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.

33. MONITOR ISSUES: QUESTIONS ASKED
CRT vs. LCD LCD
How many Mpx 5
What about the contrast ratio? 250+
How many bits 8,10, or 16? 9-10
Monochrome LCD or color LCD? Color
Courtesy of E. Samei 56

34. Consumer grade or medical grade display Medical
What about PDAs? Do NOT Use
What about ambient conditions Modest
Do displays need testing? Yes

35. Luminance
Viewboxes
• Low intensity:
– nits (cd/m2)
• High intensity:
– nits (cd/m2)
• Mammo:
– nits (cd/m2)
Monitors
~ nits (cd/m2)

36. LCD VS CRT DISPLAYS
Barco

37. Monitor QC
• Luminance calibration􀃎 Photometer
• Focus (sharpness) 􀃎 test patterns
• Test Patterns
– SMPTE (Society of Motion Picture & Television
Engineers)
– AAPM TG18

38. Materials Required:
Hardware:
densitometer “puck” for correct monitor (CRT, LCD, BW, Color)
USB expander
memory stick
Software: testing software compatible to CPU operating system (e.g.Win XP), and to manufacturers software

39. Viewing Conditions Illuminance Direct Sunlight = 105 lux
Overcast = 103 lux
Twilight = 101 lux
Moonlight = 10-1 lux
Office = lux
Reading room = lux
• Ambient Light
– Reflected
• specular & diffuse
– Decreases image contrast
– Anti-reflective coating
• Reduces luminance
– CRT worse than LCD

40. Monitor Testing
The acquisition workstation and secondary displays should be tested frequently using a standard image test pattern.
The SMPTE RP-133 (Society of Motion Picture and Television Engineers) or AAPM TG-18 QC test patterns are suitable.

41. Using the SMPTE Test Pattern
There should be no blurring or bleeding of bright display areas into dark areas or aliasing of the spatial imaging patterns.
All monitors used for interpretation should be tested at least monthly

42. Using the SMPTE Test Pattern
For the dynamic range test, both the 5% and 95% contrast areas should be visible and distinctly different than the adjacent 0% and 100% areas.
Therefore:

43. Spatial Resolution & Aliasing
The spatial resolution (linearity) and aliasing (distortion) of the monitor are within acceptable limits if the high contrast bar patterns in the test image are distinct as simple black and white pairs.