A Preliminary Ray Tracing Approach to Computational Electromagnetics for Reverberation Chambers

This paper summarizes a theoretical design analysis for the implementation of an electromagnetic modeling tool, focusing on the simulation of electromagnetic field propagation inside reverberation chambers. The simulation algorithms which have been developed rely on a ray tracing technique, adapted in such a way as to maximize compatibility with the specific requirements and parameters, as applicable for reverberation chambers. The most significant example of a typical parameter is the high rate of wave reflections inside the chambers’ cavity. An implementation of the algorithms was used for simulation of several theoretically predictable cases. Study of the results of these test cases showed that some of the design decisions and algorithms used need to be reviewed in order to optimize the computational aspects of the application, such as resource management (memory, CPU time). Results of typical sample cases are re- viewed in this paper as well, in order to identify possible pitfalls and objectives for future research.

SUMMARY OF CHINA-MADE X-RAY THICKNESS GAUGES FOR STEEL INDUSTRIES

There are two kinds of China- made X- ray thickness gaugemeters i.e. dual beam- dual detector system and single beam- single detector system- SM series, the latter is used dominantly in Chinese steel industries. The performance comparison between domestic and foreign instruments as well as its developments and applications is presented in this paper.

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.

The Different Patterns of Coronary Artery Calcification in Acute and Chronic Coronary Syndromes Determined by Electron Beam Computed Tomography

Objectives To compare the different patterns of coronary artery calcification (CAC) in acute and chronic coronary syndromes utilizing electron beam computed tomography. Background Pathologic, angiographic, and intracoronary ultrasound studies revealed sharp differences in the plaque morphology between patients with acute versus chronic coronary syndromes. Whether there are different patterns of coronary artery calcification in patients with stable angina pectoris (SAP) and in those with unstable angina pectoris (UAP) or acute myocardial infarction (AMI), however, remains unclear. Methods Two hundred and sixty - four patients, including 67 with SAP, 94 with UAP and 103 with AMI were studied with electron beam computed tomography for analysis of coronary artery calcification and with selective coronary angiography for determination of atherosclerotic lesions. CAC prevalence and calcium score were compared among three groups, and relation of CAC to the severity of atherosclerotic disease in the SAP and UAP patients was separately analyzed. Results Prevalence of CAC was 100 % in the SAP patients, significantly higher than the 87. 23 % in UAP patients and 86. 41 % among the patients with AMI ( P < 0. 05) . More patients and arteries in the SAP group had severe forms of calcium than those in the UAP and AMI group ( P < 0. 01), and the mean LN [CS + 1] (natural logarithm transformation of calcium score) of the SAP patients was much greater than that of the UAP and AMI patients (P < 0.001). The distribution of vessels with various CAC by luminal stenosis was different between SAP and UAP patients. The average CAC extent of the infarct - related arteries was less severe than that of the noninfarct - related arteries. Conclusions U-tilizing electron beam computed tomography, we demonstrated that there exist different patterns of coronary artery calcification in patients with acute versus chronic coronary syndromes, which may provide insight into the differences observed in the clinical and pathologic development between these two types of coronary artery disease.

Measurement and analysis of defects in high-performance concrete with three-dimensional micro-computer tomography

In order to investigate the effects of two mineral admixtures （i. e., fly ash and ground slag）on initial defects existing in concrete microstructures, a high-resolution X-ray micro-CT（ micro-focus computer tomography）is employed to quantitatively analyze the initial defects in four series of highperformance concrete （HPC）specimens with additions of different mineral admixtures. The nigh-resolution 3D images of microstructures and filtered defects are reconstructed by micro- CT software. The size distribution and volume fractions of initial defects are analyzed based on 3D and 2D micro-CT images. The analysis results are verified by experimental results of watersuction tests. The results show that the additions of mineral admixtures in concrete as cementitious materials greatly change the geometrical properties of the microstructures and the spatial features of defects by physical-chemistry actions of these mineral admixtures. This is the major cause of the differences between the mechanical behaviors of HPC with and without mineral admixtures when the water-to-binder ratio and the size distribution of aggregates are constant.

