Kodak DirectView CR-825, DirectView CR-850 Theory guide
© EASTMAN KODAK COMPANY, 2005 HEALTH GROUP
Confidential
Restricted
Information
{TheoryGuide}{Production}{Health Group}{ExternalAndInternal}
THEORY GUIDE
for the
Kodak DirectView CR 825/850 SYSTEMS
Service Codes: 5634, 4825
Important
Qualified service personnel must repair this equipment.
Publication No. TG4825-1
10DEC05
Supersedes TG4825-1
09JAN04
H177_0500AC
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PLEASE NOTE The information contained herein is based on the experience and knowledge relating to the
subject matter gained by Eastman Kodak Company prior to publication.
No patent license is granted by this information.
Eastman Kodak Company reserves the right to change this information without notice, and
makes no warranty, express or implied, with respect to this information. Kodak shall not be
liable for any loss or damage, including consequential or special damages, resulting from any
use of this information, even if loss or damage is caused by Kodak’s negligence or other fault.
This equipment includes parts and assemblies sensitive to damage from electrostatic
discharge. Use caution to prevent damage during all service procedures.
Table of Contents
Description Page
Equipment Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Features and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Main Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Radiography Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Comparison of Film/Screen and Computed Radiography (CR) . . . . . . . . . . . . 13
Overview of CR Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Exposing the STORAGE PHOSPHOR SCREEN. . . . . . . . . . . . . . . . . . . . . . 17
Stimulating the PHOSPHOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Changing Light Energy to an Analog Signal . . . . . . . . . . . . . . . . . . . . . . . . 20
Changing Analog Signals to Digital Signals . . . . . . . . . . . . . . . . . . . . . . . . 21
Processing the Digital Image. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Sequence of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Overview of Workflow Using the CR 825/850 SYSTEM . . . . . . . . . . . . . . . . . . . 23
Before Loading the CASSETTE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Loading the CASSETTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Fastening the PLATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Preparing to Scan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Scanning the SCREEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Erasing the SCREEN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Inserting the PLATE back into the CASSETTE SHELL . . . . . . . . . . . . . . . . . . . 30
Removing the CASSETTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
STORAGE PHOSPHOR CASSETTE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Size and Resolution of SCREENS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
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Fast Scan / Slow Scan Directions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Image Matrix Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Reading the BAR CODE LABEL of the CASSETTE . . . . . . . . . . . . . . . . . . . . . . 39
Cassette Handling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
DUPLEX CAM AY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Cassette Entry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Cassette Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Plate Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Optical . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
LASER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
GALVO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
COLLECTOR and PHOTOMULTIPLIER TUBE (PMT). . . . . . . . . . . . . . . . . . . . . . 62
Scan/Erase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
PLATE POSITIONING AY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
LEAD SCREW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
EXTRACTION BAR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
REFERENCE SENSOR S9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
PLATE PRESENT SENSOR S5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
SLOW SCAN MOTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
ENCODER. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
ERASE AY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
LAMP CURRENT SENSORS CS1 - CS5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Imaging Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Scanning the SCREEN - Slow Scan/Fast Scan. . . . . . . . . . . . . . . . . . . . . . . . . . 81
Obtaining the Image Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Processing the Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
Processing the Image. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Logic and Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Operator Input Compone nts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
BOARDS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
Distribution of Images to the Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Sequence of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
POWER SUPPLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
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Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
INTERLOCK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
UNINTERRUPTIBLE POWER SUPPLY (UPS). . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Logs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
Error and Activity Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
Error Frequency Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Actuation Log . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
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THEORY GUIDE Equipment Description
Section 1: Equipment Description
Features and Functions
The Kodak DirectView CR 825/850 SYSTEM is a LASER SCANNER that reads a latent
image made on a STORAGE PHOSPHOR SCREEN during an X-ray exam and provides a
digital image. Physicians and radiologists can then view, improve, store and make a print of
the image, and send the image across a computer network.
Size 63.5 x 73.6 cm (25 x 29 in.)
