calibration failure

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TROUBLE SHOOTING GUIDEFOR CALIBRATION FAILURES

September 9, 2003

Calib ration Troubleshooting Guidc

SCANNINGCALIBRATION STANDARD.. ........... IO

Limits Encountered DuringComrnunication Error Displayed During Cal.ibration ..... ............. 13

QC SPINEPIIANTOMMEASUREMENTSNOTWIIIIINSPECIFICATION.................. ...........t4CALIBRAÏONEXAMPLESAPPENDX ............... 15

XDRIFTGRA

AUTOSET.TRC EXAMPLE PRINTOUTAPPENDIX... .................24

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Calib ration Troubleshooting Guide

CALIBRATION OVERVIEW

There are three major operations performed during a calibration: Diagnostics, Scanningthe calibration standard, and the scan of the QC phantom.

The Diagnostics performs test of the PMT's, Íilters, and source before scanning thecalibration standard. lt will display pass/fail for each test performed.

The scanning calibration standard consists of measurements of the 77 steps of plasticand metal combinations, using allthe filters. An initial calibration makes 4 completepasses and takes approximately 6 hours for a scanner equipped with a high speed filterand 12 hours for non-high speed. The daily calibration (performed each day by theoperator) takes approximately 30 minutes. The daily measurements are compared to areference value that is available in CALIB.FIL (created by the initial calibration). lf ameasurement result is out of speciÍication, an eror message will appear on the screen,and the scanner will re-measure that location. lf subsequent attempts still fail, thecalibration will be flagged as'failed'and the enors are stored in an ERRORS.TRC file.Due to the retries, a failing calibration may take more time than usual. lf the calibrationfails, the file CALIB.DBG is created. A failing calibration never affects your CALIB.FIL file.

As part of a daily calibration, the QC phantom is scanned. Precision and Accuracy iscalculated forthe last 16 scans (total numberif less than 16) using the values stored inthe Setup.fil. lf one or more of the scans is out of range a failure will occur.

ALL FAILU RES

1. Printing the enors.trc is the first step to correcting a calibration failure.? lf your system has SFT 1.3.0 or later, select 'bn_trC from page 2 of the XSFT

menu. Make sure your printer is on and ready. This will only print 3 pages of theenors. Normally the first few errors will be the only information that is needed.

'? The DOS type command may also be used to print the entire erors.trc Íile.4-channel: Type 'CD\)(R26\CALTRACE', press Enter, then 'TYPEERRORS.TRC >PRN'.2-channel: Enter'CDXR26', then'ryPE ERRORS.TRC >PRN"

2. Verify the laser is aligned

3. Make sure the stability and the alignment collets have been removed from the upperarm.

4. VeriÍy the source is properly aligned.

5. Verify that Points A and B were marked properly during the calibration procedure.The points must be marked on the Plexiglas and not the metal bracket.

6. Verifo the calibration standard is sitting straight on the tabletop. Verifu the lasertouches the top and bottom edges of the standard simultaneously. Check the frontand side. For XR26 scanners make sure it is hanging straight. Adjust the knobs onthe bracket untilthe standard is level.


Calibration Troubleshooting Guide

7. Verify the calibration standard is not damaged. Shake the standard to see if there areany loose parts. Remove the covers to verify there is no foreign or loose materialinside.

..íJ-l: RE-INSTALL THE CALIBRATIoN STANDARD coVERS coRREcTLY. MAKESURE POINT A IS NO METAL, NO PIÁSTIC CORNER, AND POINT B 1S ON THETHICKEST METAL AND PIÁSTIC CORNER. MAKE SURE THE CROSS MARKS INTHE PLASTIC ALIGN WTH THESE CORNERS.

8. Verify the calibration standard is in the marks on the tabletop. lt must fit within thewindow that is cut out of the tabletop (this is only visible under the tabletop).

9. For an initial calibration veriff the only item on the tabletop is the calibration standard.The tabletop is measured as part of the calibration and no other items can be on thetable.

10. Make sure the parameters have been properly entered on the Service Setup screênFor 2-channel also make sure the conect configuration has been selected, (high vsnormal speed, high vs low intensity).

