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,LORAD M-III MAMMOGRAPHY

I

:

SYSTEM

M-III SERVICE MANUAL LIST OF EFFECTIVE PAGES PAGE

p---

copyright i through xi . . . . . 1-1 & 1-2 1-3 through 1-6 1-7 1-8 1-9 1-10 1-11 1-12 through 1-14 2-1 & 2-2 2-3 & 2-4 2-5 through 2-9 . . 2-10 through 2-31 2-32 2-33 through 2-35 3-1 & 3-2 3-3 3-4 3-5 3-6 through 3-13 3-14 through 3-17 3-18 3-19 through 3-21 3-22 through 3-29 4-1 & 4-2 4-3 4-4 4-5 4-6 4-7 : 4-8 through 4-12 .

REVISION

. . . . . . . . . . . . . . . . . . . . . . . . . . . ..

9 1 0 4

4-13 4-14 4-15 4-16 through 4-19 4-20 through 4-27 . . . . . . . . . . . . . . . . 5-1 5-2 5-3 , 5-4&5-5 5-6 5-7 5-8&5-9 5-10 5-11 5-12 5-13 & 5-14 5-15 through 5-18 5-19 5-20 through 5-25 . . . . . . . . . . . . . . . . 5-26 5-27 5-28 6-1 & 6-2 6-3 through 6-8 . . . . . . . . . . . . . . . . . . 7-1 : 7-2 & 7-3 7-4 7-5 through 7-7 8-1 through 8-3 8-4 through 8-12 9-1 9-2 9-3

6 5

0 '"

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. . . . . . .. . . . . . . . . . . . . . . . . . . . . .

'"

" . . . . . . . . . . . . . . . . .. . . . . . . . . . . . ,

. . . . . . . . . . . . . .. .. . . . . . . . . . . . .

REVISION

PAGE

11 0 9 0 8 7 9 12 9 0 3 0 1 0 7 1 0 7 0 1 0 1 0 2 0

Revision zero (0) Indicates Initial release of manual.

REVISION NUMBER

o (Initial

DATE . 6/90

Release)

1 2 3

:

. 7/90 . 7/90 . 8/90

8 9

. 10/90 . 10/90 . 11/90 1/91 . 3/91 . 5/91

10

. 7/91

11

. 3/92

12 13

5/92

4 5

6 7 .....•....................•...............

The total number of pages in this document is 170. Except for the initial release, all pages. of this document will be designated with a revision number at the lower right comer of each revised page.

7192

1

0 1 0 . . . . . . . . . . . . . 7 4

7 0 4 0 4 3 4 0 4 7 0

2 . . . . . . . . . . .. . 0 2 11 6 ' 0 . . .. . . . . . . . . . 7 7 0 1 7 7 9 7 0 7

LO RA.D® Medical Systems, Inc.

This manual is copyrighted with all rights reserved. Under copyright laws, this manual may not be copied, in whole or pan, without the written consent of LORAD Medical Systems, Inc. The same proprietary and copyright notices must be affixed to any permitted copies as were affixed to the original. This exception does not allow copies to be made for others, whether or not sold, but all of the matierial purchased may be sold, given, or loaned to another person. Under the law, copying includes translating Into another language or format.

LORAD, Permagrid and StereoLoc of LORAD Medical Systems, Inc.

© LO RAD

are registered trademarks

Medical Systems, Inc. 1990

Eagle Road, Commerce Park Danbury, Ct. 06810 (203) 790-1188

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

M-III SERVICE MANUAL TABLE OF CONTENTS

SECTION ONE - GENERAL INFORMATION AND INSTALLATION 1.1

1.2

Introduction to the M-III

•

•

•

•

•

•

•

•

•

•

•

•

•

•

•

1-1

••

Unit Description How to Use the Service Manual . . . . . . . . . . . . . . . . . . . . . . . . . . .. Tools and Equipment Required Unit Layout. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

1.1.5

Safety Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

1-1 1-1 1-2 1-4 1-4

Receiving Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-5 Unpacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5 Standard Items Supplied . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . .. 1-6 Notation of Compliance Labels and Control Number . . . . . . . . . . . .. 1-8

Installation 1.3.1 1.3.2 1.3.3 1.3.4 1.3.5 1.3.6 1.3.7

1.4

•

1.1.1 1.1.2 1.1.3 1.1.4

1.2.1 1.2.2 1.2.3

1.3

0

-, . . .. 1-8

Installation of the Radiation Shield Input Power Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Input Power Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Power Cable Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 'Target mAs Selection DIP Switch Configuration Attachment of Accessories

1-8 1-8 1-10 1-10 1-10 1-12 1-12

Transfer to User . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-13 1.4.1 1.4.2 1.4.3

Initial Testing User Training Manuals and Accessories

1-13 1-13 ' 1-14

SECTION TWO - M-III SYSTEM CHECKS 2.1

Pre-Turn On Checks 2.1.1 2.1.2

2-1

Cabling 2-1 Radiation Shield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

Revision - 10

LORAD

M-III SERVICEMANUAL

MEDICAL SYSTEMS

(Table of Contents continued)

2.1.3 2.1.4

Mechanical Integrity Auto-Aperture and Fixed Apertures

. 2-1 . 2-1

2.2

Power-Up Checks

. 2-1

2.3

Menu/Front Panel Controls Checks

. 2-3

2.3.1 2.3.2 2.3.3 2.3.4 2.3.5

. . . . .

2.4

Power-Up CRT Display Cursor Key Function Entry Keypad Function DatelTime Clock Exposure Control Keys

C-Arm Functional Checks 2.4.1 2.4.2

2.5

2.6

. 2-4

C-Arm UP and DOWN C-Arm Rotation

-

. 2-4 . 2-5

Interlocks

. 2-5

2.5,1 2.5.2 2.5.3

C-Arm Safety Switch Aperture Interlock Door Interlock

. 2-5 . 2-5 . 2-6

Accessory Detection and Recognition

. 2-6

2.6.1 2.6.2 2,6.3 2.6.4

2.7

:

2-3 2-3 2-4 2-4 2-4

Image Receptor Detection Bucky Recognition Mag Tray/Stereo Detection Localization Tray Recognition

-

. . . .

2-6 2-6 2-7 2-7

Compression System Checks

. 2-8

2.7.1 2.7.2 2.7.3 2.7.4

. . . .

Motorized Compression Drive Manual Compression ; Compression Thickness Display Compression Release Modes

2-8 2-8 2-9 2-9

2.8

Footswitch Check

2.9

Printer Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-9

2-9

ii

Revision - 10

•

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

(Table of Contents continued)

2.10

X-Ray Tube Current Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10 2.10.1

2.11

2.12

-------

2-10

mA Measurement Setup

Tube Voltage Potential Check

2-13

2.11.1

2-13

Tube Potential Check Procedure

Automatic Exposure Control Check

2-15

2.12.1

2-15

AEC Check Procedure

2.13

Bucky Grid Performance Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-16

2.14

Checking Half Value Layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

2.15

Checking Reproducibility

and Linearity - Manual Mode . . . . . . . . . . . . . . . . 2-18

2.16

Checking Reproducibility

and Linearity - Auto-Time Mode

2.17

Checking Reproducibility

and Linearity - Auto-KV Mode . . . . . ... . . . . . . . . 2-21

2.18

Timing Accuracy - Manual Mode

2-22

2.19

Maximum mAs In Auto-Time Mode

2-23

2.20

Checking the X-Ray Shielding of the Image Receptor Tray

2-24

2.21

Checking the X-Ray Shielding of the Tubehead

2-26

2.22

Light Field

2-26

2.22.1

2-26 2-29

2.22.2 2.22.3 2.23

Light Field Illuminance Test Light Field Alignment Certification Verification of X-Ray Beam Alignment

Checking the E¥xposureCounter

2-20

2-32 2-35

SECTION THREE - X-RAY CONTROL THEORY OF OPERATION .----...

3.1

Introduction

3-1

iii

Revision - -10

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

(Table of Contents continued)

3.2

Power Distribution

3.2.1 3.2.2 3.2.3 3.2.4 3.3

3.3.4

3.3.5 3.3.6 3.3.7 3.3.8

.-.

3.4

Input Power Panel Isolation Transformer System AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . System DC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Microprocessor

3.3.1 3.3.2 3.3.3

3.4.4

High Voltage

3.6

Automatic

3.7

Interlock

...

3-1

3-2 3-2 3-3 3-4

:.....................................

. . . . . . . . . . . . . . . . . . . . . . . . . 3-4 . . . . . . . . . . . . . . . . . . . . . . . . . 3-6

3-6 ;...................... 3-9 . . . . . . . . . . . . .. . . . . . . . . . . . . 3-15

3-15 3-15 . . . . . . . . . . . . . . . . . . . . . . . . . 3-15 3-17

Board

Anode Motor Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-17 Filament Supply 3-19 Filament Control Signals ". . . . . . . . . . . . . . . . . 3-19 Filament Regulation 3-21

3.5

3.6.1 3.6.2 3.6.3 3.6.4 3.6.5

Board

CRT Interface . . . . . . . . . . . . . . . . Keyboard Interface c-Arrn Keypad Interface Exposure Control C-Arm Angle Display Driver . . . . . . C-Arm Status Inputs Printer Interface Real Time Clock . . . . . . . . . . . . . .

Tube Control

" 3.4.1 3.4.2 3.4.3

. . . . 3-1

Generator

Exposure

3-22

.. "......................................

Control

3-25

Circuit

AEC Sensor Board ". . AEC Signal Path - Microprocessor Board ~. . . . . . . . . . . . AEC Signal Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AUTO-TIME Mode Exposure Termination " AUTO-KV Mode Exposure Termination Circuits

".....

3-25 3-26 3-26 3-26 3-27 3-28

3.7.1

Radiation Shield Interlock

3-28

3.7.2 3.7.3

C-Arm Safety Switch Aperture Interlock

3-28 3-28

iv

Revision - 10

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

(Table of Contents continued)

SECTION FOUR - ELECTROMECHANICAL

4.1

C·Arm Drive, Power Control Board 4.1 .1 4.1.2 4.1 .3 4.1.4 4.1.5 4.1.6 4.1.7 4.1.8 4.1.9

4.2

THEORY OF OPERATION

4-1

Linear Actuator Assembly 4-1 C-ARM UP/DOWN and Safety Switch 4-1 C-Arm Compression Subsystem 4-6 Compression UP/DOWN/RELEASE 4-8 Compression Drive Circuit Description 4-10 Compression Signal Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-11 Compression Thickness 4-11 C-Arm Rotation Brake . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12 Light Field :.. 4-12

C-Arm Detectors and Switches 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5

C-Arm Angle Detector . . . . . . . C-Arm Accessory Detect Board Auto-Aperture Detect Board . . . Mag Tray Detect Board . . . . . . Radiation Shield Switch . . . . . .