TOUCH SCREEN
MONITOR
• allows the operator to touch areas displayed on the screen to:
– enter exam and patient information
– view and improve images
• allows the FE to do service diagnostics
BAR CODE
READERS
• EXTERNAL BAR CODE READER:
– hand-held READER
– used to scan the BAR CODE LABEL on CASSETTES and
other BAR CODES used for entering data
• INTERNAL BAR CODE READER:
– automatically scans the BAR CODE LABEL on CASSETTES
when they are loaded
– provides information about the size, speed, and serial number
of the CASSETTE
INTERNAL PC • includes software for image processing and for providing
communication with external devices and the computer network
• access is through the front of the CR 825/850 SYSTEM
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THEORY GUIDE Equipment Description
Kodak DirectView
REMOTE
OPERATIONS
PANEL (ROP)
A device that is installed on the wall in an area separate from the CR
825/850 SYSTEM, used for viewing images and entering data. The
ROP includes:
• computer running an INTERNET BROWSER
• TOUCH SCREEN MONITOR - SVGA device with a 600 x 800
pixel resolution
• EXTERNAL BAR CODE READER - can read all formats identified
for the hand-held BAR CODE READER on the CR 825/850
SYSTEM
The ROP allows operators to:
• enter patient, exam, and CASSETTE (PEC) data into a CR 825/
850 SYSTEM
• check patient data
• view scanned X-ray images
• send images to other nodes on the network
PEC data entered through a ROP and sent across the network is
connected with the correct image.
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THEORY GUIDE Equipment Description
Configurations • Standalone - the CR 825/850 SYSTEM is not connected to other
CR 825/850 SYSTEMS:
– can include ROPs
– must have access to an output device for viewing the images
or to obtain a printout
• Cluster - 2 or more CR 850 SYSTEMS are in a network:
– can include up to 10 remote devices, for example Kodak
Directview CR 800/850/900/950 SYSTEMS, ROPs, and
Remote Patient Data Entry Stations (RPDES)
– allows all devices in the network to send infor mation to each
other
– must include one SERVER that stores all patient data
Note
• Devices in a cluster configuration can only send information to
other devices in the same cluster. Devices in one cluster cannot
send information to devices in other clusters.
Network
Communications
• The CR 825 SYSTEM will not operate in a cluster.
All CR 825/850 SYSTEMS and ROP devices:
• connect to the 10 Base-T or 100 Base-T Ethernet network of the
facility
• can send information to all connected DICOM digital imaging
equipment that is qualified with the Medical Image Manager (MIM)
and CR 825/850 SYSTEM
• use CATEGORY 5 CABLES to connect to the network
• use a gateway device qualified by Kodak to enable access to the
HIS/RIS system. The customer must provide this device.
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THEORY GUIDE Equipment Description
On-site Service • CASTERS allow the CR 825/850 SYSTEM to be moved for
service without leveling
• DATA PLATES and MODIFICATION LABELS are located for easy
access and viewing
• PLUGS and CONNECTORS are identified
• data in the Error and Activity logs can be sorted by field for
troubleshooting, for example by date and error code number
• FEs can view internal diagnostics, including error codes,
component tests, and tests of the SENSORS from the TOUCH
SCREEN MONITOR
Remote Service • remote access options:
– dedicated MODEM connected to the CR 825/850 SYSTEM
– MODEM SERVER provided by the customer
• one point of access to the service functions of all CR 825/850
SYSTEMS on the customer network from the remote service
access connection
• access to all service functions, except running the SCAN/ERASE
and Cassette Handling subsystems
• remote service:
– installing software
– setting up the configuration for the CR 825/850 SYSTEM
– retrieving and clearing Error and Activity Logs
– retrieving Image Processing Library (IPL) diagnostic images
Note
FEs providing remote service cannot view the information about the
patient on images.
THEORY GUIDE Equipment Description
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The following tabl e describes the specifications for the number of CASSETTES per hour:
Size CR 825 SYSTEM CR 850 SYSTEM
18 x 24 GP 72 90
24 x 30 GP 62 80
35 x 35 GP 70 90
35 x 43 GP 62 85
18 x 24 HR 70 90
24 x 30 HR 62 80
LONG-LENGTH
60 82
CASSETTE
To ler ance is ± 5
The CR 825 SYSTEM is identical to the CR 850 SYSTEM except the software decreases the
speed.
