GE 1.5 T HD核磁共振伪影等故障原因分析与处理

故障现象一所有线圈扫描出现干扰伪影. 故障分析及处理仔细观察发现所有线圈扫描均出现"水纹"状斜纹伪影,其中腹部图像伪影最明显,系统未提示错误.检查机房各附属设备无异常,水冷机工作正常,屏蔽间空调温度和湿度符合要求;磁体洞内未发现金属异物,考虑到可能系打火所致伪影.首先关闭屏蔽房内照明灯进行扫描;再关闭磁体上的冷头和磁体风扇进行扫描,伪影均依然存在;于是排查射频系统,依次重新连接射频放大部分的射频线缆及控制线,然后扫描,图像无变化;继而重新连接梯度放大部分的线缆,扫描,伪影消除,图像恢复正常.     

磁共振设备间动力配电柜维修一例

超导磁共振是医院的高精设备,其对电力的要求也相对严格,外电源的故障将直接影响磁共振的开机率及科室效益.下面分析1例由外电源(配电柜交流接触器)引发的故障. 1.故障现象及初步定位 今年3月,技师操作磁共振设备时发现机器总是在毫无征兆的情况下断电,紧接着操作台报警声响起,磁体间小鸟声消失意味着冷头没有工作,设备间水冷柜及梯度柜断电,稳压柜无输出,查看配电柜时,发现电压表指示Uab线电压410V,同时代表“停止”的带灯按钮开关亮起,代表“接通”的带灯按钮开关不亮.按下“接通”按钮后,稳压柜、梯度柜及冷水机柜相继得电,不久磁体间小鸟声响起,机器貌似正常,但还没有等技师重启操作台完成,设备又全部失电,故障现象同前.反复数次,最终宣告停机.     

磁共振中心频率漂移的调整

我院使用磁共振设备为美国ＦＯＮＡＲ公司生产ＢＥＴＡ30 0 0型 ,主磁体磁感应强度为 0 .3Ｔ ,质子的共振频率为 12 .77ＭＨｚ ,为永磁型磁共振成像系统。在扫描前 ,要对中心频率进行调整 ,对接收线圈的调谐与匹配以及增益进行调整。如果机器的中心频率产生漂移 ,系统将不能正常工作或图像质量变差。永磁系统对温度、湿度要求比较高 ,机房内温度要求保持在 2 2°( 2°/ 1°) ,温度变化大 ,会使系统的中心频率产生漂移 ,远离中心频率 (ｌａｒｍｏｒ) ,共振频率ｆ =ｒ·Ｂ0 (ｒ为氢核质子的旋磁比 42 .5 8ＭＨｚ/Ｔ ,Ｂ0 为主磁场强度 ) ,与…     

发光二极管应急照明在磁共振扫描室中的应用

磁共振扫描室与其他仪器设备室有所不同,在安装磁共振机时,首先要对磁共振扫描室做好磁屏蔽和射频屏蔽。磁共振成像扫描装置,磁体体积大,磁场强度高,周围环境中的铁磁材料会破坏磁体的均匀度,影响扫描图像的质量。强磁场本身也会影响周围环境,导致一些电气设备功能障碍。基于上述原因,磁共振扫描室均未安装配备应急照明设备,国内外也未见有安装配备应急照明设备的文献报道。而医院停电时有发生,如遇紧急事件时无法及时疏散受检者,更谈不上应急方案的实施。为了使应急照明设备能够在强磁场中使用,既不影响磁场的均匀度,又不使应急照明设备受到强磁场的损毁。我们在进行调查和分析后,选用发光二极管(LED)灯替代应急照明灯泡。应急照明设备安装于屏案,也可防止强磁场损毁应急照明设备,影响磁场均匀度,进而影响图像质量。经过实际应用,效果满意。应急照明设备工作原理是将输入电源,连接在磁共振设备控制机房照明220 V电源上,在磁共振控制机房照明220 V电源正常工作时,220 V电源给应急照明设备内蓄电池充电,应急照明灯处于关闭状态。一旦突发停电和发生紧急事件时,应急照明设备内电路自动切换,220 V电源由给蓄电池充电方式改为向LED灯提供6 V直流供电...     