4-14 . . . . .

SECTION FIVE - REMOVAL AND REPLACEMENT

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

. . . . .

4-14 4-18 4-24 4-27 4-27

PROCEDURES

5.1

General Information

5.2

Control Console Cabinet Layout

5-1

5.3

Removal and Replacement of Control Console Assemblies

5-4

5.3.1 5.3.2 5.3.3 5.3.4 5.3.5

5.3.6 5.3.7 5.3.8 5.3.9 5.3.10 5.3.11 5.3.12

. . . . . . . . . . . . . . . . . . . . . . 5-1

Rear Cover (Pushbar Cover) . Left and Right Side Panels DATAPORT Keyboard and Panel Rear Vertical Travel Assembly Cover Panel Upper Front VTA Cover Panel Lower Front VT A Cover Panel . . . . . . . . . . . . . High Voltage Generator. . . . . . . . . . . . . . . . . . Low Voltage Power Supply .... ... __ .... Power Control Board . . . . . . . . . . . . . . . . . . . . X-Ray Tube Control Board Microprocessor Board . . . . . . . . . . . . . . . . . . . Peripheral Interface Board . . . . . . . . . . . . . . . .

v

5-4 5-7 5-7 5-7 5-7 . ........ . .. ........ __ .... __ . ....... ...

...... ...... _ ... __ ... .. .

5-8

5-8 5-9 5-9 5-9 . . . . . . . . . . . . . . . . 5-9 . . . . . . . . . . . . . . . . 5-9 Revision - 10

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

(Table of Contents continued)

5.3.13 5.3.14 5.3.15

5.4

C-Arm Assembly Layout 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5

5.5

5-10

X-Ray Tubehead Assembly .... Compression Device . . . . . . . . . Image Receptor Tray Switches. .. ....... ....... Miscellaneous C-Arm Component

, . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 5-14 . . . . . . . . . . . . . . . . . . . . . . . . . . . 5·14 Layout 5-14

Removal and Replacement of C-Arm Components 5.5.1 5.5.2 5.5.3 5.5.4 5.5.5 5.5.6 5.5.7 5.5.8

5.5.9 5.5.10 5.5.11 5.5.12 5.5.13 5.5.14 5.5.15

5.5.16 5.5.17 5.5.18 5.5.19 5.5.20 5.5.21

5.6

CRT Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-10 Input Power Panel 5-10 Printer Power Supply 5-10

Patient Handle C-Arm Side Covers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-Arm Top Cover C-Arm Upper Rear Cover C-Arm Lower Rear Cover Compression Carriage Covers Tubehead Enclosure Cover . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . Compression Motor Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Beam Limiting Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Image Receptor Tray Cover AEC Position Detector PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . AEC Amplifier PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Accessory Detect Board X-Ray Tube Light Field Lamp Maa Trav/Stereo Detector PCB Rotation Sensors Compression Sensor. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Auto-Aperture Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Localization Tray Sensor PCB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . LED Angle Display Board

Fuse Locations and Ratings

5-15 5-15 5-15 5-15 5-15 5-17 5-17 5-17 5-17 5-18

5-20 5-20 5-20 5-21 5-21 5-21 5-22 5-22 5-24 5-26 5-26 5-26 5-27

SECTION SIX - CHECKING AND ADJUSTING LIGHT FIELD 6.1

General

. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

vi

Revision - 10

LORAD MEDICAL

SYSTEMS

M-IJI SERVICE MANUAL

(Table of Contents continued)

6.2

Illuminance of Light Field Certification

6.3

Light Field Alignment Certification

6.4

Light Field Alignment 6.4.1

Test.

. . . . . . . . . . . . . . . . . . . . . . . . 6-1

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3

Procedures

6-5

light Field Alignment

6-5

SECTION SEVEN - X-RAY FIELD ALIGNMENT PROCEDURE 7.1

Alignment

7-1

of X-Ray Beam

SECTION EIGHT - M-III ELECTRICAL CALIBRATION PROCEDURES

---

8.1

DAC Reference and Bucky Offset

8.2

KVP Calibration

8.3

Filament Calibration

8.4

AEC Callbra.tion Procedure

8.5

Compression

8.5.1 8.5.2

8-1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-4 "

_ . . . . . . . . . . 8-10

Compression Force Calibration Compression Thickness Calibration

Bucky Calibration

8.7

Accessory

8-7

_. . . . . . . . . 8-10

Tray

8.6

8.7.1

_. . . . . . . . . . . . . 8-1

8-10

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-11

Detect Calibration

_

__

8-11

Accessory Detect Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . 8-12

SECTION NINE - M-III MECHANICAL CALIBRATION PROCEDURES 9.1

Compression

Tray Chain Tension Adjustment

9-1

.------..,

vii

Revision - 10

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

(Table of Contents continued)

9.2

Compression Sensor Adjustment

9-2

9.3

Rotation Sensor Adjustment

9-3

9.4

Localization Tray Sensor Adjustment

9-3

M-III SERVICE MANUALLIST OF FIGURES

SECTION ONE: Figure Figure Figure Figure

1-1: 1-2: 1-3: 1-4:

The M-III Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Compliance Labels and Identification Plate . . . . . . . . . . . . . . . . . . .. Extended Radiation Shield M-1I1Input Voltage Configuration

1-3 1-7 1-9 1-11

2-2

2-2: 2-3: 2-4: 2-5: 2-6: 2-7: 2-8:

M-1I1Apertures Waveform Patterns High Voltage Generator Test Well Image Receptor Tray Test Points Tubehead Test Points l-ight Field Test Areas Coned-Down Aperture Coned-Down Image on Tray

2-12 2-14 2-25 2-27 2-28 2-30 2-31

Figure 2-9:

LORAD Field Alignment Template

2-33

SECTION TWO: Figure Figure Figure Figure Figure Figure Figure Figure

2-1:

SECTION THREE: Figure Figure Figure Figure Figure

3-1 3-2: 3-3: 3-4: 3-5:

M-III CRT Interface Signalling 3-5 Keyboard Interface and Input Power Signals 3-7 M-III Exposure Sequence 3-10 Exposure Timing Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-12 C-Arm Angle Display Drive 3-16

viii

Revision - 10

-r=-,

LORAD

MEDICAL SYSTEMS

M-III SERVICE MANUAL

(List of Rgures continued)

Figure Figure Figure Figure Figure

3-6: 3-7: 3-8: 3-9: 3-10:

Anode Motor Control Signalling Filament Control Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High Voltage Generator Control Signals . . . . . . . . . . . . . . . . . . . . . . Automatic Exposure Control Signals Interlock Signals '.' . . . . . .

3-18 3-20 3-24 3-27 3-29

Linear Actuator Assembly Actuator Control Signals Compression Control Signals. . . Compression Carriage Assembly Compression Thickness Interface Rotation Brake Control Signals Collimator Lamp Signals Detector Boards and Signals . . . C-Arm Angle Detector Signals . . C-Arm Accessory Detect Signals Bucky Interface Signals Auto-Aperture Detect Signals. . . Mag Tray Detect Signals . . . . . . Radiation Shield Switch Signal

4-2 4-3

SECTION FOUR: Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure Figure

4-1: 4-2: 4-3:

4-4: 4-5: 4-6: 4-7:

4-8: 4-9: 4-10:

4-11 : 4-12: 4-13: 4-14:

:.........

. . . . . . . . . . . . . . . . . . . . . . . . . . . 4-5 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 Signals . . . . . . . . . . . . . . . . . . . . . 4-9 4-13

4-15 ..... ..... ....... .. ....... ... ........ . . ......... .. ...... . ' .......... ...... ... ........... ........

. . . . . . . . 4-16 .. . . . . . . 4-17 . . . . . . . . 4-19

4-21 . . . . . . . . 4-23 . . . . . . . . 4-26

4-27

SECTION FIVE: Figure 5-1: Figure 5-2: Figure Figure Figure Figure Figure

5-3: 5-4: 5-5: 5-6: 5-7:

Figure 5-8: Figure Figure Figure Figure Figure

5-9: 5-10:

5-11: 5-12: 5-13:

Control Console PCB/Printer Locations 5-2 Control Console PCB Locations, High Voltage Generator, and Isolation Transformer 5-3 Control Console Component/Cover Removal 5-5 Control Console Component/Cover Removal (continued) 5-6 C-Arm Assembly Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-11 Compression Device and Single Collimator Blade . . . . . . . . . . . . . . . 5-13 C-Arm Component/Cover Removal 5-16

C-Arm Component & Detector .Board Locations

5-19

Rotation Angle Potentiometer 5-23 Rotation Potentiometer Assembly 5-24 Compression Potentiometer. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-25 Compression Potentiometer Assembly . . . . . . . . . . . . . . . . . . . . . . . 5-25 Fuse Locations and Ratings 5-28

ix

Revision - 10·

LORAD MEDICAL

SYSTEMS

M-III SERVICE MANUAL

(List of Rgures continued)

SECTION SIX: Figure Figure Figure Figure .Figure

6-1: 6-2: 6-3: 6-4: 6-5:

Receptor Tray Light Field Test Points 6-2 Coned-Down Fixed Aperture 6-2 Coned-Down Aperture Projected Light Field .. . . . . . . . . . . . . . . . . . 6 4 Collimator Light Alignment Sample . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6 Light Field Bracket Adjustment 6-8 a

SECTION SEVEN: Figure 7-1: Figure 7-2: Figure 7-3:

LORAD Field Alignment Template . . . . . . . . . . . 7~3 Beam Limiting Assembly Including the M-1I118x24 em Auto-Aperture. 7-4 M-1I124x30 em Fixed Auto-Aperture : 7-6

SECTION EIGHT: Figure 8-1: Figure 8-2: Figure 8-3:

High Voltage Generator Adjustment Points . . . .. . . . . . . . . . . . . . . . 8-3 Waveform Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-6 AEC Calibration Flowchart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-9

SECTION NINE: Figure 9-1: Figure·9-2:

Compression Tray Chain Tension Adjustment Compression Potentiometer Adjustment Location

x

9-1 9-2

Revision - 10

LORAD

M-III SERVICE MANUAL

MEDICAL SYSTEMS

M-III SERVICE MANUAL LIST OF TABLES

SECTION ONE: Table 1-1:

S 1 DIP Switch Configuration

.....

. . . . . . . . . . . . . . . . . . . . . . . ..

1-12

SECTION TWO: Table 2-1: Table 2-2:

X-Ray Tube Current Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-11 AEC Exposure Test Settings 2-16

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M-III SERVICE MANUAL

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SECTION ONE: GENERAL INFORMATION AND INSTALLATION 1.1

INTRODUCTION TO THE M-III The LORAD M-1I1 combines LORAD Clean Power Mammography technology with an easy-to-operate, fully-controllable computer system. The full-featured system provides manual or automatic x-ray control and accommodates a full range of options.