2 -11 . For XR26, Eclipse, and XR36 scanners with a motor driver board 387A017 , venfy a

<;i Motor Driver Board Shield is installed.

/' 12. Check for radiation leaks from the source; add lead as required. For 2-channel, afailing spine or rough body scan on a normal speed scanner or a failure for a highnumbered Íilter on a high speed scanner may be an indication of a radiation leak fromthe source. Perform the Radiation Leakage Test in the 3885631 Repair Procedure.

DIAGNOSTICSDuring the first segment of an Initial and Daily Calibration, a spectrum of the PMT isdisplayed, the discriminators are set, background radiation is measured, and diagnostictests are performed for the reference beam, the shutter, high attenuation filter, mediumattenuation filter, low attenuation Íilter, and dynamic filtration (HS scanners only). Thesoftware expects to detect a certain amount of Low Energy and a certain amount of High-Energy counts with each shutter or filter in place. Refer to the Low / High Energy Countsin the General Troubleshooting Guide for an explanation of count rates.

The file DIAGNOST.TRC contains all the information gathered during this section of thecalibration.

? The DOS "type" command may be used to print the entire diagnost.trc file.o 4-channel: Type 'CDU(R26\CALTRACE', press Enter, then "TYPE

DIAGNOST.TRC >PRN".o 2-channel: Enter'CD\)(R26'. then 'TYPE DIAGNOST.TRC >PRN"



EXAMPLE OF A 24HANNEL DIAGNOSTIC SCREEN

EXAMPLE OF A 4CHANNEL DIAGNOSTIC SCREEN

DiscriminatorsTypically the 2-channel discriminators are less than 100. lf they are more it may indicatea defective PMT or grounding problem.

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For 4-channel the discriminators are normally between 1 100 and 1700. Discriminatorsettings are the DAC values set by the software to separate the high and low energy in

each PMT and eliminate the noise. Final refers to the top PMT (high energy), and Initial

refers to the bottom PMT (low energy). On the printout, FH=Final High, FL=Final Low,

lH=lnitial High, lL=lnitial Low. (See printout below.) For systems with host software 3.9.5or higher the Peak Values will also be displayed. For QS host software 3.0.0 to 3.9.4 thepeaks can be displayed by performing a Diagnostic peak from PeakPick of the XSSTmenu. The Peak is the DAC setting that coresponds to the highest point on thespectrum. The finalpeak (high energy PMT) should be between2200-2300, and the peak

for the initial tube (low energy PMT) should be between 1 100-1200. lf they are out ofrange then refer to the 3885631 Repair Procedure to adjust the PMT Gains. An initial

calibration must be performed afler a gain adjustment.

lf the message "Discriminators Out of Range' is displayed for QS Host Software, verifythe discriminators are within the following ranges:

Verify the PMT spectrum is normal and does not indicate a defective PMT. Referto theCalibration Example Appendix of this Calibration Troubleshooting Guide.

The following is an example of a calibration failed because of a High-Energy PMT withouta "Ghost" peak and using XR v3.1.3 Host Software.

lf, (rlibrrtion UrrsÍon 3.1,1 98 Noecnber 9ó

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- ftIibrrtioa (onplatr -TÍm f,enainins ïhis PhEscl 0rB8:t!0Íotal line ten:ining; 0tl4t27

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You can visibly see there is no "ghost' peak at the anow and the discriminator for FH isat 610 instead within the specifications of 1024-2560. Install host software 3.9.5 or higherif compatible with the scanner hardware, otherwise replace the high energy PMT.

FH FL IH IL

1024 - 2560 96-512 1024-3072 96-512Max chanqe - 250 60 300 40

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AutoSetThis is performed during the diagnostic tests for a daily and an initial calibration beforethe peak spectrum is displayed, and often displays "Retrying'.

All XR46 and Excell Scanners with 9N 1600 or higher have autoset hardware, or refer tothe Autoset Detection section.

