一种半导体探测器在乳腺AEC中应用的初步研究

目的:研究一种有效面积为1 cm×1 cm的半导体探测器对钼靶X射线的响应情况、探测器的输出与胶片达到质控密度时所需曝光量的函数关系,以期将此探测器实际应用于高频乳腺X线摄影AEC控制系统中.方法:将探测器置于暗盒下部,焦片距63 cm,利用高频乳腺X线机分别在28 kV和35 kV管电压情况下对不同厚度组体模照射,测量探测器输出,分析探测器对经体模衰减后的软X射线响应情况;对不同厚度组体模阶梯状排列以不同摄影条件拍摄胶片、测量各阶梯对应密度值,分析在胶片密度为1.0和1.25时,体模厚度与所需曝光量的函数关系,再进一步分析设定密度时探测器输出值与所需曝光量的函数关系.结果:探测器输出与体模厚度之间符合V=V0e-cx函数关系;设定胶片密度时,探测器输出值与所需曝光量之间符合J=J0(V0)k/cV-k/c函数关系.结论:进行相应的电路和控制程序设计,可将此探测器应用于实际的高频乳腺X线摄影自动曝光控制系统中,实现管电压和mAs的自动控制.     

直接数字X射线摄影组织均衡技术在颈胸段摄影中的应用

背景:由于颈胸段侧位摄影时,成像区域的组织厚薄相差大,且重叠多,即使数字X射线摄影具有曝光动态范围大,图像能进行多种后处理的功能,但数字X射线摄影的常规摄影也难以显示颈胸段的解剖结构来了解病情,颈胸段正侧位数字X射线摄影影像质量需要进一步提高。目的:比较应用直接数字X射线摄影组织均衡技术产生的颈胸段图像和直接数字X射线摄影产生的标准数字X射线摄影图像的差别,在颈胸段摄影中探究最佳图像质量。方法:从解放军总医院放射科2005-04/2009-08所摄的数字X射线摄影颈胸段影像中按随机数字表法抽取200例作为分析资料,应用直接数字X射线摄影组织均衡技术对标准数字X射线摄影图像进行处理,比较组织均衡图像与标准数字X射线摄影图像的差别。结果与结论:应用直接数字X射线摄影组织均衡技术产生的新的图像,在同一幅图像上下颈上胸段的细节均可清晰显示;标准数字X射线摄影图像需要反复调节不同的窗宽、窗位才能清晰显示下颈上胸段的细节。提示在直接数字X射线摄影中,应用组织均衡技术能明显改善被检体受厚度影响而不容易观察的细节,同时,又不影响其他部位的细节显示。操作简便,可提高诊断率,减少误诊率,减少成本。     

数字X射线摄影机床边胸部摄影时周围散射线量测量

目的测量移动式数字X射线摄影（DR）机床边胸部摄影时照射野外的散射线辐射剂量。方法采用移动式DR机,用80kV、240mA、10ms和110cm焦-片距,垂直照射胸部体模,将测量仪分别放在360°均等分的8个角度、距照射野外1m和2m处,共测16个点。结果在0°和180°2m远距离处,测量仪上散射线量指示值最大,均为0.014μSv。在90°和270°2m远距离处最小,分别为0.011μSv和0.010μSv。结论一次移动式DR床边机胸部摄影,如患者和工作人员距照射野外2m远,其散射线辐射剂量低于人体7min所接受的自然本底照射剂量,不会产生危害后果。     

