On this page
Asset Type
Manufacturer
Model
What This Guide Helps With
Addresses poor CT images or artifacts caused by patient positioning, external objects, motion, accessories, protocol selection, or calibration-related conditions.
Step-by-Step Troubleshooting
1. Protect the Patient From Unnecessary Repeat Imaging
Do not repeatedly scan a patient to troubleshoot unexplained artifacts. If diagnostic image quality is unreliable, stop clinical use and use another verified imaging system when necessary.
Expected outcome: Unnecessary radiation exposure is avoided.
2. Confirm the Artifact or Quality Complaint
Review what staff observed. Determine whether the issue is noise, streaking, banding, shading, distortion, motion artifact, incomplete anatomy, or another visible problem.
Record which exams, anatomy, protocols, and patients are affected.
Expected outcome: The image-quality problem is clearly characterized.
3. Check Patient Positioning and Motion Factors
Verify patient centering, immobilization, scan positioning, and whether voluntary or involuntary motion could explain the image.
Expected outcome: Patient positioning and movement are either identified as the cause or ruled out.
If proper positioning eliminates the problem on subsequent clinically indicated imaging, troubleshooting may stop after verification.
4. Remove External Objects From the Scan Field
Inspect for cables, ECG leads, jewelry, positioning devices, supports, clothing hardware, blankets, injector components, or other dense objects in or near the scan field.
Expected outcome: No unnecessary external object contributes to artifact.
5. Check Accessories and Table Components
Inspect head holders, cushions, positioning aids, table pads, and removable accessories for damage, contamination, foreign material, or incorrect placement.
Expected outcome: External scanner accessories are correctly installed and artifact-free.
6. Verify Exam and Reconstruction Selection
Confirm that staff selected the intended protocol, scan range, reconstruction, field of view, and other normal clinical settings.
Do not alter restricted service or calibration values.
Expected outcome: Image appearance is not explained by an unintended exam or reconstruction selection.
7. Determine Whether the Problem Is Patient-Specific or System-Wide
Compare with prior acceptable studies or perform an approved phantom/QC check if within Clinical Engineering responsibility.
Do not expose additional patients for comparison.
Expected outcome: The issue is identified as patient/exam-specific or reproduced under controlled conditions.
8. Check Recent Environmental or Service Events
Ask whether the problem began after maintenance, power interruption, system restart, room temperature problem, hardware service, or software/configuration change.
Expected outcome: Any relevant event is identified for escalation or further testing.
9. Perform Approved Image-Quality Verification
Use appropriate approved phantom or quality-control methods to verify scanner performance.
Do not substitute subjective visual judgment for required QC testing.
Expected outcome: Image performance is either verified as acceptable or the artifact is reproducibly confirmed.
If image quality meets required criteria and the original external cause is corrected, troubleshooting is complete.
10. Escalate Persistent Image-Quality Problems
If artifacts remain during controlled testing, remove the scanner from service or restrict use according to site policy. Do not attempt detector calibration, X-ray tube adjustment, or internal component repair outside approved service procedures.
Expected outcome: Unverified image-quality performance is not used for patient diagnosis.
If the Problem Persists
Common external causes have been ruled out. Remaining possibilities may include detector calibration, acquisition electronics, X-ray generation, reconstruction processing, mechanical alignment, environmental influences, or service-level configuration.
The CT scanner should be:
- Removed from service when image quality cannot be verified.
- Labeled Out of Service.
- Sent for repair or qualified service evaluation.
- Evaluated using appropriate Canon documentation, phantoms, and approved test equipment.
- Repaired, calibrated, or configured only by qualified personnel.
Required image-quality and radiation-performance testing must be successfully completed before unrestricted clinical use resumes.
Knowing when to stop external troubleshooting is proper troubleshooting.
Clinical Use Tip
Do not use patient examinations as repeated test scans when artifact cause is unknown; use appropriate phantom or QC methods instead.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"CT staff reported streak artifacts appearing on head studies."
Cause
What was observed during troubleshooting.
Example:
"Clinical Engineering found a removable positioning accessory containing a dense external object in the scan field."
Resolution
What action was taken.
Example:
"Removed the interfering object, inspected the accessory, completed approved image-quality verification, and confirmed the artifact was no longer present."
Helpful Details to Include (If Known)
- Description of artifact.
- Exam and anatomy affected.
- Whether all patients were affected.
- Patient positioning.
- External objects or accessories present.
- Protocol and reconstruction observed.
- Recent service or power event.
- Phantom or QC results.
- Before-and-after image findings.
- Final scanner status.
Final Thought
Avoid unnecessary repeat exposure, rule out patient positioning and external objects first, verify image quality objectively, and escalate persistent artifacts for qualified evaluation.
That is successful troubleshooting.