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.