Lossless watermarking for verifying the integrity of medical images with tamper localization.

Given the ease of alteration of digital data, integrity verification and tamper detection for medical images are becoming ever more important. In this paper, instead of using the conventional irreversible block-based watermarking approach to achieve tamper localization, we propose to incorporate such functionality into the region-based lossless watermarking scheme. This is achieved by partitioning an image into certain non-overlapping regions and appending the associated local authentication information directly into the watermark payload. A region of authentication, which can be flexibly specified by the user, is partitioned into small regions in a multilevel hierarchical manner. Such hierarchical structure allows the user to easily adjust the localization accuracy, and makes the tamper detection efficient. Experimental results demonstrate the effectiveness of tamper localization.

A region-based lossless watermarking scheme for enhancing security of medical data.

This paper presents a lossless watermarking scheme in the sense that the original image can be exactly recovered from the watermarked one, with the purpose of verifying the integrity and authenticity of medical images. In addition, the scheme has the capability of not introducing any embedding-induced distortion in the region of interest (ROI) of a medical image. Difference expansion of adjacent pixel values is employed to embed several bits. A region of embedding, which is represented by a polygon, is chosen intentionally to prevent introducing embedding distortion in the ROI. Only the vertex information of a polygon is transmitted to the decoder for reconstructing the embedding region, which improves the embedding capacity considerably. The digital signature of the whole image is embedded for verifying the integrity of the image. An identifier presented in electronic patient record (EPR) is embedded for verifying the authenticity by simultaneously processing the watermarked image and the EPR. Combining with fingerprint system, patient's fingerprint information is embedded into several image slices and then extracted for verifying the authenticity.

A grid-based model for integration of distributed medical databases.

Grid has emerged recently as an integration infrastructure for sharing and coordinated use of diverse resources in dynamic, distributed environment. In this paper, we present a prototype system for integration of heterogeneous medical databases based on Grid technology, which can provide a uniform access interface and efficient query mechanism to different medical databases. After presenting the architecture of the prototype system that employs corresponding Grid services and middleware technologies, we make an analysis on its basic functional components including OGSA-DAI, metadata model, transaction management, and query processing in detail, which cooperate with each other to enable uniform accessing and seamless integration of the underlying heterogeneous medical databases. Then, we test effectiveness and performance of the system through a query instance, analyze the experiment result, and make a discussion on some issues relating to practical medical applications. Although the prototype system has been carried out and tested in a simulated hospital information environment at present, the underlying principles are applicable to practical applications.

[Approaching molecular imaging].

In this paper the concept of molecular imaging is introduced, and its importance is addressed. Besides, the key points of molecular imaging are briefly reviewed from a view of engineering. Particular emphasis is given to the analysis of the function and the position of traditional medical imaging modalities in the era of molecular imaging. Finally a discussion is made for the further development of medical imaging modalities along the line of molecular imaging.

[Identity recognition based on local registration of chest radiography].

In a PACS system, doctors can avoid the mistakes in filing chest radiographs by comparing the new image with the old ones from the same patient. An automatic method with digital image processing technology is introduced in the paper, which is realized by general location of anatomical structures, local image registration and BP artificial neural network, so as to achieve good results for identity recognition.

[Preliminary study on force feedback of acupuncture in virtual reality based on the visible human].

This paper discusses the application of virtual reality technology in the 3-D visible human body and acupuncture research. Based on the 3-D visible human fused with the localization information and hierarchy of acupoints, the paper analyzes the force against the needle and haptic rendering during the needle manipulation according to the physical properties of different tissues. A haptic model is constructed to demonstrate the force behaviors during acupuncture, and the force will be produced and passed to the manipulator by a force feedback device. It enriches the contents of 3-D visible human project, provides a dynamic simulation instrument for acupuncture teaching, and supplies a platform for acupuncture research.

[Development of DICOM software platfrom for medical image communication].

In this paper, we have brought forward the framework design of DICOM software platform, using the SUR-DICOM-Lib software and have completed the connection test with the RSNA-CTNT Test Node. PACS, DICOM, realize

[The study of associated reconstruction using MV linear accelerator and cone-beam CT].

In this paper, we proposed a new scan mode and image reconstruction method, which combines the data from both the linear accelerator and the cone-beam CT to reconstruct the volume with a limited rotation angle and low sampling rate. The classical filtered backprojection method and the iterative method are utilized to reconstruct the volume. The reconstruction results of the two methods are compared with each other with a relavant anlysis given here.

[Research on testing the robustness of DICOM-e-mail secure teleradiology systems].

DICOM-e-mail is a secure teleradiology protocol released by German Radiology Society and has already been applied clinically. To improve the robustness of the system, the protocol has been upgraded by adding some mechanisms such as system feedback. Moreover, a test method is also implemented by sending erroneous mails to application software that supports DICOM-e-mail. Through the tests for two different DICOM-e-mail teleradiology application, the validity of the new protocol is proved and at the same time some bugs are found. The implementation of the latest protocol and the general error tests can help to make the whole teleradiology system a better robustness. The implementation of DICOM-e-mail protocol in our country is also discussed in this paper.

[Research on the distributed PACS based on grid technology].

In this paper, we introduce the grid technology into the design of the distributed PACS. First, we analyse the architecture and functions of OGSA-DAI, and then, introduce a model of the distributed PACS based on OGSA-DAI, and give a detailed analysis on its basic components and workflow. Finally, we make a conclusion on the distributed PACS based on grid technology.

[Preliminary assessment of osteoporosis in vivo MR image analysis].

