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TeleradiologTeleradiology – overview, y – overview, systems and systems and applicationsapplications
Dr Sanjoy Sanyal MBBS, MS, MSc (UK), ADPHA, ADHRD
Seychelles
Staff seminar on 27 July 2007 in Seychelles medical college
TABLE OF CONTENTSTABLE OF CONTENTS1. Definition / types of teleradiology2. Components3. Configurations4. Equipment specifications5. DICOM6. PACS7. Applications8. Telemammography9. Costs10. References
1. DEFINITION1. DEFINITION
Teleradiology: A means of electronically transmitting patient’s radiographic images and consultative text from one location to another
1. TYPES OF TELEMEDICINE1. TYPES OF TELEMEDICINE
2. COMPONENTS – Telemedicine 2. COMPONENTS – Telemedicine system in generalsystem in general
2. COMPONENTS – Basic 2. COMPONENTS – Basic teleradiology systemteleradiology system
A. Image sending station B. Transmission network C. Receiving/image review station
A. Image Sending StationA. Image Sending Station
Image (film) digitizer Network interface device (e.g. phone
modem)
Image (film) digitizerImage (film) digitizer
1. Direct digitization: No need for X-ray film and processing equipment (best)
2. TV camera digitizers (‘low-end’)3. CCD scanner digitizers (‘mid-level’)4. Laser scanner digitizers (‘high-end’)
– Last three digitizers perform same function: Input X-ray film → into scanner; analog image of film → digital image.
Camera digitizerCamera digitizer
Network interface deviceNetwork interface device
Film digitizer has converted the image to digital format
Data is sent to the modem upon command of the equipment operator
– Modem converts digital data into electrical impulses that are sent along transmission network.
B. Transmission NetworkB. Transmission Network
WireFiberopticsMicrowave
– Provided by telephone companies. This network utilizes both wire and fiberoptics
– Transmission speed (and cost) closely related to transmission mode.
C. Receiving / Image C. Receiving / Image Reviewing StationReviewing Station 1. Network interface (modem) 2. PC with storage medium (e.g. disc drive)3. One or two TV monitors 4. Optional hard copy device printer
Receiving/Image Review StationReceiving/Image Review Station
3. CONNECTION 3. CONNECTION CONFIGURATIONSCONFIGURATIONS
A. Point-to-point connection B. Local Area Network (LAN)C. Wide Area Network (WAN)
A. Point-to-point connectionA. Point-to-point connection
The basic sending and review station directly connected by a dedicated transmission network (e.g. a single wire or fiberoptic cable)
A. Point-to-point connectionA. Point-to-point connection
A. Point-to-point connectionA. Point-to-point connection
B. Local Area Network (LAN)B. Local Area Network (LAN)
Dedicated transmission networkMultiple sending / review stations attachedImages can be sent from several different
locations within a building (or cluster of buildings) to a review station
B. Local Area Network (LAN)B. Local Area Network (LAN)
C. Wide Area Network (WAN)C. Wide Area Network (WAN)
Many LANs interconnected - ‘super’ networkConnected by routersInterconnected LANs represented as ‘network
cloud’
C. Wide Area Network (WAN)C. Wide Area Network (WAN)
C. WAN – Telephone networkC. WAN – Telephone network Telephone network services can be thought of as a
WAN Widely used transmission network Advantages of using the telephone network
(1) It already exists
(2) Inner workings / complexities of network are transparent to end users
(3) Allows for readily available long / short distance connections
(4) Costs are low
Server-mediated communicationServer-mediated communication
Server-mediated communicationServer-mediated communication
4. EQUIPMENT 4. EQUIPMENT SPECIFICATIONSSPECIFICATIONS
A. Sending Station Specifications – Image resolution– Image compression– Transmission speed
Image resolutionImage resolution
Pixel: 512 x 512 (w x h), 1024 x 1024, or 2048 or 2048
Grey scale (density) number: 256 (8-bit depth) to 4096 (12 bit-depth)
File size: – 512 x 512 x 8 bit-depth = 2,097,152 bits – 1024 x 1024 x 12 bit-depth = 12,582,912 bits
(6 times larger file size)
Image resolution – pixels Image resolution – pixels
240 dpi 120 dpi 60 dpi 30 dpi
Image resolution – grey scaleImage resolution – grey scale
255 grey levels / pixel
15 grey levels / pixel
5 grey levels / pixel
2 grey levels / pixel
Image compressionImage compression
Compression algorithms: DCT
– Lossy: JPEG (common)
– Lossless: Huffman JPG; JPG-LS; RLECompression ratios: 2:1 to > 15:1
– < 3:1 is lossless
– > 3:1 is lossy
Image compressionImage compression
Image compressionImage compression
Image compressionImage compression
TransmissionTransmission
DS 0 (64 Kbps)ISDN (128 Kbps)T 1 (1.544 Mbps)ATM: Asynchronous Transfer Mode
Transmission speedTransmission speedBalance resolution, compression, and
transmission speed parameters
Transmission speedTransmission speed
4. EQUIPMENT 4. EQUIPMENT SPECIFICATIONSSPECIFICATIONSB. Receiving/Image Review Station
specifications – Modem: receiving unit modem must be >
maximum speed of sending station – Computer hardware – Image enhancement software– TV monitor: Resolution, size, split-screen,
brightness
Image enhancement softwareImage enhancement softwareGrey scale window/levelMagnification image enhancement Colour, grey-scale mappingPositive-negative reversalAnnotationMinificationEdge enhancementImage flip/rotateCine and histogram equalization
TV monitorTV monitorResolution: 512 x 512 pixels to 2048 x 2048
pixels Size: 14 – 21 inches Split-screen: Display 2 or more different
images at the same time Brightness:
– High footlamberts (greater brightness) better– Brightness differential between shades is greater– Easier for the human eye to detect
Digital display monitorsDigital display monitorsDigital display monitors: For decoding
digital images for producing diagnostic quality images for reporting
Quality concerns: Whether they can match image resolution of X-ray film– Pixel content: Lack of resolution is not because
of the pixel content; typically 2K pixels x 2K lines
– Level of contrast: The problem is with the level of contrast - usually <100 shades of grayscale
Digital display monitorsDigital display monitorsSpecial techniques for correcting deficiency:
– Histogram-based image transformation
– Filter-based image transformation
– Unsharp mask These techniques give radiologist the ability
to use ‘window’ and ‘level’ control (sort of contrast and brightness adjustments) to get adequate contrast distinction for confident reporting
Contrast-brightness controlContrast-brightness control
Digital display monitorDigital display monitor
5. DICOM5. DICOM
DICOM: Digital imaging & communication
ACR / NEMA standard: A set of rules
Medical scanners (US, CT, MRI, X-ray) store and exchange images in DICOM format.