,i./. i: REFER TO THE 9005007 - Autoset Signal Flow - seleci the appropriate scannertype

1. The autoset information from the Host software is stored in C:XR26\Caltrace\Autoset.trc, and Autoset.his. These file should be printed and sent to Norland foranalysis.

2. Perform the XSST "PAutoset -R" and then print a peak to see if the peak values areset correctly at2250 and 1 150. Refer to the 3885631 Repair Procedure for moredetails on setting the discriminators. flhe XSST autoset and host software autoset areindependent and do not have shared file. Performing the XSST autoset will only aid indetermining the failure and not fix the host software error.) These values are stored inthe XR26\Service\pautoset.trc file. Make sure beam path is clear of all objects exceptthe tabletop.

3. Measure the voltages on TP2 and TP3 fIP1 is ground) on the Autoset board whilePAutoset - R is running. Verify the voltages are changing. lf they are not then autosetis not working and the wiring should be óecked. lf they are changing then check thefilters to make sure they are working conectly.

4. Wiring:4.1. First of all check the wire connectors on the Laser Power Supply board:

P1 Pin 4=Purple, Pin S=Brown, Pin 6=TanP3 Has no connectorP4 Red on Top and Yellow on BottomP5 Red To Left (when standing in the back of the scanner)P6 Orange on left and Gray on Right side (when standing in the back of thescanner)

4.2Venty the 4 connectors on the Photon Integrator Board:4.2.1 . The two pin connector under the Photon board that connects to TPS and

P6 of the main board. Blue wire to TP5 goes towards the front of thescanner and the green wire to TP6 goes to the back of the scanner.

4.2.2The main connector that attaches the Photon board to the main board.Verify it is not one pin off.

4.2.3 P3- pin 1=Yellow (to the left when standing in front of the scanner), pin2=Gray (to the right when standing in front of the scanner).

4.2.4.fhe ribbon cable on P2 goes to P9 of the Main Board. The red stripeshould match the red color dots. (To the right when standing in front of thescanner.) Verify it is not one row off.

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5. The peaks may be manually adjusted if autoset fails using the "PMTVOLT -ixxx -fxxx", where xxx is the voltage values for initial (IP3) and Íinal (IP2). Previous valuesfor the scanner can be obtained from the C:D(R26\Caltrace\Autoset.his. Perform a

diagnostic peak to view the spectrum and the peak values. lf they are not conect then

adjust the voltages until 2250 and 1150 values are achieved. Measure the voltages on

TP2 andTP3, using TP1 as ground on the Autoset Board. The measured voltageshould be the same as the voltage entered in the above command.

6. Veriff 15 volts is getting to the Laser Power Supply Board. Measure the voltages Pin 5

-Brown wire (-15v), Pin 6=Tan wire (+15) on P1 of the Laser Power Supply Board.

7. Verify the 5 volt is being generated on the Laser Power Supply Board. Measure Pin 4

of P2 of the Laser Power Supply Board.

BackgroundFor all system the background is normally less than 10. This measurement is of theradiation or noise being detected by the PMT's without the shutter open. lf it is hígher then

10 veriÍy that no other sources of radiation are close to the scanner, such as another x-ray device or any nuclear medicine patients or material. This may also be caused by a

bád ground connection such as the one on the upper assembly orthe source, or noisycomponents such as a PMT.

Reference Beam and FiltersThe reference beam is a measurement through a specific step of the metal and plastic

as determined by the software. lf this measurement fails then refer to the 3885631Repair Procedure to perform a Source Count Rate check. The actual count rate can be

viewed in the C:XR26\CALTRACE\DIAGNOST.TRC for 4-channel scanners . For 2-channel scanners the file is C:XR26\DIAGNOST.TRC. lf there are no or low counts referto the general Troubleshooting section of this guide. For 2-channel, make sure thecorrect parameters have been selected in the Service Setup (high intensity, lowintensity). Wren the Service Setup is configured for High Speed, High lntensity theReference Beam count rate ranges are: High=l79,000 - 691,000 ll Low=269,000 -1,058,400. The count rate range for Low Speed, High Intensity Reference Beam the

values are : H igh= 1 72,000-6 1 9,000 // Low=269,000-968,000.

lf the reference beam fails the x-ray off, then the shutter may also fail because they are

based on the reference beam measurement. But it is probably a problem with thereference beam count rates and not the shutter.

lfjustthe shutterfails verify proper operation of the micro switch on the filter casting and

the wiring from the shutter to the main board. For more details refer to the general

Troubleshooting section of this guide. Replace the Íilter assembly because the shutterarm thickness may be too thin.

