Typical X-ray machine · PDF fileX-RAY MACHINES Portable max output 20mA, 80KV ... • Dirt on plate or in scanner will create white artifacts ... • Using Charge Coupled Device CCD
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Veterinary Imaging Past, Present and Future-
Digital RadiographyROBERT H. WRIGLEY
Professor Veterinary Diagnostic ImagingUniversity of Sydney
Veterinary Teaching HospitalProfessor Emeritus Colorado State University
Light (projection) beam diaphragm with adjustable Lead Shutters
X-RAY MACHINESPortable max output 20mA, 80KV
50 mA 100KVHigh Frequency
X-RAY MACHINESCeiling mounted, 2000mA 150KV
Automatic Film Processors 1960sDry, Processed Film in 90 seconds
Courtesy Konica
• Underdevelopment• From under replenishment per film• From developer oxidization in too large a
storage tank
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Photographic film incassette
RARE EARTH SCREEN-FILM
SINGLE EMULSION FILM SINGLE ‘FINE’ SCREEN • INCREASED DETAIL• INCREASED
EXPOSURE• INCREASED
RADIOGRAPHIC CONTRAST
Computerised X-ray machine operating controls at the X-ray tube
Courtesy of SEDECAL USA Inc.
Radiology in the 20th Century Diagnostic Imaging in the 21st Century
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Digital Radiography Film Radiography
• Film
• Darkroom Film Processing
• Light Box
• X-Ray Capture Device
• Conversion to DICOM computer file
• Display on Workstation Monitor
•Digital Imaging & Communications in Medicine
Digital Radiography Film Radiography
• Paper envelope• File shelves
• Hand/mail delivery
• Image optimization software
• Computer file/folder• PACS Computer
database/archive•Electronic delivery
•Picture Archive & Communication Systems
Image Auto correction of Image WhitenessThis feature is available on some Systems
-Simplifies X-ray Technique setting
-If not a feature vendor must provide an accurate technique chart and patients measured and exposed as you would for film. Latitude allows for some manual correction of mild over orunder exposure
ADVANTAGESFilm/Screen
80 KVp 44mAs
DR Image processed with automatic correction selected80 KVp 44mAs
Film/Screen60 KVp16mAs
DR Image processed with automatic correction selected60 KVp 16mAs
Advantages of Filmless Digital Imaging Versus Film Radiography
- Film - Processing supplies- Darkroom - Film jackets & Files
• Electronic distribution of images via Networks– For diagnosis– For consultation/second opinions– Input into an electronic medical record
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DISADVANTAGES
• Need to be a skilled computer user• Need computer support personnel• All systems more expensive than
film/screen cassettes and an automatic processor
• Image detail less than good quality radiographs
Courtesy Fuji Medical Syst.
Exposure settings- those appropriate for > 400 speed FS and faster result in suboptimal CR image detail- Exposure settings as used for 300 speed FS and higher exposures are optimal for CR imaging- Newer systems using double sided plates and other plate halides now allow exposure to be significantly reduced.
X-Ray exposure level effects Image detail
Some systems provide feed back information on the radiation level to the patient.
What has been the effect on resolution of bony detail?
Digital ImageRectangular matrix of differing colored squares
(Pixels=Picture Elements)
Detail Resolution dependent on:• Pixel size – proportional to total number and size of pixels
-- physical size/quality of computer monitor-- quality of computer video card
2000 Pixels 64 Pixels
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5
0
0
P
I
X
E
L
S
80
P
I
X
E
L
S
Resolution
~ 15 Lp/mm~ 5 Lp/mm~ 3 Lp/mm
30 um2
100 um2
160 um2
DiodesTransistors
Dental2,256x28782,208x2688
Digital RadiologyDetectors5 x 7.5cm22 x 27cm35 x 43cm
5-15 Lp/mmMicroscoptic
CrystalsFilm/screen(all sizes)
Spacial ResolutionLine Pairs/mm
Pixel sizeMatrix# of Pixels
AcquistonDevice
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~ 15 Lp/mm~ 5 Lp/mm~ 3 Lp/mm
30 um2
100 um2
160 um2
DiodesTransistors
Dental2,256x28782,208x2688
Digital RadiologyDetectors5 x 7.5cm22 x 27cm35 x 43cm
5-15 Lp/mmMicroscoptic
CrystalsFilm/screen(all sizes)
~ 15 Lp/mm~ 5 Lp/mm~ 3 Lp/mm
30 um2
100 um2
160 um2
DiodesTransistors
Dental2,256x28782,208x2688
Digital RadiologyDetectors5 x 7.5cm22 x 27cm35 x 43cm
5-15 Lp/mmMicroscoptic
CrystalsFilm/screen(all sizes)
Courtesy Eklin
~ 15 Lp/mm~ 5 Lp/mm~ 3 Lp/mm
30 um2
100 um2
160 um2
DiodesTransistors
Dental2,256x28782,208x2688
Digital RadiologyDetectors5 x 7.5cm22 x 27cm35 x 43cm
5-15 Lp/mmMicroscoptic
CrystalsFilm/screen(all sizes)
Courtesy Eklin
American College of RadiologyTeleradiology Display Monitor Standard (1999)
• Real size display of human chest= 35 x 43cm film ~monitor 53cm diagonal size
• Resolution not < 2.5 lead lines per mm> 2000K x 2500 pixels (5 Mega Pixels)
2 Mega Pixels
1600 x 1200 3 M Pix 5 M Pix
Monochrome BW Medical DICOM factory calibrated LCD MonitorsResolution
600x8001200x1600
2 Mega Pixel2000x25001200 x16002400 x 3200
Variable53cm
diagonal35 x 43cmZoom x 2Then Pan
