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What This Guide Helps With
This guide assists Clinical Engineering in troubleshooting situations where a Siemens Healthineers SOMATOM Series CT scanner produces image artifacts such as rings or streaks. These artifacts can affect diagnostic quality and may be caused by detector issues, calibration errors, or external factors. The guide focuses on external checks first, avoiding internal board-level repairs, and emphasizes patient safety.
Step-by-Step Troubleshooting
Verify Scan Parameters and Protocols
- Ensure the correct scan protocol is selected. Incorrect reconstruction algorithms can produce streaks or rings.
- Check if previous scans on the same protocol produced similar artifacts.
- Why: Misconfigured settings are a common source of image artifacts.
Inspect the Detector and Gantry
- Check the detector array for visible damage or obstruction.
- Ensure no foreign objects are inside the gantry (tools, positioning devices, cables).
- Why: Physical issues can cause ring artifacts due to faulty detector elements.
Check Patient Positioning
- Verify the patient is centered and stable on the table.
- Remove metallic objects or accessories that could introduce streaks.
- Why: Misalignment or high-density objects create streak artifacts.
Examine Cables and Connections
- Ensure all detector, gantry, and power connections are secure.
- Swap or reseat cables if possible to rule out intermittent connection faults.
- Why: Loose or damaged cables can create intermittent signal errors visible as artifacts.
Run Detector Calibration / Air Scan
- Perform system calibration or air scan according to standard procedures.
- Document calibration success or failure.
- Why: Detector calibration corrects for sensitivity variations that lead to ring artifacts.
Check for Software Updates or Reconstruction Errors
- Confirm the system software is current.
- Reconstruct the image using a different algorithm or workstation to rule out reconstruction software issues.
If the Problem Persists
External and calibration checks have been exhausted.
Device should be:
- Removed from service.
- Labeled Out of Service.
- Sent for vendor repair or bench evaluation.
Remember: stopping before internal disassembly is proper troubleshooting.
Clinical Use Tip
- Do not scan patients on a machine showing unexplained image artifacts.
- Move the patient to a functional scanner for safety and diagnostic integrity.
- Only perform troubleshooting when the scanner is idle and safe to operate.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
“CT images show rings and streaks affecting diagnostic quality.”
Cause
What was observed during troubleshooting.
Example:
Detector calibration check failed; no visible gantry or patient positioning issues.
Resolution
What action was taken.
Example:
Performed air scan and calibration; if unresolved, removed unit from service and scheduled vendor repair.
Helpful Details to Include
- Scan protocol used
- Detector calibration logs
- Any unusual sounds or error messages during scan
- Presence of metallic objects in the scan field
- Software version and reconstruction algorithm
Final Thought
Proper troubleshooting ensures patient safety and preserves image quality. Starting with external checks, calibration, and protocol verification avoids unnecessary internal intervention. Clear documentation supports both patient safety and efficient repair escalation.
That is successful troubleshooting.