使用散射X射线的理论强度进行土壤、岩石中的微量重元素的X射线荧光分析

是依据FP法进行土壤、岩石中的Pb ,As等微量重元素的X射线荧光定量分析的方法。FP法对定量元素的荧光X射线进行理论强度计算 ,同时对散射X射线也进行计算 ,用于多种样品的定量分析 ,提高了定量元素准确度。     

X射线荧光分析法测定铁矿石中全铁

铁矿石中全铁的含量范围通常较宽,因此需要高的分析精确度。尽管熔融制样法已经被普遍用于铁矿石的X射线荧光光谱分析,但作为样品制备的另一种方法,压片法由于简便、快捷的特点,其应用需求同样较大。康普顿散射比法已经被普遍用于岩石等样品中的重金属元素测定,其中荧光X射线与X射线管线发射的康普顿散射X射线的强度比被用作校正。不过,这种方法不能为矿石和精矿中高含量重金属元素的测定提供足够的准确度。本研究建立了一种新的方法,在元素间校正项中,将基本参数法获取的理论α系数用于康普顿散射比校正。本方法可以将铁矿石中全铁含量的测定准确度提高到0.14%（质量分数）。     

X射线荧光光谱法测定生石灰中钙、镁、硅、硫

介绍了用X射线荧光光谱仪测定生石灰中Ca ,Mg ,Si和S含量的方法。通过条件试验 ,确定了各元素的最佳测定条件 ,同时探讨了研磨样品时间对X射线荧光强度和分析曲线的影响、放置时间对样品含量的影响。实践证明 ,该方法快捷、简便、准确。RSD在 0 . 0 17%～ 0 .93 %之间     

X射线荧光光谱分析技术在质量检测中的应用探讨

简要介绍了X射线荧光光谱分析技术原理、光谱仪类型及分析方法,阐述了X射线荧光光谱分析技术在质量检测中的应用,对X射线荧光光谱检测应用中仪器选型配置、样品制备方法选择、定量分析技术进行了探讨.     

X射线荧光光谱分析硫化铜矿及其精矿的进展

硫化铜矿及其精矿含有较高的硫和铜。不同价态的硫所发射的X射线谱(K_α、K_β)发生位移,K_α/K_β谱线强度比值不一致;硫腐蚀铂金坩埚,铜能与铂金生成合金,给X射线荧光光谱(XRF)分析造成困难。对国内发表的X射线荧光光谱分析硫化铜矿及其精矿的文献进行了综述。总结了粉末压片法和熔融制样法制备试料片的条件、标准试料的选择和X射线荧光光谱仪分析条件,以及在铜矿物类质同象物相鉴定、铜精矿样品氧化条件及其机理研究等方面的应用情况,并展望了XRF在硫化铜矿及其精矿成分分析中的应用前景。     

利用二级筛分控制烧结矿粒度效应对X-荧光压片分析法的影响

通过X射线荧光光谱粉末压片法分析烧结矿中的TFe．SiO2、Ca0、MgO、Al2O3等成分的含量，在制样过程中采用标准化研磨方法和二级筛分控制样品的粒度，在光谱仪上测量样品的X射线荧光强度。通过软件计算出样品的化学成分含量。实验结果表明，采用该方法测定的数据结果稳定，精确度高，可满足生产工艺的要求。     

X射线荧光光谱分析稀土的研究进展（综述）

本文对近二十年来X射线荧光光谱仪在稀土分析方面的应用进行了综述。总结了环境、矿物、稀土富集物、单一稀土化合物、稀土金属、合金、稀土功能材料以及过程分析中稀土元素的X射线荧光光谱分析方法,检测方法涉及钢铁、有色金属、石油化工、地质、生物、电子材料等领域。展望了X射线荧光分析方法在稀土行业的应用前景。     

