Teleradiology

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Teleradiology

• C.Ruggiero

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• Introduction
• PACS
• Teleradiology systems state of the art
• Image acquisition, display, interpretation
• Image transmission
• Networks
• Image compression
• Lossless image compression
• Lossy image compression
• Examples
• The ACR-NEMA DICOM standard
• Information modelling in DICOM
• Network environment support in DICOM
• Conformance in DICOM
• The ACR standard for Teleradiology

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Introduction

• High band with communication capability - low
  cost acquisition of medical data in digital form
• Definition of teleradiology
• Description of possible applications
• Key points in teleradiology
• Teleradiology is the most mature of Telemedicine
  areas

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PACS

• Teleradiology originated from the need to manage
  images within departments and among departments.
• Research on Picture Archiving and Communication
  Systems (PACS) has brought about new capabilities
  for radiologists
• Major advantages of PACS

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Teleradiology systems state of the art

• Image acquisition and display
• Communication networks
• Image interpretation

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Image acquisition, display, interpretation

• Film digitization
• Computed radiography (CR)
• CT and MR scanners
• Frame grabbing
• Amounts of data to be transmitted

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Image transmission

• Networks
• main aspects to be taken into account
• Internet
• ISDN
• ATM

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Image transmission

• Image compression
• lossless image compression
• major advanced lossless tecniques DPCM, HINT,
  DP, BPE, MAR
• compression ratios 1.51 - 31
• lossy image compression
• growing evidence that lossy compression can be
  implemented without compromising diagnostic
  content
• requirements
• JPEG,
• subband coding wavelets

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Compression examples
Original image size 1,177,864 bytes
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GIF compression 545,463 bytes ratio 12.2
JPEG compression Optimized quality 127,246
bytes ratio 19.3
JPEG compression Optimized size 26,141
bytes ratio 145
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Original image size 1,989,536 bytes
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GIF compression 1,175,620 bytes ratio 11.7
JPEG compression Optimized quality 283,557
bytes ratio 17
JPEG compression Optimized size 39,690
bytes ratio 150
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Original image size 746,786 bytes
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GIF compression 315,683 bytes ratio 12.4
JPEG compression Optimized quality 89,200
bytes ratio 18.4
JPEG compression Optimized size 24,783
bytes ratio 130
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Zoom of previous image
Original size 65,589
JPEG compression Optimized quality 14,411
bytes ratio 14.6
JPEG compression Optimized size 3,731 bytes ratio
117.6
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The ACR-NEMA DICOM standard

• Introduction
• Version 1.0 1985
• Version 2.0
• Version 3.0 1992/1993 (DICOM)
• most important innovations with respect to
  version 1.0 and 2.0 use of information
  modelling, applicability to a networked
  environment, conformance

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The ACR-NEMA DICOM standard

• Information modelling
• advantages reduction of redundancy and ambiguity
• normalised object classes composite object
  classes
• established technique for uniquely identifying
  any object

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The ACR-NEMA DICOM standard

• Network environment support
• The International Standard Organisation (ISO) has
  set up a reference model for network
  communication
• DICOM fully conforms to ISO
• Communication protocols specified by DICOM are
  general purpose (OSI, TCP/IP).

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The ACR-NEMA DICOM standard

• Conformance
• DICOM defines the principles to be met by
  implementations claiming conformance
• DICOM specifies levels of conformance

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The ACR standard for teleradiology

• In 1994 the ACR has developed a standard for
  teleradiology
• This standard defines goals, qualification of
  personnel, equipement guidelines, licensing,
  credentialing, liability, communication, quality
  control and quality improvement