Calibration Failure

(1)

a

So$persurgical

Ëam

psny

TROUBLE SHOOTING GUIDE

FOR

CALIBRATION

FAILURES

(2)

Calib ration Troubleshooting Guidc

SCANNINGCALIBRATION

STANDARD..

... IO

Limits Encountered During

Comrnunication Error Displayed During Cal.ibration

...

... 13

QC SPINEPIIANTOMMEASUREMENTSNOTWIIIIINSPECIFICATION... ...t4

CALIBRAÏONEXAMPLESAPPENDX

... 15

XDRIFTGRA

AUTOSET.TRC EXAMPLE

PRINTOUTAPPENDIX...

...24

(3)

Calib ration Troubleshooting Guide

CALIBRATION OVERVIEW

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

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

The scanning calibration standard consists of measurements of the 77 steps of plastic and metal combinations, using allthe filters. An initial calibration makes 4 complete passes and takes approximately 6 hours for a scanner equipped with a high speed filter and 12 hours for non-high speed. The daily calibration (performed each day by the operator) takes approximately 30 minutes. The daily measurements are compared to a

reference value that is available in CALIB.FIL (created by the initial calibration). lf a

measurement 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, the calibration 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 calibration fails, 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 is calculated

forthe

last 16 scans (total numberif less than 16) using the values stored in

the 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 the

enors.

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

'TYPE

ERRORS.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 upper arm.

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

laser touches the top and bottom edges of the standard simultaneously. Check the front

and

side.

For XR26 scanners make sure it is hanging straight. Adjust the knobs on

the bracket untilthe standard is level.

(4)

Calibration Troubleshooting Guide

7.

Verify the calibration standard is not damaged. Shake the standard to see if there are any loose

parts.

Remove the covers to verify there is no foreign

or

loose material inside.

..í

J-l:

RE-INSTALL THE CALIBRATIoN STANDARD

coVERS

coRREcTLY.

MAKE SURE POINT

A

IS

NO METAL, NO PIÁSTIC CORNER, AND POINT

B

1S ON THE THICKEST METAL AND PIÁSTIC

CORNER.

MAKE SURE THE CROSS MARKS IN

THE PLASTIC ALIGN WTH THESE CORNERS.

8.

Verify the calibration standard is in the marks on the

tabletop.

lt

must fit within the window 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 the table.

10. Make sure the parameters have been properly entered on the Service Setup screên For 2-channel also make sure the conect configuration has been selected, (high vs normal 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, a

failing spine or rough body scan on

a

normal speed scanner or a failure for

a

high numbered Íilter on a high speed scanner may be an indication of a radiation leak from the source. Perform the Radiation Leakage Test in the 3885631 Repair Procedure.

DIAGNOSTICS

During the first segment

of an

Initial and Daily Calibration,

a

spectrum

of the

PMT is

displayed, the discriminators are set, background radiation is measured, and diagnostic tests are performed for the reference beam, the shutter, high attenuation filter, medium attenuation filter, low attenuation Íilter, and dynamic filtration (HS scanners only). The software 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 Counts in the General Troubleshooting Guide for an explanation of count rates.

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

?

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"

(5)

EXAMPLE OF A

24HANNEL

DIAGNOSTIC SCREEN

EXAMPLE OF A 4CHANNEL DIAGNOSTIC SCREEN

Discriminators

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

rtr

C 0

I

T

I

a

Í

t

I

0iscriristr {3

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Sedgrourd ó

g

lcftrucr

&rr

-

Ptss

Shuttrr

-

f:ss ligir

_lttn.

Íilter

-

Prss

ltrÉi,ul rlnen.