Dynamic Filtration Errors

1. Perform the Filter Test in the 3885631the board and filter are a matched set.

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Repair Procedure. lf this fails the make sureReplace the filter assembly.


2. lf the filter test graph is U-shaped versus the normal L-shaped then check thefollowing:

\Mren the filterarm moves in and out of the beam there is an acceleration pulse sentand then a brake pulse. lt may be that the brake pulse is not be sent and the arm isbouncing. There are 3 separate circuits on the board - one for each arm.FilterArm 3 - brake pulse TP12 - acceleration pulse TP13 controlled by U12.Filter Arm 2 - brake pulse TP6 - acceleration pulse TP7 - controlled by U6.Filter Arm 1 - brake pulse TP2 - acceleration pulse TP3 - controlled by U1.

Ground = TP16

Run the filter test from the XSST menu. Run each filter separately by entering thefilter number instead of A forAll. \Mrile the arm is moving then look at the signals onthe conesponding test point. lf possible use a dual probe attach one to theacceleration pulse and one to the brake pulse. The acceleration pulse will lead thebrake pulse. Set the scope to 2 ms/div, and 1vldiv. The signalis about 5 volts inamplitude and 4.5 ms. Compare the signal for the defective filter arm to the other two.

View the signal for an extra pulse on the filter arm that is failing. Also listen for theextra click.

For the defective arm try to change the corresponding lC to see if the problem movesto the other arm. For example if filter arm 3 is failing then change U12 (filter arm 3)for either U6 (Íilter arm 2)or U1 (filter arm 1). All the lC's are in a socket. See if theproblem moves to the other filter arm. Make sure to mark the lC's with the originallocation so it can be returned to the original configuration. lf U15 (filter 3), Ug (filter2),and U3 (filter 1) are in a socket also try to exchange them.

3. Power-cycle the computer and scanner and restart the calibration.

4. Make sure the Filter Motor Driver Board and filter assembly have the same serialnumber. They are matched at the factory and cannot be interchanged.

5. Verify the ground wire going to the source is securely fastened.

6. Print the DIAGNOST.TRC, DF3.TRC, and DF4.TRC immediately afier the failure foranalysis.

For 4-channel scanners enter the following commands:Cd\x126\caltraceType diagnost.trc >prnType df3.trc >prnType df4.trc >pm

For 2-channel scanners enter the following commands:Cd\xr26Type diagnost.trc >prnType df3.trc >prnType df4.trc >pm

7. For 2-channel: lower the PMT gains to 3.5 Volts.


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9.


For 2-channel: at full power and over an open area of the table, perform the PEAKprogram and record the values. Then run SNPEAK and follow the on-screenprompts, except do not use the lead. Record the values. lf there is a difference ofapproximately 40 or more, replace the low energy PMT, if lowering the gains does notconect the failure.

For 2-channel: upgrade any High Speed systems that have Main Board 3884004 toEPROM Rev 1.3.1 to take advantage of improvements in sampling software code.

10. For2-channel, make sure the parameters have been properlyentered on the ServiceSetup screen (high speed, high intensity).

1 1. For 2-channel, if an lnitial Calibration will not pass after a HS upgrade. A Mark l, Lowlntensity, Low Speed scanner must first be upgraded to a Mark ll, High Intensity, LowSpeed system before attempting a High Speed upgrade. The attenuator plug must beremoved from the well of the Lorad source.

12.For XR26, Eclipse, and XR36 scanners with a motor driver board 387A017, verifo aMotor Driver Board Shield is installed.

SCANNING CALIBRATION STANDARDThe origin of calibration failures can be found in a wide range of causes or a combinationof several.

During an initial or dai|y calibration when an error occurs, the software automaticallyretries the failed calibration standard measurement.

