宽排CT探测器CT剂量指数应用初探

目的:随着射线宽度的不断增加,传统CT剂量指数(CTDI)在表征CT剂量时遇到瓶颈问题,不能够很好地表征宽排CT探测器的剂量水平。本文探讨CTDI在CT宽排探测器剂量表征量方面的概念演化和应用方式。方法:介绍传统CTDI表征CT剂量的原理和方式,展示传统CTDI在表征宽排CT探测器时的局限性,阐述宽排CT探测器CTDI剂量表征量方式的演变过程,初步探讨宽排CT探测器CTDI表征和测量。结果:IEC在对传统CTDI进行修正的基础上推出分层次CTDI表征的方式,能更好适应宽排CT探测器的剂量表征。通过多点分次测量,新定义的分层次CTDI仍然可采用传统的150mm有机玻璃CT剂量体模和100mm电离室进行测量。结论:分层次CTDI表征方式能在保留传统CTDI基本概念和常规测试条件的基础上较好地表征宽排CT探测器的剂量水平。     

Caries-removal effectiveness and minimal-invasiveness potential of caries-excavation techniques: a micro-CT investigation

Objectives

To determine the caries-removal effectiveness (CRE) and minimal-invasiveness potential (MIP) of contemporary caries-removal techniques.

Methods

Carious molars were scanned using micro-CT, after which dentine caries was removed by 9 contemporary caries-removal techniques. The micro-CT was repeated and CRE was determined on basis of the relative volume of residual caries and the mineral density (MD) at the cavity floor. MIP was determined by measuring the cavity size relative to the initial size of the caries lesion.

Results

CRE and MIP varied most for the Er:YAG laser (Kavo) despite its laser-induced fluorescence (LIF) feedback system. Whilst some specimens revealed much residual caries, others showed over-excavation into sound dentine. With the highest Relative Cavity Size, the Er:YAG laser presented the lowest MIP. Rotary/oscillating instruments revealed a more favourable CRE with some tendency towards over-excavation, except for CeraBur (Komet-Brasseler) and Cariex (Kavo) that typically left caries at the cavity floor and cavity walls, respectively. Chemo-mechanical excavation aided by conventional metal excavators (Carisolv, MediTeam; exp. SFC-V and SFC-VIII, 3M-ESPE) combined best CRE with MIP. When however a plastic excavator was used along with exp. SFC-VIII, caries was less completely removed.

Significance

Er:YAG-laser aided by LIF resulted in non-selective caries removal. Rotary/oscillating caries removal may lead to over-excavation, especially when burs are combined with Caries Detector (Kuraray). This risk for over-excavation is reduced when a tungsten-carbide bur is solely used. On the contrary, Cariex (Kavo) and CeraBur showed a tendency for under-preparation. Chemo-mechanical methods were most selective in removing caries, whilst preserving sound tissue.     

Coronary artery stent imaging with CT using an integrated electronics detector and iterative reconstructions: First in vitro experience

BackgroundDespite continuous improvements in CT technology, accurate stent lumen delineation remains challenging.PurposeThe aim was to evaluate the quality of coronary stent lumen delineation with CT using a detector with integrated electronics.MethodsTwelve coronary stents placed in plastic tubes and filled with contrast agent (CT number 250 HU) were imaged with either a 128-section dual-source CT machine equipped with conventional detector or with integrated electronics. On both scanners, images were reconstructed with filtered back projection (slice thickness 0.6 mm; increment 0.4 mm) and sinogram-affirmed iterative reconstruction (slice thickness 0.6 mm; increment 0.4 mm), and with iterative reconstruction (slice thickness 0.5 mm; increment 0.3 mm) on the integrated scanner. Two blinded, independent readers assessed image quality, noise, in-stent diameter, in-stent attenuation, and image sharpness by using signal intensity profiles across stents.ResultsInterreader agreement for image quality assessment was substantial (κ = 0.798). Both readers rated best image quality in data sets from integrated detector at highest spatial resolution (86 or 72% of stents rated best quality). Image noise was significantly lower in data sets scanned with integrated detector, being lowest at 0.6 mm slice thickness (14.3 vs 21.0 HU; P < .001). Differences between measured and true in-stent diameters and differences in attenuation across stents were smallest, and average/maximum image sharpness was highest in data sets from the integrated detector using iterative reconstructions.ConclusionCT coronary stent imaging is significantly improved by using a detector with integrated electronics combined with iterative reconstructions.     

Differential striatal levels of TNF-alpha, NFkappaB p65 subunit and dopamine with chronic typical and atypical neuroleptic treatment: role in orofacial dyskinesia

Long term use of typical neuroleptics such as haloperidol may be limited by unwanted motor side effects like tardive dyskinesia characterized by repetitive involuntary movements, involving the mouth, face and trunk. Atypical neuroleptics, such as clozapine and risperidone are devoid of these side effects. However the precise mechanisms of the neuronal toxicity induced by haloperidol are poorly understood. It is possible that typical and atypical antipsychotic differently affects neuronal survival and death and that these effects considerably contribute to the differences in the development of TD. The aim of the present study is to investigate the role of TNF-alpha and NFkappaB on the toxicity induced by chronic haloperidol administration in an animal model of tardive dyskinesia. Rats were treated for 21 days with: haloperidol (5 mg/kg), clozapine (5 and 10 mg/kg), risperidone (5 mg/kg) or saline. Orofacial dyskinetic movements and total locomotor activity was evaluated. Striatal levels of dopamine were measure by HPLC/ED whereas striatal levels of TNF-alpha and NFkappaB p65 subunit were measured by ELISA technique. Haloperidol increased orofacial dyskinetic movements and total locomotor activity (on day 22) (P相似文献   

