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What This Guide Helps With
Troubleshooting PET/CT registration, reconstruction, acquisition workstation, image processing, or workflow faults using safe external checks before escalation.
Step-by-Step Troubleshooting
Ensure Patient Safety First
Confirm whether a patient is currently on the PET/CT table or an acquisition is in progress.
If the issue occurs during an active exam, notify nuclear medicine or imaging staff before any workstation, acquisition, or system reset is attempted.
Expected outcome: Patient care is protected and no acquisition data is interrupted without clinical awareness.
If the patient is unstable, uncomfortable, or exam continuation is unsafe, stop troubleshooting and have staff move to the approved downtime or reschedule workflow.
Confirm the Exact Reported Fault
Ask staff what failed and when it occurred.
Identify whether the issue involves:
- PET/CT misregistration
- CT and PET image fusion mismatch
- Reconstruction not starting
- Reconstruction stuck or failed
- Acquisition workstation frozen
- Images not transferring from scanner to workstation
- Incorrect patient/study loaded
- Exam protocol not advancing
- Series missing from reconstructed study
- DICOM send failure after reconstruction
Expected outcome: The symptom is clearly separated into registration, reconstruction, acquisition workstation, or transfer workflow.
Confirm the Exam Was Completed Correctly
Verify with staff whether the PET acquisition, CT acquisition, or both completed successfully.
Check whether the fault occurred:
- Before scan start
- During acquisition
- After acquisition
- During reconstruction
- During image review
- During DICOM send or archive transfer
Expected outcome: Troubleshooting is focused on the correct stage of the PET/CT workflow.
If the scan did not complete, do not assume a workstation failure. The issue may involve acquisition interruption, patient motion, table position, protocol setup, or system readiness.
Check for Patient Motion or Positioning-Related Registration Issues
For PET/CT registration complaints, ask whether the patient moved between CT and PET acquisition.
Check whether the patient position, arm position, table setup, immobilization aids, or scan range changed between portions of the exam.
Expected outcome: Obvious motion or positioning causes of PET/CT misregistration are identified before suspecting system failure.
If patient motion or repositioning explains the mismatch, document the finding and have clinical staff determine whether repeat imaging is needed.
If this resolves the issue, stop.
Verify Correct Patient and Study Selection
At the acquisition or processing workstation, confirm staff are viewing the correct patient, accession, exam date, and series.
Check for duplicate patient entries, split studies, incomplete series, or manually selected prior images.
Expected outcome: The displayed PET and CT data belong to the same exam and patient.
If incorrect study selection caused the problem, have authorized imaging staff correct the workflow according to site policy.
If this resolves the issue, stop.
Check Workstation Display and Application Status
Confirm whether the acquisition or reconstruction workstation is responsive.
Check for:
- Frozen application
- Mouse or keyboard not responding
- Blank monitor
- Error message on screen
- Login/session issue
- Application open but not advancing
- Reconstruction queue stuck
- System clock or patient list mismatch
Expected outcome: The issue is identified as either a workstation usability problem or a deeper application/system fault.
Do not force restart during active acquisition unless clinical staff confirm the exam is complete and data safety is addressed.
Check Basic Workstation Power and External Connections
Inspect workstation power, monitor power, display cables, keyboard, mouse, and network cable connections.
Confirm the workstation is powered on and connected to the expected network port.
Expected outcome: Simple external connection problems are ruled out.
If a loose monitor, keyboard, mouse, or network cable caused the fault, reconnect it, verify normal operation with staff, document the action, and stop.
Review Visible Error Messages
Record any displayed error message exactly as shown.
Look for wording related to:
- Reconstruction failed
- Database unavailable
- Acquisition incomplete
- PET not ready
- CT not available
- Registration failed
- Series missing
- Network unavailable
- Archive unavailable
- License or application startup error
- Disk space or storage warning
Expected outcome: The fault is documented accurately for repair escalation if needed.
Do not clear messages before capturing screenshots or writing down the displayed wording.
Check Reconstruction Queue or Processing Status
Ask staff whether reconstruction is queued, processing, paused, failed, or missing.
Confirm whether only one patient is affected or multiple studies are failing.
Expected outcome: The issue is separated into a single-study problem versus a system-wide reconstruction issue.
If only one study failed, the cause may relate to exam data, protocol selection, motion, or incomplete acquisition.
If multiple studies fail, suspect workstation, processing server, storage, software, or network-related failure and escalate.
Confirm Storage and Archive Workflow Status
Ask whether images can be viewed locally and whether only archive/PACS transfer is failing.
Check whether reconstructed images exist locally but are not reaching PACS.
Expected outcome: The issue is separated into reconstruction failure versus DICOM/archive communication failure.
If images reconstruct locally but do not send, troubleshoot as a DICOM or network transfer issue rather than a scanner acquisition fault.
Check Network Indicators and Known Downtime Conditions
Verify whether the acquisition workstation, reconstruction system, PACS, RIS, or network is affected by a known outage.
Check link lights at accessible network ports if safe and allowed by site practice.
Expected outcome: Network or enterprise downtime is ruled in or out before equipment repair is requested.
