Lossless Set Compression of Correlated Information.

Set compression allows the compression a set of similar (correlated) images more efficiently than compressing the same images independently. Currently, set compression is performed with different inter-image predictive models, that forecast the common image properties from a few reference images. With sufficient inter-image correlation, one can predict any database image from a few templates, hence avoiding inter-image redundancy and achieving much improved compression ratios. This research focused on two major aspects of this technique: the practical limits of the predictive set compression, and the theoretical estimates of the compression efficiency. This includes a review of the previous work in set compression area, a discussion of the more important statistical and informational aspects involved in predictive set compression, practical observations and measurements for medical (CT and MR) data, and theoretical analysis of lossless similar image compression. This research proposes new and more reliable approaches for lossless set compression, as well as their extensions to more general lossy set compression

Implementation of an anonymisation tool for clinical trials using a clinical trial processor integrated with an existing trial patient data information system

To present an adapted Clinical Trial Processor (CTP) test set-up for receiving, anonymising and saving Digital Imaging and Communications in Medicine (DICOM) data using external input from the original database of an existing clinical study information system to guide the anonymisation process. Two methods are presented for an adapted CTP test set-up. In the first method, images are pushed from the Picture Archiving and Communication System (PACS) using the DICOM protocol through a local network. In the second method, images are transferred through the internet using the HTTPS protocol. In total 25,000 images from 50 patients were moved from the PACS, anonymised and stored within roughly 2 h using the first method. In the second method, an average of 10 images per minute were transferred and processed over a residential connection. In both methods, no duplicated images were stored when previous images were retransferred. The anonymised images are stored in appropriate directories. The CTP can transfer and process DICOM images correctly in a very easy set-up providing a fast, secure and stable environment. The adapted CTP allows easy integration into an environment in which patient data are already included in an existing information system. Store DICOM images correctly in a very easy set-up in a fast, secure and stable environment Allows adaptation of the software to perform a certain task based on specific needs Allows easy integration into an existing environment Reduce the possibility of inappropriate anonymisation

An Open Source Toolkit for Medical Imaging De-Identification

Objective: Medical imaging acquired for clinical purposes can have several legitimate secondary uses in research projects and teaching libraries. No commonly accepted solution for anonymising these images exists because the amount of personal data that should be preserved varies case by case. Our objective is to provide a flexible mechanism for anonymising DICOM data that meets the requirements for deployment in multicentre trials. Methods: We reviewed our current de-identification practices and defined the relevant use cases to extract the requirements for the de-identification process. We then used these requirements in the design and implementation of the toolkit. Finally, we tested the toolkit taking as a reference those requirements, including a multicentre deployment. Results: The toolkit sucesfully anonymised DICOM data from various sources. Furthermore, it was shown that it could forward anonymous data to remote destinations, remove burned-in annotations, and add tracking information to the header. The toolkit also implements the DICOM standard confidentiality mechanism. Conclusion: A DICOM de-identification toolkit that facilitates the enforcement of privacy policies was developed. It is highly extensible and provides the necessary flexibility to account for different de-identification requirements, but at the same time, it has a low adoption barrier to new users

Temporal Extension of the Select Statement – New Clauses

Effective timed data processing belongs to one of the most important tasks in the development of current information and database systems. It is not, however, only the changes in time management, but also the complex record of changes during the whole life cycle of the object – historical values, actual states, but also data valid in the future. Existing temporal solutions are inadequate in terms of performance - effectiveness of the whole system, which is manifested by the size of the required data and processing time. There is no temporal solution for Select statement defined and the user has to manage it explicitly. This paper deals with the principles of temporal data modeling on the object and attribute level. It also describes the characteristics of Select statement used in the temporal system, extends it with new characteristics and defines new layer for transformation into existing syntax

Assessment of perceptual distortion boundary through applying reversible watermarking to brain MR images

