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What This Guide Helps With
Troubleshooting incorrect light field, abnormal collimator blade movement, centering concerns, or suspected tube-to-detector alignment issues before repair escalation.
Step-by-Step Troubleshooting
1. Ensure Patient and Radiation Safety First
Remove the radiographic room from clinical use until accurate collimation and alignment can be confirmed.
Do not troubleshoot positioning, collimation, or alignment concerns during a patient examination. If the concern occurred during use, direct staff to an alternate imaging room or approved backup workflow.
Expected outcome: No patient is exposed using equipment with unresolved collimation or alignment concerns.
Why it matters: An inaccurate light field or tube alignment concern may increase repeat imaging risk or create anatomy cutoff and unnecessary radiation exposure.
2. Confirm the Exact Reported Problem
Obtain the complaint from imaging staff and reproduce the concern without a patient present. Determine whether the issue is:
- Collimator light field does not illuminate.
- Light field is dim, intermittent, distorted, or uneven.
- Collimator blades will not open or close correctly.
- Blade motion is slow, noisy, asymmetric, or stops unexpectedly.
- The displayed or visible field does not appear centered to the detector or receptor.
- The tube head appears physically rotated, angled, or not locking as expected.
- The issue occurs only during a specific exam setup, receptor position, or automatic collimation workflow.
Record any displayed system message, unusual sound, recent impact, service activity, or room event.
Expected outcome: The failure is clearly identified before testing or escalation.
3. Visually Inspect the Tube Head and Collimator Exterior
Inspect the Eleva Tube Head and collimator assembly externally for:
- Cracked, loose, shifted, or damaged covers.
- Evidence of impact or collision.
- Loose accessories or objects obstructing the collimator face.
- Visible damage near the light field window.
- Abnormal tube head sag, rotation, or failure to remain in the selected position.
Do not remove covers or attempt internal alignment adjustments.
Expected outcome: No external damage, obstruction, or obvious mechanical displacement is present.
If damage, impact evidence, or unstable positioning is found: Stop testing, remove the system from service, and escalate for repair.
4. Verify the System Is Fully Powered and Ready
Confirm that the system powers on normally and that the acquisition workstation and tube head interface are operational.
Check for:
- Normal startup completion.
- Active fault or warning messages.
- Responsive tube head controls.
- Normal room-ready status before attempting collimator operation.
The DigitalDiagnost C90 uses the Eleva Tube Head for in-room control, including collimation-related workflow functions.
Expected outcome: The system is fully operational without system faults that could explain unavailable or abnormal collimator control.
If a system fault is active: Document the message and address that fault before continuing collimator assessment.
5. Check Collimator Light Field Operation
With the unit out of patient use and positioned safely over the table or wall receptor area, activate the collimator light field using the normal user control.
Observe whether the field:
- Turns on consistently.
- Is bright enough to identify the illuminated area.
- Appears rectangular and evenly defined.
- Remains stable without flickering or dropping out.
- Matches the approximate blade opening indicated by the controls.
Expected outcome: A clear, stable light field appears when activated.
If the light does not illuminate, flickers, is severely dim, or produces an irregular field: Stop clinical use and escalate for collimator evaluation.
6. Check for External Obstruction or Contamination at the Light Field Exit
Inspect the external collimator face and light exit area for removable contamination, tape residue, labels, accessory interference, or other obstruction that could distort the projected light field.
Clean only according to approved external cleaning practices. Do not open the collimator housing.
Expected outcome: The light field exit area is clean and unobstructed.
If cleaning or removal of an external obstruction restores a normal light field: Confirm normal operation through appropriate quality verification, document the correction, and return the system to service only after acceptance criteria are met.
7. Verify Collimator Blade Response Through Available Controls
Using the normal collimation controls at the tube head or workstation, command the field smaller and larger while observing the light field.
Check whether:
- All field edges move when commanded.
- The field opens and closes smoothly.
- The blades stop at the selected field boundary.
- Movement is symmetrical and repeatable.
- Manual control responds if an automatic collimation workflow is suspected of contributing to the complaint.
Philips identifies the DigitalDiagnost C90 as using Eleva Tube Head control to support collimation workflow, and optional live-camera functionality may assist in viewing the collimated area.
Expected outcome: The visible light field changes smoothly and consistently with the selected collimation input.
If a blade does not move, moves unevenly, binds, chatters, or fails to repeat: Remove the system from service and escalate for authorized service evaluation.
