1. Computed Radiography and Digital Radiography

2. filmless’ radiology departments
Diagnostic radiographers
have traded their ______ and _________
for a __________ and __________
advance for Rad Sci Prof, 8/9/99

3. What Is Digital Imaging?
Digital imaging is the
acquisition of images to
a computer rather than
directly to film.
FOR MANY YEARS WE HAVE BEEN PUTTING IMAGINES ONFILM RATHER THAN INTO A FILM

4. New Technology Has impacted everyone:
Practicing radiologic technologist
Educators
Administrators
Students in the radiologic sciences.
READ NOTE
The phenomenal growth of new knowledge is especially difficult because of the complexity of much of the new information. In addition, new approaches to this new knowledge demand new methods
There is general agreement among educators and professional leaders that graduates of programs in the radiologic sciences should be both competent and involved professionals. They should be committed to improving their skills and defining their values through lifelong learning

5. Computed Radiography
Fundamentals of
Computerized
Radiography

6. Radiology Radiology 2001

7. CR SYSTEM COMPONENTS CASSETTES (phosphor plates) ID STATION
IMAGE PREVIEW (QC) STATION
DIGITIZER
VIEWING STATION
Cassettes are made of lightweight plastic. Backed by a thin sheet of sluminum that absorbs xrays. Has antistatic material (felt) that protects against static, dust, and mechnical damage.
Phosphor plates have barium fluorohalide crystals. Remant beam interacts with the electrons of the crystals and stimulates or gives energy to the electrons allowing them to be trapped until they deteriortae or the plate is read. Trapped signals can remain for days but they begin to deteriorate immediately. The active layer or the phostimulable phosphor layer is the where the electrons are trapped during exposure.

9. History of CR
INDUSTRY
Theory of “filmless radiography” first introduced in 1970
1981 Fugi introduced special cassettes with PSP plates (replaces film)
Technology could not support system
First clinical use in Japan

10. Predictions
1980 – Bell Labs believed that Unix would be the worlds dominant operating system
1982 – Bill Gates thought 640K of main memory would suffice for workplace operating systems ( This presentation is 80,000 kb)
1984 – IBM predicted that personal computers would not amount to anything

11. History of CR By 1998 – over 5,000 CR systems in use nationwide
1998 – Local area hospitals begin to incorporate CR systems in their departments
(Riverside Co. Hosp builds new hospital in Moreno Valley) – completely CR system – 1st generation equipment

12. TERMINOLOGY F/S - ______________________ CR - _____________________
DR _____________________
DDR - _____________________

13. IMAGE CREATION SAME RADIOGRAPHY EQUIPMENT USED
THE DIFFERENCE IS HOW IT IS
___________

15. Conventional vs. Digital Imaging
Conventional X-ray imaging systems
Produce an analog image (radiographs, & fluoroscopy).
Using x-ray tube with films & cassettes
Analog image is the film/screen combo.

16. Conventional vs. Digital Imaging
Digital radiography systems require that the electronic signal be converted to a digital signal –
Using x-ray tube –
CR cassettes with phosphor plate (PSP)
DR systems with transistors (TFT)

17. COMPUTED RADIOGRAPHY & DIRECT RADIOGRAPHY & FILM SCREEN IMAGE CAPTURE
FS - Film inside of cassette
CR – Photostimuable Phosphor Plate (PSP)
DR(DDR) - Thin Film Transitor (TFT)

18. Cassette with film CR with PSP

19. We have the xray tube but we have an imaging plate.

20. Directed Digital Radiography (DDR)
Directed digital radiography, a
term used to describe total
electronic imaging capturing.
Eliminates the need for an image plate altogether.
There is no cassette at all. Supposed to be faster, digital is faster the CR.

21. Transitor underneath the xray table
Transitor underneath the xray table. You can instantly see the image on the screen outside the room.

22. Amorphous Selenium detector technology for
DR Direct Radiography
Transitors are coated with amorphous selenium.

23. Patient is missing a shield
Patient is missing a shield. This is a lot faster but it is a problem for an educator. It is hard to know if they always have someone around with them when they do repeats.

