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What This Guide Helps With
Addresses unavailable gantry or patient-table motion caused by interlocks, obstruction, positioning controls, emergency stops, accessories, or external conditions.
Step-by-Step Troubleshooting
1. Protect the Patient From Unintended Movement
Do not troubleshoot unreliable gantry or table motion while a patient depends on the system. Support or remove the patient safely before testing positioning functions.
Prevent unintended movement of the table, gantry, accessories, tubing, monitoring leads, or other attached equipment.
Expected outcome: The patient and attached equipment are protected before motion troubleshooting begins.
2. Confirm Which Motion Is Unavailable
Determine whether the problem affects table longitudinal movement, table height, gantry positioning, one control location, or all positioning functions.
Ask whether motion stopped during positioning or was unavailable before the patient was placed on the table.
Expected outcome: The affected motion and circumstances are clearly identified.
If motion is now normal and repeatable, proceed to final verification.
3. Inspect for Physical Obstructions
Check around the table, gantry opening, floor, covers, patient supports, positioning aids, cables, blankets, accessories, and nearby equipment.
Do not force a mechanism that appears mechanically blocked.
Expected outcome: Nothing external obstructs safe motion.
If removing an obstruction restores normal movement, inspect for damage and complete functional verification.
4. Check Emergency-Stop and Safety Controls
Inspect accessible emergency-stop controls and safety interlocks for activation or abnormal condition.
Do not bypass an interlock to restore motion.
Expected outcome: Safety controls are in their normal permitted state.
If safely restoring an activated control returns normal motion, proceed to verification.
5. Check Patient and Accessory Positioning
Verify that the patient, mattress, head holder, supports, immobilization devices, injector tubing, monitoring cables, and other accessories are positioned without interfering with expected travel.
Expected outcome: Accessories and patient-support items do not restrict motion.
If repositioning resolves the issue, verify all required motion before clinical use.
6. Compare Available Motion Controls
Test approved external positioning controls from the normal operator locations, without a patient on the system.
Determine whether the problem follows one control interface or affects all control points.
Expected outcome: Motion either functions consistently or the failure is narrowed to a specific control path.
If one external control was obstructed or incorrectly engaged and normal operation returns, complete verification and stop.
7. Check System Ready Status
Confirm that the CT system has completed startup and is not displaying a condition that intentionally inhibits motion.
Record any message exactly.
Expected outcome: The scanner is in a state where positioning motion should be available.
If clearing an approved external condition restores normal motion, proceed to final testing.
8. Inspect Accessible External Components
Check visible table controls, covers, hand controls, cabling, and accessible connectors for damage, looseness, contamination, or evidence of impact.
Do not remove covers or enter internal motion assemblies.
Expected outcome: No external damage or disconnected component explains the fault.
If an approved external connection is restored and motion becomes normal, verify the system before use.
9. Perform Final Functional Verification
With the scanner unloaded, verify required table and gantry positioning functions through their normal operating range as permitted by approved procedures.
Confirm movement is smooth, controlled, repeatable, and stops appropriately.
Expected outcome: Required motion functions operate normally without unexpected movement or repeated faults.
If achieved, troubleshooting is complete.
10. Escalate Unresolved Motion Failure
If positioning remains unavailable, intermittent, jerky, uncontrolled, or otherwise unreliable, remove the system from service. Do not troubleshoot internal motors, drives, encoders, braking systems, or motion-control electronics without qualified service authorization.
Expected outcome: Unsafe or unreliable positioning equipment is not returned to patient use.
If the Problem Persists
Common external causes have been ruled out. Remaining possibilities may include internal motion-control systems, sensors, drive mechanisms, safety interlocks, control electronics, or service-level configuration faults.
The CT scanner should be:
- Removed from service.
- Labeled Out of Service.
- Sent for repair or qualified service evaluation.
- Evaluated using appropriate Canon documentation and approved test equipment.
- Repaired or configured only by qualified personnel.
Following repair, verify all affected positioning functions, safety stops, scanner readiness, and any required manufacturer return-to-service tests.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Do not attempt repeated table or gantry movement with a patient attached to injectors, IV lines, monitors, or other equipment until predictable motion is confirmed.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"CT staff reported the patient table would not advance into the gantry."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found an external positioning accessory and attached cable were interfering with table travel."
Resolution
What action was taken.
Example:
"Repositioned the accessory and cable, verified unobstructed table and gantry motion without a patient, and confirmed normal system operation."
Helpful Details to Include (If Known)
- Exact motion affected.
- Whether one or all controls were affected.
- Emergency-stop status.
- Physical obstruction found.
- Patient accessory configuration.
- Visible cable or control damage.
- Exact displayed message.
- Motion behavior before and after correction.
- Final positioning verification results.
- Final device status.
Final Thought
Protect the patient from unintended movement, eliminate obstructions and external interlocks first, verify reliable operation, and escalate any unresolved or unpredictable motion condition.
That is successful troubleshooting.