18 Questions
Which factor is responsible for the blurring at the edges of a radiographic image?
Movement
What does MPI stand for in the context of non-destructive examinations?
Magnetic Particle Inspection
What does f.f.d. stand for in relation to gamma source?
Focal Film Distance
What is the smallest distance between recognizable images on a film or screen called?
Image Resolution
What contributes to image blurring in radiographic images?
Penumbra or movement
What type of radiation results from the loss of energy or charged particles?
Electromagnetic Radiation
What is an example of a standard I.Q.I. used for radiographic inspection of aircraft structures?
Step-wedge I.Q.I.
Which type of I.Q.I. is sensitive to both sharpness and contrast, especially in smaller sizes?
Wire I.Q.I.
What is the main purpose of using an I.Q.I. for radiographic inspection?
To check for image sharpness and contrast
Which factor influences the sharpness of a radiographic image, especially under the control of the radiographer?
Film characteristics
In what scenarios would variations of standard I.Q.I. be used?
When searching for fatigue cracks
What does the wire I.Q.I. contain that helps assess image sharpness and contrast?
Thin metal wires
What may assist in identifying an area under examination?
Isometric drawing
Why might it be necessary to expose two or three films simultaneously without wrapping in a common cassette?
To improve the quality of radiographs for different thicknesses
When are gamma sources occasionally used in aircraft radiology?
When X-ray equipment is not available
How can a lead screen be helpful in radiography?
Achieving satisfactory radiographs of different thicknesses
What is the primary reason for using X-ray sets over gamma sources in aircraft radiology?
Because of unsharpness and lack of contrast with gamma sources
Why might simultaneous exposure of two or three films be employed without intervening wrapping in a common cassette?
To clearly show different thicknesses on radiographs
Study Notes
IQI in Radiographic Inspection
- IQI (Image Quality Indicator) is essential for thick specimens, but aircraft structures can serve as a natural IQI for most radiographic needs.
- There are different types of IQI, including step-wedge IQI and wire IQI.
Step-Wedge IQI
- Consists of a number of steps ranging in thickness from 0.005 in to 0.1 in or greater as required.
- Each step contains holes of varying sizes, used for identification and image sharpness.
Wire IQI
- Consists of short lengths of wire in graduated diameters, embedded in thin rubber or plastic sheet.
- Sensitive to sharpness and contrast, particularly in smaller sizes.
Specialized IQI
- Variations of standard IQI can be used for special purposes, such as searching for fatigue cracks.
Geometric Considerations
- Sharpness of radiographic image is influenced by film characteristics and geometric effects, which are under the control of the radiographer.
Radiographic Techniques
- Simultaneous exposure of two or three films can be used to capture a range of thicknesses.
- Lead screen separating two films can be used to achieve satisfactory radiographs of different material thicknesses.
Gamma Rays in Aircraft Radiology
- Gamma sources are used when X-ray equipment cannot access the inspection area.
- Gamma sources have limitations, including unsharpness, lack of contrast, and decreased radiated energy.
Radiology Terms
- Atom: an atom of a particular element with the same chemical properties and atomic number but a different mass number.
- Blurring: edge distortion of a radiographic image due to the radiation source being of finite dimensions.
- Penetrating power: the ability of a beam of radiation to pass through a material.
- Radiographic image: the photographic image produced by a beam of radiation after passing through a material.
- Resolution: the smallest distance between recognisable images on a film or screen.
- Focus-to-film distance (FFD): the distance from the source of primary radiation to a film set up for exposure.
- Tube current: the current passing between the cathode and anode during X-ray tube operation.
- X-ray shield: a type of shield that, in addition to the X-ray tube, may contain part of the high voltage generator.
- Image blurring causes: penumbra, movement, grain size, or light, electron or X-ray scatter.
- Electromagnetic radiation: radiation resulting from the loss of energy or charged particles (e.g., electrons).
Learn about the use of Image Quality Indicators (I.Q.I) in aircraft radiography, including step-wedge I.Q.I. Explore how different components of aircraft structures serve as I.Q.I for radiographic needs.
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