Adaptive noise correction of dual-energy computed tomography images.

PURPOSE: Noise reduction in material density images is a necessary preprocessing step for the correct interpretation of dual-energy computed tomography (DECT) images. In this paper we describe a new method based on a local adaptive processing to reduce noise in DECT images METHODS: An adaptive neighborhood Wiener (ANW) filter was implemented and customized to use local characteristics of material density images. The ANW filter employs a three-level wavelet approach, combined with the application of an anisotropic diffusion filter. Material density images and virtual monochromatic images are noise corrected with two resulting noise maps. RESULTS: The algorithm was applied and quantitatively evaluated in a set of 36 images. From that set of images, three are shown here, and nine more are shown in the online supplementary material. Processed images had higher signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than the raw material density images. The average improvements in SNR and CNR for the material density images were 56.5 and 54.75%, respectively. CONCLUSION: We developed a new DECT noise reduction algorithm. We demonstrate throughout a series of quantitative analyses that the algorithm improves the quality of material density images and virtual monochromatic images.

An algorithm for noise correction of dual-energy computed tomography material density images.

PURPOSE: Dual-energy computed tomography (DECT) images can undergo a two-material decomposition process which results in two images containing material density information. Material density images obtained by that process result in images with increased pixel noise. Noise reduction in those images is desirable in order to improve image quality. METHODS: A noise reduction algorithm for material density images was developed and tested. A three-level wavelet approach combined with the application of an anisotropic diffusion filter was used. During each level, the resulting noise maps are further processed, until the original resolution is reached and the final noise maps obtained. Our method works in image space and, therefore, can be applied to any type of material density images obtained from any DECT vendor. A quantitative evaluation of the noise-reduced images using the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and 2D noise power spectrum was done to quantify the improvements. RESULTS: The noise reduction algorithm was applied to a set of images resulting in images with higher SNR and CNR than the raw density images obtained by the decomposition process. The average improvement in terms of SNR gain was about 49 % while CNR gain was about 52 %. The difference between the raw and filtered regions of interest mean values was far from reaching statistical significance (minimum [Formula: see text], average [Formula: see text]). CONCLUSION: We have demonstrated through a series of quantitative analyses that our novel noise reduction algorithm improves the image quality of DECT material density images.

Recording and reenactment of collaborative diagnosis sessions using DICOM.

This paper presents a radiological collaborative tool capable of direct manipulation of Digital Imaging and Communications in Medicine (DICOM) images on both sides, and also recording and reenacting of a recorded session. A special collaborative application protocol formerly developed was extended and used as basis for the development of collaborative session recording and playback processes. The protocol is used today for real-time radiological meetings through the Internet. This new standard for collaborative sessions makes possible other uses for the protocol, such as asynchronous collaborative sessions, decision regulation, auditing, and educational applications. Experimental results are given which compare this protocol with other popular collaborative approaches. Comparison of these results shows that the proposed protocol performs much better than other approaches when run under controlled conditions.

Certificação digital de exames em telerradiologia: um alerta necessário / Digital certification in teleradiology: a necessary warning

A crescente popularização das atividades de telemedicina em todo o mundo tem exigido de médicos e demais profissionais da saúde novas abordagens em sua prática profissional. No que se refere à telerradiologia, observamos forte tendência à transformação de documentos clínicos - como resultados de exames, que até hoje existiam na forma de filmes impressos e laudos em papel - em documentos eletrônicos, disponibilizados em redes internas de clínicas e hospitais, ou pela internet. Esta tendência torna necessária a divulgação e o esclarecimento de conceitos como a certificação digital, a criptografia de dados na internet, a confiabilidade de sites, o documento eletrônico confiável e a assinatura digital. Os princípios básicos desses conceitos, embora por vezes complexos para os profissionais da saúde, podem ser compreendidos de forma efetiva sem que o leitor tenha de mergulhar de cabeça em labirintos como a matemática da criptografia de chaves assimétricas ou os protocolos de comunicação digital de dados. Neste artigo abordaremos de forma direta e com exemplos práticos os aspectos de segurança e confiabilidade de documentos clínicos eletrônicos baseados na internet, com o objetivo de que os usuários médicos possam interagir de forma informada, segura e bem fundamentada com serviços de telerradiologia.

The increasing worldwide popularization of telemedicine activities has demanded a new approach to the professional practice by physicians and other health professionals. As far as teleradiology is concerned, a remarkable trend has been observed toward the transformation of clinical documents - like radiological studies results, that so far existed as printed films and paper-based reports - into electronic documents available in internal networks of medical clinics and hospitals or through the internet. As a result of this trend, it is necessary to divulge and explain concepts such as digital certification, internet data encryption, sites' reliability, reliability of electronic documents, and digital signature. Even though the baseline principles of these concepts may seem complex for health professionals, they can be effectively understood with no need to wander through labyrinths like the mathematics of asymmetric keys cryptography, or digital data communication protocols. Security and reliability aspects related to internet-based electronic clinical documents are described in the present study, in a straight and practical way, aiming at an informed, safe and soundly grounded interaction between medical users and telemedicine services.