• Topic ID: id_16158059
  • Version: 2.0
  • Date: Nov 7, 2019 8:53:56 PM

X-Ray Tube Replacement

Prerequisites

Overview

Figure 1. Tube Removal Diagram

1 Data Entry

note:

The following procedure is required prior to the actual tube replacement. If you perform the data entry after tube replacement, the system will set the tube heat data to the maximum, and you will have to wait for a pretty long time until the tube heat data lowers.

Procedure

  1. Open SERVICE DESKTOP.
  2. Enter the data of the new tube:
    1. Select REPLACEMENT.
      note:

      Perform Tube Installation Certification, if required. Refer to SmarTube™ Setup.

    2. Select TUBE CHANGE.
    3. Select NEWTUBE CONFIG, select a proper Tube Unit Failure Code (reason for tube replacement), Insert Serial #, and Housing Serial # of a new tube, then click on OK.

      Figure 2. Change Tube Information Screen

2 Old Tube Removal

Procedure

  1. (For European mobile units manufactured by Medical Coaches, Inc., also known as Medcoach vans) Prepare the scan room and follow the instructions in Prepare Mobile Scan Room for Component Replacement.
    note:

    Space around the Gantry in a mobile van is very limited. Use caution when lifting and moving the Tube into and out of the scan room.

    • danger
    • Electrocution hazard
    • High Voltages present.
    • Use proper lockout/tagout procedures before replacing components. See safety menu of Service Document gui for appropriate procedures.
    • danger
    • CRUSH HAZARD.
    • UNEXPECTED GANTRY ROTATION CAN CAUSE SERIOUS INJURY.
    • Use the gantry rotation lock to lock out gantry rotation. See safety menu of Service Document gui for appropriate procedures.
  2. Remove and set aside gantry side, top and front covers.
  3. Remove the M10 screws holding support bracket for the right front gantry cover and set the assembly aside. (For CT System Only) It may be necessary to tilt the gantry back to remove the third bolt if present which is not normally installed on some systems.

    (For PET Systems Only with the BrightSpeed Gantry) There may or may not be a lower screw present. If the lower screw is present it must be permanently loosened and left loose using the short stubby 8 mm hex wrench provided with FMI 13693. The wrench is located in the Service Cabinet on site. If necessary this wrench (P/N 5367896) can also be ordered and should be left on site.

    Figure 3. Right Front Gantry Cover Support Bracket

    4. Notice Image
    • notice
    • (For CT System Only) If the gantry must be tilted, remember to tilt the gantry back to zero degrees.
  4. Turn off the AXIAL DRIVE ENABLE, HVDC ENABLE, and 120VAC switches.
  5. Turn off facility power to PDU and lockout/tagout according to lockout/tagout procedure.
  6. Rotate the Gantry until the x-ray tube reaches the 3 o’clock position.
    note:

    It may be easier to loosen the M12 tube mounting bolts with the tube at about the 2 o’clock position before locking the tube at the 3 o’clock position. Simply loosen the tube mounting bolts one half (1/2) turn. Do not remove the bolts yet.

    Figure 4. Tube Angle to Loosen and Torque M12 Screws

    • warning
    • Crush Point.
    • If the gantry is not securely locked, upon removal of the X-Ray tube, the gantry will violently rotate due to weight imbalance.
    • Ensure the gantry is securely locked by attempting to rotate the gantry by hand.
    Notice Image
    • notice
    • Make sure the tube is at 90 degrees so the tube hangs at the correct engagement angle for removal and installation.
  7. Engage gantry rotational lock, and check that the gantry is securely locked by attempting to rotate the gantry by hand.
    8. Notice Image
    • warning
    • severe injury possible.
    • if the hoist hook's lock nut is loose, then the x-ray tube might drop from the hoist, with the resulting in serious injury to service personnel.
    • before using the hoist, check to make certain that the hook's lock nut is not loose. If it is loose, do not use the hoist. instead, order a new hoist.
  8. Insert the lifting post, boom and chain hoist. Reference Figure 3.
  9. Disconnect the 12 pin tube I.D. system cable, from the top of the tube unit.
  10. Disconnect the 4 pin mate-n-lock pump and fan power system cable.
  11. Disconnect the ground strap from the top of the tube unit.
  12. Remove the anode and the cathode cable:

    • Carefully cut tie-wraps securing HV cables. Note HV cable routing.