脊柱全景成像技术在脊柱侧弯摄影中的应用

目的探讨脊柱全景成像检查技术在脊柱侧弯摄影中的应用价值。方法采用Slot检查技术46例脊柱侧弯患者(A组),其中男性19例,女性27例;年龄11～18岁,平均年龄15岁。采用数字化X射线摄影(DR)拼接技术58例脊柱侧弯患者(B组),其中男性33例,女性25例;年龄10～19岁,平均年龄16岁。Slot检查技术,通过一次连续几秒曝光获得从颈椎上段至骶尾椎的脊柱全长影像,与行DR拼接技术(通过2次摄影2张X射线照片,经过剪切、重叠拼接成全脊柱片)进行比较。结果A组患者均一次性完成全脊柱摄影检查,颈、胸、腰、骶、尾椎同时在1张X射线照片上清晰显示,整个图像密度均匀,无拼接伪影。B组患者,23例因患者移动导致重拍,16例因照片拼接误差较大导致重拍,其余19例均一次完成检查。所摄X射线照片中,患者颈、胸、腰、骶、尾椎整体影像与图像细节均显示良好,全脊柱图像可见明显的拼接伪影。B组患者中长度拼接误差14例(24.1%),角度拼接误差49例(84.5%),图像后处理放大率不同拼接误差6例(10.3%)。结论采用Slot全脊柱摄影对脊柱侧弯患者进行术前检查,与过去的DR拼接摄影法相比,不但能够清晰地显示脊柱全长影像,同时极大地提高了测量精度,保证了全幅图像密度均匀一致,对脊柱侧弯患者进行术前计划具有重要的临床意义与应用价值。     

CR静脉肾盂造影图像质量与X射线剂量的探讨

目的探讨计算机X射线摄影（CR）在静脉肾盂造影应用中以满足图像诊断质量和X射线曝光参数（kVp、mAs）的优化组合,使X射线剂量控制在最低,降低被检者的有害X射线辐射量。方法对3组不同体型厚度（18cm、22cm、26cm）的被检者,对每组分别以常规摄影条件,增加kVp、降低mAs进行摄影。以kVp与mAs组合图像质量完全满足诊断要求,剂量最低的参数作为最优参考曝光参数。用体模替代3种被检者体型厚度,用同样摄影曝光参数,分别测量体表、体后及有关被检者器官组织的吸收X射线剂量。结果与常规摄影相比,被检者的X射线吸收剂量平均降低了31.97%,面积乘积剂量平均降低了34.57%,有效剂量降低了33.98%。结论在静脉肾盂造影中用CR成像技术与投照参数优化组合,对降低被检者的X射线吸收剂量是行之有效的,为其他投照部位用CR或数字X射线摄影（DR）数字成像参数优化组合研究提供了指导性的方法,有一定的临床应用价值。     

对比常规X射线与X射线数字断层融合技术用于骶尾骨侧位摄影中的价值

目的对比分析常规X射线摄影与X射线数字断层融合技术(DTS)在骶尾骨侧位摄影中的应用价值。方法选择2014年3月至2015年1月南方医科大学南方医院就诊的疑有骶尾骨病变患者214例,其中男性98例,女性116例;年龄38~59岁,平均年龄43.2岁。先后进行常规X射线摄影和DTS,比较两种成像技术获得的骶尾骨图像质量。结果 DTS诊断,骶尾骨骨折患者121例,骶尾骨脱位患者27例;常规X射线摄影诊断,骶尾骨骨折患者91例,骶尾骨脱位患者31例,漏诊45例,误诊9例。DTS的图像优秀率高达93.0%,常规X射线摄影技术中的图像优秀率为50.0%。DTS图像比常规X射线摄影图像的清晰度高、对比度明显。常规X射线摄影像图像骶尾骨结构显示不清晰,难以确定骨折或脱位,易发生漏诊。结论 DTS可以多方位、多层面地获得清晰度高、对比度明显的骶尾骨图像,满足临床诊断的需求,从而避免误诊和漏诊,具有较高的临床应用前景。     

内斜位X线片显示股骨距影像特征及其临床意义

目的:研究内斜位X线片上股骨距的形态特征,探讨内斜位片显示股骨距的临床意义。方法:用成人干燥股骨标本143根,进行内斜位拍片,对股骨距影像进行测量分析,根据其特点进行分型。结果:在内斜45°X线片均观察到完整股骨距影像(100%),主要由线形的致密的皮质骨和密集的松质骨小梁组成。股骨距长度INL为(4.36±0.46、)cm。股骨距分为:弧线型,29.5％(42例);骨小梁型,21.6％(31例);断线型,27.3％(39例);融合型,21.6％(31例)。结论:内斜45°X线片显示股骨距影像清晰恒定。股骨距是股骨颈干交界后内侧重要的支撑结构,股骨上段疾病患者应常规加拍内斜位X线片,观察股骨距变化,决定诊疗方案。     