1.1.1

Unit Description The M-III, features three menu-driven exposure modes (Manual, Auto-Time, and Auto-KV) and is equipped with a dual focal spot x-ray tube. The unit accommodates all LORAD manufactured attachments such as 'the cassette holders, compression trays, localization trays, magnification tray, Bucky grids and Permagrids, and the StereoLoc Localization and Biopsy System. M-1I1mechanical operations as well as the x-ray system operations are controlled and monitored by the internal computer system with the status of each operation displayed on the CRT screen. The M-III control system contains diagnostic routines that monitor system operation before, during, and after x-ray exposure. If a malfunction is detected by the diagnostic system, further operation is prevented until the detected fault is cleared, and a fault message is displayed at the bottom of the CRT. .

1.1.2

How to Use the Service Manual The M-III Service Manual has nine sections. The nine sections contain the following information: Section 1: General system descriptions and the information necessary for a qualified technician to unpack, assemble, and prepare the system for operation. Section 2: General system checks as well as certification tests. Section 3: Descriptions of the x-ray exposure circuits, circuit interactions, and signal routing.

-~

.

Section 4: Descriptions of the M-III's electro-mechanical functions.

...•

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M-III SERVICE MANUAL

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Section 5: Location, removal, and replacement instructions for M-1I1components, boards, sensors, etc. Section 6: M-III light field illuminance and alignment tests. Section 7: Directions for x-ray beam alignment, after replacing the x-ray tube. Section 8: Electrical calibration procedures for system setup, x-ray tube current and voltage, etc. Section 9: Mechanical adjustments for the M-III.

System troubleshooting can be performed using the circuit descriptions in Section 3, which trace the circuit interactions for each machine function, and Section 4 which describes the electro-mechanical device and circuit interactions. In addition, performing the calibration procedures will often identify a failed assembly.

Replacement of some electrical assemblies requires that the corresponding certification procedure and, if necessary, the alignment and calibration procedure be performed to verify the machine's conformance to specification.

1.1.3

Tools and Equipment Required

The following is a list of tools necessary for servicing the M-III unit. 1. 2. 3. 4. 5. 6. 7. 8. 9.

standard hand tools; 1/16-inch (1.6 mm) lead sheet; hex key set; 1/16-inch (1.6 mm) lead sheet with a 2.4-inch (6 ern) diameter hole in it; meter stick; light meter probe; DC voltage divider; field alignment template; 3-1/2 digit volt-ohm-multimeter;

10.

oscilloscope;

11. 12. 13.

Victoreen Model 660 radiation ratemeter with 660-1 probe or equivalent; 100 sq cm radiation scatter probe; 4-inch mirror or reflective tape.

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LORAD

M-III SERVICE MANUAL

MEDICAL SYSTEMS

j

PATIENT HANDLE

BEAM UMfTlNG SUDE

RAD~TION SHIELD

l

C-ARM ROTATION READOUT

DATAPORT SCREEN FIXED APERTURE__

••.l----W-~

COMPRESSION

~R~GE-------~~

(-ARM PUSHBUTTONS ------

CIRCUIT BREAKER & INPUT POWER PANEL

.J

PIVOT TUBE

DATAPORT KEYPAD FOOT BRAKE

FOOT BRAKE

Figure 1-1: The M-III Unit

Page 1-3

. Revision - 4

LORAD MEDICAL 1.1.4

SYSTEMS

M-III SERV

Unit Layout

~

_

The M-III Mammography System pictured in Figure 1-1 consists of three assemblies: the DATAPORT CRT screen, Control Console, and the C-Arm.

m~

The CRT displays all x-ray exposure options and selections in Manual, Auto-Time, and Auto-kV exposure modes. Data lines on the screen list the status of mechanical operations (specifically, C-Arm angle, compression tray height, and presence of attachments). The CRT is installed on top of the Control Console. The Control Console contains the DATAPORT keyboard, the x-ray exposure drive components, C-Arm rotation sensors, and a linear actuator assembly that drives the CArm up and down. The microprocessor, system AC/DC power supplies, and a printer are also housed in the Control Console. The unit is mounted on two wheels and two casters. An input power receptacle on the Control Console opposite the OATAPORT keyboard connects the unit to an AC power source. The CRT video cable from the microprocessor and the AC power cord are mounted in an enclosure at the right rear of the M-lii. A system circuit breaker is mounted just above the receptacle. The C-Arm houses the x-ray tube and beam limiting assembly, the breast compression device, C-Arm control keypads, the image receptor tray, and the accessory sensors and AEC sensor built into the image receptor tray.

1.1.5

Safety Warnings

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1.2 1.2.1 ----..

SYSTEMS

M-III SERVICE MANUAL

RECEIVING INSTRUCTIONS Unpacking The LORAD unit is shipped crated on its two wheels and two casters. Upon receipt, all

crates and boxes should be inspected for external damage that may have occurred during shipment. If any damage is evident, have it noted on the shipping manifest and notify LORAD of the incident. If shipping damage is of a concealed nature, contact the carrier as soon as such damage is found, and request an inspection for shipping damage. Normally, any claims for shipping damage must be completed within 15 days of receiving the shipment. Upon receipt, all crates and boxes should be opened, and their contents checked against the packing list and sales order. Any discrepancies should be reported to LORAD. If it is necessary to re-box any items for future installation, use the original packaging materials. Do not store the radiation shield flat.

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LORAD 1.2.2

MEDICAL SYSTEMS

M-III SERVICE MANUAL

Standard Items Supplied

1.

M-III Series Machine with CRT Monitor;

2.

Radiation Shield;

3.

Operator Manual and Service Manual;

4.

Input Power Cable;

5.

Fixed Aperture Assemblies: a)

18 x 24 / 24 x 30 cm Auto-Aperture;

b)

1 Conned-Down Aperture for Magnification/Conned-Down Studies;

c)

1 Spot Aperture for Magnification/Conned-Down Studies.

6.

Plastic Compression Tray (10 Ineh/25 em);

7.

Plastic Compression Tray (4 Inch/10 ern):

8.

Localization Tray - Perforated (4 Inch/10cm);

9.

Front Loading Cassette Holder - 18 x 24 em;

10.

Front Loading Cassette Holder - 24 x 30 cm;

11.

Side Loading Cassette Holder - 18 x 24 cm;

12.

2 Dual Compression Footswitches and V-connector;

13.

LORAD Single Pass Bucky Grid Device (18 x 24 em);

14.

1.BX Magnification Tray;

15.

Abdomen Shield;

16.

Face Shield.

-~-

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Revision - 4

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

..

r-

II

...•

c:=J

fij1

m

"-

[Qj

I[

-- .. ~

0

V

~I

~

11

=u

-

'--

~

1 2

3

4 5 6

-'.

_=:0 Main Identification Plate X-Ray Tube Compliance Label H.V. Generator Compliance Label Beam Limiting Device Compliance Label X-Ray Control Compliance Label Image Receptor Support Device Co mp Harrce Label

Figure 1-2: Compliance

Labels and Identification

Page 1-7

Plate

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LORAD MEDICAL 1.2.3

SYSTEMS

M-III SERVICE MANUAL

Notation of Compliance Labels and Control Number. The M-1I1conforms to all applicable FDA regulations. Labels addressing the certifiable components are fixed to the unit at several points, as shown in Figure 1-2. The main identification label, containing the equipment model number, serial number, and control number, is located near the input power receptacle.

Compliance labels are located near the power cord entrance, inside the High Voltage Generator cage, behind the tubehead, and near the control panel.

Obtain the machine's control number from the main identification label (Figure 1-2), and write it down on the inside cover of both the Operator's and Service manuals. The control number is used to track units for warranty and service purposes, and will be requested should it become necessary to contact LORAD regarding the machine.

1.3

1.3.1 -

INSTALLATION

Installation of the Radiation Shield (Figure 1-3) TO mount the radiation shield, first position it hext to the column on the right side of the unit, while resting it at its base. Align its hinge pins with the holes of the hinge fixtures on the column, then lower the shield into place. An easy method is to support much of the door-like shield's weight on one toe while maneuvering it with the toe and both hands to align both pins with the hinge fixture holes.

1.3.2

Input Power Measurement Before connecting the M-1I1to a source of 230-volt AC power, first measure the voltage at the outlet receptacle. Evaluate the range of voltage that will normally be available to the M-lii. Inquire as to any history of voltage fluctuations or voltage related problems that have

occurred in other equipment at the Site. Once the most probable voltage range has been determined, the M-1I1isolation transformer can be reconfigured as necessary.

The M-III is factory-configured

for an input voltage range of 197.6 to 218.4 volts AC.

Page 1-8

Revision - 5

--

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

EXTEN DED RADIA TION SHIELD

,,

I

,,

I

I

,, ,

I I I

I

\

I

1:; 0-

.........I Cl )

-

-

1---

-

L-

r---

•

.

I--

II

II

-

Figure 1-3: Extended Radiation Shield

Page 1-9

Revision - 0

LORAD MEDICAL 1.3.3

M-III SERVICE MANUAL

SYSTEMS

Input Power Configuration To reconfigure the isolation transformer taps:

1.3.4

1.

PERFORM THIS PROCEDURE

BEFORE CONNECTING

POWER CORD.

2.

Remove the left and right side covers from the Control Console.

3.

To access the input side of the isolation transformer, remove the four bolts that secure the High Voltage Generator to the middle rail structure, and slide the generator several inches toward the C-Arm.

4.

The input side of the isolation transformer is the side nearest the C-Arm of the M-lilo

5.

Configure the transformer input wiring and tap as shown in Figure 1-4.

6.

Attach the generator in its former position and replace the left and right side covers of the Control Console.

Power Cable Connection First check that the input circuit breaker, located above the input power receptacle on the unit's back panel, is in the Off position. Then, insert and lock the mating end of the cable into the receptacle. Plug the other end of the cable into the line power outlet. Do not yet turn the input circuit breaker nor the unit's front panel switch, ON.

1.3.5

Target mAs Selection During the initial unit setup, a pre-selected exposure time is set on the M-III Microprocessor Board as a "window" from which to determine the need to raise the kV level. The selected window is indicated mid-screen on the Exposure Control Line called MAS when the Auto-KV exposure mode is selected (EXP MODE: AUTO-KV).