    • Loosen each cable’s locking ring with the spanner wrench.

    • Pull each cable terminal out of its receptacle.

    • Ground the end of the cables to the Gantry frame.

    • Wipe up any oil that drips from the cable terminal.

    • Use paper towels to soak up any oil in the wells.

    • caution
    • Crush Hazard.
    • Remove the mounting bars in the following (lower/upper) order to lessen the risk of injury to your hand. Keep one hand under the bolt and pressure plate while unfastening it. This is to prevent them from falling into the fan that is attached to the tube.
    note:

    It may be easier to tape the socket to the extension. This will prevent the socket from being dislodged on the tube radiator assembly

  13. The XRT is attached to the Collimator with a Tube Mount Bracket Assembly. Remove the mounting plate & XRT from the Collimator by removing the four M12 cap screws and lock washers, and two load plates, with a hex socket driver. With your hand, reach behind the radiator to the screws from either side of the XRT center section while removing the bolts with two 12-inch extensions (24 inch length) on a ratchet. Throw these M12 bolts and washers away, as they should not be reused.
  14. Carefully swing the tube clear of the gantry.
    note:

    Be careful not to damage the fragile copper filter or lead shield in the mounting plate for the next step.

    15. Notice Image
    • warning
    • Severe Injury Possible.
    • Tube can separate from gantry.
    • DO NOT REMOVE FACTORY INSTALLED MOUNTING PLATE.
  15. If the replacement tube has a mounting plate attached (see Figure 5), DO NOT REMOVE IT. SkipStep 16 and Step 17.

    Figure 5. Tube Shipped with Mounting Plate Attached

    16. Notice Image
    • notice
    • Potential for IQ Artifacts. When removing the mounting plate from the tube, be careful with the Copper Filter. It should be free of debris, scratches and dust. Particles create artifacts in the image by affecting the attenuation properties of the copper filter.
  16. If the replacement tube does NOT have a mounting plate attached, remove the mounting plate by removing the four M10 (P/N 46-328416P20) hex head screws. Throw these bolts and washers away, as they should not be reused.
  17. If new tube has no mounting plate attached, inspect the copper filter. The copper filter should be clean, dent and scratch free:

    Figure 6. Extremely Contaminated Copper Filter

    note:

    Perform the following inspection before installing the new tube unit. Also look at the tube side of the copper filter when you are swapping the interposer plate.

    The following tools are required for this inspection procedure:

    • Phillips #2 Screwdriver

    • Flat blade Screwdriver

    • Bright Flashlight

  18. Inspect the Bowtie Filter. It is possible that the Bowtie Filter is contaminated and the Primary Copper Filter is not contaminated.
    1. Remove the Collimator Control Board Sheet Metal Cover. See Figure 7.

      Figure 7. Collimator Control Board Cover

      • warning
      • Potential for shock.
      • Voltage is present.
      • Do not attempt to move the filter with power on.
      Notice Image
      • notice
      • Do not force the filter if it feels stuck. Damage to the limit switch can result. Do not move the filter more than necessary for inspection. The filter can fall off the drive screw.
    2. With power removed from the gantry, use a flat blade screwdriver and position the bowtie filter assembly so it is visible through the input port or tube side of the collimator assembly.

      • CCW will move the filter into the beam. See Figure 8.

      • Do not move the filter back to the home position.

      Figure 8. Filter Position Adjuster

    3. Using a flashlight, inspect the bowtie filter for contamination. Reference Figure 9.

      Look through the input port or tube side of the collimator.

      If contamination is visible, proceed to Collimator Cleaning Procedure.

      Figure 9. Contaminated Bowtie Filter

  19. Verify that the Lexan plastic has been removed from the collimator. If it is still there, remove it following the procedures in Lexan Removal .

