工频X线机和中频X线机在胸部计算机X线摄影中应用分析

目的分析工频X线机和中频X线机在胸部计算机X线摄影(CR)中的图像质量,监测相应辐射剂量,比较两种X线机在CR摄影中的适用性。方法使用工频X线机和中频X线机摄取2～3岁小儿胸片共28例,分析图像质量,监测辐射剂量;并对两种X线机高压输出及IP对X线吸收特点进行分析。结果同工频X线机相比,中频X线机更易获得优质图像,且降低了辐射剂量。结论在CR应用中,中频X线机比工频X线机有明显优势。     

5—3 医用X线电视系统概论

医用X线电视系统不仅提高放射诊断的质量和效率,还显著降低辐射剂量,现我国正大力推广和普及。作为近代遥控X线机、数字减影、人工设色、CT(计算机多轨多断层)等先进设备必不可少的配套组件,现医用X线电视系统正迅速发展,为近代医疗快速、准确诊断提供最新、最可靠的依据。本文论述了: 一、医用X线电视系统,显著突出的优点和医学科研、教学及临床中的应用。二、医用X线的研制、应用和世界最新发展的趋势(PET系统)。     

数字化乳腺成像系统量子探测效率检测方法研究

数字化乳腺X线摄影技术已成为临床检测早期无症状隐匿性乳腺癌的重要手段,在此背景下,评价数字乳腺机性能的量子探测效率(DQE)检测方法,是国内外临床医学界和医学影像检测部门所关注的重要课题。针对相对成熟的IEC62220-1标准不适用于辐射剂量小、辐射野小的数字乳腺机DQE检测的问题,本文较深入地研究了基于IEC62220-1-2标准的数字乳腺机DQE检测方法和具体数字图像处理算法的实现。并将该DQE检测手段实施于辽宁省医疗器械检验所受检产品某公司生产的乳腺机,得到了相应的DQE测试结果,最后,本文讨论了数字化乳腺成像系统量子探测效率的重要影响因素。     

医用诊断X射线源的研究进展

通过研究医用诊断X线机射线源、CT设备X射线源、特殊X射线源等比较X射线产生的物理原理和应用,探索基于韧致辐射的X射线源技术的局限性,提出X线机球管的未来发展方向。X射线的最大应用领域是在医学诊断中基于医学图像引导的诊断和治疗。通过研究其他等效X射线源如液态金属喷射轫致辐射源等,拓宽了X射线的应用领域。展望了X射线球管的关键特性和材料在医学诊断技术发展的前景。     

放射吸收法（RA）在骨质疏松诊断中的应用

目的:探讨放射吸收法(RA)在骨质疏松诊断中的作用.方法:从骨质疏松定义开始,相继介绍骨质疏松诊断标准和现行测量方法,可选择的测量部位,放射吸收法的分类及相关原理,以及精确度和准确度.结果:放射吸收法被证明其与DXA具有很高的相关性,RA技术在X线机基础上进行,无须添加新设备;检查费用也比较低;仅需一次曝光,所接受的射线量也较低.结论:RA技术是目前BMD测量中最为准确、方便、快捷的方法之一.其投入少、费用低的特性更适合我国的基本国情,在我国目前及未来具有广阔的前景,值得普遍推广.     

经皮椎体强化治疗过程中的辐射量与防护

背景：大量研究表明在经皮椎体强化治疗中的穿刺与骨水泥注射阶段,术者所受辐射量较高。 目的：综述经皮椎体强化术中辐射量与防护措施的进展。 方法：分别以“经皮椎体强化,辐射剂量,放射防护;percutaneous vertebral augmentation,radiation doses,radiation protective”为检索词,应用计算机检索万方数据库及PubMed数据库1995年1月至2014年12月有关文章,纳入经皮椎体强化放射防护的文献。 结果与结论：距离防护是基本的防护措施,术者应在不影响操作的情况下,尽量增加与放射线距离。此外术中C臂机的最优设置和最佳摆放、穿保护装置、放屏蔽设施、术中导航及对术者进行辐射方面培训等均可明显减少辐射量;改进骨水泥注射装置,包括遥控骨水泥注射技术,使其更方便操作且不增加患者辐射量;此外手术床对放射量的影响还有待进一步研究。相信随着对放射防护研究的不断深入,椎体强化将会更安全地应用于临床。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

