Hubbry Logo
Chest radiographChest radiographMain
Open search
Chest radiograph
Community hub
Chest radiograph
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Chest radiograph
Chest radiograph
Chest radiograph
View on Wikipedia
from Wikipedia
Chest radiograph
A normal posteroanterior (PA) chest radiograph of someone without any signs of injury. Dx and Sin stand for "right" and "left" respectively.
SpecialtyRadiology
ICD-9-CM87.3-87.4
MeSHD013902
MedlinePlus003804

A chest radiograph, 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, chest radiography employs ionizing radiation in the form of X-rays to generate images of the chest. The mean radiation 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).[1] Together, this corresponds to a background radiation equivalent time of about 10 days.[2]

Medical uses

[edit]
Dedicated chest radiography room

Conditions commonly identified by chest radiography

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 lungs, heart, and great vessels. Pneumonia and congestive heart failure 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.[3]

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:[4]

  • 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

[edit]
Positioning for a PA chest x-ray
Normal lateral chest radiograph.

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 [citation needed] 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

[edit]

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.[5] 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).

Additional views

[edit]
  • 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.
  • 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

[edit]
A chest radiograph with the angle parts of the ribs and some other landmarks labeled.
Mediastinal structures on a chest radiograph.

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, with a size greater than 16 mm abnormal in men and 15 mm in women.[6]

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 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.[7]

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.[8]

Abnormalities

[edit]

Nodule

[edit]

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

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:

Cavities

[edit]

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:

Pleural abnormalities

[edit]

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

[edit]

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. The following features should be noted:

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)
Nodular pattern
Cystic
A chest X-ray showing a very prominent wedge-shape area of airspace consolidation in the right lung characteristic of acute bacterial lobar pneumonia.
Ground glass
Consolidation

Signs

[edit]
  • The silhouette sign is especially helpful in localizing lung lesions. (e.g., loss of right heart border in right middle lobe pneumonia),[9]
  • 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[9]

Disease mimics

[edit]

Disease mimics are visual artifacts, normal anatomic structures or harmless variants that may simulate diseases and abnormalities.

Limitations

[edit]

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.

[edit]
  • Chest X-ray PA inverted and enhanced.
    Chest X-ray PA inverted and enhanced.
  • Projectionally rendered CT scan, showing the transition of thoracic structures between the anteroposterior and lateral view
    Projectionally rendered CT scan, showing the transition of thoracic structures between the anteroposterior and lateral view
  • Chest film showing increased opacity in both lungs, indicative of pneumonia
    Chest film showing increased opacity in both lungs, indicative of pneumonia
  • A chest radiograph showing bronchopulmonary dysplasia.
    A chest radiograph showing bronchopulmonary dysplasia.
  • 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.
    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.
  • Portable chest (ie, antero-posterior view) showing endotracheal tube and Levin tube, both properly in place.
    Portable chest (ie, antero-posterior view) showing endotracheal tube and Levin tube, both properly in place.

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Chest radiograph

View on Grokipedia
from Grokipedia
A chest radiograph, also known as a chest X-ray, is a noninvasive medical imaging procedure that employs low-dose ionizing radiation to generate two-dimensional projections of the thoracic cavity, visualizing key structures such as the lungs, heart, ribs, diaphragm, and mediastinum. This technique allows for the rapid assessment of pulmonary, cardiac, and skeletal abnormalities, making it one of the most frequently performed radiographic examinations worldwide. The development of chest radiography traces its origins to the discovery of X-rays by Wilhelm Röntgen in 1895, with the first clinical applications to chest imaging occurring as early as 1896, enabling the visualization of thoracic pathologies that were previously undetectable. Over the subsequent decades, advancements in radiographic technology, including the standardization of posterior-anterior (PA) and lateral views, have refined its diagnostic precision; the PA view, typically acquired at a 6-foot source-to-image distance, minimizes magnification of the heart and provides optimal lung field clarity, while the lateral view aids in depth localization of lesions. Performed in an upright position with the patient holding a deep breath to enhance lung expansion, the procedure exposes patients to a minimal effective radiation dose of approximately 0.01–0.02 mSv, comparable to a few days of natural background radiation, though precautions are advised for pregnant individuals due to fetal sensitivity. Chest radiographs serve as a in clinical practice for evaluating a broad spectrum of conditions, including respiratory infections like , obstructive diseases such as (COPD), cardiac issues like , and traumatic injuries involving the . They are particularly valuable in emergency settings for detecting life-threatening entities, such as or , and for monitoring chronic illnesses or device placements like endotracheal tubes, often guiding decisions on whether advanced imaging like computed tomography is warranted. Despite its accessibility and cost-effectiveness, the interpretation requires systematic evaluation of normal (e.g., clear lung fields, midline trachea, and cardiothoracic ratio under 50%) against deviations like opacities or shifts, with correlation to clinical history to optimize accuracy.