3 New Tube Installation

Procedure

    • danger
    • CRUSH HAZARD.
    • UNEXPECTED GANTRY ROTATION CAN CAUSE SERIOUS INJURY.
    • Never service the gantry with the axial drive enabled. Use the gantry rotation lock to lock out gantry rotation. See safety menu of Service Document gui for appropriate procedures.
    • danger
    • Electrocution hazard.
    • High Voltages present.
    • Use proper lockout/tagout procedures before replacing components. See safety menu of Service Document gui for appropriate procedures.
    • warning
    • Severe Injury Possible.
    • Tube can separate from gantry, if not torqued correctly.
    • Always use proper torque on all fasteners.
  1. Allow the tube unit to warm to room temperature before you install it.
    2. Notice Image
    • warning
    • Severe Injury Possible.
    • Tube can separate from gantry.
    • Do not remove factory installed mounting plate.
  2. If the new tube has a factory installed mounting plate, DO NOT REMOVE IT. Skip to Step 4.
    • warning
    • Severe Injury Possible.
    • If you turn the torque wrench more than 90º (1/4 turn) while applying final torque, the mounting threads are stripped.
    • Do not use this tube.
  3. Attach the mounting plate from the old tube using new M10 x 25mm bolts provided with the tube. Do NOT use Loctite.

    • Finger tighten all four (4) bolts

    • Torque all four (4) bolts to the following specification:

    This seats each bolt, enabling you to visually ensure that the mounting holes are not stripped while applying final torque.

    Apply final torque on all four bolts:

    Figure 10. Tube and Mounting Plate

    4. Notice Image
    • notice
    • Potential for IQ artifacts. When attaching the mounting plate on the tube, be careful with the Copper Filter. It should be free of debris, scratches and dust. Particles create artifacts in the image. Use a lint free wipe to clean, if needed.
  4. Re-check facility power and make sure it is off.
    • warning
    • Severe injury to patient could occur.
    • Using the wrong bolts could place stress on bolts, causing tube to separate from gantry.
    • Use proper bolts.
  5. Use the hoist to lift the new tube unit:
    1. Position the tube on the gantry: The “crosses” on the mounting plate and on the collimator should fit in perfectly when the tube is aligned properly.
      note:

      • To ease installation, fasten the top pressure plate to the rotating structure first. Then attach the bottom pressure plate.

      • Use new bolts and washers from tube crate. Make sure to select the proper bolts. There are instructions in the crate, and on the tube itself.

    2. Fasten the lower and upper and pressure plates to the rotating structure with the four M12 (50 mm) bolts, and set pre-load torque to:
    3. Set final torque to:

      Figure 11. Tube and Mounting Plate

  6. Attach the tube I.D. cable to the 12 pin mate-N-Lock connector on top of the tube.
  7. Attach the tube pump and fan power cable to the 4 pin mate-N-Lock connector.
  8. Fasten the grounding strap to the 1/4-20 ground stud on top of the tube unit.
  9. Remove the plastic cap plug from each cable receptacle on the tube unit.
    note:

    Take care not to lose the rubber quad rings for the High Voltage cables.

  10. Lightly wet the new rubber quad ring with transformer oil (917).
  11. Return the quad ring to its slot at the top of the receptacle retaining ring.
  12. Pour transformer oil (917) into the receptacle to a depth of 10 mm (0.375 in).
    13. Notice Image
    • notice
    • Incorrectly routed or secured HV cables will result in damage to the HV cables and/or other parts of the gantry.
  13. Be sure to route the HV cable as shown in Figure 12.

    Figure 12. HV Cables Properly Routed and Secured

  14. Align the cable terminal orienting key with the notch in the receptacle.
    15. Notice Image
    • notice
    • Do not over tighten the locking ring. Over tightening can deform the cable plug sealing surfaces, break the oil seal between receptacle and housing, twist the receptacle, and disrupt internal wiring.
  15. Slowly insert the cable, to engage the connector pins, and seat the cable in the well.

    • Tighten the cable locking ring.

    • Rotate the cable strain relief for a clean cable dress.

