ThePhysics and Physiology

of the Chest X-ray

Michael Aref, MD, PhDDepartment of Nuclear, Plasma, and Radiological

EngineeringInternal Medicine Residency Program

College of MedicineUniversity of Illinois at Urbana-Champaign

Röntgen In a dark room Röntgen passed

an electrostatic charge through a cathode tube generating a faint shimmering in a nearby barium platinocyanide screen.

An invisible rayAn x-ray

had passed from the tube to the screen.

Father of Diagnostic Radiology

Attenuation

Intensity, I, decreases exponentially with thickness, x.

The attenuation coefficient, μ, increases with increasing density, ρ, and vice versa

I x⎛⎝⎜⎜

⎞

⎠⎟⎟=I0e

−μx

Radiological DensitiesBiological

CompositionChemical

CompositionDensity, ρ

(kg/L)Air N2, O2, CO2 1.2

FatCH3(CH2)m(CH=CHCH2)n(

CH2)pCOO- 900

Water(Soft Tissue)

H2O 1000

MetalBone Ca10(PO4)6(OH)2

(hydroxyapatite)3160

Blood Minute Fe 7000

Attenuation Comparison

Thickness

Intensity

AirFatWaterBone

Density Gedanken Experiment

Attenuation Comparison

Negative Exposure Trickery

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Projection

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Projection

The point-of-view dependent, two-dimensional representation of a three-dimensional object

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Projection Gedanken Experiment

What’s this?

Focus

Focus Gedanken Experiment

PA and AP views

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Lateral View Localizes

STENTOR Teaching File

High IQ ABC’s Identification Quality Airway, aorta, and adenopathy Bones and breast shadow Cardiac silhouette Diaphragm Everything else Fields, fluid, and foreign objects Gastric air bubble History

Projected Anatomy

Where’s the mass?

MiddleMediastinum

Where’s the mass?

Posterior Mediastinum

Where’s the mass?

Where’s the mass?