For 4-channel do not terminate the calibration if the .Status" in the lower left comerindicate "Retrying". lt will re-measure the failed steps of the calibration standard. lf it isnot successful then the Status will indicate 'Failed'.

For 2-channel do not terminate the calibration if enors are displayed in the lower leflcorner. The software will retry the measurements. lf the retry is successful, the originalerror message remains on screen and the calibration will continue. lf the retry is notsuccessful (i.e. the calibration has failed), the original message remains on thecalibration screen, or is updated with additional eror messages, untilthe message'CALIBRATION ERRORS DETECTED' is displayed on the lower right side of thecalibration screen, indicating a failed calibration.

Enors will be stored in the ERRORS.TRC file. The fileC:XR26\CALTRACE\ERRORS.TRC (2-channel C:XR26\ERRORS.TRC) contains allthe error messages generated in the last calibration. lt is an ordinary text file. Enter'TYPEERRORS.TRC' while in the conect directory to view the file. Detailed instruction forprinting the errors is listed below.

lf a new calibration is started, the contents of ERRORS.TRC will be cleared and any newerror messages will be written to the file. For 4-channel systems a history of all the failureis stored in the C:D(R26\CALTACE\ERRORS.HIS, and may be viewed at any time. Aftera problem is fixed, Norland recommends deleting this file. To delete the file typeCDXR26\CALTRACE, press enter, type DEL ERRORS.HIS, and press enter. For 2-channel scanners the history of enors is not saved.

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Printing the Errors.trcPrinting the errors.trc is the first step to correcting a calibration failure.

? lf your system has SFT 1.3.0 or later, select bn_trC from page 2 of theXSFT menu. Make sure your printer is on and ready. This will only print 3pages of the erors. Normally the first few enors will be the onlyinformation that is needed.

? The DOS type command may also be used to print the entire enors.trcfile.

o 4-channel: Type 'CDXR26\CALTRACE', press Enter, then"TYPE ERRORS.TRC >PRN'.

o 2-channel: Enter "CDU(R26", then 'TYPE ERRORS.TRC >PRN'

Pass to Pass ErrorsThis erorwill only happen on an initial calibnation. The77 step wedge is measured fourtimes during the initial calibration. lf the count rate is different from pass to pass it willdisplay this error.

Pass to Pass Error Example

Excessive variation from pass I to pass 2.

Filter=O, Metal=3, Plastic=7, Detector=lActual couttts (H/L) = 237495 -2.2%Expected counts = 242885 +l- 3.490Á

Allowable ranse = 234397 - 251373

139765 3.96Yo

13444t +/- 3.66yo

t29515 - 139368

Explanation ofvalues:(The filter nurnber, the metal step, and the plastic step are displayed.)

\Filter:O, Metal=3, Plastic=7, Detector= I (Always displays I because the detectorsare stacked and not side bv side.)

(The frrst colurnn is the surn of the high energy cgunt rate frorn the final and initial tube.)(The second colurnn is the surn of the

f ow energy count rate,frorn the hnal and initial tube.)vv

(measured corurts)Actual counts (H/L) = 237495 -2.2% 139765 3.96yo

Expectedcounts = 242885 +l- 3.49Yo 134441 +L3.66yoAllowable range = 234397 - 251373 129515 - 139368

1. Veri[t the tabletop or the calibration standard has NOT been moved after markingpoints A and B. Norland strongly recommends posting "Do not distuó-xrays arebeing emitted" signs while running the initial calibration.

2. Perform a stability test with the source cooled to room temperature - the source maybe drifting or arcing, replace the source.

3. Perform a table test - count rate differences at different locations will cause thecalibration to fail, level the table or make sure the cabling is secure.

