Fast X-ray imaging beamline at SSRF

The fast X-ray imaging beamline(BL16U2)at Shanghai Synchrotron Radiation Facility(SSRF)is a new beamline that provides X-ray micro-imaging capabilities across a wide range of time scales,spanning from 100 ps toμs and ms.This beamline has been specifically designed to facilitate the investigation of a wide range of rapid phenomena,such as the deformation and failure of materials subjected to intense dynamic loads.In addition,it enables the study of high-pressure and high-speed fuel spray processes in automotive engines.The light source of this beamline is a cryogenic permanent magnet undulator(CPMU)that is cooled by liquid nitrogen.This CPMU can generate X-ray photons within an energy range of 8.7-30 keV.The beamline offers two modes of operation:monochromatic beam mode with a liquid nitrogen-cooled double-crystal monochromator(DCM)and pink beam mode with the first crystal of the DCM out of the beam path.Four X-ray imaging methods were implemented in BL16U2:single-pulse ultrafast X-ray imaging,microsecond-resolved X-ray dynamic imaging,millisecond-resolved X-ray dynamic micro-CT,and high-resolution quantitative micro-CT.Furthermore,BL16U2 is equipped with various in situ impact loading systems,such as a split Hopkinson bar system,light gas gun,and fuel spray chamber.Following the completion of the final commissioning in 2021 and subsequent trial operations in 2022,the beamline has been officially available to users from 2023.

BACKGROUND RECTIFICATION AND FEATURE EXTRACTION OF IMAGE IN A SPOT WELD OF AL ALLOY X-RAY DETECTION

A primary study on Processing in X - ray inspection of spot weld for aluminum alloy spot welding,in- cluding for background simulation,acquisition of ideal binary image, and extraction and identifi- cation of defect features was presented.

Mini Review: Chemical Mesoscopics Notions in the Explanation of Polymeric Materials Modification Mechanism with Participation of Metal Carbon Mesocomposites

The paper is dedicated to the consideration of the chemical mesoscopics notions application for the explanation of polymeric materials modification mechanism by the metal carbon mesoscopic composites.The main peculiarities of these nanosized particles are following:a)the presence of unpaired electrons on the carbon cover;b)the structure of carbon cover consists from poly acetylene and carbine fragments;c)the atomic magnetic moment of inner metal is equaled to more than 1,3μB.The metal carbon mesocomposites activity depends on the medium and conditions influence because of the possible changes of the phase coherency and quantization of negative charges.

X-ray photon-counting detector based on a micro-channel plate for pulsar navigation

The pulse time of arrival （TOA） is a determining parameter for accurate timing and positioning in X-ray pulsar navigation. The pulse TOA can be calculated by comparing the measured arrival time with the predicted arrival time of the X-ray pulse for pulsar. In this study, in order to research the measurement of pulse arrival time, an experimental system is set up. The experimental system comprises a simulator of the X-ray pulsar, an X-ray detector, a time-measurement system, and a data-processing system. An X-ray detector base is proposed on the basis of the micro-channel plate （MCP）, which is sensitive to soft X-ray in the 1–10 keV band. The MCP-based detector, the structure and principle of the experimental system, and results of the pulse profile are described in detail. In addition, a discussion of the effects of different X-ray pulse periods and the quantum efficiency of the detector on pulse-profile signal-to-noise ratio （SNR） is presented. Experimental results reveal that the SNR of the measured pulse profile becomes enhanced as the quantum efficiency of the detector increases. The SNR of the pulse profile is higher when the period of the pulse is smaller at the same integral.

Influence of annealing temperature on the performance of Ge film and photon-counting imaging system

Compared with the traditional image intensifier with phosphor screen readout,the photon-counting imaging detector with charge induction readout is more beneficial in several aspects（e.g.,good imaging properties and time resolution） to astronomy,reconnaissance,bioluminescence,and materials research.However, the annealing temperature during the tube-making process can affect the properties of the Ge film,and consequently impair the performance of the detector.Therefore,the influence of annealing temperature on Ge film and on the detector is studied in order to determine the crucial parameters.The Ge films are prepared on ceramic and quartz glass by the use of an electron gun.They are analyzed by scanning electron microscope（SEM）,high-resistance meter,and X-ray diffraction（XRD）.The results show that the optimum substrate and annealing temperature are ceramic plate and 250℃,respectively.

