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Objective To investigate the factors affecting the dose distribution to the tumor target volume(GTV)and normal tissues in cerebral arteriovenous malformation(AVM)treated with CyberKnife,and to analyze the effect of collimators of different diameters on the dose distribution of cerebral AVM,so as to provide references for cerebral AVM CyberKnife treatment plans.Methods Totally 12 cerebral AVM patients receiving CyberKnife treatment after embolization in some hospital between 2015 and 2020 were selected.Collimators were determined according to 30％,40％,50％,30％+40％+50％of the GTV cross-sectional long diameters,and four different treatment plans were developed for each patient and then enrolled into Group A,Group B,Group C,and Group D,respectively.The effects of the shape and volume of GTV and the size of collimator on the dose distribution in the target area were analyzed,and the dose fall-off outside the target area was investigated.SPSS 20.0 software was used for statistical analysis.Results The effects of width,height,volume and regularity of GTV on the conformity index(CI),new conformity index(nCI),geometric conformity index(gCI)and number of beams were statistically significant(P＜0.05).When compared with group A,B and D,group C had the minimum dose,median absorbed dose,target area coverage,target gradient index and prescription dose line of GTV increased while the CI,nCI,gCI of GTV and the number of monitor units,treatment nodes and beams decreased significantly(P＜0.05).In group C median absorbed dose of normal tissue more than 20 mm apart from the target area decreased,while median absorbed dose of normal tissue not longer than 15 mm apart from the target area increased.Conclusion During CyberKnife treatment of cerebral AVMs,collimator selection based on 50％of the GTV cross-sectional long diameter can achieve an optimal dose distribution while improving the efficiency of the execution of the CyberKnife treatment plan.[Chinese Medical Equipment Journal,2023,44(11):56-60]
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A new derivative of ordered mesoporous carbon (GSH-CMK-3) has been prepared by chemical modification and functionalization of ordered mesoporous carbon with glutathione. The composite was fully characterized by means of Fourier transforming infrared spectroscopy (FT-IR), scanning electron microscope (SEM) image and thermogravimetric analysis (TGA). GSH-CMK-3 showed favorable chemical stability, thermal stability and excellent adsorption performance toward Cd2+and a maximum adsorption capacity of 87.87 mg/g was achieved. The adsorption kinetic follows pseudo-second-order adsorption model. In a sequential injection mini-column separation system, 0. 006 mol/L sulfourea (in 0. 2 mol/L HNO3) was adopted as eluent and the elution efficiency was 96%. With a sample volume of 1000 μL and 50 μL of eluate, an enrichment factor of 17.3 was obtained. A procedure for on-line selective separation and preconcentration of trace Cd2+was developed by graphite furnace atomic absorption spectrometry. Along with a detection limit of 1.9 ng/L (n=7,3σ) and a linear range of 0.05-0.20 μg/L, a RSD of 2.9% (n=13,100 ng/L) was achieved. The method was validated by analyzing Cd2+in a certified reference material GBW08608.