1. PACS system introduction

PACS (picture archiving and communication system) refers to the information system oriented on the medical picture archiving and communication system and focusing on the acquisition, transmission, storage and diagnosis of medical pictures. In the digital hospital construction process, PACS is both the emphasis and difficulty in the entire process.

In the PACS system, t he processing and standardization of image information, as well as the storage and transmission of pictures are the technical emphasis and difficulty in the entire system.

Image information processing mainly includes images storage and management, transmission and compression. The image storage and management should meet the requirements for high efficiency and functions. The images transmission network should be mainly formed by the customers hosts and servers, the network topological structure generally adopts the star-shaped structure. The commonly used image compression technology is the destructive compression, however, to ensure the quality of medical images, the basic requirement of directly accessing the entire system by linear storage and non-compressed images should be met.

By applying the PACS system, the following purposes may be achieved:

    （1） Fully sharing of hospital image resources

    （2） Establishing the fundamental and open medical image application platform

    （3） Effectively improve the clinical medical diagnosis level

    （4） Improving the hospital’s economic benefits

2. PACS SYSTEM DEAMNDS ANALYSIS

To build an information system meeting the above demands, the following problems have to be solved.

（1）Servers integration

 Through the server virtualization technology, the present business system of the hospital may be integrated into several high-performance virtual servers, through the high-available protection function of the virtualization technology, realize the mutual backup among multiple servers, implement flexible management on dynamic resource scheduling, so that to improve the flexibility of the entire application platform.

（2）Storage integration

Through storing the data on the original dispersed independent servers onto the professional and reliable storage system, the centralized management, distribution of storage resources may be realized, thus the storage utilization may be improved, the application servers realize the high-efficient access on storage through the high-performance interface, through the centralized storage, the data security and manageability of data may be improved, meanwhile, we may consider to use the high availability technology of storage to improve the reliability of data storage and access of the hospital’s business system, ensure the stable operation of the business system.

（3）Unified data backup

Through configurating the industrially most advanced integrated equipments and developing overall backup strategies, realize the rapid regular backup and recovery of the hospital’s HIS, LIS, EMR, PACS and other business systems and critical database systems, improve data security.

3. PACS SYSTEM PROGRAM DESIGN

For the building of HIS, LIS, EMR, PACS, RIS and OA, decision management and other application systems, constructing a dynamic and scalable computing resource pool through the cloud computing architecture is able to meet the demands of the present patient visiters for the IT resources at the information center, meanwhile, the entire IT architecture may be rapidly and seamlessly expanded, deployment of new business may be distributed directly in the computing resource pool, thus a lot of time may be saved. Additionally, resources may be distributed at any time to build test environment to test the development of new business systems.

PACS is quite different from HIS, LIS and other medical information systems, the most important point is the massive data storage. Reasonably designing the data storage structure for PACS is the key for successfully building the PACS. A large hospital may own a large quantity of large medical imaging equipments, the data generated in daily imaging examinations is up to 4Gb or around (uncompressed raw data), the annual data volume is up to 1200GB or more. With the rapid business growth and introduction of new imaging devices, the data volume may grow continuously. Additionally, how to improve the online data random storage and reading efficiency is another critical problem. For this reason, the existing suppliers of PACS medical imaging information system often adopt the HSM strategy, PACS storage may be divided into online storage and offline storage. Two types of storage medias with different performances are separately used to meet the requirements for high capacity and high efficiency, low-speed ultra large capacity storage device (offline storage server) is used for permanent storage; high-speed storage device (SAN or NAS) is used for online data storage, so that to ensure the extremely high storage and reading efficiency of online data. Historical data over 2 years is stored in the offline storage device, online storage device should be only used to store data generated in the last three years.

4. PACS system benefits

The construction program of the entire information system may achieve:

      1、Saving TCO up to 35-75%

• Through integrating multiple physical servers into one physical server, the software and hardware cost may be reduced by 40%. Integration ratio: production environment: 10-15:1, development test environment: 15-20:1.

• The average utilization of each server may be improved by 60-80% from 5-15%.

• The storage utilization may be improved by over 50%.

• About 70-80% operation cost may be reduced, including the data center space, cabinet, cables, power consumption, cooling and labor costs.

      2、Improving operation efficiency

• The deployment time differs from times to minutes, the server rebuilding and application loading timer: 20-40hrs=>15-30 min, 10,000people/h may be saved annually, to be calculated by 300 servers.

• Previously, hardware maintenance needs several days/weeks to prepare the changes and 1-3 hours of maintenance windows is required, presently, hardware maintenance and upgrades may be achieved without downtime.

      3、Improving service level

• Helping the user to establishment relationships between business and IT resources, enable IT resources to be appropriate to appropriate business priorities.

• Implementing unified management on all computing and storage systems as a large resource and implement dynamic resource distribution according to demands automatically.

      4、Uninterrupted on-demand capacity expansion

• Investment protection of old hardware and operating systems.

• The user does not need to concern about the compatibility of the old system, maintenance and upgrades and other series of problems.