Quality Assurance

Calibration Procedures

Calibration procedures should be performed for quality assurance and in order to evaluate the performance of the MEG system.

CALIBRATION PROCEDURE:	PERFORM WHENEVER:
MEG Noise Collection	There is line frequency noise
Head Coil Calibration	Head localization results / accuracy is in doubt
EEG Gain Calibration	EEG results are uncertain
Magnetic Phantom Measurement	The performance of the MEG system is in question

MEG Noise Collection

Noise collection calibration procedures will be performed for quality assurance whenever necessary to evaluate the performance of the MEG system. Noise collection is performed to determine the noise level of each individual channel. Data is collected with no subject and all noise sources are removed from the immediate vicinity of the MEG system.

1. Procedure for acquiring data:

a. Make sure that the Magnetic Phantom is not connected / setup performing a noise collection.

b. Close the door to the MSR.

c. Click” Acq Manager” (or click on the Terminal Screen and type “Acq” at the prompt line; then go to step# h.)

d. Click on “Select User”.

e. Select “meglab”.

f. Click on “Launch Acq”.

g. Select the study type: “Noise”.

h. Click on “Ok”.

i. In the Acq Window, click on “Acquire data”.

j. Create Directory? Select “Ok”. (If this is the first recording of the day you will need to create a directory)

k. At the Acquisition Monitor Window adjust the scale.

l. Click on Start. There are 10 -10 sec trials.

m. When the collection is done click “Ok” at the “General Information Window”.

n. Enter noise collection scan in the logbook.

2. Procedure for Viewing/Plotting the Data:

a. At the "General Information Window" click on "Tools".

b. Click on DataEditor.

c. Click on Set.

d. Select “MEG Left+ZF ZO” channel array.

e. Click on the Frequency Spectrum Display icon.

f. Click Display

g. Click Trial; Stack all trials

h. Change y axis to “5f to 10f”. Hit Enter.

i. List channels that have increased power on the Daily Log.

k. Repeat for the "MEG Right+ZC ZP” channel array.

k. List channels that have increased power on log.

Head Coil Calibration

1. Head Coil Calibration will be performed for quality assurance as part of the maintenance and calibration procedures whenever

a. Necessary to evaluate the performance of the head coil

b. A head coil is replaced or to evaluate the performance of the MEG system.

2. About Two Point Calibration Head Coil Calibration using the Magnetic Phantom:

a. Each coil is placed in two positions on the lower calibration ring of the Magnetic Phantom.

b. Two recordings are collected with the 3 or 4 head coils positioned on the calibration ring to determine the magnetic dipole moments of the head localization coils.

*Disassemble the Magnetic Phantom before performing any noise collection.

3.Head Coil Setup:

a. Fasten the Head Coils to the calibration points located on the outside surface of the Dewar using the white plastic screws. Plug the other ends into MEG jack box. Head coils are placed as usual with:

i. The red coil affixed to the right calibration point (if facing the dewar; your left),

ii. The green coil attached to the left side,

iii. The blue in the mid front and

iv. The yellow (spare) mid back.

4. Calibration Program:

a. Open a Terminal window.

b. Type: su meg (lowercase).

c. Enter password: “omega2000”.

d. Enter: “calibrateCoils”.

5. Calibration Procedures:

a. Type “calibrateCoils” at a command line prompt
(or click on the calibrateCoils icon on the desktop).

b. Verify the head localization parameter file.

c. Hit ENTER if correct. (MO15_1609.hz.rp)

d. Hit ENTER to backup the current head localization parameter (rp) file and verify serial numbers.

e. Do you want to calibrate the ADC? Enter: “YES”.

f. DSQ Electronics Setup menu displays.

g. Calibrate the ADC units used to apply signals to the head localization coils.

h. Click on Channel Selector - right arrow. Start @ ADC 15. (calibrate each ADC individually; there are 16 ADC’s)

j. Click on Start Collection.

k. Click on File and Exit

m. Do you want to enter coil frequencies manually? Enter Y for yes.

n. To accept frequency values for coils hit ENTER.

6. Starting Data Collection #1

a. Hit ENTER to launch Acq to start Data Collection #1.

b. Hit ENTER to select turn reference channels off.

c. Once Acq has started click on Acquire Data.

d. At the Question Menu click Yes.

e. Click OK for the folder name if asked.

f. Decrease scale.

g. When data starts scrolling across the screen, click on the Start button.

h. When the window appears indicating that trial #1 has been collected, click the OK button.

i. Select Close Window menu item from the File Menu.

j. Select Exit from the File Menu.

k. When Acq exits, hit the ENTER <Y> key to verify the data set collected.

7. Starting Data Collection #2

a. Swap the head coils for the second data collection:

i. Swap the left (green) with the right (red) head coil;

ii. Swap the front (blue) with the back (yellow) head coil.

b. Hit ENTER to launch Acq for Data Collection #2.

c. Hit ENTER to select turn reference channels off.

d. Once Acq has started click on Acquire Data.

e. At the Question Menu click “Yes”.

f. Decrease scale.

g. When the window appears indicating that trial #2 has been collected, click the OK button.

h. Select Close Window menu item from the File Menu.

i. Select Exit from the File Menu.

j. When Acq exits, hit the ENTER <Y> key to verify the data set collected.

k. The distance between configurations #1 and #2 for each coil will be calculated and displayed. Hit ENTER to accept the distance.

