H T T P : / / W W W. AL I H AD I AN FAR D . I N F O / D O W N L O AD . H T M L
Further reading
Biomedical informatics computer applications in health care and biomedicine
(3rd edition), Edward H. Shortliffe, 2006 (chapters 9 and 18).
PACS and Imaging Informatics Basic Principles and Applications (2nd edition), H.
K. Huang, 2010 (chapters 1 and 7).
PACS A Guide to the Digital Revolution, Keith J. Dreyer, David S. Hirschorn,
James H. Thrall, Amit Mehta, 2010 (chapter 2)
What is medical imaging informatics?
It is a subfield of biomedical informatics that has arisen in recognition of the
common issues that pertain to all image modalities and applications once
the images are converted to digital form.
Medical imaging informatics embraces the following areas:
Image Generation : The process of generating the images and converting
them to digital form if they are not intrinsically digital
Image Manipulation: Uses pre-processing and post-processing methods to
enhance, visualize, or analyze the images
Image Management : Includes methods for storing, transmitting, displaying,
retrieving, and organizing images
Image Integration : The combination of images with other information
needed for interpretation, management, and other tasks (e.g. Patient
Because of
availability of
medical images
in digital form,
medical digital
images have
become a core
data type that
must be
considered in
Why medical imaging is important?
Diagnosis (Detection)
Treatment planning
Image-guided treatment, e.g. Image-guided surgery produced minimally
invasive surgery
Assessment of response to treatment
Estimation of prognosis
Medical communication
Medical imaging progress over time
1980s: Medical imaging technology development
Computed radiograph(CR), MRI, CT, Ultrasonography(US), Digital Radiography(DR), WS, storage, networking
Late 1980s: Imaging systems integration
• PACS, the American College of Radiology and the National Electrical Manufacturers Association (ACR/NEMA),
DICOM, high-speed networks
Early 1990s: Integration of HIS/RIS/PACS
• DICOM, HL7, Intranet and Internet
Late 1990s–present: Workflow and application servers
•Integrating the Healthcare Enterprise (IHE), ePR, enterprise PACS,Web-based PACS
2000s–present: Imaging informatics
• Computer-aided diagnosis (CAD), image contents indexing,
• Knowledge base, decision support,
• Image-assisted diagnosis and treatment
Parameters of image quality
Spatial resolution : Is related to the sharpness of the image; the
number of pixels (voxels) per image area.
Contrast resolution: Is a measure of the ability to distinguish
small differences in intensity; the number of bits per pixel
Temporal resolution: Is a measure of the time needed to create
an image
Energy sources to create images
X-rays: fluoroscopy, CT scan
Ultrasound: Ultrasonography
Nuclear Magnetic Resonance: MRI, positron-emission
tomography (PET) - nuclear-medicine imaging e.g.
radioactive isotope
What is PACS?
A Picture Archiving And Communication System (PACS)
consists of medical image and data acquisition, storage, and
display subsystems integrated by digital networks and
application software.
PACS Infrastructure
PACS infrastructure consists of a basic skeleton of:
hardware components (imaging device interfaces, storage devices, host computers,
communication networks, and display systems)
integrated by :
a standardized,
flexible software system for communication,
database management,
storage management,
job scheduling,
inter-processor communication,
error handling,
and network monitoring.
PACS Components
1) Data and Image Acquisition Gateways
2) PACS Server and Archive
3) Display Workstations (Diagnostic and Review)
4) Application Servers
5) System Networks
Data and Image Acquisition Gateways
PACS acquires images sent from imaging modalities (devices) and
related patient data from the hospital information system (HIS) and
the radiology information system (RIS).
There are two types of gateways (GW) to the PACS server and
archive, the database GW for textual data, and the image
acquisition GW for imaging data.
A major task in PACS is to acquire images reliably and in a timely
manner from each radiological imaging modality via the acquisition
GW, and relevant patient data, including study support text
information of the patient, description of the study, and parameters
relevant to image acquisition and processing through the database
Major functions of the PACS Server and Archive
• Receives images from examinations (exams) via acquisition gateways
• Extracts text information describing the received exam from the DICOM image header
• Updates the database management system
• Determines the destination workstations to which newly generated exams are to be forwarded
• Automatically retrieves necessary comparison images from historical exams from a cache
storage or long term library archive system
• Automatically corrects the orientation of computed or digital radiography images
• Determines optimal contrast and brightness parameters for image display
• Performs image data compression if necessary
• Performs data integrity check if necessary
• Archives new exams onto long-term archive library
• Deletes images that have been archived from the acquisition gateway
• Services query/retrieve requests from WSs and other PACS controllers in the enterprise PACS
• Interfaces with PACS application servers
Major functions of PACS workstations
Case preparation: Accumulation of all relevant images and information belonging to
a patient examination
Case selection: Selection of cases for a given subpopulation through DICOM
Image arrangement: Tools for arranging and grouping images for easy review
Interpretation: Measurement tools for facilitating the diagnosis
Documentation: Tools for image annotation, text, and voice reports
Case presentation: Tools for a comprehensive case presentation, including 3-D
image display for a large 3-D file, and fusion images
Image reconstruction: Tools for various types of image reconstruction for proper
Application Servers
Application servers are connected to the PACS server
and archive. Through these application servers, PACS
data can be filtered to different servers tailored for
various applications.
System Networks
A basic function of any computer network and protocol (TCP/IP) are to provide
an access path by which end-Users.
At the local area network level, digital communication in the PACS infrastructure
design can consist of low-speed Internet (10 Mbits/s signaling rate), mediumspeed (100 Mbits/s) or fast (1 Gbit/s) Internet, and high-speed asynchronous
transfer mode technology (ATM, 155–622 Mbits/s and up). In wide area
networks, various digital service (DS) speeds can be used, which range from DS-0
(56 kbits/s) and DS-1 (T1, 1.544 Mbits/s) to DS-3 (45 Mbits/s) and ATM (155–622
System Networks – continue
A low-speed network is used to connect the imaging modalities (devices) to
the acquisition gateway computers because the time consuming processes of
imaging acquisition do not require high-speed connection.
Medium and high-speed networks are used on the basis of the balance of
data throughput requirements and costs. A faster image network is used
between GWs and the PACS server because several GWs may send
large image files to the server at the same time.
High-speed networks are always used between the PACS server and WSs.
Storage Requirements
Compression methods
Lossless compression: Maximum compression ratios achievable with lossless
methods are on the order of 2:1 or 3:1.
Lossy compression: Compression ratios as high as 20:1 can be obtained with JPEG
compression, but with variable quality.
Wavelet compression: Wavelet compression at ratios as high as 80:1 for plain
films such as mammograms have being evaluated, and found to be satisfactory,
although ratios of more than 60:1 are rarely used.( in the JPEG 2000 standard)
).‫ مجموعه اي از موجهاست كه توسط مقياس هايي از موجك مادر بدست می آيند‬،‫(اصول موجك‬

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