Hologic Discovery Technical Manual
DISCOVERY
™
QDR® Series
FAN BEAM X-RAY BONE DENSITOMETER
TECHNICAL MANUAL
Hologic, Inc.
35 Crosby Drive
Bedford, MA 01730
USA
Phone in US: 800-321-4659
Fax (Domestic): 781-280-0670
Fax (International): 781-280-0671
Document 080-1085
Revision 008
Discovery QDR Series Technical Manual
December 2010
Notice
The information contained in this manual is confidential and proprietary to Hologic, Inc.
This information is provided only to authorized representatives of Hologic's customers
solely for the purpose of facilitating the use of Hologic's products. No information
contained herein may be disclosed to any unauthorized person for any purpose whatsoever
without the prior written consent of Hologic, Inc.
The procedures described in this document are intended for use by direct employees of
Hologic, Inc., or authorized Hologic Equipment Resellers and their trained field
engineers. Any unauthorized or untrained persons performing these procedures may affect
the warranty of the Discovery QDR Series.
Exercise proper caution when servicing the system. There are dangerous and potentially
lethal voltages accessible within the Discovery system. To avoid exposure to shock
hazards, the Main Circuit Breaker should be switched off, and the power cord removed,
before working inside any part of the system.
The Discovery QDR Series Fan Beam X-ray Bone Densitometer produces ionizing
radiation in the form of X-rays. It may be dangerous to the patient, operator or field
engineer unless safe exposure factors and operating instructions are observed. To avoid
unsafe exposure, do not attempt to service the equipment unless you are a Hologic, Inc.,
certified field engineers. Exercise proper caution when servicing the system. A dosimeter
(film badge) should always be worn while on site. Dose and scatter measurements must be
taken after each service call to ensure that the parameters are still within specifications.
Hologic, Inc., has made all effort to ensure that the information in this manual is accurate
and complete. Hologic, Inc., shall not, however, be liable for any technical or editorial
errors or omissions contained herein, or for incidental, special or consequential dangers in
connection with the furnishing or use of this manual. The information in this manual is
subject to change without notice.
Discovery and the Hologic logo are registered trademarks of Hologic, Inc. All other
products and company names used in this manual are trademarks and registered
trademarks of other manufactures.
Printed in U.S.A.
Copyright© 2003-2010 by Hologic, Inc., All rights reserved
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Discovery QDR Series Technical Manual
Chapter 1 -
INTRODUCTION
1.1 System Overview ............................................................................................... 1-1
1.1.1 X-Ray Scanning Principles ....................................................................... 1-2
1.2 Functional Overview .......................................................................................... 1-4
1.3 Product Specifications ..................................................................................... 1-10
1.3.1 Exam Mode(s) Performance ................................................................... 1-12
1.3.2 Duty Cycle: ............................................................................................. 1-13
1.3.3 Leakage Technique Factors .................................................................... 1-13
1.3.4 Minimum Beam Filtration ...................................................................... 1-13
1.3.5 Measured Half Value Layer (HVL) At Different Operating Potentials . 1-13
1.3.6 Line Voltage and Maximum Line Current ............................................. 1-13
1.3.7 Technique Factors for Maximum Line Current ...................................... 1-13
1.3.8 Maximum Deviation ............................................................................... 1-14
1.3.9 Measurement Criteria for Technique Factors ......................................... 1-14
Chapter 2 -
FUNCTIONAL DESCRIPTION
2.1 Computer ........................................................................................................... 2-1
2.2 PCI Communications Controller Board ............................................................. 2-1
2.2.1 Interface Connections ............................................................................... 2-1
2.3 Distribution Board ............................................................................................. 2-3
2.3.1 Power ........................................................................................................ 2-3
2.3.2 Interface Connections ............................................................................... 2-4
2.4 Motor Controller Board ..................................................................................... 2-5
2.4.1 Power ........................................................................................................ 2-5
2.4.2 Interface Connections ............................................................................... 2-6
2.5 TZ Drive Board (A and SL Only) ...................................................................... 2-6
2.5.1 Service Switches ....................................................................................... 2-7
2.5.2 Power ........................................................................................................ 2-7
2.5.3 Interface Connections ............................................................................... 2-8
2.6 Control Panel Controller Board ....................................................................... 2-10
2.6.1 Power ...................................................................................................... 2-10
2.6.2 Interface Connections ............................................................................. 2-10
2.7 C-Arm Interface Board .................................................................................... 2-12
2.7.1 Continuity Daisy Chain .......................................................................... 2-13
2.7.2 Power ...................................................................................................... 2-13
2.7.3 Interface Connections ............................................................................. 2-13
2.8 X-Ray Controller Assembly (P/N 010-1273) .................................................. 2-16
2.8.1 Interface .................................................................................................. 2-16
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Discovery QDR Series Technical Manual
2.8.2 X-Ray Controller Board .......................................................................... 2-18
2.9 X-Ray Source Unit ........................................................................................... 2-19
2.10 Data Acquisition System (C, W, and SL) ..................................................... 2-20
2.10.1 Solid State Detector ............................................................................. 2-20
2.10.2 Integrator/Multiplexor Subsection ........................................................ 2-20
2.10.3 Analog To Digital Board ...................................................................... 2-21
2.10.4 Power .................................................................................................... 2-21
2.10.5 Interface Connections ........................................................................... 2-21
2.11 Data Acquisition System (A Model only) ..................................................... 2-23
2.11.1 Solid State Detector ............................................................................. 2-23
2.11.2 Power .................................................................................................... 2-23
2.11.3 Interface Connections ........................................................................... 2-23
2.12 Integrator/Multiplexor Board ......................................................................... 2-24
2.12.1 Power .................................................................................................... 2-25
2.12.2 Interface Connections ........................................................................... 2-25
2.13 Analog To Digital Board (A Model Only) .................................................... 2-27
2.13.1 Power .................................................................................................... 2-27
2.13.2 Interface Connections ........................................................................... 2-27
2.14 Torroid Power Module and DIN Rail ............................................................ 2-29
Chapter 3 -
INSTALLATION
3.1 Pre-Installation Requirements ............................................................................ 3-1
3.1.1 Required Tools .......................................................................................... 3-1
3.1.2 Required Documentation .......................................................................... 3-1
3.1.3 Room and Doorway Size .......................................................................... 3-2
3.1.4 Arrange For Help ...................................................................................... 3-6
3.2 Uncrate and Move to Destination ...................................................................... 3-6
3.2.1 Inspect For Shipping Damage ................................................................... 3-6
3.2.2 Uncrate Unit .............................................................................................. 3-7
3.2.3 Take Inventory .......................................................................................... 3-8
3.2.4 Measure Path To Final Destination .......................................................... 3-8
3.2.5 Remove Tabletop (If Necessary) .............................................................. 3-9
