Explored the Function of Electromagnetic Compatibility (EMC) of Medical Devices from the Perspective of Test / 中国医疗器械杂志

OBJECTIVE@#To improve the electromagnetic compatibility (EMC) quality of medical devices, improve the efficiency of EMC testing, and promote the speed of market approval.@*METHODS@#The unqualified cases of EMC test items of medical devices in recent years were statistically analyzed, and the reasons of low EMC quality of medical devices were analyzed from the perspective of test.@*RESULTS@#Based on the analysis of the reasons, the suggestions were given from the perspectives of medical device manufacturers and testing organizations.@*CONCLUSIONS@#In order to ensure the quality of EMC of medical devices, medical device manufacturers, regulatory authorities and inspection and testing institutions should strengthen the monitoring and evaluation of medical device electromagnetic compatibility, to ensure the safety of products work together to promote the development of the medical device industry healthily and orderly.

Bionic optic nerve based on perovskite (CsPbBr 3) quantum-dots / 生物医学工程学杂志

The bionic optic nerve can mimic human visual physiology and is a future treatment for visual disorders. Photosynaptic devices could respond to light stimuli and mimic normal optic nerve function. By modifying (Poly(3,4-ethylenedioxythio-phene):poly (styrenesulfonate)) active layers with all-inorganic perovskite quantum dots, with an aqueous solution as the dielectric layer in this paper, we developed a photosynaptic device based on an organic electrochemical transistor (OECT). The optical switching response time of OECT was 3.7 s. To improve the optical response of the device, a 365 nm, 300 mW·cm -2 UV light source was used. Basic synaptic behaviors such as postsynaptic currents (0.225 mA) at a light pulse duration of 4 s and double pulse facilitation at a light pulse duration of 1 s and pulse interval of 1 s were simulated. By changing the way light stimulates, for example, by adjusting the intensity of the light pulses from 180 to 540 mW·cm -2, the duration from 1 to 20 s, and the number of light pulses from 1 to 20, the postsynaptic currents were increased by 0.350 mA, 0.420 mA, and 0.466 mA, respectively. As such, we realized the effective shift from short-term synaptic plasticity (100 s recovery of initial value) to long-term synaptic plasticity (84.3% of 250 s decay maximum). This optical synapse has a high potential for simulating the human optic nerve.

Finite element analysis of the effect of local posterior sclera collagen cross-linking on eyeball shape / 生物医学工程学杂志

China is the country with high incidence of high myopia in the world. High myopia can cause severe vision impairment. So far, there is no effective treatment for high myopia in clinic. Scleral collagen cross-linking surgery has been proven to be effective in preventing animal eye axial elongation

The effect of parasitic ions on riboflavin permeability and cross-linking effectiveness in iontophoresis-assisted scleral cross-linking / 生物医学工程学杂志

The effect of parasitic ions on the results of ultraviolet A (UVA) cross-linking in iontophoresis was still not clear. In this work, the porcine sclera was cross-linked by riboflavin lactate Ringer's solution (group A) and riboflavin normal saline (group B)

Phantom study in the quality control of low dose solid pulmonary nodule CT based on radiomics analysis / 中华放射学杂志

Objective:To investigate the value of radiomics in image quality control with low-dose CT examination of solid pulmonary nodules.Methods:Images were acquired on CT750 HD scanner, and chest pulmonary nodules phantom were scanned at different tube voltage and tube current. The radiation dose CTDI vol under different scanning conditions were recorded, as well as CNR and SNR of each scanning sequence. The variation of radiation dose, noise, tube voltage and tube current were analyzed. All data were analyzed by radiomics analysis software. R language statistics software was adopted to analyze the extracted features by principal component analysis (PCA), and the characteristic parameters with the largest contribution rate to image quality were selected for analysis. One-way ANOVA was used to analyze all the important characteristic parameters to reveal the difference of characteristic parameters under different tube voltages. Finally, the post-test method was used to find out the differences among different tube voltage groups. Results:Radiation dose rised linearly with the increase of tube current and tube voltage. Although the overall change trend of SNR and CNR in pulmonary nodules was linearly related to the change of tube voltage and tube current, there was no clear change trend threshold at low dose, which could not accurately evaluate the image quality under low radiation. Both CNR and SNR cannot evaluate the image quality effectively, and have no practiced value for optimizing the low dose scanning parameters. There main components including Uniformity, Voxel Value Sum, and Haralick Correlation extracted by radiomics analysis software were proved to play a critical role in image quality control. The cumulative contribution rate of variance was 89.20% and the eigen values were greater than 1. Uniformity curve of characteristic parameter showed that the trend of change was correlated with the change of tube voltage and tube current, and the stability and consistency were good. Uniformity one-way ANOVA analysis showed that when the tube voltage reduced from 140 to 120 kVp, there was no difference ( P=0.117) in the uniformity, while from 120 to 80 kVp, significant differences revealed ( P<0.001). Considering tube current, no significant variation was observed in uniformity when current was greater than 90 mA, which indicated that tube current of 90 mA could lead to better image quality. Conclusion:Radiomics analysis can effectively evaluate and control the CT image quality of low dose solid pulmonary nodules.

