A chest radiograph, called a chest X-ray (CXR), or chest film, is a projection radiograph of the chest 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 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 radiography ("diagnostic" and "therapeu ...

, chest radiography employs

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

in the form of

X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

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 through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

dose to an adult from a chest radiograph is around 0.02

mSv mSv or MSV may refer to: * Maize streak virus, a plant disease * Medium-speed vehicle, US category * Medium Systems Vehicle, a class of fictional artificially intelligent starship in The Culture universe of late Scottish author Iain Banks * Millis ...

mrem The roentgen equivalent man (rem) is a CGS unit of equivalent dose, effective dose, and committed dose, which are dose measures used to estimate potential health effects of low levels of ionizing radiation on the human body. Quantities measu ...

) 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 inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severit ...

* Pneumothorax * Interstitial lung disease *

Heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

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 '' ...

* Hiatal hernia 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 organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

heart The heart is a muscular Organ (biology), organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as ca ...

, and great vessels.

and

congestive heart failure Heart failure (HF), also known as congestive heart failure (CHF), is a syndrome, a group of signs and symptoms caused by an impairment of the heart's blood pumping function. Symptoms typically include shortness of breath, excessive fatigue, ...

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), 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 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) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, ...

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 angle The costodiaphragmatic recess, also called the costophrenic recess or phrenicocostal sinus, costodiaphragmatic-recess Retrieved May 2011 Imaging In anatomy, the costophrenic angles are the places where the diaphragm (''-phrenic'') meets the ribs ...

s). * Lordotic view – used to visualize the

apex of the lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...

, to pick up abnormalities such as a Pancoast tumour. *

Expiratory Exhalation (or expiration) is the flow of the breath out of an organism. In animals, it is the movement of air from the lungs out of the airways, to the external environment during breathing. This happens due to elastic properties of the lungs, ...

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

Landmarks

Mediastinal structures on chest X-ray, annotated

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 Restrictive lung diseases are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygena ...

, pleural effusions or

atelectasis Atelectasis is the collapse or closure of a lung resulting in reduced or absent gas exchange. It is usually unilateral, affecting part or all of one lung. It is a condition where the alveoli are deflated down to little or no volume, as distinct ...

. 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, 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 ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esopha ...

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 inferenced by silhouetting and the

hilum overlay sign The hilum overlay sign is an imaging appearance on chest radiographs in which the outline of the hilum can be seen at the level of a mass or collection in the mid chest. It implies that the mass is not in the middle mediastinum, and is either fro ...

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

lung nodule A lung nodule or pulmonary nodule is a relatively small focal density in the lung. A solitary pulmonary nodule (SPN) or coin lesion, is a mass in the lung smaller than three centimeters in diameter. A pulmonary micronodule has a diameter of less ...

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), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...

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

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 tumour/malignant granuloma ** Doubling time of more than 24 months: benign nodule neoplasm *

calcification Calcification is the accumulation of calcium salts in a body tissue. It normally occurs in the formation of bone, but calcium can be deposited abnormally in soft tissue,Miller, J. D. Cardiovascular calcification: Orbicular origins. ''Nature M ...

* 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 spread 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, the ...

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include en ...

hamartoma A hamartoma is a mostly benign, local malformation of cells that resembles a neoplasm of local tissue but is usually due to an overgrowth of multiple aberrant cells, with a basis in a systemic genetic condition, rather than a growth descended f ...

sarcoidosis Sarcoidosis (also known as ''Besnier-Boeck-Schaumann disease'') is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomata. The disease usually begins in the lungs, skin, or lymph nodes. Less commonly af ...

* alveolitis *auto-immune disease: e.g.,

*inhalation (e.g.,

pneumoconiosis Pneumoconiosis is the general term for a class of interstitial lung disease where inhalation of dust ( for example, ash dust, lead particles, pollen grains etc) has caused interstitial fibrosis. The three most common types are asbestosis, silico ...

)

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 abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

* 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 posit ...

'',

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

Granulomatosis with polyangiitis Granulomatosis with polyangiitis (GPA), previously known as Wegener's granulomatosis (WG), is a rare long-term systemic disorder that involves the formation of granulomas and inflammation of blood vessels (vasculitis). It is a form of vasculitis ...

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

on the lateral chest radiograph and 200 mL of pleural fluid in order to blunt the

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 Lenticular is an adjective often relating to lenses. It may refer to: * A term used with two meanings in botany: see * Lenticular cloud, a lens-shaped cloud * Lenticular galaxy, a lens-shaped galaxy * Lenticular (geology), adjective describing a ...

shape (the fluid making an

obtuse angle In Euclidean geometry, an angle is the figure formed by two rays, called the '' sides'' of the angle, sharing a common endpoint, called the ''vertex'' of the angle. Angles formed by two rays lie in the plane that contains the rays. Angles ...