61-year-old woman with dyspnea The inferior margin of the

opacity in the right upper thorax is due to the

A. major fissure in RUL collapse without a hilar mass.

B. minor fissure in RUL collapse with a hilar mass.

C. minor fissure in RUL collapse without a hilar mass.

D. major fissure in RUL collapse with a hilar mass.

61-year-old woman with dyspnea The inferior margin of the

opacity in the right upper thorax is due to the

A. major fissure in RUL collapse without a hilar mass.

B. minor fissure in RUL collapse with a hilar mass.

C. minor fissure in RUL collapse without a hilar mass.

D. major fissure in RUL collapse with a hilar mass.

61-year-old woman with dyspnea The inferior margin of the

opacity in the right upper thorax is due to the

A. major fissure in RUL collapse without a hilar mass.

B. minor fissure in RUL collapse with a hilar mass.

C. minor fissure in RUL collapse without a hilar mass.

D. major fissure in RUL collapse with a hilar mass.

45-year-old woman with chronic cough

All of the following are true with regard to right middle lobe collapse except

A. a triangular opacity is superimposed on the heart on the lateral radiograph.

B. the right heart border is obscured.

C. the minor fissure is inferiorly displaced.

D. the right heart border is shifted to the left.

45-year-old woman with chronic cough

All of the following are true with regard to right middle lobe collapse except

A. a triangular opacity is superimposed on the heart on the lateral radiograph.

B. the right heart border is obscured.

C. the minor fissure is inferiorly displaced.

D. the right heart border is shifted to the left.

45-year-old woman with chronic cough

All of the following are true with regard to right middle lobe collapse except

A. a triangular opacity is superimposed on the heart on the lateral radiograph.

B. the right heart border is obscured.

C. the minor fissure is inferiorly displaced.

D. the right heart border is shifted to the left.

62-year-old man with a cough productive of blood-tinged sputum

Signs of left lower lobe collapse include all of the following except

A. obscuration of the lateral wall of the descending thoracic aorta.

B. inferior displacement of the left hilum.

C. obliteration of the posterior aspect of the left hemidiaphragm on the lateral view.

D. triangular opacity in the left retrocardiac area on the frontal view.

E. shift of the major fissure toward the anterior chest wall on the lateral view.

62-year-old man with a cough productive of blood-tinged sputum

Signs of left lower lobe collapse include all of the following except

A. obscuration of the lateral wall of the descending thoracic aorta.

B. inferior displacement of the left hilum.

C. obliteration of the posterior aspect of the left hemidiaphragm on the lateral view.

D. triangular opacity in the left retrocardiac area on the frontal view.

E. shift of the major fissure toward the anterior chest wall on the lateral view.

62-year-old man with a cough productive of blood-tinged sputum

Signs of left lower lobe collapse include all of the following except

A. obscuration of the lateral wall of the descending thoracic aorta.

B. inferior displacement of the left hilum.

C. obliteration of the posterior aspect of the left hemidiaphragm on the lateral view.

D. triangular opacity in the left retrocardiac area on the frontal view.

E. shift of the major fissure toward the anterior chest wall on the lateral view.

49-year-old woman with cough Signs of left upper lobe collapse

include all of the following exceptA. crescent of air around the transverse

section of the aortic arch resulting from hyperexpansion of the superior segment of the left lower lobe.

B. anterior displacement of the left major fissure on the lateral view.

C. obscuration of the left heart border.D. tracheal deviation to the left.E. inferior displacement of the left

hilum.

49-year-old woman with cough Signs of left upper lobe collapse

include all of the following exceptA. crescent of air around the transverse

section of the aortic arch resulting from hyperexpansion of the superior segment of the left lower lobe.

B. anterior displacement of the left major fissure on the lateral view.

C. obscuration of the left heart border.D. tracheal deviation to the left.E. inferior displacement of the left

hilum.

49-year-old woman with cough Signs of left upper lobe collapse

include all of the following exceptA. crescent of air around the transverse

section of the aortic arch resulting from hyperexpansion of the superior segment of the left lower lobe.

B. anterior displacement of the left major fissure on the lateral view.

C. obscuration of the left heart border.D. tracheal deviation to the left.E. inferior displacement of the left

hilum.

Airror

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sprojects.mmi.mcgill.ca

40-year-old man with fever and dyspnea

The most likely diagnosis is

A. massive left pleural effusion.

B. total atelectasis of the left lung.

C. right pneumothorax.D. aplasia of the left lung.E. mediastinal hematoma.

40-year-old man with fever and dyspnea

The most likely diagnosis is

A. massive left pleural effusion.

B. total atelectasis of the left lung.

C. right pneumothorax.D. aplasia of the left lung.E. mediastinal hematoma.

Tall, 21-year-old man who noted the sudden onset of dyspnea, and right-sided pleuritic chest pain

The most likely diagnosis isA. pulmonary embolism.B. overinflation associated with

asthma.C. pneumothorax.D. normal chest, with a skin fold

projected over the right hemithorax.E. left lower lobe atelectasis.

Tall, 21-year-old man who noted the sudden onset of dyspnea, and right-sided pleuritic chest pain

The most likely diagnosis isA. pulmonary embolism.B. overinflation associated with

asthma.C. pneumothorax.D. normal chest, with a skin fold

projected over the right hemithorax.E. left lower lobe atelectasis.

62-year-old man with dyspnea that increased over 2 days

The most likely diagnosis is

A. left pleural effusion.B. collapse of the left lung.C. right pneumothorax.D. collapse of the right lung.E. mediastinal hematoma.

62-year-old man with dyspnea that increased over 2 days

The most likely diagnosis is

A. left pleural effusion.B. collapse of the left lung.C. right pneumothorax.D. collapse of the right lung.E. mediastinal hematoma.

