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What This Guide Helps With
Troubleshooting patient table movement, travel limits, indexing, height, docking, or scan positioning errors using safe external checks first.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Confirm whether a patient is on the PET / CT table.
If table movement is unreliable, unexpected, blocked, or not responding normally, stop all table motion immediately.
Expected outcome: The patient, staff, IV lines, positioning aids, and accessories are protected from unintended movement or collision.
If patient safety is affected, remove the system from clinical use and escalate immediately.
Confirm the Exact Table Symptom
Ask the technologist what occurred and when it occurred.
Identify whether the issue involves:
- Table will not move
- Table stops before reaching the expected position
- Table limit message
- Table height issue
- Incorrect scan range
- Patient positioning mismatch
- Table indexing error
- Gantry/table collision warning
- Motion failure during PET, CT, or combined PET/CT acquisition
Expected outcome: The failure mode is clearly identified before troubleshooting continues.
Check for Obstructions Around the Table and Gantry
Inspect the table travel path, floor area, gantry opening, tabletop, table base, and accessory area.
Look for stools, step platforms, cables, blankets, positioning aids, patient belongings, IV poles, or trash containers blocking movement.
Expected outcome: The table path is clear and no external obstruction is limiting motion.
If clearing an obstruction resolves the issue, verify normal table motion and stop.
Check Patient Setup, Weight, and Positioning Accessories
Confirm that the patient is centered appropriately and that positioning devices are not interfering with gantry clearance or table travel.
Check that arm supports, head holders, immobilizers, straps, cushions, radiation therapy positioning devices, and blankets are properly secured.
Expected outcome: Patient setup does not create a clearance, balance, or movement restriction.
Verify Table Load and Site Policy Limits
Confirm the patient and accessories are within the system’s approved table load limits according to site documentation.
Do not attempt repeated table movement if the system is struggling, stopping, or reporting limit errors under load.
Expected outcome: The system is not being operated outside approved patient table conditions.
Check Emergency Stop and Motion Enable Conditions
Verify that no emergency stop button is pressed at the gantry, operator console, table controls, or room control area.
Confirm that motion enable controls are being used correctly and that the system is not waiting for a required operator confirmation.
Expected outcome: Table movement is not inhibited by an active emergency stop or motion safety condition.
Inspect External Table Controls
Check the table control buttons, hand control, gantry-side controls, and operator console controls for stuck buttons, physical damage, contamination, or inconsistent response.
Test only when safe and with no patient risk.
Expected outcome: The control source responds normally and no control appears stuck or damaged.
If one control works but another does not, document the affected control and remove the system from service if clinical use depends on that control.
Confirm the Table Is Properly Homed or Referenced
Check whether the system is requesting a table home, reference, or initialization movement.
Follow the normal operator-level table reset or homing workflow available to Clinical Engineering and site imaging staff.
Expected outcome: The table position is recognized by the system and motion limits clear.
If the table cannot home or reference correctly, stop and escalate.
Review the Selected Exam Protocol and Scan Range
Confirm the technologist selected the intended PET/CT protocol and patient orientation.
Check whether the planned scan range exceeds table travel limits or conflicts with the current patient position.
Expected outcome: The requested scan range is appropriate for the patient orientation, table position, and selected protocol.
Check Patient Orientation and Registration Setup
Verify head-first vs feet-first, supine vs prone, and PET/CT acquisition setup.
Incorrect patient orientation can make table positioning appear wrong even when table motion is mechanically normal.
Expected outcome: The table position and planned scan range match the intended clinical setup.
Check for Gantry or Table Collision Warnings
Review displayed system messages related to gantry clearance, table position, scan range, or collision protection.
Confirm that no accessory, patient extremity, IV pole, oxygen tubing, or immobilization device is near the gantry path.
Expected outcome: Collision protection is not being triggered by an external setup issue.
Power Cycle Only When Safe and Appropriate
If the table remains in a faulted state with no patient on the table, coordinate with imaging staff before performing an approved system restart or console reboot.
Do not power cycle during active imaging, active patient positioning, or while the patient depends on the system.
Expected outcome: Temporary communication or software state faults may clear without internal repair.
Perform a Controlled Functional Check
With no patient on the table, test basic table movement, height adjustment, in/out travel, and positioning response within normal safe limits.
Confirm smooth movement, correct stopping, no abnormal sounds, and no repeated limit messages.
Expected outcome: Table motion is normal and repeatable before the system is returned to service.
Verify Clinical Readiness Before Returning to Service
Confirm with imaging staff that table movement, positioning, and scan range setup are functioning normally.
If required by site policy, document any functional test or QC check performed after the table issue.
Expected outcome: The system is safe for clinical use and the reported table issue is resolved.
If the Problem Persists
If the Biograph mCT table still will not move correctly, cannot home, reports repeated limit errors, loses position, moves inconsistently, or shows collision/positioning faults after external checks, common external causes have been ruled out.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for Siemens service, repair, or bench evaluation
The likely cause may involve table drive hardware, position sensors, limit switches, motor control, encoder feedback, communication, or system calibration. Clinical Engineering should stop before internal disassembly or unsupported service adjustments.
Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Do not troubleshoot table movement problems on an active patient unless immediate patient safety requires it. If movement is unreliable, have clinical staff move the patient to another imaging system or approved downtime workflow before troubleshooting continues.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"PET/CT technologist reported the Siemens Biograph mCT patient table stopped during positioning and displayed a table limit message before acquisition."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found no obstruction, emergency stop, or accessory interference, but the table continued to report a positioning fault after restart and functional testing."
Resolution
What action was taken.
Example:
"Removed the Biograph mCT from service, labeled it Out of Service, documented repeated table positioning failure, and escalated to Siemens service for repair evaluation."
Helpful Details to Include (If Known)
- Whether a patient was on the table when the issue occurred
- Exact table error or limit message
- PET, CT, or PET/CT workflow affected
- Patient orientation selected
- Scan range entered
- Table height and in/out movement behavior
- Whether emergency stop buttons were checked
- Accessories or positioning devices used
- Obstructions found or ruled out
- Whether table homing/reference completed
- Abnormal sounds, vibration, or jerky motion
- Final device status
Final Thought
Patient table issues on a PET / CT system should be handled carefully because positioning errors can affect both patient safety and image acquisition accuracy. Start with external causes, verify setup and workflow, and escalate when the table cannot move, home, or position reliably. Clear CCR documentation helps service teams understand the failure pattern and supports a safe return to clinical use.
That is successful troubleshooting.