Clinical significance of mesenteric panniculitis-like abnormalities on abdominal computerized tomography in patients with malignant neoplasms

AIM To clarify the association of malignancy with mesenteric panniculitis-like changes on computed tomography(CT).METHODS All abdominal CT scans performed at North Shore University HealthS ystem showing mesenteric panniculitis from January 2005 to August 2010 were identified in the Radnet(Rad Net Corporation, Los Angeles, CA) database. Patients with a new or known diagnosis of a malignancy were included for this analysis. Longitudinal clinical histories were obtained from electronic medical records.RESULTS In total, 147794 abdominal CT scans were performed during the study period. Three hundred and fiftynine patients had mesenteric panniculitis(MP)-like abnormalities on their abdominal CT. Of these patients, 81 patients(22.6%) had a known history of cancer at the time of their CT scan. Nineteen(5.3%) had a new diagnosis of cancer in concurrence with their CT, but the majority of these(14/19, 74%) were undergoing CT as part of a malignancy evaluation. Lymphomas were the most common cancers associated with MPlike findings on CT(36 cases, 36%), with follicular lymphoma being the most frequent subtype(17/36). A variety of solid tumors, most commonly prostate(7) and renal cell cancers(6) also were seen. CT follow up was obtained in 56 patients. Findings in the mesentery were unchanged in 45(80%), worsened in 6(11%), and improved in 5 patients(9%). Positron emission tomography(PET) scans performed in 44 patients only showed a positive uptake in the mesenteric mass in 2 patients(5%). CONCLUSION A new diagnosis of cancer is uncommon in patients with CT findings suggestive of MP. MP-like mesenteric abnormalities on CT generally remain stable in patients with associated malignancies. PET scanning is not recommended in the evaluation of patients with mesenteric panniculitis-like findings on CT.

茎突舌骨韧带骨化致茎突综合征治愈分析

茎突综合征是1937年Eagle提出的因茎突过长和（或）方位、形态异常导致的周围血管、神经或其他组织受刺激引起的咽部不适，包括咽部异物感、咽痛、反射性耳痛及头颈痛等症状的一组综合征。临床上由于茎突过长或者方位异常引起的茎突综合征并不少见，但由于茎突舌骨韧带骨化致茎突综合征并不多见，现报道如下。

月经前期发作的鼻源性头痛

随着鼻窦CT诊断和鼻内镜诊疗技术的发展，大量鼻部疾病导致的头痛得以治愈。根据2004年国际头痛协会的分类，鼻源性头痛的第二种类型——黏膜接触点性头痛（mucosa contact point headache），因为缺少典型的鼻部症状，而分散就诊于其他学科，长期得不到合理诊疗。我们近期总结了多例临床上没有典型的鼻部症状，而是以各种类型的头痛为主诉就诊于神经内科等专科的患者，经过会诊筛查，确诊为鼻源性黏膜接触点性头痛，通过鼻内镜手术治愈。其中包括1组女性患者，长期被误认为是月经前期头痛，通过治疗证明是黏膜接触点性头痛的一种特殊存在形式，撰文总结如下。

食管黏膜下异物的CT诊断

总结1995-2004年10年间治疗的351例食管异物患者其中首次手术未发现异物12例，X线透视检查无阳性表现15例。此27例患者．经CT薄层扫描确诊，行食管镜检查取出并治愈，现报道如下。

Characterization of Ga NAs/ Ga As and Ga In NAs/ Ga As Quantum Wells Grown by Plasma-Assisted Molecular Beam Epitaxy: Effects of Ion Damage

The effects of ion damage on Ga NAs/Ga As and Ga In NAs/Ga As quantum wells ( QWs) grown by plas- ma- assisted molecular beam epitaxy have been investigated. Itis found thation damage is a key factor affecting the quality of Ga NAs and Ga In NAs QWs. Obvious appearance of pendello¨ sung fringes in X- ray diffraction pattern and remarkable im provement in the optical properties of the samples grown with ion removal magnets are observed.By removing nitrogen ions,the PL intensity of the Ga In NAs QW is improved so as to be comparable with that of Ga In As QW. The stronger is the magnetic field,the m ore obvious the PL intensity im provement would be.