4. Make sure the source fan is working or the count rates will drift.

5. Compare cold peak values to peak values after a system is warmed up to see if thereis a gain drift.

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6. Perform a skiptest - missing steps could cause the x-ray beam to be in the wronglocation on the calibration standard. Failed skiptest could indicate a defective motor,motor driver, main board, cabling, or something blocking the arm movement.Another way to veriff the scanner ls not missing steps is do not move the calibrationstandard or do not shut off the scanner. Terminate the current calibration. Re-enterthe Host Software. DO NOT find Table Origin. DO NOT shut off the scanner. DONOT initialize the system. Restart the calibration. Verify the laser is automaticallypositioned over points A and B on the calibration standard. lf not, the scanner isskipping steps. Note which axis is affected before proceeding.

Timeout Waiting for CountsThis enor can occur during a daily or an initial calibration.Enor Example:

Tirneout waiting for counts on standard.Filter=7, Metal=5, Plastic=0, Pass=4

Minirnurn counts :345658

Maxirnurn tirne (Sec) :200.0

Minirnurn coullt rate :5761 #Before CorrectionActual count rate (Det 1) : 0, 0, 0, 0 # After Correction

This means no counts are being detected. Refer to the No Counts section of the GeneralTroubleshooting Guide for details.

Residual ErrorsThis error can occur during a daily or an initial calibration. Basically it means themeasurements of the steps do not fit the polynomial equation. Verify the calibrationstandard is not damaged, it is in the proper position, and sitting level on the table. Checkthe PMT spectrum to verify the PMT's are good, refer to the Calibration ExamplesAppendix of this Calibration Troubleshooting Guide procedure. Perform a skiptest,stability test, Íilter test, and table test. Veri[t the background counts for 4-channelscanners are less than 12.

Correction Factors or Drift ErrorsDuring a daily calibration there are many comparison checks.

The correction factor is dividing the current calibration values by the running average ofpast calibrations or the initial. lf the values are perfectly matched then the conectionvalue is one. lf the difference is too great that means the count rate difference betweenthe cunent calibration and the running average is too great.

Drift errors are comparing the current calibration to the initial calibration. The following isan example of an error message relating to a 2-channel drift enor:

"The counts 379800 at plastic 0, metal 0, for filter 6, low energy, have drifted 10.5%from the reference counts 360,000. The maximum allowable is 10%'

1. Print the C:XR26\CALTRACE\Drift.his file (2-channel C:XR26\CALDRIFT.TRC), byselecting Xdrift from page 2 of the XSST menu, rev 1 .3.1 or higher (2-channel enterSERVICE, the type XDRIFT). When prompted press any key to display the graph.After the graph is displayed press P to print.



NOTE: lf the message appears 'lnvalid European data in Íile' the CALDRIFT.TRC filemust be edited, using any type of DOS editor. This is caused by changing the datefrom European to USA in host software Preferences under lhe Setup menu.

To analyze the graphs refer to the Xdrift Graphs Appendix of this CalibrationTroubleshooting Guide.

2. lf the conection factors or drift is not severe a new initial calibration may fix theproblem. However the system should be monitored to verify the failure does notoccur in the near future.

3. Check the PMT spectrum, stability test, and filter tests.

Limits Encountered During CalibrationDuring an initial calibration the system measures the tabletop. The scanner arm maycome in contact with one of the limit switches during an initial calibration. lf an enor dumpoccurs (blue screen background) press enter to print the enor. lf the screen has been bybypassed the enors are stored in the C:\XR26\ERRORS.LOG Íile. To print the contentsof this file enter 'CD\)(R26" to óange to the XR26 directory, then enter 'TYPEERRORS.LOG >PRN'and press enter.

1. ALWAYS FIND TABLE ORIGIN AND FIND TABLE DIMENSIONS, BEFORE ANINITIAL CALIBRATION.

2. Verify the arm has clearance around the entire table area.

3. Verify the position of the Main Cable in the bottom of the scanner.

For XR26: Make sure it is positioned properly around the guideposts.

Make sure the cable is bracketed to the scanner in such a way that the MainCable is not restricting arm travel.

4. Veriff the arm moves freely on the rails. Any excess friction can cause the scanner tomiss steps and encounter a limit switch. lt may be necessary to oil the rails. Do notuse any lubrication with a degreaser such as WD40. Use light machine oil such as 3in 1.