Filur

-

P:ss

br

lttu. Fil,ur

-

P:ss

bily

ftIilr:tioe

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lirr krinint

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Fsr

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filtrr 4

lor

tmrt,

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rllorrbk

ilGI]

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{.tl tr

rrd

srim. i

l\

/1

/\

/i

lr

t

l,lR lalibration Uersion 3,5.0

6

June 9?

c 0 U N T n n T E

CalÍhntion Strtus: ll{ PISRESS

DNI[V TOLIBNATIÍI{

ff,rt,lI,lt

0iscrininator'1X6,,221,1284,177

Brckground

5,8,8,2

Reference

Bean

PASS

ïray

Off

PA55

Shutter

PASS

Lou Atten,

tilter

PA55

líedÍun fitten.

tilter

PA55

Hish Ítten,

tilter

PASS

Oynanic

FíItretion

PA55

- ScrnnÍng [elÍbrution Standard

-Iioe lanainins This Phrse: E:81:0

Iotrl lire

Reraining:

0:81:09 Press <f5c> to Tarrinate Írlibration

|-(ficel-l

(6)

,. /:.'. -7

V "i.1> ->

.'

u.

Í,

_'t-4"

-*,

"'

For 4-channel the discriminators are normally between 1 100 and 1700. Discriminator settings 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 3.9.5 or higher the Peak Values will also be displayed. For QS host software 3.0.0 to 3.9.4 the peaks can be displayed by performing a Diagnostic peak from PeakPick of the XSST menu. The Peak is the DAC setting that coresponds to the highest point on the

spectrum. 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 of range 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, verify the discriminators are within the following ranges:

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

The following is an example of a calibration failed because of a High-Energy PMT without a "Ghost" peak and using XR v3.1.3 Host Software.

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

(rlibrrtian Status: DEItï (ATISRATIO{ Fil,rt,ilr,

lI

Oiscrininator 61AJ56,1632,216 B:clgmund Reíerrnca 0err Xrry Off ShuttËr Lor ftten,

tíltrr

llprliun àttetr.

tiltrr

llish ltttn.

Íiler

0yiedc Filtntior

- ftIibrrtioa (onplatr

-TÍm f,enainins ïhis PhEscl 0rB8:t!0

Íotal line

ten:ining;

0tl4t27

Fress (Esc) to

krnlnrtr (rlíbrrtiol

nsttËT1

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

FH FL IH IL

1024 - 2560 96-512 1024-3072 96-512

Max chanqe

_-

250 60 300 40

(7)

AutoSet

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

All XR46 and Excell Scanners with

9N

1600 or higher have autoset hardware, or refer to the Autoset Detection section.

,i.

/.

i:

REFER TO THE 9005007

_-

Autoset Signal Flow

-

seleci the appropriate scanner type

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 for analysis.

2.

Perform the XSST "PAutoset -R" and then print a peak to see if the peak values are set correctly at2250 and 1 150. Refer to the 3885631 Repair Procedure for more details on setting the discriminators.

_flhe

XSST autoset and host software autoset are independent and do not have shared file. Performing the XSST autoset will only aid in

determining the failure and not fix the host software error.) These values are stored in

the XR26\Service\pautoset.trc file. Make sure beam path is clear of all objects except the tabletop.

3.

Measure the voltages on TP2 and TP3

_fIP1

is ground) on the Autoset board while PAutoset - R is running. Verify the voltages are changing. lf they are not then autoset is not working and the wiring should be

óecked.

lf they are changing then check the filters 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=Tan

P3

Has no connector

P4

Red on Top and Yellow on Bottom

P5

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 the scanner)

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 the scanner 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), pin 2=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 stripe

should match the red color dots. (To the right when standing in front of the scanner.) Verify it is not one row off.

(8)

I

5.

The peaks may be manually adjusted if autoset fails using the "PMTVOLT -ixxx -f xxx", where xxx is the voltage values for initial (IP3) and Íinal

(IP2).

Previous values for 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 voltage should 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.

Background

For all system the background is normally less than 10. This measurement is of the radiation 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 noisy components such as a PMT.

Reference Beam

and

Filters

The 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 3885631 Repair 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 refer to the general Troubleshooting section of this guide. For 2-channel, make sure the correct parameters have been selected in the Service Setup (high intensity, low intensity). Wren the Service Setup is configured for High Speed, High lntensity the Reference 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 the reference 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

shutter arm thickness may be too thin.