8. Confirm the Issue Is Not Caused by Exam Setup or Detector Selection
Review whether the concern occurs with:
- One specific exam protocol.
- Table imaging only.
- Wall stand imaging only.
- One detector or receptor selection.
- Automatic collimation behavior versus manual adjustment.
- An incorrect active receptor or selected acquisition geometry.
Re-select the correct receptor and perform a non-patient setup check using an appropriate room configuration.
Expected outcome: The selected imaging receptor and geometry match the intended exam setup, and collimator behavior is consistent across applicable positions.
If the issue is isolated to one receptor position or configured workflow: Document that pattern and escalate with those details for more efficient service evaluation.
9. Check Tube Positioning, Rotation, and Locking Behavior
Move the tube head only through normal operator positioning functions and observe whether it:
- Travels smoothly without abnormal drag or vibration.
- Rotates into intended positions without drift.
- Locks and remains stable when positioned.
- Appears centered and square to the selected receptor when using normal detents or alignment positions.
- Shows no external sign of collision-related displacement.
Do not attempt mechanical tube suspension adjustments or internal calibration.
Expected outcome: The tube head positions normally, remains stable, and appears properly oriented to the intended receptor.
If the tube head will not remain positioned, appears physically misaligned, or has abnormal movement: Remove the system from service and escalate for repair.
10. Perform Authorized Collimation or Alignment Verification Only When Appropriate
If no obvious external cause is found and your Clinical Engineering department is authorized and equipped to perform radiographic quality-control checks, complete the approved light field-to-radiation field and centering verification procedure using proper radiation safety controls and test tools.
Do not use a patient for verification. Do not make collimator or tube alignment adjustments unless specifically trained, authorized, and working from approved service documentation.
Philips lists collimator functionality and fixation checks as annual planned-maintenance tasks and collimator component integrity checks every three years; planned maintenance is intended for qualified and authorized personnel.
Expected outcome: The light field, radiation field, and receptor alignment meet the facility’s approved quality-control acceptance criteria.
If verification fails or cannot be safely completed: Remove the system from service and escalate for authorized service evaluation.
If the Problem Persists
If the collimator light field remains abnormal, blade movement is unreliable, or tube-to-receptor alignment cannot be verified after external checks, common setup and external causes have been ruled out. The issue may involve the collimator assembly, light field system, positioning hardware, calibration, fixation, or internal control components.
The device should be:
- Removed from service.
- Labeled Out of Service.
- Sent for repair or qualified bench/service evaluation.
- Returned to clinical use only after appropriate alignment, collimation, image-quality, and safety verification.
Knowing when to stop is proper troubleshooting. A radiographic system with uncertain beam limitation or alignment should not be used clinically.
Clinical Use Tip
Never evaluate a suspected collimation or tube alignment problem during an active patient examination. Move imaging to an alternate room first, and perform verification only under approved radiation safety and quality-control procedures.
Work Order Documentation (CCR Method)
CCR = Complaint, Cause, Resolution
Complaint
What was reported by the clinical staff.
Example:
"Imaging staff reported that the DigitalDiagnost C90 collimator light field appeared off-center and the field blades did not close evenly during table exams."
Cause
What was observed during troubleshooting.
Example:
"External inspection found no obstruction or visible damage, but the light field remained asymmetric and blade response was inconsistent during non-patient functional testing."
Resolution
What action was taken.
Example:
"Removed the radiographic room from service, labeled the system Out of Service, and escalated to authorized service for collimator and tube alignment evaluation before clinical reuse."
Helpful Details to Include (If Known)
- Exact reported symptom: no light, dim light, blade movement problem, or alignment concern.
- Table, wall stand, or all imaging positions affected.
- Specific protocol or receptor selection involved.
- Any displayed fault or warning messages.
- Light field appearance and repeatability.
- Blade response during open/close commands.
- Tube head movement, locking, or drift observations.
- Evidence of impact, collision, loose covers, or obstruction.
- Whether authorized quality-control verification was performed.
- Final device status: returned to service or removed from service.
Final Thought
A collimation or tube alignment concern should be approached systematically: protect the patient, verify the complaint, rule out external and setup-related causes, and escalate when accurate beam limitation cannot be confirmed. Clear CCR documentation supports patient safety and efficient repair follow-up.
That is successful troubleshooting.