GE AMX-4Plus移动X射线机的数字化X射线摄影改造

目的为了提高床旁X射线摄片的图像质量,对现有移动X射线机GEAMX-4Plus进行数字化X射线摄影（DR）改造,由原来影像板（IP）成像再行计算机X射线摄影（CR）扫描获得图像的方式改为DR直接摄片。方法以移动X射线机为基础．配置Pixium3543无线平板系统．设计基于该平板的数字摄影操作平台系统和曝光同步控制系统。结果DR改造后,移动X射线机可以正常使用,性能稳定,图像质量较以前CR模式得到大幅提高,获得临床认可。结论数字化x射线摄影改造既使原有移动X射线机得到充分的利用,也使床旁摄片质量、临床诊断及时性、准确度等方面得到大幅提高。     

采用分段摄影法让无全脊柱摄影功能的DR实现全脊柱成像的方法探讨

目的 探讨数字X射线摄影(DR)技术在全脊柱摄影中的应用.方法 在用DR对脊柱分段摄影的图像基础上,利用后处理工作站图像拼接软件进行人工拼接处理,同时全景显示人体脊柱的形态.结果 经过几十例试验,图像效果优于计算机X射线摄影(CR),在临床上被采用.结论 利用DR做全脊柱摄影完全可行,而且不仅可以看大体结构,还能观察局部.     

基于普通床旁机和无线平板探测器婴儿数字胸部X射线摄片技术初步研究

目的探讨联合应用无线平板探测器(无线DR板)和普通移动床旁摄片机实现婴儿数字化胸部X射线摄片的技术可行性。方法选择2017年11月至2018年3月上海市儿童医院重症监护病房(ICU)258例患儿,其中男性179例,女性79例;年龄1天～3岁。使用普通移动床旁摄片机和无线小尺寸DR板,进行床边胸X射线摄片检查。研究无线传输图像的可行性,由3名诊断医生对图像质量分别进行评估。结果所有检查均1次成功完成,技术成功率为100%。曝光参数均在原设定基础上减少2～3 kV及0.3～0.5 mAs;无线路由器均(100%)成功远程接收患儿放射科信息管理系统(RIS)信息并实时发送数字图像至影像归档和通信系统(PACS),未出现检查相关并发症。3名诊断医生甲级片分别为79.84%、87.21%、85.66%,乙级片分别为19.77%、12.02%、13.95%,丙级片分别为0.004%、0.008%、0.004%,废片为0。结论联合应用无线小尺寸DR板和普通移动床旁摄片机进行婴儿床边数字胸部X射线摄片检查技术可行,实现了普通移动床旁摄片机直接数字化X射线摄影的改造。     

基于LabVIEW的X射线机电源电阻测量设计

目的:为降低测量仪器系统误差噪声干扰的影响，准确测量X射线机电源电阻，设计一套X射线机电源电阻测量程序。方法:在信号注入法测电阻的基础上，利用LabVIEW软件和NI公司生产的信号调理模块，设计电源内阻测量程序，该程序可产生稳定的正弦激励电流，并对响应电压、响应电流以及相位差进行测量，进而得到X射线机电源电阻值。结果:经系统测试可知，该测量程序可以对X射线机电源电阻进行一段时间内的连续测量，得到的电源电阻均值更接近实际状况。结论:该测量程序能够准确测量X射线机电源电阻，为准确测量X射线机电源电阻提供了一种新的方法和思路。 【关键词】X射线机；电源电阻；LabVIEW     

An improved image display for early E.M.I. scanners

First generation EMI head scanners have a poor image display and photography system. This paper describes how an image converter is interfaced to the EMI viewer console to produce a standard television image. The design also incorporates a multi-image photography unit to allow photographing of up to nine images on one standard X-ray film. The converted system's advantages are: a bright and stable display, reduced operator time, and significant material savings.     