Numerical Simulation for the Safe Retention Value of Residual Stromal Bed Thickness in Laser-Assisted in situ Keratomileusis / 医用生物力学

Objective To study the effects of different residual stromal bed thickness (RSBT) in laser-assisted in situ keratomileusis (LASIK) surgery on geometric deformation and stress changes of the cornea under different intraocular pressures (IOP), and evaluate safety of the three retention values (250, 280, 300 μm). Methods The models of normal cornea and corneas with different RSBT after surgery were established by the finite element software ABAQUS. Appropriate loading and boundary conditions were set and then the corresponding displacement and stress were calculated. Results The apical displacement of the postoperative cornea (RSBT=250 μm) under IOP=2.66 kPa was basically the same as that of the normal cornea (RSBT=550 μm) under IOP=5.32 kPa. RSBT=280 μm was in the low risk area of keratoconus, while RSBT=250 μm was in the high-risk area. At a value between 280 μm and 300 μm of RSBT, the stress distribution was nearly consistent with that of the normal cornea. With RSBT=300 μm, the stromal layer of the cornea lost 40% of the strongest strength against tissue tension. Conclusions RSBT=250 μm is the minimum retention value for LASIK surgery. RSBT=250 μm is the high risk value. With RSBT=330-340 μm, LASIK surgery is safe enough for most patients.

Regional Mechanical Properties of the Sclera / 医用生物力学

Objective To investigate the differences in mechanical properties of the sclera in different regions. Methods The sclera of sus scrofa was divided into 3 regions, namely, anterior, equatorial and posterior area. Local indentation was performed on different areas of the whole sclera. Strip specimens of different regions were circumcised along the equatorial direction, and subjected to uniaxial stretching by INSTRON 5544. Results Within the normal physiological stress range, the stiffness at anterior, equatorial, and posterior area of the sclera measured by local indentation was (0.91±0.21), (0.6±0.16), (0.39±0.13) MPa, respectively. The elastic modulus at anterior, equatorial, and posterior area of the sclera measured by uniaxial stretching was (1-28±0.37), (0.95±0.31), (0.72±0.28) MPa, respectively. Conclusions The local indentation could reflect regional mechanical properties of the sclera. The anterior sclera performed a higher stiffness than the equatorial and posterior areas. The results provide references for further study on the pathogenesis of ocular diseases including myopia.

Phantom study in the quality control of low dose solid pulmonary nodule CT based on radiomics analysis / 中华放射学杂志

Objective@#To investigate the value of radiomics in image quality control with low-dose CT examination of solid pulmonary nodules.@*Methods@#Images were acquired on CT750 HD scanner, and chest pulmonary nodules phantom were scanned at different tube voltage and tube current. The radiation dose CTDIvol under different scanning conditions were recorded, as well as CNR and SNR of each scanning sequence. The variation of radiation dose, noise, tube voltage and tube current were analyzed. All data were analyzed by radiomics analysis software. R language statistics software was adopted to analyze the extracted features by principal component analysis (PCA), and the characteristic parameters with the largest contribution rate to image quality were selected for analysis. One-way ANOVA was used to analyze all the important characteristic parameters to reveal the difference of characteristic parameters under different tube voltages. Finally, the post-test method was used to find out the differences among different tube voltage groups.@*Results@#Radiation dose rised linearly with the increase of tube current and tube voltage. Although the overall change trend of SNR and CNR in pulmonary nodules was linearly related to the change of tube voltage and tube current, there was no clear change trend threshold at low dose, which could not accurately evaluate the image quality under low radiation. Both CNR and SNR cannot evaluate the image quality effectively, and have no practiced value for optimizing the low dose scanning parameters. There main components including Uniformity, Voxel Value Sum, and Haralick Correlation extracted by radiomics analysis software were proved to play a critical role in image quality control. The cumulative contribution rate of variance was 89.20% and the eigen values were greater than 1. Uniformity curve of characteristic parameter showed that the trend of change was correlated with the change of tube voltage and tube current, and the stability and consistency were good. Uniformity one-way ANOVA analysis showed that when the tube voltage reduced from 140 to 120 kVp, there was no difference (P=0.117) in the uniformity, while from 120 to 80 kVp, significant differences revealed (P<0.001). Considering tube current, no significant variation was observed in uniformity when current was greater than 90 mA, which indicated that tube current of 90 mA could lead to better image quality.@*Conclusion@#Radiomics analysis can effectively evaluate and control the CT image quality of low dose solid pulmonary nodules.

