1. Principles of Radiology
Daniel Podd RPA-C

2. Physics of Radiology
X-Rays produced by electron beam hitting tungsten film target
Electrons strike film, metallic silver is precipitated if no obstruction to beam, resulting in bright film
Obstruction in path of beam prevents silver precipitation; film remains dark
The negative of this film is known as the Plain X-Ray, or radiograph

3. Positive Negative (Developed)
Radiograph, “Plain Film”

4. Radiodensity as a Function of Thickness

5. Radiodensity as a Function of Composition with Thickness Kept Constant

6. X-Ray
A-D:
Radiolucent or Radioopaque?
Why?

9. AP CHEST: Patient Position
                             
                                
AP CHEST: Patient Position

10. AP CHEST

11. PA CHEST: Patient Position
                              
                                
PA CHEST: Patient Position

13. L: Lung
R: Rib
T: Trachea 
AK: Aortic knob
A: Ascending aorta
H: Heart  
V: Vertebra
P: Pulmonary artery
S: Spleen

14. Lateral

15.                                  
Bullet + PA only = ?

16.                                  
Bullet + PA & Lateral =

17. PA Chest
Lordotic View

18. Fluoroscopy
Mechanism: Continuous below patient, amp- lified by intensifier above patient; broadcast on high-resolution television screen
Provides live animation
Imaging reversed vs xray
Uses: Barium swallow to
X-ray beams from
evaluate esophagus,
small and large intestines, vessel catheter guidance

19. Fluoroscopy Spot Film: Single X-ray during procedure.
Film developed into negative

20. Angiography systems Most approaches via femoral artery or vein
Mechanism: Uses X-rays and intravascular injection of iodinated contrast to evaluate arterial (arteriogram) and venous (venogram)
systems
Vasoocclusive
disease
Most approaches
via femoral artery
or vein

21. Computerized Axial Tomography
Cross-sectional slice radiographs of the body using thin beam of X-rays through desired axial plane
Slices up to 1.0 mm that represent density values; no superimposed images
Viewed as if facing patient and looking up through feet
Density Less Dense: Air, Fat (black)
More Dense: Bone (white)

22. CT Scan

23. CT Scan Angiography 3DCT, 3-Dimensional CT scan
Injection of IV contrast to enhance vascular system
Useful for aortic aneurysms, coronary heart disease, carotid vascular occlusive disease

24. CT Scan Angiography

25. Ultrasound
Mechanism: High-frequency sound waves beamed directed into body, onto organs and their interfaces; transducer receives and interprets reflection of these beams from organs
Acoustic Impedance: beam absorption by tissues, based on density and velocity of sound through different adjoining tissue types

26. Ultrasound
Image (echo) produced when different neighboring tissues reflect different acoustic impedances
Solid organs, fat, & stones: Echogenic (white)
Fluid & cysts: Anechoic (black)

27. Ultrasound

28. Ultrasound Advantages No ionizing radiation Applicable to any plane
Cost-effective
Portable
Real-time imaging
Disadvantages
1. Time consuming
2. Poorer quality

29. Magnetic Resonance Imaging (MRI)
Mechanism: Patient placed in magnet tunnel; radio waves passed through body in pulses. Pulses returned from tissues, transformed into 2D image based on relaxing times: T1 & T2 T1 T2
High Signal (brightness) Low Signal
fat, medullary bone
blood (gray), solid mass, cysts, air, compact bone
tumors, solid masses, CSF, cysts
compact bone, blood, fat, air

30. MRI Advantages vs CT: Multiplanar scanning
Better soft-tissue differentiation
3. Contrast-free 3DMR
Contraindications:
Metals, clips, pacemakers

31. MRI T1 T2

32. Normal
CXR

33. Normal
CXR

34. Enlarged
Hila

35. Aortic Knob
Hilar Mass
(Left)

36. Right vs Left Pulmonary Artery

37. Kerley B-Lines
Fine horizontal opacified lines representing pulmonary edema
Seen in CHF, pulmonary fibrosis, heavy metal fibrosis, malignancy

38. Blunted Costophrenic Angle

39. Lung Mass: Cavitation

40. Lung Mass: Solid Tissue

41. Air Space (Alveolar) Disease

42. Interstitial Disease

43. Alveolar or Interstitial?

44. Alveolar or Interstitial?

45. Alveolar or Interstitial?

46. Lobar Consolidation: Right
Think anatomically
3 Lobes
RLL located Lateral to heart, but anterior to diaphragm
Obliteration of right CoPhS
Right heart border intact
RUL and RML located
Anterior to heart
Obliteration of
mediastinum and cardiac
borders
Right CoPhS intact

50. Lobar Consolidation: Left
LUL lies anterior to heart and superior to diaphragm (and LLL)
Obliteration of left heart border only
Left hemidiaphragm intact
LLL located lateral to heart and anterior to diaphragm
Obliteration of left hemidiaphragm
Left heart border intact

53. Where Is This Consolidation?

54. Diaphragm
Gastric Bubble

55. Diaphragm: Expiration vs Inspiration

56. Pleura
Anatomically, the visceral and parietal pleura are separated by a potential space, the pleural space
Fluid in this space is known as a Pleural Effusion
Effusions may be large or small, but settle to base of lung due to gravity
Completely obscures aerated lung and heart/mediastinum/diaphragm borders

57. Pleural Effusion: Large

58. Pleural Effusion: Small

59. Pleural Effusion: Small (special case)

60. Pleural Effusion: Small (special case)

61. Pneumothorax
Introduction of air into the normal vacuum of pleural space
Radiographic findings:
1. Hyperlucent versus aerated lung 2. Passive atelectasis of ipsilateral lung
3. Depression of ipsilateral hemidiaphragm
4. Mediastinal shift

62. Pneumothorax Optimal Radiographic Images: Expiration film
2. Lateral decubitus film

63. Pneumothorax

65. Subtle Pneumothorax

66. Pulmonary Embolism Lung vessel embolus Radiologic findings:
1. Diminished lung volume
Elevated ipsilateral hemidiaphragm
Linear/patchy ipsilateral atelectasis
2. Completely Normal ! (m/c)
CXR to rule out other etiologies

67. Pulmonary Embolism

68. Pulmonary Embolism
With Infarction:
1. Hampton’s Hump

69. Pulmonary Embolism Further Diagnostics Perfusion Test (Q)
Technetium-99
Ventilation Test (V)
Xenon gas
Perfusion/Ventilation mismatch, “V/Q Mismatch”

70. Pulmonary Embolism V/Q Scan Interpretation
Normal Perfusion scan =Rules out PE
Negative/Low Probability scan (slight perfusion abnormality or V/Q matching)= Non-embolic pulmonary abnormalities
Positive/High Probability= V/Q mismatch
Intermediate/Indeterminate = Low & High
Pulmonary Angiogram indicated for 3, 4, or 2 with strong clinical evidence

71. Pulmonary Angiogram
Gold Standard

72. Helical (Spiral) CT Scan
Indicated for suspected PE with abnormal CXR
CT venogram: Adding IV contrast for concurrent deep leg vein scan

73. References

74. References

75. References http://brighamrad.harvard.edu/Cases/bwh/images/84/R54A2.GIF