A CT-based radiomics nomogram for prediction of human epidermal growth factor receptor 2 status in patients with gastric cancer

Objective: To develop and validate a computed tomography(CT)-based radiomics nomogram for predicting human epidermal growth factor receptor 2(HER2) status in patients with gastric cancer.Methods: This retrospective study included 134 patients with gastric cancer(HER2-negative: n=87;HER2-positive: n=47) from April 2013 to March 2018, who were then randomly divided into training(n=94) and validation(n=40) cohorts. Radiomics features were obtained from the CT images showing gastric cancer. Least absolute shrinkage and selection operator(LASSO) regression analysis was utilized for building the radiomics signature. A multivariable logistic regression method was applied to develop a prediction model incorporating the radiomics signature and independent clinicopathologic risk predictors, which were then visualized as a radiomics nomogram. The predictive performance of the nomogram was assessed in the training and validation cohorts.Results: The radiomics signature was significantly associated with HER2 status in both training(P<0.001) and validation(P=0.023) cohorts. The prediction model that incorporated the radiomics signature and carcinoembryonic antigen(CEA) level demonstrated good discriminative performance for HER2 status prediction,with an area under the curve(AUC) of 0.799 [95% confidence interval(95% CI): 0.704-0.894] in the training cohort and 0.771(95% CI: 0.607-0.934) in the validation cohort. The calibration curve of the radiomics nomogram also showed good calibration. Decision curve analysis showed that the radiomics nomogram was useful.Conclusions: We built and validated a radiomics nomogram with good performance for HER2 status prediction in gastric cancer. This radiomics nomogram could serve as a non-invasive tool to predict HER2 status and guide clinical treatment.

Findings of non-pathologic perfusion defects by CT arterial portography and non-pathologic enhancement of CT hepatic arteriography

AIM To recognize the characteristic findings of non pathologic perfusion defects with CT arterial portography (CTAP) and nonpathologic enhancement found in CT hepatic arteriography (CTHA). METHODS The manifestations of nonpathologic perfusion defects with CTAP and non pathologic enhancement found in CTHA were analyzed in 50 patients with primary hepatocellular carcinoma. RESULTS The false positive rate of perfusion defects detected in CTAP was 15 1%. The shapes of perfusion defects were peripheral wedge, small, round, and patchy. The occurrence rate of non pathologic enhancement found in CTHA was 22 0%. The shapes of non pathologic enhancement were small, round, irregular, and wedge. CONCLUSION There was a high frequency of non pathologic perfusion defects detected with CTAP and non pathologic enhancement found in CTHA. The simultaneous use of both procedures may help decrease the false positive rate, and increase the veracity of diagnosis for hepatocellular carcinoma.

Chemical and molecular characterization of Hong Dangshen,a unique medicinal material for diarrhea in Hong Kong

Aim To investigate the plant origin and the identity of the red substance on the surface of Hong Dangshen, a unique medicinal material for diarrhea in Hong Kong. Methods The HPLC fingerprints and 5S rRNA gene spacer sequences of Hong Dangshen were obtained and compared with those of genuine species of Radix Codonopsis. The X-ray diffraction spectrum of the red substance was analyzed and compared with that of Halloysitum fingerprints to the Codonopsis species and the highest similarity to Rubrum. Results Hong Dangshen showed very similar HPLC Codonopsis pilosula var. modesta in terms of 5S rRNA gene spacer sequences. The X-ray diffraction spectrum of the red substance was consistent with that of Halloysitum Rubrum. Conclusion The source plant of Hong Dangshen was suggested to be Codonopsis pilosula var. modesta, one of the genuine original plants of Radix Codonopsis （Dangshen） in the China Pharmacopoeia （2005 edition）. The red substance on the surface of Hong Dangshen was indicated to be Halloysitum Rubrum, a traditional medicinal mineral for chronic diarrhea. Our data suggest that Hong Dangshen is derived from the roots of Codonopsis pilosula var. modesta which has been processed with Halloysitum Rubrum, and the name is suggested to be Radix Codonopsis Praeparata Halloysita Rubra.