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THEORY GUIDE Equipment Description
Main Subsystems
CASSETTE
SHELL
CASSETTE
PLATE
TOUCH
SCREEN
MONITOR
Error and Activity
Cassette Entry/
Cassette Transport
Logs
Cassette
Handling
DUPLEX
CAM AY
EXTERNAL
BAR CODE
READER
INTERNAL
PC
LOGS
INTERNAL
BAR CODE
READER
ERASE
LAMPS
to
network
Ethernet
CARDS
A1
MSC
BOARD
A6
SLOW SCAN
CONTROLLER BOARD
SLOW SCAN
ENCODER
SLOW SCAN
A2
MCPU
BOARD
A3
DIGITIZER
BOARD
A5
PMT/DAS
BOARD
Scan/Erase
MOTOR
CR 850 SYSTEM
PMTs
GALVO
Imaging
COLLECTOR
Logic and Control
Optical
A4
GALVO
BOARD
A18
LASER
DRIVER
PRE-
REGULATOR
BOARD
A17
LASER DIODE
DRIVER BOARD
LASER
SCREEN
AC power
90 - 264 V AC
H194_5044DC
Plate
Handling
T1
TRANSFORMER
K1 RELAY
UPS
Power Distribution
PS1
POWER
SUPPLY
DC power to
all BOARDS
and MOTORS
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THEORY GUIDE Equipment Description
Subsystem Description See:
CASSETTE • includes:
– STORAGE PHOSPHOR
SCREEN that captures and stores the X-
STORAGE
PHOSPHOR
CASSETTE
ray image for processing
– CASSETTE SHELL that holds the PLATE
• available in 5 sizes and 3 resolutions (GP,
HR, and EHR)
Cassette Handling • loads the CASSETTE into the CR 825/850
SYSTEM
• removes the PLATE from the CASSETTE
SHELL
• after scanning, installs the PLATE in the
CASSETTE SHELL
• allows the CASSETTE to be removed from
the CR 825/850 SYSTEM
Optical • controls and moves the laser beam to the
SCREEN
• captures the blue light emitted from the
SCREEN
Scan/Erase • moves the PLATE at a uniform speed:
– through the scanning area
– to the erase position
• removes the residual image on the SCREEN
by exposing it to intense light
Cassette Handling
Optical
Scan/Erase
• inserts the PLATE into the CASSETTE
SHELL again
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THEORY GUIDE Equipment Description
Subsystem Description See:
Imaging • assembles the data from the screen and
Imaging Sequence
changes it to digital format
• processes the image
Logic and Control • processes commands from the operator
• controls the operation of all subsystems
• sends processed images to the network for
distribution
Pow e r D i s t r ib u ti o n • provides power for all subsystems
• includes an UNINTERRUPTIBLE POWER
SUPPLY (UPS)
• has an INTERLOCK SWITCH that actuates
when the FRONT DOOR is opened
Error and Activity
Logs
• records logs of errors in the system
• records user actions
Logic and Control
Power Distribution
Logs
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THEORY GUIDE Radiography Theory
Section 2: Radiography Theory
Comparison of Film/Screen and Computed Radiography (CR)
FILM/
X-RAY latent image
TUBE
(On Film)
FILM PROCESSING
visible image
(On Film)
SCREEN
AERIAL
IMAGE
FINAL VISIBLE
IMAGE
(Film or Viewer)
STORAGE
X-RAY
TUBE
(Storage Phosphor)
CONVERSIONS
visible imagelatent image
(CRT)
ENHANCED
PROCESSING
PHOSPHOR
SCREEN
X-rays are used in medical imaging to make an image of given body parts on a surface,
which can be read by a Radiologist or other medical personnel. The available systems for
capturing these images are:
• Screen/film - captures a projection image on an X-ray film
• Computed Radiography (CR) - captures a digital image
THEORY GUIDE Radiography Theory
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The following phases are necessary to capture and process projection radiographs for both
screen/film systems and CR systems:
Phase of Image Capture Description
Phase 1 Making the aerial image
In both screen/film and CR systems:
• an X-ray TUBE emits X-rays in the direction of an IMAGE
RECEPTOR
• when the X-rays reach the body of the patient, some are
absorbed by the patient and some are not. The result is an
“aerial” image with varying degrees of X-ray power (varying
numbers of X-ray photons)
Phase 2 Capturing the latent image
When the IMAGE RECEPTOR is exposed to the X-rays in the
aerial image, a latent image is captured on the RECEPTOR:
• screen/film systems - image is captured on sensitized
radiographic film
• CR systems - image is captured on a STORAGE
PHOSPHOR SCREEN. The X-ray photons that reach the
SCREEN charge the PHOSPHOR, making a latent image
on the screen.