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LORAD

M-III SERVICE MANUAL

MEDICAL SYSTEMS

o o 120

198 TO 218 VOLTS AC

o 120

104

o

o 213 TO 235 VOLTS AC

120

o o 104

o

228 TO 252 VOLTS AC

.--

Figure 1-4: M-III Input Voltage Configuration

Page 1-11

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LORAD MEDICAL

SYSTEMS

M-III SERVICE MANUAL

(mA in Auto-KV mode is fixed at 80 for Large Focal Spot and 20 for Small Focal Spot.). The three possible exposure times, 1 second, 1.5 seconds, or 2 seconds, are pre-set via the default procedures within the "User Option Menu".

1.3.6

Dip Switch

Configuration

(S1)

Switch (S 1) is an eight position Dip Switch located on the Microprocessor Board. Each switch position is set at the factory and should never be changed. Table 1-1 (below) illustrates the configuration of each Dip Switch on S1.

Table 1-1: S1 Dip Switch Configuration Dip Switch

Number

.Configuration

1.3.7

1 OFF

Attachment

A.

2 OFF

3 OFF

4

5

ON

OFF

678 OFF

OFF

OFF

of Accessories

Remote Compression

Up/Compression

Down Footswitch:

Insert the plug of the remote compression up/compression down footswitch into the jack on the left front side of the Control Console. Ensure that the plug is inserted securely, as far as it will go. If two footswitches are to be connected, use the supplied V-connector ..

B.

LORAD Bucky To mount the LORAD Bucky device, slide it onto the image receptor tray. The locking leaf spring on the Bucky's lower frame rail should be on the right side when facing the C-Arm from the patient position. (The electrical connector on the left rear of the Bucky locks into

an electrical socket on the left side c-Arrn rail). If the Bucky electrical connector does not insert easily when the Bucky is slid onto the tray, it may be necessary to realign the tray as follows. (1)

Remove or loosen the 6-32 set screws beneath each side of the image receptor tray's top cover and slide the Bucky onto the top of the image receptor tray while

Page 1-12

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LORAD

MEDICAL SYSTEMS

M-III SERVICE MANUAL

carefully attaching the Bucky arm electrical connector to the C-Arm. The Bucky connector in the c-Arm has some movement as well as the loosened receptor tray top; carefully position the two to make the proper Bucky electrical connection.

(2)

C.

Re-tighten the screws beneath the top cover of the image receptor tray. Be sure the Bucky sits perfectly flat on the tray before finally tightening each side screw.

Cassette Holder or Permagrid Assembly: Mount the cassette holder or Permagrid in the same way as directed for the Bucky.

D.

StereoLoc System: Refer to the StereoLoc Installation Manual supplied with that device.

E.

Compression Accessory: Mount the desired compression accessory (tray) onto the compression carriage by aligning the accessory's pins with the holes on the carriage and pressing it into place until a locking motion is felt.

1.4

1.4.1

TRANSFER TO USER

Initial Testing Read the LORAD Operator's Guide before turning the unit on. Read through the operational checks described in Section 2 of this manual.

1.4.2

User Training When installation has been completed, instruct the user in the identification and installation of all accessories and, if requested, outline the basic operation of the M-III unit.

Page 1-13

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LORAD 1.4.3

M-IJI SERVICE MANUAL

MEDICAL SYSTEMS

Manuals and Accessories Once installation is completed, make sure that all unmounted accessories are stored safely in a manner that will prevent any scratching or damage. Inform the technologist of their location. Place both the Operator's and the Service Manuals in a secure location. Ensure that the technologist knows the location of the Operator's Manual.

Page 1-14

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M-III SERVICE MANUAL

SYSTEMS

SECTION TWO: M-III SYSTEM CHECKS

2.1 2.1.1

PRE-TURN ON CHECKS Cabling Check that the power input cable is not frayed or otherwise damaged, and that the housings of the connectors are not cracked or damaged. Be sure both ends connect securely.

2.1~2

Radiation Shield Check the placement of the radiation shield. Be sure that it blocks the operator when opened.

2.1.3

Mechanical Integrity Ensure that the unit has no loose panels, loose hardware, jammed or broken switches, dents or scratches. .

2.1.4

Auto-Aperture and Fixed Apertures Standard equipment of the M-III includes an auto-aperture for large and small focal spot exposures (large and small cassette holders) and separate fixed apertures for D-shaped spot and coned-down applications (Figure 2-1). Make sure an aperture is mounted properly, with its plastic face plate flush with the tubehead housing. The single-blade beam limiting device beneath the x-ray portal adjusts the rear edge of the fixed aperture beam pattern.

2.2

POWER-UP CHECKS After confirming the mechanical integrity of the M-1I1 unit and its cabling. connections accessories, place the circuit breaker above the power cord receptacle in the ON

and

---. Page 2-1

Revision - O.

LORAD

MEDICAL

M-III SERVICE MANUAL

SYSTEMS

AUTO-APERTURE

CONED DOWN APERTURE

SPOT APERTURE

Figure 2-1: M-III Apertures

Page 2-2

Revision - 0

LORAD MEDICAL

M-III SERVICE MANUAL

SYSTEMS

position. Press the POWER ON pushbutton on the DATAPORT control panel to turn the unit on. Verify that the unit powers up without tripping the circuit breaker. .

2.3

2.3.1

MENU/FRONT PANEL CONTROL CHECKS

Power-Up CRT Display

Upon turning the unit on, the DATAPORT screen will show the message "DIAGNOSTICS -- IN PROGRESS".

Within several seconds, the DATAPORT screen will change to "DIAGNOSTICS COMPLETE", along with an instruction to press the ENTER key to proceed.

When the ENTER key is pressed, the DATAPORT screen will change to its normal operation mode, with the Setup Table, the Exposure Control Line, and the Message Area. Any selectable modes, options, or parameters will have the same status as when the machine was previously turned OFF.

At the right side of the Exposure Control Line, the "Standby" indication will appear for a few seconds after power up and, if the radiation shield is open arid an aperture is installed, will be replaced by the "Ready" indication.

2.3.2

Cursor Key Function Use both CURSOR keys to verify that the DATAPORT screen cursor can be moved about the items in the Setup Table, and to and from the Exposure Control Line.

Use the CHANGE key to verify that selectable options in the Setup Table, for example EXP MODE, can be toggled from Manual to Auto-Time to Auto-KV, and that when in

Auto-KV, a target MAS value appears after the indication (80, 120 or 160 MAS). Confirm that the target MAS value agrees with the desired "window" for Auto-KV exposures (80 = 1.0 second "window"; 120 = 1.5 second "window"; and 160 = 2.0 second "window"). Enter the USER OPTION mode to change the target MAS value if necessary.

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LORAD MEDICAL 2.3.3

SYSTEMS

M-III SERVICE MANUAL

Entry Keypad Function Use the Cursor Keys to highlight the PATIENT 10 data line. Press the "C" key to clear the existing data, if any. Press the keys in the order 0-1-2-3-4-5-6-7-8-9, then press ENTER, and verify that 0123456789 appears as the PATIENT 10. Repeat this test using the Entry Keypad to enter 0123456789 as the TECH 10.

2.3.4

DateJTlmeClock The date and time should appear correctly in the Setup Table, as the Real Time Clock device is battery-backed. If the date and time are incorrect, correct them; then, turn the power off, wait a few minutes, and re-power. Confirm that the correct date and time are still shown on the screen when it is re-powered.

2.3.5

Exposure Control Keys

Use the Cursor Keys to select EXP MODE, then use the CHANGE key to select the Manual option. Cursor down to the Exposure Control Line. Use the KV UP and KV DOWN keys to display the kVp range of 22 to 39, in 1 kV increments, on the Exposure Control Line. Use the SECONDS UP and SECONDS DOWN keys to display the seconds range of 0.1 to 5.0, in .1 second increments, on the Exposure Control Line. .

Change EXP MODE to Auto-Time, and cursor down to the Exposure Control Line. Use the DENSITY UP and DENSITY DOWN keys to display the density adjustment range of -5 to +5 in Single integer increments. Repeat the Density adjustment test in Auto-KV mode.

2.4

2.4.1

C-ARM FUNCTIONAL

CH ECKS

C-Arm UP and DOWN Use the C-Arm UP and DOWN keys, located on each of the four 7-position keypads, and the 3-position keypad, to drive the C-Arm up and down. Confirm that the C-Arm drive stops automatically at its upper and lower limits, and that no error messages appear on the screen when any of the C-Arm UP/DOWN keys are pressed.

Page 2-4

Revision - B

LORAD MEDICAL 2.4.2

M-III SERVICE MANUAL

SYSTEMS

C-Arm Rotation A.

Rotation Release Confirm that with the power OFF and turned ON, the C-Arm's rotational position is fixed, and cannot be rotated until any of the C-Arm ROTATION RELEASE keys is pressed. Check that, when any ROTATION RELEASE key is let up, the C-Arm's rotational position is locked.

B.

C-Arm Angle DisplayUsing a_ROTATION RELEASE key, rotate the C-Arm from full counter-clockwise to full clockwise. At each detent position, verify that the proper angle is displayed on the LED arrays on both sides of the vertical cabinet, in addition to the DATAPORT screen. The detent positions are: -135

--~

2.5

-90

-45

o

+90

+135

+180

INTERLOCKS Three conditions will place the M-III into an interlock fault condition, where the "Ready" status indicator on the Exposure Control Line will be replaced by "Standby" until the condition has been cleared by the operator. When the M-III is in "Standby" status, exposure mode operation is disabled. When the status changes to "Standby" an appropriate error message will also appear in the Message Area of the DATAPORT screen.

2.5.1

C-Arm Safety Switch Press upward on the bottom end panel of the C-Arm and confirm- that the status indicated on the OATAPORT screen changes to "Standby". An error message will also be displayed in the Message Area. Check to confirm that the C-Arm DOWN keys are inoperative, but that the C-Arm UP keys still function to raise the C-Arm. Press the ENTER key to clear the error condition.

2.5.2

Aperture Interlock Pull the fixed aperture out from its seated position and confirm the status changes to "Standby", and the appropriate error message is displayed in the Message Area. Reseat the fixed aperture and confirm the 'return to "Ready" status.

Page 2-5

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LORAD MEDICAL 2.5.3

SYSTEMS

M-III SERVICE MANUAL

Door Interlock Verify that, with the door-like radiation shield opened out from the console, the status will indicate "Ready". Verify that closing the door against the console changes the status to "Standby".

2.6

ACCESSORY DETECTION AND RECOGNITION Testing the detection and recognition functions of the M-1I1requires that different accessories be mounted, and correct machine responses observed. The accessories necessary are:

1. 2. 3. 4. 5. 6. 7. 8.

LORAD Cassette Holder 18 x 24 centimeter; LORAD Cassette Holder 24 x 30 centimeter; LORAD Bucky Grid 18 x 24 centimeter; LORAD Bucky Grid 24 x 30 centimeter (optional); LORAD Magnification Tray; LORAD StereoLoc (optional); Piece of cardboard approximately 3/4" x 3" in lieu of items 5 and 6; Localization Tray (perforated 4-inch).

