基于差影技术的乳腺微钙化点检测方法

目的协助医生进行诊断,避免医生因大量阅片引起疲劳而造成误诊,提高乳腺癌早期诊断的效率和准确率。方法先对乳腺钼靶 X 线照片数字化；再对数字化的乳腺影像归一化；然后从中选取感兴趣区域；最后利用差影技术检测出微钙化点并标示于影像中。结果对于16幅(其中13幅含有微钙化)经过病理解剖确诊的乳腺钼靶片进行实验,利用本文方法共检测出14幅钙化图像。结论该方法检出率高。微钙化点定位准确,值得进一步研究。     

Using information on realized effects to determine prospective causal effects

The potential outcomes approach to causal inference postulates that each individual has a number of possibly latent outcomes, each of which would be observed under a different treatment. For any individual, some of these outcomes will be unobservable or counterfactual. Information about post-treatment characteristics sometimes allows statements about what would have happened if an individual or group with these characteristics had received a different treatment. These are statements about the realized effects of the treatment. Determining the likely effect of an intervention before making a decision involves inference about effects in populations defined only by characteristics observed before decisions about treatment are made. Information on realized effects can tighten bounds on these prospectively defined measures of the intervention effect. We derive formulae for the bounds and their sampling variances and illustrate these points with data from a hypothetical study of the efficacy of screening mammography.     

Stress and job satisfaction in mammography radiographers

Abstract

Previous research suggests that substantial numbers of health professionals experience undue levels of occupational stress. Little is yet known, however, about a recently established specialized group, namely radiographers who work in the UK National Health Service Breast Screening Programme. All 134 radiographers in the first wave of the programme were sent a postal questionnaire to determine how stressed they felt at work, how satisfied they were with the job, and what were the principal causes of stress and dissatisfaction. A total of 103 were returned, a response rate of 77 %. The results showed that 30 % reported high levels of stress, which is more than in most other professions, and that only 17% described themselves as ‘very satisfied’ with their jobs. The most important predictors of stress were problems of communication (mainly knowing what to tell the client) and conflicts between home and work. The most important predictor of dissatisfaction was role ambiguity. Ways of reducing stress and increasing satisfaction must be found if radiographers are to remain healthy and are to continue to work for the programme.     

Bayesian analysis of dynamic magnetic resonance breast images

Summary.  We describe an integrated methodology for analysing dynamic magnetic resonance images of the breast. The problems that motivate this methodology arise from a collaborative study with a tumour institute. The methods are developed within the Bayesian framework and comprise image restoration and classification steps. Two different approaches are proposed for the restoration. Bayesian inference is performed by means of Markov chain Monte Carlo algorithms. We make use of a Metropolis algorithm with a specially chosen proposal distribution that performs better than more commonly used proposals. The classification step is based on a few attribute images yielded by the restoration step that describe the essential features of the contrast agent variation over time. Procedures for hyperparameter estimation are provided, so making our method automatic. The results show the potential of the methodology to extract useful information from acquired dynamic magnetic resonance imaging data about tumour morphology and internal pathophysiological features.     

Stress and job satisfaction in mammography radiographers

Previous research suggests that substantial numbers of health professionals experience undue levels of occupational stress. Little is yet known, however, about a recently established specialized group, namely radiographers who work in the UK National Health Service Breast Screening Programme. All 134 radiographers in the first wave of the programme were sent a postal questionnaire to determine how stressed they felt at work, how satisfied they were with the job, and what were the principal causes of stress and dissatisfaction. A total of 103 were returned, a response rate of 77 %. The results showed that 30 % reported high levels of stress, which is more than in most other professions, and that only 17% described themselves as 'very satisfied' with their jobs. The most important predictors of stress were problems of communication (mainly knowing what to tell the client) and conflicts between home and work. The most important predictor of dissatisfaction was role ambiguity. Ways of reducing stress and increasing satisfaction must be found if radiographers are to remain healthy and are to continue to work for the programme.     

A review of cancer screening evaluation techniques, with some particular examples in breast cancer screening

Summary.  The instigation of mass screening for breast cancer has, over the last three decades, raised various statistical issues and led to the development of new statistical approaches. Initially, the design of screening trials was the main focus of research but, as the evidence in favour of population-based screening programmes mounts, a variety of other applications have also been identified. These include administrative and quality control tasks, for monitoring routine screening services, as well as epidemiological modelling of incidence and mortality. We review the commonly used methods of cancer screening evaluation, highlight some current issues in breast screening and, using examples from randomized trials and established screening programmes, illustrate the role that statistical science has played in the development of clinical research in this field.