Dynamic Filtration

Errors

1.

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

Norland, a CooperSurgical ComPanY

Repair Procedure. lf this fails the make sure Replace the filter assembly.

(9)

2. lf

the

filter test

graph

is

U-shaped versus

the

normal L-shaped

then

check the

following:

\Mren the filterarm moves in and out of the beam there is an acceleration pulse sent and then a brake pulse. lt may be that the brake pulse is not be sent and the arm is

bouncing. 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 the filter number instead of A forAll. \Mrile the arm is moving then look at the signals on

the conesponding test point. lf possible use a dual probe attach one to the

acceleration pulse and one to the brake pulse. The acceleration pulse will lead the brake pulse. Set the scope to 2 ms/div, and 1vldiv. The signalis about 5 volts in

amplitude 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 the extra click.

For the defective arm try to change the corresponding lC to see if the problem moves to 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 the problem moves to the other filter

arm.

Make sure to mark the lC's with the original location 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 serial number. 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 for analysis.

For 4-channel scanners enter the following commands: Cd\x126\caltrace

Type diagnost.trc >prn Type df3.trc >prn Type df4.trc >pm

For 2-channel scanners enter the following commands: Cd\xr26

Type diagnost.trc >prn Type df3.trc >prn Type df4.trc >pm

7.

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

(10)

L

9.

For 2-channel: at full power and over an open area of the table, perform the PEAK program and record the values. Then run SNPEAK and follow the on-screen prompts, except do not use the lead. Record the values. lf there is a difference of

approximately 40 or more, replace the low energy PMT, if lowering the gains does not conect the failure.

For 2-channel: upgrade any High Speed systems that have Main Board 3884004 to EPROM 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 Service

Setup screen (high speed, high intensity).

1 1. For 2-channel, if an lnitial Calibration will not pass after a HS upgrade.

A

Mark l, Low lntensity, Low Speed scanner must first be upgraded to a Mark

ll,

High Intensity, Low Speed system before attempting a High Speed upgrade. The attenuator plug must be removed from the well of the Lorad source.

12.For XR26, Eclipse, and XR36 scanners with

a

motor driver board 387A017, verifo a

Motor Driver Board Shield is installed.

SCANNING CALIBRATION

STANDARD

The origin of calibration failures can be found in a wide range of causes or a combination of several.

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

For 4-channel

do

not terminate

the

calibration

if

the

.Status"

in

the

lower left comer indicate "Retrying". lt will re-measure the failed steps of the calibration standard. lf it is

not successful then the Status will indicate 'Failed'.

For 2-channel do not terminate the calibration if enors are displayed in the lower lefl corner. The software will retry the measurements. lf the retry is successful, the original error message remains on screen and the calibration will continue. lf the retry is not successful (i.e. the calibration has failed), the original message remains on the calibration screen, or is updated with additional

eror

messages, untilthe message 'CALIBRATION ERRORS DETECTED' is displayed on the lower right side of the calibration screen, indicating a failed calibration.

Enors will be stored in the

ERRORS.TRC

file. The

file C:XR26\CALTRACE\ERRORS.TRC (2-channel C:XR26\ERRORS.TRC) contains all the error messages generated in the last calibration. lt is an ordinary text file. Enter'TYPE ERRORS.TRC' while

in the

conect directory

to

view the

file.

Detailed instruction for printing the errors is listed below.

lf a new calibration is started, the contents of ERRORS.TRC will be cleared and any new error messages will be written to the file. For 4-channel systems a history of all the failure is stored in the C:D(R26\CALTACE\ERRORS.HIS, and may be viewed at any

time.

After

a

problem

is

fixed,

Norland recommends deleting

this file.

To

delete

the file

type CDXR26\CALTRACE, press enter, type DEL ERRORS.HIS, and press

enter.

For 2-channel scanners the history of enors is not saved.