Overview

Definition and Purpose

A chest radiograph, commonly abbreviated as CXR, is a two-dimensional projection X-ray image of the chest that captures key structures including the lungs, heart, ribs, and diaphragm. This imaging modality serves as a foundational diagnostic tool in medical practice, providing a non-invasive means to visualize thoracic anatomy. The term "radiograph" derives from the Latin "radius" meaning ray and Greek "-graphy" meaning writing or recording, reflecting the process of capturing images through radiation. The procedure employs , typically X-rays, which pass through the body and are differentially absorbed by tissues based on their density and , resulting in images. In these images, low-density structures like air in the lungs appear black due to minimal , while high-density tissues such as appear white from greater absorption of the beam. This contrast enables differentiation of anatomical features and potential abnormalities. The primary purposes of a chest radiograph include the initial assessment of respiratory symptoms like or persistent , evaluation of cardiac conditions, detection of trauma-related injuries, and monitoring of chronic illnesses affecting the . It is often the first-line imaging study due to its accessibility, low cost, and ability to provide rapid diagnostic insights in both acute and routine clinical settings. Common abbreviations also encompass PA chest , referring to the standard posteroanterior projection.

Historical Development

The discovery of X-rays by Wilhelm Conrad Röntgen on November 8, 1895, marked the foundational event in the development of chest radiography, as he observed these rays penetrating materials to produce shadow images on fluorescent screens during experiments with cathode-ray tubes at the . Röntgen's subsequent publication in December 1895 detailed the properties of these "X-rays," leading to rapid medical adoption; the first radiographic image was of his wife's hand, revealing skeletal structures, and by 1896, X-rays were applied to visualize lung pathologies. In the early , chest radiography emerged as a critical tool for (TB) screening, a leading cause of death at the time, enabling non-invasive detection of pulmonary infiltrates and cavities in sanatoria and initiatives across and North America. During (1914–1918), the introduction of portable units revolutionized battlefield imaging, including chest examinations for TB and trauma-related lung injuries, with physicist developing over 20 mobile "Little Curies" vehicles equipped with generators and darkrooms to scan wounded soldiers near the front lines. These units facilitated rapid diagnosis amid resource constraints, saving countless lives by identifying conditions like and early TB reactivation in troops. In the , advancements in film-screen systems improved chest image quality and accessibility; Kodak's introduction of cellulose triacetate-based film replaced flammable nitrate bases, while latitude-type films were optimized for the wide density range in chest exams, from aerated lungs to dense , enabling mass screening programs. The 1930s saw standardization of chest X-ray protocols amid intensified TB campaigns, with mass miniature radiography (using photofluorography on small films) deployed in mobile units like buses to screen millions in industrialized nations, establishing systematic PA and lateral views for consistent interpretation. Radiologists such as those in the U.S. Public Health Service contributed to protocols emphasizing double-reading to reduce false positives, supporting global efforts that screened over 100 million individuals by the decade's end. The shift to digital radiography began with computed radiography (CR) in 1983, when Fuji introduced the first photostimulable phosphor system, allowing laser scanning of storage plates to produce digital images and eliminating wet chemical processing for faster chest workflows. Direct digital radiography (DR) emerged in the late 1990s and proliferated in the 2000s with flat-panel detectors, enabling real-time acquisition without intermediate plates; by the mid-2000s, amorphous and cesium iodide panels were standard for chest , reducing processing time from minutes to seconds and improving for better visualization of subtle abnormalities while lowering doses by up to 50% compared to film-screen systems. These innovations enhanced image quality, supported computer-aided detection, and facilitated telemedicine in TB-endemic regions.