Experimental study on mechanical properties of the ventral and the dorsal tissues of porcine descending aorta / 生物医学工程学杂志

The mechanical properties of the aorta tissue is not only important for maintaining the cardiovascular health, but also is closely related to the development of cardiovascular diseases. There are obvious differences between the ventral and dorsal tissues of the descending aorta. However, the cause of the difference is still unclear. In this study, a biaxial tensile approach was used to determine the parameters of porcine descending aorta by analyzing the stress-strain curves. The strain energy functions Gasser-Ogden-Holzapfel was adopted to characterize the orthotropic parameters of mechanical properties. Elastic Van Gieson (EVG) and Sirius red stain were used to observe the microarchitecture of elastic and collagen fibers, respectively. Our results showed that the tissue of descending aorta had more orthotropic and higher elastic modulus in the dorsal region compared to the ventral region in the circumferential direction. No significant difference was found in hyperelastic constitutive parameters between the dorsal and ventral regions, but the angle of collagen fiber was smaller than 0.785 rad (45°) in both dorsal and ventral regions. The arrangement of fiber was inclined to be circumferential. EVG and Sirius red stain showed that in outer-middle membrane of the descending aorta, the density of elastic fibrous layer of the ventral region was higher than that of the dorsal region; the amount of collagen fibers in dorsal region was more than that of the ventral region. The results suggested that the difference of mechanical properties between the dorsal and ventral tissues in the descending aorta was related to the microstructure of the outer membrane of the aorta. In the relatively small strain range, the difference in mechanical properties between the ventral and dorsal tissues of the descending aorta can be ignored; when the strain is higher, it needs to be treated differently. The results of this study provide data for the etiology of arterial disease (such as arterial dissection) and the design of artificial blood vessel.

Hyperelastic analysis for the passive behavior of fox extraocular muscles in vitro / 医用生物力学

Objective To determine the hyperelastic parameters of shear modulus (μ) and curvature parameter (α) of extraocular muscles (EOMs) in Ogden hyperelastic model,so as to provide theoretical basis for clinical EOM surgery by numerical modeling.Methods The passive behavior of fox EOMs in vitro was determined by the uniaxial tensile test,and the hyperelastic analysis was conducted using the first-order Ogden model and ABAQUS software.Results The experimental result showed that the passive behavior of fox EOMs was nonlinear.The corresponding hyperelastic parameters μ =(6.57 ± 3.76) kPa and oα =8.16 ± 1.63 were obtained.When the strain of EOMs was larger than 6％,there were no statistical differences between the experimental result and the calculation result of the first-order Ogden hyperelastic model (P ＞ 0.05).Both the calculation result and the simulation result well fitted to the experimental result.Conclusions The hyperelastic parameters identified in this study can be used as the input for the corresponding numerical modeling of fox EOMs.

The influence of low concentration iodinated contrast agent and low-dose CT scanning technique combined with body mass index on radiation dose and image quality of upper abdominal CT examinations / 中华放射学杂志

Objective To investigate the influence of“double low”technology(low concentration iodinated contrast agent and low-dose scan) combined with body mass index(BMI) on radiation dose and image quality of contrast-enhanced upper abdominal CT examination. Methods One hundred and twenty patients who received upper abdominal enhanced CT examination were randomly divided into 4 groups:group A1, the iodinated contrast agent iodixanol(270 mg/ml), BMI0.05). There was no significant difference in contrast noise ratio of liver parenchyma(P>0.05), while significant differences existed in CT values of abdominal aorta and liver parenchyma, contrast noise ratio of abdominal aorta between group A1 and B1(P<0.05). Significant differences existed in the parameters above mentioned between group A2 and B2, respectively(P<0.05). Radiation dose was lower in group A1 than in group B1 and in group A2 than in group B2(P<0.05), respectively. Radiation dose was decreased by 40.1%(0.89/2.22) in group A1 than group B1 while radiation dose decreased by 56.9%(3.02/5.31) in group A2 than group B2. Conclusion According to BMI, the low concentration iodinated contrast agent and low-dose scan CT scanning technology could effectively reduce radiation dose and generate ideal images during the contrast-enhanced upper abdominal CT examination.

The performance of the microbial barrier of needleless positive pressure closed connectors / 中国医疗器械杂志

<p><b>OBJECTIVE</b>Analyzing the performance of microbial barrier of needleless positive pressure closed connectors.</p><p><b>METHODS</b>Three kinds of brand needleless positive pressure closed connectors were chosen to do the access of microorganisms test.</p><p><b>RESULTS</b>Positive results were detected in the three experimental groups.</p><p><b>CONCLUSIONS</b>So far, lots of the connectors are not qualified strictly on the market, some improvement is required in the structure design and process.</p>