24. Transitor is in the bucky itself. A little less convenient.

25. IMAGE CAPTURE _____________ _____________ – No cassette-
PSP – photostimulable phosphor plate
Replaces film in the cassette
_____________ – No cassette-
Photons captured directly onto TFT
Sent directly to a monitor
CR:This is an indirect digital system.

26. CR vs. FS CR FILM PSP in cassette Film in cassette Digital image
Scanned & read- CR reader
COMPUTER
Image stored on computer
Viewed on a Monitor
Hard copy (film) can be made with laser printer
FILM
Film in cassette
loaded in a darkroom
Processed in a processor
Hard copy image – stores the image
Viewboxes – view the images

27. CR BASICS
Eliminates the need for film as a recording, storage & viewing medium.
PSP Plate – receiver
Archive Manager – storage
Monitor - Viewing

28. PSP cassette exposed by conventional X-ray equipment.
General Overview CR
PSP cassette exposed by
conventional X-ray equipment.
Latent image generated as a matrix of trapped electrons in the plate.

29. CR – PSP plate Photostimulable phosphor (PSP) plate Captures photons
Stored in traps on plate (latent image)
PLATE scanned in CR READER

30. CR Phosphor Plates ABSORPTION EMISSION X-RAY LIGHT LASER STIMULATION
ELECTRON
TRAP
ELECTRON
TRAP
X-RAY
LIGHT
Raster pattern scans the phosphor plate.

31. CR – PSP plate Stimulated by a ________________ LIGHT
Energy is ________ in a form of _____ light
LIGHT captured by photomultiplier tube (PMT)
Changed to a __________________ signal

32. How CR works
Blue released light is captured by a PMT (photo multiplier tube)
This light is sent as a digital signal to the computer
The intensity _________ of the light – correlates to the ______ on the image

33. ADC – analag to digital convertor.
Red blue and white lights.

34. The CR system is not much faster than film screen cassettes
The CR system is not much faster than film screen cassettes. It is really not faster it is just different. We can manipulate the image and it is better quality images.

36. CR “PROCESSORS”
Mulitloader cassette, loads 7 images at a time. The one on the right can only do 4 at a time.

37. Densities of the IMAGE
The light is proportional to amount of light received
Digital values are then equivalent (not exactly the same) to a value of optical density (OD) from a film, at that location of the image

38. Histogram. The higher the plot the more black there is on an image.

39. Each image has its on algorithm.

40. ERASING PLATE After image is recorded
Plate is erased with high intensity _______________________ light
Cassettes are reused

41. CR VS. DR
CR -______________ where the image is first captured on plate and stored = then converted to digital signal
DDR -____________ where the image is acquired immediately as a matrix of pixels – sent to a monitor

42. Digital Radiography Direct Capture Indirect Capture Computed
(CR)
Direct-to-Digital
Radiography
(DDR)

43. DIRECT RADIOGRAPHY Uses a transistor receiver (like bucky)
Captures and converts x-ray energy directly into digital signal
Images seen immediately on monitor
Sent to PACS/ printer/ other workstations FOR VIEWING

44. CR vs DR CR Imaging plate Processed in a Digital Reader
Signal sent to computer
Viewed on a monitor DR
Transistor receiver (like bucky)
Directly into digital signal
Seen immediately on monitor

46. Image Resolution – (how sharply is the image seen)CR
4000 x 4000
Image only as good a monitor*
525 vs 1000 line
More pixels = more memory needed to store
CR 2 -5 lp/mm
RAD 3-6 lp/mm
DR ?
IMAGE APPEARS SHARPER BECAUSE CONTRAST CAN BE ADJUSTED BY THE COMPUTER –
(DIFFERENCES IN DENSITY)

47. ADVANTAGE OF CR/DR Can optimize image quality
Can manipulate digital data
Improves visualization of anatomy and pathology
AFTER EXPOSURE TO PATIENT

48. ADVANTAGE OF CR/DR Changes made to image after the exposure
Can eliminate the need to repeat the exposure

49. ADVANTAGE OF CR/DR vs FS
Rapid storage
Retrieval of images NO LOST FILMS!
PAC (storage management)
Teleradiology - long distance transmission of image information
Economic advantage - at least in the long run?