Phase 3 Capturing, changing, and
storing the visible image
The latent image must be changed to a visible image, which
can be read by the Radiologist, moved from one place to
another, and stored for use at another time:
• screen/film systems - radiographic film is processed through
chemicals and the latent image is fixed onto the film
• CR systems - the latent image on the STORAGE
PHOSPHOR SCREEN is scanned by a laser beam, which
stimulates the charged PHOSPHOR on the SCREEN. Blue
light is emitted from the stimulated PHOSPHOR, assembled,
and changed into analog electrical signals. The analog
image is then changed into digital signals and processed.
The digital image is stored and displayed by a computer
system and can be routed to other computers and
PRINTERS through a network.
THEORY GUIDE Radiography Theory
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The following tabl e compares the analog and digital health image capture systems.
Analog Screen/Film Systems Digital CR Systems
Uses “Rare Earth” SCREENS GADOLINIUM OXYSULFIDE or
Uses a BARIUM FLOUROHALIDE STORAGE
PHOSPHOR SCREEN.
LANTHANUM OXYBROMIDE.
Speed range from 100 - 1000. Screen speed:
• General Purpose (GP), 200 - 250
• High Resolution (HP), 100 - 125
• Enhanced High Resolution (EHR), 100 - 125
Film processing parameters are important
No film processing is necessary.
in determining the quality of the image,
for example chemical temperature and
timing.
It is hard to obtain the same print quality
when copies are necessary because of
The user can print a copy of the digital image
at any time.
variations in GENERATORS,
PROCESSORS, positions, procedures,
and conditions for developing the film.
Overexposing or underexposing an image
normally makes it necessary to expose
the patient to ionizing radiation again.
Image quality is changed by conditions in
the environment, for example temperature
or humidity.
The image cannot be viewed in more
than one place at a time.
Exposure factors do not normally make it
necessary to expose the patient to ionizing
radiation again.
Image quality is not changed by conditions in
the environment.
CR images can be viewed at more than one
place at the same time, in the same building or
in remote nodes on the network.
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THEORY GUIDE Radiography Theory
Analog Screen/Film Systems Digital CR Systems
• Recording medium - film
• Output medium - film
• Storing medium - film
• Recording medium - STORAGE
PHOSPHOR SCREEN
• Output medium - film, paper, digital display
• Storing medium - digital
Image density and contrast are controlled
by kilovolts peak (kvP), milliampere
seconds (mA.s), and film type.
Viewing quality can only be improved by
increasing the brightness of the LAMP
that illuminates the film.
The quality of films that are not exposed
correctly cannot be improved.
Density and contrast are controlled by image
processing parameters. kvP, and mA.s continue
to be important image control factors for details
and noise in the digital image.
Digital images can be improved by processing
on a computer to change the density, contrast,
sharpness, and other factors.
Images that were not exposed correctly can be
improved. For example, software parameters
can improve image density and contrast.
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THEORY GUIDE Radiography Theory
Overview of CR Technology
Operations
The following operations are necessary to capture the latent image in the STORAGE
PHOSPHOR SCREEN and change it to a digital image that can be viewed on a computer
screen and sent to a PRINTER.
• Exposing the STORAGE PHOSPHOR SCREEN
• Stimulating the PHOSPHOR
• Changing Light Energy to an Analog Signal
• Changing Analog Signals to Digital Signals
• Processing the Digital Image
Exposing the STORAGE PHOSPHOR SCREEN
X-RAY
TUBE
H194_5033BC
aerial
image
STORAGE PHOSPHOR SCREEN
Charged storage phosphors
proportional to X-ray energy
absorbed by screen.
latent
image
Lighter values indicate that more
x-rays were absorbed by the
SCREEN - bone tissue
Mid-range values indicate that fewer
x-rays were absorbed by the
SCREEN - soft tissue
Darker values indicate that most
x-rays were absorbed by the
SCREEN - did not pass through the body
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When a STORAG E PHOSPHOR SCREEN is exposed to X-rays:
• special PHOSPHOR on the SCREEN absorbs the radiation in degrees of intensity
determined the body par t and the type of SCREEN:
– soft body tissues absorb a small quantity of radiation - these areas are indicated in the
X-ray image by mid-range values
– bone tissues absorb most of the radiation - these areas are indicated in the X-ray
image by light values
– X-rays that do not hit any obstructions are indicated in the X-ray image by dark values
– High Resolution SCREENS absorb less energy than General Purpose SCREENS
• SCREEN has a latent image in the areas that were exposed to the radiation. The quantity
of stored energy or charge on the SCREEN is proportional to the quantity of
X-ray energy absorbed by the SCREEN.