Temporal Trends in Radiation Dose Associated with Coronary Computed Tomography Angiography

Background: In 2010, the International Atomic Energy Agency launched the “3A’s campaign” as an effective tool for primary cancer prevention. In 2011, the American Association of Physicists in Medicine recommended the size specific dose estimate (SSDE). Objectives: To audit doses of Coronary CT Angiography (Coronary CTA) in tertiary care referral center. Methods: We reviewed 998 consecutive Coronary CTA (from 2007 to 2012). Doses (CTDIvol mGy), DLP (mGy*cm), effective dose (DLP*0.014, mSv) were on-line archived. SSDE was estimated retrospectively. Appropriateness score was evaluated for exams performed from the 2010. Results: Overall median dose per Coronary CTA was 49.7 mGy for CTDIvol, 55.5 mGy for SSDE, 994.96 mGy*cm for DLP, 13.9 mSv for effective dose. Median DLP decreased over time (1452.94 in 2007, 1605.56 in 2008, 1113.49 in 2009, 759.99 in 2010, 448.61 in 2011 and 497.88 mGy*cm in 2012, p < 0.0001). SSDE was proportional to the size dependent factor (SDF);in patients with SDF > 1 (88%) CTDIvol underestimated SSDE (48.49 vs 57.19 mGy), whilst in patients with SDF < 1 (12%) CTDIvol overestimated SSDE (56.46 vs 50.3 mGy). Scans were appropriate in 58%, uncertain in 24%, and inappropriate in 18% of cases. Doses were similar in appropriate, uncertain or inappropriate examinations and in excellent-to-good (81%) vs. sufficient-to-poor (19%) image quality exams. Conclusions: Coronary CTA reference doses can be very misleading. SSDE can allow individual technique optimization. The dose is similar in appropriate and inappropriate examinations, and unrelated to image quality. The rate of inappropriate examinations is still too high even after dissemination of guidelines.

High efficiency positive and negative phase zone plates

We design a new kind of phase zone plates（PZPs） to improve the diffraction efficiency of soft x ray zone plates（ZPs）. The design replaces blank parts of PZPs with metals of negative phase shift at the working energy, which is called as the positive and negative PZPs（PNPZPs）. According to the calculation, PNPZPs have a higher maximum efficiency than conventional ZPs with the same zone width. With the help of a negative phase coefficient, it is much easier to achieve a π phase shift in one period, resulting in a smaller zone height. This design can help fabricate finer PZPs to achieve a better image resolution.

CT and MRI diagnosis of acute traumatic hepatic rupture:analysis of ten cases

In order to verify whether magnetic resonance imaging (MRI) is superior to computed tomography (CT) in the detection and characterization of intrahepatic hematoma in its acute stage, the MRI and CT features of acute traumatic hepatic rupture (ATHR) were retrospectively studied and compared. Methods: In the 10 cases of ATHR admitted to our institute, 3 were examined with CT, 1 with MRI and 6 with both CT and MRI in the first 24 hours post injury and 9 cases out of the 10 were checked up with MRI in the first week after injury of surgery. The shape of the traumatic lesions, the damages of the intrahepatic vessels and the severity of hepatic rupture displayed with CT and MRI were compared. Results: It was found that in the first 24 hours post injury, 66.6% of hepatic injuries were shown as hypointensity on T1 weighted images and low or high density on noncontrast CT. 100% of the lesions were identified as well marked hyperintensity on T2 weighted images. Damages of the hepatic and/or portal veins were observed in 7, 4 and 3 cases on T2 and T1 weighted images and noncontrast CT figures respectively. The severity of hepatic injuries were graded in 100%, 66.7% and 44.4%of cases with these 3 procedures respectively. Conclusions: On the basis of our findings, it is concluded that T2 weighted MRI is a more sensitive and reliable imaging modality in the detection and differentiation of the type and severity of acute hepatic rupture than T1 weighted imaging and noncontrast CT.