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What This Guide Helps With
Troubleshooting patient table movement, indexing, scan range, table position, or bed travel issues using safe external checks before repair escalation.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Confirm whether a patient is on the PET / CT table.
If the table is not moving correctly, indexing unexpectedly, stopping during travel, or not aligning to the planned scan range, stop table movement immediately.
Expected outcome: The patient is protected from unexpected motion, incomplete positioning, or unsafe table travel.
If patient safety is affected, remove the patient from the system using the site’s approved procedure before continuing.
Confirm the Exact Table or Positioning Issue
Ask the technologist what occurred and when it occurred.
Identify whether the issue involves:
- Table will not move
- Table movement stops during travel
- Table indexing is inaccurate
- Scan range does not match the planned anatomy
- PET and CT alignment appears incorrect
- Table height or longitudinal travel is limited
- Patient positioning landmarks do not match acquisition setup
- Error occurs during scout/topogram, CT acquisition, PET acquisition, or whole-body workflow
Expected outcome: The reported symptom is clearly defined before troubleshooting continues.
Check for Patient, Accessory, or Room Obstruction
Inspect the table travel path for anything blocking movement.
Check for:
- Patient straps or sheets caught near the table
- IV lines, oxygen tubing, monitoring cables, or injector tubing under tension
- Table pads, positioning aids, arm supports, or head holders interfering with travel
- Trash cans, step stools, chairs, cables, or accessories near the table base
- Patient body habitus or positioning contacting the gantry opening
Expected outcome: The table has a clear travel path with no external obstruction.
If removing an obstruction restores normal table movement, verify operation with staff and stop.
Verify the Patient Is Properly Positioned
Confirm the patient is centered and positioned according to the planned exam.
Check that arms, legs, blankets, immobilization aids, and positioning accessories do not extend into areas that may interfere with gantry clearance or table travel.
Expected outcome: Patient positioning does not create a physical movement limitation or scan range error.
Confirm Table Load and Weight Distribution
Verify that the patient and accessories do not exceed the site-approved table loading limits.
Also check that the patient is not positioned unusually far off-center or unsupported.
Expected outcome: The table is not being asked to move with excessive or poorly distributed load.
If table movement problems only occur with heavier patients or unusual positioning, remove the system from service until evaluated.
Check the Table Control Inputs
Test table movement using the normal operator controls when safe.
Check whether the issue occurs from:
- Gantry controls
- Console controls
- Table-side controls
- Footswitch or hand control, if used
- Workflow-driven automatic table movement
Expected outcome: Clinical Engineering can determine whether the problem follows one control location or affects all table movement.
If only one external control is affected, inspect that control for damage, stuck buttons, contamination, or cable strain.
Inspect Emergency Stop and Safety Stop Conditions
Verify that emergency stop buttons are not engaged.
Check for safety stop, collision, or table interlock messages at the console or gantry display.
Expected outcome: Table motion is not being intentionally inhibited by a safety stop or interlock.
If an emergency stop was activated, do not simply reset and return to use until the reason for activation is understood.
Review System Messages at the Console
Ask staff to show the exact message related to table motion, indexing, scan range, positioning, or acquisition setup.
Record whether the message appears during:
- Startup
- Patient registration
- Topogram/scout
- CT scan setup
- PET bed position planning
- Whole-body acquisition
- Table return or unload position
Expected outcome: The fault timing helps separate workflow setup issues from actual table hardware or position feedback issues.
Confirm Scan Range Planning
Review the planned scan range with the technologist.
Confirm that the topogram/scout image, scan start location, scan end location, PET bed positions, and selected protocol match the intended anatomy.
Expected outcome: The reported scan range issue is not caused by incorrect planning, wrong protocol selection, or incorrect landmarking.
If correcting the planned range resolves the issue, document as a workflow/setup finding and stop.
Verify Patient Landmarking and Table Reference Position
Confirm that the patient was landmarked correctly before the scan.
Check whether the table was moved after landmarking, whether the wrong anatomical reference was selected, or whether the exam was planned from an outdated scout/topogram.
Expected outcome: Table position and scan planning are based on the correct patient reference.