浅析在矿勘查中便携式X射线荧光分析仪的应用方法

在地质勘查仪器设备中的X-荧光分析仪,尤其是便携式 X 射线荧光分析仪在矿物质样品检测中,矿物质样品通过X 射线中的照射的作用下散射出来的 X 射线,能够快速、高效率、批量地完成分析出各种金属元素成分,便携式 X 射线荧光分析仪在我国繁重的地质矿物质分析中起到了积极的作用。本文主要对便携式 X 射线荧光分析仪的工作原理及应用进行展开分析,并列举了便携式 X 射线荧光分析仪在矿石勘查中的应用,望本论文为地质勘查工作者提供参考。     

X射线荧光分析原料中钾钠铅锌的方法和研究

为了快速有效地测量出K、Na、Pb、Zn等有害元素在烧结矿、精矿粉等物料中的含量,利用化验室现有的X射线荧光仪,通过购买标样进行熔样分析,并绘制了分析曲线。采用对比检验方法对X射线荧光分析数据进行了检验,结果表明化学分析与X射线荧光分析无明显差异,荧光分析准确度、精密度能够满足生产要求。     

热镀锌合金化层铁含量对X射线荧光光谱法 测定镀层质量影响的探讨

采用X射线荧光光谱法(XRF)测定热镀锌合金化镀层时,由于ZnKβ或FeKα特征谱线强度随着合金化层中Fe含量的变化而变化,导致镀层分析结果产生偏差。实验分别用X射线荧光光谱法和重量法进行合金化热镀锌样板的镀层质量检测,验证不同Fe含量变化对X射线荧光光谱法分析镀层质量的影响程度;建立了两种检验方法的差值与Fe含量的回归关系,利用w=(w_Fe-10.81)/0.9960+w＇(其中w为校正后镀层质量;w_Fe为铁含量,%;w＇为校正前X射线荧光光谱法测定的镀层质量)对X射线荧光光谱法测量镀层质量偏差的校正。研究表明:Fe质量分数控制在8%~12%范围内,采用X射线荧光光谱法测量合金化镀层质量能满足精度控制要求,可以接受;w(Fe)＜8%或w(Fe)＞12%时,利用回归方程式理论校正由于Fe含量变化引起的X射线荧光光谱法测量合金化镀层的偏差,提高了分析准确度。对不同Fe含量合金化热镀锌钢板镀层质量的验证结果表明,校正后镀层质量的测定值与重量法测定值一致。     

Mutation induction by heavy ion beams and X-rays: analysis with cultured cell line

This study was performed to determine the biological effects of heavy ion beams on cultured cells. V79 cells were irradiated with carbon or neon beams or X-rays, and cell survivals was calculated by the colony assay method. The Do values for 150 kVp X-rays, 20 keV/micron and 80 keV/micron carbon beams, and 80 keV/micron neon beams were 2.2Gy, 1.8Gy, 1.0Gy and 1.4Gy, respectively. After 7-10 day expression periods, the mutation frequencies at the hypoxanthine-guanine phosphribosyl transferase (hprt) locus were analyzed from the numbers of colonies formed in media supplemented with 6-thioguanine. An extremely higher frequency of mutation was observed with heavy ion beams compared with X-rays. Both cell killing effect and the mutation induction were enhanced when the LET of carbon beams was increased from 20 to 80 keV/micron. These results mean that carbon beams had a stronger cell-killing effect than X-rays, but also carried a high risk of mutation induction. On the other hand, neon beams yielded cell survival curves similar to those of carbon beams, but they had a smaller mutation induction effect than carbon beams. The effect of fractionated irradiation (3 hr interval) on cell survival and mutation frequency were also examined. When cells were irradiated with X-rays, cell survival was increased by fractionation, but the mutation frequency was not modified. Irradiating cells with fractionated carbon beams, survival curves were not affected, but mutation frequency was reduced.     

The state of residual stress in the near surface region of homogeneous and heterogeneous materials after grinding

The residual stresses near the surface were measured after grinding under different conditions with X-rays of various wavelengths using various peaks from homogeneous and heterogeneous materials with fcc-and bcc-structures. The strain distributions were subject toψ-splitting. A method was elaborated to measure the variation of stress as a function of depth with X-rays of various wavelengths. For two ground steels it was shown that this method gave stress distributions with depth which were in good agreement with those evaluated from stress measurements with one wavelength and layer removal. Normal-and shear stresses decreased absolutely with increasing depth. The existence of shear residual stresses was discussed and it was concluded that for heterogeneous materials these stresses can be compensated by those of opposing sign in the other phases.     