Characteristics of the
STORAGE P HOSPHOR
SCREEN
Description
X-ray absorption About 50% of the X-ray energy is released in the form of
fluorescence when the SCREEN is exposed. The X-ray energy
remaining makes the latent image on the SCREEN.
Photostimulable
luminescence
When the charged PHOSPHOR on the SCREEN is stimulated by
light, the PHOSPHOR releases or discharges blue light proportional
to the energy the PHOSPHOR has stored.
Fading The latent image fades with time, but it is possible to read data from
the SCREEN for a number of days after scanning.
Residual image After a SCREEN is erased by exposing it to light, it keeps some
charge from the latent image. This charge does not make the
SCREEN less effective when it is used again.
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THEORY GUIDE Radiography Theory
Characteristics of the
STORAGE P HOSPHOR
SCREEN
Description
Signal accumulation Signals can accumulate on SCREENS that are not used for more
than 24 hours. Erasing these SCREENS decreases the residual
image to the optimum range for using the SCREEN again. Failure to
erase these signals can result in artifacts.
Long life The photostimulable luminescent quality of the SCREEN does not
decrease with time. The life of a SCREEN can be decreased by
damage to the material.
Stimulating the PHOSPHOR
It is necessary to stimulate the PHOSPHOR in the SCREEN to read the latent image. The
following components of the CR systems provide this function:
• light source:
– exposes the SCREEN with high-intensity light that stimulates the electrons and causes
the electrons to be luminescent
– laser beam moves from one side of the SCREEN to the other to ex pose the image
• DEFLECTOR:
– moves the laser beam across the SCREEN and then back to the starting position. At
the same time, the SCREEN moves perpendicular to the scanning direction of the
laser beam.
– is continually monitored and adjusted to check that the scanning operation is correct
and has a continual speed
• scanning optics:
– focuses and shapes the laser beam, keeping the speed and angle of the beam the
same when it moves across the SCREEN
– angle of a laser beam determines the size, shape, and speed of the beam. An
example is the beam of a flashlight moving across a flat surface from one edge to the
center and to the other edge.
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Changing Light Energy to an Analog Signal
The following components of CR systems change the light energy in the exposed SCREEN to
an analog signal:
• LIGHT COLLECTOR:
– provides the collection of the blue light emitted when the SCREEN is stimulated by the
laser beam
– CR 825/850 SYSTEM uses an INTEGRATING CAVITY with MIRRORS to provide the
collection of the blue light
• BLUE FILTER:
– does not allow any red light reflected from the SCREEN to reach the LIGHT
DETECTORS
– allows only the blue light to reach the LIGHT DETECTORS
• LIGHT DETECTORS:
– are normally PHOTOMULTIPLIER TUBES (PMT)
– receive light that enters the COLLECTOR
– change the light photons into electrons when the photons enter through a
PHOTOCATHODE. When the electrons move through the LIGHT DETECTORS, the
electrons increase in number - “gain”.
– when more than one LIGHT DETECTOR is used in a system, the system adds and
changes the signals into one output. The output from the added PMTs can include
frequencies that are outside of the limits of the system - “noise”. An ANALOG FILTER
limits this noise.
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Changing Analog Signals to Digital Signals
SAMPLING
Y
image
sample
grid
X
analog image digital image
(continual values) (discrete values)
pixel code value
(0 - 4095)
image
matrix
H194_5014HC
Analog signals are changed to digital signals by sampling the blue light from the STORAGE
PHOSPHOR SCREEN and moving it through an ANALOG-TO-DIGITAL CONVERTER to
make a digital value for the br ightness of each sample.
Sampling is similar to making a photograph of the signal at a given time. The sample has
both a horizontal and a vertical value. The size of the sample is defined in the system
software for both the horizontal and ver tical directions.
