Transcript slides

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)
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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.
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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
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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.
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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
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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
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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.
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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
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PACS Types of images
 Most PACSs handle images from various medical imaging instruments:
 Ultrasound
 MR
 Positron emission tomography
 Computed tomography
 Endoscopy
 Mammograms
 CT
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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)
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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.
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THE END
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