A chest radiograph, chest X-ray (CXR), or chest film is a projection radiograph of the

chest The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

used to diagnose conditions affecting the chest, its contents, and nearby structures. Chest radiographs are the most common film taken in medicine. Like all methods of

radiography Radiography is an imaging technology, imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical ("diagnostic" radiog ...

, chest radiography employs

ionizing radiation Ionizing (ionising) radiation, including Radioactive decay, nuclear radiation, consists of subatomic particles or electromagnetic waves that have enough energy per individual photon or particle to ionization, ionize atoms or molecules by detaching ...

in the form of

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

s to generate images of the chest. The mean

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: * ''electromagnetic radiation'' consisting of photons, such as radio waves, microwaves, infr ...

dose to an adult from a chest radiograph is around 0.02 mSv (2 mrem) for a front view (PA, or posteroanterior) and 0.08 mSv (8 mrem) for a side view (LL, or latero-lateral). Together, this corresponds to a background radiation equivalent time of about 10 days.

Medical uses

Conditions commonly identified by chest radiography *

Pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

Pneumothorax A pneumothorax is collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way valve is ...

* Interstitial lung disease *

Heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to Cardiac cycle, fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF ...

Bone fracture A bone fracture (abbreviated FRX or Fx, Fx, or #) is a medical condition in which there is a partial or complete break in the continuity of any bone in the body. In more severe cases, the bone may be broken into several fragments, known as a ''c ...

* Hiatal hernia * Pulmonary tuberculosis Chest radiographs are used to diagnose many conditions involving the chest wall, including its bones, and also structures contained within the thoracic cavity including the

lung The lungs are the primary Organ (biology), organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods, two lungs are located near the Vertebral column, backbone on either side of the heart. Their ...

heart The heart is a muscular Organ (biology), organ found in humans and other animals. This organ pumps blood through the blood vessels. The heart and blood vessels together make the circulatory system. The pumped blood carries oxygen and nutrie ...

, and great vessels.

and

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome caused by an impairment in the heart's ability to fill with and pump blood. Although symptoms vary based on which side of the heart is affected, HF typically pr ...

are very commonly diagnosed by chest radiograph. Chest radiographs are also used to screen for job-related lung disease in industries such as mining where workers are exposed to dust. For some conditions of the chest, radiography is good for screening but poor for diagnosis. When a condition is suspected based on chest radiography, additional imaging of the chest can be obtained to definitively diagnose the condition or to provide evidence in favor of the diagnosis suggested by initial chest radiography. Unless a fractured rib is suspected of being displaced, and therefore likely to cause damage to the lungs and other tissue structures, x-ray of the chest is not necessary as it will not alter patient management. The main regions where a chest X-ray may identify problems may be summarized as ''ABCDEF'' by their first letters: *Airways, including hilar adenopathy or enlargement *Breast shadows *Bones, e.g. rib fractures and lytic bone lesions *Cardiac silhouette, detecting cardiac enlargement *Costophrenic angles, including pleural effusions *Diaphragm, e.g. evidence of free air, indicative of perforation of an abdominal viscus *Edges, e.g. apices for fibrosis, pneumothorax, pleural thickening or plaques *Extrathoracic tissues *Fields (

lung parenchyma file:emphysema, bullous, subpleural and honeycomb fibrosis (4563270966).jpg, upright=1.6, Lung parenchyma showing damage due to large subpleural Focal lung pneumatosis, bullae. Parenchyma () is the bulk of functional substance in an animal org ...

), being evidence of alveolar flooding *Failure, e.g. alveolar air space disease with prominent vascularity with or without pleural effusions

Views

Different ''views'' (also known as ''projections'') of the chest can be obtained by changing the relative orientation of the body and the direction of the x-ray beam. The most common views are ''posteroanterior'', ''anteroposterior'', and ''lateral''. In a posteroanterior (PA) view, the x-ray source is positioned so that the x-ray beam enters through the posterior (back) aspect of the chest and exits out of the anterior (front) aspect, where the beam is detected. To obtain this view, the patient stands facing a flat surface behind which is an x-ray detector. A radiation source is positioned behind the patient at a standard distance (most often 6 feet, 1,8m), and the x-ray beam is fired toward the patient. In anteroposterior (AP) views, the positions of the x-ray source and detector are reversed: the x-ray beam enters through the anterior aspect and exits through the posterior aspect of the chest. AP chest x-rays are harder to read than PA x-rays and are therefore generally reserved for situations where it is difficult for the patient to get an ordinary chest x-ray, such as when the patient is bedridden. In this situation, mobile X-ray equipment is used to obtain a lying down chest x-ray (known as a "supine film"). As a result, most supine films are also AP. Lateral views of the chest are obtained in a similar fashion as the posteroanterior views, except in the lateral view, the patient stands with both arms raised and the left side of the chest pressed against a flat surface.