• The horizontal value indicates a point in time in the motion of the laser beam across the
SCREEN.
• The vertical value indicates a line on the screen at a right angle to the scanning direction.
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If you find both the horizontal and the vertical points of the sample on an imaginary matrix,
similar to the one in the graphic, the result indicates one pixel in the digital image.
Continual analog input values are changed to output values. In this process, the replacement
of small ranges of analog input values with one digital output value occurs. The digital output
value indicates one pixel of infor mation on the TOUCH SCREEN MONITOR.
The output is a linear digital signal. The CR 825/850 SYSTEM emits a 16-bit digital signal
with a total signal range of 65,536 levels. Because it is not possible for the human eye to see
this range of separate values, the CR 825/850 SYSTEM changes the 16-bit linear image data
to 12-bit log data. This 12-bit log provides data from 0 - 4095 values. These values are used
in the CR 825/850 SYSTEM.
Processing the Digital Image
Digital imaging allows users to improve diagnostic images by processing the images. After the
digital image is made, the digital data is processed using parameters set up in the software.
In the CR 825/850 SYSTEM, this processing occurs in the INTERNAL PC.
Examples of image processing used for digital images:
• segmentation
• tone scaling
• edge enhancement
• brightness - level
• contrast - window
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THEORY GUIDE Sequence of Operation
Section 3: Sequence of Operation
Overview of Workflow Using the CR 825/850 SYSTEM
1 The Radiology Department receives an exam request.
2 The Radiologist, the operator, assembles the patient information. Examples of patient
information are patient name, ID, and accession number.
Note
If the facility has a Hospital Information System/Radiographic Information System (HIS/RIS)
that is HL-7 compatible, the patient infor mation can be automatically downloaded to the
CR 825/850 SYSTEM through a HIS/RIS gateway. If no automatic connection is available, the
information can be manually entered at a ROP or a CR 825/850 SYSTEM.
3 The operator can select network nodes to send the image data to.
4 The operator uses a CR CASSETTE to do the exam, capturing the latent image on the
STORAGE PHOSPHOR SCREEN.
5 Using the CR 825/850 SYSTEM or the ROP, the operator enters the CASSETTE ID
Information by scanning the CASSETTE BAR CODE or entering it manually.
6 The operator inserts the exposed CASSETTE into the CR 825/850 SYSTEM. The system
scans the SCREEN, capturing the latent image on the SCREEN and changing it to a
digital image. After scanning, the SCREEN is automatically erased and inserted into the
CASSETTE SHELL.
7 The CR 825/850 SYSTEM processes the image. If the system is in:
• Pass-Through Mode - the image is automatically sent to all network nodes
• QA Mode - the operator can process the image and then send it to other network
nodes
8 If necessary, the image can be processed and sent to networ k nodes again.
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Before Loading the CASSETTE
1 After initializing, the CR 825/850 SYSTEM is ready to receive a CASSETTE for scanning.
2 The Radiology Technologist uses a Computed Radiology (CR) CASSETTE to capture the
latent image of the body part on the SCREEN.
Status Summary: Ready to Receive a CASSETTE
• DUPLEX CAM is at the home position 1
• DRIVE ROLLERS and IDLER ROLLERS are in contact with the
CASSETTE
• PIVOTING PLUSH is in the open position
• LIGHT SEAL BAR is in the open position
• CASSETTE DRIVE MOTOR is stopped
• EXTRACTION BAR is at the home position
Loading the CASSETTE
1 The operator loads the CASSETTE into the INPUT SLOT until the CASSETTE reaches
the CASSETTE ENTRY SENSOR S1.
2 The CASSETTE ENTRY SENSOR S1 detects the CASSETTE.
Note
The MSC BOARD continually monitors the CASSETTE LOAD SENSOR S2. At the S2
SENSOR, the system must detect a CASSETTE within 5 seconds or an error message
displays.
