Design And Implementation Of HIS And PACS Gateway Based On HL7

With the increasing development of computer and network technology and the advancement of informationization, hospital information system has been playing an important role in hospital management. The majority of hospitals have established HIS (Hospital Information System), PACS (Picture Archiving and Communication Systems) and many others. The development trend of hospital informatization is identified as achieving the more compact information integration in medical institution and the more extensive information interconnection between medical institutions. However, there are still challenges, such as different configuration of hardware between systems and diversity of data structures and coding rules of the software, which may lead to the "Information Island". It is undoubted that the core issue for the development of medical information is the information sharing. Put it another way, medical information interchanging and sharing is an indispensable part of hospital informatization. Therefore, the adoption of standardized medical information is an inevitable trend.HIS is referred as a computer application system for hospital management and information management, covering almost all businesses of hospital and the information management in business process. PACS is referred as a medical image archiving and communication system, aiming to collect, store, manage, inquire and transfer medical images generated from by the modern digital equipment. The hospital information managed by HIS includes the image information and related management information in PACS. Thus it can be seen that there exists a information exchange between the two systems, which is also an inevitable part of informationization. In the final, the integration of HIS and PACS is all about information standards.Currently, the existing means of information exchange between HIS and PACS includes:accessing database of the other, creating the middle table, constructing the middleware, the distributed integration based on CORBA (Common Object Request Broker Architecture), and the way based on the HL7 standard (Health Level Seven). From the long-term perspective of the development, the way based on HL7 standard conforms to the trend of the development of the informationization. Meanwhile, it is the fundamental way to solve the system integration between HIS and PACS. This article aims to realize information exchange and sharing between HIS and PACS based on HL7 standard in accordance with international standards. The said means, with good system extensibility, can achieve seamless information connection and contribute to the sustaining and rapid development of informationization.HL7 is committed to create a criterion of electronic data and a criterion of information exchange between different healthcare system, applicable to communication among incompatible software and data structures in a heterogeneous system environment. As HL7 increasingly develops, it has been covering almost all of medical information businesses and recognized as the international standard of information exchanging, with more than 2,300 members from 36 countries and regions. In America, HL7 has been officially considered as a criterion of medical information, with a more than 95 percent of acceptance by about 95 percent hospitals. In addition, it has also been utilized by Canada, Germany, Japan or other else. Therefore, realizing information exchange and sharing based on HL7 is an inevitable trend.The study of HL7 starts late, and has not been followed by most of hospitals in China. Meanwhile, the domestic HIS development differs significantly. In order to realize the standardization of HIS, the localization of HL7 should be accelerated. For those HIS system in construction, we should observe HL7 to properly develop; for those that are put into use, standard reform should be conducted via the construction of HL7 gateway, which not only contributes the standardization of HIS, but avoid the waste of capital caused by system reconstruction.Most PACS follows the DICOM (Digital Imaging and Communication in Medicine) standard, which is the standard of medical images and related information. HIS and PACS aren’t followed a unified standard. By building the HL7 gateway, the integration between HIS and PACS and text transmission can be completed. By building the DICOM gateway, the reading and accessing of medical images can be reached. This paper aims to study the text transmission and sharing between HIS and PACS. By means of HIS and PACS Gateway based on HL7, we strives to perform a standard reform of the existing system and achieve the integration of HIS and PACS.This paper firstly introduces the HL7 standard (HL7 standard has two versions: HL7 V2. X and HL7 V3.0; this paper mainly focuses on HL7 V2.4; the construction of the message in this paper is based on HL7 V2.4), including:the development of HL7 standard, HL7 message structure, the communication principle and various development tools and software, etc. Then analyzing the imaging business process and information exchanging process between HIS and PACS was conducted. The exchange of information includes personal information, clinical information, order information, order status information, observation reporting information, image information, etc., According to the needs of business process and information exchange, we created the corresponding message based on HL7, including general order message for new order (ORM^O01 (NW)), general order message for cancel order request (ORM^O01 (CA))、query response message for order status (ORM^O01)、general acknowledgment message (ACK)、general order response message response to any ORM (ORR^O02)、Observation Reporting message(ORU^R01)、Master Files Change Notification message (MFN^M01) and so on. The detailed business processes are as follows:patients registered in the outpatient clinic or ward of a hospital; then went to relative department or ward to see a doctor; the doctor issued the order application according to patients condition; HIS would send a new order message (ORM^O01 (NW)) after price delimitation and charging; patients’personal basic information, clinical information, general order information were send to PACS, which would receive application information and handle those said patients’information; patients came to radiological department in the booking examination time and PACS was conducted to take separate examination for patients, and sent the query response message for order status (ORM^O01) to HIS according to the checking status of patients. If the patients were in check or finished the imaging examination, HIS is not allowed to cancel or modify the order. PACS sent the Observation Reporting message (ORU^R01) to HIS after the imaging examination, transferring the patients’image diagnosis, and image information to HIS. HL7 can only transmit text messages except for the actual image information. If the image information was observed, transmission system would transfer reference pointer to acceptance system. The RP value (reference pointer) in OBX of ORU^R01 must be used if the actual image is not sent in OBX but exists somewhere else. The doctor could use this reference pointer to access to the actual image through DICOM gateway during diagnoses and treatment, look up the observation reporting information from PACS, and review the current images or the former images by DICOM gateway for the final diagnosis and treatment.This paper presents a framework of an integrated HIS and PACS Gateway based on HL7 and elaborate each assignment management modules after determining the main message in accordance with the need of information exchange in the business process of HIS and PACS. The design of HIS and PACS Gateway based on HL7 mainly includes the following functional modules:an interface module, a message module, a format conversion module and a transmission module.The interface module services as a database interface for connecting the local database, responsible for inquire, update, delete and modify local data and so on. The message module is divided into four parts:a task management part, responsible for launching and receiving message task and connecting other modules; a message module part, responsible for constructing the application information into HL7 message based on the type of message; a parsing message part and a constructing message part as a reciprocal pair, response for resolving the message to the application data; a validation part, responsible for verifying the receiving messages. The format conversion module is responsible for converting the traditional vertical bar code format(ER7, Encoding Rules for7), which has the poor readability, into XML (Extensible Markup Language)format since it is good for network transmission, or converting the XML format into the traditional vertical bar code format. The transmission module includes log files, sending and receiving part. Log files are used for the information backup and recovery in case of accident. Sending and receiving part sends and receives messages following the TCP/IP network transmission protocol. HL7 server and HL7 client are constructed through adopting C/S mode, using socket to achieve point-point communication and realize the transmission of the message.This study was designed to construct a database via ORACLE database and PL/SQL Developer integrated development environment, construct and analyze massage via NHAPI, develop the gateway via C#.NET and show some implementation of gateway. Finally, the summary and prospect were conducted at the end of this paper.HIS and PACS gateway based on HL7 realizes the data integration of HIS and PACS, eliminates the information island and optimizes the business process. The electronic information interchanging and sharing reduces the manual input, the input error rate, improves the working efficiency, and safeguards the interests of patient. The sharing of electronic application order and diagnosis report reduces the use of paper and the waste of resources, contributing to environment protection. Meanwhile, the implementation of HIS and PACS gateway based on HL7, is beneficial for guaranteeing the security of data and the independence of system, reducing the coupling of the system, and expanding the extensibility and maintainability. It also promotes the development of health informatization.As for the informatization development of China, relevant institutions should accelerate the localization process of HL7, standardizing the healthcare information system and providing theoretical and professional guidance. The all-round development from theory to practice and responses to the call of medical system reform should be performed to promote the construction of hospital medical digitization and health informatization.