GE 1.5T磁共振机冷头的相关故障

现代高场强超导磁共振机,其冷头的正常运转对磁体保持恒温有非常重要的作用,如果冷头较长时间停止工作会导致磁体温度上升液氦挥发,严重时会引起失超。我们科的GE1.5T双梯度核磁共振机在使用过程中就遇到2次与冷头停止工作的相关故障。故障一散热不良导致冷头停机一次扫描完病人后不到半小时,发现冷头无声音,压缩机不运行,MAGNETMONI TOR上显示压强为4.78PSIG(正常值为4.0PSIG),液氦面为70.2%(正常值为80%)。查看水冷机的INTERFACEOPER ATER发现显示屏左上侧红灯亮,进入DATA栏出现SUPPLY FAILURE,TEMERROR提示,…     

MR质量控制的现状和展望

本文综述了MR质量控制的发展史,分别就设备,磁体,成像参数,图像伪影等方面的质控发展现状进行综述,并进一步阐述了MR质控的发展及其重要性。     

核磁共振显像——基本原理(续一)

1.电磁波、磁场、磁体 在NMR中电磁波与磁场及磁体的概念是十分重要的。电磁波,顾名思义,是一种包含有电场和磁场的波形式,其中磁场强度的方向与电磁波的传播方向相垂直。每一电磁波都具有一     

MRI周围环境及辅助设备维护的探讨

MRI是随着计算机技术、电子技术及低温超导技术迅速发展起来的医学诊断技术,它既可提供形态学结构信息,也可提供生物化学及代谢信息,在当今医学诊断技术中占有绝对优势。磁共振成像系统是由磁体、射频和计算机及辅助设备所组成,每一组成部分都与最终的成像有着密切关系,为此,对MRI周围环境及辅助设备的维护与保养,是确保设备     

低磁场医用诊断磁共振设备运行中应注意问题

通常低场磁共振机 (0 .3T以下 )主要采用铁、钴镍金制成的永久磁体 ,它虽然重量大 (可达 10吨左右 ) ,对外界磁场的干扰和环境温度比较敏感 ,但由于永久磁体便于安装和匀场 ,运行成本低 ,易于人工控制和维护 ,成像质量较好等优点 ,深受广大用户欢迎。在低场磁共振机的运行过程中 ,我们必须充分重视磁场屏蔽和磁体恒温的问题 ,确保静磁场的均匀性和稳定性 ,以此获得满意的图像 ,达到良好的诊断效果。我院自 2 0 0 1年10月引进了美国GE公司生产的开放式低场永久磁体磁共振机 (SIGNA 0 2 3T) ,在 1年多的使用和运行过程中 ,积累了一点经验…     

浅谈现代大型影像设备维修的新理念与方法

根据新世纪影像设备数字化快速发展的情况 ,笔者提出了维修的新理念 ,一是变机器坏了后被动地去修理 ,为主动地加强机器的管理与日常维护 ,以杜绝故障的隐患 ,减少故障的发生率 ;二是要提高对计算机软件故障的处理能力。一、影像设备维护的基本方法以下根据笔者的经验 ,从温度、湿度、电源、防尘、异常情况、正确操作 6个方面 ,谈谈现代大型影像设备的维护方法。(1 )温度 :大型设备在工作时 ,一般会产生大量的热量 ,机器内温度很高 ,应及时地散发出去才行 ,另外温度过低也容易造成机器工作不正常。故机房内应配备空调 ,将温度控制在机器允许…     

Optimization of the system of medical service of students of Cadet Schools of the Ministry of Defense of the Russian Federation

One of the factors of the successful military career guidance Cadet schools students is preserving and promoting their health. Medical support of children and adolescents aged 10-17 years should include the full range of medical and preventive measures defined for this group. The state of providing outpatient care for pupils at the Cadet School in St. Petersburg was studied. These results show that full medical care in accordance with the standards can be based only on children's health clinics. It is important that the organization of medical support pupils cadet schools should be cooperate with civilian health care.     

