Kodak DirectView CR-825, DirectView CR-850 Theory guide

© EASTMAN KODAK COMPANY, 2005	HEALTH GROUP
	Publication No. TG4825-1
	10DEC05
	Supersedes TG4825-1
	09JAN04
Confidential
Restricted
Information

THEORY GUIDE for the

Kodak DirectView CR 825/850 SYSTEMS

Service Codes: 5634, 4825

Important

Qualified service personnel must repair this equipment.

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 Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	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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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	• allows the operator to touch areas displayed on the screen to:
MONITOR	– enter exam and patient information
	– view and improve images
	• allows the FE to do service diagnostics
BAR CODE	• EXTERNAL BAR CODE READER:
READERS	– 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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Kodak DirectView	A device that is installed on the wall in an area separate from the CR
REMOTE	825/850 SYSTEM, used for viewing images and entering data. The
OPERATIONS	ROP includes:
PANEL (ROP)	• 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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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 information 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.
			•	The CR 825 SYSTEM will not operate in a cluster.
Network		All CR 825/850 SYSTEMS and ROP devices:
Communications			•	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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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.

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The following table 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
	Tolerance is ± 5

The CR 825 SYSTEM is identical to the CR 850 SYSTEM except the software decreases the speed.

	THEORY GUIDE							Equipment Description
10DEC05	Main Subsystems
TG4825-1
Page
10 of 120		TOUCH	EXTERNAL
		SCREEN	BAR CODE		to
		MONITOR	READER		network	CR 850 SYSTEM
								Logic and Control
				INTERNAL			Imaging
						A2
				PC
						MCPU
		Error and Activity			Ethernet	BOARD		Optical
				LOGS
					CARDS
		Logs
						A3		A4
						DIGITIZER		GALVO
						BOARD		BOARD
				INTERNAL	A1		PMTs
				BAR CODE
					MSC
				READER
					BOARD	A5	COLLECTOR
								A18
						PMT/DAS
								LASER
						BOARD
								DRIVER
								PRE-
		Cassette						REGULATOR
						Scan/Erase		BOARD
		Handling
					A6		GALVO
		DUPLEX			SLOW SCAN
					CONTROLLER BOARD
		CAM AY						A17
	CASSETTE							LASER DIODE
								DRIVER BOARD
	SHELL			ERASE	SLOW SCAN	SLOW SCAN
		Cassette Entry/
	CASSETTE			LAMPS	ENCODER	MOTOR		LASER
		Cassette Transport
	PLATE
	SCREEN
		Plate
		Handling
					K1 RELAY		Power Distribution
								DC power to
								all BOARDS
							PS1	and MOTORS
	AC power
				T1			POWER
						UPS
	90 - 264 V AC			TRANSFORMER			SUPPLY
	H194_5044DC

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Subsystem		Description	See:
CASSETTE	• includes:		STORAGE
		– STORAGE PHOSPHOR	PHOSPHOR
			CASSETTE
		SCREEN that captures and stores the X-
		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		Cassette Handling
		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		Optical
		SCREEN
	•	captures the blue light emitted from the
		SCREEN
Scan/Erase	• moves the PLATE at a uniform speed:		Scan/Erase
		– through the scanning area
		– to the erase position
	• removes the residual image on the SCREEN
		by exposing it to intense light
	• inserts the PLATE into the CASSETTE
		SHELL again

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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		Logic and Control
	•	controls the operation of all subsystems
	•	sends processed images to the network for
		distribution
Power Distribution	• provides power for all subsystems		Power Distribution
	• includes an UNINTERRUPTIBLE POWER
		SUPPLY (UPS)
	• has an INTERLOCK SWITCH that actuates
		when the FRONT DOOR is opened
Error and Activity	• records logs of errors in the system		Logs
Logs	•	records user actions

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Section 2: Radiography Theory

Comparison of Film/Screen and Computed Radiography (CR)

X-RAY	latent image	visible image
TUBE	(On Film)	(On Film)
FILM/		FILM PROCESSING

SCREEN

AERIAL

IMAGE

	latent image	visible image	FINAL VISIBLE
X-RAY			IMAGE
TUBE	(Storage Phosphor)	(CRT)	(Film or Viewer)
STORAGE			ENHANCED
	CONVERSIONS		PROCESSING
PHOSPHOR
SCREEN
	AERIAL

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

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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 -	In both screen/film and CR systems:
Making the aerial image	•	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 -	When the IMAGE RECEPTOR is exposed to the X-rays in the
Capturing the latent image	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 -	The latent image must be changed to a visible image, which
Capturing, changing, and	can be read by the Radiologist, moved from one place to
storing the visible image	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.

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The following table compares the analog and digital health image capture systems.

Analog Screen/Film Systems		Digital CR Systems
Uses “Rare Earth” SCREENS -	Uses a BARIUM FLOUROHALIDE STORAGE
GADOLINIUM OXYSULFIDE or	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	The user can print a copy of the digital image
when copies are necessary because of	at any time.
variations in GENERATORS,
PROCESSORS, positions, procedures,
and conditions for developing the film.
Overexposing or underexposing an image	Exposure factors do not normally make it
normally makes it necessary to expose	necessary to expose the patient to ionizing
the patient to ionizing radiation again.	radiation again.
Image quality is changed by conditions in	Image quality is not changed by conditions in
the environment, for example temperature	the environment.
or humidity.
The image cannot be viewed in more	CR images can be viewed at more than one
than one place at a time.	place at the same time, in the same building or
	in remote nodes on the network.