5. DICOM5. DICOM
Allows exchange of images between digital imaging machines, computers and hospitals.
Allows teleradiology to expand from a vendor-dependent proprietary protocols and hardware to an open Internet-like system
DICOM imagesDICOM images
DICOM viewerDICOM viewer
6. PACS6. PACS
PACS: Picture Archiving and Communication System
For distribution, storage and management of digital images and patient information.
Aiming towards filmless hospitalWeb-based PACS (AMICAS® Inc): Diagnostic-
quality radiology image management services; secure image capture, distribution, workflow integration and image archiving.
PACS networkPACS network
7. APPLICATIONS7. APPLICATIONS
A. Radiologists on call B. Hospital physicians C. Primary care / rural physicians D. Tertiary subspecialty consultationsE. Computer-aided diagnosis (CAD)
A. Radiologists on callA. Radiologists on call
On-call radiologist uses portable telerad receiving station at home
Patient images transmitted from radiology dept to radiologist’s home for immediate review
B. Hospital physiciansB. Hospital physicians
ICU patient images taken in Radiology Department Quickly transmitted to ICU for review by the team
responsible for that patient's care Other involved physicians can also view images
C. Primary care / rural C. Primary care / rural physiciansphysicians
Primary physician can send images taken in the clinic to a radiologist in a distant location for reading and consultation
C. Primary / rural physiciansC. Primary / rural physicians
D. Tertiary super-specialist D. Tertiary super-specialist radiology consultationsradiology consultations
A community hospital radiologist can send a complete set of images to a tertiary super-specialist (i.e. paediatric radiologist)
E. Computer-aided diagnosisE. Computer-aided diagnosis
Processing / analyzing digital medical images on workstation allows computer assistance to physician for interpretation
Drawback: Increases number of negative / unnecessary biopsies without increasing incidence of positive diagnosis in mammography
E. Computer-aided diagnosisE. Computer-aided diagnosis
E. Computer-aided diagnosisE. Computer-aided diagnosis
7. TELEMAMMOGRAPHY7. TELEMAMMOGRAPHYMore women in remote areas
Mammography experts are in cities
Mammograms require special expertise
Mammogram films are 35-55 MB/film
WHY?
7. TELEMAMMOGRAPHY7. TELEMAMMOGRAPHYHigh resolution is must for minute lesions
So cannot compress images
So need high-speed transmission lines
Satellite and T1 is the answer
NASA is the satellite and telemedicine expert
7. TELEMAMMOGRAPHY7. TELEMAMMOGRAPHYSTN: Satellite Telemammography NetworkKa-Band satellites: Advanced
Communication Technology Satellite (ACTS)Earth stations: T1 VSAT (Very Small
Aperture Terminal)
– #1: Cleveland Clinic, OH
– #2: NASA Glenn Research Center @Lewis Field – ASCL
– #3: University of Virginia, Charlottesville
Satellite networkSatellite network
NASA satelliteNASA satellite
Earth station – NASA GlennEarth station – NASA Glenn
Earth station – University Earth station – University
Radiology - reading filmsRadiology - reading films
9. COSTS9. COSTSLow end equipment: $15,000 to $20,000High performance systems: > $100,000High quality sending station: ~ $35,000 to
$40,000Dual CRT receiving / viewing station:
$45,000 to $55,000(Figures are as of 1st half of this decade)
10. REFERENCES10. REFERENCESUniversity of Iowa:
http://www.radiology.uiowa.edu/MoreRAD/Teleradiology/Tele.html
Stephen Kinnear: http://www.scit.wlv.ac.uk/~c9581158/graphic/graphic.html
Sreedhar Raja: http://www.websamba.com/dicom4india
Chris Rorden: http://www.psychology.nottingham.ac.uk/staff/cr1/dicom.html#contrast
10. REFERENCES10. REFERENCESNHS Purchasing and Supply Agency, UK http://
www.pasa.doh.gov.uk/dme/radiology/pacs.stmOsman Ratib:
http://www.hon.ch/Library/papers/ratib.htmlNASA Glen Research Center:
http://web.archive.org/web/20051002003701/ctd.lerc.nasa.gov/5610/mammography/SLSandE.html
http://www.nasa.gov/centers/glenn/news/pressrel/97_telem.html
10. REFERENCES10. REFERENCESNASA Glen Research Center:
http://www.grc.nasa.gov/WWW/RT1995/5000/5660k2.htm
SNAB: http://ctd.grc.nasa.gov/organization/branches/snab/telemedicine.html
http://www.medicalimagingmag.com/issues/articles/2006-12_07.asp
Wootton and Craig. Introduction to Telemedicine. 1999.