1. Chapter 10 Clinical Application of the Chest Radiograph

2. Learning Objectives After reading this chapter you will be able to:
Describe how a chest radiograph is produced
Define terms radiolucent and radiopaque
Identify the four densities seen on a chest radiograph
Explain how the relationship between the x-ray source and the patient affects the images viewed on the radiograph

3. Learning Objectives (cont’d)
State standard distance between x-ray source and film for posteroanterior chest film
Identify clinical indications for a chest x-ray
Explain the technique, indications, and advantages and disadvantages of the following chest radiographic views: posteroanterior, left lateral, anteroposterior, lateral decubitus, apical lordotic, oblique, expiratory

4. Learning Objectives (cont’d)
Describe correct position for endotracheal tube placement as seen on a chest x-ray
Identify the value in assessing a chest radiograph in the following situations:
Central venous pressure line insertion
Pulmonary artery catheter placement
Nasogastric tube placement
Chest tube insertion
Thoracentesis
Pericardiocentesis
Bronchoscopy

5. Learning Objectives (cont’d)
Explain the technique, indications, and advantages and disadvantages for computed tomography (CT) scanning
Discuss the use and indications for magnetic resonance imaging in lung disease

6. Learning Objectives (cont’d)
Explain the technique and indications for performing nuclear medicine lung scans
Describe how these problems affect lung scans: thromboembolism, atelectasis, pneumonia, emphysema
Describe proper technique to assess the following to evaluate chest x-ray: depth of inspiration, placement on view box, adequacy of exposure, patient rotation

7. Learning Objectives (cont’d)
Explain the technique and indications for the use of pulmonary angiography
Know proper technique for performing a systematic descriptive evaluation (interpretation) of a chest x-ray
Explain the significance of these special radiographic evaluation signs: silhouette sign, air bronchogram

8. Learning Objectives (cont’d)
Discuss limitations of a chest radiograph
Appraise clinical and chest radiographic findings for the following lung disorders:
Atelectasis
Pneumothorax
Hyperinflation
Interstitial lung disease
Congestive heart failure
Pleural effusion
Consolidation
Pneumonia

9. Overview Physics related to radiographs Standard and special views
Techniques for interpreting the chest film
Common pathologic abnormalities seen on chest x-ray films

10. Production of the Radiograph
X-rays:
Electromagnetic waves that radiate from a tube that an electric current has passed through
Tube made of a cathode attached to low-voltage electron source (transformer)
End of cathode wire is inside the vacuum-sealed tube
As electrons flow through the wire they strike the anode

12. Indications for CXR Examination
Detecting alterations of the lung caused by pathologic processes
Determining the appropriate therapy
Evaluating the effectiveness of treatment
Determining the position of tubes and catheters
Observing the progression of lung disease

13. Radiographic Views Standard views Special views Posteroanterior
Anteroposterior
Special views
Lateral decubitus
Apical lordotic
Oblique
Expiratory

14. Anteroposterior View Portable chest film
Film cassette placed behind patient’s back
X-ray beam moves from front to back (anterior to posterior) 4 feet from beam’s origin
More magnification artifact than PA chest x-ray

15. Anteroposterior View (cont’d)
Indications for AP portable films
Evaluate the lung status
Evaluate lines and tubes
See results of invasive therapeutic maneuvers

16. Postprocedural CXR Evaluation
Tracheal intubation
Thin radiopaque strip along entire length of ETT
Inferior tip of ETT 3 to 5 cm above the carina
Accidental placement in right mainstem or esophagus must be recognized
Reposition
Secure
Follow-up CXR

19. Postprocedural CXR Evaluation (cont’d)
Central venous pressure (CVP)
Placed in R or L subclavian vein or jugular vein
Tip just above confluence of SVC and RA
Accidental lung puncture must be recognized
AP chest film required before initiating fluid therapy

23. Postprocedural CXR Evaluation (cont’d)
Pulmonary artery catheter
Tip at the right midlung near the hilum
Catheter is sutured into place if chest film demonstrates proper position of catheter tip
Accidental rupture of inflatable balloon may rupture pulmonary artery
Area of pulmonary infarction on CXR

25. Postprocedural CXR Evaluation (cont’d)
Nasogastric feeding tubes
Ensure tip placed at the stomach or small bowel
Chest films to recognize misplacement
Into the trachea
Into mainstem bronchus
Deep into the lung

26. Postprocedural CXR Evaluation (cont’d)
Chest tubes
To drain excess air, blood, or pleural fluid from the pleural cavity
Tip of the tube should be posterior and near the apex of lung so drainage can occur
Periodic portable CXRs to ensure tube’s correct position

28. Procedures Requiring Evaluation with an AP Portable Film
Thoracentesis
Pericardiocentesis
Bronchoscopy
After transtracheal biopsy or needle aspiration

29. Computed Tomography Mathematical modeling of tissues Standard CT
Electron beams pass through tissue
Slice of body equivalent to a slice of bread
Standard CT
High-resolution CT

30. Computed Tomography (cont’d)
Lung tumors
Differentiate lymph nodes or tumor
As small as 2 to 3 mm
Chronic interstitial disease
Superior to conventional CXR
AIDS
Early detection of pneumonias, abscesses, and cavities

