F99-ⅢA型X线机故障检修一则

故障现象 开机后透视正常,摄片时各继电器工作程序正常,但mA表指示时有时无,实测X线也时有时无。     

F99-Ⅳ型500mA X线机复合故障检修分析

故障现象　本机安装调试时 ,常规摄影条件下曝光 ,听到自耦变压器发出异常“咚咚”声 ,电源指示不稳 ,ｍＡ指示低于正常 ,严重时电源保险丝熔断 ,同时曝光时间比预置时间明显延长。故障检修与分析　打开控制台 (ＦＳＫ30 2 - 1型 ) ,拆下高压初级ＪＸ4- 6、ＪＸ4- 8,接上 1只 10 0Ｗ灯泡做假负载。试曝光时 ,发现灯泡亮但闪烁 (将摄影ｋＶ调高 ,时间设置较长些 ,其现象会更明显 ) ,这表明灯泡的供电电压不稳。用短路线跨接于主控硅ＢＧ94、ＢＧ95两端再试 ,灯泡亮度稳定无闪烁 ,表明两主控硅导通不良。用万用表查其触发电路及其他相关电路均…     

F30-IIG型X线机故障检修一则

故障现象 开机各仪表指示正常,透视曝光时mA大小可调,mA表指针颤动,荧光屏闪烁,床上球管摄片时一切正常。     

日立DR-150型X线机故障检修

我院1997年使用日立工频500mA拍片机,近期出现故障。故障现象:开机后控制面板技术选择、工作状态、曝光参数等无任何显示。半小时左右控制面板显示恢复正常,但大多数情况下机器不曝光,即使偶尔曝光,显示的曝光量mAs值也偏高且不稳定。曝光几次后再曝光时显示故障代码“E08”,示为摄影过电流。调节kV选择自耦变压器碳轮及控制面板显示无反应。故障分析与检修:摄影过电流分为高压系统过电流(包括X线管,高压发生器、高压电缆击穿等引起的过流)以及低压电路短路、元件击穿等形成的过流。排除高压系统故障后打开控制台前盖查看低压电路,发现自…     

F125-Ⅰ型X线机控制台故障1例

故障现象:开机,控制台面板上过载指示灯亮,曝光无法进行. 故障检修,根据故障现象,首先检查过载板(O板),因为过载继电器JO采用的是小型封装式继电器,无法准确判断其工作情况,故采用排除法,依次将二极管D1-18、D1-19、D1-20焊开,以判断故障所在电路.检修时发现即使三个二极管都断开后,故障现象仍然存在,根据这种情况可以判断JO并没有工作,故障不在过载板上.     

岛津MUX-100DJ移动式X线机故障维修

故障现象:本院使用的岛津MUX-100DJ移动式数字X线机已投入使用多年,近期在长距离连续行走时,频繁发生动力系统紧急停车现象,并于仪表板显示故障代码D1;如果将机器断电关机后重新开机,则暂时恢复正常运行,但再次行走距离较长时仍会发生此故障.     

Pharmacokinetic characteristics of 99mTc-Ethylene-l-dicysteine (99mTc-EC)

BACKGROUND: Ethylenedicysteine-99mTc (99mTc-EC) has been more and more commonly applied in dynamic studies as well as for clearance determinations. However, it was necessary to investigate in detail the pharmacokinetic characteristics of the radiopharmaceutical which may be important for its applicability in assessment of renal function. RESULTS: Kidney images obtained from renoscintigraphy are characterised by excellent quality without visualisation of the organs adjacent to kidneys (liver, spleen). Renoscintigraphic curves demonstrate typical shapes with TMAX and T1/2 values not differing from the corresponding values obtained for other radiopharmaceuticals (99mTc-MAG3, 131I-OIH). In plasma, 99mTc-EC binds with proteins to a considerably lesser degree (c. 1/3) than 131I-OIH (c. 2/3), or 99mTc-MAG3 (> 9/10). No binding of 99mTc-EC with erythrocytes has been demonstrated, whereas 131I-OIH attaches to or penetrates the red blood cells (10-12%). 99mTc-EC is quickly excreted from the organism: 40 min after i.v. injection up to 70% of the administered radiopharmaceutical is found in urine, and at 1 and 1.5 h after the administration 80% and 95%, respectively. The distribution of 99mTc-EC in the organism can be described in a fully satisfactory way by means of an open two-compartment model, which allows this model to be used for clearance determinations. Comparison of the values of renal plasma clearance without collection of urine with the values determined by means of measurement of activity excreted with urine and mean blood concentration over a finite time interval leads to the conclusion that extrarenal plasma clearance of this compound (via the liver?) is negligible and amounts to c. 17 ml/min (5-6% of the total). The obtained correlation between clearance values for 99mTc-EC and 131I-OIH supports the contention that extrarenal excretion rate of 99mTc-EC (through the liver and bile ducts) is lower than the corresponding rates of either 131I-OIH or 99mTc-MAG3. A very close correlation between clearance values for 99mTc-EC and ERPF (131I-OIH clearance) and between their extraction constants (r = 0.91 and 0.92, respectively), allows for the introduction of 99mTc-EC to the assessment of renal function instead of 131I-OIH. Effective dose to the patient from unit activity of 99mTc-EC is comparable with that resulting from administration of other radiopharmaceuticals labelled with 99mTc.     

