Digital Display Device QA/QC Notes

Quality Assurance (QA) Program

  • Deals with patient services, focusing on the patient's experience from start to finish.

Continuous Quality Improvement (CQI)

  • Improves processes within which employees function as a team for patient care.
  • Requires involvement of all employees.

The Joint Commission (TJC)

  • Ensures high-quality services and care.
  • Requires QA/QC programs.

Quality Control (QC)

  • Product-oriented, focusing on defect identification.
  • Reactive approach using corrective tools.
  • Specific team responsibility.
  • Monitors radiology instrumentation, equipment, and artifacts.
  • Ensures safe radiographic procedures and high-quality images.
  • Equipment must be tested before use.
  • Required by law to maintain room/department license.

Process of a QC Program

  • Acceptance testing.
  • Performance monitoring.
  • Error maintenance.
  • Annual evaluations are required.

Acceptance Testing

  • Performed before machine installation or major repairs.
  • Determines if equipment is working properly.

Performance Maintenance (PM)

  • Tests performed daily, monthly, quarterly, and annually to assure proper equipment function.

Error Maintenance

  • Occurs due to poor equipment performance.
  • Requires corrective action.

QC Documentation

  • Consistent and accurate records are important.
  • Unacceptable results must be documented with an action plan.

Physicist’s Annual Testing

  • Includes noise, spatial resolution, contrast resolution, dose response/signal dynamic range, detector calibration, dose calibration, AEC testing, kVp calibration, plate reader calibration, residual signal erase, image artifacts, repeat analysis, uniformity test, beam filtration, collimation, monitor display function, luminance & reflection testing.

Workstations

  • Require regular QC testing.
  • Radiologist’s viewing stations are higher quality.
  • Assessment for Display Performance for Medical Imaging Systems is completed by physicists and technologists for tests.

SMPTE Test

  • Used to determine if contrast/brightness settings on monitor are acceptable.
  • Observes 5% and 95% luminance patches.

Workstation Calibration – AAPM TG 18 Test

  • Commonly called TG18-QC.
  • Provides overall assessment of a monitor’s adjustment & calibration.

Photometer

  • Measures light intensity (luminescence) on a workstation monitor.

Elements of a QC Program for Radiographic Systems

  • Filtration, collimation, focal spot size, spatial resolution, PSP Imaging Plate Uniformity Test, PSP Imaging Plate Erasure Thoroughness, kVp calibration, exposure timer accuracy, exposure linearity, exposure reproducibility.

Filtration

  • State requires minimum total filtration of 2.5 mm Al.
  • Measured by checking HVL.
  • Checked annually or when tube/housing is changed.

Collimation/Beam Restriction Test

  • Checks beam alignment.
  • Most systems have PBL collimators.

Focal Spot

  • Important for image quality.
  • Small focal spot is used when spatial resolution is needed.
  • Large focal spot is used when a short exposure time is priority plus more photons emitted.

Spatial Resolution

  • Ability to render small objects on an image.
  • Smaller pixel size = better spatial resolution.

PSP Uniformity Test

  • Assesses uniformity of signal from exposed IP.
  • Assists in detecting artifacts.
  • Cassettes/IP must be cleaned regularly.

PSP Imaging Plate Erasure Thoroughness

  • Ensures minimal residual signal (ghosting).
  • White light is used to delete trapped energy from IP.

AEC

  • Sets exposure factors to ensure a quality radiographic image.

Exposure Timer Accuracy

Exposure Linearity

  • Ability of x-ray unit to produce constant radiation output for various mA and time combinations.

Exposure Reproducibility

  • Tests kVp, mA, and time in successive exposures.

Protective Apparel Test

  • Aprons, gonadal shields, gloves checked for defects under fluoroscopy.

Recognition & Reporting Malfunctions

  • Technologist's responsibility to report malfunctions.
  • Equipment failure must be repaired and recalibrated by a physicist.

Fluoro QC

  • Fluoro exams = high pt. dose.
  • Entrance skin exposure (ESE) averages 3 to 5 rads/min.

Exposure Rate

  • State law: ESE shall not exceed 10R/min for normal fluoro.
  • ESE allowed up to 20R/min for interventional procedures.