Note: The distance should be 51.49 cm for the Omega-275 System.

l. The moments will be calculated for each coil and displayed. Hit ENTER to accept these values.

Note: a typical coil moment is 1.7e+11 to 1.8e+11 (fT*cm3)/A. Our range is: 1.6e+11 to 1.8e+11.

m. Hit RETURN to launch Acq (writes values into the parameter (rp) file).

n. At the Question “Do you want to use these values/”, click “Yes” or hit the Enter key to accept the results.

o. At the prompt “Remove calibration results datasets” hit RETURN to remove.

Important!!! Please perform a phantom dipole test to verify the new calibration moments!

EEG Gain Calibration

EEG Calibration procedures will be performed for quality assurance whenever necessary to evaluate the performance of the MEG / EEG system and / or if EEG results are in doubt.

*Disassemble the Magnetic Phantom before performing gain calibration.

1. Touch the gold static button before removing the head box and before inserting the shorting plug.

2. If applicable, remove the EEG jack box.

3. Mount the green EEG Gain Calibration Card (also called the Shorting Plug) on the amplifier.

4. Run Acq for EEG calibration.

a. Select - Calibrate.

b. Select - EEG.calib

5. At the query “Would you like to save the protocol as the default for the study?” enter NO.

6. Click on the WINDOWS menu.

7. EEG channel (highlight 64 EEG channels).

8. Select Null Offset.

9. Select Cal gain.

10. At Warning click OK.

11. Save.

12. Exit Acq; NO (do not save rp file).

13. Dsqsetup (To write values to the database).

14. File.

15. Save as: Type (“today’s date”. rack).

16. Click OK.

17. Select Exit.

18. Record Values in the database. Type “. /recordcaib.py –w” (write to database).

The gain corrections are typically 1.0 + 2%.

Magnetic Phantom Measurement

Magnetic Phantom procedures are performed for quality assurance whenever necessary to evaluate the performance of the MEG system. Magnetic Phantom Dipole Localization is used to confirm the localization accuracy of the system by energizing a coil at a level similar to that of a brain signal and calculating its position relative to a coordinate system determined by the head localization coils.

*Always disassemble the Magnetic Phantom before performing a noise collection.

1. Magnetic Phantom Setup:

a. Place the platform board on the MEG chair under the Dewar.

b. Position the Magnetic Phantom (the one with the flat white top) on platform. The energizing cable should be right of center and the Blue Head Coil center.

c. Connect the 3 head coils (Red –right; Green –left; Blue –center) to the magnetic phantom.

d. Plug the energizing cable from the phantom into the MEG jack box spare slot.

e. Raise chair so that the phantom is under the helmet.

f. Position all the cables so that they hang straight down and do not touch each other.

2. Running the Calibrate Program from the ACQ Computer:

a. Type “Acq”.

b. Select Study Type “Calibrate”.

c. Select Magnetic Phantom.

d. Might get an error message here. Select NO.

e. Acquire data.

f. Click on Localize Head.

g. OK to start localization.

h. Continue.

i. Start.

j. Click on Continue.

k. Click on OK.

l. Tools menu. Data Editor. Select a set of channels. Expand scale. Drag to pick (pick peak with bar). Display map to check (Select Topograph).

m. To perform calculation - Select Tools; Magnetic Dipole Fit; Display LaunchApp.

Report if fit error is > 2 - 2.5 mm.

n. Magnetic Dipole Fit

o. Position should be 0, 0, and 0 .05

p. File. Exit.

q. File. Close Window.

r. Exit Acq.

Problem Reporting and Process Improvement

The problem reporting system is intended to enhance safety, increase the quality of data collection, and improve user support.

Problem Reporting

1. The problem report form (under construction) is used to report, track, evaluate / assess, and manage: ::::a. Equipment malfunction and/or failure

b. Adverse events, near-misses, close calls, hazardous conditions, injuries and sentinel events

c. Departures from normal operations

d. Non-compliance with policies, procedures, and practices involving staff, users, subjects / patients and/or equipment.

2. The objective of the problem reporting process is to determine the factors contributing to the occurrence in order to implement practices and systems to prevent any recurrence.

3. A Problem Report can be initiated by users, subjects / patients and staff.

4. The Problem Report is not a substitute for reporting of events to other authorities, including the IRB, institute clinical director, PI, etc.

5. Problems/issues can be submitted anonymously

6. If unsure whether to report, err on the side of reporting

Quality Improvement / Suggestions

1. Users are encouraged to make suggestions and provide feedback to MEG staff, by directly contacting the staff scientist (Tom Holroyd) and director (Allison Nugent).

2. Anonymous suggestions for quality improvement can be made through the Problem Report Form (under construction)