Unit III Creating the Image

Chapter 26 Digital Image Management

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.4 Objectives Discuss advantages of using PACS in a medical imaging department Explain why a PACS network may require a separate computer network from the one used throughout an institution

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.5 Objectives Describe laser printers that can be used for digital images Explain soft-copy monitor display parameters

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.6 Objectives Identify types of storage available for digital images Discuss necessity for Digital Imaging and Communication in Medicine (DICOM) in medical imaging

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.7 Introduction Filmless environment has become possible today due to: –Faster data handling –High resolution monitors –Efficient storage options –Communication standardization

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.8 Introduction PACS –Hardware and software HIS/RIS Integration of the electronic medical record (EMR)

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.9 Digital Imaging Formats CR/DR Digital fluoro/angiography Computed tomography MRI Sonography Others

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.10 Image Acquisition Mini PACS Teleradiology Film digitizers –Laser digitizer –CCD digitizer

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.11 Laser Digitizer Laser scans film in raster pattern Light transmitted through film detected Converted into electronic signal and digitized

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.12 CCD Digitizer Light focused into a line shines through film Strikes linear array CCD detector A signal proportional to the amount of light striking the detector is sent to the computer

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.13 Image Distribution Network infrastructure and file management –Large impact on data distribution Images need to be distributed to radiologists and clinicians

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.14 Image File Size Dependent upon: –Matrix size –Bit depth

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.15 Gray Scale Bit Depth 8 – 32 bits –1 byte = 8 bits File size of pixel –Multiplied by bit depth and divided by 8 8 – 32 bit depth 1 – 4 bytes of storage

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.16 Bandwidth Controls the speed at which data can be sent over a network Bits per second –bps

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.17 PACS network Separate network allows for large data files to be moved quickly –LAN (local area network) –Ethernet Bandwidth 10 Mbps

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.18 Teleradiology WAN (wide area network) –Much slower Wireless networks –Currently even slower

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.19 PACS Difficulties Large files Limited bandwidth Special language Problems interfacing with HIS

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.20 HIS/RIS Hospital information systems –Database containing all patient medical record information except for radiology Radiology information systems –Radiology specific database

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.21 HIS/RIS Ideally want interconnected HIS/RIS –RIS then sends needed patient information to PACS

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.22 Filmless/Paperless Environment HIS registers patients and sends orders to RIS RIS generates worklist for the day PACS sends image and patient data to radiologist/clinician

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.23 Image Display Hard-copy display Soft-copy display

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.24 Hard-Copy Display Laser printers Dry processors

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.25 Laser Printer Components Laser source Collimator lens or beam shaping optics Beam modulator Deflecting mirror-shaping lenses Cylindrical deflection mirror Unexposed film storage Mechanical transport

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.26 Laser Printers 8 bit gray scale Light sources –Infrared ( nm) –Solid-state diode (~ nm) –Helium-neon (633nm)

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.27 Laser Printers Film exposed line by line in raster pattern Exposed film processed by dry or wet processor

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.28 Laser Printer Calibration

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.29 Wet Laser Film Contains silver halides Spectrally sensitive to red or infrared wavelengths –Will be fogged by red safelights Processed through developer, fixer, wash and dried

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.30 Dry Processors Thermally processed –Heat-sensitive film Silver-based emulsion Dye microcapsules Carbon-based adherographic printing

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.31 Silver-Based Emulsion Dry Processor Film Silver Benhate –Laser light creates latent image centers –Heat develops latent image centers

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.32 Dye Microcapsule Dry Processor Film Become permeable when exposed to laser Heat activates chemical processing Cooling causes processing to stop If stored in high heat film density can increase over time

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.33 Carbon-Based Adherographic Printing Film exposed to gallium arsenide laser Carbon particles adhere to areas exposed by laser Cover sheet sealed or laminated onto finished film

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.34 Dry Processor Film Shorter shelf life More sensitive to heat and humidity

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.35 Soft-Copy Display Monitors –CRT –Flat panel

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.36 CRT Components –Electron gun –Phosphor screen

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.37 CRT Electron stream –Raster pattern

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.38 Flat Panel LCD Monitors Light source shines on individual pixels Liquid crystal and hydrogenated amorphous silicon TFTs –Located between glass plates

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.39 Storage Typical large radiology department –150,000 examinations –3.2 Terabytes of memory 3-5 years of storage 16 Terabytes

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.40 Storage Short-term –Local hard drive –PACS server and RAID Long-term –Jukebox of disks or tapes

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.41 Storage Off-site –Ensures integrity if there is a catastrophic event

Copyright © 2006 by Thomson Delmar Learning. ALL RIGHTS RESERVED.42 DICOM Standards-based protocol created by joint efforts of ACR and the National Electrical Manufacturers Association (NEMA)