Typical views

Required projections can vary by country and hospital, although an erect posteroanterior (PA) projection is typically the first preference. If this is not possible, then an anteroposterior view will be taken. Further imaging depends on local protocols which is dependent on the hospital protocols, the availability of other imaging modalities and the preference of the image interpreter. In the UK, the standard chest radiography protocol is to take an erect posteroanterior view only and a lateral one only on request by a radiologist. In the US, chest radiography includes a PA and Lateral with the patient standing or sitting up. Special projections include an AP in cases where the image needs to be obtained stat (immediately) and with a portable device, particularly when a patient cannot be safely positioned upright. Lateral decubitus may be used for visualization of air-fluid levels if an upright image cannot be obtained. Anteroposterior (AP) Axial Lordotic projects the clavicles above the lung fields, allowing better visualization of the apices (which is extremely useful when looking for evidence of primary

tuberculosis Tuberculosis (TB), also known colloquially as the "white death", or historically as consumption, is a contagious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can al ...

Additional views

* Decubitus – taken while the patient is lying down, typically on their side. Useful for differentiating pleural effusions from consolidation (e.g. pneumonia) and loculated effusions from free fluid in the pleural space. In effusions, the fluid ''layers out'' (by comparison to an up-right view, when it often accumulates in the costophrenic angles). * Lordotic view – used to visualize the apex of the lung, to pick up abnormalities such as a Pancoast tumor. * Expiratory view – helpful for the diagnosis of

pneumothorax A pneumothorax is collection of air in the pleural space between the lung and the chest wall. Symptoms typically include sudden onset of sharp, one-sided chest pain and dyspnea, shortness of breath. In a minority of cases, a one-way valve is ...

. * Oblique view – useful for the visualization of the ribs and sternum. Although it is necessary to do the appropriate adaptations to the x-ray dosage to be used.

Landmarks

In the average person, the diaphragm should be intersected by the 5th to 7th anterior ribs at the mid-clavicular line, and 9 to 10 posterior ribs should be viewable on a normal PA inspiratory film. An increase in the number of viewable ribs implies hyperinflation, as can occur, for example, with obstructive lung disease or foreign body aspiration. A decrease implies hypoventilation, as can occur with restrictive lung disease, pleural effusions or atelectasis. Underexpansion can also cause interstitial markings due to parenchymal crowding, which can mimic the appearance of interstitial lung disease. Enlargement of the right descending pulmonary artery can indirectly reflect changes of

pulmonary hypertension Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the pulmonary artery, arteries of the lungs. Symptoms include dypsnea, shortness of breath, Syncope (medicine), fainting, tiredness, chest pain, pedal edema, swell ...

, with a size greater than 16 mm abnormal in men and 15 mm in women. Appropriate penetration of the film can be assessed by faint visualization of the thoracic spines and lung markings behind the heart. The right diaphragm is usually higher than the left, with the liver being situated beneath it in the abdomen. The minor fissure can sometimes be seen on the right as a thin horizontal line at the level of the fifth or sixth rib. Splaying of the carina can also suggest a tumor or process in the middle

mediastinum The mediastinum (from ;: mediastina) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is a region that contains vital organs and structures within the thorax, mainly the heart and its vessels, the eso ...

or enlargement of the left atrium, with a normal angle of approximately 60 degrees. The right paratracheal stripe is also important to assess, as it can reflect a process in the posterior mediastinum, in particular the spine or paraspinal soft tissues; normally it should measure 3 mm or less. The left paratracheal stripe is more variable and only seen in 25% of normal patients on posteroanterior views. Localization of lesions or inflammatory and infectious processes can be difficult to discern on chest radiograph, but can be inferred by silhouetting and the hilum overlay sign with adjacent structures. If either hemidiaphragm is blurred, for example, this suggests the lesion to be from the corresponding lower lobe. If the right heart border is blurred, than the pathology is likely in the right middle lobe, though a cavum deformity can also blur the right heard border due to indentation of the adjacent sternum. If the left heart border is blurred, this implies a process at the lingula.

Abnormalities

Nodule

A lung nodule is a discrete opacity in the lung which may be caused by: *

Neoplasm A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

: benign or malignant * Granuloma:

* Infection: round pneumonia * Vascular: infarct, varix,

granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis (WG), after Nazi German physician Friedrich Wegener, is a rare, long-term, systemic disorder that involves the formation of granulomas and vasculitis, inflammatio ...

rheumatoid arthritis Rheumatoid arthritis (RA) is a long-term autoimmune disorder that primarily affects synovial joint, joints. It typically results in warm, swollen, and painful joints. Pain and stiffness often worsen following rest. Most commonly, the wrist and h ...

