Mind Map

Outline
and
Learning Guide

Objectives
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Learning Activities

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Class Discussion

Self-study
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1. Describe how visibility of detail (small objects and structures) is reduced and limited by the amount of blurring in any imaging process.  Give some everyday (non-radiography) examples of where you observe this.

2. Identify the three possible sources of blurring in radiography that can limit visibility of detail.

3. Draw a simple diagram of a radiographic setup including the: 1. focal spot, 2. receptor, and 3. a small object to be imaged.

4. On the diagram from above, mark and label the following distances: FRD, ORD, OFD.

5. For a FRD of 100cm and a 1.5cm object located 20cm above the receptor, Calculate:
   1. The magnification factor.
   2. The size of the image of the object
   3. The position of the object on the S scale.

6. If an object in the body is moving at a velocity of 1.2 cm/sec because of respiration, calculate the amount of blurring that would occur with an exposure time of 0.25 sec.

7. Describe two actions to reduce motion blurring in radiography.

8. Use an object (such as your hand) to cast a shadow from a light and demonstrate the principle of focal spot blurring.

9. Use your hand, as described above, to show the relationship between (focal spot) blurring and distance between your hand (the object) and the shadow surface (the receptor).

10. Identify the two factors that determine the amount of focal spot blurring during a radiographic procedure.

11. For a 100cm FRD and an object located 20cm from the receptor, calculate the amount of blurring (at the location of the object) produced by a 0.6mm focal spot.

12. Describe the range of focal spot sizes use in clinical radiography.

13. Explain the advantage of larger focal spot sizes.

14. Explain the advantage of using smaller focal spot sizes.

15. Describe how focal spot size is measured using a star test pattern.

16. Describe how focal spot size is measured using a pinhole camera.

17. Describe the principle sources of blurring that can occur in a film/intensifying screen receptor.

18. Describe and illustrate the relationship between blurring within an intensifying screen and receptor sensitivity (speed) and the effects on patient exposure.

19. Describe the general range of intensifying screens used in radiography with respect to their blurring characteristics and exposure requirements.

20. Describe the general sources of blurring within digital radiography receptors.

21. Briefly explain the effect of digital pixel size on blurring and image detail.

22. Describe and illustrate the relationship between digital image pixel size (blurring) and:
    1. The size of the digital image matrix
    2. The image size (field of view).

23. Describe the concept of how magnification reduces the effective receptor blurring (at the location of the object).

24. Describe the concept of composite (or combined) blurring from both the focal spot and receptor and how the amount of blurring depends on the location of the object.

25. Describe one or more clinical applications in which magnification is used to reduce blurring and improve image detail.

26.  Describe why focal spot size is a major concern and limiting factor when doing magnification.