Acquisition and Technique

Patient Preparation and Positioning

Patient preparation for a chest radiograph begins with informing the individual about the procedure to alleviate anxiety and ensure cooperation, as clear communication helps minimize movement artifacts during imaging. No or special dietary restrictions are required prior to the examination. Patients are instructed to remove jewelry, eyeglasses, dental appliances, and any metal objects or clothing that could create artifacts on the image, and they may be asked to wear a loose-fitting for the procedure. Women of childbearing age should inform the technologist if there is any possibility of to allow for appropriate precautions. Standard positioning for the posteroanterior (PA) view involves standing erect with their chest pressed firmly against the image receptor, chin slightly elevated to avoid overlap with the , and hands placed on the hips with palms outward and shoulders rolled forward to rotate the scapulae away from the fields. is instructed to take a deep breath and hold it at full inspiration to expand the fully, enabling visualization of approximately 5 to 7 anterior ribs above the diaphragm, which reduces vascular crowding and improves diagnostic quality. For the lateral view, stands with their left side against the receptor, arms raised and crossed above the head, again at full inspiration to optimize expansion. For patients unable to stand, such as those who are or in trauma settings, an anteroposterior (AP) supine projection is performed with the patient lying flat on their back, using a portable unit if necessary, though this may result in of the heart and . In lateral decubitus views, used to assess for free pleural fluid or air, the patient lies on their side for several minutes prior to imaging to allow redistribution, with expiration sometimes employed to enhance detection of small effusions by reducing volume. Special considerations apply to pediatric patients, where immobilization techniques such as or parental holding with lead apron protection may be used to prevent motion, and is rarely required for routine chest radiographs due to the brevity of the procedure. For pregnant patients, the examination is justified only if essential, with efforts to adhere to the ALARA (as low as reasonably achievable) principle for ; recent guidelines recommend against routine fetal shielding as it can obscure diagnostic areas without significant dose reduction benefit, and a single frontal view may suffice in some cases. Elderly or mobility-impaired individuals, including trauma cases, often require assistive devices or positioning to ensure safety and feasibility, with technologists providing support to maintain alignment.

Imaging Process and Radiation Exposure

The imaging process for a chest radiograph begins with an , consisting of a that emits and an that serves as the target for electron acceleration, generating X-rays through and characteristic . These X-rays are directed toward the patient, with collimation used to restrict the beam to the chest area (typically 35 x 43 cm for a posteroanterior view), minimizing scatter and unnecessary exposure to surrounding tissues. The attenuated X-ray beam, after passing through the patient's , is captured by a detector: traditional analog systems use film-screen combinations, while modern digital systems employ flat-panel detectors (either indirect conversion with scintillators like cesium iodide or direct conversion with materials such as amorphous selenium) or computed radiography plates with storage phosphors. The central ray is aligned perpendicular to the detector to ensure accurate projection. Key technical parameters govern the quality and safety of the image. Kilovoltage peak (kVp) typically ranges from 100 to 125 for chest to achieve sufficient penetration through air-filled lungs while maintaining contrast; higher kVp values increase beam , reduce absorption in , and lower the required dose but decrease image contrast. Milliampere-seconds (mAs), the product of tube current and exposure time, controls the quantity of X-rays produced and is usually set at 2-8 mAs for an average chest, adjusting for patient size to optimize density without overexposure. An , often with a of 10:1 to 12:1 and at least 103 lines per inch, is routinely used in adult chest to absorb scattered photons and enhance contrast by reducing fogging. Radiation exposure in chest radiography adheres to the ALARA (As Low As Reasonably Achievable) principle, which emphasizes minimizing dose while preserving diagnostic utility through optimized protocols, shielding, and equipment calibration. The typical effective dose for a single posteroanterior chest view is approximately 0.02 mSv (range 0.01-0.04 mSv), equivalent to about 1-5 days of natural (global average ~2.4 mSv annually; ~3 mSv in the U.S.). This low dose reflects the high inherent sensitivity of chest imaging to X-rays due to low tissue , with variations depending on patient habitus and technique. Digital radiography differs from analog systems primarily in detection and capabilities, enabling post-acquisition enhancements that improve interpretability without additional exposure. Analog film-screen relies on fixed chemical with limited (1:40), often requiring repeats for suboptimal exposures, whereas digital systems offer a wider (1:100 to 1:1000), allowing adjustments to contrast, , and tailored to chest structures like pulmonary vessels. This post-processing reduces the need for retakes, further supporting dose reduction, and facilitates integration with picture archiving and communication systems (PACS) for efficient storage and retrieval.