The digital medical workflow faces many circumstances in which the images can be manipulated during viewing, extracting and exchanging. Reversible and imperceptible watermarking approaches have the potential to enhance trust within the medical imaging pipeline through ensuring the authenticity and integrity of the images to confirm that the changes can be detected and tracked. This study concentrates on the imperceptibility issue. Unlike reversibility, for which an objective assessment can be easily made, imperceptibility is a factor of human cognition that needs to be evaluated within the human context. By defining a perceptual boundary of detecting the modification, this study enables the formation of objective guidelines for the method of data encoding and level of image/pixel modification that translates to a specific watermark magnitude. This study implements a relative Visual Grading Analysis (VGA) evaluation of 117 brain MR images (8 original and 109 watermarked), modified by varying techniques and magnitude of image/pixel modification to determine where this perceptual boundary exists and relate the point at which change becomes noticeable to the objective measures of the image fidelity evaluation. The outcomes of the visual assessment were linked to the images Peak Signal to Noise Ratio (PSNR) values, thereby identifying the visual degradation threshold. The results suggest that, for watermarking applications, if a watermark is applied to the 512x512 pixel (16 bpp grayscale) images used in the study, a subsequent assessment of PSNR=82dB or greater would mean that there would be no reason to suspect that the watermark would be visually detectable. Keywords: Medical imaging; DICOM; Reversible Watermarking; Imperceptibility; Image Quality; Visual Grading Analysis

Digital watermarking : applicability for developing trust in medical imaging workflows state of the art review

Medical images can be intentionally or unintentionally manipulated both within the secure medical system environment and outside, as images are viewed, extracted and transmitted. Many organisations have invested heavily in Picture Archiving and Communication Systems (PACS), which are intended to facilitate data security. However, it is common for images, and records, to be extracted from these for a wide range of accepted practices, such as external second opinion, transmission to another care provider, patient data request, etc. Therefore, confirming trust within medical imaging workflows has become essential. Digital watermarking has been recognised as a promising approach for ensuring the authenticity and integrity of medical images. Authenticity refers to the ability to identify the information origin and prove that the data relates to the right patient. Integrity means the capacity to ensure that the information has not been altered without authorisation. This paper presents a survey of medical images watermarking and offers an evident scene for concerned researchers by analysing the robustness and limitations of various existing approaches. This includes studying the security levels of medical images within PACS system, clarifying the requirements of medical images watermarking and defining the purposes of watermarking approaches when applied to medical images

Analysis of the Dynamics of Heat Exchange at Different Power of the Unit Continuous Combined Casting and Pressing Aluminum Alloy

Приведены результаты численного исследования непрерывного совмещенного литья и прессования опытного алюминиевого сплава АК12 при различной производительности установки с горизонтальным карусельным кристаллизатором. Дана количественная оценка влияния темпа разогрева кристаллизатора на температурно-временные характеристики в период переходного теплового процесса. Определены теплотехнические зоны, характеризующиеся различной интенсивностью теплообмена между расплавом и стенками кристаллизатора. Показано, что увеличение производительности установки сокращает продолжительность переходного теплового процесса при пуске установки из холодного состояния до достижения ею стационарного теплового режима. Получена зависимость времени выхода установки на стационарный тепловой режим от скорости вращения колеса-кристаллизатораA numerical study of the process of continuous combined casting and pressing of experimental aluminum alloy AK12 at various capacities of the continuous combined casting and pressing semi-industrial unit was carried out. A quantitative assessment of the influence of the heating rate of the crystallizer on the temperature and time characteristics during the transition thermal process is given. The heat engineering zones characterized by different intensity of heat exchange between the melt and the walls of the crystallizer are determined. It is shown that increasing the semi-industrial unit performance reduces the duration of the transient thermal process when starting from a cold state until it reaches a stationary thermal mode. The dependence of the time when the unit reaches a stationary thermal mode on the rotation speed of the horizontal crystallizer is obtaine