Evidence-based cross validation for acoustic power transmission for a novel treatment system

Introduction: The novel Trans-Fusimo Treatment System (TTS) is designed to control Magnetic Resonance guided Focused Ultrasound (MRgFUS) therapy to ablate liver tumours under respiratory motion. It is crucial to deliver the acoustic power within tolerance limits for effective liver tumour treatment via MRgFUS. Before application in a clinical setting, evidence of reproducibility and reliability is a must for safe practice.

Materials and methods: The TTS software delivers the acoustic power via ExAblate-2100 Conformal Bone System (CBS) transducer. A built-in quality assurance application was developed to measure the force values, using a novel protocol to measure the efficiency for the electrical power values of 100 and 150W for 6s of sonication. This procedure was repeated 30 times by two independent users against the clinically approved ExAblate-2100 CBS for cross-validation.

Results: Both systems proved to deliver the power within the accepted efficiency levels (70–90%). Two sample t-tests were used to assess the differences in force values between the ExAblate-2100 CBS and the TTS (p?>?0.05). Bland-Altman plots were used to demonstrate the limits of agreement between the two systems falling within the 10% limits of agreement. Two sample t-tests indicated that TTS does not have user dependency (p?>?0.05).

Conclusions: The TTS software proved to deliver the acoustic power without exceeding the safety levels. Results provide evidence as a part of ISO13485 regulations for CE marking purposes. The developed methodology could be utilised as a part of quality assurance system in clinical settings; when the TTS is used in clinical practice.     

关于实验结果置信度的探讨

本文以常用的百分率为例,通过理论分析和实际计算表明:从实验样本数N不同的条件下得到的实验结论的可信性是存在着显著差异的。由此指出对实验结论进行置信度分析的重要性和必要性,并建议从生物医学的特点出发,建立一个适当的置信度要求标准。这将为增强科学性,提高效率,降低成本发挥效益。     

A structural equation modelling approach to the analysis of change

Analysis of change is probably the most commonly adopted study design in medical and dental research when comparing the efficacy of two or more treatment modalities. The most commonly used methods for testing the difference in treatment efficacy are the two-sample t -test and the analysis of covariance ( ancova ). It has been suggested that ancova should be used in the analysis of change for data from randomized controlled trials (RCTs) as a result of its greater statistical power. However, it is less well known that although both methods will give rise to similar results in the analysis of change for RCTs, there are different assumptions behind these methods in terms of the relationship between baseline value and the subsequent change, and the results may therefore differ if baseline values are not balanced between groups. This article uses structural equation modelling as a conceptual framework to explain the assumptions behind these methods, and two examples are used to show when the two methods yield similar results and why, in some non-randomized studies, the two methods might give substantially different results, known as 'Lord's paradox' in the statistical literature. For the appropriate interpretation of non-randomized studies, the assumptions underlying these methods therefore need to be taken into consideration.     

西林瓶装注射用水的装量检查分析

为了检查西林瓶装注射用水的实际分装量是否符合2005年版《药典》三部要求,按照2005年版《药典》三部中“生物制品分装和冻干规程”,分装规格为0．8ml的西林瓶装注射用水10000瓶,随机在分装过程的前、中、后阶段共抽取100瓶,轧盖、目检。分别用1ml标定注射器及1ml普通无菌注射器抽取每瓶注射用水的实际体积,以t检验法对实际抽取量与标示量的差值进行统计学分析,结果显示其与2005年版《药典》三部要求分装附加量为0．1ml相比有显著性差异（P〈0．001）。     

A simple method of sample size calculation for unequal-sample-size designs that use the logrank or t-test

This paper presents a simple method of calculating sample sizes for unequal-sample-size designs with use of published tables applicable to equal-sample-size design. The method applies to both the logrank test and the t-test. For the power of logrank test, this paper compares the proposed method with existing methods and with the Monte Carlo simulation.     

ISSUES IN BIOMEDICAL STATISTICS: COMPARING MEANS UNDER NORMAL DISTRIBUTION THEORY

The test used most commonly in biomedical research to compare means when measurements have been made on a continuous scale is Student's t-test, followed closely by various forms of analysis of variance. These tests require that defined populations have been randomly sampled, but there are other assumptions about populations and samples that must be satisfied. These include: (i) normality of the population distributions; (ii) equal variance in those normal populations; and (iii) statistical independence of the samples. This review offers advice to investigators on how to recognize breaches of the assumptions of normality and equality of variance, and how to deal with them by modifying the usual t-test or by transforming the experimental data. The sample-size also has an important bearing on statistical inferences: (i) if it is too small. the risk of Type II error is inflated; and (ii) inequality of sample size exaggerates the effects of inequality of variance. The assumption of independence is breached if repeated measurements are made serially rather than in random order, but adjustments to analysis of variance can be made to correct for the inflated risk of Type I error. The review also considers the problem of making multiple comparisons of means. and recommends solutions.     

基于Excel上的医疗物资管理系统的构建

科技发展和社会进步对医疗卫生提出更高的要求,同样对医疗卫生物资管理提出了更高的要求。本文阐叙了基于Excel上的医疗物资管理系统的构建原理和方法。该系统的构建,有助于医疗物资管理部门对医疗物资的微观分析和医院管理者的宏观决策。     

Effects of Forming Parameters on Fatigue Life in Incremental Sheet Punching

In order to investigate the effects of main forming parameters on the fatigue life in incremental sheet punching, wavelength and amplitude were selected as factors, and fatigue life of truncated pyramids and virgin material was selected as indicator. The effects of the parameters were identified whereby the design of full factorial experiment, fatigue comparative test, analysis of variance, Tukey test, and t-test. It was found that wavelength and amplitude significantly affect the fatigue life. In addition, the improvement of fatigue life decreased with the increment of wavelength and increased with the increment of amplitude when it is less than a certain value, followed by decreasing.     

HPLC-CAD法同时测定氨糖美辛肠溶片中两种成分的含量

目的:对于现行标准中氨糖美辛肠溶片含量测定步骤繁琐，氨基柱柱效下降快等问题，建立一种高效液相色谱-电喷雾检测器(HPLC-CAD)同时测定两种主成分的方法。方法:色谱柱：Waters XBridge-C₁₈(4.6 mm×250 mm, 5μm),流动相A为0.1%冰醋酸溶液，流动相B为乙腈，采用梯度洗脱的方式，流速为0.7 mL·min^-1,柱温：30℃,进样量：20μL,检测器为CAD(雾化温度：45℃;数据采集频率：10 Hz;滤光片：10.0 s)。结果:供试品溶液中两主峰达到基线分离，阴性溶液中辅料峰与主峰无干扰。吲哚美辛和盐酸氨基葡萄糖线性范围分别为0.0125～0.25 mg·mL^-1和0.037 5～0.75 mg·mL^-1,加样回收率分别为100.00%～102.21%、98.74%～101.90%,统计学t检验结果显示该方法与药典标准方法的测定结果无显著差异。结论:该方法具有操作简便，灵敏度高，专属性强，可作为氨糖美辛肠溶片的含量测定替代方法。