How to suppress noise is necessary to consider the question of focus in hardware design.The external noise can be avoided or reduced by the way of reasonable design.The variety of influencing factors on power supply noise of the operational amplifier circuits are analyzed in more details and put forward corresponding solutions,in order to more fully exert low-noise op amp performance.

On the basis of generally stereotactic radiotherapy technology,intensity modulated radiation therapy technology has been developed greatly since 1990's.This technology is to improve the radiation dose distribution in the target so that the high dose area is more conformal for the three-dimentional shape of the target and the radiation dose in the normal organs and tissue around the target decreases.The characteristic of this new technology is discussed systematically in this paper.

In this paper, the mobile stereotactic radiosurgical system, a new therapeutant for interstitial radiotherapy, is introduced. Its principle and initial clinical applications are also summarized

Objective To evaluate the efficacy and safety of endoscopic balloon dilatation for patients with achalasia. Methods Patients with achalasia, were treated by single or double esophageal balloon dilatation under endoscopy,f ollowed up survey by gastroduodenal endoscopy and esophageal barium radiography as well as their symptoms were investigated periodically. Results The dysphagia symptoms remitted in all of the 43 patients,and mucosal lacerations,abrasions a nd oozing of blood, were found in this process but without complication of perf oration,haematemesis and melena.The following up ranged from 3 months to over 4. 8 yrs,and average was 2.6 yrs.The rate of remission of dysphagia symptoms 90.7 ％ (39/43) at six months,85.3％ (29/34) at 1 yr,82.6％ (19/23) at 2 yrs and 82.4 ％ (14/17) at 3 yrs,and the rate of recurrence of symptoms was 9.3％ (4/43)、 1 4.7％ (5/34)、 17.4％ (4/23)、 17.6％ (3/17),respectively.In addition,there were 37.2％ (16 cases)of patients with acid－ reflux symptoms,30.2％ (13 cases)heart burn and 14.0％ (6 cases)reflux esophagitis during the followed－ up. Conclusion Endoscopic esophageal balloon dilatation for achalasia is an effective and saf e method not only in the short－ term but also in the long－ term.

Since the body is a good conductor,the pacing signals and cardio-signals can be acquired together by ECG measuring circuit. The high pacing signals interfere with the processing of cardio-signal. This paper introduces a new method for restraining pacing signals and compares it with the traditional one based on slew inhibition. The result indicates that the new method is superior to the traditional one.

Music electrotherapy is a fusion of music therapy and electrotherapy,as a new digital medical technique,it has been concerned by medical workers.In this paper,a portable music therapeutic apparatus based on ARM-WINCE was developed.This apparatus could offer electrical stimulation,audio signal and visual signal provided by LCD.The core of system was ARM9 processor S3C2440,and using Windows CE as GUI development tool.The therapeutic apparatus has been developed and passed the detection.It has the features of small size,high reliability,low cost,and strong alternating capability,which is optimum in the fields of home health care and clinical research.

Objective To find a method for calculating the scatter dose of irregular fields. Methods The original Day function was improved to vary with radiation depth, and the improved Day function was used for irregular fields to calculate scatter dose. Results The accuracy was greatly improved by making Day function depend on radiation depth, and the error was within 1.5%. Conclusion This method can be used to calculate the scatter dose of irregular fields as well as rectangular fields.

Generally,pencil beam kernels for photon beam calculation are obtained through Monte Carlo calculations.In this paper,a pencil beam model is set up with a method of deconvolution from measured broad beam profiles.These profiles are usually available in a radiotherapy planning system.Furthermore,this method is applied to computing dose distributions at different sizes.Comparisons with measurements show that the accuracy of the calculated dose distributions fits well in a1%error interval in high dose gradient regions.

Objective To study the diagnostic value of endoscopic ultrasonography (EUS)for benign and malignant bile duct stricture.Methods Data of 51 patients who underwent EUS from January 2007 to March 2015 due to distal biliary stricture were retrospectively studied.And their diagnosis with EUS,IDUS,bile duct cytological brushing and final diagnosis were compared.Results Malignant bile duct stenosis were finally confirmed in 19 cases and benign stenosis were confirmed in 32 cases.The sensitivity (73.7％ VS 57.1％) and positive predictive value (73.7％ VS 57.1％) of EUS for the benign and malignant diagnosis of biliary tract stenosis were significantly higher than that of IDUS (P＜0.05),while their specificity(84.4％ VS 84.2％)and accuracy(80.4％ VS 76.9％)were similar.The sensitivity of EUS was significantly higher than that of bile duct cytological brushing (73.7％ VS 50.0％),while their specificity (84.4％ VS 100.0％)and accuracy(80.4％ VS 81.6％)were similar.EUS findings of hypoechoic mass features had higher diagnostic accuracy for detecting malignant distal bile duct stricture than irregular thickening of the lumen in the distal bile duct (100.0％ VS 64.3％,P＜0.05).Conclusion For patients with lesions of the distal bile duct that CT/MRI could not diagnose,EUS has an important value for the further diagnosis of benign and malignant bile duct stricture.

With the constant change of medical electronic instruments ( MEI ) professionals' needs,the professional personnel training programs need to be adjusted and improved.Based on the analysis of the MEI professional students'employment situation,this article discusses several key issues of the personnel training program,and puts forward some suggestions of improving the MEI professional's personnel training program,in combination with the actual running in the training,the training objective,course arrangement,practice teaching etc..