3 The INTERNAL BAR CODE READER reads the size, speed, and serial number of the
CASSETTE, then:
• emits a sound
• sends information to the MCPU BOARD A2:
– “CASSETTE Detected” message
– size of the CASSETTE
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4 The MCPU BOARD A2 sends:
• “CASSETTE Detected” message to the MSC BOARD A1
• “Scan Request” message to the INTERNAL PC
5 The INTERNAL PC:
• checks that it has the quantity of memory necessary to receive an image
• makes a raw image file to receive the image
• sends a “Scan Request Reply” message to the MCPU BOARD A2 with a value of
“OK”
6 The MCPU BOARD A2:
• sends a message to the MSC BOARD A1 to load the CASSETTE
• sends the information about the size and speed of the CASSETTE to the DIGITIZER
BOARD
Note
If the BAR CODE readout is not successful, the operator must enter the data manually. When
BAR CODE data is entered manually, the data is provided by the INTERNAL PC and not the
BAR CODE READER.
7 The CASSETTE DRIVE MOTOR M2 actuates. The MOTOR drives the TIMING BELTS,
which rotate the DRIVE ROLLERS.
8 The DRIVE ROLLERS drive the CASSETTE to the back until the CASSETTE REAR
SENSOR S3 detects the CASSETTE.
9 The CASSETTE REAR SENSOR S3 sends a signal to the MSC BOARD A1 to
deactuate the MOTOR.
10 After a delay of 20 ms, the MSC BOARD A1 deactuates the MOTOR.
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THEORY GUIDE Sequence of Operation
Status Summary: CASSETTE Loaded
• DUPLEX CAM is in the home position
• DRIVE/IDLER ROLLERS are engaged on the CASSETTE
• CASSETTE is at the CASSETTE REAR STOP and the CLAMP
BARS are open
• CASSETTE DRIVE MOTOR M2 is stopped
• PLATE remains inside the CASSETTE
• HOOKS on the EXTRACTION BAR are not extended
Fastening the PLATE
1 The DUPLEX CAM moves from position 1 directly to position 3. See “DUPLEX CAM
AY.”
2 When the CAM rotates, the SLED CAM and the HOOK CAM execute the following
actions. The first degrees of the CAM rotation move the HOOKS up. The remaining part
of the rotation releases the LATCHES of the CASSETTE and fastens the PLATE to the
EXTRACTION BAR.
• SLED CAM actions:
– SLED PLATE moves 1.5240 cm (0.600 in.) forward
– PIVOTING PLUSH rotates to make a light-tight environment around the
CASSETTE
• HOOK CAM actions:
– HOOK CAM moves against the HOOK YOKE FOLLOWER, which starts the
mechanical sequence to extend the HOOKS on the EXTRACTION BAR into the
LATCH AY. See “Plate Handling.”
– With the HOOKS in position inside the CASSETTE, the forward motion of the
SLED causes the SPRING-LOADED LATCH inside the PLATE to release and
fastens the PLATE to the EXTRACTION BAR.
3 The MSC BOARD A1 sends a signal to the MCPU BOARD that the CASSETTE is
loaded.
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THEORY GUIDE Sequence of Operation
Status Summary: PLATE Fastened
• DUPLEX CAM has reached position 3
• SLED is 1.524 cm (0.600 in.) forward from the home position
• CLAMP BARS are holding the CASSETTE
• PLATE is fastened to the EXTRACTION BAR
• EXTRACTION BAR is at home position with the fastened
PLATE
• PIVOTING PLUSH has made a light-tight environment
around the CASSETTE
• DUPLEX CAM MOTOR M1 is de-energized
Preparing to Scan
1 The SLOW SCAN MOTOR starts rotating the LEAD SCREW, pulling the PLAT E down
from the CASSETTE.
• When the EXTRACTION BAR moves down to the position immediately before
scanning starts, the LOWER ARM of the PLATE POSITIONING AY moves forward to
touch the back of the PLATE, which is partially out of the CASSETTE SHELL. The
LOWER ARM keeps the PLATE from touching the WALLS of the CASSETTE when it
moves out of the CASSETTE.
• After the LOWER ARM moves forward to touch the back of the PLATE, the UPPER
ARM of the PLATE POSITIONING AY also moves forward. It keeps the larger PLAT E
steady during scanning and when they leave and move back into the CASSETTE.
2 When the PLATE is moving into the start of scan position, the MCPU BOARD A2
energizes the PMTs and sets the SIGNAL CHANNEL for the PMTs to 0.
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3 The PLATE PRESENT SENSOR S5 detects that a PLATE is fastened and sends a
message of the status to the MSC BOARD A1.
