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Medical Imaging
Lecture: Medical Image Formats
Dr. Engr. Sami ur Rahman
Assistant Professor
Department of Computer Science
University of Malakand
Reference Materials
 Reference Materials about Medical Image Formats (Important)
1. DICOM demystified: A review of digital file formats and their use in
radiological practice
R.N.J. Graham, R.W. Perriss, A.F. Scarsbrook
2. Image File Formats: Past, Present, and Future
 Richard H. Wiggins III, MD ● H. Christian Davidson, MD ● H. Ric
 Harnsberger, MD ● Jason R. Lauman, BS ● Patricia A. Goede, BS
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 2
Overview
 Joint Photographic Experts Group (JPEG)
 Portable network graphics format (PNG)
 Tagged image file format (TIFF)
 Digital Imaging Communications in Medicine (DICOM)
 Picture Archiving and Sommunication System (PACS)
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 3
Joint Photographic Experts Group (JPEG)
 Allows the user to specify how much compression is applied
 Exploit the fact that the human eye perceives small colour changes less
accurately than changes in brightness.
 Lossy Compression
 Disadvantage:
 Data are lost
 Advantage:
 A very small file size
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 4
Joint photographic experts group 2000
 Using lossless compression
 Allows lossless compression for certain region of interest (ROI), and
lossy compression for less critical parts of the image.
 Allows metadata to be embedded in the image file.
 JPEG 2000 is a new file format, and is not yet in wide use by
radiologists. With its advanced features it is predicted that it is likely to be
increasingly used in the future.
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 5
Portable network graphics format (PNG)
 Good features:
 Variable degree of transparency
 Image brightness control (gamma correction)
 The ability to embed text within the image file as so called “metadata”
 Lossles compression
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 6
Tagged image file format (TIFF)
 Llossless or lossy data compression can be specified
 The disadvantage:
 Large file size, not suitable for Internet or PowerPoint based applications.
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 7
Graphic interchange format (GIF)
 Uses lossless compression
 The compression is less efficient than PNG files (by about 5–25%)
 GIF has been largely superseded by PNG
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 8
Comparison of lossy and lossless image file
formats
Source
DICOM demystified: A review of digital file formats and their use in radiological practice
R.N.J. Graham, R.W. Perriss, A.F. Scarsbrook
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 9
DICOM
 DICOM = Digital Imaging and Communications in Medicine
 Standardized protocol and data format
 Connecting images with meta information
 Possibility to connect DICOM devices
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 10
DICOM
 A universal file type for medical images, developed to facilitate data exchange
between hardware, irrespective of manufacturer.
 12-bit grayscale images and color images
 DICOM images require software to be installed before they can be
opened and viewed.
 DICOM-viewing software falls into two main categories:
 Proprietary viewers, which are supplied with imaging systems such as CT or
magnetic resonance imaging (MRI) machines;
 And third-party DICOM-viewing software, either in the form of PACS or as a
stand-alone viewer for individual PCs.
 DICOM viewing software: Several free available
 DICOM files can be converted to a variety of image formats and edited
before use.
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 11
Picture archiving and communication system
(PACS)
 A medical imaging technology that provides
 Economical storage
 Convenient access
 Retrieval
 The universal format for PACS image storage and transfer is DICOM
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 12
PACS Types of images
 Most PACSs handle images from various medical imaging instruments:
 Ultrasound
 MR
 Positron emission tomography
 Computed tomography
 Endoscopy
 Mammograms
 CT
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 13
Components of a PACS system
 Database (server) (storage and managing ca. 1 TB/year)
 Workstation for image display
 Workstation for image processing
 All devices connected via a network (Protocol: DICOM)
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 14
Uses
 Hard copy replacement: PACS replaces hard-copy based means of managing
medical images, such as film archives.
 Remote access: It expands on the possibilities of conventional systems by
providing capabilities of off-site viewing.
 Electronic image integration platform: PACS provides the electronic platform for
radiology images interfacing with other medical automation systems such as
Hospital Information System (HIS).
 Radiology Workflow Management: PACS is used by radiology personnel to
manage the workflow of patient exams.
 PACS is offered by virtually all the major medical imaging
equipment manufacturers, medical IT companies and many independent software
companies.
University Of Malakand | Department of Computer Science | Visual Computing Research Group | Dr. Engr.Sami ur Rahman | 15
THE END
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