb2Te5 chalcogenide compound formation has been investigated by transmission electron microscopy, MeV helium-ion backscattering spectrometry, X-ray diffraction and secondary ion mass spectrometry. Two sets of samples have been used, one with titanium on a Ge2Sb2Te5 film and the other with a reverse structure. To induce the compound formation, isothermal experiments were carried out at various temperatures. It has been found that titanium induces the dissociation of the chalcogenide layer and the formation of TiTe2 compound. In both the samples, the growth of TiTe2 is kinetically controlled with an activation energy of 0.9±0.1 eV. In excess of titanium atoms with respect to tellurium, the dissociation of what is left in the original chalcogenide proceeds by the formation of TiGe x compound, leaving antimony and eventually germanium grains.

ROS enhancement by silicon nanoparticles in X-ray irradiated aqueous suspensions and in glioma C6 cells

The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spec- troscopy before and after irradiation to evaluate the effect of high energy radiation on their structure. The total concentration of O2 •- /HO2 • ,H O • , and H2O2 generated upon 4-MeV X-ray irradiation of 6.4 lM silicon nanoparticle aqueous suspensions were on the order of 10 lM per Gy, ten times higher than that obtained in similar experiments but in the absence of particles. Cytotoxic 1 O2 was generated only in irradi- ation experiments containing the particles. The particle surface became oxidized to SiO2 and the luminescence yield reduced with the irradiation dose. Changes in the surface morphology did not affect, within the experi- mental error, the yields of ROS generated per Gy. X-ray irradiation of glioma C6 cell cultures with incorporated silicon nanoparticles showed a marked production of ROS proportional to the radiation dose received. In the absence of nanoparticles, the cells showed no irradia- tion-enhanced ROS generation. The obtained results indicate that silicon nanoparticles of\5 nm size have the potential to be used as radiosensitizers for improv- ing the outcomes of cancer radiotherapy. Their capa- bility of producing 1 O2 upon X-ray irradiation opens

Development of High Resolution X-Ray CT Technique for Highly-Radioactive Material

ABSTRACTIn order to observe the structural change in the interior of irradiated fuel assembly, the non-destructive post irradiation examination technique using X-ray computer tomography (X-ray CT) was developed.In this X-ray CT system, the 12 MeV X-ray pulses were used in synchronization with the switch-in of the detector in order to minimize the effects of the gamma ray emissions from the irradiated fuel assembly then clear cross section CT image of irradiated fuel assembly could be successfully obtained. Also, this non-destructive technique can be applied to observe the inner condition of the high radioactive materials such as a radioactive waste.

Ion Beam (RBS) and XRF Analysis of Metal Contacts Deposited on CdZnTe and CdTe Crystals

Rutherford Backscattering Spectrometry (RBS) using 6 MeV alpha particles and X-Ray Fluorescence (XRF) with a Pd-anode X-Ray generator were performed to characterize Au and Pt contacts deposited by electroless technique and thermal evaporation on differently treated surfaces of CdZnTe and CdTe crystals. The aim of this study is to understand and improve the structure of the material-electrode interface. The thickness, the stoichiometry and the concentration profiles of platinum, gold, cadmium, zinc, tellurium and oxygen present at the surface layers were determined. The distribution of Cd deficiency at the interface layers was profiled using simulations and showed complex profiles in the samples, which can greatly affect the electrical quality of the detectors.

A Reconstruction Method for Dual High-Energy CT With MeV X-Rays

Dual-energy computed tomography (DECT) allows one to obtain both density and atomic number and thus can provide information about material composition of scanned objects. In this paper, we extend a basis material decomposition method for high energy X-ray DECT used in cargo inspection. It differs from conventional DECT reconstruction methods by pair-production effect coming into play in the reconstruction. The pair-production does not happen for DECT in low energy level (lower than 1 MeV). The decomposition error of the basis material model and its applicability in the high-energy level are analyzed in this paper. A reconstruction method based on this model is proposed to reconstruct both the atomic number <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Z</i> and the electron density ρ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</i> images for a high-energy DECT. The method is validated by a numerical simulation and a practical experiment on a cargo inspection system. Results show that the proposed reconstruction method is strongly grounded on physics and feasible for high-energy DECT in material discrimination, especially for cargo inspections. The advantages and limitations of the high-energy DECT, as well as possible improvements for future work are discussed in this paper.