3.2.6 Remove Discovery A or SL Lower C-Arm Assembly (If Necessary) ... 3-10
3.2.7 Prepare the Tabletop for Moving (A, W,Wi) .......................................... 3-12
3.2.8 Move Unit To Destination ...................................................................... 3-12
3.2.9 Set Up the Unit ....................................................................................... 3-16
3.3 Install the System ............................................................................................. 3-18
3.3.1 Install Cables ........................................................................................... 3-18
3.3.2 Check Power Line Voltage ..................................................................... 3-23
3.3.3 Install Computer ..................................................................................... 3-24
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Discovery QDR Series Technical Manual
3.3.4 Start QDR Software in Service Mode ..................................................... 3-24
3.3.5 Check Table Alignment .......................................................................... 3-25
3.3.6 Perform C-Arm Parallelism Adjustment (A and SL systems only) ........ 3-27
3.4 Calibrate and Test the System ......................................................................... 3-28
3.4.1 Check Tube kV Peak Potential ............................................................... 3-28
3.4.2 Check Tube Current ............................................................................... 3-30
3.4.3 Adjust Belt Tension ................................................................................ 3-32
3.4.4 Calibrate Motors ..................................................................................... 3-33
3.4.5 X-Ray Beam Alignment ........................................................................ 3-47
3.4.6 Calibrate Aperture (Cannot be run on Ci and Wi models) ..................... 3-53
3.4.7 Check Laser Positioning Offset .............................................................. 3-54
3.5 A/D Gain Control Adjustment ......................................................................... 3-54
3.5.1 Check and Verify the A/D Gain ............................................................. 3-54
3.5.2 Adjust the A/D Gain ............................................................................... 3-55
3.5.3 Perform Detector Flattening .................................................................. 3-55
3.5.4 Perform Lateral Alignment Test (A and SL) .......................................... 3-56
3.5.5 Check HVPS/S (Tank) For Radiation Leakage ...................................... 3-58
3.5.6 Calibrate For Area, BMD And BMC ...................................................... 3-60
3.5.7 Scan Thickness Measurement & Calibration (C and W) ........................ 3-61
3.5.8 Scan Thickness Measurement & Calibration (A and SL) ....................... 3-61
3.5.9 Calibration of Area and BMC, for Array Scan Modes ........................... 3-62
3.5.10 RECALYZE and Add Array AP Scans to the QC Database ................ 3-63
3.5.11 Install Software Options ....................................................................... 3-64
3.5.12 Test Scan Modes ................................................................................... 3-64
3.5.13 Finish Assembling Unit ........................................................................ 3-66
3.5.14 Measure X-Ray Dose To Patient .......................................................... 3-66
3.5.15 Measure X-Ray Scatter From Phantom ................................................ 3-67
3.5.16 Perform QC ........................................................................................... 3-67
3.5.17 Run Reproducibility Test ...................................................................... 3-67
3.5.18 Table Top Radiographic Uniformity (A, W and Wi) ........................... 3-68
3.5.19 Instruments using Body Composition Analysis (BCA) ........................ 3-69
3.5.20 Instruments using BMD Whole Body Analysis ................................... 3-70
3.6 The Radiation Measurement Report ................................................................ 3-70
Chapter 4 -
ALIGNMENT AND CALIBRATION
4.1 Check Table Alignment ..................................................................................... 4-1
4.2 Align the Table .................................................................................................. 4-1
4.2.1 Table Edge to T-Rail (“A” Dimension) Adjustment ................................ 4-1
4.2.2 Front to Back T-Rail and Table Edge/Rail Gap Adjustment .................... 4-3
4.3 C-Arm Parallelism Adjustment ........................................................................ 4-3
4.4 X-Ray Beam Alignment ................................................................................... 4-4
4.5 Aperture Calibration ......................................................................................... 4-9
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Discovery QDR Series Technical Manual
4.6 Motor Calibration ............................................................................................ 4-10
4.7 Laser Positioning Offset Adjustment ............................................................... 4-26
4.8 A/D Gain Control Adjustment ......................................................................... 4-26
4.8.1 Check and Verify the A/D Gain ............................................................. 4-27
4.8.2 Adjust the A/D Gain ............................................................................... 4-27
4.9 Filter Drum Encoder Alignment ...................................................................... 4-28
4.10 Detector Flattening ....................................................................................... 4-29
4.11 Lateral Alignment Test (QDR 4500A and SL) .............................................. 4-30
4.12 Table Top Radiographic Uniformity ............................................................. 4-32
4.12.1 Instruments using Body Composition Analysis (BCA) ........................ 4-33
4.12.2 Instruments using BMD Whole Body Analysis ................................... 4-33
4.13 Check Phantom values ................................................................................... 4-34
4.14 Area, BMD, and BMC Calibration ................................................................ 4-34
4.14.1 Scan Thickness Measurement & Calibration (C and W) ...................... 4-35
4.14.2 Scan Thickness Measurement & Calibration (A and SL) ..................... 4-36
4.14.3 Calibration of Area and BMC, for Array Scan Modes ......................... 4-37
4.14.4 RECALYZE and Add Array AP Scans to the QC Database ................ 4-38
Chapter 5 -
REMOVE AND REPLACE PROCEDURES
5.1 Recommended Tools ......................................................................................... 5-1
5.2 Electronics Tray FRUS ...................................................................................... 5-1
5.2.1 Electronics Tray Printed Circuit Boards ................................................... 5-2
5.2.2 C-Arm Y Motor or Gearcase .................................................................... 5-3
5.2.3 C-Arm Y Encoder ..................................................................................... 5-4
5.3 Table Y FRUs (A, W and Wi Only) .................................................................. 5-4
5.3.1 Control Panel (All models) ....................................................................... 5-5
5.3.2 PCBs Under Right-Side of the Table ........................................................ 5-5
5.3.3 Table Y Belt .............................................................................................. 5-6
5.3.4 Table Y Motor or Gearcase ...................................................................... 5-7
5.3.5 Table Y Encoder ....................................................................................... 5-7
5.4 Table X FRUS ................................................................................................... 5-8
5.4.1 Table X Motor Controller PCB ................................................................ 5-9
5.4.2 Table X Belt ............................................................................................ 5-10
5.4.3 Table X Motor or Gearcase .................................................................... 5-10
5.4.4 Table X Encoder ..................................................................................... 5-11
5.5 Table Z FRUs (A and SL only) ...................................................................... 5-12
5.5.1 Pedestal ................................................................................................... 5-12
5.5.2 The Linear Rotary String (Encoder) ....................................................... 5-14
5.6 Lower C-Arm FRUS ........................................................................................ 5-16
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Discovery QDR Series Technical Manual
5.6.1 C-Arm Interface Board ........................................................................... 5-17
5.6.2 X-Ray Controller Assembly ................................................................... 5-18
5.6.3 Filter Drum Assembly ............................................................................ 5-18
5.6.4 Tank Assembly ....................................................................................... 5-19
5.6.5 Arm R FRUS (A and SL only) ............................................................... 5-21
5.6.6 Motor Controller Board ......................................................................... 5-23
5.6.7 Arm R Belt .............................................................................................. 5-23
5.6.8 Arm R Motor, Gearcase, Encoder or Encoder Belt ................................ 5-24