50. CR/DR VS FILM/SCREEN FILM these can not be modified once processed
If copied – lose quality
DR/CR – print from file – no loss of quality

51. “No fault” TECHNIQUES F/S: RT must choose technical factors
(mAs & kvp) to optimally visualize anatomic detail
CR: the selection of processing algorithms and anatomical regions controls how the acquired latent image is presented for display
HOW THE IMAGE LOOKS CAN BE ALTERED BY THE COMPUTER – EVEN WHEN “BAD” TECHNIQUES ARE SET
F/S: RT must choose technical factors
(mAs & kvp) to optimally visualize anatomic detail
CR: the selection of processing algorithms and anatomical regions controls how the acquired latent image is presented for display
HOW THE IMAGE LOOKS CAN BE ALTERED BY THE COMPUTER – EVEN WHEN “BAD” TECHNIQUES ARE SET

52. DR Initial expense high Very low dose to pt –
Image quality of 100s using a 400s technique
Therefore ¼ the dose needed to make the image

53. Storage /Archiving FILM/SCREEN Films: bulky Deteriorates over time
Requires large storage & expense
Environmental concerns
CR & DR
8000 images stored on CD-R
Jukebox CD storage
No deterioration of images
Easy access

55. Transmission of Images
___________ - Picture Archiving & Communications System
____________- Digital Images & Communication in Medicine
__________ -Remote Transmission of Images

56. When started they did not have the same computer language
When started they did not have the same computer language. Now they all use DICOM.

57. Benefits of Computer (web)-based Viewing Systems
Hardcopy studies are no longer misplaced or lost- eliminates films
Multiple physicians may access same patient films
Patients do not have to wait in Radiology for films once study is completed

58. “Film-less” components
CR or DR
CD-ROM or similar output
capability
Digitizing capability or service
This slide describes some of the components necessary to make radiology departments filmless.
CR and DR are machines that will replace the standard X-rays we take, and will produce digital images of the pictures taken. (MRI, CT and Ultra Sound pictures are taken as a routine course in digital mode – but are generally converted to film for viewing because there are no digital viewing stations and software).
CD-ROM’s allow radiologists currently to disperse images to attending or referring physicians, via US mail or delivery services
Ideally, these images could be transferred electronically over the internet or via .
To take existing film to digital mode, it will require hospitals to have the film “digitized”.

59. PACS Internet VPN Digital Images Archive Remote Facilities Database
and Workflow Engine
Internet VPN
Workflow of a PACS system.
Picture is taken.
Picture is sent to Database/Workflow engine and then either to a local viewing station (for current diagnosis), to an archive for future retrieval, or
via an Internet Virtual Private Network (VPN) to offsite storage or to a remote viewing station.
Workstations
Remote Workstations

60. Histogram Analysis A histogram is a plot of gray scale value
vs. the frequency of occurrence
(# pixels) of the gray value in the image

62. HISTOGRAM – a bar graph depicting the density distribution (in numerical values) of the imaging plate
ALGORITHM – a set of mathematical values used to solve a problem or find an average
Algorithm is assigned to each body part.

63. Adapted from AAPM TG10

64. Each pixel is scanned. And a scale is assigned.

65. Statistical plots of the frequency of occurrence of each pixel's value

66. Basics of Digital Images
Digital images are a (matrix) of pixel (picture element) values
Computer can see 256 shades of gray.

67. Our eyes can only see 36 shades of gray
Our eyes can only see 36 shades of gray. The computer gives more varieyt and a clearer image.

68. The algorithm attempts to distinguish among the parts of the histogram which represent the range of densities from bone to soft tissue

69. Histograms set for specific exams (body parts)
Should produce digital images that are consistent (regardless of kVp or mAs used)
Correct Algorithm (body part) must be selected prior to processing imaging plate

70. Wrong algorithm on the left side.

71. Methods to Digitize an Image
1. _________ - Teleradiography system (PACS, DICOM)
2. ________ (vidicon or plumbicon)
3. _____________ _______________
4. _____________ _______________

72. FILM DIGITIZER

73. Analog vs Digital ______________ - one value blends into another
like a thermometer
______________ - distinct separation
98.6
exact
Analog is not exact. Where digital is an exaxt.