Computer MonitorsConsumer Level --------High End -----------------Medical-US,CT ---------Radiographic ( not ACR std)
2,208x26882,256x2878
35 x 43cm22 x 27cm
DR detector
2000x25005 mega pixel
35 x 43cmACR displaystandard
Pixel MatrixSize
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Pan to view remainder of the magnified image
Contrast Resolution dependent on:• Brightness of monitor• Number of colors per pixel (bits)• Grey scale images (Radiographic images, grey scale is 1/3rd
of total number of colors)• Dependent on -- quality of video card (number of colors)
-- quality of computer monitor10 bits (1,024) 8 bits (256)
Brightness of Light Boxes
2 Mega Pixels
1600 x 1200 3 M Pix 5 M Pix
Monochrome BW Medical DICOM factory calibrated LCD Monitors
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Liquid Crystal DisplayLCD Grayscale Monitors
Now preferred as brighter and more stable than TV type monitors
32cm x 43cm
Black/White
DICOM Calibrated Gray Scale
High Brightness
(>600 cd/mm2)
10 bit video card
Self calibrating
1022 Gray tones
$4-15,000
Monitor Display Test Pattern
Courtesy of www.animalinsides.com
generates digital radiographic images (computer files) from scanning a reusable
radiation sensitive imaging plate
Computed Radiography (CR=DR)
Film CR SPATIAL RESOLUTION6 pixels/mm (for 35 x 43cm )8 pixels/mm (for 24 x 30cm)
10 pixels/mm (for 18 x 24cm)
Courtesy of IDEXX Labs. Inc
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Reading the Imaging Plate
TranslationTranslation
LaserLaser
PM TubePM TubeRotating PrismRotating Prism
Imaging PlateImaging Plate
LightLightGuideGuide
Resolution
~5 Lp/mm~2.5Lp/mm~7 Lp/mm~5 Lp/mm
Adjustableby laser beam
10/mm5/mm
15/mm10/mm
MicroscopicCrystals
3520x42801760x21403000x37501770x2370
CR Plate
35x43cm
24x30cm
5-15 Lp/mmMicroscopicCrystals
Film/Screen
SpatialResolution
Line Pairs/mm
PixelsMatrix(Pixels)
Acquisition Device
CR SCANNERS
Melbourne and CamdenUni Vet Hospital Fuji CAPSULA
Courtesy of IDEXX Labs. Inc
Courtesy Agfa HealthCare
Courtesy of IDEXX Labs. Inc
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Loading Cassette
Courtesy of IDEXX Labs. Inc
Anatomic specific Image Processing
Courtesy of IDEXX Labs. Inc
Unloading Cassette
Courtesy of IDEXX Labs. Inc
Scattered Radiation
CR Plate
CR Specific Image Artifacts
The term originates from moiré in its French form, a type of textile, traditionally of silk but now also of other fibers, creating a rippled appearance.
Superposition of 2 similar patterns rotated by an angle α
2 sets of parallel lines inclined at an angle 5 degrees to one another
CR image made with a stationary grid 110 lines per inch.
What is the image quality artifact?
Moireproblem
How to stop this?
-Use a Bucky
-Turn the grid lines right angle to scan axis
-Replace with a grid recommended by CR vendor,180-230 lines per inch EXPENSIVE
* FOGGING BY SCATTERED X-RAYS & BACKGROUND RADIATION
Erasing Plates
Courtesy of IDEXX Labs. Inc
• Dirt on plate or in scanner will create white artifacts• CR Plates and the Scanner need to be cleaned regularly• Plus Image mottle from too low an X-ray exposure
Clipping of the thinnest densities of the lungs from over exposure
OriginalBeyond the range of manual correction
Non Automated system Clipping of the thickest densities of the spine
ORGINAL
Beyond the range of manual correction
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SMALL AREA DENTAL RADIOGRAPHY “DR”
ELECTRONIC PLATE X-RAY DETECTORS
FILM LESSDental Digital Radiography
• Using Charge Coupled Device CCD (light detector in digital cameras) – small size ~ 2”-3”
• SMALL AREA RADIOGRAPHY- DENTAL RADIOGRAPHY
• X-Ray Intensifying Screen directly attached to CCD under computer control
• Images displayed on computer in a few seconds• Pixel size 30 um2
• Resolution 15 Lp/mm
Dental Radiography, “DR”
Courtesy Alameda Animal Hosp.www.afpimaging.com
Digital Dental Radiographs Large Area CCD “DR” RadiographyAim to Record Image of a 14”x17” Region
(14” x 17” X-Ray Intensifying Screen)Image Recorded on Small CCD Chip (camera technology)
Courtesy of SEDECAL USA Inc.
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Vet Ray Technology
Courtesy of SEDECAL USA Inc.Courtesy of www.innovet4vets.com
Large Area Single CCD Chip “DR” Radiography
• Problems: – Bulky device – Inefficient collection of light, limits resolution– Built in grid will increase exposure need for
extremity imaging– Precludes using horizontal beam radiography– May require higher X-ray exposures than
film/screen and other digital acquisition devices
Large Area Multiple (Tiled) CCD Chips
– Smaller in size– Improved collection of light
– Stitching of input from adjacent CCD chips may create artifacts
4”Courtesy of RF System Lab
Digital Radiology Plate TypesIndirect Types Direct Types
www.idexx.com/animalhealth/digital/dR
Laser scanned
No scanning
image processing
No scanning
Anatomic specific
processing
Anatomic specific image
processing
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ADVANTAGES• Eliminate cassettes• Patient side image viewing
Portable System Customized for Veterinary Imaging Indirect DR detector