COPD

STENTOR Teaching File

Silicosis

STENTOR Teaching File

Cystic Fibrosis

64-year-old man, Navy veteran, with a cough productive of blood-tinged sputum

The most likely diagnosis isA. progressive massive fibrosis,

due to silicosis.B. pneumonia in a patient with

chronic interstitial lung disease.

C. lung cancer in a patient with asbestosis.

D. rounded atelectasis in a patient with asbestosis.

E. berylliosis.

64-year-old man, Navy veteran, with a cough productive of blood-tinged sputum

The most likely diagnosis isA. progressive massive fibrosis,

due to silicosis.B. pneumonia in a patient with

chronic interstitial lung disease.

C. lung cancer in a patient with asbestosis.

D. rounded atelectasis in a patient with asbestosis.

E. berylliosis.

55-year-old man who worked as a coal miner for 30 years

The most likely diagnosis isA. progressive massive fibrosis,

due to silicosis.B. pneumonia in a patient with

chronic interstitial lung disease.

C. lung cancer in a patient with asbestosis.

D. rounded atelectasis in a patient with asbestosis.

E. berylliosis.

55-year-old man who worked as a coal miner for 30 years

The most likely diagnosis isA. progressive massive fibrosis,

due to silicosis.B. pneumonia in a patient with

chronic interstitial lung disease.

C. lung cancer in a patient with asbestosis.

D. rounded atelectasis in a patient with asbestosis.

E. berylliosis.

Pulmonary malignanciesBronchoalveolar

Carcinoma

1° SCCMetastasized Esophageal SCC

Chronic HistoplasmosisGranulomas

53-year-old man scheduled for coronary artery bypass grafting

Characteristics suggesting that a nodule is benign are

A. size of the nodule does not change over 2 years.

B. it contains central calcification.

C. CT attenuation values within the nodule are greater than 200 Hounsfield units (Hu).

D. all of the above.

53-year-old man scheduled for coronary artery bypass grafting

Characteristics suggesting that a nodule is benign are

A. size of the nodule does not change over 2 years.

B. it contains central calcification.

C. CT attenuation values within the nodule are greater than 200 Hounsfield units (Hu).

D. all of the above.

64-year-old man with cough and weight loss and a 50-pack-per-year history of tobacco use

The best description of the chest radiograph is

A. mass in the left upper lobe.B. left upper lobe collapse.C. mediastinal mass.D. consolidation of the left

upper lobe.E. enlargement of the left

pulmonary artery.

64-year-old man with cough and weight loss and a 50-pack-per-year history of tobacco use

The best description of the chest radiograph is

A. mass in the left upper lobe.B. left upper lobe collapse.C. mediastinal mass.D. consolidation of the left

upper lobe.E. enlargement of the left

pulmonary artery.

64-year-old man with cough and weight loss and a 50-pack-per-year history of tobacco use

The best description of the chest radiograph is

A. mass in the left upper lobe.B. left upper lobe collapse.C. mediastinal mass.D. consolidation of the left

upper lobe.E. enlargement of the left

pulmonary artery.

70-year-old woman with uterine carcinoma treated with surgical resection 3 years ago

The most likely cause of the multiple pulmonary nodules is

A. metastasis.B. herpes simplex pneumonia.C. histoplasmosis.D. Wegener's granulomatosis.E. arteriovenous malformations

70-year-old woman with uterine carcinoma treated with surgical resection 3 years ago

The most likely cause of the multiple pulmonary nodules is

A. metastasis.B. herpes simplex pneumonia.C. histoplasmosis.D. Wegener's granulomatosis.E. arteriovenous malformations

Airways

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Pneumonia

STENTOR Teaching File

Pneumonia

STENTOR Teaching File

32-year-old man with fever, cough, and hemoptysis

Which of the following is not an accurate descriptor of the opacity in the left upper lobe

A. Lobar distributionB. Ill-defined marginsC. Reticular patternD. Air bronchogramsE. Airspace disease

32-year-old man with fever, cough, and hemoptysis

Which of the following is not an accurate descriptor of the opacity in the left upper lobe

A. Lobar distributionB. Ill-defined marginsC. Reticular patternD. Air bronchogramsE. Airspace disease

57-year-old man with fever and a cough productive of purulent sputum

Which one of the following best explains the opacity in the left hemithorax?