This paper presents a non-invasive and non-ionizing radiation method for assessment of osteoporosis by analyzing in vivo MR images. Texture features (entropy, coarse, etc...) derived from co-occurrence matrix and neighborhood graystone difference matrix are obtained. These features are significantly different between patients and control subjects. Then the grayscale MR image is transformed to the binary image, The shape and topology features (area, skeleton length, euler number, etc. ) obtained from the binary image show too significant differences between patients and control subjects.

Lymph node segmentation from CT images using fast marching method.

Accurate lymph node size analysis is important medically. This paper presents an improved fast marching method to perform semi-automatic segmentation for lymph node from CT images. In this work, we have incorporated the gray scale information of the target region into the fast marching speed term and have given a hard constraint for the stop criteria, instead of only using the spatial image gradient, to remedy the 'boundary leaking' problem of the traditional fast marching method. Various experimental results are provided to demonstrate the effectiveness of the proposed method.

[Discussion of naive Bayesian algorithm in prognosis prediction of primary liver cancer].

OBJECTIVE: To apply naive Bayesian algorithm in prognosis prediction of primary liver cancer and to predict the survival expectation of patients after transcatheter arterial chemoembolization (TACE). METHOD: Naive Bayesian algorithm was applied. Using correlation analysis to sift data-attributes. Whereas the missing data were assumed to follow the same distribution as that of the known. RESULT: The same-distribution assumption of the missing data reduces the error rate from 71.9% to 9.4%. Twelve attributes were sifted from 39 attributes by the correlation analysis, which were more effective to the final classification, and had a relatively low error rate of 3.1%. CONCLUSION: The proposed method effectively increases the accuracy of classification. Successful application of the naive Bayesian algorithm in prognostic problem of primary liver cancer indicates a bright future of this method in medical field.

[PACS evolution in China between 1990-2000 and its prospect].

In this paper a brief history of the development of PACS in China is reviewed, the current status of PACS is presented, and its development in the future is discussed.

[Quantitative analysis on pulmonary radiological images].

This paper presents a review of the quantitative analysis on pulmonary radiological images, including chest films and CT scans.

[A 3D-rendering system for medical images based on COM].

This paper introduces a 3D medical image rendering system. The system uses the technology of COM with a fine upgradable and maintainable performances. Its main functions include image filtering, enhancement, image classification & segmentation, image registration, image interpolation and 3D display. The system can run on PC, so it owns a good practical value.

[CT/MRI-based software for 3-D brachytherapy planning system].

The paper presents a 3D Brachytherapy Planning System based on CT/MRI images. Unlike other percutaneous radiotherapy planning systems, it provides doctors with an interactive source layout function, including accurate and quick dosage distribution calculation and dynamical 2D/3D display. A special template library and an integrated planning evaluation/alert subsystem are incorporated in the system. The system successfully has many functions such as data acquisition, registration, segmentation, image processing, 3D reconstruction and planning report output. Various automated procedures, 3-D graphics and a user-friendly interface GUI enable the system to be a powerful and practical one meeting well the chinical therapeutic demands.

[The research on accuracy of computer-assisted surgery].

The computer-assisted surgery system is a complex system. All of the errors can be attributed to the loss of correspondence between the world coordinate system in the operation room and the virtual world coordinate system obtained from the multi-model medical images. The system's accuracy is composed of the accuracy of the localizer and that of registration. In order to improve the system accuracy, we analyse most of the possible error sources. The accuracy of the localizer affects deeply the registration between the intra-operation and pre-operation data. The localizer is the most basic and important part for a computer-assisted surgery system. We give a comprehensive possible error source at the end of the paper.

[Study on the angle and depth of needle insertion at Huantiao (GB 30) by three-dimensional reconstruction].

OBJECTIVE: To observe the anatomic structure of Huantiao (GB 30) visually, to imitate the inserting process of the needle to explore the safty of needle insertion and improve the therapeutic effect of acupuncture in clinic. METHODS: Combined with anatomic structure of acupoint, muscles and other tissues related with Huantiao (GB 30) were interactively segmented in VOXEL-MAN with the computer graphics technology. Nerves and blood vessels were reconstructed by establishing mathematic model, and the needle-inserting animation of Huantiso (GB 30) was obtained by running script file. RESULTS: The three-dimensional (3-D) visualization of Huantiao (GB 30) on needle-inserting animation was accomplished, the spatial location and expression of Huantiao (GB 30) in the digitized virtual human body were observed, the virtual inserting process was imitated realistically, and the 3-D animation of needle insertion at Huantiao (GB 30) was created. CONCLUSION: Building mathematic model is favorable for expressing the anatomic structure of Huantiao (GB 30) in 3-D space, imitating the process of needle insertion realistically and observing the spatial structure of the point and the around tissues, which can provide a solid foundation for the safety of needle insertion of acupoints and improve therapeutic effect of acupuncture in clinic.

[Study on force feedback of acupuncture manipulation at Jianliao (TE 14) based on VOXEL-MAN].

OBJECTIVE: To discuss the mechanical virtual reality when acupuncture on Jianliao (TE 14) so as to get perform perceptual knowledge of acupuncture for beginners through studying 3D reconstruction of surrounding tissues of this acupoint. METHODS: Related tissues were segmented and reconstructed by establishing mathematics model based on the operational platform of VOXEL-MAN (vision reappearance); and mechanical model was constructed and fused with related data of virtual human (touch reappearance); data communication between the force feedback apparatus and the operational platform of virtual human were set up by interchanging vision reappearance module and touch reappearance module. RESULTS: In Linux system, the operator could experience the mechanical changes while needle-tip passing various tissues of Jianliao (TE 14) as well as lifting and thrusting evenly in needling process through the force feedback apparatus. CONCLUSION: Based on the platform of VOXEL-MAN, the sensation of needling at jianliao (TE 14) could be reappeared idealy by strength feedback instrument, so that the beginners could imitate, learn and practice the virtual acupuncture.