5.6.9 Gas Spring ............................................................................................... 5-25
5.7 Upper C-Arm FRUS ........................................................................................ 5-25
5.7.1 Detector Assembly A, SL, W, C Systems .............................................. 5-26
5.7.2 Detector Assembly C1 and Wi Systems ................................................. 5-27
5.7.3 Laser Assembly ....................................................................................... 5-29
5.7.4 Analog to Digital Converter Board (A Model only) ............................... 5-30
5.8 Aperture Assembly FRUS ............................................................................... 5-31
5.8.1 Aperture Stepper Motor .......................................................................... 5-31
5.8.2 Aperture Motor PCB ............................................................................... 5-32
5.8.3 Aperture Position Belt ............................................................................ 5-32
5.8.4 Rotary Potentiometer .............................................................................. 5-33
5.9 Drum Assembly FRUS .................................................................................... 5-34
5.9.1 Drum Encoder PCB ................................................................................ 5-34
5.9.2 Drum Belts .............................................................................................. 5-36
5.9.3 Stepper Motor Assembly ........................................................................ 5-37
5.9.4 Drum Bearings ........................................................................................ 5-37
5.10 Replacing EMI Cables ................................................................................... 5-40
5.11 FRU Lists ....................................................................................................... 5-41
Chapter 6 -
FAULT ISOLATION
6.1 Before Starting ................................................................................................... 6-1
6.2 Software Configuration ...................................................................................... 6-1
6.3 Hardware Configuration .................................................................................... 6-1
6.4 Power Problems ................................................................................................. 6-1
6.5 Motion Problems ................................................................................................ 6-2
6.6 Control Panel Problems ..................................................................................... 6-5
6.7 Display Problems ............................................................................................... 6-5
6.7.1 Vertical Stripe ........................................................................................... 6-5
6.7.2 Horizontal Stripe ....................................................................................... 6-6
6.7.3 Noise ......................................................................................................... 6-7
6.7.4 No Display ................................................................................................ 6-7
6.8 Targeting/Laser Problems .................................................................................. 6-8
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Discovery QDR Series Technical Manual
6.9 Data Communications Problems ....................................................................... 6-8
6.10 Area/BMD/BMC/CV Specification Problems ................................................. 6-9
6.11 X-Ray Problems ............................................................................................... 6-9
6.11.1 No X-Rays .............................................................................................. 6-9
6.12 X-Ray Alignment Problems ............................................................................. 6-9
6.12.1 X-Ray beam does not align properly ...................................................... 6-9
6.12.2 System Fails X-Ray Beam Alignment Verification ............................. 6-10
6.13 Detector Flattening Problems ........................................................................ 6-10
6.13.1 System Consistently Fails the Detector Flattening Procedure .............. 6-10
6.14 Laser Problems .............................................................................................. 6-11
6.15 Oil leakage ..................................................................................................... 6-12
6.15.1 The Torque Specifications .................................................................... 6-12
6.15.2 Tank Top Cover Components and Screw Location .............................. 6-12
6.15.3 Tightening the Lexan Cup Screws ........................................................ 6-13
6.15.4 Tightening the Bladder Gasket Screws ................................................. 6-13
6.15.5 Tightening the Transformer Seal Screws .............................................. 6-14
6.15.6 Tightening the Tank Cover Gasket Screws .......................................... 6-14
6.16 Miscellaneous Problems ................................................................................ 6-15
Chapter 7 -
PREVENTIVE MAINTENANCE
7.1 Customer Preventive Maintenance .................................................................... 7-1
7.2 Field Service Preventive Maintenance .............................................................. 7-1
7.2.1 Guide Rail and Bearing Maintenance ....................................................... 7-3
Chapter 8 -
PCB SUMMARY INFORMATION
Chapter 9 -
SOFTWARE TOOLS
9.1 X-Ray Survey .................................................................................................... 9-1
9.1.1 Invoking X-Ray Survey ............................................................................ 9-1
9.1.2 The Main Display ..................................................................................... 9-2
9.1.3 The Display Controls ................................................................................ 9-3
9.2 SQDRIVER ....................................................................................................... 9-9
9.3 SQVERIFY ...................................................................................................... 9-10
9.4 SQKEYPAD .................................................................................................... 9-10
Appendix A -
ERROR MESSAGES
viii Table of Contents
Section 1
INTRODUCTION
1.1 System Overview
The Hologic Discovery® X-ray Bone Densitometer (Discovery-C and -W is shown in Figure 1-1
on Page 1-2; Discovery-A and -SL is shown in Figure 1-2 on Page 1-2) estimates the bone
mineral content (BMC) and bone mineral density (BMD) of selected areas of the body or of the
entire skeleton. It does so using X-rays of two different energy levels. This dual-energy scheme
allows soft tissue within the selected area to be subtracted out leaving only bone to be scanned
and estimated.
This manual uses "Discovery" to refer to all models in the Discovery series of systems.
Information presented in this manual that applies only to a particular model, or models, will be
noted as such.
The patient lies face up on the table and, with the aid of a cross-hair laser, the operator positions
the scanning arm over the region of interest. After entering patient data and selecting the type and
size of scan desired, the operator initiates the scan with a single keystroke.
The operator is not required to select technique factors as tube current and voltage are preselected and fixed. Since testing is performed by fan beam method, rather than by flooding the
area as in conventional radiography, the scanning time is a function of the dimensions of the area
to be measured, the desired resolution, and the desired precision.
BMC results are expressed in grams of calcium hydroxyapatite and BMD is reported in grams/
cm2 of the same compound.
In most cases, no additional shielding is necessary for patient, operator, or room. The Discovery
system can be placed in any convenient non-shielded examination room. Contact your state
regulatory agency for details about additional shielding requirements, if any.
The Discovery system employs a patented Automatic Internal Reference System, which
continuously calibrates the machine to eliminate the effects of variations in temperature, tube
flux, etc. No daily calibration is required. The daily scanning of a quality control phantom is
required to provide assurance that the system is functioning correctly and to aid in the detection of
any long-term drift.
The X-ray scans produced by the Discovery, and displayed on the monitor, are intended only to
locate anatomical sites for measurement and to assure the operator that the machine is operating
properly. They are not intended as a substitute for conventional film-based diagnostic scans.
1-1
Discovery QDR Series Technical Manual
Figure 1-1. Discovery®-C and -W System
Figure 1-2. Discovery®-A and -SL System
1.1.1 X-Ray Scanning Principles
An X-ray source, consisting of a high voltage generator and X-ray tube in a common,
shielded enclosure, is mounted beneath the patient on the C-Arm. It generates a narrow,
tightly collimated, fan-shaped beam of X-rays which alternate, at power line frequency,
between 100kVp and 140kVp. At the other end of the C-Arm, above the patient, is a
crystal/solid state detector array. During a scan, the C-arm and table move, under
computer control, to guide the beam over the desired scan area.
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Discovery QDR Series Technical Manual
Before passing through the patient, the beam is filtered through a rotating drum in which
alternating segments having radio-opacities equivalent to tissue, bone and air are located.