Image· Receptor Detection

2.6.1

Insert the 18 x 24/24 x 30 centimeter auto-aperture into the slide beneath the tubehead.

B.

c.

Slide an 18 x 24 centimeter cassette holder onto the image receptor tray. Using the Light Field, confirm that the aperture switches to the 18 x 24 size. Remove the 18 x 24 and mount a 24 x 30 centimeter cassette holder in its place. Using the Light field, confirm that the aperture switches to the 24 x 30 size.

Bucky Recognition

2.6.2

A.

Remove the 24 x 30 cassette holder and mount the 18 x 24 Bucky in its place.

B.

Confirm that the Setup Table GRID TYPE line indicates the Bucky is in place, and that the auto-aperture switches to the 18 x 24 size.

C.

Repeat the test using a 24 x 30 centimeter Bucky, if available.

Page 2-6

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LORAD MEDICAL

SYSTEMS

Mag Tray/Stereo

2.6.3

M-III SERVICE MANUAL

Detection

A.

Raise the compression device to its upper limit.

B.

Mount the Magnification Tray into the slots on the front of the C-arm.

C.

Confirm that the Setup Table indicates the presence of the Mag Tray, and that the Spot Size selection changes automatically to Small.

D.·

Remove the Mag Tray and install the StereoLoc in its place.

E.

Confirm that the Setup Table indicates the presence of the StereoLoc device, and that the Spot Size selection automatically changes to Large.

F.

If the StereoLoc device and Mag Tray are not available, this section of the M-III can be verified by using a srnall piece of cardboard to block the optical sensors just inside and below the left side Mag Tray slot. Blocking the front sensor will give the Mag Tray indications; blocking the rear sensor, or both sensors, will give the StereoLoc indications.

2.6.4

Localization Tray Recognition

A.

Remove the StereoLoc or Magnification Tray, lower the compression carriage, and mount a 4-inch perforated Localization Tray on the compression carriage.

B.

Confirm that the Setup Table RELEASE selection indicates "LOCKED OUT".

C.

Press one of the COMPRESSION compression carriage occurs.

D.

Remove the Localization Tray and install the 4-inch compression place.

E.

Confirm that the RELEASE selection does not change to "LOCKED OUT" .

RELEASE

keys; verify that no movement

of the

tray (no holes) in its

--

.

Page 2-7

Revision - 7

LORAD MEDICAL 2.7

M-III SERVICE MANUAL

SYSTEMS

COMPRESSION SYSTEM CHECKS

2.7.1

Motorized Compression Drive A.

Mount a LORAD Image Receptor on the image receptor tray. Mount a compression plate on the compression carriage.

8.

If necessary, "MANUAL".

C.

Using one of the COMPRESSION DOWN keys, drive the compression carriage down onto a rolled up towel placed on the image receptor.

D.

Confirm that the compression carriage stops automatically, and that no upward movement occurs after it stops. Check that the handwheels do not rotate (upwards) after the carriage stops.

E.

Press one of the COMPRESSION RELEASE keys, and verify that approximately 6 . centimeters of upward movement of the carriage occurs before the carriage automatically stops.

F.

Press one of the COMPRESSION UP keys to verify that the carriage moves upward while the key is depressed, and stops when the key is released.

G.

Repeat the above steps using all four sets of C-arm keypads.

2.7.2

change

the

DATAPORT's

COMPRESSION

RELEASE

selection

to

Manual Compression A.

Using a COMPRESSION DOWN key, run the compression plate down onto a rolled up towel on top of the image receptor.

8.

After the motorized compression drive stalls and stops, rotate the compression handwheel,

first slightly in the upward direction, and then downward against the towel. C.

Check that the handwheel turns hard in the upward direction, and easier in the downward direction. Confirm that, after turning the handwheel to apply more force, no upward slippage of the compression carriage occurs.

Page 2-8

Revision - 7

-~.

LORAD MEDICAL SYSTEMS Compression Thickness Display

2.7.3

A.

A.

With the compression device applying pressure to the rolled up towel, change the DATAPORT's RELEASE selection to Automatic, and change the EXP MODE to Manual. Set the exposure parameters for 0.1 second at 22 kVp.

B.

Close the beam depth slide completely, then step behind the protective radiation shield and press the X-RAY pushbutton to make an exposure.

C.

Confirm that, as the exposure ends, the compression carriage automatically moves upward approximately 6 centimeters and then stops.

FOOTSWITCHCHECK A.

2.9

With a Lorad image receptor in place on the image receptor tray, confirm that, as the compression carriage is moved up and down, using either the motorized mode or the manual handwheel, that the thickness between the top of the image receptor and the bottom of the compression accessory is displayed correctly in the Setup Table.

Compression Release Modes

2.7.4

2.8

M-III SERVICE MANUAL

Plug a footswitch into the jack provided and verify proper operation of Compression Up and Compression Down functions when the footswitch pedals are pushed.

PRINTER CHECK A.

Using the cursor keys, select the PRINTER line in the Setup Table and use the Change key to turn the printer "ON".

B.

Take an exposure and verify that all the correct information is printed upon its completion.

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X-RAY TUBE CURRENT CHECK The M-1I1selects and regulates x-ray tube current as a function of kVp. X-ray tube current can be checked as a voltage drop across a 10-ohm resistor on a small circuit board mounted on the terminal block directly behind the x-ray tube. The voltage drop across the resistor is proportional (a ratio of 1:100) to x-ray tube mA. The M-III has two regulated current settings (mA stations) for each focal spot, for a total of four. To check the tube current, perform the following steps. NOTE: Measuring the current requires the making of x-ray exposures.

2.10.1

mA Measurement Setup

1.

With the M-III power OFF, remove the top panel from the C-Arm to gain access to the measurement point.

2.

Connect a voltmeter across R42 on the Tube Control Board.

3.

Connect Channel 1 of a storage oscilloscope to the ungrounded end of the 10 ohm calibration resistor on the terminal block behind the tube head. Connect the probe ground to the other end of the resistor.

4.

Turn power ON, and press the ENTER key when instructed. Select option 1. "FILAMENT CALIBRATION" from the menu.

5.

The SMALL FOCAL SPOT - 22 kV DAC number will be displayed. Using kV UP/DOWN, preset the number to 100.

6.

Check the voltage on the meter connected across R42. It should read 0.5400 volts, indicating a standby current of 2.5 amps (.5400V + .22Q = 2.4 amperes).

7.

Disconnect the meter.

8.

Set the oscilloscope to acquire and store a single sweep.

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Set the scope controls as follows:

9.

10.

Trigger:

Channel 1

Vertical:

DC Volts 0.1/division (for Small Focal Spot tests) DC Volts 0.2/division (for Large Focal Spot tests)

Horizontal:

50 milliseconds, Single Sweep

Set the unit for 1 second, 22 kV, manual, small focal spot. Press the X-RAY button and examine the acquired waveform. An example of the ideal waveform is shown in Figure 2-2. A.

The waveform amplitude is 1/100 of the tube current. Fora 22 kV small focal spot exposure, the waveform should be 0.2 volts. Refer to Table 1 for voltages at the remaining kV/focal spot settings. If the waveform amplitude is below the specification, increase the DAC number, if the waveform amplitude is above the specification, decrease the DAC number. The DAC number is increased or decreased using the KV UP/DOWN keys.

B.

Examine the leading edge of the waveform for under- or over-shoot, as illustrated in Figures 2 and 3. The DAC number should be increased (to cure undershoot), or decreased (to cure overshoot) in small increments (usually 1 or 2).

C.

If the current measured is stable, but not at the specified level for the given spot size and kV, adjust R82 (mA Sense Cal) on the High Voltage Generator and try the shot again (CW lowers current; CCW raises current).

When current for the first kV has been calibrated, press the CLEAR key to move on to the next kV step, and continue as instructed above until all kV (up to 34) stations have been calibrated using both the LARGE and SMALL focal spots.

TABLE 2-1

kVp

25 31

mA

Large Focal Spot Voltage Reading

mA

80 70

0.8 volt 0.7 volt

20 17

Small Focal Spot Voltage Reading 0.2 volt 0.17 volt

READINGS THAT VARY PLUS OR MINUS 3% FROM THE READINGS SPECIFIED IN THE TABLE ARE ACCEPTABLE.

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SYSTEMS Note: Wave forms shown are for 80 mA. Adjust oscilliscope accordingly for other mA levels •

•1 See

.2 See

DACTOO LOW

.1 See

.2 See

DAC TOO HIGH

.1 See

.2 See

Figure 2-2: Waveforms Patterns

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TUBE VOLTAGE POTENTIAL CHECK

(Figure 2-3)

Checking Tube Voltage requires the use of a high voltage divider, a DVM, and a LORAD adapter cable to connect the divider to the test well on the M-III High Voltage Generator.

2.11.1

Tube Potential Check Procedure

A.

Ensure that system power is turned off. Remove the left and right side covers from the Control Console. Allow sufficient time for the high voltage capacitor to discharge. A neon bulb inside the generator cage indicates the charge condition of the capacitor; while the red bulb is glowing, the capacitor is charged to over 100 volts. Allow the red bulb to stop glowing, then wait five additional minutes before continuing.

B.

Connect a DC voltmeter to the low-voltage terminals of a 10,000:1 or 1,000:1 voltage divider, and position the meter where it can be read from behind the protective radiation shield.

C.

Connect the ground terminal of the voltage divider to the chassis ground stud (TP4) at the corner of the High Voltage Generator. Using the LORAD High Voltage Adapter, connect the free end of the high voltage divider test cable to the high voltage test well on the generator (Figure 2-3). Refer to Section 5 for instructions on accessing the generator.

D.

Close the beam depth slide in the beam limiting assembly completely, and turn the system ON.

E.

Set the system for a 2 second, 22 kV exposure in Manual mode.

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F.

While monitoring the meter from behind the protective radiation shield, press and hold the X-RA Y pushbutton to make an exposure.

G.

Confirm that the meter reading falls into the ranges below: 2.156 - 2.244 volts (using a 10,000:1 divider) 21.56 - 22.44 volts (using a 1,000:1 divider)

TEST WELL

H.V. POWER BOARD

H.V. CONTROL BOARD

Figure 2-3: High Voltage Generator Test Well

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H.

Set the system for a 2 second, ~kV

exposure in Manual mode.

I.

While monitoring the meter from behind the protective radiation shield, press and hold the X-RA Y pushbutton to make an exposure. \

J.

Confirm that the meter reading falls into the ranges below: 3.822 - 3.978 volts (using a 10,000:1 divider) 38.22 - 39.78 volts (using a 1,000:1 divider)

K.