河北省多排探测器CT辐射剂量调查研究

目的通过了解河北省多排探测器CT（MDCT）扫描患者辐射剂量现状,为做好患者剂量控制和管理工作提供科学依据。方法按照国家标准GB 17589-2011、GBZ 165-2005规定的方法,对该省MDCT患者头颅、胸部、腹部、腰椎等典型部位的辐射剂量进行调查研究。结果有12台设备头颅CD加权剂量指数（CTDIW）超过了50 mGy,占总数的13.3%。腹部的最大CTDIW超过了诊断参考水平近2倍。各部位CTDIW最大和最小值相差很大,腰椎相差近20倍。头颅的剂量长度乘积（DLP）最高达1 455 mGy/cm,是国际原子能机构（IAEA）研究数据的2.8倍,是欧洲MDCT诊断参考水平的4.3倍。64排及以上机型剂量指数整体比16排要低。在其他扫描条件不变时,CT容积剂量指数（CTDIVOL）随m As变化呈正比,随电压增加而增大,随准直宽度的增大而减小,随螺距的增大呈反比下降。结论应按辐射防护正当化和最优化的原则,加强MDCT患者辐射剂量控制及相关人员的技术培训和继续教育。     

应用Detector729的两种IMRT剂量验证方法比较

目的：比较、分析Detector729用于IMRT质量控制的两种剂量验证方法。方法用Pinnacle 8.0 m计划系统对13例肿瘤患者做IMRT治疗计划,根据Detector729的CT扫描图像,分别做出实际机架角和0＆#176;机架角的验证计划,并在Varian 23EX加速器上实施剂量验证;依据剂量偏差（距离偏差）分别为3%（3 mm）、3%（4 mm）和4%（4 mm）的判定标准,得到两种验证方法的γ验证通过率,采用SAS统计学软件对验证结果进行分析。结果 Detector729两次测量的重复性均＜0.3%;应用Detector729对IMRT实际机架角验证3%（3 mm）、3%（4 mm）和4%（4 mm）的平均通过率分别为91.2%、92.4%和95.6%,较0＆#176;机架角计划验证通过率分别低了2.2%（t=-2.04,P=0.053）、2.2%（t=-2.02,P=0.055）和1.4%（t=-1.97,P=0.060）,两种剂量验证方法的通过率差异无统计学意义。结论 Detector729测量结果可信、准确;实际照射剂量验证和0＆#176;机架角剂量验证均与验证计划剂量分布基本一致;建议医疗机构采取符合实际治疗情况的剂量验证方法。     

探测器位姿对三维CT重建图像质量的影响分析

分析了探测器位姿误差对三维CT重建图像质量的影响,计算机模拟和MTF曲线对比结果表明:探测器沿x、y、z方向的位移不会对重建质量产生影响,只影响断层的位置.而其绕x、y、z三坐标轴的摆动会对重建图像质量造成影响,偏摆角控制在±0.2°以内、俯仰角控制在±1.0°以内、扭转角控制在±0.4°以内即可满足重建图像的质量要求...     

不同探测器测量射波刀输出因子比较分析

目的 比较分析5种不同探测器测量射波刀输出因子,以选择适合的探测器。方法分别使用电离室探测器PTW30013、PTW31010,半导体探测器PTW 60017、60018,宝石探测器PTW60019及EBT3胶片测量射波刀12个孔径准直器的输出因子。比较分析不同探测器及探测器放置方向测量的输出因子。结果 准直器孔径>30 mm时5种探测器测量的输出因子差异<1%,准直器孔径<30 mm时不同探测器测量结果差异较大,准直器孔径越小差异越大。与胶片测量结果比较,PTW60019与胶片的一致性最好,偏差<2%。半导体探测器测量结果稍高,电离室探测器测量结果过小。探测器放置方向不同,输出因子测量结果不同。PTW60019探测器平行射野中心轴放置时,测量的输出因子比垂直射野中心轴放置的结果偏低,PTW31010探测器测量结果相反。结论 准直器孔径>30 mm时PTW31010、PTW60017、60018及PTW60019可直接用于射波刀输出因子测量,准直器孔径<30 mm时需要对上述探测器的测量结果进行修正。PTW30013不适合小野输出因子测量。     

HPLC-PDA法检测蒲黄和黄连中十种非法添加色素

目的:建立HPLC-PDA法测定蒲黄和黄连中非法添加色素金橙G、日落黄、金橙Ⅰ、亮黄、甲基橙、金橙Ⅱ、金橙Ⅳ、金莲橙G、金胺O、二甲基黄的方法。方法:样品用70%乙醇溶液提取,以甲醇-0.05 mol/L醋酸铵溶液梯度洗脱,二极管阵列检测器检测。结果:该方法检出限为0.026 mg/kg~0.950 mg/kg,2档添加回收率为81.5%~104.7%;市售蒲黄和黄连中多批次检出金胺O。结论:本实验采用HPLC-PDA法同时检测蒲黄和黄连等黄色类中药材(饮片)中十种常用的非法添加色素,方法简单、准确、快速,可以为制药企业或药品监督管理部门控制蒲黄和黄连的质量提供一定的参考。