Status Summary: Prepared for Scanning
• PMTs are energized
• SIGNAL CHANNEL is set to 0
Scanning the SCREEN
1 The MCPU BOARD A2:
• actuates the GALVO
• sends a signal to the MSC BOARD A1 to start the scan, which star ts the SLOW
SCAN MOTOR
• sends a signal to the INTERNAL PC that the scan is starting
2 The INTERNAL PC displays a TIMED PROGRESS BAR on the TO UCH SCREEN
MONITOR. This is a graphic display only and not a real-time indication of the status of
the scanning operation.
3 The SLOW SCAN MOTOR rotates, moving the SCREEN at a continual speed through
the field of scan in the slow scan direction.
4 The GALVO BOARD A4 controls the motion of the laser beam across the SCREEN in
the fast scan direction. The SCREEN is scanned one pixel at a time, one line at a time.
See “Scanning the SCREEN - Slow Scan/Fast Scan.”
Note
• The fast scan motion is an almost horizontal trace across the SCREEN, from the back of
the SCREEN toward the front. When it reaches the end of a line, it does a fast retrace to
start another line. During the scanning, the SCREEN is moving down at a controlled
speed to make each fast scan trace one pixel line higher up on the SCREEN than the line
before. The result is that the fast scan is in a slightly diagonal trace across the SCREEN.
• The slow scan runs for a determined number of lines in the vertical direction. A set
number of samplings occur for each line. The number is determined by the size of the
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SCREEN. Both the number of lines and the number of samplings are set up in the
calibration for that size of SCREEN.
5 When the end of the scan is reached, the MSC BOARD A1 sends a status message to
the MCPU BOARD A2.
6 The MCPU BOARD A2 de-energizes the PMTs, GALVO, and the LASER.
7 The MCPU BOARD A2 sends a “Scan End” message to the INTERNAL PC. The TIMED
PROGRESS BAR displays until the image is transferred to the INTERNAL PC.
Erasing the SCREEN
1 The MCPU BOARD A2 sends an “Erase Plate” command to the MSC BOARD, which
sends a signal to the SLOW SCAN to start the erasing operation.
2 The SLOW SCAN MOTOR actuates and moves the SCREEN into the erase position,
determined by the counts of the SLOW SCAN ENCODER.
3 The SLOW SCAN MOTOR stops and waits for a response from the MCPU BOARD A2.
4 The MCPU BOARD A2 sends the “Erase” command and time to the MSC BOARD A1,
which actuates the ERASE LAMPS.
5 The ERASE LAMPS illuminate for 2 - 16 seconds to remove the image from the
SCREEN.
Note
The length of time the ERASE LAMPS illuminate is determined by the highest pixel code
value of the image that was scanned. If one pair of LAMPS is not operating, the time
increases by a factor of 2. If more than one pair of LAMPS is not operating, a message
displays on the TOUCH SCREEN MONITOR.
6 When the SCREEN is erased, the MSC BOARD A1 sends the “Erase Done” status to
the MCPU BOARD A2.
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Inserting the PLATE back into the CASSETTE SHELL
1 The MCPU BOARD A2 issues a command to the MSC BOARD A1 to:
• return the EXTRACTION BAR to the home position
• insert the SCREEN into the CASSETTE
2 The MSC BOARD A1 reverses the SLOW SCAN MOTOR, which moves the PLATE up
into the open CASSETTE SHELL.
3 The PLATE POSITIONING AY guides the PLATE into the CASSETTE SHELL from the
back side.
4 When the EXTRACTION BAR reaches the home position, the SLOW SCAN MOTOR
stops. At the home position, the ENCODER counts are the saved value.
Status Summary: SCREEN Inserted Into the CASSETTE
• SLOW SCAN MOTOR is stopped
• SCREEN is inside the CASSETTE
• HOOKS are inside the SCREEN
Removing the CASSETTE
1 The MCPU BOARD A2 sends an “Eject Cassette” command to the MSC BOARD A1.
2 The CAM MOTOR M1 energizes.
3 The DUPLEX CAM moves toward position 4. See “DUPLEX CAM AY.”
4 When the DUPLEX CAM rotates, the SLED CAM and the HOOK CAM execute the
following actions:
• SLED CAM:
– SLED PLATE moves toward the back 0.896 cm (0.350 in.)
– PIVOTING PLUSH opens
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