2.12

Select intermediate kV settings, and confirm that the meter readings are within 2% of their kV settings divided by 10,000 (using a 10,000:1 divider) or divided by 1,000 (using a 1,000:1 divider).

AUTOMATIC

EXPOSURE CONTROL CHECK

Calibration of theAEC is performed at the factory to result in a consistent 1.2 density. Checking 'the AEC consists of making exposures using different combinations of acrylic phantoms and verifying consistent film density on the developed film. If it is necessary to readjust density to a different value to suit the user, refer to Section 8.4. The following items are necessary to verify AEC performance:

2.12.1

1.

Four 1-centimeter thick acrylic attenuators;

2.

One 4-centimeter thick acrylic attenuator;

3.

Film Densitometer;

4.

SO-177 Film and Min-R screen cassette.

AEC Check Procedure

A.

Place a loaded cassette under 4 centimeters of acrylic on the image receptor tray.

B.

Set the M-III for EXP MODE: AUTO-TIME and FILM TYPE: SO-177. Set the Exposure Control Line KVP to 25 KVP and DENSITY to O.

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C.

Make an exposure, then remove the cassette and develop the film.

D.

Measure the density of the developed

E.

Place the same loaded cassette under 1 centimeter of acrylic in position on the image receptor tray.

G.

Make an exposure, then develop the film and measure the density. Density should agree with the reading made in step 0, within ±O.2.

H.

Make exposures using the settings in the Table 2-2, and confirm that density results agree within ±O.2.

MODE AUTO-TIME AUTO-TIME AUTO-KV AUTO-KV 2.13

SYSTEMS

FILM SO-177 SO-177 SO-177 SO-177

film.

TABLE 2-2 FOCAL SPOT LARGE LARGE LARGE SMALL

KVP

25 25

CM.ACRYLIC

3 7

7 4

Bucky Grid Performance Check Checking the operation of the Bucky grid requires that the Bucky be mounted properly on the image receptor tray. Films must be exposed and developed during this test. It may be necessary to affix 2 centimeters of acrylic between the tubehead and the Bucky to ensure sufficient film density.

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A.

Make a 5-second exposure with the C-Arm rotated to -90 degrees (grid travel in the direction of gravitational pull) and verify the absence of grid lines in the developed film. (Acrylic attenuators may need to be secured to the top of the Bucky to give an adequate image.)

B.

Re-Ioad the cassette and make a 0.2 second exposure with the C-Arm rotated to +90 degrees (grid travel against the direction of gravitational pull) and verify the absence of grid lines in the developed film.

CHECKING HALF VALUE LAYER

This certification test measures the quantity of x-ray energy attenuated by passing through a specified filter. The test verifies the modification of x-ray tube performance by the filter in the LORAD x-ray tubehead. A.

Connect a 10-square centimeter x-radiation probe to its readout/logic module with a to-toot cable. Select Exposure in Milliroentgens on the instrument'S function switch.

B.

Position the compression tray 30 centimeters above the image receptor tray. Use fixturing to place the radiation probe 10 centimeters above the image receptor tray. Place the readout/logic module in a positioh where it can be read from behind the unit's radiation shield.

C.

Place a 1116-inch(1.6 mm) thick lead sheet with a cutout area 2.4-inch (6 em) in diameter on the compression tray.

D.

Turn the system ON and press the LIGHT FIELD pushbutton to illuminate the x-ray field. Limit the beam to approximately the size of the probe head, and adjust the positions of the probe and the cutout in the lead shield to center the radiation detector in the beam. Align the surface of the probe perpendicular to the beam axis.

E. .----- ..

Change the Setup Table options to EXP MODE: MANUAL and SPOT SIZE: LARGE. Set the Exposure Control Line selections to KVP: 30 KVP and EXP TIME: 1.0 Sec. Make an exposure and record the milliroentgen reading.

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F.

Cover the hole in the lead sheet with a 0.3 millimeter aluminum filter. Using the same technique factors as in Step E above, make another exposure and record the milliroentgen reading.

G.

Multiply the result obtained in Step F by 1.9. The product must be larger than the Step E reading.

CHECKING REPRODUCIBILITY and LINEARITY - MANUAL MODE The following tests verify that the x-ray system, including the controls and x-ray tube, is operating consistently. .

A.

Connect a 10-square centimeter x-radiation probe 1a-foot cable. Select Exposure in Milliroentgens on switch. Cover the top of the image receptor tray with place the probe upon it. Position the readout logic behind the machine's radiation shield.

B.

Turn the system ON. Illuminate the light field. Using the slide beneath the tubehead enclosure, limit the beam to .approximately the size of the probe head. Reposition the probe head to center its detector in the beam. Align the surface of the probe so that it stays perpendicular to the beam axis.

C.

On the screen Setup Table, select EXP MODE: MANUAL and SPOT SIZE: LARGE. Set the Exposure Control Line settings KVP to 25 KVP and EXP TIME to 0.6 Sec. Make an exposure and record the milliroentgen reading.

D.

Change the Exposure Control Line settings for both KVP and EXP TIME, then return them to 25 kVp and 0.6 seconds. Again, make an exposure and record the milliroentgen reading.

Page 2-18

to its readout logic module with a the readout logic module's function a 1116-inch (1.6 mm) lead sheet and module where it can be read from

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E.

Continue to randomly change the Exposure Control Line settings for KVP and EXP TIME. Then return to 25 kVp and 0.6 seconds. Make an exposure and record the milliroentgen reading. Repeat until ten individual readings have been obtained.

F.

Compute the average Milliroentgen reading. Subtract each actual reading from the average, and square each dltterence. Add the squares and divide the sum by 9. Then take the square root of the result.

G.

Divide the number calculated in Step F by the average milliroentgen reading to obtain the coefficient of variation. The coefficient of variation must be less than 0.05.

H.

Leave the setup on the image receptor tray unchanged, and change the Exposure Control Line KVP and EXP TIME selections to 25 KVP and 0.2 seconds, respectively. Make an exposure and record the milliroentgen reading and the mAs value displayed on the unit's control panel.

I.

Repeat Step H, changing the EXP TIME to 0.6, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, and 5.0. Record milliroentgens and mAs at each setting.

J.

K.

Divide each Milliroentgen reading by its corresponding

mAs value.

for each pair of successive tests (0.2 and 0.6 seconds; then 0.6 and 1.0 seconds; and so on), calculate the difference between each corresponding

Step J result.

L.

For each pair of successive tests, calculate the sum of each Step J result.

M.

Divide each Step K difference value by each Step L sum value. If the result for any pair exceeds 0.10, the test is considered failed.

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N.

RepeatSteps

O.

If the unit fails any part of the above test, first recheck all calculations, then repeat the tests (failure to meet these performance standards indicates trouble in the High Voltage Generator or x-ray tube).

CHECKING

H-M with the Small focal spot selected on the Setup Table.

REPRODUCIBILITY

and LINEARITY - AUTO-TIME MODE

.A.

Place a 4.3 centimeter acrylic phantom on an empty cassette on the image receptor tray. Position the 10 square centimeter x-radiation probe on top of the phantom. Align the probe position with the AEC sensor at front center on the image receptor tray, and using the light localizer, slide the beam limiting plate to just cover the probe.

B.

Change the Setup Table to BACKUP TIME: 3.0 Sec, EXP MODE: AUTO-TIME, and SPOT SIZE: LARGE. Set the Exposure Control Line, KVP to 25 KVP.

C.

Make ten exposures. Record milliroentgen and mAs readings for each one.

D.

The mAs readings should be in the range of 40 to 50; milliroentgen readings in the range of 850 to 900.

E.

Calculate the average Milliroentgen reading and subtract each actual reading from the average. Square each difference. Add the squares and divide their sum by 9. Then take the square root of the result.

F.

Divide the number obtained in Step E by the average milliroentgen reading. The quotient, called the coefficient of variation, must be less than 0.05.

G.

Remove the probe from the x-ray beam, leaving the acrylic and cassette on the image receptor tray. Change the Setup Table as follows: BACKUP TIME: 2.5 Sec and SPOT SIZE: LARGE. On the EXPOSURE CONTROL LINE, set KVP to 25.

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H.

Make an exposure and record the mAs value displayed.

I.

The mAs value should be in the range of 37 to 40.

CHECKING REPRODUCIBILITY and LINEARITY - AUTO-kV MODE

A.

Place a 4.3 centimeter acrylic phantom on an empty cassette on the image receptor tray. Position the 10 square centimeter x-radiation probe on top of the phantom. Align the probe position with the AEC sensor at front center on the image receptor tray, and using the light localizer, slide the beam limiting plate to just cover the probe.

B.

Change the Setup Table to BACKUP TIME: 3.0 See, EXP MODE: AUTO-KV, and SPOT SIZE: LARGE.

C.

Make ten exposures. Record Milliroentgen and mAs readings for each one.

D.

The mAs readings should be in the range of 40 to 50; milliroentgen readings in the range of 850 to 900.

E.

Calculate the averaqe Milliroentgen reading, and subtract each actual reading from the average. Square each difference. Add the squares and divide their sum by 9. Then take the square root of the result.

F.

Divide the number obtained in Step E by the average Milliroentgen reading. The quotient, called the coefficient of variation, must be less than 0.05.

G.

Remove the probe from the x-ray beam, leaving the acrylic and cassette on the image receptor tray. Change the Setup Table as follows: BACKUP TIME: 2.5 Sec and SPOT

SIZE: LARGE.

H.

Make an exposure and record the mAs value displayed.

I.

The mAs value should be in the range of 37 to 40.

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TIMING ACCURACY - MANUAL MODE The duration of the x-ray tube voltage timing pulse can be monitored on ari oscilloscope by measuring x-ray tube voltage as indicated at the low voltage terminals of a voltage divider or by measuring the duration of the KV SENSE analog signal. The first method is described in steps A through E and the second in steps F through J.

A.

Set up as described in Section 2.11, Tube Voltage Potential Check, but with an oscilloscope instead of the DVM on the low voltage terminals of the voltage divider.

B.

Close the single beam limiting plate completely and turn the M-III on. On the DATAPORT Setup Table, change EXP MODE to Manual and SPOT SIZE to Large. On the DATAPORT Exposure Control Line, set KVP to 25 and EXP TIME to 0.2.

C.

Press and hold the X-Ray button, and measure the width of the tube voltage waveform between the 80% voltage points. Record this time interval in seconds.

D.

Repeat step C with the EXP TIME set at 0.6, 1.0, 1.5, 2.0, 2-.5, 3.0, 3.5, 4.0, 4.5, and 5.0.

E.

Any measured exposure time that differs from the EXP TIME setting by more than 5% of the setting is cause for rejection.