99Tcm标记人源化抗人血小板膜糖蛋白Ⅲ a单克隆抗体SZ21F(ab)2血栓栓塞显像

目的用动物血栓栓塞模型显像评估99^Tc^m标记人源化抗人血小板膜糖蛋白（GP）Ⅲa单克隆抗体（简称单抗）F（ab）2片段SZ21F（ab）2的应用价值。方法通过体外抑制二磷酸腺苷（ADP）诱导的犬血小板聚集实验，评估SZ21F（ab）2与血小板结合的亲和性和特异性。以2-亚氨基噻吩盐酸盐（IT）法修饰SZ21F（ab）2分子的亚氨基，以99^Tc^m-葡庚糖酸钠（GH）转换络合法进行标记。分别用快速薄层层析（ITLC）法和ELISA测定标记物的放化纯及生物活性。对3条肺动脉血栓和8条（包括上述3条）后肢深静脉血栓栓塞比格犬模型进行显像研究。结果SZ21F（ab）2抑制ADP诱导的犬富含血小板血浆（PRP）聚集实验的半数有效剂量（IC50）为（2．49±1．88）μg／ml。ITLC法测得标记物的放化纯为90％～95％，ELISA测定结果表明标记后抗体保留了免疫活性。注射显像剂后1h，肺动脉血栓部位和后肢深静脉血栓部位均出现放射性浓聚。注射后3h，在体显像肺动脉血栓和后肢深静脉血栓栓塞模型的放射性靶／本底（T／B）比值分别为3．03±1．18和3．51±0.62。肺动脉血栓部位和后肢深静脉血栓部位的每克组织百分注射剂量率（％ID／g）分别为0．083％ID／g和0．076％ID／g。体外检测结果表明：肺动脉血栓与正常肺组织的单位质量放射性比值平均为12．8，后肢深静脉血栓与血液的单位质量放射性比值平均为5．2，与肌肉的比值平均为127.0。结论99^Tc^m-SZ21F（ab）2与人血小板具有较高的亲和力，有潜在的血栓显像应用前景。     

In vitro adsorption of 99Tc(m)-MIBI, 99Tc(m)-tetrofosmin, 99Tc(m)-furifosmin and 99Tc(m)O4- onto tubes

Adsorption of radiopharmaceuticals onto disposable syringes has been reported to amount to levels of almost 50%. Data on adsorption of radiopharmaceuticals onto materials used for in vitro studies are extremely limited. We assessed the extent of adsorption of 99Tc(m) hexakis(2-methoxyisobutylisonitrile) (99Tc(m)-MIBI), 99Tc(m)-tetrofosmin, 99Tc(m)-furifosmin and 99Tc(m)O4 onto tubes used for in vitro measurement of cellular uptake of these radiopharmaceuticals. The influence on adsorption of different incubation media, temperature and time of incubation was evaluated. Total (not corrected for adsorption) uptake was compared with corrected, net cellular uptake in SK-BR-3, MCF-7 and liposarcoma cell lines. Values of adsorption ranging from 0.94+/-0.13% to 7.07+/-0.46% were found. The extent of adsorption of all the radiopharmaceuticals varied with the type of incubation medium and the incubation temperature. With 99Tc(m)-furifosmin, adsorption was dependent on the incubation time as well on the incubation temperature and some of the incubation media investigated. Our findings indicate that systematic investigations to evaluate the adsorption of radiopharmaceuticals onto materials used during in vitro studies of cellular uptake should be considered a mandatory aspect of quality control.     