When finally intercepted by the detector, the beam contains information about the X-ray
absorbing characteristics of both the patient and the calibration materials in the filter
drum. An A/D converter, fed by the detectors, supplies a complex digital signal to the
computer, which uses that signal both to construct the screen display, and as the basis for
its computations of BMC and BMD.
The Discovery computer algorithm is based on the principle that bone attenuates the X-ray
beam differently at high and low energies. The bone mineral content of any sample point
can be computed from:
Q= L - kH
where L and H are the logarithms of the sample attenuation at high (140kVp) and low
(100kVp) energies, respectively. The constant k depends on the tissue attenuation
characteristics of the beam. In the Discovery, k is continuously measured using the
“tissue” segment in the filter wheel.
The program works in the following manner:
1. Load preliminary scan and obtain regions of interest from operator.
2. Estimate k as an average value of:
k = [L
where L
tissue
interposed by the filter drum, and L
Note: The subscript "
- L
tissue
] / [H
air
tissue
- H
air
]
indicates a low-energy me as ureme nt with tissue -equi vale nt m aterial
, H
air
" designates the filter drum segment that is empty (i.e., contains
air
tissue
and H
are similarly defined.
air
neither bone- nor tissue-equivalent material).
3. Using this value of k, calculate Q for each point scanned using the formula given
above (Q = L - kH). This array of Q values constitutes a "Q scan". Displays the Q
scan.
4. Compile a histogram of the Q values. Because a large portion of the scan con-
tains soft tissue only, this histogram will have a large peak. Choose a threshold
value just above this peak, and apply that value to discriminate, point by point in
the Q scan, between "bone" points (whose Q is above the threshold) and "nonbone" points (whose Q is below the threshold).
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Discovery QDR Series Technical Manual
Figure 1-3. Q Scan Plot
5. Use the "non-bone" points to calculate a baseline value for each scan line. Using
these points, form a new histogram and repeat steps 4 and 5 until the results con
verge.
6. Smooth the segment boundaries to eliminate isolated noise-generated "bone"
points.
-
7. Display the "bone" and "non-bone" points for operator approval.
8. Determine the constant of proportionality (d0) that relates the Q values to actual
BMC (grams). This constant is determined by measuring how much Q shifts
when bone-equivalent material is interposed by the filter drum.
9. Calculate the total bone mineral values by adding up the Q values for all "bone"
points in each region of interest (e.g., each vertebra), and multiplying by d0.
10. Determine the bone areas by counting the number of "bone" points in each region
of interest.
11. Calculate bone mineral density as:
BMD = BMC / area
12. Display the calculated results and print the report.
1.2 Functional Overview
This section provides block diagrams of the Discovery system along with a brief
functional overview of each diagram and block. A detailed functional description along
with interconnection diagrams and interconnection descriptions is provided in Section 2 of
this manual.
1-4
Discovery QDR Series Technical Manual
Figure 1-4. Discovery System Block Diagram
The Hologic Discovery consists of essentially three conceptual subsystems. These
subsystems are the Operator’s Console, Motor Control Subsystem, and C-Arm
Subsystem.
The Operator’s Console is the input/output subsystem of the instrument and consists of a
PC running the Discovery system software under Windows XP® and the PCI
Communications Controller Board manufactured by Hologic. The software communicates
with the scanner sending out arm and table motion commands, X-Ray commands, and Xray detection commands. The software also checks to see that commands have been
completed and issues an appropriate error message when a command fails.
The Motor Control subsystem of the scanner is controlled by the Distribution Board. All
motor movement commands are routed through the Distribution Board to the individual
Motor Drivers. There is one Motor Driver for each motor: Arm Y direction (A Y), Table X
direction (TX), T able Y directio n (TY) (A and W models only), and Arm Rotation (AR)(A
and SL models only). The Distribution Board also distributes the DC power throughout
the scanner. Circuit breakers for each Motor Driver can be found on the Distribution
Board.
The C-Arm subsystem controls the generation and detection of X-rays. It processes the
commands received from the Distribution Board and passes them to the X-Ray Controller
or the Detector Assembly. The X-Ray Controller, as its name implies, controls the
generation of the X-Rays by the X-Ray Source or “Tank”. The X-Rays pass through the
patient and are sensed by the Detector Assembly.
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Discovery QDR Series Technical Manual
Power
Strip
Keyboard
Mouse
Modem
Network I/F Card
Printer
Monitor
Phone
Jack
AC
AC
AC
Network
Jack
Discovery
Scanner
Video
Computer
AC from
DIN Rail
(Scanner)
AC
PCI
Communications
Controller
Figure 1-5. Discovery Operator's Console Block Diagram
The Discovery Operator’s Console consists of a Pentium PC on a convenient, roll-around
computer cart designed specifically for the Discovery PC. AC power from the scanner is
fed to the Operator’s Console via a power strip attached to the PC cart.
The Pentium PC contains the video controller board to drive the monitor and the PCI
Communications Controller Board to interface the PC to the Scanner. A modem card is
provided for remote communications with other PCs. A Network Interface Card (NIC) is
installed to control communications with the Hologic QDRNet® or a DICOM® network.
The mouse gives the operator easy control over the Windows XP-based Discovery
software and the keyboard is used for data input to the Discovery software. A color inkjet
printer is provided with the PC. An optional laser printer can be substituted for the inkjet
printer.
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Discovery QDR Series Technical Manual
TY Stepper
Motor Driver
TX Stepper
Motor Driver
AY Stepper
Motor Driver
TY
Motor
TY
Encdr
TX
Motor
TX
Encdr
AY
Motor
AY
Encdr
Signal
Distribution
Board
To/From C-Arm Interface
To/From Control Panel Interface
To/From
Communications
Controller
+/-15V
JP1
+24V
From DIN
Rail
and LVPS
AR Stepper
Motor Driver
AR
Motor
AR
Encdr
TZ Stepper
Motor Driver
TZ
Motors
TZ
Encdrs
AC
JP4
JP5
JP7
JP11
JP8
JP6
JP10
Figure 1-6.Discovery Distribution and Motor Control Block Diagram
The heart of the Discovery Scanner is the Distribution Board. This board interfaces the PC
to the different subsections of the Scanner, distributes control signals to the table and CArm, and distributes DC power throughout the Scanner. The Distribution Board receives
command inputs from the PCI Communications Controller Board in the PC and voltages
from the DIN rail and Low Voltage Power Supply. Commands and voltages dealing with
the generation of X-Rays or the acquisition of scan data are transferred to the C-Arm
Interface Board, which controls both functions. The Distribution Board also receives
Table and C-Arm motion commands from the PCI Communications Controller Board in
the PC.
When a motion command is received, the Distribution Board routes the command along
with a board address to the Motor Driver Boards. The addressed Motor Driver Board
converts these digital commands into analog signals that are strong enough to drive the
motors. A Position Encoder attached to the idler pulley moved by the motor, senses
changes in the position of the arm or table. This device provides a voltage feedback to the
Motor Driver Board that is translated into a motor position, which in turn, is fed back to
software in the Operator’s Console PC.