F.

To use another method, connect an oscilloscope to terminal J207-3 (KV SENSE) on the Microprocessor board. Connect the oscilloscope ground to chassis ground, TP7.

G.

Close the beam limiting plate completely and turn the M-1I1on. On the DATAPORT Setup

Table, change EXP MODE to Manual and SPOT SIZE to Large. On the DATAPORT Exposure Control Line, set KVP to 25 and EXP TIME to 0.2.

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M-III SERVICE MANUAL

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H.

Press and hold the X-ray button, and measure the width of the tube voltage waveform from the +5 volt pulse. The voltage at J207-3 rises to about 5 volts when kV in the x-ray tube circuit reaches about 80% of kVp setting. Record this time interval in seconds.

I.

Repeat the test at the exposure times listed in steps D and E. Any measured exposure time that differs from the EXP TIME setting by more than 5% is unacceptable.

MAXIMUM mAs in AUTO-TIME MODE

A.

Move the beam depth slide all the way forward (away from the c-Arrn) to block off the

x-ray beam. Place a lead shield on the image receptor tray over the AEC Sensor in the front center of the tray. Change the Setup Table SPOT SIZE: Large.

B.

Change Setup Table options Exposure Mode to Auto-Time, Backup Seconds to 5.0, Spot Size to Large, and Film Type to OM. On the Exposure Control Line, set KVP to 22 and DENSITY to +5.

C.

Make an exposure and read mAs calculated on the Exposure Control Line at the end of the exposure time.

D.

Indicated mAs should be 400.

E.

Error messages: "X-Ray Button Fault" and "Backup Timer" should appear at the bottom of the screen. It must be impossible to conduct another exposure before resetting the unit using the Enter key.

F.

Repeat the test with kVp set to 35. The mAs reading at the end of the exposure should be 300.

G.

Uncover the AEC Sensor and open up the beam depth slide to include the sensor in the x-ray beam. Change Setup Table options, BACKUP TIME to 5.0, EXP MODE to AUTOTIME, and FILM TYPE to OM. Also set the Exposure Control Line KVP to 25 and DENSITY to -5.

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Conduct an x-ray exposure. The mAs calculated at the end of the exposure should be a very small number, and it must be less thanS.O.

CHECKING the X-RAY SHIELDING of the IMAGE RECEPTOR TRAY To minimize stray radiation, the x-ray tube housing is shielded with lead, as is the inside of the lower LORAD tubehead enclosure. Lead shielding is also incorporated within the image receptor tray and behind the AEC sensor. Shielding performance is checked with the following procedure.

A.

Connect a 100 square centimeter radiation scatter probe to the readout/logic module of a radiation ratemeter. Select EXPOSURE IN MILLIROENTGENS as the operating mode. Place the probe on a lead-covered adjustable stand positioned beneath the image receptor tray, and place the readout/logic module so it can be read from behind the protective radiation shield.

B.

Attach a 18 x 24 cassette holder to the image receptor tray and change Spot Size to Large. Place a 1/16-inch (1.6 mm) sheet of lead with as-inch (12.7. cm) diameter hole in it on the image receptor tray. Slide this lead sheet to position the hole at the position marked "A" in Figure 2-4. Illuminate the light field and adjust the beam limiting slide to closely correspond to the hole.

C.

Line up the probe beneath the tray in the center of the x-ray beam path through the hole in the lead sheet. Raise or lower the support stand until the probe is exactly S centimeters (1-31/32 inches) below the bottom of the tray structure. Face the probe's detector surface toward the x-ray source.

D.

Turn the x-ray system ON, and change Setup Table options SPOT SIZE: LARGE and EXP MODE: MANUAL. Set the Exposure Control Line selections KVP to 39 and EXP TIME to 3.0 Sec.

E.

Make an exposure and record the mR reading.

F.

If the reading exceeds 0.10 mR, corrective action is indicated.

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24X 30 em HOLDER

TRAY

/

',;t'------H---,

/

,,

, , '

, ,,

,

,, ,,

-,

.

.•. __

,r

..

, , "

"

';I:.•..

--

,,

,,

,, ''

E

.

..".,.:

',

A

•...._--_B ..

r

, ' ",;< .

F _,' ---_ .....

Figure 2-4: Image Receptor Tray Test Points

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2.21

-----..~ 2.22

MEDICAL SYSTEMS

M-III SERVICE MANUAL

G.

Repeat steps 8 through F at the positions marked "8", "C", and "0" in Figure 2-4.

H.

Mount a 24 x 30 centimeter cassette holder on the image receptor tray. Repeat steps 8 through F at the positions marked "E", "F", "G" and "H" in Figure 2-4. Readings above 0.10 mR indicate replacement of the cassette holder is necessary.

CHECKING THE X-RAY SHIELDING OF THE TUBEHEAD A.

Using the 1co-square centimeter radiation scatter probe and radiation ratemeter described in the previous procedure, change ratemeter mode to mR/HOUR. Set up an adjustable stand to hold the probe in position with relation to the tubehead as shown in Figure 2-5.

8.

Position the probe at each of the locations "A" through "H" shown in the figure (for position "H", rotate the C-Arm so the probe can be positioned directly behind the tubehead). For each position, the distance between the probe and the tubehead surface must be maintained at exactly one meter.

LIGHT FIELD

2.22.1

Light Field illuminance Test Intensity and consistency procedure.

of the Light Field is checked by performing

the following

A.

Insert the auto-aperture into the slot below the tubetiead. Slide the beam depth slide all the way back (towards the C-arm).

8.

Place a light meter probe on the image receptor tray with its sensor facing up.

C.

At each location shown in Figure 2-6, take a background light reading (Light Field lamp OFF), and another one with the Light Field lamp ON.

O.

For each location (quadrant), convert both the background and lighted readings to lux values (use the conversion table on the meter or in the meter manual), and subtract background lux from Light Field lux.

E.

If the difference in any quadrant is less than 200 lux, the Light Field Illuminance Test is considered failed.

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A-

H

/

F

B

E

G

Figure 2-5: Tubehead Test Points

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MEDICAL SYSTEMS

C

D

A

B

Image Receptor Tray (Top View)

Figure 2-6: Light Field Test Areas

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M-III SERVICE MANUAL

Light Field Alignment Certification

To perform this test, the following equipment will be necessary: 1. 2. 3.

24 x 30 centimeter cassette and film; Straight pieces of wire or solder; Front Loading 24 x 30 cm cassette holder.

A.

Place a loaded 24 x 30 centimeter cassette into a 24 x 30 centimeter front loading cassette holder mounted to the image receptor tray.

B.

Insert the Coned-Down Spot Aperture (Figure 2-7).

C.

Turn the Light Field ON. Move the beam depth slide all the way back to project the lighted area pictured in Figure 2-8.

D.

Using straight pieces of wire or solder, accurately mark the outline of the light field on the cassette surface.

E.

. Change the DATAPORT Setup Table, EXP MODE to MANUAL and SPOT SIZE to LARGE. On the DATAPORT Exposure Control Line, set kVp to 22 and EXP TIME to 0.6.

F.

Step behind the radiation shield, and press and hold the X-Ray button. Remove the cassette and develop the film. Compare the edges of the image area with the w hit e marks caused by the pieces of wire or solder. All boundaries must coincide within 1.3 centimeters (0.51 inch).

G.

If the Light Field borders are more than one centimeter away from the x-ray beam, adjustment per Section 6.4 is indicated.

. -.--........,

.:""

FILAMENT CURRENT FEEDBACK

....J ~5

MAIN COMMON

MOTOR CONTROL

PHASE

J311

1

3

FILSENSE (MICROPROCESSOR ERROR CONTROL)

H.V. GENERATOR

.11

3

J30S

POWER CONTROL BOARD

Figure 3-6: Filament Control Signals

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SYSTEMS

MA SENSE Analog signal proportional to actual tube current developed at U2 of the High Voltage Generator as measured across a resistor in the multiplier of the High Voltage Generator. The signal leaves the High Voltage Generator at J1-5 and enters the microprocessor at J207 -5. The signal is applied to multiplexer U38 and passed through U39, which limits the signal to 10 volts maximum. Analog to digital converter U40 passes the tube current information to the data bus.

D.

LARGE Digital signal that enables the selected tube filament; latched from data bus by U30 and exits the microprocessor via J206-27.

E.

FIL EN Digital signal that enables filament current regulation by the Tube Control Board; latched from data bus by U30 and exits the microprocessor via J206-29.

Tube current in the M-III is regulated by means of a flyback regulator on the Tube Control Board consisting of transformer T1 and FET 09. The gate of FET 09 is driven by the output of pulse width modulation controller U12. The pulse width controller is supplied with operating power by a circuit consisting of 02, 04, and associated components. The 14 volt switched supply is derived from the + 16 volt DC input to the Tube Control Board from the Power Control Board. The 14-volt supply is only switched on when the FIL EN signal from the microprocessor has switched high.

3.4.4

Filament Regulation One side of the T1 primary is connected to the +16 volt motor supply voltage from the: Power Control Board. The other side of the primary is tied, through the FET and .

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resistor R6S, to ground. The U12 square wave output, switching current through the highly inductive T1 windings, creates a secondary current flow, which is passed through diode OS and is filtered by capacitor C29. The resulting filament drive signal is a smooth modulation, with a DC offset. Coupled to the selected filament through contacts of relay K1, the signal results in the large or small filament selection. Relay K1 is driven, through transistor 05, by the microprocessor output signal LARGE, which is high when the large spot is selected, low for the small spot.

The filament current is sensed across resistor R42, and applied to filament current sense differential amplifier U2:The U2-8 output is applied to another section of U2, which buffers the amplified current sense signal before it is sent to the microprocessor. The U2-8 output is also applied to a third section of U2, at pin 5, which acts as an error amplifier. The analog FIL CUR signal, which the processor generates as determined by thekVp setting, is buffered through a fourth section of U2 and is applied to the inverting input of the error amplifier. The output of the error amplifier is proportional to the difference between the FIL CUR command from the microprocessor and the actual filament current as sensed across R42.

The error voltage output of U2-7 varies the pulse width output of U12, which, by driving the gate of 09, varies the operation of the flyback converter to provide the current required by FIL CUR command signal.

If the current output from the T1 secondary exceeds safe limits, the LED in opto-isolator US is turned on through resistor R45. Likewise, if the voltage output at the T1 secondary exceeds safe limits, zener diode 011 (when the large spot is selected) or 010 (when the small spot is selected) will reach the avalanche point and turn on the LED of opto-isolator US. When US has been turned on, the 14-volt supply to the pulse width controller is shunted to ground through SCR 03.