Communication Error Displayed During Calibration1. You will have the option to retry if this situation occurs. Select the RETRY option to

continue the calibration. The RETRY command first sends the scanner arm to locateits origin, and then continues on with the calibration from the point where it receivederrors.

2. lf the RETRY option fails, tum off the scanner power, tum it back on, and selectRETRY again to continue.

WARNING!! DO NOT SHUT OFF THE COMPUTER - ONLY TURN OFF THESCANNER.

3. lf the system still does not respond, tum the computer and scanner off. Tum thepower back on and restart the calibration process. lf errors continue to occur, refer tothe No Communication section of the GeneralTroubleshooting Guide.



QC SPINE PHANTOM MEASUREMENTS NOT WITHINSPECIFICATIONFor host software 2.3 or later a measurement of the Quality Control Phantom (QCPhantom) is part of the Daily Calibration routine. The precision and accuracy results ofthis scan(s) are displayed graphically on the QA screen. Refer to the Operato/s Guidefor detailed information about the precision and accuracy wamings. lndividual QC scanresults are stored in the file C:XR26\QC.FIL, or for software versions 3.9.5 or laterC:XR26\NRLD_QC.FlL.

Also displayed is the numerical information regarding the BMC and BMD (optionalfat andlean) values for the most recent QC Phantom scan, the average of the last 16 scans,and the entered values.

1. To view these files type XD_QC at the C:tr prompt. To view the fat and lean valuesenterXD_QC -T.

2. To delete any invalid scan, type XD_QC -Dxxx, where xxx is the record number of theinvalid scan.

3. Verify the conect information has been entered into the service setup screen of thehost software. The calculations for precision and accuracy are based on theseentered values.

4. Verify a final factor has been set. Refer to the 3885631 Repair procedure for details.

5. VeriÍy the QC phantom has been placed on the table conectly and marked in theproper order.

6. Verify the last 16 scans are valid. The calculations are based on the last 16 scans. lfsome of those measurements are significantly different then the precision andaccuracy for the last scan will be affected. Delete all bad values or start a new QCfile. To rename the existing file enter CD XR26 to change to the XR26 directory, forhost software revision <3.9.5 enter REN QC.FIL QCMMDD.FIL (where mmdd is themonth and day), and for host software revision 3.9.5 or later enter RENNRLD_QC.FIL NRLDMMDD.FIL (where mmdd is the month and day).

7. Perform a skiptest to verify proper arm movement.

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CALI BRATION EXAMPLES APPEN DIX

This appendix will give examples of calibration screens and peak graphs showing

Oiff"*hï passed or taiteO calibrations and why they are as such'

The following is an example of a passing initial calibration using XR v3.5.0 Host softrare'

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Shutter'tr{"**m,'fitter1{dilirn Íttra;'FiJterllish {tten, Filter&nanir Filtrarim

talibrrtion'Statusi lll ?ROÊRSS

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i

prtss (Erc) toTPminat!

-(alitrrtion

l-íànceil

The following is an ex using.4-channel Host software'

The Daily Càlibration in tÀi. versión of 6f-Mare does not print the entire peak graph.

Í[ Éalibretion ltersion 3.5,8 05 June 9?

[alibntíon itrtus: IN PR[6RE55

Í)AILY CALIBNSIIÍH

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- Scrnning (alihration Standerd -

Iire Renaining This Phare: Q:Qí:89ioïil iín RefuÍning: B:81:tl9

Prrss (Esc) toTtrdnate [rlibration

fGncerl

Norland, a CooPerSurgical ComPanY


The following is an example of an initial calibration failed because of bad Low-EnergyPMT. You can visibly see there is no high-energy peak at the anow

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ftIibrrtion Status:

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lTi'tÊin

Referenca Beantrry OffShutterl-os Atten. Filterf{Bdiun f,ttÊn, FiltFrHish Atteo, FilterOynrnic FiltntÍott

This is an example of a bad high energy PMT. Unable to adjust it.

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Norland, a GooperSurgical Company


Example of a defective high energy PMT because of the spike.