The Discovery Control Panel is located at the head end of the table and communicates
with the Distribution Board via the Control Panel Interface Board. The Control Panel
provides the operator with a means to issue manual commands to move table and arm
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Discovery QDR Series Technical Manual
C-Arm
Interface
Board
Detector Board
(Detectors, Muxes,
and A/D Converter)
Aperture Motor
and
Position Sensor
Filter Drum Motor
and
Position Sensor
Laser
Assembly
Detector Assembly
X-Ray
Controller
X-Ray
Source
(Tank)
To/From
Distribution
Board
From
DIN
Rail
motors, turn power to the instrument on or off, and an indicator showing when X-rays are
being generated.
The C-Arm Interface Board controls the C-Arm Subsystem. Commands to the subsystem
arrive from the Distribution Board. The commands processed by the C-Arm Interface
Board are sent to the Positioning Laser, the X-Ray Control ler (XRC ), the Ape rture M otor,
the Detector assembly, or the Filter Drum Assembly. The commands sent to the
Positioning Laser are simple on/of f commands. Commands sent to the XRC tell it when to
produce X-rays, which power level of pulse to produce, and the pulse mode to be used.
These commands will subsequently control the way the X-Ray Source (Tank) is driven by
the XRC. Instructions to the Aperture Motor are for selecting the aperture to be used for
the scan. The commands to the Filter Drum Assembly turn the Filter Drum on or off and
synchronize the filter drum with the AC line waveform. The last set of command signals is
sent to the Detector Assembly to synchronize the acquisition of data with the production
of the X-rays from the source (Tank).
The C-Arm Interface Board collects data from most of the circuits mentioned above for
transmission back to the Distribution Board and, finally, the Discovery software. The
Figure 1-7. Discovery C-Arm Block Diagram
Aperture Motor Assembly sends back position information indicating which of the
aperture slits is in position. The Filter Drum Assembly sends back filter and reference
phase information. The XRC sends back information concerning fault conditions, beam
conditions, and an AC Line signal for generating AC Line Interrupts to the software. The
Detector Board sends data collected from scans back to the software through the C-Arm
1-8
Discovery QDR Series Technical Manual
Interface Board and the Distribution Board. Mathematical algorithms applied to this data
produce the scans seen by the operator and to calculate the BMD, BMC, and area of the
bone matter scanned.
Block Description
Computer Controls and commands all Discovery hardware modules.
PCI Communications
Controller Board
Distributi on Board Provides the interconnections between the Discovery Operator's Console and the
Control Panel Provides switches for manually moving the C-Arm and Patient Table. Also
TX Stepper Motor
Driver
TY Stepper Motor
Driver
TZ Stepper Motor
Driver
AR Stepper M otor
Driver
AY Stepper Motor
Driver
C-Arm Interface Controls the Aperture and Filter Drum motors, generates timing and control signals
X-Ray Controller Controls the operation of the X-ray Source.
Controls the flow of commands to and from the Scanner modules via the
communications bus.
Scanner and distributes DC voltages.
provides Emergency Stop and Instrument On/Off switches.
Controls the motion of the Patient Table in and out motor and monitors table
position information from the encoder.
Controls the motion of the Patient Table left to right motor and monitors table
position information from the encoder (A and W only).
Controls the motion of the Patient Table left and right pedestal motor and monitors
table position information from the string encoders (A and SL only).
Controls the rotational motion of the C-Arm and m onitors C-arm position
information from the encoder (A and SL only).
Controls the motion of the C-Arm left and right motor and monitors C-Arm
position information from the encoder.
for the X-Ray Controller and the Data Acquisition System, monitors the tape
switches, and provides power to the Positioning Laser.
X-Ray Source Unit Generates the X-ray beam.
Detector Board Converts the X-rays into electrical signals. Integrates the signals from the Solid
State Detectors and converts them to a digital value in the Analog-to-Di git a l
converter circuitry.
Control Panel Provides the operator with a means to reposition the table, C-Arm, and to turn on
the laser.
Positioning Laser Provides a laser crosshair beam to assist in positioning the patient on the Patient
Table.
1-9
Discovery QDR Series Technical Manual
1.3 Product Specifications
SPECIFICATION MODEL DEFINITION
Scanning Me t hod All Multi-detector array, indexing table, and motorized C-arm
X-ray System All Switched Pulse Dual-Energy X-ray tube, operating at 100 and
140kV, 5mA avg. at 50% duty cycle, 2.5mA avg. at 25% duty
cycle (30sec. maximum), Tungsten target
Detector System A 216 multi-channel detector consisting of CdWO4 scintillators
coupled to silicon diodes
SL/C/ W 128 multi-channel detector consisting of CdWO4 scintillators
coupled to silicon diodes
Scanning Sites A Lumbar spine (in AP and lateral projections), proximal femur
(hip) forearm, IVA Spine, and whole body
SL Lumbar spine (in AP and lateral projections), proximal femur
(hip), IVA Spine, and forearm
W Lumbar spine (in AP and decubitus lateral projections),
proximal femur (hip), forearm, IVA spine (AP only) and whole
body
C Lumbar spine (in AP and decubitus lateral projections),
proximal femur (hip), forearm, and IVA spine (AP only)
Scan Region A 1.95m (76.77 in.) x.65m (25.59 in.) maximum
SL 96cm (38 in.) x .65m (25.59 in.) maximum
W 1.97m (77.5 in.) x.65m (25.59 in.) maximum
C .96m (38 in.) x.51m (20 in.) maximum
Scatter Radiation All Less than 10µGy/h (1mrad/h) at 2m (79 in.) from the center of
the X-ray beam for all scans
Leakage Radiation All The Discovery meets the requirements of 21 CFR 1020.30(k)
for leakage from the X-ray source
External Shielding
Requirement
Calibration All Self Calibrating using Hologic Automatic Internal Reference
All Contact state regulatory agency.
System. Operator calibration NOT required.
1-10
Discovery QDR Series Technical Manual
SPECIFICATION MODEL DEFINITION
System Weight
installed
A & SL 327kg 720lb 34.1kg 75lb
C & W 295kg 650lb
System Weight
shipping
Operating
Temperature
Humidity All 20 – 80% relative Humidity, non-condensing
Storage
Temperature
Humidity All 20 – 80% relative Humidity, non-condensing
Footprint Length Width
T ab le extended A & W 3.02 119 1.50
T ab le not exte nded A & W 2.02 79.5 1.22
Average Heat Load ALL 1000w (3400 BTU/hr)
A & SL 659kg 1450lb
C & W 568kg 1250lb
All
All
C & SL 2.02 79.5 1.40
Scanner Console
System
15o – 32o C (59o - 90o F)
15o – 32o C (59o - 90o F)
m inches m
inches m inches
59 1.42 56
48 1.42 56
55 1.42 56
Height
Patient Table
Height
Positioning Laser All Diode laser (<1mW) cross hair, with emergency mechanical shutter
X-Ray Collimation All Dual movable aperture with 0.5mm and 1.0mm slits
Leakage Current All Normal <75µA Single Fault <400µA
Resolution All 0.5 line pair/mm approximately 1.0mm
A & SL Adjustable, 71cm (28 in.) from floor when scanning in AP mode
86.4cm (34 in.) at maximum elevation
C & W 71cm (28 in.) +/- 25mm (1 in.)