冯晓源教授连任国际放射学会执行委员会委员

第27届国际放射学大会(International Congress of Radiology)2012年5月初在巴西圣保罗市举行。会议期间,国际放射学会选举了新一届的执行委员会(Executive Committee of International Society of Radiology)中华放射学主任委员、上海市生物医学工程学会副理事长、复旦大学医学院附属华山医院放射科主任冯晓源教授再次当选为执委会委员。     

4—4 放射治疗食管癌非模拟机定位方法探讨

虽说摸拟定位机已进入临床应用。但在国内尚未普及,我们利用直角三角形的几何原理,借助普通X线诊断机在一张X光片上拍摄双重食管影像的方法,解决了食管癌交角布野定位的问题,临床应用1200例,效果满意,方法如下: 1.首先在透视下直接标出胸前后背部垂直野的纵横中心交点(这里的背部野仅作计算交叉野旁开距和布交叉野时参考用)。 2.置患者于摄影床上,a平躺仰卧、紧贴背部放一装有X光胶片的暗盒。然后(以     

获得性免疫缺陷综合征（艾滋病）肺部X线与病理

分析了2例艾滋病肺部病理及X线特征,以提高艾滋病肺部病变X线诊断水平。1例合并混合性细菌性感染;1例合并卡氏肺囊虫肺炎及Kaposi's肉瘤。X线胸片:两肺野弥漫性网结节状病变特征。     

干水组织等效材料的辐射特性和热力学特性研究

从1895年伦琴发现X射线以来,X线射被最先应用于医学领域,许多医学家和实验物理学家不断努力,试图利用所谓组织等效材料(tissue eguivalent matevials)来复制射线在体内外的相似效应。1906年奥地利放射学家Kienboch最早提出一定厚度的铝箔与肌肉组织辐射效应相似的观点。随着科学技术的发展和核技术在工农医领域广泛的应用,到八十年代初辐射等效材料已形成五大系列(固体、水、液体、凝胶、粉剂)160余种,而液体和凝胶材料占30％,展现了人体组织替代物和仿真人体模型诱人的发展前景。新近国际辐射剂量单位和测量委员会(ICRU)组织替代物和体模专门委员会主席D、R、White指出“随着现代医疗照射设备和技术的进步,将需要更多的仿真体模和组织替代物材料,放射物理工作者应把研究和制备这些体模和材料视为自己的光荣职责”。     

三维分析仪与两维矩阵射野测量的比较

目的:应用不同仪器与方法测量加速器6 MV X线射野的特性,比较各方法的优劣和局限性,探讨快速简便检测射野特性的方法。材料与方法:分别采用电离室和半导体探头配合三维射野分析仪测量加速器6 MV X线不同射野大小的百分深度剂量曲线PDD和离轴比曲线OCR,并以二维电离室矩阵测量相同条件的OCR。(1)比较采用电离室和半导体探头测量PDD的差别。(2)比较两维矩阵与电离室半导体探头测量射野的对称性、平坦度、射野大小和半影等的差别。结果:对小于15 cm×15 cm照射野,半导体探头和电离室测量PDD的结果一致性较好,两者偏差小于1.3%。对于20 cm×20 cm照射野,半导体探头的测量结果大于电离室,最大差别3.5%,偏差为2.6%。用半导体探头与电离室测量射野的大小,两者的最大差别为0.6 mm,两者有较好的一致性,二维电离室矩阵测量与前两者比较,最大差别为2.9 mm,最小差别0.5 mm。三种方法测量的射野平坦度差别在1.2%~2.6%,矩阵的测量数值在半导体和电离室测量范围之内。结论:在检测加速器射野性能时,二维矩阵可以快速检测射野平坦度、对称性,但测量射野大小时可能有较大误差,不宜用作验收加速器和收集...     

New Approaches to Development of High-Performance X-Ray Sources Based on Nanomaterials

The research and patent literature as well as experimental results obtained in our laboratory are discussed. Monocrystal and nanotechnological materials provide progress in X-ray radiation sources. Effective medical X-ray radiation sources use autoemission cathodes and thermoemission cathodes made of carbon nanotubes and tungsten nanocomposites. Nanocomposite cathodes and anodes increase the service life of X-ray radiation sources.     