If a known network or PACS outage is confirmed, document the finding and route according to site IT/imaging informatics workflow.
If this resolves the issue, stop.
Confirm PET/CT System Readiness After Normal Startup
If the system was recently started, restarted, or recovered from downtime, confirm with staff whether startup completed normally.
Check whether the acquisition workstation, scanner console, reconstruction application, and patient/study worklist are all available.
Expected outcome: The system is not being evaluated before required startup processes are complete.
Do not perform repeated power cycles. Repeated restarts can worsen data availability problems and delay proper service diagnosis.
Check for Recent Changes
Ask whether anything changed before the issue began.
Examples include:
- Software update
- Network change
- PACS destination change
- RIS/worklist issue
- New protocol
- Workstation replacement
- Power event
- Room shutdown
- Service activity
- Failed daily QC or calibration
- New user workflow
Expected outcome: Recent changes are identified as possible contributors.
Document the timing because it helps Siemens service, imaging informatics, or internal IT isolate the problem faster.
Verify Whether CT-Only or PET-Only Functions Are Affected
Ask staff whether CT acquisition works independently and whether PET acquisition/reconstruction works independently.
Expected outcome: The fault is narrowed to PET acquisition, CT acquisition, fused registration, reconstruction, or workstation processing.
If CT and PET both fail, suspect a broader workstation, system communication, or workflow issue.
If only fused image registration fails, focus on patient motion, scan range, study pairing, processing workflow, or registration software fault.
Perform Only Approved User-Level Recovery
If clinical staff confirm the patient is clear, acquisition is complete, and no data loss risk exists, follow site-approved user-level recovery steps only.
This may include closing and reopening the application, logging out and back in, or performing a normal workstation restart if permitted by site policy.
Expected outcome: Temporary workstation or application lockup is cleared without unsafe service intervention.
If normal operation returns, verify with staff that acquisition, reconstruction, image display, and transfer are working.
If this resolves the issue, stop.
Verify Function With a Safe Non-Patient Workflow
When appropriate, have authorized imaging staff confirm system function using a safe test, phantom, prior study review, or non-patient workflow allowed by department policy.
Expected outcome: The workstation, reconstruction process, registration display, and transfer pathway are verified before clinical use resumes.
Do not use a patient exam as the first functional test after an unresolved workstation or reconstruction fault.
Determine Whether the System Can Return to Service
The system may return to service only if:
- No active error remains
- Workstation is responsive
- Correct patient/study workflow is restored
- Reconstruction completes normally
- PET/CT registration appears acceptable to qualified imaging staff
- Images transfer or store according to site workflow
- Clinical staff confirm the system is safe for use
Expected outcome: Return-to-service decision is based on verified system function, not assumption.
If the Problem Persists
If registration, reconstruction, or acquisition workstation faults continue after external checks, common workflow and connection issues have been ruled out.
Remove the Biograph Horizon from clinical use if the issue affects acquisition, image reconstruction, PET/CT registration accuracy, patient data integrity, or clinical image availability.
The device should be:
- Removed from service
- Labeled Out of Service
- Escalated for Siemens service, imaging informatics, IT, or bench/system evaluation as appropriate
Knowing when to stop is proper troubleshooting. PET/CT registration and reconstruction faults can affect diagnostic confidence, patient data integrity, and clinical workflow. Do not continue repeated restarts or workaround attempts when the cause is not clearly external.
Clinical Use Tip
Do not troubleshoot acquisition, reconstruction, or registration faults on an active patient unless the clinical team confirms it is safe. Move the patient out of the workflow first when possible, protect acquired data, and verify image integrity before the system is returned to clinical use.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Nuclear medicine staff reported that the Biograph Horizon acquisition workstation completed the scan, but PET/CT reconstruction failed and fused images were not available for review."
Cause
What was observed during troubleshooting.
Example:
"Workstation, network, patient/study selection, and visible external connection checks were completed; reconstruction queue remained failed for multiple studies."
Resolution
What action was taken.
Example:
"System was removed from service, labeled Out of Service, error details were documented, and Siemens service/imaging informatics escalation was initiated."
Helpful Details to Include (If Known)
- Outlet or UPS status checked
- Workstation powered on normally
- Monitor, keyboard, mouse, and network cables checked
- Acquisition completed or failed
- PET-only, CT-only, or fused PET/CT issue identified
- Registration mismatch location or pattern
- Reconstruction queue status
- Exact error message recorded
- Patient motion or repositioning reported
- PACS/DICOM transfer status
- Worklist/RIS status
- Network link lights observed
- Known IT or PACS outage checked
- Recent software, network, or protocol changes
- Unusual sounds, heat, smell, or power events
- Final device status
Final Thought
PET/CT troubleshooting should protect the patient first, then separate acquisition, reconstruction, registration, workstation, and network symptoms logically. External checks can resolve simple workflow or connection issues, but persistent reconstruction or registration faults require escalation because image accuracy and data integrity are directly involved. Clear CCR documentation helps service teams identify the failure path faster and supports safe return to clinical use.
That is successful troubleshooting.