Health Level 7 Discuss HL7 medical standard. Health Level Seven (HL7) protocol for data exchange between computer systems in health care environments. HL7 defines messages for exchanging and procedures used for exchanging them. The '7' in HL7 refers to application layer (Layer 7) of OSI/ISO layer model. HL7 provides framework and related standards for the exchange, integration, sharing, and retrieval of electronic health information. HL7 was accredited in 1994 by the ANSI. HL7 focuses on clinical and administrative data domains. HL7 contains message standards that includes: o Patient administration o Entries for clinical service & observation, pharmacy, nutrition & supply order o Patient accounting and charges o Observation reporting o Document management services o Appointment scheduling o Laboratory automation o Personnel management
HL7 Messages HL7 messages are made up of segments. Some are: o MSH–Message Header that contains information about a message o EVN–Event Type that contains event information o PID–Patient Identification contains information about a patient o NK1–Next of Kin contains information about patient's related parties o OBR–Observation Request contains information about an order o OBX–Observation Report contains information about a result The HL7 message types for communicating HIS and diagnostic systems are: o ACK–General acknowledgement message o ORM–General order message www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.2
o ORR–General order response message o ORU–Unsolicited Transmission of observation The protocols used in HL7 implementation are: o Lower Layer Protocol (LLP) which is TCP/IP based o Simple Object Access Protocol (SOAP) which is XML based o Batch files are messages in text files exchanged by FTP and SMTP HL7 uses two encoding schemes: o HL7 ER known as traditional HL7 format used for HL7 version 2.x o XML is primary encoding scheme for HL7 v 3.0 HL7 is not plug and play. When deploying system utilizing HL7 interface, it must be adapted to hospital-specific requirements. HL7 tools assist developers in areas like: o Parsing and converting messages o Validating messages in accordance with HL7 standard and user-defined rules o Simulating HL7 message sender for diagnostic purposes o Networking features required for HL7
HL7 version 2.x The 2.x version supports clinical practice and management, delivery, and evaluation of health services and is most commonly used in the world. HL7 v2.x messages use a human-readable (ASCII), non-XML encoding syntax based on segments (lines) and one-character delimiters. Segments have fields separated by delimiter such as | ^ & and ~. An admission record is shown below: MSH|^~\&|MegaReg|XYZHospC|SuperOE|XYZImgCtr||P|2.5 EVN||200605290901||||200605290900 PID|||56782445^^^UAReg^PI||SAMPLE^BARRY ^JR||0105I30001^^99DEF^AN OBX|1|NM|^Body Height||1.80|m^Meter^ISO+|||||F OBX|2|NM|^Body Weight||79|kg^Kilogram^ISO+|||||F AL1|1||^ASPIRIN … DG1|1||786.50^CHEST PAIN, UNSPECIFIED^I9|||A
v2.x messaging standards is supported by all major vendors. Allows interoperability between electronic Patient Administration Systems (PAS), Electronic Practice Management (EPM) systems, Laboratory Information Systems (LIS), Dietary, Pharmacy and Billing systems as well as Electronic Medical Record (EMR) or Electronic Health Record (EHR) systems. HL7 version 3 HL7 version 3 is based on formal methodology and object-oriented principles. The Reference Information Model (RIM) is an essential part of the HL7 V3 development methodology. o RIM expresses the data needed in a specific clinical or administrative context. o RIM is essential to increase precision and reduce implementation costs. o Includes class and state-machine diagrams and references data type models. The HL7 Development Framework (HDF) seeks to develop specifications that facilitate interoperability between healthcare systems. o HDF not only documents messaging, but also the processes, tools, actors, rules, and artifacts relevant to development of all HL7 standard specifications. The messaging standard defines a series of messages called interactions to support all healthcare workflows. It is based on an XML encoding. www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.3
|^~\&LABfoo767543ADT19900314130405 ...
