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What This Guide Helps With
Troubleshooting gantry rotation, patient table movement, detector positioning, or acquisition setup faults before repair escalation.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Confirm whether a patient is on the table or positioned near the gantry.
If the fault occurs during patient setup or acquisition, stop movement immediately and have clinical staff safely remove or reposition the patient according to site policy.
Expected outcome: The patient is protected from unintended table, gantry, or detector movement.
Confirm the Exact Motion or Positioning Fault
Ask Nuclear Medicine staff what movement failed and when it occurred.
Determine whether the issue involves:
- Gantry rotation not starting
- Gantry rotation stopping mid-motion
- Patient table not moving
- Table movement stopping unexpectedly
- Detector head positioning issue
- Acquisition will not start because position is not accepted
- Collision, limit, or proximity warning
- Intermittent positioning fault during one protocol
Expected outcome: The fault is separated into gantry, table, detector, positioning, or acquisition setup.
Check for Physical Obstructions Around the System
Inspect the gantry, table path, detector travel area, floor area, and patient positioning accessories.
Look for stools, step platforms, cables, linens, immobilizers, phantoms, or other items blocking motion.
Expected outcome: No external object is preventing safe gantry, detector, or table movement.
If an obstruction is found and removal restores normal motion, document the cause and stop.
Verify the Patient Table Is Clear and Properly Loaded
Confirm the table is not overloaded, unevenly loaded, or restricted by patient accessories.
Check that pads, straps, arm boards, and positioning aids are not caught between moving sections.
Expected outcome: The table can move freely without mechanical restriction.
Check Emergency Stop and Motion Enable Conditions
Verify that no emergency stop button is engaged.
Confirm that any required motion enable controls, hand controls, foot controls, or operator controls are available and functioning normally.
Expected outcome: The system is not being held in a stopped or inhibited state by an external safety control.
Review the System Message or Error Prompt
Check the operator console, acquisition workstation, or gantry display for the exact fault message.
Note whether the system reports a limit, collision, table position, detector position, gantry position, interlock, or communication issue.
Expected outcome: The displayed fault helps identify whether the issue is safety-related, position-related, or control-related.
Check Table Docking, Alignment, and Travel Limits
Confirm the table is properly aligned with the gantry and has not reached a mechanical or software travel limit.
If the table is near an end stop or unusual position, have trained staff attempt normal return-to-home or repositioning through approved operator controls.
Expected outcome: The table position is valid and not preventing acquisition setup.
Check Gantry and Detector Position Before Acquisition
Verify that the gantry and detector heads are in a safe, expected starting position for the selected study.
Confirm that the selected protocol matches the required patient position, table orientation, and detector configuration.
Expected outcome: The system accepts the setup and allows acquisition positioning.
Confirm the Issue Is Not Protocol or Setup Related
Ask whether the fault occurs with one study type, one patient orientation, one acquisition protocol, or all movements.
If only one protocol fails, compare setup requirements with a known-good protocol or have Nuclear Medicine verify the acquisition setup.
Expected outcome: Incorrect protocol setup is ruled out before assuming hardware failure.
Check Hand Control, Operator Panel, and Console Inputs
Confirm whether movement fails from one control location or all control locations.
If motion works from the console but not from a hand control, the issue may be isolated to the accessory or control path.
Expected outcome: The issue is narrowed to system motion, user control input, or accessory control.
Inspect Visible Cables and Connectors Externally
Check visible table, gantry, detector, and control cables for loose connections, damage, strain, or signs of being pulled.
Do not open covers or disturb internal cabling unless approved by service procedure and site policy.
Expected outcome: No obvious external cable issue is causing intermittent motion or communication faults.
Power Cycle Only When Safe and Appropriate
If no patient is on the system and the department agrees, restart the acquisition workstation and system using the approved site process.
After restart, verify whether the gantry, table, and positioning functions return to normal standby status.
Expected outcome: Temporary software or communication lockup is cleared.
Perform a Controlled Functional Check
With no patient on the table, have qualified staff test basic table movement, gantry positioning, and acquisition setup movement within normal safe limits.
Observe for repeated stops, abnormal noises, jerky movement, position mismatch, or recurring error messages.
Expected outcome: Motion is smooth, controlled, and repeatable without alarms.
Do Not Continue Repeated Motion Attempts if Faults Recur
If the gantry, table, or detector repeatedly stops, alarms, moves unpredictably, or reports position mismatch, stop troubleshooting.
Continued attempts may create risk to patients, staff, or equipment.
Expected outcome: The device is not forced through a possible motion control or safety fault.
If the Problem Persists
If common external causes have been ruled out, the issue may involve an internal motion drive, encoder, limit sensor, collision detection circuit, table control circuit, gantry control system, or acquisition workstation communication fault.
The device should be:
- Removed from clinical use
- Labeled Out of Service
- Escalated for Siemens service, repair, or bench-level evaluation as appropriate
Knowing when to stop is proper troubleshooting. A Nuclear Medicine system with unreliable gantry, detector, or table movement should not be used for patient imaging until motion and positioning safety are verified.
Clinical Use Tip
Do not troubleshoot motion faults with a patient on the table unless the immediate goal is safe patient removal. Once the patient is clear, perform checks with the table unloaded and the gantry area clear.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Nuclear Medicine staff reported that the Symbia Evo gantry stopped during acquisition positioning and would not complete setup for the study."
Cause
What was observed during troubleshooting.
Example:
"External inspection found no obstruction, emergency stop, table accessory interference, or incorrect protocol setup; the gantry positioning fault repeated during unloaded functional testing."
Resolution
What action was taken.
Example:
"Removed the Symbia Evo from service, labeled it Out of Service, documented the recurring positioning fault, and escalated for service evaluation."
Helpful Details to Include (If Known)
- Whether a patient was on the table when the fault occurred
- Exact error message or system prompt
- Gantry position when the fault occurred
- Table position and movement direction
- Whether detector movement was involved
- Whether emergency stop was checked
- Whether obstruction or accessory interference was found
- Whether the issue affects one protocol or all protocols
- Whether motion works from one control but not another
- Any unusual noise, vibration, odor, heat, or jerky movement
- Final device status
Final Thought
Gantry, table, and acquisition positioning faults require careful, safety-first troubleshooting. Start with the environment, patient setup, controls, interlocks, and visible external conditions before suspecting internal motion components. If motion is unreliable or faults repeat, remove the system from service and document the complaint, cause, and resolution clearly.
That is successful troubleshooting.