(11)

Printing

the

Errors.trc

Printing 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 the XSFT menu. Make sure your printer is on and ready. This will only print 3

pages

of the

erors.

Normally

the

first

few

enors

will be the

only information that is needed.

?

The DOS type command may also be used to print the entire enors.trc file.

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 Errors

This

erorwill

only happen on an initial calibnation. The77 step wedge is measured four times during the initial calibration. lf the count rate is different from pass to pass it will display this error.

Pass to Pass Error Example

Excessive variation from pass I to pass 2.

Filter=O, Metal=3, Plastic=7, Detector=l

Actual 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 detectors

are 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 +L3.66yo

Allowable

range

=

234397

-

251373 129515

-

139368

1.

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

2.

Perform a stability test with the source cooled to room temperature

_-

the source may be drifting or arcing, replace the source.

3.

Perform

a

table test

_-

count rate differences

at

different locations

will

cause the calibration 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 there is a gain drift.

(12)

6.

Perform

a

skiptest

-

missing steps could cause the x-ray beam to be in the wrong location 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 calibration standard or do not shut off the scanner. Terminate the current calibration. Re-enter

the

Host Software. DO NOT find Table Origin. DO NOT shut off the scanner. DO

NOT initialize

the

system. Restart

the

calibration. Verify

the

laser

is

automatically positioned over points

A

and B on the

calibration standard.

lf

not,

the

scanner is skipping steps. Note which axis is affected before proceeding.

Timeout Waiting

for

Counts

This 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 Correction

Actual 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 General Troubleshooting Guide for details.

Residual

Errors

This error can occur during a daily or an initial calibration. Basically it means the measurements of the steps do not fit the polynomial equation. Verify the calibration standard is not damaged, it is in the proper position, and sitting level on the table. Check the PMT spectrum to verify the PMT's are good, refer to the Calibration Examples

Appendix of this Calibration Troubleshooting Guide procedure. Perform a skiptest, stability test, Íilter test, and table test. Veri[t the background counts for 4-channel scanners are less than 12.

Correction

Factors

or

Drift Errors

During a daily calibration there are many comparison checks.

The correction factor is dividing the current calibration values by the running average of past calibrations or the initial. lf the values are perfectly matched then the conection value is one. lf the difference is too great that means the count rate difference between the cunent calibration and the running average is too great.

Drift errors are comparing the current calibration to the initial calibration. The following is an 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), by selecting Xdrift from page 2 of the XSST menu, rev 1 .3.1 or higher (2-channel enter SERVICE, the type XDRIFT). When prompted press any key to display the graph. After the graph is displayed press P to print.

(13)

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

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

2. lf

the

conection factors

or

drift

is

not

severe

a

new initial calibration may

fix

the

problem.

However

the

system should

be

monitored

to

verify

the

failure does not

occur in the near future.

3.

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

Limits

Encountered During Calibration

During an initial calibration the system measures the

tabletop.

The scanner arm may come in contact with one of the limit switches during an initial calibration. lf an enor dump occurs (blue screen background) press enter to print the

enor.

lf the screen has been by bypassed the enors are stored in the C:\XR26\ERRORS.LOG

Íile.

To print the contents

of

this file

enter

'CD\)(R26"

to

óange

to

the

XR26

directory,

then

enter

'TYPE

ERRORS.LOG >PRN'and press enter.

1.

ALWAYS FIND TABLE ORIGIN

AND

FIND TABLE DIMENSIONS, BEFORE AN INITIAL 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

Main Cable is not restricting arm travel.

4.

Veriff the arm moves freely on the rails. Any excess friction can cause the scanner to miss steps and encounter a limit switch. lt may be necessary to oil the

rails.

Do not use any lubrication with a degreaser such as

WD40.

Use light machine oil such as 3

in 1.

Communication

Error Displayed During Calibration

1.

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 locate its origin, and then continues on with the calibration from the point where it received errors.

2. lf

the

RETRY option fails,

tum

off

the

scanner power,

tum

it

back

on,

and select RETRY again to continue.