HL7 Standards Hospitals and other healthcare provider organizations typically have many different computer systems used for everything from billing records to patient tracking. HL7 specifies a number of flexible standards, guidelines, and methodologies by which various healthcare systems can communicate, share and process information in a consistent manner with each other. The Clinical Document Architecture (CDA) is an XML-based markup standard intended to specify the encoding, structure and semantics of clinical documents for exchange between healthcare providers and patients. o A CDA can contain any type of clinical content such as Discharge Summary, Imaging Report, Admission & Physical, Pathology Report, etc. o Supports the re-use of clinical data for public health reporting, quality monitoring, patient safety and clinical trials The Arden Syntax for Medical Logic Modules (MLMs) is used for encoding medical knowledge and representing and sharing that knowledge among personnel, information systems and institutions. o The MLMs assists physicians in decisions and alerts based on logic encoded into health knowledge bases. o Allows for distributed clinical rules development among institutions o Allows for improved dissemination of clinical knowledge HL7 messaging is transported by Minimal Lower Layer Protocol (MLLP) or LLP. o The purpose of the MLLP Protocol is to provide both a minimalistic session layer framing and reliable transport protocol. o For transmitting via TCP/IP, header and trailer characters are added to the message to identify the beginning and ending of the message. The Clinical Context Object Workgroup (CCOW) is a standard protocol designed to enable disparate applications to share user context and patient context in real-time. Electronic Health Record (EHR) / Personal Health Record (PHR) – in support of these records, a standardized description of health and medical functions sought for The Structured Product Labeling (SPL) specification is a document markup standard that specifies the structure and semantics of the content of authorized published information that accompanies any medicine licensed. o An SPL document is required by law to submit product information that includes original manufacturers, repackagers, relabelers, and agencies. o Enhances patient safety by helping to provide prescribers and consumers with improved access to information. Claims Attachments is a Standard Healthcare Attachment to augment another healthcare transaction GELLO/Rules is a standard expression language used for clinical decision support. www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.4
DICOM Standard Explain DICOM standard in detail. In early 1980s it was impossible for anyone other than manufacturers of CT or MRI devices to decode images that the machines generated. DICOM is a standard directed at addressing technical interoperability issues in medical imaging. It is not a framework/architecture for achieving clinical workflow. DICOM (Digital Imaging and Communications in Medicine) is a standard for handling, storing, printing, and transmitting information in medical imaging. It includes a file format definition and a network communications protocol that uses TCP/IP to communicate between systems. Developed by the National Electrical Manufacturers Association (NEMA) in conjunction with the American College of Radiology (ACR). DICOM files can be exchanged between two entities that are capable of receiving image/patient data in DICOM format. DICOM enables the integration of scanners, servers, workstations, printers, and network hardware from multiple manufacturers into a Picture Archiving and Communication System (PACS). DICOM has been widely adopted by hospitals and is making inroads in smaller applications like dentists' and doctors' offices. DICOM uses three different Data Element encoding schemes. DICOM Objects Things such as images, reports, and patients are all objects known as information objects. DICOM groups information into data sets, i.e., a file of a chest X-Ray image, for example, contains patient ID within the file, so that the image can never be separated from this information by mistake. A DICOM data object consists of a number of attributes, including items such as name, ID, etc., and also one special attribute containing the image pixel data. Objects are classified as Composite and Normalized objects. All objects and their formats constitute the data dictionary Uses UIDs to identify information objects, such as the images, reports, or transfer syntaxes. 1.2.840.10008 is the root for every DICOM UID DICOM Services Store is used to send images or other persistent objects (structured reports, etc.) to a PACS or workstation. Storage Commitment is used to confirm that an image was permanently stored by a device. Query/Retrieve enables a workstation to find lists of images or other such objects and then retrieve them from a PACS. Modality Worklist enables a piece of imaging equipment (a modality) to obtain details of patients and scheduled examinations electronically. Modality Performed Procedure Step enables the modality to send a report about a performed examination including data about the images acquired, beginning time, end time, and duration of a study, dose delivered, etc. Printing service is used to send images to a DICOM Printer, normally to print an "XRay" film. There is a standard calibration to help ensure consistency between various display devices, including hard copy printout.
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Vijai Anand
CS2361–Internet & Java
5.5
Off-line Media files describe how to store medical imaging information on removable media. DICOM files typically have a .dcm file extension.
The Service classes for Composite object are Verification, Storage, Query/Retrieve and Study Content Notification. Similarly service classes for Normalized object are Patient, Study, Results and Basic Print Management. Complex services are built using service elements, called DICOM message service elements (DIMSE). DIMSEs are classified as DIMSE-C and DIMSE-N The operations for DIMSE-C services are C-Store, C-Get, C-Move, C-Find, C-Echo. The operation for DIMSE-N services are N-Get, N-Set, N-Action, N-Create, N-Delete The service classes and information objects are combined to form SOP. Everything that DICOM does is based on the use of SOP classes. DICOM communication involves the exchange of SOP instances with use of DICOM messages. DICOM File format A DICOM file contains header that stores information about patient name, scan type, image dimensions, etc. Image data is stored in compressed or uncompressed form. The file header contains 128-byte preamble. Information Model DICOM information model includes relationships between the DICOM objects. DICOM information objects are definitions of the information to be exchanged. Each image type has specific characteristics. For example, a CT image requires different descriptors in the image header than an ultrasound image or an ophthalmology image. Information objects are part of the Service Object Pairs (SOP) Classes. An example is the CT Storage SOP Class, which allows CT images to be exchanged. Transport The DICOM protocol is rather robust. Each DICOM command is acknowledged. A device just does not send an object; it always negotiates whether the receiver indeed understands this type of service as well as the object type. This negotiation is referred to as Association establishment. In addition it also negotiates the Transfer syntax. The Transfer syntax is about the encoding that is used to exchange the information. A device might support the standard transfer syntax or a specific JPEG compression syntax that allows the information to be exchanged in a faster way. There are strict guidelines requiring each DICOM compatible device to describe its functionality, including supported SOP Classes and Transfer syntaxes in a document www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.6
called DICOM Conformance Statement. This document allows a user to determine in advance whether or not a specific device is compatible with other devices.