32. Computed Tomography (cont’d)
Occupational lung disease
Parenchymal and pleural changes
Pleural plaques in asbestosis
Pneumonia
Cost has restricted its use for pneumonias
Bronchiectasis
COPD
Remarkable clarity and detail

33. Magnetic Resonance Imaging
Superior to CT scan in:
Evaluating of mediastinal and hilar masses
Differentiating lymph node enlargement from enlarged blood vessels
Evaluating chest wall invasion by lung cancer

35. Radionuclide Lung Scanning
Gamma radiation emitted from the chest after radiopharmaceuticals injected into the bloodstream and inhaled into the lung
Evaluation of suspected pulmonary embolism
Normal ventilation and abnormal perfusion
Pneumonia and atelectasis
Poor ventilation and perfusion

37. Positron Emission Tomography
Also called PET scan
Determines metabolic activity of tissues
Tumors and areas of infection have high metabolic activity = hot spots
Evaluation of local and distant metastasis

39. Pulmonary Angiography
To evaluate thromboembolic disease of the lungs
Performed after V/Q lung scanning is nondiagnostic
Injection of contrast medium into pulmonary artery
CT angiography has reduced frequency of conventional angiography

42. Evaluation of the Chest Radiograph
Recognition of anatomic landmarks
Review clinical findings before viewing CXR
Placing the chest film
Patient facing clinician
Cardiac shadow more prominent on the left side

44. Determine Quality of the Film
Visualize vertebral bodies through cardiac shadow
If easily seen: overexposed; recognize rotation of the patient
Spinous processes to medial ends of clavicles
Degree of patient’s inspiratory effort
10 posterior ribs on PA film

46. Interpretation
X-ray penetration inversely proportional to density of structure
Normal lung tissue has low density
Cavities, blebs (darker)
Consolidation increases density
Pneumonia, tumor, collapse (white patch)
Greatest density in the chest: bones
Systematic review of all structures
A through Z

47. Silhouette Sign and Air Bronchogram
Infiltrate that obliterates heart border or diaphragm must be located in anterior segments of the lung
Air bronchogram
Visible bronchi when surrounded by consolidated alveoli
Confirms intrapulmonary disease

49. Limitations of the Chest Radiograph
Small lesions may not be seen
Often normal in patients with significant respiratory symptoms
Asthma

50. Clinical and Radiographic Findings in Lung Diseases
Atelectasis
Hyperinflation
Interstitial lung disease
Congestive heart failure (CHF)
Pleural effusion
Consolidation

51. Atelectasis Compressive atelectasis Obstructive atelectasis
Pleural effusion, pneumothorax, hemothorax
If severe: mediastinal shift
Obstructive atelectasis
Tumor, aspirated foreign body, mucus plugging
Postoperative atelectasis
Microatelectasis
CXR: lung volume loss, mediastinal shift

53. Pneumothorax Often causes atelectasis Tension pneumothorax
Mediastinal shift
Tracheal deviation away from involved side
Pleural line

56. Hyperinflation Obstructive lung disease
Increased AP diameter
Large restrosternal air space
Flattening of diaphragm
CXR neither sensitive nor specific for COPD
Provides supporting evidence

58. Interstitial Lung Disease
Substance activates patient’s immune system = scar or fibrosis
Months to years
Sarcoidosis
Large hilar and paratracheal lymph nodes
Asbestosis
Calcified pleural or diaphragmatic nodules

59. Interstitial Lung Disease (cont’d)
End-stage pulmonary fibrosis
Honeycomb-size cavities
Bronchiectasis
Large air bronchograms with thick walls

64. Congestive Heart Failure
Redistribution of pulmonary vasculature
Engorgement of upper lobe vessels
Fluid collection in dependent portions of the lungs
Increased cardiothoracic (C/T) ratio (>0.5)

65. Congestive Heart Failure (cont’d)
Kerley’s B lines
Right base, <1 mm thick, 1 to 2 cm long, horizontal
Miscellaneous signs
Increased interstitial markings, pleural effusion

67. Pleural Effusion Usually >100 ml of fluid Small volume effusion:
Blunting of the costophrenic (CP) angle
Small meniscus sign
Partially obscured and elevated diaphragm
Large volume effusion
Complete or nearly complete whiteout
Complete obscuring of the hemidiaphragm
Confirm with lateral decubitus

70. Consolidation Minimal volume loss Lobar or segmental distribution
Homogeneous density
Air bronchograms
See Figures and 10-18

71. Summary
Dense body tissue appears white on CXR (radiopaque); air-filled body tissue appears black (radiolucent)
Increasing ventilator pressures may indicate a pneumothorax and should prompt an order for a CXR
CT scans show structural information using x-rays, but provide more detail and more specific information about densities 71

72. Summary (cont’d)
MRI uses a strong magnetic field rather than x-rays to provide images of the body
V/Q lung scans helpful only if normal or highly suggestive for pulmonary emboli
PET scan uses radioactively tagged sugar water injection to demonstrate metabolically active tissue

73. Summary (cont’d) CXR interpretation requires evaluation of:
Proper placement of the film on the view box
Proper film exposure
Proper patient rotation and lordosis
Systematic review of structures 73

74. Summary (cont’d)
Silhouette sign allows one to know whether a pulmonary opacity is touching the heart or diaphragm rather than residing in lung tissue anterior or posterior to those tissues
Air bronchograms suggest fluid in the lung tissue surrounding patent airways