X-ray spectra induced in highly charged 40Ar^q+ interacting with Au surface

By use of optical spectrum technology, the spectra of X-ray induced by highly charged 40Arq+ ions interacting with Au surface have been studied. The results show that the argon Kα X-ray were emitted from the hollow atoms formed below the surface. There is a process of multi-electron exciting in neutralization of the Ar16+ion, with electronic con-figuration 1s2 in its ground state below the solid surface. The yield of the projectile Kα X-ray is related to its initial electronic configuration, and the yield of the target X-ray is related to the projectile kinetic energy.

Fast and accurate calculation of seismic wave travel time in 3D TTI media

The Tilted tilted transversely isotropic(TTI)media,a kind of anisotropic medium,widely exists within the earth.For faster calculation of travel times in the TTI anisotropic media,we modifi ed a minimum traveltime tree algorithm with high effi ciency by dynamical modifi cation of the secondary wave propagation region during the spread of seismic waves.To manage the wavefront points in the modified version,we used a novel minimum heap sorting technique to reduce the time spent on selecting secondary waves points.In this study,seismic group velocities were obtained from analytical solutions in terms of phase angle,and the corresponding phase angles were determined by binary search rather than approximate equations for weakly anisotropic media.For the most time-consuming part of the secondary wave traveltime calculation,the parallel computation was initially performed using multiple cores and threads.Numerical examples showed that the improved method can calculate seismic travel times and ray paths faster and accurately in a 3D TTI medium.For four cores and eight threads,the computing speed increased by six times when compared to the conventional method.

NON-DESTRUCTIVE MEASUREMENTS OF LEAD AND BARIUM IN ARCHAEOLOGICAL BONE SAMPLES USING XRF

The lead and barium contents in sixteen archaeological bone samples from 10 persons buried in Dalsby, Sweden, were determined by means of X- ray fluorescence analysis using two "Co sources for excitation and a planar Ge detector for registration of the X- rays. The lead concentrations were found to be less than 168μ g/g, and the barium concentrations were in the range of 15- 97μg/g.

CT-GUIDED PERCUTANEOUS TRANSTHORACIC FINENEEDLE ASPIRATION BIOPSY OF SMALL PERIPHERAL PULMONARY LESIONS

CT guided percutaneous transthoracic fine needle aspiration biopsy (PTFNAB) was performed in twenty four sputum negative cases of small peripheral pulmonary lesions smaller than 2 cm in diameter, which are not easily diagnosed or accessible to fibrobron choscopes. After thin slide scanning and localization with Somatom DR H computed tomography, pulmonary nodules were biopsied with a 20 Gauge needle guided by a ruler specially designed. Biopsy materials were used for cyto and histopathologic examinations. The diagnosis accuracy of biopsy was evaluated by the result of postoperative pathology and/or follow up for 2 years. Sixteen pulmonary lesions were proved to be malignant and 8 were benign. The sensitivity was 75.0% (12/16), speciti vity 100% (8/8) and accuracy 83.3% (20/24) according to cytopathology and 87.5% (14/16), 100% (8/8), 91.7% (22/24) by histopathology, respectively. Two cases of early stage peripheral lung cancer were detected and proved by operation. CT guided PTFNAB is safe and quick for diagnosis with high accuracy for small peripheral pulmonary lesions which are usually negative in sputum examination and bronchoscopy. PTFNAB should be routinely used in the diagnosis of lung neoplasms.

Study of (Ga, Mn)N prepared by Mn-ion implantation using optical techniques

This paper reports that （Ga, Mn）N is prepared using implantation of 3at.% Mn Ions into undoped GaN. Structural characterization of the crystals was performed using x-ray diffraetion（XRD）. Detailed XRD measurements have revealed the characteristic of Mn-ion implanted GaN with a small contribution of other compounds. With Raman spectroscopy measurements, the spectra corresponding to the intrinsic GaN layers demonstrate three Raman active excitations at 747, 733 and 566 cm-1 identified as EI（LO）, A1 （LO） and E~, respectively. The Mn-doped GaN layers exhibit additional excitations at 182, 288, 650 725, 363, 506cm^-1 and the vicinity of E~ mode. The modes observed at 182, 288, 650 725em 1 are assigned to macroscopic disorder or vacancy-related defects caused by Mn-ion implantation. Other new phonon modes are assigned to Mnx-Ny, Gax-Mny modes and the local vibrational mode of Mn atoms in the （Ga, Mn）N, which are in fair agreement with the standard theoretical results.