Check PET / CT Workflow Alignment
Confirm whether the issue affects CT-only movement, PET-only bed indexing, or combined PET / CT acquisition.
PET / CT studies depend on accurate table position between CT attenuation correction and PET acquisition.
Expected outcome: Clinical Engineering can determine whether the positioning concern is isolated to one acquisition mode or affects combined system coordination.
Check for Recent Accessory or Table Configuration Changes
Ask whether any table pads, positioning accessories, patient supports, QA phantoms, injector setup, or immobilization devices were recently changed.
Make sure accessories are seated correctly and not shifting during table travel.
Expected outcome: A recent external setup change is identified or ruled out.
Power Cycle Only When Clinically Appropriate
If no patient is on the table and staff confirm it is safe, restart the operator workstation or system according to site practice.
Do not power cycle during an active patient scan unless directed by the clinical team and site policy.
Expected outcome: Temporary software or communication faults clear without unsafe interruption.
If table movement and indexing return to normal after restart, perform a safe functional check before returning the system to use.
Perform a Non-Patient Functional Movement Check
With no patient on the table, test basic table travel, height movement, load/unload position, and scan-range positioning if allowed by site procedure.
Observe for:
- Jerky movement
- Unexpected stopping
- Repeated position errors
- Grinding, clicking, or slipping sounds
- Delayed control response
- Position mismatch between commanded and actual travel
Expected outcome: The table moves smoothly and predictably without fault messages.
Check for Repeated or Intermittent Behavior
Ask whether the issue is constant or intermittent.
Intermittent table indexing or position feedback problems should not be dismissed, especially on PET / CT systems where accurate registration matters.
Expected outcome: The device status is based on repeatable observation, not a single unclear report.
Do Not Override or Force Table Movement
Do not push, pull, bypass, or mechanically force the patient table.
Do not continue scanning if table position accuracy is questionable.
Expected outcome: The system is not damaged further, and patient imaging accuracy is protected.
If the Problem Persists
If table movement, indexing, scan range positioning, or PET / CT alignment remains unreliable after external checks, common user-accessible causes have been ruled out.
The issue may involve internal table drive components, position feedback, motion control communication, calibration, encoder feedback, software coordination, or PET / CT registration-related service functions.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for Siemens service, repair, or bench/system evaluation
Knowing when to stop is proper troubleshooting. A PET / CT system with uncertain table position or scan range accuracy should not be used for patient imaging.
Clinical Use Tip
Do not troubleshoot table motion or scan range problems with an active patient on the table unless immediate safety requires it. Move the patient to a safe position first, then troubleshoot only when table movement will not create risk.
Do not troubleshoot on an active patient. Move the patient to a backup device or approved alternate imaging workflow first so therapy or diagnostic continuity is protected.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Technologist reported that the Siemens Biograph Horizon table stopped during PET bed indexing and the planned scan range did not advance correctly."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found no external obstruction, emergency stop activation, or accessory interference; table position fault repeated during non-patient movement check."
Resolution
What action was taken.
Example:
"Removed PET / CT system from service, labeled Out of Service, documented repeated table indexing fault, and escalated to Siemens service for evaluation."
Helpful Details to Include (If Known)
- Whether a patient was on the table when the issue occurred
- Exact console or gantry message
- Whether CT, PET, or combined PET / CT workflow was affected
- Whether the issue occurred during topogram, CT scan, PET bed indexing, or table unload
- Table position where the issue occurred
- Accessories or positioning aids used
- Any obstruction found
- Emergency stop status
- Control location tested
- Whether movement was smooth, jerky, delayed, or stopped
- Any unusual sounds
- Any unusual heat or smell
- Alarm behavior
- Accessories swapped
- Power behavior
- Environmental factors
- Indicator lights
- Final device status
Final Thought
Patient table issues on a PET / CT system must be handled carefully because table position affects both patient safety and image registration accuracy. Start with external causes, verify workflow and positioning, avoid forcing movement, and escalate when position reliability cannot be confirmed. Clear CCR documentation helps service teams understand the failure and protects clinical operations.
That is successful troubleshooting.