On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
Detector calibration failure, image artifact risk, scan inhibit, or calibration abort caused by setup, environmental, or detector-related conditions.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Do not troubleshoot detector calibration failures during an active patient exam unless the patient is no longer on the table and scanning has stopped.
Action:
- Stop the exam if calibration failure prevents safe imaging.
- Remove the patient from the scanner room if additional troubleshooting is needed.
- Use another CT scanner if urgent imaging is required.
Expected outcome: Patient care continues safely without repeated failed scan attempts.
Verify the Reported Calibration Failure
Confirm the exact error, when it occurs, and whether it happens during startup, air calibration, daily QC, or a patient scan workflow.
Action:
- Review the operator console message.
- Note whether the calibration starts and then fails, or never begins.
- Check whether the system reports detector, DAS, calibration, gantry, tube, or environmental errors.
- Record the error code or full message if available.
Expected outcome: The failure is confirmed and not confused with a separate warm-up, tube, or reconstruction issue.
Confirm No Patient, Positioning Aid, Phantom, or Object Is in the Scan Field
Detector calibration usually requires a clean air path with nothing obstructing the beam.
Action:
- Verify the table is clear.
- Remove positioning pads, straps, holders, phantoms, contrast tubing, or other objects from the scan field.
- Confirm the table is positioned as required for calibration.
- Look through the bore for anything that could block the beam path.
Expected outcome: Calibration completes if the failure was caused by an obstruction or incorrect setup.
If this resolves the issue, return the scanner to service after successful QC or site-required verification.
Check Gantry and Room Conditions
Detector calibration can fail if the scanner or room environment is outside normal operating conditions.
Action:
- Confirm the room temperature is within the facility’s normal CT operating range.
- Check for unusual heat, humidity, or recent HVAC issues.
- Listen for abnormal gantry fan noise.
- Confirm air vents near the scanner are not blocked.
- Ask staff whether the room recently had power, HVAC, or temperature problems.
Expected outcome: Environmental issues are identified or ruled out.
Why it matters: Detector response can drift with temperature changes, and unstable environmental conditions can prevent a valid calibration.
Verify System Warm-Up Status
Some calibration failures occur when the system has not fully stabilized after startup, power loss, or extended idle time.
Action:
- Confirm the scanner completed startup normally.
- Verify required tube warm-up or system preparation steps were completed.
- Allow the system to stabilize if it was recently powered on.
- Repeat the calibration only after the system is ready.
Expected outcome: Calibration passes if the failure was caused by an unstable startup or incomplete warm-up condition.
Check for Related Tube, Exposure, or High Voltage Errors
Detector calibration depends on a proper X-ray exposure. A detector calibration failure may actually be caused by exposure inhibit, tube readiness, or generator-related issues.
Action:
- Review the error history for tube, generator, exposure inhibit, rotor, high voltage, or cooling errors.
- Confirm the system can perform required warm-up exposures.
- Do not repeatedly force calibration if exposure-related errors are present.
Expected outcome: Exposure-related problems are identified before assuming detector failure.
Why it matters: The detector cannot calibrate correctly if the system cannot produce a stable exposure.
Check Console Workflow and Calibration Selection
Incorrect calibration type or interrupted workflow can cause failed or incomplete calibration.
Action:
- Confirm the correct calibration or QC routine was selected.
- Verify the operator did not cancel or interrupt the process.
- Make sure the scanner is not in a partial exam state.
- Close unnecessary applications or workflows if the console is sluggish.
- Restart the application or system only if allowed by site procedure.
Expected outcome: Calibration completes if the failure was caused by workflow interruption or incorrect calibration selection.
Perform a Controlled System Restart
A temporary software, console, or communication fault may prevent calibration from completing.
Action:
- Confirm no patient is on the table.
- Follow the site-approved shutdown and restart process.
- Allow the scanner to fully boot and stabilize.
- Retry the required calibration or QC routine.
Expected outcome: Calibration completes if the issue was a temporary communication or software state fault.
Inspect External Indicators and Listen for Abnormal Operation
Clinical Engineering should look for signs that the issue may be hardware-related before escalating.
Action:
- Check for abnormal gantry sounds during calibration.
- Observe for warning indicators on system components, if visible.
- Note any unusual odor, heat, vibration, or fan noise.
- Confirm there are no visible cable disconnections, fluid leaks, or physical damage around the scanner, table, or console area.
Expected outcome: External signs of hardware failure are documented and the device is not repeatedly operated if unsafe.
Review Recent Service, Power, or Room Events
Detector calibration failures can occur after service activity, power interruptions, room temperature swings, or scanner downtime.
Action:
- Ask staff whether the scanner was recently serviced.
- Check whether the room had a power outage or breaker event.
- Confirm whether failures started after software updates, detector service, tube replacement, or gantry work.
- Document the timing of the first failure.
Expected outcome: Recent changes are identified and can be shared with service support.
Repeat Calibration Only After Correctable Issues Are Addressed
Do not repeatedly run failed calibrations without correcting a likely cause.
Action:
- Remove obstructions.
- Confirm room conditions are stable.
- Confirm warm-up is complete.
- Confirm no exposure or gantry errors are active.
- Retry calibration once or per site policy.
Expected outcome: Calibration either completes successfully or fails consistently after external causes are ruled out.
If the Problem Persists
If detector calibration continues to fail after patient safety, setup, obstruction, room condition, warm-up, exposure readiness, workflow, and restart checks are completed, the issue is likely internal.
The scanner should be:
- Removed from clinical service
- Labeled Out of Service
- Escalated for GE service or qualified CT bench/service evaluation
Possible internal causes may include detector module issues, DAS communication faults, calibration data corruption, generator/exposure instability, or gantry electronics problems. Clinical Engineering should stop at this point unless trained, authorized, and equipped for CT service procedures.
Knowing when to stop is proper troubleshooting.
Clinical Use Tip
Do not allow repeated patient scan attempts after detector calibration failure. Calibration problems can affect image quality and diagnostic reliability. Move the patient to another scanner before continuing care.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"CT staff reported the GE Revolution scanner failed detector calibration during daily QC and would not clear for patient scanning."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found no patient or object in the bore, room conditions appeared stable, warm-up was completed, and the failure repeated after restart."
Resolution
What action was taken.
Example:
"Scanner was removed from service, labeled Out of Service, error details were documented, and GE service was contacted for detector calibration failure evaluation."
Helpful Details to Include (If Known)
- Exact detector calibration error message or code
- Whether failure occurred during startup, air calibration, daily QC, or exam setup
- Whether the table and bore were clear
- Room temperature or HVAC concerns
- Recent power outage or system restart
- Recent service, tube replacement, software update, or detector work
- Tube warm-up completion status
- Related exposure, generator, DAS, or gantry errors
- Abnormal sounds, heat, odor, or fan behavior
- Whether calibration passed or failed after restart
- Final device status
Final Thought
Detector calibration failures should be approached logically and safely. Rule out setup issues, blocked scan field, environmental instability, incomplete warm-up, exposure problems, and workflow errors before assuming detector failure. If the problem remains, remove the CT scanner from service and escalate with clear documentation.
That is successful troubleshooting.