Differentiated teaching modes of course of digital signal processing for undergraduates and postgraduates / 医疗卫生装备

Objective To analyze the difference of teaching modes of course of digital signal processing for the undergraduates and postgraduates.Methods The teaching modes were compared from the aspects of educational objective,teaching content, teaching method,examination mode and etc.Results Differentiated teaching modes contributed to the satisfactory education of the undergraduates and postgraduates. Conclusion The differentiated teaching modes for the undergraduates and postgraduates provide references for the high-level education in universities and colleges of science and technology. [Chinese Medical Equipment Journal,2018,39(5):87-89,102]

Accurately controlling resistivity of 3D printing materials for establishing human-head volume conductor model / 医疗卫生装备

Objective To propose a method for accurately controlling the resistivity of 3D printing materials to facilitate to establish a human-head volume conductor model.Methods Two kinds of ABS/CB composite conductive printing materials covering the resistivity ranges of parenchymal and skull were selected through resistivity measurement and analysis. The correlation between the proportions and resistivities of the two kinds of ABS/CB materials and the empirical formula on the correlation between the resistivity and proportion was obtained through exponential function fitting. Results The selected ABS/CB composite material behaved well in frequency stability and time stability,and the obtained empirical formula had high-correlation coefficient.Conclusion Accurate control of 3D printing model resistivity is realized,and it's facilitated to gain 3D printing material with the same resistivity as those of skull and parenchymal.

Novel human-head phantom with realistic skull anatomy and resistivity distribution / 医疗卫生装备

Objective To establish a human-head phantom with realistic skull anatomy and resistivity distribution in order to provide an accurate experimental platform for brain electrical impedance tomography(EIT).Methods Firstly a skull model with 3-layer structure was constructed with double-nozzle 3D printer,and every layer had its specific resistivity verified on the accuracy. Then brain parenchyma with its resistivity was modelled using 3D printer and cerebrospinal fluid and scalp were mimicked using NaCl solution;after the whole phantom was assembled,imaging test using EIT was performed.Results The skull model was similar to the realistic one in terms of anatomy and resistivity distribution;the EIT experiment on the new phantom showed similar results to simulation.Conclusion The proposed phantom has realistic skull anatomy,resistivity distribution and multi-layer anatomical structure, which reflects the features of skull resistivity and thus is suitable for experiments on brain EIT.

Evaluation by damped least-square algorithm on target identification ability of intracranial focal bidirectional electrical impedance perturbation / 医疗卫生装备

Objective To evaluate the effect of damped least-square algorithm on the identification of focal bidirectional electrical impedance perturbation in the intracranial area, and to analyze the influence of this kind of perturbation on the reconstruction quality of electrical impedance tomography. Methods Focal bidirectional electrical impedance perturbation was built based on the three-dimensional model and damped least-square algorithm was introduced into imaging. The position error and resolution were used to evaluate the imaging performance.Results When the focal electrical impedance perturbation existed,the target whose conductivity varied greatly or volume was large was more likely to be identified in the images while the target with smaller volume or variable conductivity presented in the reconstruction image was not obvious. It's pointed out that it may cause reconstruction images in some cases could not truly reflect the location and change information of the object of primary cerebral hemorrhage.At the same time,it affected the reconstruction precision,causing the position error and resolution with large fluctuation. Conclusion In reconstruction algorithm linearity correct matrix introduced for bidirectional electrical impedance perturbation contributes to enhancing the recognition of bidirectional perturbation, so that the characterization of the electrical impedance imaging can be augmented for clinical intracerebral hemorrhage.

Case-control study of therapeutic effects between extreme lateral interbody fusion and conventional posterior operation for the treatment of upper lumbar disc herniation / 中国骨伤

<p><b>OBJECTIVE</b>To evaluate the clinical outcomes between extreme lateral interbody fusion and conventional posterior operation in the treatment of upper lumbar disc herniation.</p><p><b>METHODS</b>Among 60 patients with upper lumbar disc herniation were treated with extreme lateral interbody fusion(XLIF) or conventional posterior operation from June 2010 to December 2014, 30 patients(19 males and 11 females) were treated with XLIF (XLIF group); and the other 30 patients(17 males and 13 females) were treated with conventional posterior operation (conventional group). In XLIF group, the lesions occurred at T₁₂L₁ segments in 2 patients, at L₁,₂ segments in 6 patients, at L₂,₃ segments in 10 patients, and at L₃,₄ segment in 12 patients. In conventional group, the lesions occurred at T₁₂L₁ segments in 1 patient, at L₁,₂ segments in 6 patients, at L₂,₃ segments in 8 patients, and at L₃,₄ segment in 15 patients. Operative incision lengths, time, blood loss, postoperative draining volume, hospital stays were recorded. Pre-and post-operative visual analogue score(VAS) and Japanese Orthopedic Association(JOA) were compared between two groups. According to the image data, the intervertebral fusion device was observed to be displaced and the rate of interbody fusion was analyzed.</p><p><b>RESULTS</b>All the patients were followed up, and the duration ranged from 12 to 48 months, with an average of 29 months. The complications included 2 femoral nerve damage in XLIF group (postoperative recovery within 3 months) and superficial incision infection in conventional group(cured by anti-infection). There were no patients with cerebrospinal fluid leakage(CSFL), cauda equina injuries or functional deterioration in the nerve root of lower limbs. In the XLIF group: the operative time was (65.6±20.5) minutes, blood loss was (48.8±15.3) ml, postoperative draining volume was 0 ml. In the conventional group: the operative time was (135.2±33.9) minutes, blood loss was (260.3±125.7) ml, postoperative draining volume was (207.1±50.2) ml. The operative time, blood loss, postoperative draining volume in XLIF group were less than those in the conventional group(<0.05). The JOA and VAS score were significantly improved in both groups during the follow-up period compared with those before operation(<0.05). But the difference of the JOA and VAS score between the two groups 1, 6, and 24 months after surgery had not significant differences(>0.05). There were no significant differences in the fusion rate between the two groups 6 and 12 months after operation(>0.05).</p><p><b>CONCLUSIONS</b>The XLIF fusion for the treatment of upper lumbar disc herniation has several advantages such as minimal invasive, stable vertebral plate, less complications and postoperative fusion rate, which has a better clinical effect.</p>