    16. Notice Image
    • notice
    • IF YOU GET OIL ON YOUR HANDS, WASH THEM NOW.
  16. Carefully wipe up all excess oil.
  17. Secure HV Cables using large tie-wraps, as shown in Figure 12.
  18. Disconnect hoist from tube and boom.
  19. Remove the post and boom from the gantry. Reference Figure 3.
  20. Check for oil leaks:

    • Wrap rags or paper towels around the cable horns, and tape them into place.

    • Manually rotate the tube to the 6 o’clock position.

    • Return the tube to the 3 o’clock position

    • Remove the toweling and wipe up all excess oil.

    • Wipe off the cable horns, locking rings and strain reliefs with an alcohol-dampened rag.

    • Repeat with a dry rag.

    • Wrap the cable strain reliefs and locking rings with a single layer of absorbent paper tissue. You can use two inch wide strips cut from a paper napkin.

    • Wrap the bottom edge of the paper around the top end of the cable horn, and tape it in place.

    • Extend the top edge of the paper over the top of the locking ring, and tape it to the plastic cable strain relief.

    • Remove paper after leak check.

  21. If oils leaks are found, tighten the locking ring slowly until there is no leakage, paying attention to not over tighten.
  22. Install the right gantry front cover bracket. Reference Figure 3.
    note:

    For PET systems only reinstall the top M10 screw. If the lower screw is present on a PET system do not tighten it. leave the lower screw loose.

  23. Restore system power at the main disconnect panel.
  24. Turn on gantry 120 VAC, HVDC ENABLE and AXIAL DRIVE ENABLE on the service switch panel. Wait at least 10 minutes to warm up the filament.
  25. Reset the system:
    1. Open SERVICE DESKTOP.
    2. Select SYSTEMRESETS.
    3. Select SCAN, then RUN.
  26. Verify tube types match before proceeding:
    1. Select ERROR LOGS.
    2. Select TUBE USAGE.
    3. Select SUMMARY FOR.

4 Finalization

Procedure

  1. Checklist
    1. New mounting bolts and washers are used for mounting the tube; old mounting bolts and washers are discarded.
    2. Proper torque specifications are followed for all fasteners (see Torque Wrench Information).
    3. Tie-wraps and cables are in place.
  2. Perform Tube Installation Certification, Refer to SmarTube™ Setup.
  3. If you have a system with the detector and collimator previously aligned before this tube change and there are no image quality issues, use the “Quick Tube Change” procedure below in the order described.
    1. SmarTube™ Setup
    2. Gantry Rotation Safety Check
    3. Reset Tube TnT Data (Generator Tool)
    4. Tube Z-Align
    5. ISO Alignment Procedure
    6. Meter Verification (LS16, Ultra & Plus)
    7. HV Tank Feedback Resistor Verification
    8. Filament Calibration
    9. HHS Scans

      Tube Usage Information is found on the Common Service Desktop following path:

      Error Logs>Tube Usage>Details.

    10. Gantry Balance Procedure
    11. Hot ISO Alignment
    12. Z-Slope
    13. DAS Gain Calibration
    14. Collimator Calibration
    15. Detailed Cals
    16. N Number Check
    17. System Scanning Test
    18. Quality Assurance Test
    19. New Tube Configure
    20. Save System State
  4. If you cannot follow the quick tube change procedure for any reason, perform the retest steps below in the order described.
    1. Install TubeInstallFlex option through eLicense, as needed. Refer to Tube Identification (Tube Alignment Workflow)
    2. Gantry Rotation Safety Check
    3. Reset Tube TnT Data (Generator Tool)
    4. Plane of Rotation (POR) Alignment
    5. Beam on Window (BOW) Alignment
    6. CBF/SAG Alignment Process
    7. ISO Alignment Procedure
    8. Meter Verification (LS16, Ultra & Plus)
    9. HV Tank Feedback Resistor Verification
    10. Filament Calibration
    11. HHS Scans

      Tube Usage Information is found on the Common Service Desktop following path:

      Error Logs>Tube Usage>Details.

    12. Gantry Balance Procedure
    13. Hot ISO Alignment
    14. Z-Slope
    15. DAS Gain Calibration
    16. Collimator Calibration
    17. Detailed Cals
    18. N Number Check
    19. System Scanning Test
    20. Quality Assurance Test
    21. New Tube Configure
    22. Save System State