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, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dise ...

. 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 Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silic ...

ankylosing spondylitis Ankylosing spondylitis (AS) is a type of arthritis characterized by long-term inflammation of the joints of the spine typically where the spine joins the pelvis. Occasionally areas affected may include other joints such as the shoulders or hi ...

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

pulmonary edema Pulmonary edema, also known as pulmonary congestion, is excessive liquid accumulation in the tissue and air spaces (usually alveoli) of the lungs. It leads to impaired gas exchange and may cause hypoxemia and respiratory failure. It is due ...

, alveolar proteinosis,

, Kaposi's sarcoma, 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, 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 :*

:*radiation fibrosis :*

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

:* lymphangitis carcinomatosa :* PCP ;Nodular pattern :*

/pneumoconiosis :*

extrinsic allergic alveolitis Hypersensitivity pneumonitis (HP) or extrinsic allergic alveolitis (EAA) is a syndrome caused by the repetitive inhalation of antigens from the environment in susceptible or sensitized people. Common antigens include molds, bacteria, bird dropping ...

;* Langerhans cell histiocytosis ;* lymphangitis carcinomatosa ;*

miliary tuberculosis To disseminate (from lat. ''disseminare'' "scattering seeds"), in the field of communication, is to broadcast a message to the public without direct feedback from the audience. Meaning Dissemination takes on the theory of the traditional view ...

;Cystic :* cryptogenic fibrosing alveolitis (late stage "honeycomb lung") :*cystic

bronchiectasis Bronchiectasis is a disease in which there is permanent enlargement of parts of the airways of the lung. Symptoms typically include a chronic cough with mucus production. Other symptoms include shortness of breath, coughing up blood, and chest ...

:* Langerhans cell histiocytosis :* lymphangioleiomyomatosis PneumonisWedge09

;Ground glass :*

:* desquamative interstitial pneumonia :* alveolar proteinosis :*

infant respiratory distress syndrome Infantile respiratory distress syndrome (IRDS), also called respiratory distress syndrome of newborn, or increasingly surfactant deficiency disorder (SDD), and previously called hyaline membrane disease (HMD), is a syndrome in premature infants ...

(RDS) ;Consolidation :*

pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severit ...

:*alveolar haemorrhage :*

alveolar cell carcinoma Adenocarcinoma in situ (AIS) of the lung —previously included in the category of "bronchioloalveolar carcinoma" (BAC)—is a subtype of lung adenocarcinoma. It tends to arise in the distal bronchioles or alveoli and is defined by a non-invasive ...

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

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 is a specialized primary lymphoid organ of the immune system. Within the thymus, thymus cell lymphocytes or '' T cells'' mature. T cells are critical to the adaptive immune system, where the body adapts to specific foreign invaders ...

, which can give the impression of a

widened mediastinum The mediastinum (from ) is the central compartment of the thoracic cavity. Surrounded by loose connective tissue, it is an undelineated region that contains a group of structures within the thorax, namely the heart and its vessels, the esophagu ...

.(CC BY 4.0)
/ref> File:Supraclavicular fossa on chest X-ray.jpg, The inferior skin folds of the

supraclavicular fossa The Supraclavicular fossa is an indentation (fossa) immediately above the clavicle. In terminologia anatomica, it is divided into ''fossa supraclavicularis major'' and ''fossa supraclavicularis minor'' Fullness in the supraclavicular fossa can be ...

may give the impression of a periosteal reaction of the

clavicle The clavicle, or collarbone, is a slender, S-shaped long bone approximately 6 inches (15 cm) long that serves as a strut between the shoulder blade and the sternum (breastbone). There are two clavicles, one on the left and one on the r ...

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, 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 Bronchopulmonary dysplasia (BPD; part of the spectrum of chronic lung disease of infancy) is a chronic lung disease in which premature infants, usually those who were treated with supplemental oxygen, require long-term oxygen. The alveoli that are ...

. File:Implantable cardioverter defibrillator chest X-ray.jpg, A chest film after insertion of an implantable cardioverter-defibrillator, showing the

shock Shock may refer to: Common uses Collective noun *Shock, a historic commercial term for a group of 60, see English numerals#Special names * Stook, or shock of grain, stacked sheaves Healthcare * Shock (circulatory), circulatory medical emerge ...

generator in the upper left chest and the electrical lead inside the right heart. Note both radio-opaque coils along the device lead.

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)