A contextual based double watermarking of PET images by patient ID and ECG signal

Abstract

Abstractc o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 1 0 4 ( 2 0 1 1 ) [418][419][420][421][422][423][424][425] j o u r n a l h o m e p a g e : w w w . i n t l . e l s e v i e r h e a l t h . c o m / j o u r n a l s / c m p b A contextual based double watermarking of PET images by patient ID and ECG signal a b s t r a c tThis paper presents a novel digital watermarking framework using electrocardiograph (ECG) and demographic text data as double watermarks. It protects patient medical information and prevents mismatching diagnostic information. The watermarks are embedded in selected texture regions of a PET image using multi-resolution wavelet decomposition.Experimental results show that modifications in these locations are visually imperceptible. The robustness of the watermarks is verified through measurement of peak signal to noise ratio (PSNR), cross-correlation (CC%), structural similarity measure (SSIM) and universal image quality index (UIQI). Their robustness is also computed using pixel-based metrics and human visual system metrics. Additionally, beta factor (ˇ) as an edge preservation measure is used for degradation evaluation of the image boundaries throughout the watermarked PET image. Assessment of the extracted watermarks shows watermarking robustness to common attacks such as embedded zero-tree wavelet (EZW) compression and median filtering.© 2010 Elsevier Ireland Ltd. All rights reserved. IntroductionThe huge amounts of acquired digital medical images in hospitals are usually stored in a database along with the demographic text data and the bio-signals of patients. Unauthorized tampering, mismatching and mishandling of information are problems with such data in large databases. Additionally, exchange of bio-signals, demographic texts and medical images between hospitals needs efficient and reliable transmission and storage techniques. Moreover, storing different information of a patient in separate files increases the risk of mismatching and diagnostic mistakes. Unauthorized * Corresponding author. viewing of patients' healthcare information is one of the main concerns in hospital information systems. Recently, watermarking has been an active area of research for strengthening healthcare information security. Generally, watermarking algorithms have been aimed to protect digital images by hiding information into them. The main advantage of watermarking is information invisibility and anonymity. Authentication is considered a genuine application for them. A large number of watermarking techniques for medical images are available in literature which almost most of them focus on two areas, namely, tamper detection and authentication, and electronic patient record (EPR) embedding in medical images. Significantly, embedding of EPR or metadata 0169-2607/$ -see front matter

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