2. Introduction to Radiographic Interpretation Special Emphasis on CXRs

3. Differential Absorption of X-rays
Dependent upon
Physical density
Atomic number
Thickness
Determine the gray scale of the radiograph
Absorb few x-rays = film black many x-rays = film white

4. Five Radiographic Opacities
Air Fat Soft tissue Bone Metal
least opaque to most opaque
most lucent to least lucent
Black to White

5. Radiographic Opacities & Contrasts
Air Air
Fat Mineral oil
Water Water
Bone Tums
Metal ???

6. Five Radiographic Opacities

7. Five Radiographic Opacities

8. Standard Radiographic Positions

9. Standard Radiographic Positions

10. Standard Radiographic Directions As seen when viewing
Dorsal
Proximal
Cranial
Cranial
Rostral
Dorsal
Right
Caudal
Palmar
Plantar
Left
Ventral
Distal
Caudal

11. Radiograph: two-dimensional image of a three-dimensional object
So What is it?
Lateral view
Cranial-caudal view

12. Radiograph: two-dimensional image of a three-dimensional object
So What is it?
Dorsoventral view

13. Interpretation Challenges
Magnification
Distortion
Image of a familiar object is unfamiliar
Loss of depth perception
Summation
Silhouette effect

14. Interpretation Challenges: Magnification
Enlargement of the radiographic image of an object relative to its actual size
Increased film-subject distance

15. Interpretation Challenges: Magnification

16. Interpretation Challenges: Magnification

17. Interpretation Challenges: Distortion
Distortion:Misrepresentation of the true shape of an object

18. Interpretation Challenges: Unfamiliar image of a familiar object

19. Interpretation Challenges: Depth perception

20. Interpretation Challenges: Summation
Superimposition of structures in different planes
Resultant image = summation of opacities

21. Interpretation Challenges: Summation

22. Interpretation Challenges: Silhouette Effect
Two structures of the same radiopacity in contact – their margins cannot be identified

23. Interpretation Challenges: Silhouette Effect

24. Interpretation Challenges: Silhouette Effect

25. CXR Interpretation Have a system!!
Method 1:
“Outside-to-inside”
Soft tissues
Bony framework
Lungs & hila
Diaphragm & pleura
Mediastinum & heart
Method 2:
“Are There Many Lung Lesions?”
Abdomen & diaphragm
Thorax
Lung (single)
Lungs (both)

26. CXR Interpretation Have a system!!
Method 1:
“Outside-to-inside”
Soft tissues
Bony framework
Lungs & hila
Diaphragm & pleura
Mediastinum & heart
Method 2:
“Are There Many Lung Lesions?”
Abdomen & diaphragm
Thorax
Lung (single)
Lungs (both) T L L M A

30. CXR Interpretation Beware the poor-quality film!!
Poor inspiration
High diaphragms, crowded lung markings
“Penetration”:
Disappearing thoracic vertebral details through the heart.
Rotation:
Note equal distances from the vertebral spines to the medial ends of the clavicles.

31. CXR Interpretation Beware the poor-quality film: Inspiration

32. CXR Interpretation Normal structures visible
Tracheal air column.
Carina.
First rib.
Peripheral lung fields have no markings except:
The minor fissure.
Top of the R diaphragm is usually between the anterior 6th & 7th ribs, and overlying the posterior 10th & 11th ribs.
Left diaphragm is lower (in 90-95%) by roughly half an interspace.
Inferior margins of the posterior ribs.
Anterior mediastinal line.
Superior vena cava.
Azygous vein.
Right descending pulmonary artery.
Pulmonary arteries and veins.
Right atrium.
Inferior vena cava.
Aortic arch.
Left pulmonary artery.
Border of the left ventricle.
Descending aorta.
Fat density lines in the intermuscular fascial layers

33. CXR Interpretation Normal structures visible
Costophrenic angle
Diaphragm
Heart
Aortic arch
Trachea
Hilum
Main carina
Stomach bubble
Ascending aorta

34. CXR Interpretation Normal structures visible
Costophrenic angle
Diaphragm
Heart
Aortic arch
Trachea
Hilum
Main carina
Stomach bubble
Ascending aorta

35. CXR Interpretation Normal structures visible
Tracheal air column.
Carina.
First rib.
Peripheral lung fields have no markings except:
The minor fissure.
Top of the R diaphragm is usually between the anterior 6th & 7th ribs, and overlying the posterior 10th & 11th ribs.
Left diaphragm is lower (in 90-95%) by roughly half an interspace.
Inferior margins of the posterior ribs.
Anterior mediastinal line.
Superior vena cava.
Azygous vein.
Right descending pulmonary artery.
Pulmonary arteries and veins.
Right atrium.
Inferior vena cava.
Aortic arch.
Left pulmonary artery.
Border of the left ventricle.
Descending aorta.
Fat density lines in the intermuscular fascial layers

36. CXR Interpretation PA vs. AP views

37. CXR Interpretation PA & Lateral views

38. CXR Interpretation Hyperexpansion = “Air Trapping”

39. CXR Interpretation “Big Lungs” & “Little Lungs”

40. CXR Interpretation Interstitial Infiltrates
Generalized interstitial thickening = linear (“reticular”).
Discrete interstitial thickening = nodules.
Interstitial & alveolar filling = silhouette.

41. CXR Interpretation Interstitial Infiltrates

43. CXR Interpretation Interstitial Infiltrates

45. CXR Interpretation Alveolar Infiltrates
Alveolar-filling, or “airspace” disease:
“Pointillist” patterns.
Air bronchograms.

46. CXR Interpretation Alveolar Infiltrates