1-11
Discovery QDR Series Technical Manual
1.3.1 Exam Mode(s) Performance
Exam Type Model Default
Scan
Length (in.)
AP Spine High
Def
AP Spine Array All 8.0 82 L1, L2, L3, L4 0.20 1.0
AP Spine Fast All 8.0 41 L1, L2, L3, L4 0.10 1.0
AP Spine Turbo All 8.0 21 L1, L2, L3, L4 0.05 1.0
Express Scan All 8.0 10 L1, L2, L3, L4 0.07 1.0
Decubitus Lateral
Spine Fast
Lat Spine High
Def
Lat Spine Array A & SL 8.0 240 L1, L2, L3, L4 0.70 1.0
Lat Spine Fast A & SL 6.0 120 L1, L2, L3, L4 0.35 1.0
Hip High Def All 6.0 123 Femur (Total) 0.20 1.0
Hip Array All 6.0 62 Femur (Total) 0.20 1.0
Hip Fast All 6.0 31 Femur (Total) 0.10 1.0
All 8.0 163 L1, L2, L3, L4 0.20 1.0
C & W 8.0 160 L2, L3, L4 0.40 1.0
A & SL 8.0 240 L1, L2, L3, L4 0.35 1.0
D u r a tion(s)
@ Default
Length
Scan Site Dose
mGy
max
in vivo
Precision
(%)
Hip Turbo All 6.0 16 Femur (Total) 0.05 1.0
Dual Hip All 6.0 2X Scan Mode Left & Right
Femur
Whole Body W 77.0 402 Whole Body 0.015 1.0
A 77.0 180 Whole Body 0.01 1.0
Forearm All 6.0 31 Forearm
(Radius &
Ulna) (Total)
IVA SE AP
Imaging
IVA SE R/L
Lateral
IVA DE R/L
Imaging
Small Animal
Spine and Femur
Small Animal
Whole Body
All 16.1 10 Spine T5-L4 0.07 NA
All 16.1 10 Spine T5-L4 0.07 NA
All 13.6 511 Spine T5-L4 0.35 NA
A 2/3 149 Spine & Femur NA NA
A 12.0 122 Whole Body NA NA
Selecte
d Scan
Mode
0.10 1.0
Selected
Scan
Mode
1-12
Discovery QDR Series Technical Manual
1.3.2 Duty Cycle:
C, W and SL IVA 12%
All Others 50%
A Whole Body 100%
IVA 12%
All Others 50%
1.3.3 Leakage Technique Factors
The leakage technique factors for all models of Discovery are the same. It is the maximum
continuous current at the maximum peak potential. This is X-ray mode #3. Peak potential
100/140kVp (dual energy), current 10mA peak 25% duty cycle or 2.5mA average.
1.3.4 Minimum Beam Filtration
The minimum filtration permanently in the beam is 3.7mm Al equivalent @80kV.
1.3.5 Measured Half Value Layer (HVL) At Different Operating Potentials
Measured operating potential Measured Half Value Layer
Discovery All
80kV 3.7mm Al equivalent
100kV 5.0mm Al equivalent
140kV 6.5mm Al equivalent
1.3.6 Line Voltage and Maximum Line Current
Power
Requirements:
All 100VAC 16A 50/60Hz, Max apparent resistance = 0.32 ohm
120VAC 14A 50/60Hz, Max apparent resistance = 0.32 ohm
230VAC 8A 50/60Hz, Max apparent resistance = 1.28 ohm
1.3.7 Technique Factors for Maximum Line Current
Peak Potential 140kVp
Tube Current 10mA peak, 50% duty factor or 5mA average.
1-13
Discovery QDR Series Technical Manual
1.3.8 Maximum Deviation
The maximum deviation from the preindication given by labeled technique factor control
settings or indicators are as follows:
Peak Potential: +/- 15%
Current: +/- 40%
Time: +/- 10%
1.3.9 Measurement Criteria for Technique Factors
The measurement criteria of the technique factors is as follows:
Peak Potential: The voltage peak is measured with an oscilloscope. Voltage is a squarewave pulse.
Peak is defined as the peak voltage of the 4 millisecond pulse, discounting any initial
overshoot.
Current: Current is measu red with an oscilloscope on the last millisecond of the 4 millisecond
pulse.
Time: Time of each pulse is measured with an oscilloscope and defined as the time between
50% rise and fall times of the peak potential pulse. Time of the scan is measured by
counting the number of AC line pulses from the start to the end. X-ray pulses are
synchronous with the AC line.
1-14
Section 2
FUNCTIONAL DESCRIPTION
This section provides a detailed functional description along with interconnection diagrams and
descriptions of the Hologic Discovery. Refer to Section 1 for a block diagram and a brief
functional description of each block.
2.1 Computer
The Discovery Scanner is interfaced to a PCI Communications Controller Board/ISA Bus
computer which controls table and C-arm movement, X-ray generation, performs all necessary
calculations, and manages both the patient and QC database information.
The computer is a Pentium III-based (or higher) PC that comes equipped with floppy disk drive,
hard disk drive, keyboard, mouse, 17” color monitor, and CDROM R/W for archiving scans and
backups of the system database. For details pertaining to the computer and its associated
components, please refer to the documentation shipped with each unit.
2.2 PCI Communications Controller Board
The PCI Communications Controller Board handles all the communications between the
Computer and the Scanner C-Arm and Table assemblies. The board resides in one of the computer
internal ISA slots and communicates with the computer via the computer's I/O bus. It connects to
the Distribution Board in the Scanner through a 50-conductor ribbon cable. This cable contains
two independent communications links (one synchronous and one asynchronous) and additional
system control signals. Each signal requires a pair of conductors for differential (RS422) noise
immunity.
The asynchronous link communicates with the Motor Controller Boards (TX, TY, AR, and AY),
the TZ Drive Board, the C-Arm Interface Board, and the Control Panel Controller section of the
Detector Board (or the Control Panel Interface on A and SL models). The synchronous link
communicates with the Data Acquisition System (DAS).
2.2.1 Interface Connections
Figure 2-1 on page 2-3 describes the interconnections between the PCI Communications
Controller Board and the Distribution Board. The table also identifies the connectors and their pin
assignments.
2-1
Discovery QDR Series Technical Manual
Table 2-1. PCI Communications Controller Board/Distribution Board
Interconnection Descri ptio ns
.