CT Manifestations of Lung Changes and Complications in Patients with Severe Acute Respiratory Syndrome

Objective:To investigate the rol e of CT scanning in diagnosing severe acute respiratory syndrome(SARS). Methods: One hundred and twelve times of spiral CT scanning, 106 t imes on the chest with standard pulmonary and mediastinal window, 5 on the brain and once on the abdomen, were performed in 82 patients (37 males and 45 females ) of SARS. Results: Bilateral shadows showed in 66 patients (80.48%) and unil ateral shadow in 16 (19.52%). The lung CT findings were sub pleural focal con solidation in 26 patients (31.70%), flaky cloudy opacity in 53 (64.63%), large a rea consolidation in 9 (10.97%), ground glass blurry shadow in 31 (37.80%), a lveolar substantive shadow in 14 (17.07%) and interstitial changes in 16 (19.51% ). The pulmonary CT signs of SARS were relatively characterized by: (1) The lesi ons tending to multiply occur, mostly to be bilaterally distributed and commonly involved in the lower lung field. (2) The lung shadows mostly showed as sub pleural focal consolidation, flaky cloudy shadow, large area consolidation, grou nd glass blurry shadow, and often accompanied with signs of broncho inflat ion. (3) Having opacified nodular shadows in the alveolar cavities. (4) Rapid pr ogressions or changes on the size, amount, and distribution of the lesions likel y to be found in dynamic observation of chest X ray and CT scanning, i.e., ma rkedly dynamic changes found within 24 to 48 hrs. Lesions with these characteris tics may be recognized as pulmonary changes possibly induced by SARS. Complicati ons were found in 6 patients (7.31%), including tuberculosis of lung and brain a ccompanied with pneumomediastinum in one patient, secondary infection of lung in 2, pneumothorax in 1, pulmonary fungus in 1, and pyothorax in 1.Conclusion: CT scanning is a sensitive method for diagnosis of SAR S, by which more accurate assessment of the abnormal changes of lung and occurre nce of complications in SARS patients can be made.

A comparative study on CT imaging and pathologic presentation of the periphery of hepatocellular carcinoma using in vivo specimens of liver transplantation

Objective:To examine CT and pathologic presentations of the periphery of hepatocelllar carcinoma (HCC) by using in vivo liver specimens from orthotopic liver transplantation (OLT) and to see whether there is any correlation between them. Materials and Methods:Forty-two patients with HCC confirmed by pathology and liver transplantation were included. Plain CT scan covering the whole liver was done, followed by arterial and portal venous phase scanning. The delay time was 25 s and 60 s after injection of contrast medium. Fresh liver samples were evaluated, sliced and stained with HE and the standard immunoperoxidase method using facterⅧrelated antigen (F8RA) monoclonal antibody to study CT presentation of the periphery of tumor and compare them with pathologic findings. Results: (1) Tumors with clear boundaries on CT scan reflected the presence of tumor capsules in pathologic sections. Most tumors with unclear boundaries had no capsules and grew in an invasive pattern; (2) Tumors with unclear boundaries or high density on dynamic enhancement usually had abundant newborn vessels in the periphery and were poorly differentiated, while those with low density had few newborn vessels and were well differentiated; (3) When microvessel density (MVD) was>30, the occurrence of intrahepatic daughter foci was higher. Conclusion: (1) CT morphologic classification of the HCC periphery can well reflect the intactness of tumor capsules, which is helpful for preoperative assessment of tumor infiltration and cancer cell grading; (2) CT enhancement presentation of the HCC periphery in arterial and portal phases may reflect pathologic changes and help predict the prognosis at large.