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		Analog Screen/Film Systems	Digital CR Systems
	•	Recording medium - film	• Recording medium - STORAGE
	•	Output medium - film	PHOSPHOR SCREEN
			• Output medium - film, paper, digital display
	•	Storing medium - film
			• Storing medium - digital
	Image density and contrast are controlled		Density and contrast are controlled by image
	by kilovolts peak (kvP), milliampere		processing parameters. kvP, and mA.s continue
	seconds (mA.s), and film type.		to be important image control factors for details
			and noise in the digital image.
	Viewing quality can only be improved by		Digital images can be improved by processing
	increasing the brightness of the LAMP		on a computer to change the density, contrast,
	that illuminates the film.		sharpness, and other factors.
	The quality of films that are not exposed		Images that were not exposed correctly can be
	correctly cannot be improved.		improved. For example, software parameters
			can improve image density and contrast.

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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

aerial

latent

image

image

STORAGE PHOSPHOR SCREEN Charged storage phosphors proportional to X-ray energy

absorbed by screen.

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

H194_5033BC

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When a STORAGE PHOSPHOR SCREEN is exposed to X-rays:

•special PHOSPHOR on the SCREEN absorbs the radiation in degrees of intensity determined the body part 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 PHOSPHOR	Description
SCREEN
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	When the charged PHOSPHOR on the SCREEN is stimulated by
luminescence	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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Characteristics of the
STORAGE PHOSPHOR	Description
SCREEN
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 expose 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

pixel code value

(0 - 4095)

SAMPLING

Y

image	image
sample	matrix
grid
X
analog image	digital image
(continual values)	(discrete values)

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 brightness 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 vertical 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 information 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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Section 3: Sequence of Operation

Overview of Workflow Using the CR 825/850 SYSTEM

1The Radiology Department receives an exam request.

2The 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 information 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.

3The operator can select network nodes to send the image data to.

4The operator uses a CR CASSETTE to do the exam, capturing the latent image on the

STORAGE PHOSPHOR SCREEN.

5Using 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.

6The 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.

7The 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

8If necessary, the image can be processed and sent to network 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.

2The 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

1The operator loads the CASSETTE into the INPUT SLOT until the CASSETTE reaches the CASSETTE ENTRY SENSOR S1.

2The 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.

3The 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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4The MCPU BOARD A2 sends:

•“CASSETTE Detected” message to the MSC BOARD A1

•“Scan Request” message to the INTERNAL PC

5The 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”

6The 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.

7The CASSETTE DRIVE MOTOR M2 actuates. The MOTOR drives the TIMING BELTS, which rotate the DRIVE ROLLERS.

8The DRIVE ROLLERS drive the CASSETTE to the back until the CASSETTE REAR SENSOR S3 detects the CASSETTE.

9The CASSETTE REAR SENSOR S3 sends a signal to the MSC BOARD A1 to deactuate the MOTOR.

10After a delay of 20 ms, the MSC BOARD A1 deactuates the MOTOR.

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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

1The DUPLEX CAM moves from position 1 directly to position 3. See “DUPLEX CAM

AY.”

2When 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.

3The MSC BOARD A1 sends a signal to the MCPU BOARD that the CASSETTE is loaded.

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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

1The SLOW SCAN MOTOR starts rotating the LEAD SCREW, pulling the PLATE 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 PLATE steady during scanning and when they leave and move back into the CASSETTE.

2When 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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3The 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

1The MCPU BOARD A2:

•actuates the GALVO

•sends a signal to the MSC BOARD A1 to start the scan, which starts the SLOW

SCAN MOTOR

•sends a signal to the INTERNAL PC that the scan is starting

2The INTERNAL PC displays a TIMED PROGRESS BAR on the TOUCH SCREEN

MONITOR. This is a graphic display only and not a real-time indication of the status of the scanning operation.

3The SLOW SCAN MOTOR rotates, moving the SCREEN at a continual speed through the field of scan in the slow scan direction.

4The 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.

5When the end of the scan is reached, the MSC BOARD A1 sends a status message to the MCPU BOARD A2.

6The MCPU BOARD A2 de-energizes the PMTs, GALVO, and the LASER.

7The 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

1The 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.

2The SLOW SCAN MOTOR actuates and moves the SCREEN into the erase position, determined by the counts of the SLOW SCAN ENCODER.

3The SLOW SCAN MOTOR stops and waits for a response from the MCPU BOARD A2.

4The MCPU BOARD A2 sends the “Erase” command and time to the MSC BOARD A1, which actuates the ERASE LAMPS.

5The 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.

6When 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

1The 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

2The MSC BOARD A1 reverses the SLOW SCAN MOTOR, which moves the PLATE up into the open CASSETTE SHELL.

3The PLATE POSITIONING AY guides the PLATE into the CASSETTE SHELL from the back side.

4When 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

1The MCPU BOARD A2 sends an “Eject Cassette” command to the MSC BOARD A1.

2The CAM MOTOR M1 energizes.

3The DUPLEX CAM moves toward position 4. See “DUPLEX CAM AY.”

4When 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