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XDRIFT GRAPH APPENDIX

The following pages represent graphs printed from the XDRIFT program' The graphs

represent long term count raté àhang"t tntt are stored for each daily and initial

calibration performed. The Íiles are stored in the C:XR26\CALTRACE\DRIFT'HIS for 4-

channel scanners, rno c'xnz6\cALDRIFT.TRC for 2-channel scanners'

By the change in the graphs, Y.ou can recognize certain problems during your calibration'

Keep in mind when yóu view these grapÈïÀát tn" change in a graph may have several

causes, not just oná. Th.r. may bà several reasons wÀy the graphs changed as they

did.

The following examples are 2-channel images' however,the troubleshooting principles

are the same for 4-channel. The major Jiriá"no is the 4-channel graphs have 4 lines,

FH (Finat High = nig; Ë;Ëó counts íor the top PMT), FL (Final Low = low energy counts

forthe top pMT), lH (lnitial High = the higÀ ilggt counts'forthe bottom PMT)' lL (lnitial

Low = the low energy counts for the bottom PMT)

Analyzing the Xdrift GraPh

XDRIFT EMMPLE 1

one PMT',s count rate is drifting faster than the other. The majgl c-a9se is a defective

pMT. A Charge nmïrin.i áó"iO-ot Bias Board could also cause this failure'

XDRIFT EMMPLE 2

Both PMT's are drifting lower at the same rate'

1. Defective High Voltage Board. check the gain adjustment to verify the high voltage

has not decreased. Readjust tfre gai;i ir n"-".rt"ry. Monitor the system to verify this

fixed the Problem.

2. Oil may be leaking into the source well. This is most common for a Lorad source

(source Sn',f .fódO) Check by removing the filter casting assembly' Adding a

desiccator kit (Lorad only) may retieve some pressure, but the system must be

monitored to veiity the desiccator kit fixed the problem'

3. The filter casting may be changing characteristics' change from a samarium pellet to

a samarium foil filter casting assembly'

Scanners with samarium pellet filter castings:

MARK I

MARK II

s/N <4064s/N <826

MARK II HS, XR-30 S/N <2010

Eclipse s/N <3007

4. Lorad sources only: there may be internal leakage cunent due to oil contamination'

check by measuring between TP2 and TP24 on the x-ray source control board with

the source set at 1gÓKeV and gmA. To do this, type 'SERVICE'and then VC 100 0'' lf

there is more than 50mV to the source, there á'ay be leakage cunent. Do not leave

the source at tufi voltage and zero cunent any longer than necessary' This may

cause damage to the source'


a

I

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l-I

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XDRIFT EMMPLE 3

|ftherearespikesintheCALDRIFTgraphthismaybeduetothethermalinstabi|ityofthesource or Íitter casting. Perform a

"oiJ

-ttàÉlity test, filter test' and check for

defective/inte rmitte nt wirin g'

XDRIFT EMMPLE 4

It appears that the count rate is unstable for all channels' This scanner was failing daily

catibrations. perronrià';;il-t liour stability i.it to ve5r.fu ine.,-source is stable' Perform a

fitter test to verify th;Íiit.;are workinj'co1199tly, Vórify..tfre calibration in the correct

place on the tabte ".á

iÀàV "t mart<ing.,ine

iX' in ih" plaótic.and not the 'A' or 'B' on the

metat bracket. lf tne lairyï;t;.; ;neiit is warmed up then it may be a thermal problem

that should be detected by the stability.test' Verify there..are not extemal environmental

issues, rike power oi'ánolÉ.ii-ray oevicé. Verifythe cafibration standard sit straight on

the table. Use the rar.i to verify it is siiaight, tÉe lase.r should hit the edge of the top

cover and the edge of the bottom .ou"t rirn,ittaneously. lf it is not straight the x-ray beam

could be hitting the first step instead. of lfte óp"n ar"á for point 'A'' Run a table test to

verify the lower cable Ë gà.0 Use the À1óttpàgom and ilex cables to see if the count

rates droP.




XDRIFT EXAMPLE

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XDRIFT EXAMPLE 2

94138/'1997 15:53 414-563-9626

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AUTOSET.TRC EXAMPLE PRINTOUT APPENDIX

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calibration failure

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