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Dawn Guzman Charman, M.Ed., R.T. RAD TECH A

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1 Dawn Guzman Charman, M.Ed., R.T. RAD TECH A
COMPUTED RADIOGRAPHY Dawn Guzman Charman, M.Ed., R.T. RAD TECH A Good Morning My Presentation to you today is the process , procedure and the reason that I undertook the task to develop a CURRICULUM GUIDE TO TEACH COMPUTED RADIOGRAPHY My

2 filmless’ radiology departments
Diagnostic radiographers have traded their film and chemistry for a computer mouse and monitor 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

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5 New Technology Has impacted 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

6 Many local area hospitals
and medical centers have this equipment NOW

7 Computed Radiography Fundamentals of Computerized Radiography

8 CR SYSTEM COMPONENTS CASSETTES (phosphor plates) ID STATION
IMAGE PREVIEW (QC) STATION DIGITIZER VIEWING STATION

9 Medical Imaging is changing
COMPUTED RADIOGRAPHY Medical Imaging is changing “FILMLESS” Radiology is the future And the Future is here! El Camino College First educational institution in California or across the country to offer this new technology on a college campus COMPUTED RADIOGRAPHY IS HERE READ SLIDE Now RT’s must further refine who they are and what they will contribute in the context of rapidly changing health care needs

10 Equipment Costs Don Visintainer successfully wrote grants, and received funding from VTEA, P4E, and private sources The Carl D. Perkins Vocational and Technical Education Act (VTEA) of 1991 was instrumental in helping to provide funds needed to purchase this equipment for an on-campus laboratory State of California, Performance for Excellence (P4E), and private funding were also key Total $410, HIDDEN COSTS *

11 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

12 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

13 History of CR By 1998 – over 5000 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

14 TERMINOLOGY F/S - Film/Screen (currently used method)
CR Computed Radiography DR Digital Radiography DDR - Direct to Digital Radiography

15 IMAGE CREATION SAME RADIOGRAPHY EQUIPMENT USED
THE DIFFERENCE IS HOW IT IS CAPTURED STORED VIEWED And POST -PROCESSED

16 CONVENTIAL vs DIGITAL IMAGING
Currently, most x-ray imaging systems produce an analog image (radiographs, & fluoroscopy). Using x-ray tube – films in cassettes

17 CONVENTIAL vs DIGITAL IMAGING
Digital radiography systems require that the electronic signal be converted to a digital signal – Using x-ray tube – cassettes with phosphor plate OR DR systems - transistors

18 COMPUTED RADIOGRAPHY & DIRECT RADIOGRAPHY & FILM SCREEN IMAGE CAPTURE
FS - Film inside of cassette CR - PHOTOSTIMULABLE PHOSPHOR PLATE DR(DDR) - TFT (THIN FILM TRANSISTOR)

19 Cassette w/ film CR w psp plate

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21 Directed Digital Radiography (DDR)
Directed digital radiography, a term used to describe total electronic imaging capturing. Eliminates the need for an image plate altogether.

22 Amorphous Selenium detector technology for
DR Direct Radiography

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24 IMAGE CAPTURE CR DR – NO CASSETTE – PHOTONS
PSP – photostimulable phosphor plate REPLACES FILM IN THE CASSETTE DR – NO CASSETTE – PHOTONS CAPTURED DIRECTLY ONTO A TRANSISTOR SENT DIRECTLY TO A MONITOR

25 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

26 CASSETTES with Intensifying Screens
The CASSETTE holds the film in a light tight container It consist of front and back intensifying screens

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

31 CR – PSP plate Stimulated by a RED LIGHT
Energy is RELEASED in a form of BLUE light LIGHT captured by PMT – changed to a digiial signal

32 How CR works Released light is captured by a PMT (photo multiplier tube) This light is sent as a digital signal to the computer The intensity (brightness) of the light – correlates to the density on the image

33 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

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35 ERASING PLATE After image is recorded
Plate is erased with high intensity white light and re-used

36 CR VS DR CR -Indirect capture where the image is first captured on plate and stored = then converted to digital signal DDR -Direct capture where the image is acquired immediately as a matrix of pixels – sent to a monitor

37 DIRECT RADIOGRAPHY uses a transistor receiver (like bucky)
that captures and converts x-ray energy directly into digital signal seen immediately on monitor then sent to PACS/ printer/ other workstations FOR VIEWING

38 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 –

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40 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)

41 ADVANTAGE OF CR/DR Can optimize image quality
by manipulating digital data to improve visualization of anatomy and pathology AFTER EXPOSURE TO PATIENT

42 ADVANTAGE OF CR/DR AFTER THE EXPOSURE
CHANGES MADE TO IMAGE AFTER THE EXPOSURE CAN ELIMINATE THE NEED TO REPEAT THE EXPOSURE

43 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?

44 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

45 “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

46 DR Initial expense high very low dose to pt –
image quality of 100s using a 400s technique Therfore ÂĽ the dose needed to make the image

47 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

48 Transmission of Images
PACS - Picture Archiving & Communications System DICOM - Digital Images & Communication in Medicine TELERADIOGRAPHY -Remote Transmission of Images

49 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

50 “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”.

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

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53 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

54 Adapted from AAPM TG10

55 Statistical plots of the frequency of occurrence of each pixel's value

56 Basics of Digital Images
digital images are a (matrix) of pixel (picture element) values

57

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

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

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61 Methods to Digitize an Image
1. Film Digitizer - Teleradiography system (PACS, DICOM) 2. Video Camera (vidicon or plumbicon) 3. Computed Radiography 4. Direct Radiography

62 FILM DIGITIZER

63 Analog vs Digital Analog - one value blends into another
(like a thermometer) Digital - distinct separation 98.6 exact

64 ANALOG TO DIGITAL IMAGE
Conversion of conventional analog films to digital format for PACs and teleradiology applications with scanning laser digitizers

65 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

66 High displayed contrast – narrow window width

67 Low displayed contrast (stretched) – wide window width

68 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

69 80 KVP 5 30 5 15 100 200 500

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

71 DOSE IMPLICATIONS MORE EXPSOURE TO PATIENT TECHNIQUES ESTABLISHED
HIGHER KVP = LESS MAS LESS PATIENT DOSE

72 80 kvp 200mas 10 mas 80 kvp Note Quantum Mottle

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

74 POST PROCESSING

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

76 standard image edge sharpening

77

78

79 DEVELOPER FIXER WASH DRY WATER - SOLVENT

80 PROCESSOR PROBLEM – FIXER RETENTION

81 scratch

82 Crimping /cresent mark

83 REPEAT IMAGES

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85 EMERGING PROBLEMS “BETTER” –NOT NECESSARILY FASTER
“LEARNING CURVE” FOR TECHNOLOGIST & PHYSICIANS STUDENT APPLICATIONS & “ISSUES” “PITFALLS OF CR”

86 POSITIONING & PROPER COLLIMATION ARE CRITICAL TO GOOD IMAGING OUTCOMES
Just like Phototiming, it can magnify your mistakes

87 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

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89 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.

90 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.

91 NEW IMAGE towel that was used to help in positioning a child CR is MORE sensitive to ARTIFACTS

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

93 Double exposure Child

94 ? Hands over upper abdomen

95 High resolution with digital imaging


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