Preparation of 99mTc-ethylene dicysteine (99mTc-EC) by transchelation using 99mTc-glucoheptonate (99mTc-GHA) and its evaluation for renal function studies

The complexation of ethylene dicysteine (EC) with 99mTc needs to be carried out at pH 12 to achieve a high radiochemical yield. However, the preparation of the kit at high pH poses difficulties and requires very stringent preparation conditions, as stannous tin, one of the main ingredients in the kit, is unstable at high pH. Hence, an alternative method, involving the transchelation preparation of 99mTc-EC using 99mTc-glucoheptonate (99mTc-GHA) prepared at pH 6.5, was attempted, prompted by the reported success of the preparation of 99mTc-sestamibi (99mTc-MIBI) by this method. The preparation of 99mTc-EC by this method first involved the formation of 99mTc-GHA by the addition of sodium pertechnetate-99mTc to the Sn-GHA kit vial at pH 6.5. 99mTc-EC was formed by the addition of reconstituted EC solution at pH approximately 12 to the preformed 99mTc-GHA. The reaction was allowed to proceed both at room temperature and on a boiling water bath. The pH of the final product was adjusted to pH approximately 7 with 0.5 M phosphate buffer at pH 4-5, without affecting the quality of the product. The urinary excretion of 99mTc-EC prepared by transchelation, tested in mice, was similar to that of directly prepared 99mTc-EC, indicating that the final product prepared by the two methods was the same. The clinical evaluation of the product formulated by the new procedure showed satisfactory findings, comparable with the reports in the literature.     

Use of (99m)Tc from a commercial (99)Mo/(99m)Tc generator as yield tracer for the determination of (99)Tc at low levels.

The concentrations of (99)Tc and impurity radionuclides in the (99m)Tc tracer solution obtained from a commercial (99)Mo/(99m)Tc generator were measured by gamma spectrometry and liquid scintillation counting. (99)Mo and (103)Ru were found in the (99m)Tc eluate. A simple separation using two extra alumina cartridges was investigated to purify the eluate to obtain a suitable (99m)Tc tracer with low (99)Tc concentration. The activity ratio of (99)Tc/(99m)Tc in the prepared (99m)Tc solution is lower than 15 x 10(-9), which is higher than the theoretical ratio of less than 10 x 10(-9). The possible reason is discussed. The (99)Tc in the 20 kBq spiked (99m)Tc tracer was found to be less than 0.3 mBq, which is lower than the detection limit of the radiometric method used for environmental samples. The purified (99m)Tc eluate is used as yield tracer for the determination of low levels of (99)Tc in environmental samples.     

Alteration of the organ uptake of the (99m)Tc-radiopharmaceuticals, (99m)Tc-DPD, (99m)Tc-DMSA, (99m)Tc-tin colloid and (99m)Tc-MAA, induced by the applied cytotoxic drugs methotrexate sodium and cyclophosphamide

AIM: To investigate the influence of certain cytotoxic drugs on the organ uptake of the following (99m)Tc-radiopharmaceuticals: (99m)Tc-2,3-dicarboxypropane-1,1-diphosphonic acid ((99m)Tc-DPD), (99m)Tc-meso-2,3-dimercaptosuccinic acid ((99m)Tc-DMSA), (99m)Tc-tin colloid and (99m)Tc-macroaggregated albumin ((99m)Tc-MAA). Methotrexate sodium and cyclophosphamide were used as models to evaluate these effects. METHODS: Two groups of healthy male Wistar rats were treated separately by oral application of the drugs for 7 days. On the eighth day, each of the (99m)Tc-radiopharmaceuticals was applied in a separate group of treated animals. They were sacrificed at different time intervals and the radioactivity in the organs of interest was measured. The organ uptake of the (99m)Tc-radiopharmaceuticals in an additional control group of animals was also studied. RESULTS: The results obtained showed an alteration in the organ uptake of (99m)Tc-radiopharmaceuticals in animals treated with cytotoxic drugs. In rats treated with methotrexate sodium, there was a higher uptake of (99m)Tc-DMSA in the bones, stomach and intestine, a higher uptake of (99m)Tc-DPD in the bones, intestine, blood and muscle, a lower uptake of (99m)Tc-tin colloid in the liver and a lower accumulation of (99m)Tc-MAA in the lungs. Cyclophosphamide-treated animals showed enhanced uptake of (99m)Tc-DMSA in the kidneys, a twofold enhanced uptake of (99m)Tc-DPD in all organs except the stomach, a decreased uptake of (99m)Tc-tin colloid in the lungs, spleen and kidneys and a significantly decreased uptake of (99m)Tc-MAA in the lungs. CONCLUSION: These results confirm that both methotrexate sodium and cyclophosphamide may alter the organ uptake of (99m)Tc-radiopharmaceuticals in experimental animals.