Signal Pair Description
ATD+
ATD-
STD+
STD-
STCLK+
STCLK-
STFRM+
STFRM-
ARD+
ARD-
SRD+
SRD-
SRCLK+
SRCLK-
SRFRM+
SRFRM-
EMERGENCY_IN+
EMERGENCY_IN-
Asynchronous data to the Scanner. JP1-2
Synchronous data to the Scanner. JP1-28
Synchronous data clock from PCI Communications
Controller Board to Distribution Board. Synchronizes
data to the Scanner.
Synchronous data frame from PCI Communication
Command Board to Distribution Board.
Asynchronous Data from the Scanner. JP1-8
Synchronous Data from the Scanner. JP1-34
Synchronous data clock from PCI Communication
Command Board to Distribution Board. Synchronizes
data from the Scanner.
Synchronous data frame from Distribution Board to
PCI Communication Command Board.
Signals an emergency condition. Generated by the CArm Interface Board.
PCI1 Pin Dist2 Pin
JP10-3
JP1-27
JP1-4
JP1-5
JP1-30
JP1-31
JP1-7
JJP1-33
JP1-10
JP1-11
JP1-36
JP1-37
JP1-13
JP1-14
JP1-39
JP10-4
JP10-6
JP10-7
JP10-9
JP10-10
JP10-12
JP10-13
JP10-15
JP10-16
JP10-18
JP10-19
JP10-21
JP10-22
JP10-24
JP10-25
JP10-27
JP10-28
ZEROX+
ZEROX-
INTEGRATE+
INTERGATE-
SYSRESET+
SYSRESET-
EMERGENCY+
EMERGENCY-
AC line zero-crossing signal used for system wide
synchronization. Generated by the C-Arm Interface
Board.
Synchronous signal for Detector Integrate period.
Generated by the C-Arm Interface Board.
Resets the Scanner controllers. JP1-20
Removes power from the Scanner motor drivers and
the X-ray system
Note: 1 PCI = PCI Communication Controller Board
2 Dist = Distribution Board
JP1-40
JP1-16
JP1-17
JP1-42
JP1-45
JP1-49
JP1-25
JP10-30
JP10-31
JP10-33
JP10-34
JP10-39
JP10-40
JP10-48
JP10-49
2-2
Discovery QDR Series Technical Manual
KP1085_004-0201
PCI
Communication
Command
Board
DISTRIBUTION
BOARD
Figure 2-1. PCI Communication Command Board/Distribution Board
Interconnection Diagram
2.3 Distribution Board
The Distribution Board provides interconnections between the Discovery Operator's
Console (PC) and the Scanner. It passes several signal lines from the Operator's Console
and power lines from the DIN rail directly to the C-Arm Interface module. It also provides
buffering and individual drivers and receivers for various signal lines to and from
individual Scanner modules and the PCI Communication Command Board. The
Distribution Board is located in the Electronics Tray in the base of the Scanner.
One cable connects the Operator's Console (PC) communications bus to the Distribution
Board. One cable connects to the Distribution Board from the DIN rail. This cable brings
DC power to the Distribution Board and connects the X-Ray On and Emergency signal
lines to the Power Module.
Up to eight cables connect the Distribution Board to the various Scanner boards
depending on instrument model. Four cables connect to the four Motor Controller Boards
(Table X, Table Y, Arm R, and Arm Y). A single cable connects to the TZ Drive Board.
T wo cables (one signal and one power) connect to the C-Arm Interface Board. In addition,
one cable connects to the scanner Control Panel Interface Board. In the C and W models,
this board is a separate section of the Detector Board. In the A and SL versions, the
Control Panel Interface Board is a separate board located under the table.
The Distribution Board has provision for three jumpers that can be installed to override
the EMERGENCY signal lines when troubleshooting.
2.3.1 Power
The Distribution Board receives +24 and +/-15VDC from the Multi-voltage DC Switching
Power Module. The +24VDC is applied through four individual circuit breakers to the
Table X, Table Y, Arm R, and Arm Y Motor Controller Boards. The +24 and +/-15VDC
are passed to the C-Arm Interface Board. The +24 VDC is also reduced to +7 and +5VDC
by regulators to power op-amps and analog switches located on this board. The +7VDC is
passed to the Control Panel Controller Board. The +5VDC powers the digital section of
2-3
Discovery QDR Series Technical Manual
COMMUNICATIONS
CONTROLLER
BOARD
OPERATOR’S
CONSOLE
COMPUTER
INSTRUMENT
ELECTRONICS
TRAY
the Distribution Board. The +24VDC power supply is not closely regulated and its outputs
may range from +24V to +35V under normal conditions.
Note: +7VDC may measure anywhere from +6.25VDC to +7.25VDC. This is true
everywhere +7VDC is shown in this manual.
Limits for +/- 15VDC
Six green LEDs indicate the status of the +28 (on QDR-4500s, +24 on Discovery), +24,
+15, -15, +7 and +5VDC (ON indicates the respective voltage is present). Five red LEDs
indicate the status of the five circuit breakers applying voltage to the motor drivers/
controller. ON indicates the circuit breaker has been tripped by an over-current condition.
2.3.2 Interface Connections
Figure 2-2 shows connections to/from the Distribution Board.
Figure 2-2. Distribution Board High Level Interconnection Diagram
2-4
Discovery QDR Series Technical Manual
2.4 Motor Controller Boar d
The Motor Controller Board is a microprocessor controlled power driver circuit for use
with a two-coil bipolar stepper motor. It receives high-level commands through the
Distribution Board from the host computer, and applies 24-volt pulses to the stepper motor
windings. The Discovery uses four identical Motor Controller Boards to control and drive
the Table X (Table In/Out), Table Y (Table Left/Right), C-Arm Y (C-Arm Left/Right), CArm R (Arm rotation, A/SL only) stepper motors. The motor windings are driven by two
integrated H-bridges. These integrated circuits provide internal level conversion and
power limiting. Their logic level control inputs are driven from a stepper motor control
microcircuit that receives commands from the microprocessor. The control circuit senses
the current in the motor windings and adjusts the duty cycle of the applied voltage in such
a way as to limit the maximum motor current. The maximum value is determined by an 8bit control word at a Digital to Analog Converter.
Each Motor Controller Board monitors the position of its respective mechanism using a
voltage received from an associated Position Encoder connected to the mechanism. The
Position Encoder is a precision potentiometer that divides a +/-3V reference source. The
output voltage is fed to a sense amplifier in proportion to the position of the mechanism
driven by the motor. The sense amplifier output is converted to digital value that provides
position feedback to the microprocessor.
The Motor Controller Boards receive movement commands from the Discovery computer
via the communications bus. Each Motor Controller Board contains an ID switch and four
status indicators (LEDs). The ID switch is a 16-position rotary encoded switch (SW1) that
is read during system initialization to determine the Motor Controller Board address for
communicating with the Discovery computer. ID switch settings for the Motor Controller
Boards are as follows:
Table X drive 4
Table Y drive 5
C-Arm Rotation 6
C-Arm Y drive 7
The four red status LEDs provide visual indications of motor drive power on, Stepper
CPU active, motor drive direction, and motor step pulses.