拼接法全脊柱摄影外固定架的设计和自制

目的为部分有全脊柱摄影需求、但无该功能设备的医院介绍一种简易全脊柱摄影外固定架的自制,帮助其低成本实现全脊柱（长骨）摄影功能。方法采用不锈钢钢管、有机玻璃、玻纤板、报废X射线机的床面板等、带锁止的万向轮等,底座长宽各为60cm、高8cm的扁盒子,放填充物,提高稳定性。底座下面四个角安装带锁止万向轮。在底座上面四角上竖固定外径为40 mm的不锈钢管,高度约1.8 m,顶端焊成正方形,其中2根用于固定背板,另外2根为被检者上臂平前伸时手握。选择236例摄全脊柱片患者,其中男性158例,女性78例,年龄7～76岁。使用该固定架,进行数字X射线摄影（DR）。结果利用该外固定架,已摄影200余例,成像质量优于计算机X线摄影单次曝光拼接法。其中3例因患者年龄太大有少许左右移动错位外,其他全部合格,优秀率73%;曝光量设定错误,全片存在密度差异4例,但不影响诊断。结论对无全脊柱摄影功能的DR来说,只要有含拼接功能的工作站,利用自制外固定架,也能得到优质的全脊柱图像。     

Characterization of megavoltage electron beams delivered through a photon multi-leaf collimator (pMLC)

A study is presented that characterizes megavoltage electron beams delivered through an existing double-focused photon multi-leaf collimator (pMLC) using film measurements in a solid water phantom. Machine output stability and linearity were evaluated as well as the effect of source-to-surface distance (SSD) and field size on the penumbra for electron energies between 6 and 18 MeV over an SSD range of 60-100 cm. Penumbra variations as a function of field size, depth of measurement and the influence of the jaws were also studied. Field abutment, field flatness and target coverage for segmented beams were also addressed. The measured field size for electrons transported through the pMLC was the same as that for an x-ray beam up to SSDs of 70 cm. At larger SSD, the lower energy electron fields deviated from the projected field. Penumbra data indicated that 60 cm SSD was the most favourable treatment distance. Backprojection of P(20-80) penumbra data yielded a virtual source position located at 98.9 cm from the surface for 18 MeV electrons. For 6 MeV electrons, the virtual source position was at a distance of 82.6 cm. Penumbra values were smaller for small beam slits and reached a near-constant value for field widths larger than 5 cm. The influence of the jaws had a small effect on the penumbra. The R90 values ranged from 1.4 to 4.8 cm between 6 and 21 MeV as measured at 60 cm SSD for a 9 x 9 cm2 field. Uniformity and penumbra improvement could be demonstrated using weighted abutted fields especially useful for small segments. No detectable electron leakage through the pMLC was observed. Bremsstrahlung measurements taken at 60 cm SSD for a 9 x 9 cm2 field as shaped by the pMLC compared within 1% to bremsstrahlung measurements taken at 100 cm SSD for a 10 x 10 cm2 electron applicator field at 100 cm SSD.     

The technique for application of measuring ruler for karyometry.

A technique for measuring sectional plane of nuclei with the help of measuring ruler is described. The ruler may be of any transparent or opaque material with contours of measuring figures plotted on it. The area of the latter corresponds to that of nuclei projection maximal for this or that class under definite magnification. The article comprises also calculations of classes of nuclei, areas of measuring figures. The process of measurement consists in confrontation of the projection of the nucleus under study with measuring figures plotted on the measuring ruler in strict sequence from a smaller figure to bigger one.     