There are a number of features that are helpful in suggesting the diagnosis: * rate of growth ** Doubling time of less than one month: sarcoma/infection/infarction/vascular ** Doubling time of six to 18 months: benign tumor/malignant granuloma ** Doubling time of more than 24 months: benign nodule neoplasm * calcification * margin ** smooth ** lobulated ** presence of a corona radiata * shape * site If the nodules are multiple, the differential is then smaller: *infection:

, fungal infection, septic emboli *neoplasm: e.g.,

metastases Metastasis is a pathogenic agent's spreading from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, ...

, lymphoma, hamartoma * sarcoidosis * alveolitis *auto-immune disease: e.g.,

*inhalation (e.g., pneumoconiosis)

Cavities

A cavity is a walled hollow structure within the lungs. Diagnosis is aided by noting: *wall thickness *wall outline *changes in the surrounding lung The causes include: *

cancer Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Po ...

* infarct (usually from a pulmonary embolus) *infection: e.g., ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often posi ...

'',

, Gram negative bacteria (especially '' Klebsiella pneumoniae''), anaerobic bacteria, and fungus *

Granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), formerly known as Wegener's granulomatosis (WG), after Nazi German physician Friedrich Wegener, is a rare, long-term, systemic disorder that involves the formation of granulomas and vasculitis, inflammatio ...

Pleural abnormalities

Fluid in space between the lung and the chest wall is termed a pleural effusion. There needs to be at least 75 mL of pleural fluid in order to blunt the costophrenic angle on the lateral chest radiograph and 200 mL of pleural fluid in order to blunt the costophrenic angle on the posteroanterior chest radiograph. On a lateral decubitus, amounts as small as 50ml of fluid are possible. Pleural effusions typically have a meniscus visible on an erect chest radiograph, but loculated effusions (as occur with an empyema) may have a lenticular shape (the fluid making an obtuse angle with the chest wall). Pleural thickening may cause blunting of the costophrenic angle, but is distinguished from pleural fluid by the fact that it occurs as a linear shadow ascending vertically and clinging to the ribs.

Diffuse shadowing

The differential for diffuse shadowing is very broad and can defeat even the most experienced radiologist. It is seldom possible to reach a diagnosis on the basis of the chest radiograph alone: high-resolution CT of the chest is usually required and sometimes a lung

biopsy A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, an interventional radiologist, or an interventional cardiology, interventional cardiologist. The process involves the extraction of sampling (medicine), sample ...

. The following features should be noted: *type of shadowing (lines, dots or rings) **reticular (crisscrossing lines) ** companion shadow (lines paralleling bony landmarks) **nodular (many small dots) **rings or cysts **ground glass **consolidation (diffuse opacity with air bronchograms) *location (where is the lesion worst?) **upper (e.g., sarcoid,

, silicosis/ pneumoconiosis, ankylosing spondylitis, Langerhans cell histiocytosis) **lower (e.g., cryptogenic fibrosing alveolitis, connective tissue disease, asbestosis, drug reactions) **central (e.g.,

pulmonary edema Pulmonary edema (British English: oedema), also known as pulmonary congestion, is excessive fluid accumulation in the tissue or air spaces (usually alveoli) of the lungs. This leads to impaired gas exchange, most often leading to shortness ...

, alveolar proteinosis, lymphoma,

Kaposi's sarcoma Kaposi's sarcoma (KS) is a type of cancer that can form masses on the skin, in lymph nodes, in the mouth, or in other organs. The skin lesions are usually painless, purple and may be flat or raised. Lesions can occur singly, multiply in a limite ...

, PCP) **peripheral (e.g., cryptogenic fibrosing alveolitis, connective tissue disease, chronic eosinophilic pneumonia, bronchiolitis obliterans organizing pneumonia) *lung volume **increased (e.g., Langerhans cell histiocytosis, lymphangioleiomyomatosis,

cystic fibrosis Cystic fibrosis (CF) is a genetic disorder inherited in an autosomal recessive manner that impairs the normal clearance of Sputum, mucus from the lungs, which facilitates the colonization and infection of the lungs by bacteria, notably ''Staphy ...

, allergic bronchopulmonary aspergillosis) **decreased (e.g., fibrotic lung disease, chronic sarcoidosis, chronic extrinsic allergic alveolitis) Pleural effusions may occur with cancer, sarcoid, connective tissue diseases and lymphangioleiomyomatosis. The presence of a pleural effusion argues against pneumocystis pneumonia. ;Reticular (linear) pattern :(sometimes called "reticulonodular" because of the appearance of nodules at the intersection of the lines, even though there are no true nodules present) :* idiopathic pulmonary fibrosis :* connective tissue disease :* sarcoidosis :*radiation fibrosis :*

asbestosis Asbestosis is long-term inflammation and pulmonary fibrosis, scarring of the human lung, lungs due to asbestos fibers. Symptoms may include shortness of breath, cough, wheezing, and chest pain, chest tightness. Complications may include lung canc ...

