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What This Guide Helps With
Identifies external causes of gantry motion or positioning faults, including obstructions, interlocks, control issues, or system readiness conditions preventing movement.
Step-by-Step Troubleshooting
Ensure Patient Safety First
- Confirm no patient is positioned in the unit and the gantry is not in compression.
- If a patient is present, safely remove them and move to another unit.
- Why: Prevents injury from unintended gantry movement.
Observe Error Message and Motion Behavior
- Attempt a small gantry movement and note:
- No movement at all
- Stops immediately
- Moves intermittently or inaccurately
- Expected Outcome:
- No movement → likely interlock or control issue
- Partial/intermittent movement → possible obstruction or encoder issue
- Why: Helps determine whether the issue is mechanical, electrical, or control-related.
Check Emergency Stop (E-Stop) Buttons
- Inspect all E-stop buttons (gantry, room, operator console). Ensure they are fully released.
- Expected Outcome: Releasing an engaged E-stop restores gantry motion.
- Why: E-stops disable all motion functions for safety.
Verify Compression Paddle Status
- Ensure the compression paddle is:
- Fully released
- Properly seated
- Not obstructing gantry travel
- Expected Outcome: Proper paddle positioning allows normal gantry movement.
- Why: Paddle position can trigger motion interlocks.
Inspect for Physical Obstructions
- Check around and behind the gantry for:
- Cables or cords
- Step stools or positioning aids
- Wall or detector clearance issues
- Remove any obstruction.
- Expected Outcome: Clearing obstructions restores normal movement.
- Why: Mechanical resistance can trigger safety stops or positioning faults.
Verify System Ready / Exam State
- Check the system interface for readiness status. Ensure:
- No active exam is locking motion
- No system warnings preventing movement
- Expected Outcome: System shows ready or idle state with motion enabled.
- Why: Certain states prevent gantry movement for safety or workflow control.
Test Gantry Controls (All Input Methods)
- Test gantry movement using:
- Control panel
- Footswitch (if applicable)
- Hand controls
- Expected Outcome: Movement should respond consistently across all controls.
- Why: Helps identify if the issue is input/control-related rather than mechanical.
Perform a Controlled System Restart
- Shut down the system using proper procedure. Wait 2–3 minutes, then power back on.
- Expected Outcome: Temporary faults or positioning sync errors may clear after reboot.
- Why: Motion systems rely on proper initialization and position referencing.
Listen for Unusual Sounds During Movement Attempt
- Attempt movement and listen for:
- Clicking or grinding
- Motor engagement without motion
- No sound at all
- Expected Outcome:
- Motor sound with no movement → possible mechanical binding
- No sound → possible interlock or control issue
- Why: Provides clues about motor vs control failure.
If the Problem Persists
If all external causes have been ruled out, the issue is likely internal (motor drive, encoder, or control system fault).
Remove the device from service, label it Out of Service, and send for repair or further bench evaluation.
Knowing when to stop prevents unnecessary risk and protects system components.
Clinical Use Tip
Never troubleshoot gantry motion with a patient in position. Always move the patient to another unit before attempting movement-related troubleshooting.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Gantry would not move; positioning error displayed during exam setup."
Cause
What was observed during troubleshooting.
Example:
"No external obstruction found; E-stop released; system restart did not restore motion, indicating likely internal gantry drive issue."
Resolution
What action was taken.
Example:
"Removed unit from service, labeled Out of Service, and escalated for vendor repair."
Helpful Details to Include (If Known)
- E-stop status verified
- Paddle position confirmed
- Obstructions checked and cleared
- Control inputs tested (panel/footswitch)
- System reboot performed
- Error messages recorded
- Any abnormal sounds noted
- Final device status (removed from service)
Final Thought
Gantry motion issues should always be approached from a safety-first, external-check perspective. Most faults are related to interlocks, obstructions, or system state. When those are ruled out, escalation is the correct and professional decision. Proper documentation ensures clarity and continuity of care.
That is successful troubleshooting.