带状疱疹83例误诊原因分析

带状疱疹是由水痘—带状疱疾病毒引起的皮肤科常见疾病。其主要的病理损害,一是受累神经的严重炎症性浸润,继而导致受侵犯神经节内神经细胞变性、坏死;二是皮肤的水泡。迅速抑制神经节和相应的感觉神经纤维的充血、水肿和坏死,防止粘连形成,达到迅速镇痛、改善皮损,缩短病程及防止后遗症的发生是治疗的关键。因而,尽早明确诊断,     

Estimation of accumulated dose of radiation by method of ESR-spectrometry of dental enamel of mammals

ESR-spectrometry was used to investigate radiation-induced paramagnetic centers in enamel of mammals: carnivores (polar bear and fox), ungulates (reindeer, European bison, moose), and man. Values at half the microwave power saturation of the radiation signal, P_1/2, evaluated at room temperature, was found to range from 16 to 26 mW for animals and man. A new approach to discrimination of the radiation induced signal from the total ESR spectrum of reindeer enamel is proposed. ‘Dose-response’ dependencies of enamel of different species mammals were measured within the dose range from 0.48 up to 10.08 Gy. Estimations of ‘radiosensitivity’ enamel of carnivores and ungulates showed good agreement with radiosensitivity enamel of man by ESR method.     

Analysis of the results of the international comparison of activity measurements of a solution of Fe

The results of an international comparison of activity measurements of a solution of ⁵⁵Fe organized by the BIPM in 2005 are reported and analysed. This exercise, which follows the procedures of the CIPM mutual recognition arrangement to update older comparisons, is a renewal of the comparison organized by the BIPM that took place in 1978. A EUROMET comparison was organized in 1996 specifically to compare activity measurements of a ⁵⁵Fe solution by means of liquid-scintillation techniques. Results of these three comparisons are presented and discussed in this paper.

The radionuclide solution was provided by the NPL, which also distributed the samples to the participants. The activity of the ampoules was measured by 16 laboratories using 12 methods producing 25 results. Some general considerations on uncertainty assessments pertaining to the different techniques used are drawn. The outcome of four different estimators is compared from which the presence of at least one outlier can be confirmed. Further measurements should be made to try to reduce the discrepancy between the results. To date the outcome of the present comparison does not show an improvement to that of the 1996 comparison.     

Evaluation of the results of various technics of non-surgical therapy of varicocele

A new method of non-surgical treatment of varicocele syndrome is described: it consists in sclerotherapy of spermatic vein by trans-femoral percutaneous catheterization with balloon-catheters. In 8 cases venous thrombosis has been induced by direct electric clotting. The techniques and a 6 months follow-up are discussed. It is pointed out that this procedure should be considered as the method of choice for tubular lesions and sub-fertility prophylaxis in young people and in childhood.     

延迟性脾破裂误漏诊原因分析

目的探讨延迟性脾破裂误漏诊原因和预防措施.方法回顾性分析总结12例延迟性脾破裂中的诊断和误漏诊的经验与教训.结果本组延迟性脾破裂的误漏诊5例(41.66%).对多发伤与脾破裂并存可能认识不足,外伤史轻微或伤员隐瞒外伤史,缺乏腹痛-缓解-突然再腹痛的典型病史,缺乏“对冲性脾破裂”力学分析和整体化诊断思路等为其误漏诊的主要原因.结论详细的外伤史和全面系统检查,重视腹以外多发伤掩盖腹内脏器伤及延迟性脾破裂可能.确立外伤-腹内脏器伤-脾破裂整体化诊断思路.不间断地辅以B超检查脾形态学变化和腹内有无积液,腹腔穿刺确定有无血腹、X线胸腹部检查观察左侧胸肋角和膈肌运动情况、必要时CT检查以尽早发现脾包膜下血肿,降低延迟性脾破裂误漏诊率.