Projections and Views

Standard Views

The standard routine chest radiograph typically consists of posteroanterior (PA) and lateral projections, providing comprehensive frontal and side views of the thorax. The posteroanterior (PA) view is the primary standard projection in chest radiography, where the x-ray beam passes from the posterior to the anterior aspect of the patient, who stands upright facing the image receptor with hands on hips or hugging the receptor to rotate shoulders forward and depress scapulae away from lung fields. This positioning minimizes magnification of cardiac and mediastinal structures, providing accurate assessment of heart size (typically less than half the thoracic diameter) and clear visualization of lung fields during suspended full inspiration, which allows visualization of at least 10 posterior ribs. The anteroposterior (AP) view serves as an alternative projection when upright positioning is not feasible, such as in portable bedside imaging for critically ill patients, with the x-ray beam directed from anterior to posterior while the patient sits or stands with back against the receptor and hands at sides. This approach, however, increases the object-to-image distance for the heart, resulting in magnification of the cardiac shadow (up to 15-20% larger than in PA views) and potential distortion of lung bases due to beam divergence and shorter source-to-image distances often used in portable setups. The lateral view, typically acquired as a left profile with the patient standing or , provides a sagittal perspective that is essential for evaluating the retrosternal and retrocardiac spaces, which are superimposed on frontal projections. This projection aids in assessing hilar overlap and clarifying the position of abnormalities relative to mediastinal contours, such as distinguishing anterior from posterior lesions. It is particularly valuable for delineating the retrosternal clear space and retrocardiac silhouette, where deviations in lucency can indicate underlying . Exposure and quality criteria for standard chest views emphasize proper centering at the T4 vertebral level to ensure symmetric visualization of the , with a source-to-image of 72 inches (183 cm) to reduce magnification and improve sharpness of pulmonary vasculature and mediastinal contours. Collimation should limit the field to 5 cm above the shoulders, to the 12th rib inferiorly, and to the lateral skin margins, using high kVp (100-110) techniques to penetrate mediastinal structures while maintaining contrast in lung fields. Optimal images demonstrate no rotation (symmetric clavicle distances from spinous processes), full inspiration without patient motion, and clear demarcation of diaphragmatic domes.

Supplemental Views

Supplemental views in chest radiography are additional projections employed to address specific diagnostic queries or to resolve ambiguities identified on standard posteroanterior (PA) or anteroposterior (AP) views, enhancing visualization of obscured structures without routinely supplanting primary imaging. The lordotic view, a supplemental projection for apical evaluation, involves the patient leaning backward at approximately 45 degrees with the upper back, shoulders, and head against the receptor while arching the back to project the clavicles and first ribs above the lung apices. This technique enhances visualization of upper lobe pathology, such as tumors or , that may be obscured by overlying bony structures in standard PA or AP views. Oblique views involve rotating the patient approximately 45 degrees from the frontal plane, either anteriorly or posteriorly, to project structures away from overlap and improve diagnostic yield in targeted scenarios. Anterior oblique positioning is commonly used to isolate the axillary portions of the , facilitating the detection of fractures that may be obscured on standard views. Posterior oblique views similarly separate superimposed thoracic elements, such as or pulmonary opacities, allowing better characterization of potential injuries or abnormalities. Decubitus views position the patient lying on their side—right lateral decubitus for the left side or left lateral decubitus for the right—to leverage in assessing within the pleural space. This projection is primarily indicated to evaluate free-flowing pleural effusions, as layering fluid becomes apparent along the dependent hemithorax after a brief exposure interval, distinguishing mobile collections from adherent or loculated ones. It also aids in detecting small pneumothoraces by allowing air to rise to the non-dependent side. Fluoroscopic or older tomographic techniques, though rarely utilized in contemporary practice due to advancements in computed tomography, historically supplemented static radiographs for dynamic evaluations, such as assessing diaphragm motion during respiration. Real-time fluoroscopy enables observation of diaphragmatic excursion, particularly in the sniff test maneuver, to identify paradoxical movement indicative of dysfunction. These methods provide functional insights but are largely supplanted by ultrasound or MRI for such purposes. Additional views inherently contribute to cumulative radiation exposure, though increments are typically minimal compared to standard protocols.