Synchrotron radiation techniques for structural characterisation of biological entities: an example with renal stone analysis

This paper describes the opportunities given by the synchrotron radiation techniques regarding the structural characterisation of biological entities. After a short recall on the characteristics of the synchrotron radiation, are described the experimental devices based on fluorescence X, wide angle X-ray scattering and X-ray absorption spectroscopy, which may applied for biological samples, especially in the field of stone analysis. Recent progresses in medical research using synchrotron radiation will be also discussed.     

Development and operation of a pixel segmented liquid-filled linear array for radiotherapy quality assurance

A liquid isooctane (C(8)H(18)) filled ionization linear array for radiotherapy quality assurance has been designed, built and tested. The detector consists of 128 pixels, each of them with an area of 1.7 mm x 1.7 mm and a gap of 0.5 mm. The small pixel size makes the detector ideal for high gradient beam profiles such as those present in intensity modulated radiation therapy (IMRT) and radiosurgery. As the read-out electronics we use the X-ray Data Acquisition System with the Xchip developed by the CCLRC. Studies concerning the collection efficiency dependence on the polarization voltage and on the dose rate have been made in order to optimize the device operation. In the first tests, we have studied dose rate and energy dependences. Dose rate dependence was found to be lower than 2.1% up to 5 Gy min(-1), and energy dependence lower than 2.5% up to 20 cm depth in solid water. Output factors and penumbras for several rectangular fields have been measured with the linear array and were compared with the results obtained with a 0.125 cm(3) air ionization chamber and radiographic film, respectively. Finally, we have acquired profiles for an IMRT field and for a virtual wedge. These profiles have also been compared with radiographic film measurements. All the comparisons show a good correspondence. The device has proved its capability to verify on-line therapy beams with good spatial resolution and signal-to-noise ratio.     

X射线诊断所致受检者辐射剂量的表征与评估研究进展

目的：为正确评价医用X射线诊断所致受检者的辐射剂量，探讨科学且实用的测量、估算与评价各类诊断所致受检者剂量的相应方法。方法：从便于电离辐射剂量学分析角度出发。将各种医用X射线诊断分类为普通X射线检查、数字X射线摄影、乳腺X射线摄影和X射线计算机断层扫描。对比分析各类X射线诊断所致受检者剂量的各种表征量及其相应的直接测量或利用相应模式来推算的方法。结果：各类医用X射线诊断所致受检者剂量的表征量目前大都可以通过直接测量来得到，但即便辅助以各种模体，也只能准确测量出特定条件下的表征量，另外直接测量工作费时且费用高；利用有关参数建立的数理模式不仅可较方便推算各种诊断类型的辐射表征量，同时它们还可用于估算与辐射风险直接相关的受检者的有效剂量；后者更适于用来开展大规模调查和评价群体剂量及其相应的辐射风险。结论：准确评价X射线诊断所致受检者辐射剂量是医学物理领域颇为重要的课题，研究建立科学合理的辐射剂量评价模式具有重要的实用价值。     

Radiographic staging procedures and radiotherapy of malignant lymphoma

Radiographic studies play an important role in the clinical staging of malignant lymphoma (ML). Conventional procedures are plain chest X-ray, lymphangiography, gastrointestinal series, and 67Ga scintigraphy. Gastro-intestinal series is essential in non-Hodgkin's lymphoma (NHL) of Waldeyer's ring and thyroid. 67Ga scintigraphy is a non-invasive procedure useful in the screening of ML. Recently marked improvements have been made in the diagnostic modalities. CT scan and NMR have made it very easy to diagnose ML of the central nervous system and detect the extension of tumors at all sites. In some cases with Hodgkin's disease (HD), staging laparotomy is necessary, but not in cases with NHL. If tumors are localized, subtotal or total nodal irradiation is performed for patients with HD, and generous involved field is employed for NHL with or without combined chemotherapy at our department. Good local control is obtained except for NHL of the central nervous system at a total dose of 40-50 Gy. NHL is prone to relapse outside the radiation field. Therefore we consider that combined chemotherapy is indicated for NHL such as T-cell lymphomas, those with high grade histology classified according to the Working Formulation, and with involvement of lymph nodes larger than 6 cm in diameter.     

