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What This Guide Helps With
Troubleshooting PET daily QC, detector calibration, normalization, or PET readiness failures using safe external checks before service escalation.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Confirm no patient is on the PET/CT table or scheduled for immediate imaging on the affected system.
If the issue is discovered during clinical workflow, stop PET imaging until QC readiness is confirmed acceptable.
Expected outcome: No patient study is performed on a PET system with unresolved detector, calibration, or QC status concerns.
Confirm the Exact PET QC Failure
Review the reported message at the acquisition workstation or PET system console.
Identify whether the issue involves:
- Daily PET QC failure
- Detector block or crystal issue
- Normalization failure
- Calibration not current
- PET acquisition not ready
- Failed blank scan, setup scan, or system check
- Coincidence, count rate, or detector uniformity concern
Expected outcome: The failure type is clearly identified before troubleshooting begins.
Verify the System Is Not in Clinical Use or Warm-Up Delay
Confirm the PET/CT system has completed startup and is not still initializing PET electronics, gantry communication, or acquisition software.
Allow the system to reach normal ready state before repeating QC.
Expected outcome: QC is not attempted while the system is still booting, initializing, or recovering from a prior fault.
If the system becomes ready and QC passes, document the startup timing issue and stop.
Check Room and System Status Indicators
Verify that the PET gantry, CT gantry, acquisition workstation, and operator console show normal ready status.
Check for active error messages, warning icons, interlock messages, or environmental alerts.
Expected outcome: The system status supports running PET QC without unresolved system warnings.
Confirm Required QC Source Is Available and Correct
Verify the correct PET QC source, phantom, or manufacturer-approved daily QC accessory is being used according to site procedure.
Confirm the source is not expired, missing, damaged, incorrectly stored, or substituted with the wrong activity/source type.
Expected outcome: QC is being performed with the correct external source or phantom required for the test.
If the wrong or expired source is found, replace it with the correct approved source and repeat QC.
Verify Source or Phantom Placement
Confirm the source or phantom is positioned exactly as required by the site’s PET QC workflow.
Check for incorrect height, off-center placement, table position error, gantry misalignment, or use of the wrong holder.
PET QC and normalization checks can fail if the system sees poor geometry or unexpected count distribution.
Expected outcome: The source or phantom is centered, stable, and positioned correctly for the selected QC procedure.
If placement correction resolves the QC failure, document the positioning issue and stop.
Check Patient Table Position and Indexing
Verify the table can move normally to the PET QC position and that no table indexing, range, or limit message is active.
Confirm the tabletop is not blocked by accessories, straps, coils, pads, or objects in the bore.
Expected outcome: The table reaches the expected QC position without obstruction or position mismatch.
Inspect PET Bore and Table Area for Obstructions
Visually inspect the PET/CT bore, table, source holder, and surrounding area.
Remove loose objects, patient positioning devices, metal items, contaminated absorbent pads, or anything that could interfere with source geometry or table motion.
Expected outcome: The QC field is clear and the source or phantom is the only intended object in the scan area.
Confirm the Correct QC Workflow Was Selected
Verify the operator selected the correct PET daily QC, detector calibration, normalization, or system setup procedure for the Biograph Horizon workflow.
Make sure a PET QC procedure is not confused with CT calibration, PET/CT alignment, blank scan, normalization, or service-level calibration.
Expected outcome: The selected workflow matches the reported requirement and site QC schedule.
Check Date, Time, and Study/Protocol Context
Confirm the workstation date and time are correct.
Check that the system is not attempting to use an outdated QC record, incorrect calibration file, or previous failed QC state.
Expected outcome: The system’s QC status and timestamps are consistent with the current date and clinical schedule.
Repeat QC One Time After Correcting External Issues
After confirming correct source, positioning, table movement, workflow selection, and system ready status, repeat the PET daily QC or applicable calibration check one time.
Expected outcome: The test completes successfully and the PET system returns to clinical-ready status.
If QC passes, document what was corrected and return the system to service according to site policy.
Review Failure Pattern
If QC fails again, determine whether the same detector, normalization, count rate, or calibration message repeats.
A repeated failure after correct setup suggests a true system issue rather than a user setup problem.
Expected outcome: The fault pattern is identified for escalation.
Check for Environmental or Facility Concerns
Verify there are no obvious room condition issues such as abnormal temperature, humidity, power disturbance, recent outage, water leak, unusual odor, or equipment overheating.
PET detector and electronics stability can be affected by environmental or facility problems.
Expected outcome: No external environmental condition explains the repeated QC failure.
Perform a Controlled System Restart Only if Allowed by Site Policy
If the system is not actively supporting patient care and site policy allows, perform a controlled restart of the affected acquisition workstation or system software workflow.
Do not perform repeated power cycling or service-level resets.
Expected outcome: Temporary software or communication issues clear and QC can be repeated once.
If QC passes after restart, document the restart and final successful QC result.
Do Not Override QC Failure for Routine Clinical Use
Do not return the PET/CT system to routine clinical use if PET daily QC, detector calibration, or normalization remains failed.
Expected outcome: Clinical imaging is not performed with unresolved PET detector readiness or calibration status.
If the Problem Persists
If PET daily QC, detector calibration, or normalization continues to fail after verifying the correct source, placement, table position, workflow selection, workstation status, and basic environmental conditions, common external causes have been ruled out.
The issue is likely related to PET detector electronics, calibration data, normalization files, acquisition system communication, environmental stability, or another internal PET subsystem fault.
The device should be:
- Removed from service
- Labeled Out of Service
- Sent for Siemens service evaluation or qualified bench/system-level repair support
Knowing when to stop is proper troubleshooting. Repeated failed PET QC should not be bypassed without appropriate service review and site imaging quality approval.
Clinical Use Tip
Do not troubleshoot PET QC or calibration failures with a patient waiting on the table. Move the patient to another approved imaging workflow first if the system cannot be cleared quickly and safely. PET QC status directly affects image quality, quantification confidence, and study reliability.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"PET technologist reported the Biograph Horizon failed daily PET QC and would not clear PET readiness for patient imaging."
Cause
What was observed during troubleshooting.
Example:
"Verified correct QC source was available, source placement was corrected, table indexing was normal, but PET daily QC failed again with a repeated detector calibration/normalization-related message."
Resolution
What action was taken.
Example:
"Removed PET/CT system from service, labeled unit Out of Service, notified imaging leadership, and escalated to Siemens service for PET detector and normalization evaluation."
Helpful Details to Include (If Known)
- PET daily QC pass/fail result
- Exact error message or fault code displayed
- Whether the issue was daily QC, detector calibration, normalization, or PET readiness
- QC source or phantom used
- Source expiration status, if applicable
- Source or phantom placement verified
- Table position/indexing checked
- Bore and tabletop checked for obstructions
- Workstation date/time verified
- Whether restart was performed
- Whether the same failure repeated
- Any detector block, count rate, or uniformity message
- Room temperature, humidity, power event, or facility concern
- Final device status
Final Thought
PET QC troubleshooting should stay disciplined and safety-focused. Confirm the simple external factors first: correct source, correct placement, clear table motion, correct workflow, and stable system status. If the failure repeats after those checks, escalation is the safest and most appropriate next step. Clear CCR documentation protects patient safety, supports imaging quality, and gives service a strong starting point.
That is successful troubleshooting.