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Quality Control

Quality Control. Rad T 110. Aim :. The purpose of QC to achieve high quality images with the least amount of radiation. Quality Control is a part of Quality Assurance program. Test Types:. Acceptance test Monitoring test Annual Test After repair or tube replacement. Acceptance Test:.

stephanie-ellison
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Quality Control

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  1. Quality Control Rad T 110

  2. Aim : • The purpose of QC to achieve high quality images with the least amount of radiation. • Quality Control is a part of Quality Assurance program

  3. Test Types: • Acceptance test • Monitoring test • Annual Test • After repair or tube replacement

  4. Acceptance Test: • Performed upon newly installed equipment to verify purchase specification and to establish performance base line. • Frequency: • To be performed once only when new machine is installed

  5. Monitoring Test: • Performed for vital parameter on routine basis. • Frequency: • Every 2-3 months

  6. Annual Test: • Performed for vital parameter • Frequency: • once a year

  7. Parameters to be checked • Beam Alignment and Collimator Accuracy • Radiation output and linearity of mR/mAs versus kV(Large and small FS • Assessment of Total Beam Filtration (HVL) • Assessment of Focal Spot size • Accuracy and constancy of Exposure Timer • Measuring of Scattered Radiation (using Water Phantom) • Leakage Radiation from X-Ray tube 1-5 Monitoring test, 2- Annual Test

  8. Parameters to be checked 1. Beam Alignment and Collimator Accuracy Small hole Beam Alignment Test Tool

  9. Parameters to be checked 1. Beam Alignment and Collimator Accuracy X-ray Tube Radiation beam Light beam Test Tool

  10. 1. Beam Alignment and Collimator Accuracy Improper central ray alignment will distort a radiographic image. When used with the Collimator Test Tool, this device provides a simple means of determining if the X-ray beam is perpendicular to the image receptor and centered with respect to the light field.

  11. 1. Beam Alignment and Collimator Accuracy

  12. Parameters to be checked 2. Constancy of Radiation output and linearity of mR/mAs versus kV2 (Small & Large focus) Victoreen Kv Meter Displays kVp maximum, kVp average, kVp effective, dose and time

  13. Parameters to be checked • Constancy of Radiation output and linearity of mR/mAs versus kV2 (Small & Large focus) Set mAs=20 for LF & 10 for SF X-ray Tube Radiation beam Measure kVp & Output Table top

  14. Radiation output and linearity of mR/mAs versus kV • The mR/mAs relationship must be linear and acceptable • kVp measured by the kV Meter must be within the acceptable range ( i.e. + 10% of kVp indicated by machine) • The exposure dose (Output) must be within acceptable limits .

  15. Parameters to be checked 3. Assessment of Total Beam Filtration / (HVL) HVL(Half Value Layer): is the most frequently used factor for describing both the penetrating ability and the penetration through specific objects. Defined: thickness of material penetrated by one half of the radiation Unit: mm or cm Filtration: attenuation of photon according to their Energy ( simply the ability to get rid of unnecessary radiation)

  16. Parameters to be checked 3. Assessment of Total Beam Filtration (HVL)

  17. Parameters to be checked 3. Assessment of Total Beam Filtration (HVL) X-ray Tube Put Aluminum Shield with different thickness 1,2,3,4 mm Measure Output only Table top

  18. Parameters to be checked 3. Assessment of Total Beam Filtration (HVL) HVL=3.0 mm (acceptable limit > 2.5 mm Al)

  19. Parameters to be checked 4. Assessment of Focal Spot size Focal Spot area: is the surface area of the anode that is bombarded by electron beam. For Radiography units from 0.6 to 2.0 mm For Mammo units 0.3 –to 0.6

  20. Parameters to be checked 4. Assessment of Focal Spot size Fine Parallel line Focal Spot Test Tool

  21. Parameters to be checked 4. Assessment of Focal Spot size Focal Spot Area( level) X-ray Tube Test Tool 60 cm from the tube Low Speed film Couch

  22. Parameters to be checked 4. Assessment of Focal Spot size • A small focal spot size is used to obtain x-ray image with minimum blur. • Small focal spot tend to concentrates heat and gives load on focal spot area. • If the quantity of heat delivered during an individual exposure exceeds the track capacity, the anode surface can melt.

  23. Parameters to be checked 4. Assessment of Focal Spot size • so … it is necessary to measure the focal spot size and compare it with the original focal spot size with the machine. • Focal spot size of any machine is written on the top of X-ray Tube.

  24. Parameters to be checked 4. Assessment of Focal Spot size

  25. Parameters to be checked 5. Accuracy and constancy of Exposure Timer X-ray Tube Measure the time compare it with time of exposure from the machine Table top

  26. Parameters to be checked 6. Measuring of Scattered Radiation (using Water Phantom) • When x-ray beam or gamma radiation passes through an object it can either • Penetrate the object without interacting • It can interact with matter and be completely absorbed. • It can interact and scattered or deflected from original direction.

  27. Parameters to be checked 6. Measuring of Scattered Radiation (using Water Phantom) X-ray Chest Bucky X-ray Tube Water or Chest Phantom Ionization chamber Ionization Chamber 1 m from center

  28. Parameters to be checked 7. Leakage Radiation from X-Ray tube • Rarely done. • Typically for very old units. • To test if there is any leakage of radiation from the x-ray tube.

  29. Parameters to be checked Fluoroscopic Unhappiness and spatial Resolution • The test pattern should be placed on the input window of the II and oriented so that the bar patterns are imaged perpendicular to the raster lines of the monitor display.

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