74. ANALOG TO DIGITAL IMAGE
Conversion of conventional analog films
To digital format for PACs and teleradiology applications
With scanning laser digitizers

75. CONTRAST & DENSITY
Most digital systems are capable of 1024 shades of gray –
but the human eye can see only about 30 shades of gray
The Optical Density and Contrast can be adjusted after the exposure by the Radiographer.
This is POST - PROCESSING

76. High displayed contrast – narrow window width
Short scale of contrast. Different algorithms
High displayed contrast – narrow window width

77. Low displayed contrast (stretched) – wide window width
Long scale of contrast
Low displayed contrast (stretched) – wide window width

78. Basics of Digital Images
Pixel values can be any bit depth (values from 0 to 1023)
Image contrast can be manipulated to stretched or contracted to alter the displayed contrast.
Typically use “window width” and “window level” to alter displayed contrast

81. 80 KVP 5 30 5 15
100
200
500
These all look the same regardless of the dosage given to the patient. This a a concern because technologists can overexpose patients.

82. Then the COMPUTER corrects any exposure errors
Therefore almost ANY technique can be used on the patient –
The computer will fix it

83. DOSE IMPLICATIONS More exposure to the patient Techniques established
Higher kVp = Less mAs
Less patient dose

84. 80 kvp 200mas
10 mas 80 kvp
Note
Quantum Mottle

85. Dose Implications
Images nearly always look better at higher exposures.
Huge dynamic range means nearly impossible to overexpose.

86. POST PROCESSING
These are all from one exposure.

87. TECHNIQUE CONISDERATIONS
KVP Dependant
Now COMPUTER controls CONTRAST
Higher kVp to stimulate electron traps

88. standard image
edge sharpening
Edge enhancement on the right.

89. REPROCESSED HAND ALGO NO GRID
Skull run on a hand algorithm

90. (replaces film, storage & viewboxes)
QC – Reader (replaces Darkroom & Processor & Chemicals
Diagnostic Viewer
(replaces film, storage & viewboxes)
EXPLAIN EQUIPMENT

91. Magnify the image ot see the fracture better
Magnify the image ot see the fracture better. We can measure what size screws to use.

92. FILM SCREEN PROCESSOR

93. REPEAT IMAGES

94. Post processing probem. Pixels did not align properly in the top image.

95. EMERGING PROBLEMS Better – not necessarily faster
Learning curve for technologists and physicians
Student applications and issues
Pitfalls of CR

97. _____ and proper __________ are critical to good imaging outcomes
Just like Phototiming, it can magnify your mistakes

98. COLLIMATION CRITICAL
As the computer reads the density value of each pixel- it is averaged into the total
Close collimation= Better contrast
Bad collimation= more grays and less detail

100. A B
Collimation open, collimation closed on left.

101. Cannot really do 2 images on one anymore.

105. Digital imaging is not the end all, cure all for imaging problems
It is still technologist dependent
You must continue to think and apply everything learned in Imaging 101.
A computer is not an intelligent machine.
It can only perform as good as the information it was given.

106. To Produce Quality Images
For Conventional Projection
or CR Radiography:
The same rules, theories, and laws still apply and can not be overlooked FFD/OFD (SID/SOD) Inverse Square Law Beam Alignment Tube-Part-Film Alignment Collimation Grids
Exposure Factors: KVP, MaS
Patient Positioning
PATIENT POSITIONING
Accounts for 85% of the total number of repeat exposures.
Has a direct affect on exposure technique.

109. CONVENTIONAL RADIOGRAPHY VIEWING OF “X-RAY FILM” IMAGES
THE DEVELOPED FILM IS THEN REVEIWED FOR IMAGE QUALITY, INFORMATION AND CORRECT POSIITONING OF THE PATIENT.
IF IT IS DETERMINED THAT THE FILM IS OF POOR QUALITY, AND NEEDS TO BE REPEATED – THIS RESULTS IN HAVING TO REPEAT THE ENTIRE PROCESS ALL OVER AGAIN –
REPOISTIONING OF THE PATIENT
, AN ADDITIONAL RADIATION EXPOSURE TO THE PATIENT,
THEN PROCESSING OF THE FILM,
AND RE EVALUATION OF THE IMAGE

110. NEW IMAGE
Towel that was used to help in positioning a child
CR is MORE sensitive to
ARTIFACTS

111. CR image – NEW IMAGE
Line caused from dirt collected in a CR Reader

112. High resolution with digital imaging