WARNING!!

DO

NOT SHUT

OFF THE

COMPUTER

_-

ONLY

TURN OFF

THE SCANNER.

3. lf

the

system still does not respond, tum

the

computer and scanner off.

Tum

the power back on and restart the calibration process. lf errors continue to occur, refer to the No Communication section of the GeneralTroubleshooting Guide.

(14)

QC

SPINE PHANTOM MEASUREMENTS

NOT WITHIN

SPECIFICATION

For

host software

2.3 or

later

a

measurement

of

the

Quality Control Phantom (QC Phantom) is part of the Daily Calibration routine. The precision and accuracy results of

this scan(s) are displayed graphically on the QA

screen.

Refer to the Operato/s Guide

for detailed information about the precision and accuracy wamings. lndividual QC scan

results

are

stored

in

the file

C:XR26\QC.FIL,

or

for

software versions 3.9.5

or

later C:XR26\NRLD_QC.FlL.

Also displayed is the numerical information regarding the BMC and BMD (optionalfat and lean) 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 values enterXD_QC

_-T.

2.

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

3.

Verify the conect information has been entered into the service setup screen of the host software. The calculations for precision and accuracy are based on these entered 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 the proper order.

6.

Verify the last 16 scans are valid. The calculations are based on the last 16 scans.

lf

some of those measurements are significantly different then the precision and accuracy for the last scan will be affected. Delete all bad values or start a new QC

file.

To rename the existing file enter CD XR26 to change to the XR26 directory, for

host software revision <3.9.5 enter REN QC.FIL QCMMDD.FIL (where mmdd is the month and day), and for host software revision 3.9.5 or later enter REN

NRLD_QC.FIL NRLDMMDD.FIL (where mmdd is the month and day).

7.

Perform a skiptest to verify proper arm movement.

(15)

r

l-I

l-

t-

l-Calib ration Troubleshooting Guide

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'

It[ trlià*rtior,:ll€trÈig

tá'86

Jtue 9?

IflIIIAL Cil-lgflfirl(ll

(

0 U It r

I

n T E 0iscrininatrr, Background &ference Derr llr:r. Of

f

*fl'?:1,iff:"

PASS P*55 p*s5 ?r55 ?à5S +455 ?{55 Shutter 'tr{"**m,'fitter 1{dilirn Íttra;'FiJter llish {tten, Filter

&nanir Filtrarim

talibrrtion'Statusi lll ?ROÊRSS

-

Scrnnisg {alibntiea Standad

-'l*rne _fuaining_{This ?hrse:}

_!t!]l

iiiit

iline

Xeiairdr$

S:ilÍtl9

i

prtss (Erc) to TPminat! -(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

FH'FL,lll'lL

--0iscririnator'ltÉ,22r:1?14'177

E;;[;;;ile

.s,s.s,z

f,eference

Bean

PAIS

$;i'ófí

_--

Pàss

36uíter

.pA55

iïi-Àiien,

rilter

PA5t

fràáiiin-ÀiieÀ.-ruter

PAss

iiiq["iÍtiÀÀ."Fitier

?i5t

iiyiiríÀ-ilitiliion

Ptss

- Scrnning (alihration Standerd -Iire Renaining This Phare: Q:Qí:89

ioïil

iín RefuÍning:

B:81:tl9

Prrss (Esc) to Ttrdnate [rlibration

fGncerl

(16)

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

anow

llt [rlibrrtion 0erslor

t.l.t

8! lloueÈer 9ó

PR55 tA55 Pe55 PA55 Pes9 PA55 PnsS ftIibrrtion Status:

-

telibrrtion Cop&tr

-Tin Renaining ThÍs Fhase: 8:8:80

ïotal

lim

Reirainins:

0:@:@ Prtss (EsÉ to frrïinàte (alibrltiott lTi'tÊin Referenca Bean trry Off Shutter

l-os Atten. Filter f{Bdiun f,ttÊn, FiltFr

Hish Atteo, Filter

Oynrnic FiltntÍott

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

es.àts*.d : ll Jut t9t Dat: !, tun t./lt,

eo{utF5d ! at Jut tgr !.t: l, ChD t/ltr

Àtrqa'Ern i ?ca* a..Tl ibc9eá i i : i q/bi <!m k taiiràt Fó* !/fl Llt\ 7/lL 3H6 t ààt ??a tór6 t?a

(17)

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

in.ly-.4 : ll lg tgl lrir t. chrn './ÍL l.stFa 3 lt a{ llt a.a! t. Gà.i l/tl-

_È*

t/Ítl lric ll?a l^! raíl B lntiill trÈ l,/FL l/lt Í.tL laSr lgrt a(.a l{at t?t c i t I lirat l]nla | 146 .t ?al lrla

(18)

I I

t-t^

t^

L 1

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.oucan 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 <4064 s/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'

(19)

a

I I l-I

l-XDRIFT EMMPLE 3

|ftherearespikesintheCALDRIFTgraphthismaybeduetothethermalinstabi|ityofthe

source

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.

(20)

XDRIFT

EXAMPLE

64138r'1997 15:53 414-563-S6Zt;

XR Xray Sourcc Drlft Plot Serl,rl lt

I .200 '-'Xlgh """Lw r .150 't _a.ra. 'ír'l'

_*..

r \\tr, 'ír PA'GE 61 Csrr.nÈ drtcrTue Lpr 29 L7.17.50 1997 i --l

'-i1rv..l---

/\

\'

|{

'lAv

_{v-^','--\tlï}

_t

'i*,-r-n

_'r\r..ur

_{,[[ ll}

_I

"'-'--".;r.,ll,i

t--{rH\-A\${t

l. roo l--I I I I I r.oso I ol OI 9l PI ol

Àl

ol oi

E

r.ooo

i.-;

È.4À4r dl ol 6l I o.rso i*-j I I 0.900 l.-. v \t\, ír!,...,_{. i í!.. .r} *'tttt' I 0.s50 l-. I I I { i ! I o.8oo f-t-.." o o Deya Síncr kÉtl,rl Crllbrctlon

(21)

XDRIFT

EXAMPLE

2

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

XR Xrey Sourcc Dríft ?lot Sorirl J:

PAGE A2

Cuttent deterTuo Apr 29 ló:36144 L997 I .100 1.090 1.o80 I .070 l.060 I .050 I .040 1.o30 1.020 l.oto t .000 0 .990 0.980 0.970 o.960 0.950 0.940 0.930 o.920 0.9t0 0.900 :

tl

_--ï

Htgh Le a ó D o À cl o c n D c ó

Deya SLncc lnltl-el c.lÍbÍrtl.on

Page 21

ii

.ivr

. '''

'i"1

a

(22)

XDRIFT

EXAMPLE

3

g4l38lLgs7 _L5t53 414-563-962ti

Sarir1 l:

FA6E 63

Currrnt drt.rTuc Apt 29 L7t24zO3 l99t

'-- Etsb -'- Lot q t ! t ! J á D t ! ! _t.. a o

lt

*!--_---J-o9 óo

D.t! Si.nc. Inltkl C.llbrstl.on

(23)

{F ;..i .f .s :Ji íiJ it s

XDRIFT

EXAMPLE

4

rr+f s{v,rt'iià l^tvs.!.d _Jtivt _8+{1.{,Í_Í:t}íi _d+s*+.'*.r,_{il*Í.**Íí,re}_À+r:_fÊ_srir:íJl}}*_g+íJi;

i ... .yÀ.i : i t:ri :..,, J.,1+l]. ,i ' {r.,$írír i I rl,ti:i{i i ii..::tjJS i' (..

ird:{ * $i.ll.ià .trjl.i:: r:.s:I. {14 l. í }gr..r.I Í.(rr

Page 23

(24)

AUTOSET.TRC EXAMPLE

PRINTOUT

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