(I) Physical Hierarchy
From the physical hierarchy, PACS can be divided into four layers: network user layer, access layer, core
PACS Application Hierarchy Schematic
PACS Application Hierarchy Schematic
Central Layer, Resource Provisioning Layer, which constitutes a "pyramid" structure from the bottom up. The bottom-up structure consists of a "pyramid" structure. Among them: the network user layer is a large number of terminals or workstations in the network; the access layer refers to the terminal or workstation connected to the network user layer, for these terminals or workstations for the network interconnection of the collection of network equipment (such as secondary switches, hubs, etc.); the core layer refers to the access layer of network equipment together to form a full interconnection of the collection of network equipment, such as (server, router, firewall, etc.) ; Resource Provisioning Layer refers to the numerous medical device terminals in the PACS network, such as (CT, US, DR, etc.).
(2) Application Hierarchy
From the application hierarchy, PACS can be divided into three layers: MINI-PACS, departmental
PACS Application Hierarchy Schematic
PACS Application Hierarchy Schematic
PACS level PACS, and hospital-wide PACS, which constitutes an "embedded" structure from the inside out. MINI-PACS refers to the system planned for small medical institutions or a single department, and the MINI-PACS system must also include ultrasound, endoscopy, and other graphic and textual professional image reporting systems; department-level PACS refers to the departmental structure proposed for medium-sized hospitals, and tightly integrates with the hospital's existing HIS/RIS system to establish a patient-centered departmental imaging center; Hospital-wide PACS is a hospital-wide structure proposed for large hospitals, which fully realizes the digital reading and diagnosis workflow of all imaging departments and electronic management of all imaging departments in the hospital.
Workflow
Existing mainstream PACS vendors, at the beginning of the development of the PACS system, all comply with the following standard process.
PACS Business Flow Chart
PACS Business Flow Chart
(I) Registration Entry of Examination Information
The front desk registration workstation enters the patient's basic information and examination application information, and can also retrieve the HIS system (if the HIS exists and is fused with the PACS/RIS) to perform the automated entry of the patient's information, as well as the It can also automatically enter patient information by retrieving the HIS system (if it exists and is integrated with PACS/RIS), and carry out the work of triage registration, re-registration, scanning of application form, printing of application form, and triage arrangement for patients.
(2) WorkList Service
Once the patient information is entered, other workstations can directly and automatically recall it from the main database of the PACS system without having to manually re-enter it; medical imaging equipment with WorkList service can directly extract the list of relevant basic patient information from the server, and imaging equipment without WorkList function can enter patient information data through the medical imaging equipment operator console. Medical imaging equipment with WorkList service can extract the list of relevant basic patient information directly from the server.
(3) Image Acquisition
For standard DICOM devices, the acquisition workstation can automatically (or manually) forward images to the main PACS server after or during the examination.
(iv) Non-DICOM Conversion
For non-DICOM devices, the acquisition workstation can use the MiVideo DICOM Gateway to receive the registration information and then perform image acquisition during the examination process, and the acquired images are automatically ( or manually forwarded by the device operating technician) forwarded to the main PACS server.
(E) Image Access
After the patient completes the image examination in the examination room, the physician can access, browse and process the image through the network of the reading room, and can print out the film and deliver it to the patient.
The PACS system automatically recalls images from the main server disk array or the front server connected to it according to the path set in the background.
In the image display interface, the physician can generally carry out some measurements of length, angle, area and other image post-processing, in the mainstream PACS, in addition to the measurement function, will provide scaling, moving, mirroring, inverted, rotating, filtering, sharpening, pseudo-coloring, playback, window width and window position adjustment and other image post-processing functions.
(F) Report Editing
After the patient completes the imaging examination the image quality is reviewed by the professional staff and quality analysis is performed. After completing the quality review and control of the image, the diagnostic doctor can edit the diagnostic imaging report, and according to the diagnostic physician's authority, respectively, the initial diagnosis report, report review work. In the process of writing the report, a template of commonly used diagnostic words can be used to reduce the physician's keyboard input workload. In the process of diagnostic report auditing, the modified content can be modified to retain traces, can obtain the clinical diagnosis, detailed medical history, history of diagnosis and other information, can store the report as a typical case for other similar diagnosis, for the entire department to learn to improve the use of the department.
Audit completed report through the printer output by the physician's signature and submit, while the diagnostic report is uploaded to the main server storage backup. After printing the completed report can not be modified, but can be read-only access to reference.
6 architecture data
Storage technology architecture
PACS is different from HIS, LIS and other medical information systems, the most important point is: massive data storage. Reasonable design of PACS data storage structure is the key to successful construction of PACS. A large hospital has a large number of modernized large-scale medical imaging equipment, the daily image examination of the amount of data generated by up to 4 GB or so (uncompressed raw data), the total amount of data a year more than about (1200GB). With the rapid development of the hospital's business and the introduction of new imaging equipment, this amount of data is likely to grow further. In addition, how to improve the efficiency of online data random access is also a very critical issue.
For this reason, existing PACS medical imaging information system providers tend to adopt a hierarchical storage (HSM) strategy, which divides PACS storage into two levels of structure: online storage and offline storage. Two different performance storage media are used to fulfill the requirements of high capacity and high efficiency respectively. Low-speed ultra-large capacity storage devices (offline storage servers) are used for permanent storage; high-speed storage devices (SAN) are used for online data storage to ensure extremely efficient access to online data. For more than 2 years of historical data saved in the offline storage device, online storage device only save the last three years of data.
File formats
DICOM files are medical files stored according to the DICOM standard.
DICOM files consist of multiple datasets. A dataset represents the relevant attributes of a real-world information object, such as patient name, gender, height and weight. A data set consists of data elements that contain the values of the attributes of the encoded information objects and are uniquely identified by data element tags. Data elements have three structures, two of which have a type representation VR (the presence or absence of which is determined by the transport syntax) and differ in the way their length is expressed, and one of which does not include a type representation. The type representation specifies what type of data is stored in the data element, and is a string of length 2. For example, a data element with a VR of FL indicates that the type of data stored in the data element is floating point. All data elements contain a label, a value length, and a data value body.
The label is a 16-bit unsigned integer pair, in sequential order including the group number and element number. Data elements in a dataset shall be organized in increasing order of the data element tag number and shall appear at most once in a dataset.
The value length is a 16- or 32-bit (depending on explicit VR or implicit VR) unsigned integer that indicates the length of the exact data value, recorded by the number of bytes (which is even). This length does not include the data element label, VR, or value length fields.
The data value body indicates the value of the data element, whose length is an even number of bytes, and the data type of this field is explicitly defined by the VR of the data element. The data element field consists of three public *** fields and one optional field.
Data structure
Take the mainstream SUPER PACS system in the current Guangdong market as an example.
The current SUPER PACS system database*** has 36 tables, which are categorized according to their uses: public tables, digital film room-specific tables, radiology-specific tables, ultrasound-specific tables, remote-specific tables. Among them, the four main tables that play a key role are Patient, Study, Series and Image.
The Patient table is used to store the basic information of the patient, and the application scope involves all the subsystems of SUPER PACS; the Study table is used to store the examination information of the patient, and the application scope involves all the subsystems of SUPER PACS; the Series table is used for the generation of the sequence table of the image, and the application scope involves SUPERPACSR DICOM radiology system; Image table is used to hold system image records.