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PubMed2005

Diagnostic process from the data quality point of view.

The spread of electronic use of data in various areas has put importance of data quality to higher level. Data quality has syntactic and semantic component; the syntactic component is relatively easy to achieve if supported by tools (either off-the-shelf or our own), while semantic component requires more research. In many cases such data come from different sources, are distributed across enterprise and are at different quality levels. Special attention needs to be paid to data upon which critical decisions are met, such as medical data for example. The starting point for research is in our case the risk of the medical area. In the paper we will focus on the semantic component of medical data quality.

Computer Security↗
PubMed2004

Locally optimum nonlinearities for DCT watermark detection.

The issue of copyright protection of digital multimedia data has attracted a lot of attention during the last decade. An efficient copyright protection method that has been gaining popularity is watermarking, i.e., the embedding of a signature in a digital document that can be detected only by its rightful owner. Watermarks are usually blindly detected using correlating structures, which would be optimal in the case of Gaussian data. However, in the case of DCT-domain image watermarking, the data is more heavy-tailed and the correlator is clearly suboptimal. Nonlinear receivers have been shown to be particularly well suited for the detection of weak signals in heavy-tailed noise, as they are locally optimal. This motivates the use of the Gaussian-tailed zero-memory nonlinearity, as well as the locally optimal Cauchy nonlinearity for the detection of watermarks in DCT transformed images. We analyze the performance of these schemes theoretically and compare it to that of the traditionally used Gaussian correlator, but also to the recently proposed generalized Gaussian detector, which outperforms the correlator. The theoretical analysis and the actual performance of these systems is assessed through experiments, which verify the theoretical analysis and also justify the use of nonlinear structures for watermark detection. The performance of the correlator and the nonlinear detectors in the presence of quantization is also analyzed, using results from dither theory, and also verified experimentally.

Algorithms↗
PubMed1995

Authentication of digital medical images with digital signature technology.

PURPOSE: To determine whether digital signature technology (DST) can authenticate digital medical images to the same level of authenticity required for interbank electronic transfer of funds. MATERIALS AND METHODS: Message digests were computed for two magnetic resonance images that differed only by the value of a single bit. RSA (Rivest, Shamir, and Adleman) public key cryptography was used to encrypt each message digest to form a digital signature for each image, a process analogous to the established use of RSA DST for electronic funds transfer. The process was then reversed to authenticate the original image from its digital signature. RESULTS: Although the images differed by less than 0.000095%, their message digests differed at 94% of their characters. The digital signature of the original image proved that it was authentic and that the altered image was not authentic. CONCLUSION: RSA DST can establish the authenticity of images to at least the level of confidence required for interbank electronic transfer of funds.

Algorithms↗
PubMedDate not supplied

Computerized assessment of depression and anxiety over the telephone using interactive voice response.

We examined the reliability and validity of computer-administered versions of the Hamilton Depression (HAMD) and Hamilton Anxiety (HAMA) Rating Scales that were administered over the telephone using Interactive Voice Response (IVR). In two identical studies (HAMD: N = 113, HAMA: N = 74), both the IVR- and clinician-administered versions were administered in a counterbalanced order to a heterogeneous sample of subjects with psychiatric disorders and controls. Both the IVR HAMD and HAMA demonstrated adequate internal-consistency reliability (.90 and .93, respectively) and test-retest reliability (.74 and .97, respectively). The correlation between the IVR and clinician was high (HAMD = .96; HAMA = .65). The mean score difference between the IVR and clinician versions was less than one point for both the HAMD (.69 of a point) and HAMA (.60 of a point). It took subjects 12.23 minutes to complete the IVR HAMD, compared to 15.21 minutes for the clinician version; and 11.27 minutes for the IVR HAMA, compared to 15.33 minutes for the clinician (p < .001 for both comparisons). Subjects rated the clinician better in the areas of how much they liked being interviewed and how well they were able to describe their feelings. However, they were significantly more embarrassed with the clinician than with the IVR. Results support the psychometric properties of the IVR versions of the HAMD and HAMA scales. IVR technology presents new opportunities for expanding the utility of computerized clinical assessment.

Adult↗