Evaluation of routine postoperative chest X-rays in the management of the cardiac surgical patient

OBJECTIVES: To evaluate the role of routine chest X-rays in the management of patients post cardiac surgery. METHODS: 340 adult patients undergoing cardiac surgery were studied in three consecutive groups (A, B, C) of 100 patients each. Forty patients were excluded due to the intensive care stay greater than 36 h (n = 35), or early mortality within 36 h (n = 5). Routine chest X-rays were performed according to different protocols in Groups A and B. In group C there were no routine chest X-rays during the entire postoperative period [corrected]. In all three groups chest X-rays were performed where clinically indicated. Group A had three routine chest X-rays post-operation. Group B had one routine chest X-ray on day 4 post-operation. Group C had chest X-rays only when indicated. The X-rays were evaluated in terms of their assistance value and the resultant number of interventions. RESULTS: The three groups were similar preoperatively for age, sex, preoperative left ventricular function, presence of chronic obstructive airway disease and type of operation performed. The total number of chest X-rays in groups A, B and C were 304, 133 and 36, respectively. The number of chest X-rays leading to interventions were five, four and four in groups A, B and C, respectively. Chest X-rays that helped in management were 36, 28, and 28, respectively, in the same groups. There was no mortality or morbidity attributable to non-performance of routine chest X-ray. CONCLUSIONS: Routine chest X-rays post-cardiac surgery are of very little value and patients are adequately managed by performing chest X-rays only when clinically indicated. There was no increased mortality or morbidity attributed to lack of routine chest X-rays in any of these groups. We recommend performing chest X-rays only when clinically indicated in satisfactorily recovering adult cardiac surgical patients.     

0.3 keV carbon K ultrasoft X-rays are four times more effective than gamma-rays when inducing oncogenic cell transformation at low doses

Oncogenic transformation and inactivation were investigated in C3H10T1/2 mouse embryo fibroblasts exposed to proton-induced 0.28 keV carbon K (CK)-characteristic X-rays and 60Co gamma-rays as reference radiation at high dose-rate (2-3 and 0.7 Gy/min respectively). Both oncogenic cell transformation and cell inactivation followed a linear-quadratic relationship with dose. At low doses where the linear component dominates CK ultrasoft X-rays were more effective, by a factor of 4, at inducing oncogenic cell transformation and cell inactivation compared with 60Co gamma-rays. For both endpoints the RBE of CK ultrasoft X-rays gradually decreased with increasing dose mainly due to the greater quadratic component for 60Co gamma-rays compared with CK ultrasoft X-rays. Our experimental data are in agreement with the hypothesis that single DNA double-strand breaks (dsbs), which are induced by 0.28-keV ultrasoft CK X-rays, may lead to oncogenic cell transformation. With increasing absorbed dose, i.e. with decreasing mean distance between dsbs induced by 0.28-keV ultrasoft X-rays, oncogenic cell transformation and cell inactivation may also be induced by interaction between those dsbs.     

The monitor findings of digitalized conventional wrist x-rays

The study aimed at proving the reliability of monitor systems with the matrix of 1024 x 768 for the detection of scaphoid fractures compared to conventional X-ray. Moreover, we were interested in the significance of procedures of digital imaging post processing, depending in particular on the experience of investigators. 5 investigators with different levels of experience analysed 57 X-rays of the wrist. They compared conventional X-rays with images on a high screen monitor system after the digitalisation of these X-rays by a CCD-scanner and analysed untreated and treated images. A 5-point scale ROC analysis was used for evaluation. The analysis covered a total of 1740 evaluations. The untreated images seen on the monitor system proved slightly better than conventional X-rays. Post-processing has no evident advantage over untreated images. Differing levels of experience had no effect whatsoever on the identification of findings.     