:* lymphangitis carcinomatosa :* PCP ;Nodular pattern :* sarcoidosis :* silicosis/pneumoconiosis :* extrinsic allergic alveolitis ;* Langerhans cell histiocytosis ;* lymphangitis carcinomatosa ;* miliary tuberculosis ;*

;Cystic :* cryptogenic fibrosing alveolitis (late stage "honeycomb lung") :*cystic bronchiectasis :* Langerhans cell histiocytosis :* lymphangioleiomyomatosis PneumonisWedge09

;Ground glass :* extrinsic allergic alveolitis :* desquamative interstitial pneumonia :* alveolar proteinosis :* infant respiratory distress syndrome (RDS) ;Consolidation :*

pneumonia Pneumonia is an Inflammation, inflammatory condition of the lung primarily affecting the small air sacs known as Pulmonary alveolus, alveoli. Symptoms typically include some combination of Cough#Classification, productive or dry cough, ches ...

:*alveolar haemorrhage :* alveolar cell carcinoma :*

vasculitis Vasculitis is a group of disorders that destroy blood vessels by inflammation. Both artery, arteries and veins are affected. Lymphangitis (inflammation of lymphatic vessels) is sometimes considered a type of vasculitis. Vasculitis is primarily c ...

Signs

:*The silhouette sign is especially helpful in localizing lung lesions. (e.g., loss of right heart border in right middle lobe pneumonia),Chest X-Ray
OB-GYN 101: Introductory Obstetrics & Gynecology. © 2003, 2004, 2005, 2008 Medical Education Division, Brookside Associates, Ltd. Retrieved 9 February 2010. :*The air bronchogram sign, where branching radiolucent columns of air corresponding to bronchi is seen, usually indicates air-space (alveolar) disease, as from blood, pus, mucus, cells, protein surrounding the air bronchograms. This is seen in Respiratory distress syndrome

Disease mimics

Disease mimics are visual artifacts, normal anatomic structures or harmless variants that may simulate diseases and abnormalities. File:X-ray of an infant with a prominent thymus.jpg, A prominent

thymus The thymus (: thymuses or thymi) is a specialized primary lymphoid organ of the immune system. Within the thymus, T cells mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders. The thymus ...

, which can give the impression of a widened mediastinum.(CC BY 4.0)
/ref> File:Supraclavicular fossa on chest X-ray.jpg, The inferior skin folds of the supraclavicular fossa may give the impression of a periosteal reaction of the

clavicle The clavicle, collarbone, or keybone is a slender, S-shaped long bone approximately long that serves as a strut between the scapula, shoulder blade and the sternum (breastbone). There are two clavicles, one on each side of the body. The clavic ...

Limitations

While chest radiographs are a relatively cheap and safe method of investigating diseases of the chest, there are a number of serious chest conditions that may be associated with a normal chest radiograph and other means of assessment may be necessary to make the diagnosis. For example, a patient with an acute myocardial infarction may have a completely normal chest radiograph.

Gallery

File:Chest Xray PA 3-8-2010 inverted.png, Chest X-ray PA inverted and enhanced. File:Projectional rendering of CT scan of thorax (thumbnail).gif, Projectionally rendered

CT scan A computed tomography scan (CT scan), formerly called computed axial tomography scan (CAT scan), is a medical imaging technique used to obtain detailed internal images of the body. The personnel that perform CT scans are called radiographers or ...

, showing the transition of thoracic structures between the anteroposterior and lateral view File:SARS xray.jpg, Chest film showing increased opacity in both lungs, indicative of pneumonia File:CXR - Bronchopulmonary dysplasia.jpg, A chest radiograph showing bronchopulmonary dysplasia. File:Implantable cardioverter defibrillator chest X-ray.jpg, A chest film after insertion of an implantable cardioverter-defibrillator, showing the shock generator in the upper left chest and the electrical lead inside the right heart. Note both radio-opaque coils along the device lead. File:ETTubeandNGtubeMarked.png, Portable chest (ie, antero-posterior view) showing endotracheal tube and Levin tube, both properly in place.

References

External links

Chest X-ray Atlas

USUHS: Basic Chest X-Ray Review

Database of chest radiology related to emergency medicine

* ttps://web.archive.org/web/20071217020540/http://www.chestradiology.net/ Chest Radiology TutorialsFree Web Tutorials for Chest Anatomy and Lung Malignancies in Radiology
Yale: Introduction to Cardiothoracic Imaging
{{DEFAULTSORT:Chest Radiograph Projectional radiography Thorax (human anatomy)