Dimensions The first level is the mechanism to exchange objects, such as images and diagnostic reports provided by the Storage SOP Classes. As soon as images are exchanged, users found that they require a PACS system administrator. The DICOM Modality Work List allows scheduling information to be retrieved by a modality. The other service is DICOM Storage Commitment, which transfers responsibility for the images to the receiver, so they can be safely removed from the local disk. To achieve consistency in the image presentation, the DICOM Grayscale Standard Display function specifies exactly what luminance or density level should be produced for a certain input value, based on the Barten curve. When a physician zooms an image, ads annotation, changes the window width and level, etc., the information is preserved using the DICOM Presentation State Service. In Structured Reporting, the message body is a Structured Report (SR). The advantage of a structure is that it lends itself very well to data mining. A critical part of the SR is the definition of templates that can easily be mapped to XML. The access control and authorization rules are taken care of by the application level software using passwords or biometric access controls. There is an audit and logging mechanism required that logs any data access and by whom. When accessed information is retrieved using a non-secure line, such as the Internet, the data can just be encrypted using standard mechanisms and utilities. The well-known port number for DICOM is 104.
www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.7
List the disadvantage of DICOM DICOM defines all the attributes that should be included in each modality which may be optional or required. A major disadvantage of DICOM standard is the possibility of entering too many optional fields which results in inconsistency and incorrect information. Some image objects are often incomplete because some fields are left blank and some are filled with incorrect data. List the goals of DICOM. Addresses the semantics of Commands and associated data. Addresses the semantics of file services, file formats and information directories necessary for off-line communication Is explicit in defining the conformance requirements of implementations of the standard. Facilitates operation in a networked environment Is structured to accommodate the introduction of new services, thus facilitating support for future medical imaging applications. Makes use of existing international standards wherever applicable. What is DICOM conformance statement? A Conformance Statement consists of: o Set of Information Objects which is recognized by this implementation o Set of Service Classes which this implementation supports o Set of communications protocols or media which this implementation supports o Set of security measures which this implementation supports List the features of DICOM. Incorporates negotiation to permit peers to agree on the functions to be performed. Defines 24 data types Message encoding includes JPEG compression (17 variants) Includes a robust UID mechanism and based on completely specified object data model Data dictionary includes large number of new data elements Defines classes of service for specific applications and conformance levels
www.cseannauniv.blogspot.in
Vijai Anand
CS2361–Internet & Java
5.8
Dynamic Hospital Information System The Dynamic Hospital Information System (DHIS) for a fictitious hospital named SK Hospital is developed using open source technologies: o Deployed on Apache Tomcat web server o JSP is used as server side scripting o Javascript is used as client-side scripting o MySQL is the RDBMS used for data driven pages o CSS is used to specify consistent formatting and presentation o XHTML markup is used to specify structure of the web document Install the following software: o JDK 1.6 or higher o Apache Tomcat web server 5.5x o MySQL 5.5 o Dreamweaver MX 2004 Home Page Create a folder dhis at C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps Copy all jsp, css, html files onto dhis folder. Create a folder images in dhis and place all the images there. The file index.jsp in dhis folder is the default document or home page. The home page includes a third party javascript from WOWSlider.com to rollover pictures of various facilities in the hospital A javascript to scroll text is also part of home page and is included as The home page is structured using
element instead of frames. The homepage contains image buttons that links to various specialties. The website can be viewed using URL http://localhost:8080/dhis
Stylesheet CSS document specifies formatting elements that bring consistent look and feel to the website. The following shows hospital.css stylesheet designed in Dreamweaver. /* hospital.css */ .vision { font-size: 13pt; font-style: italic; line-height: 125%; } .cp { font-size: 8pt; } .mission { font-style: italic; } p { text-align: justify; line-height: 125%; font-size: 13pt; } caption { font-weight: bold; color: #CC0033; } h2 { color: #FFFFFF; background-color: #0099FF; } …
The stylesheet is linked to xhtml documents using element as Client-side Scripting A number of forms were designed to collect data such as patient details, pathological reports, staff details, etc., using XHTML