A. Collapse of the left upper lobe due to bronchial obstruction

B. Airspace consolidation of the lingula

C. Empyema loculated within the left major fissure

D. Carcinoma in the left upper lobe

57-year-old man with fever and a cough productive of purulent sputum

Which one of the following best explains the opacity in the left hemithorax?

A. Collapse of the left upper lobe due to bronchial obstruction

B. Airspace consolidation of the lingula

C. Empyema loculated within the left major fissure

D. Carcinoma in the left upper lobe

69-year-old man with progressive dyspnea, orthopnea, and pedal edema and a history of

hypertension Which of the following best

describes the chest radiograph?

A. Normal heart size, alveolar pulmonary edema

B. Cardiomegaly, interstitial pulmonary edema, and small bilateral pleural effusions

C. Unilateral interstitial diseaseD. Cardiomegaly, oligemia in the

right lung

69-year-old man with progressive dyspnea, orthopnea, and pedal edema and a history of

hypertension Which of the following best

describes the chest radiograph?

A. Normal heart size, alveolar pulmonary edema

B. Cardiomegaly, interstitial pulmonary edema, and small bilateral pleural effusions

C. Unilateral interstitial diseaseD. Cardiomegaly, oligemia in the

right lung

Fluids and Gravity

Pleural Effusion

My First Thoracentesis

45-year-old man with increasing dyspnea and abdominal swelling of 1-week duration

Which of the following radiographic signs suggest the presence of pleural effusion?

A. Meniscus-shaped opacity in a posterior costophrenic angle on the lateral projection

B. Biconvex lens-shaped opacity projecting in the midthorax on the lateral projection

C. Fluid levels that have different lengths on the PA and lateral views in a hemithorax

D. Homogeneous increased density in a hemithorax with preservation of the vascular shadows in the lungs

E. Separation of the gastric air bubble from the inferior lung margin by more than 2 cm

45-year-old man with increasing dyspnea and abdominal swelling of 1-week duration

Which of the following radiographic signs suggest the presence of pleural effusion?

A. Meniscus-shaped opacity in a posterior costophrenic angle on the lateral projection

B. Biconvex lens-shaped opacity projecting in the midthorax on the lateral projection

C. Fluid levels that have different lengths on the PA and lateral views in a hemithorax

D. Homogeneous increased density in a hemithorax with preservation of the vascular shadows in the lungs

E. Separation of the gastric air bubble from the inferior lung margin by more than 2 cm

62-year-old woman with worsening shortness of breath and mild hemoptysis 1 day after receiving IV chemotherapy

The most likely cause for her dyspnea and hemoptysis is

A. pulmonary metastases.B. malignant pleural effusion.C. pulmonary embolism.D. septic emboli.E. drug-related pneumonitis.

62-year-old woman with worsening shortness of breath and mild hemoptysis 1 day after receiving IV chemotherapy

The most likely cause for her dyspnea and hemoptysis is

A. pulmonary metastases.B. malignant pleural effusion.C. pulmonary embolism.D. septic emboli.E. drug-related pneumonitis.

62-year-old woman with worsening shortness of breath and mild hemoptysis 1 day after receiving IV chemotherapy

The most likely cause for her dyspnea and hemoptysis is

A. pulmonary metastases.B. malignant pleural effusion.C. pulmonary embolism.D. septic emboli.E. drug-related pneumonitis.

The FinalCan you spot the pathology?

References Paul and Juhl’s Essentials of Radiologic Imaging,

11th edition Felson’s Principles of Chest Roentgenology, 2nd

edition Chen MYM, Pope TL, and Ott DJ, Basic

Radiology, The McGraw-Hill Companies, 2008