Siemens Healthineers Symbia Evo

Daily Uniformity, Flood, or Center-of-Rotation QC Failure

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Asset Type

Nuclear Medicine System

Manufacturer

Siemens Healthineers

Model

Symbia Evo

What This Guide Helps With

Troubleshooting failed daily uniformity, flood, detector QC, or center-of-rotation checks before repair escalation.

Step-by-Step Troubleshooting

Ensure Patient Safety First

Confirm the Symbia Evo is not being used for an active patient study.

If daily QC, flood uniformity, or center-of-rotation testing has failed, do not release the system for patient imaging until QC status is resolved according to site policy.

Expected outcome: No patient study is performed on a nuclear medicine system with questionable detector or rotational accuracy.

Confirm the Exact QC Failure

Review the operator report, QC screen, or failed test result.

Identify whether the failure involves:

Expected outcome: The failure is narrowed to image quality, detector response, rotational alignment, acquisition setup, or processing.

Confirm the System Was Not Used Clinically After the Failure

Ask Nuclear Medicine staff whether any patient studies were performed after the failed QC.

If studies were performed, notify the department lead or physicist according to site policy.

Expected outcome: Any possible clinical impact is identified and escalated appropriately.

Check the Room and System Status

Confirm the system is powered on normally, fully initialized, and not displaying gantry, detector, table, or acquisition workstation errors.

Look for warning indicators, unusual noises, abnormal detector motion, or startup faults.

Expected outcome: The system is in a stable operating state before QC is repeated.

Verify the QC Procedure Was Set Up Correctly

Ask the technologist to confirm the correct daily QC protocol was selected.

Check that the expected detector, collimator condition, acquisition type, matrix, energy window, and isotope selection were used.

Expected outcome: The failed QC was not caused by an incorrect protocol or acquisition setup.

Confirm Source Selection and Activity

Verify that the correct flood source or point source was used for the QC test.

Confirm the source activity is appropriate, not expired, and within the range expected by Nuclear Medicine or Physics procedure.

Expected outcome: The detector is being tested with the correct source strength and isotope.

Check Source Positioning

For flood uniformity testing, confirm the flood source was positioned flat, centered, and at the correct distance from the detector.

For center-of-rotation testing, confirm the point source was correctly positioned according to the site’s QC procedure.

Expected outcome: The failure is not caused by source misalignment or incorrect geometry.

Check for Obstructions Between Source and Detector

Inspect the area between the source and detector for attenuation or shielding issues.

Remove unnecessary objects, lead markers, loose shielding, patient positioning aids, or other materials that could interfere with the flood image.

Expected outcome: The detector has a clear, unobstructed view of the source.

Confirm Collimator Status

Verify the correct collimator is installed for the intended QC procedure, if extrinsic testing is being performed.

Confirm the collimator is fully seated, recognized correctly by the system, and not physically damaged.

Expected outcome: QC is not failing because of the wrong, loose, or incorrectly recognized collimator.

Review the Flood Image Appearance

If available, review the failed flood image with Nuclear Medicine or Physics.

Look for obvious nonuniformity patterns such as:

Expected outcome: The image pattern helps separate a setup problem from a detector or collimator issue.

Check Whether One Detector or Multiple Detectors Are Affected

Determine whether the failure occurs on one detector head or both.

If only one detector fails, compare the failed image and count statistics to the passing detector.

Expected outcome: The issue is narrowed to one detector path, shared setup, source condition, or system-wide acquisition problem.

Check Count Rate and Acquisition Time

Confirm the expected count rate was reached and the acquisition was not stopped early.

Low activity, incorrect source distance, wrong isotope selection, or early termination can cause failed or unreliable QC results.

Expected outcome: The QC acquisition collected enough valid counts for proper evaluation.

Check Energy Peaking or Photopeak Status

Review whether the detector was correctly peaked for the isotope used.

If the photopeak is incorrect or unstable, coordinate with Nuclear Medicine or Physics before repeating QC.

Expected outcome: Uniformity failure is not being caused by incorrect energy window or peaking conditions.

Repeat QC Only After Correctable Setup Issues Are Addressed

If an obvious setup issue is found, correct it and have qualified staff repeat the appropriate QC test.

Examples include repositioning the source, selecting the correct protocol, removing an obstruction, or correcting collimator setup.

If the repeat QC passes and the site’s release criteria are met, document the correction and return the system to service.

Expected outcome: The issue is resolved by correcting an external or procedural cause.

Check Center-of-Rotation Setup

If center-of-rotation QC failed, confirm the correct source type, source position, detector configuration, gantry motion path, and acquisition protocol were used.

Ensure nothing interfered with detector movement or gantry rotation during the test.

Expected outcome: The failure is not caused by incorrect point source placement, setup geometry, or motion obstruction.

Check for Gantry or Detector Motion Faults

Review whether the system displayed any motion, positioning, or limit errors during center-of-rotation acquisition.

If motion was abnormal, do not continue repeated QC attempts without further evaluation.

Expected outcome: A mechanical or positioning problem is identified before additional testing is attempted.

Review Recent Changes

Ask whether there were recent changes such as:

Expected outcome: Recent changes help identify a likely cause or escalation path.

Perform a Controlled Restart Only If Appropriate

If the issue appears related to workstation communication, acquisition software, or a frozen QC process, perform a controlled restart according to site procedure.

Do not restart during active acquisition, motion, or patient use.

Expected outcome: Temporary software or communication issues are cleared before QC is repeated.

Do Not Continue Repeated Failed QC Attempts

If QC fails again after external setup, source, collimator, and acquisition checks are completed, stop troubleshooting.

Repeated failures may indicate detector, gantry, calibration, electronics, or processing issues requiring service evaluation.

Expected outcome: The device is not repeatedly tested without a safe path to resolution.

If the Problem Persists

If daily uniformity, flood, or center-of-rotation QC continues to fail after checking setup, source activity, source positioning, collimator status, count statistics, acquisition settings, and workstation status, common external causes have been ruled out.

The Symbia Evo should be removed from clinical use, labeled Out of Service, and sent for repair, physics review, or bench/service evaluation according to site policy.

Knowing when to stop is proper troubleshooting. A nuclear medicine system that fails QC should not be returned to patient imaging until the failure is resolved and required QC passes.

Clinical Use Tip

Do not troubleshoot QC failures around an active patient study unless the patient is safely clear of the system. If QC failure affects clinical availability, move patient imaging to another approved system or follow the department downtime workflow.

Work Order Documentation (CCR Method)

CCR = Complaint, Cause, Resolution

Complaint

What was reported by the clinical staff.

Example:
"Nuclear Medicine reported that the Siemens Symbia Evo failed daily flood uniformity QC and could not be released for patient imaging."

Cause

What was observed during troubleshooting.

Example:
"Checked source setup, collimator seating, acquisition protocol, count rate, and detector status; repeat QC continued to fail on one detector."

Resolution

What action was taken.

Example:
"Removed the Symbia Evo from service, labeled the system Out of Service, notified Nuclear Medicine leadership, and escalated for service and physics review."

Helpful Details to Include (If Known)

Final Thought

Daily QC protects patient safety by confirming detector response, image uniformity, and rotational accuracy before clinical imaging. Clinical Engineering troubleshooting should move logically from setup, source, collimator, and acquisition checks to appropriate escalation. Clear CCR documentation helps show what was checked, what was ruled out, and why the system was removed from service or returned to use.

That is successful troubleshooting.

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