The use of new GAFCHROMIC EBT film for 125I seed dosimetry in Solid Water phantom

Radiochromic film dosimetry has been extensively used for intravascular brachytherapy applications for near field within 1 cm from the sources. With the recent introduction of new model of radiochromic films, GAFCHROMIC EBT, with higher sensitivity than earlier models, it is promising to extend the distances out to 5 cm for low dose rate (LDR) source dosimetry. In this study, the use of new model GAFCHROMIC EBT film for 125I seed dosimetry in Solid Water was evaluated for radial distances from 0.06 cm out to 5 cm. A multiple film technique was employed for four 125I seeds (Implant Sciences model 3500) with NIST traceable air kerma strengths. Each experimental film was positioned in contact with a 125I seed in a Solid Water phantom. The products of the air kerma strength and exposure time ranged from 8 to 3158 U-h, with the initial air kerma strength of 6 U in a series of 25 experiments. A set of 25 calibration films each was sequentially exposed to one 125I seed at about 0.58 cm distance for doses from 0.1 to 33 Gy. A CCD camera based microdensitometer, with interchangeable green (520 nm) and red (665 nm) light boxes, was used to scan all the films with 0.2 mm pixel resolution. The dose to each 125I calibration film center was calculated using the air kerma strength of the seed (incorporating decay), exposure time, distance from seed center to film center, and TG43U1S1 recommended dosimetric parameters. Based on the established calibration curve, dose conversion from net optical density was achieved for each light source. The dose rate constant was determined as 0.991 cGy U(-1)h(-1) (+/-6.9%) and 1.014 cGy U(-1)h(-1) (+/-6.8%) from films scanned using green and red light sources, respectively. The difference between these two values was within the uncertainty of the measurement. Radial dose function and 2D anisotropy function were also determined. The results obtained using the two light sources corroborated each other. We found good agreement with the TG43U1S1 recommended values of radial dose function and 2D anisotropy function, to within the uncertainty of the measurement. We also verified the dosimetric parameters in the near field calculated by Rivard using Monte Carlo method. The radial dose function values in Solid Water were lower than those in water recommended by TG43U1S1, by about 2%, 3%, 7%, and 14% at 2, 3, 4, and 5 cm, respectively, partially due to the difference in the phantom material composition. Radiochromic film dosimetry using GAFCHROMIC EBT model is feasible in determining 2D dose distributions around low dose rate 125I seed. It is a viable alternative to TLD dosimetry for 125I seed dose characterization.     

The spherically averaged structures of cowpea mosaic virus components by X-ray solution scattering

The X-ray diffraction patterns of the four components of cowpea mosaic virus isolated from a cesium chloride gradient were measured, using film methods, to 30 A resolution. Diffraction patterns were analyzed by fitting computed two-shell spherical models to the observed data. The fitting procedure was applied to data to 80 A resolution to avoid the nonspherical contribution to the pattern observed at higher resolution. At pH 7.0 all four components displayed the same external spherically averaged radius of 140 +/-2 A. The lowest density component (top), which contains no RNA, was best modeled by an empty shell with an outer radius of 140 A and an inner radius of 101 +/- 3 A. The middle component, containing 27% RNA by weight, was modeled with a uniform electron density sphere. The bottom upper and bottom lower components, which are biologically identical but display different buoyant densities in cesium chloride solutions, were analyzed independently. The bottom upper component was best modeled with a 101 A inner (RNA containing) sphere of mean electron density 0.453e-/A(3) and a 101 to 140 A outer (protein containing) shell of electron density 0.410e-/A(3). The bottom lower component was fit with the same model except that the RNA containing region displayed a mean electron density of 0.459e-/A(3). The implications of the spherically averaged component structures for the protein structure, RNA and protein hydration, and cesium binding to RNA are discussed.     

Optimal sensitometric curves of Kodak EDR2 film for dynamic intensity modulated radiation therapy verification

Purpose:

To investigate the optimal sensitometric curves of extended dose range (EDR2) radiographic film in terms of depth, field size, dose range and processing conditions for dynamic intensity modulated radiation therapy (IMRT) dosimetry verification with 6 MV X-ray beams.

Materials and methods:

A Varian Clinac 23 EX linear accelerator with 6 MV X-ray beam was used to study the response of Kodak EDR2 film. Measurements were performed at depths of 5, 10 and 15 cm in MedTec virtual water phantom and with field sizes of 2x2, 3x3, 10x10 and 15x15 cm². Doses ranging from 20 to 450 cGy were used. The film was developed with the Kodak RP X-OMAT Model M6B automatic film processor. Film response was measured with the Vidar model VXR-16 scanner. Sensitometric curves were applied to the dose profiles measured with film at 5 cm in the virtual water phantom with field sizes of 2x2 and 10x10 cm² and compared with ion chamber data. Scanditronix/Wellhofer OmniPro^TM IMRT software was used for the evaluation of the IMRT plan calculated by Eclipse treatment planning.