The Motor Controller Board also has provision (JP2) for connecting limit switches to
inhibit motor operation when the mechanism goes beyond established mechanical limits.
This feature is not used in the Discovery and, therefore, no cable is connected to JP2.
2.4.1 Power
Power input to the Motor Controller Board is +24VDC. This voltage provides the motor
drive power and is converted down to +5VDC for use by logic circuits on the board. The
+5VDC is also converted to -5VDC. Two green LEDs provide a visual indication of the
power present on the Motor Controller Board.
2-5
Discovery QDR Series Technical Manual
ARD+, ARDATD+, ATDSYSRESET+, SYSRESET+28V
28V_RET
(⎯)
(⎯)
(⎯)
(⎯)
+REF
(⎯)
-REF
MOTOR
CONTROLLER
STEPPER
MOTOR
To/From
Distribution Board
POSITION
ENCODER
2.4.2 Interface Connections
Figure 2-3 shows the typical interconnections between the Distribution Board, the Motor
Controller Board, the Stepper Motor, and the Position Encoder. Figure 2-1 describes the
interconnections between the Distribution Board and the Motor Controller. Table 2-3
describes the interconnections between each Motor Controller and its respective stepper
motor and position encoder. The tables also identify the connectors and their pin
assignments.
Figure 2-3. Distribution Board/Motor Controller Board Interconnection Diagram
Table 2-2.Distribution Board/Motor Controller Board Interconnection Descriptions
Signal Description Table X Table Y C-Arm Y Pin(s)
ARD+
ARD-
ATD+
ATD-
SYSRST+
SYSRST-
28V
28V_RET
Asynchronous Receive Data. JP7 JP5 JP11 11
12
Asynchronous Transmit Data. JP7 JP5 JP11 14
15
System Reset. Resets the Motor
Controller Board.
DC power for the Motor
Controller Board.
JP7 JP5 JP11 17
18
JP7 JP5 JP11 2,3,4,5
1,6,7,8
Table 2-3. Motor Controller Board/Stepper Motor and Position Encoder
Interconnection Descriptions
Signal Description Pin
(No label) Motor drive signals (4). JP5-1 - JP5-4
+REF (+3V) Precision posit ive v oltage to position potentiometer. JP3-1
(No label) Position encoder wiper return voltage. JP3-3
-REF (-3V) Precision negative voltage to position poten tiome ter. JP3-5
2.5 TZ Drive Board (A and SL Only)
The TZ Drive Board is a microprocessor-controlled power driver circuit for the two AC
pedestal motors, which raise and lower the patient table of the Discovery A and SL. This
2-6
Discovery QDR Series Technical Manual
board is located in the Electronics Tray in the rear of the bottom of the Scanner base
assembly.
The TZ Drive Board communicates with the PCI Board, via the Distribution Board, to
drive the pedestal motors under computer control. Manual repositioning of the pedestal
may be required in case of an emergency . In this case, manual control is provided through
the Table switches of the Scanner’s Operator Control Panel.
The TZ Drive board monitors the position of both pedestals using signals received from an
associated Position Encoder connected to the respective pedestal.
2.5.1 Service Switches
The TZ Drive board contains four service switches used during replacement of a defective
pedestal or Position Encoder. Table 2-4 describes these switches and their respective
functions.
Caution: The TZ drive motors are designed to run at a 5% duty cycle. If the motors
overheat, the built-in thermal cutouts may trip and cause the motors to stop
functioning. If this occurs, you must wait about 20 minutes before
functionality is restored.
The TZ drive motors are designed to run at a 5% duty cycle. If the motors overheat, the
built-in thermal cutouts may trip and cause the motors to stop functioning. If this occurs,
you must wait about 20 minutes before functionality is restored.
Table 2-4.TZ Drive Service Switches
Switch Function
Mode (Normal/Service) Determines whether the TZ Drive is in Normal or Service
operation.
Direction (Up/Down) When the TZ drive is in Service mode, determines the
direction of pedestal movement (not active in normal
mode).
Left When the TZ drive is in Service mode, moves the left
pedestal in the direction specified by the Direction switch
(not active in normal mode).
Right When the TZ drive is in Service mode, moves the right
pedestal in the direction specified by the Direction switch
(not active in normal mode).
Reset Resets the board after manual operation. The TZ Drive
board must be reset after any manual operation.
2.5.2 Power
Power input to the TZ Drive Board is +24VDC from the Distribution Board and 240VAC
from the DIN Rail. The +24VDC powers circuitry located on this board and is reduced to
2-7
Discovery QDR Series Technical Manual
ARD+, ARD-
ATD+ , ATDSYSRESET+,
EMERGENCY+,
MAN_UP*, MAN_UP_RET
MAN_DOWN*, MAN_DOWN_RET
+24V
120V(A)_UP_LEFT
120V(A)_DWN_LEFT
120V(B)_LEFT
GND_PED
+3.0VREF
(Position Signal)
-3.0VREF
120V(A)_UP_RIGHT
120V(A)_DWN_RIGHT
120V(B)_RIGHT
GND_PED
+3.0VREF
(Position Signal)
-3.0VREF
TZ
DRIVE
BOARD
LEFT
PEDESTA L
MOTOR
To/From
Distribution Board
To/From
DIN Rail
Assembly
LEFT
PEDESTAL
POSITION
ENCODER
RIGHT
PEDESTAL
MOTOR
RIGHT
PEDESTAL
POSITION
ENCODER
120V(A)_RIGHT
120V(B)_RIGHT
GND_PED
120V(A)_LEFT
120V(B)_LEFT
GND_PED
+5VDC. The +5VDC is converted to -5VDC and +/-3VDC. The +/-5VDC powers logic
circuitry on this board, while the +/- 3VDC provides the reference voltage for the position
sensors. Two green LEDs provide visual indication of the +24 and +5VDC status (ON
indicates the respective voltage is present).
The 240VAC power is connected through control relays to the pedestal motors.
2.5.3 Interface Connections
Figure 2-4 shows the interconnections between the Distribution Board, the TZ Drive
Board, the Pedestal Motors, and the Pedestal Position Encoders. Table 2-5 describes the
interconnections between the Distribution Board and the TZ Drive Board. Table 2-6
describes the line voltage (240VAC, line to line) between the DIN Rail Assembly and the
TZ Drive Board. Table 2-7 describes the interconnections between the TZ Drive Board
and the two pedestal motors and their respective position encoders. The tables also
identify the interconnection connector and pin assignments.
Table 2-4 shows the interconnections between the Distribution Board, the TZ Drive
Board, the Pedestal Motors, and the Pedestal Position Encoder, Table 2-5 describes the
interconnections between the Distribution Board and the TZ Drive Board. Table 2-6
describes the line voltage (240VAC line to line) between the DIN Rail Assembly and the
TZ Drive Board. Table 2-7 describes the interconnection between the TZ Drive Board and
the two pedestal motors and their respective position encode rs. The tabl es also iden tify the
interconnection connectors and pin assignments.
2-8
Figure 2-4. Distribution Board/TZ Drive Board Interconnection Diagram
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