3.5

HIGH VOLTAGE GENERATOR (Figure 3-S)

The isolation transformer supplies power at 220 volts and line frequency to the High Voltage Generator. This input is fused at 10 amperes. A full-wave bridge rectifier and a 3300-microfarad capacitor supply a nominal 300-volt DC bus voltage to a high frequency inverter bridge, which converts the DC to a high frequency AC signal applied to the high-

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MEDICAL SYSTEMS

voltage transformer modulator.

and multiplier.

The high-frequency

AC is controlled

by a pulse width

If the AC input voltage to the generator exceeds 400 volts, an arc fault latch terminates system operation and a red LED lights on the High Voltage Generator Control Board. If the DC bus voltage exceeds 400 volts, an overclamp fault latch terminates operation (another red LED lights on the same board). Excessive current output from the inverter bridge drive signals an overcurrent fault clamp and a yellow LED lights on the High. Voltage Control Board. A fourth (green) LED lights to indicate that the XRA Y1 interlock has occurred (X-RAY button is pressed).

The 220-volt input also powers the high voltage generator's on-board regulated 15-volt DC control power supply. This voltage source provides the input power to the generator's fault latches (therefore, enabling or disabling the system), and input power for the HV ENABLE, HV FAULT, and RESET signalling circuits (also enabling or inhibiting system operation).

For the generator to operate, the circuit that passes the 15-volt signal from the X-RAY pushbutton must be closed; a closed circuit between interlock signals XRA Y1 and XRA Y1 RT must exist (generator connector, J320-25 and J320-26). The circuit closure is provided by an interlock relay, K1, on the microprocessor. With a path closed between these signals, the output of the 15-volt regulator, U3, is routed to the pulse width modulator on the High Voltage Generator. Before exposure, the microprocessor developed signal, RESET, checks three times in 50-millisecond intervals for startup errors detected through generator signals KV SENSE, MA SENSE, and HV FAULT. Any problem in these circuits will disable the pulse width modulator, and the HV FAULT signal is sent to the microprocessor. After confirming that no fault conditions exist, the microprocessor checks for an active high at ROTOR OK.

With no system faults detected and ROTOR OK present, an HV ENABLE signal starts the generator. The high voltage DC output is determined by the analog KV CNTL reference signal input. There is' a delay of six milliseconds for the High Voltage Generator to reach the selected kV. After the six milliseconds, the microprocessor begins to time the exposure and waits another six milliseconds to check KV SENSE which measures achieved voltage. The pulse width modulator of the High Voltage Control Board then adjusts output voltage through a comparison of the KV CNTL signal .

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M-III SERVICE MANUAL

MEDICAL SYSTEMS

J325-1

1 ~~~

J325-4

4

I

I-

T3

BR1 I-

'---

'---

U3

-

0

*_

A

l.....-

D33

r---

J320-1

-

I FEED FWD·1

T1

D36 :.--

-

RaO"!,,

-

t

300VDC

f--

I--

to

'---

TO X-RAY TUBE

TP4

~

r---

X-RA Y INTK ..1320-25

YYV

T U5 PWM

f--

T1,L3,U1,K1 DC/AC INVERTER

~

f..-

T2 HV XFMR

~ f.-

HV MULTIPLIER

cr~ R20

KVCNTL

..1320-26 X-RAY INTK RT

.•. TP15 FEEDBACK INHIBIT

..1322-7 ~

KVSENSE

..1320-3 _

MASENSE

..1320-5""

..1320-11 HV FAULT _J320-15

HV ENABLE

..1320-21 RESET

U6,U7, Ua,U9 FAULT LATCHES

J320-12 ROTOR OK

Figure 3-8: High Voltage Generator Control Signals

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M-III SERVICE MANUAL

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and a FEEDBACK signal from the high voltage multiplier circuit of the generator. The KV CNTL signal is 1 volt for 22 kV and increases .5 volt per kV to 7.0 volts for 34 kV. As long as high voltage output is within ±12% of the value commanded by the KV CNTL signal value, the HV ENABLE signal is output from the microprocessor. Output high signals from the Microprocessor to the generator are 10 volts; low signals are zero. The signals that correspond to the generator output for x-ray exposure are as follows.

MA SENSE

MPU(J207-5)

OV

= =

10 V

-

HVG(J320-5)

KV SENSE

MPU(J207-3)

HVG(J320-3)

o mA

OV

=

100 mA

10 V

=

o kV 40 kV

KV CNTL

MPU(J207-1)

OV

=

10 V

3.6

HVG(J320-1)

AUTOMATIC

20 kV 40 kV

EXPOSURE CONTROL CIRCUIT

(Figure 3-9)

The Automatic Exposure Control System is comprised of an AEC Sensor Board, located within the image receptor tray, circuits on the Microprocessor Board, which condition the signal input from the Sensor Board, and algorithms contained in the system's operating program.

3.6.1

AEC Sensor

Board

The Sensor Board uses a silicon photodiode to collect incident x-ray photons which penetrate the patient's tissue, the film cassette, the film, and the light-tight cover of the photodiode itself. The photodiode converts the x-ray photons into an electrical current which is proportional to the incident radiation. This current is amplified by a high gain (approximately x560 million) amplifier, U1, and sent to the Microprocessor Board over a shielded cable.

------

The AEC Sensor Board is powered Microprocessor Board. The Sensor

by +15 and -15 volt D.C. power

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M-III SERVICEMANUAL

MEDICAL SYSTEMS

Board is mounted on a slide mechanism, permitting the operator to move it longitudinally within the image receptor tray. Its position is sensed through a series of three optical switches, and displayed on one of three LEDs mounted on each 7-switch C-Arm control panels.

3.6.2

AEC Signal Path - Microprocessor Board Entering the Microprocessor Board at J202-5, the amplified sensor signal (AEC_SIG) is scaled by a potentiometer (R40) and sent through a low-pass filter, consisting of an element of RN14 and C63, to eliminate high frequency noise. The Signal then is passed through analog mulitiplexer U38, clamped to 10 volts by U39, and applied to a precision 12-bit analog to digital converter. Here, the analog signal is converted to the digital domain and placed on the data bus for further processing.

3.6.3

AEC Signal Processing . The software samples the sensor signal and numerically performs a low-pass filtration and differentiation. Once the signal has stabilized, it is input to a second order equation to calculate the ideal exposure time. The characteristics of this equation are based on kV, focal spot size, film type, accessories detected, and the density setting. This calculation cycle can take from 5 ms to 50 ms depending on the magnitude of the detector signal. This is because smaller signals produce longer exposures and have longer rise times.

Two software adjustments permit tailoring of the AEC Signal to a particular film/screen combination. GAIN scales the AEC signal; OFFSET adds a voltage factor to the signal. GAIN and OFFSET software adjustments are available for each film/screen combination.

3.6.4

AUTO-TIMEMode Exposure Termination Once the ideal exposure time has been determined, the machine waits until the actualexposure time reaches the ideal exposure time and then terminates the exposure cycle. If the ideal exposure time exceeds the operator selected "BACKUP TIME", the exposure will be terminated when the time reaches the "BACKUP TIME".

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AUTO-KV

SYSTEMS

M-III SERVICE MANUAL

Mode Exposure

Termination

With AUTO-KV selected, a maximum exposure window of 1, 1.5 or 2 seconds (selected prior to the exposure by the operator) controls automatic kV adjustment. The AUTO-KV mode functions in a similar manner to AUTO-TIME until the Microprocessor determines, through the calculation cycle, that the ideal exposure time exceeds the "window". If and when this situation occurs, the Microprocessor increases the KV level from 25, to 26, 27 or 28 kV, whichever is appropriate to complete the exposure within the "window". If it is necessary to change the KV level, the change will occur approximately 40 milliseconds into the exposure. After the kV level is increased, the machine waits an additional 40 ms for tube current to stabilize. The calculation cycle is repeated to find the new ideal exposure time which will be equal to or less than the "window". If the initial calculation cycle has resulted in a KV level increase to the maximum of 28 kV, the new ideal exposure time may exceed the "window", but the conditions that would cause this to happen would be very unusual.

BREAST TRAY

X.RAYS

AEC DETECTOR

+15V

?

~

·15V (

r " ...... ,

:

I I

I-

~~

I

I

f4l 3

I

I

I

~2

1

2

..

~•..

4

3

I

MICROPROCEssOR

I--

AID U40

J'--

4

o

L 0 G I C

'[I

+15V ·15V

AGNO

l-

Fl

MULTI· PLEXER U38

"t"

~1

/-,

5

I I

I I

..•

AECSIG

I

2

I I

I

4

I I I

..

·15V

~I I

R40 R44

" AGNol

--

"

I-

1

~'-

+15V

AGNO

1

~

w DGNOt

Figure 3-9: Automatic Exposure Control Signals

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LORAD MEDICAL 3.7

SYSTEMS

M-III SERVICE MANUAL

INTERLOCK CIRCUITS (Figure 3-10) There are three interlock circuits in the M-lii. Unless all three interlock circuits are satisfied, the machine status will remain in "Standby" and exposure operation will be disabled. When all three interlocks are satisfied. "Ready" status will be resumed, providing that no system electrical problems are detected by the microprocessor. The M-III interlock circuits and the conditions that satisfy them are explained below.

3.7.1

Radiation Shield Interlock The common contact of switch S101 that is actuated by the opening of the radiation shield, is supplied 5 volts from the Microprocessor Board at J213-1. The normally open contact of the switch is connected to the microprocessor at J213-5 (signal name: DOOR_I NT). When the switch is closed by the shield, a zero to 5- volt transition of the DOOR_INT Signal occurs.

3.7.2

c-arm Safety Switch The spring-loaded panel at the bottom end of the C-arm must remain unobstructed during operation. The series switch circuit is closed and is supplied 5 volts from the common contact of S101 (Radiation Shield Interlock switch). The other end of the series switch circuit is applied to the Microprocessor Board at J213-5 as the signal ACT_OK. Should the panel encounter an obstruction, one of the two series-wired normally-closed switches becomes actuated. When the switch is opened by the disturbance of the panel, a 5 to 0 volt transition of the ACT-OK signal occurs.

3.7.3

Aperture Interlock In the Beam Limiting Assembly, at the inside end of the fixed aperture slide. an optical switch is positioned so as to be interrupted by a tab on the fixed aperture. Power to operate the LED within the optical switch comes from the Auto Aperture Board J441-3. When an aperture is in place, J204-14 of the Microprocessor Board is pulled high at the microprocessor by resistor network RN11. When the aperture is removed. J204-14 is pulled low by the optical switch in the Beam Limiting Assembly.

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M-III SERVICE MANUAL

MEDICAL SYSTEMS

+5V ~

-~

5

5101.L

OOORINT.

"-

U4

L 0 G I C

~