Results:

Investigation of the reproducibility and accuracy of the film responses, which depend mainly on the film processor, was carried out by irradiating one film nine times with doses of 20 to 450 cGy. A maximum standard deviation of 4.9% was found which decreased to 1.9% for doses between 20 and 200 cGy. The sensitometric curves for various field sizes at fixed depth showed a maximum difference of 4.2% between 2x2 and 15x15 cm² at 5 cm depth with a dose of 450 cGy. The shallow depth tended to show a greater effect of field size responses than the deeper depths. The sensitometric curves for various depths at fixed field size showed slightly different film responses; the difference due to depth was within 1.8% for all field sizes studied. Both field size and depth effect were reduced when the doses were lower than 450 cGy. The difference was within 2.5% in the dose range from 20 to 300 cGy for all field sizes and depths studied. Dose profiles measured with EDR2 film were consistent with those measured with an ion chamber. The optimal sensitometric curve was acquired by irradiating film at a depth of 5 cm with doses ranging from 20 to 450 cGy with a 3×3 cm² multileaf collimator. The optimal sensitometric curve allowed accurate determination of the absolute dose distribution. In almost 200 cases of dynamic IMRT plan verification with EDR2 film, the difference between measured and calculated dose was generally less than 3% and with 3 mm distance to agreement when using gamma value verification.

Conclusion:

EDR2 film can be used for accurate verification of composite isodose distributions of dynamic IMRT when the optimal sensitometric curve has been established.     

Dosimetric properties of an amorphous silicon electronic portal imaging device for verification of dynamic intensity modulated radiation therapy

Dosimetric properties of an amorphous silicon electronic portal imaging device (EPID) for verification of dynamic intensity modulated radiation therapy (IMRT) delivery were investigated. The EPID was utilized with continuous frame-averaging during the beam delivery. Properties studied included effect of buildup, dose linearity, field size response, sampling of rapid multileaf collimator (MLC) leaf speeds, response to dose-rate fluctuations, memory effect, and reproducibility. The dependence of response on EPID calibration and a dead time in image frame acquisition occurring every 64 frames were measured. EPID measurements were also compared to ion chamber and film for open and wedged static fields and IMRT fields. The EPID was linear with dose and dose rate, and response to MLC leaf speeds up to 2.5 cm s(-1) was found to be linear. A field size dependent response of up to 5% relative to dmax ion-chamber measurement was found. Reproducibility was within 0.8% (1 standard deviation) for an IMRT delivery recorded at intervals over a period of one month. The dead time in frame acquisition resulted in errors in the EPID that increased with leaf speed and were over 20% for a 1 cm leaf gap moving at 1.0 cm s(-1). The EPID measurements were also found to depend on the input beam profile utilized for EPID flood-field calibration. The EPID shows promise as a device for verification of IMRT, the major limitation currently being due to dead-time in frame acquisition.     

不同电极距离下人体小腿组织细胞内外液电阻率的测量

目的观察不同电极距离下人体小腿细胞内外液电阻率的均匀性,探究测量系统的可行性,以便应用此系统测量健康信息。方法采用四电极生物阻抗谱法,激励电极将1~100 kHz恒流电流施加到人体小腿两端,测量电极采集电压和相角,电极距离分别为5 cm、10 cm、15 cm。测量10例健康受试者,计算得到细胞内外液的阻抗值和电阻率。结果随两电极间距离的增加,细胞内外液阻抗均极显著增加,阻抗的增加与距离高度相关;细胞内外液电阻率随距离仅有小幅增加,5 cm和15 cm之间有显著性差异,与小腿有效截面积随距离缩小有关。细胞内外液电阻率之比接近1,且不随电极距离的变化而改变。结论健康人体小腿组织的电阻率比较均匀,细胞内外液电阻率基本相等。