Towards a partnership in care: nurses' and doctors' interpretation of extremity trauma radiology

Receiver operating characteristic (ROC) is a method of assessing the sensitivity and specificity of a classification at a variety of thresholds. It allows a quantitative comparison of several classifiers. It was used in this study to compare doctors and nurses with respect to their ability to diagnose X-rays. X-ray interpretations were measured using a confidence rating scale, on 50 radiographs from a generated library of extremity X-rays following trauma. The catalogue of radiographs were selected from real cases of extremity trauma which were considered representative of typical accident and emergency case scenarios. The interpretations of doctors and nurse practitioners were compared with the gold standard of the consultant radiologist. No significant differences were seen between the two groups. This study is based on work done for a master's thesis by one of the authors (Overton) supervised by the other author.     

The early evaluation of induced osteoarthritis in rats with 99Tcm-pertechnetate scans

Osteoarthritis was induced in 30 adult rats by serial injection of papain (3.5 mg kg-1) into the right knee on days 1, 4 and 7 of the study, with equal volumes of normal saline being injected into the left knee as a control. The severity of the induced arthritis was observed after the subcutaneous injection of 37 MBq kg-1 (1 mCi kg-1) 99Tcm-pertechnetate in the neck 24 h and 1, 2, 4, 6 and 8 weeks after the first intra-articular injection of papain. The ratio of radioactivity in the right compared with the left knee of each rat was measured as an index of the severity of osteoarthritis. After the scans, X-rays of both knees were obtained. At each state of progression, a rat was sacrificed and bilateral knee sections were performed for further pathological evaluation. The results were then compared with the changes in the radioactivity ratio and the X-rays. The radioactivity ratio of the knees reached a peak approximately 25 min after the subcutaneous injection of 99Tcm-pertechnetate and this value was chosen as the index of the severity of osteoarthritis. Marked differences in radioactivity in the left and right knees were observed as early as 24 h after the first intra-articular injection of papain. The radioactivity ratio increased with time, which correlated well with pathological changes. Joint space narrowing was not found on X-ray until 4 weeks post-injection. The results showed that the 99Tcm-pertechnetate scans correlated well with the pathological changes and that this method can detect osteoarthritis earlier than joint X-rays. It is suggested that a 99Tcm-pertechnetate scan is a useful means of evaluating early changes in induced osteoarthritis in rats.     

Blastocyst attachment and early invasion during oestradiol-induced implantation in the mouse

Twelve patients with retroperitoneal tumors were examined sonographically and roentgenologically before and after radiation therapy. The sonograms were evaluated quantitatively by planimetry. Nine cases revealed analogous results in roentgenologic and in sonographic examinations. In three cases sonography revealed a tumor regression which was not verifiable with X-rays. In consideration of these results, sonography is used by us as a primary method for examination of retroperitoneal tumors during the follow-up control.     

An audit of radiotherapy patient doses measured with in vivo semiconductor detectors

Uncertainties exist both in the basic data from which a radiotherapy plan is produced and in the process whereby such a plan is translated into the patient set-up during treatment. Individual parts of the radiotherapy process are subject to checks, but the overall accuracy of treatment delivery is not routinely evaluated. In vivo dosimetry by means of a semiconductor detector system can be used to measure the cumulative error in the radiotherapy treatment dose delivered. A direct patient dosimetry system was commissioned and introduced in January 1993 for the routine evaluation of the doses patients receive. Since its introduction a total of 1000 patients have been monitored for a range of radiotherapy applications, comprising 300 breast treatments (6 MV X-rays), 150 head and neck treatments (6 MV X-rays) and 550 pelvis. abdomen and thorax treatments (10 MV X-rays). The results of this audit show that less than 5% of all patients monitored gave a systematic error more than +/- 5% for a single field, or more than +/- 2.5% for the "estimated overall error" in the isocentre dose. The causes of these errors were identified and appropriate action taken where necessary. It is suggested that this method could be used routinely in radiotherapy treatment to assess the overall performance of the treatment process.