Influence of field size on a PTW type 23342 plane-parallel ionization chamber's response

The response of a PTW type 23342 plane-parallel ionization chamber, both in air and in phantom, was evaluated for x-ray tube potentials between 30 and 100 kV and radiation field diameters ranging from 30 to 70 mm. The experiments were performed with a calibrated Pantak x-ray machine and made use of the same set of x-ray qualities adopted by the PTB primary laboratory for the calibration of such chambers. A Plexiglas phantom (1.18 g cm(-3)) 110 mm long, 110 mm wide, and 80 mm deep was used for phantom measurements. X-ray qualities were characterized by using 99.99% pure aluminum filters. On the basis of the IAEA's TRS 398, the article discusses the dependence of the plane-parallel ionization chamber readings with field size in air and in phantom, its implication with regard to clinical dosimetry, cross-calibration, and dissemination of calibration factors.     

应用电离室矩阵进行挡铅射野的验证的方法探讨

目的:探讨利用二维电离室矩阵MatriXX进行挡铅射野质量保证的方法及可靠性。方法:将治疗计划系统(TPS)中的铅块信息以dat的文件格式传递给Hek Medical System热丝切割机,根据dat文件做出相应的铅挡块,将铅挡块放至直线加速器的托架上,出束照射,用二维电离室矩阵MatriXX进行测量,从而获得挡铅射野的形状。应用matlab软件编程对由TPS导出的dat文件进行处理,绘制出射野在等中心平面处的形状和大小。将MatriXX电离室矩阵测得的射野的50%等剂量线和matlab绘制出的射野形状由photoshop软件进行比较分析。结果:笔者通过对20个TPS实测射野和计划射野的比较分析,发现二者总体上能够相符,只是在射野边缘尤其是连续变化的曲线边缘的细节表现上略微有些差异,它们综合位置差为0.631 mm,均方差为0.776 mm。结论:TPS实测射野和计划射野的吻合度非常高,基本满足放射治疗中对挡铅射野误差在5 mm以内的要求。     

The analysis of densitometry image of bone tissue based on computer simulation of X-ray radiation propagation through plate model

In this work, we have presented an attempt at the computer modelling of the attenuation effect of X-ray radiation which occurs in the densitometry test. The purpose of the modelling is to examine the extent to which the parameters of the plate model of bone tissue affect bone mineral density (BMD) parameter. In the modelling the fundamental functions realised by a densitometry device have been taken into consideration. Certain necessary assumptions simplifying the computation of the complex physical processes that occur during the transition of X-ray radiation through an object have been made. In order to compute the image produced by interaction of radiation the attenuation law is applied. The modelling of an object consists in defining its dimensions and its material characteristics. In the presented simulation the material characteristics of the object are limited to its attenuation coefficient. A different value of the coefficient can be defined for each voxel. The result image is produced by the calculation of partial attenuation in the individual voxels. The levels of grey in the image represent the value of the computed radiation intensity which is recorded in the "detector" after transition through the object. The simulation has been performed for the plate model representing trabecular bone tissue with 0.1mm porosity compartments. The results of the simulation of the plate model are presented. It can be observed that for certain modelled porosity compartments the size, structure and spatial arrangement are not properly recorded in the two-dimensional "detector". The recorded simulation results may be found useful for explaining difference that has been noticed between the BMD obtained from the densitometry test and the bone susceptibility to fracture.     

Radiation-induced cardiomyopathy as a function of radiation beam gating to the cardiac cycle

Portions of the heart are often unavoidably included in the primary treatment volume during thoracic radiotherapy, and radiation-induced heart disease has been observed as a treatment-related complication. Such complications have been observed in humans following radiation therapy for Hodgkin's disease and treatment of the left breast for carcinoma. Recent attempts have been made to prevent re-stenosis following angioplasty procedures using external beam irradiation. These attempts were not successful, however, due to the large volume of heart included in the treatment field and subsequent cardiac morbidity. We suggest a mechanism for sparing the heart from radiation damage by synchronizing the radiation beam with the cardiac cycle and delivering radiation only when the heart is in a relatively hypoxic state. We present data from a rat model testing this hypothesis and show that radiation damage to the heart can be altered by synchronizing the radiation beam with the cardiac cycle. This technique may be useful in reducing radiation damage to the heart secondary to treatment for diseases such as Hodgkin's disease and breast cancer.