Normal Anatomy

Key Anatomical Landmarks

In a normal chest radiograph, the bony structures provide the foundational framework for identifying thoracic anatomy. The clavicles appear as symmetric, curved horizontal bones projecting laterally from the manubrium, positioned superior to the lung apices and serving as reference points for assessing mediastinal widening. The ribs form a series of arched, paired bony structures encircling the thorax; typically, 10 posterior ribs are visible above the diaphragm on adequate inspiration, with the posterior aspects more clearly delineated due to their alignment with the spine. The thoracic spine is seen as a central, vertical column of vertebral bodies and intervertebral spaces, appearing more radiolucent inferiorly on lateral projections due to overlying lung tissue. The scapulae are superimposed over the upper lung fields as irregular, triangular bony shadows, with their medial borders often distinguishable from adjacent pleural lines. Soft tissue landmarks delineate the mediastinal and diaphragmatic contours. The heart borders are formed by the right atrium on the right side, presenting a smooth vertical interface, and the left ventricle on the left, contributing to the cardiomediastinal silhouette that occupies less than half the thoracic diameter at the level of the diaphragm. The diaphragm domes appear as smooth, upward-curving structures, with the right dome positioned slightly higher than the left due to the underlying liver, both sharply defined against the aerated lung bases. The trachea is visible as a midline radiolucent column descending from the thoracic inlet, bifurcating at the carina—typically at the level of the T4-T5 vertebrae—where it divides into the main bronchi, observable as a subtle Y-shaped junction on lateral views. The lungs are divided into zones corresponding to the lobes, facilitating zonal assessment of parenchymal patterns. The upper lobes occupy the apical regions above the horizontal fissure on the right and the oblique fissure on the left, showing finer vascular markings peripherally; the middle lobe on the right and lingula on the left lie medially between the fissures, adjacent to the heart border; the lower lobes fill the basal areas below the fissures, extending to the diaphragm with more prominent vascularity. The hila, located centrally at the lung roots, contain the pulmonary arteries and veins branching into the lung parenchyma; the left hilum is typically higher than the right, both appearing as well-defined, convex densities with smooth margins on posteroanterior views. Vascular structures outline the great vessels within the . The is visualized as a prominent, curvilinear left superior mediastinal contour, arching over the left main before descending. The appears as a vertical, soft-tissue density paralleling the left side of the spine, posterior to the heart on lateral projections. The is seen as a right superior mediastinal vertical structure, draining into the right atrium and forming a smooth interface with the right heart border. These landmarks are primarily evaluated on standard posteroanterior and lateral projections for optimal visualization.

Systematic Interpretation Approach

A systematic interpretation approach ensures consistent evaluation of chest radiographs by radiologists and clinicians, minimizing errors through structured assessment of image quality and anatomical regions. One widely adopted framework is the ABCDE method, adapted from trauma assessment protocols, which guides reviewers to evaluate key components sequentially. In the ABCDE method, the process begins with A: Airway, assessing tracheal alignment (typically midline or slightly to the right) and patency from the to the carina, noting any deviation or narrowing that could indicate or obstruction. Next, B: involves examining the fields for , opacities, and overall expansion, ensuring clear visualization of the lung zones and pleural spaces relative to anatomical landmarks such as the hila and fissures. C: Circulation focuses on the heart size (cardiothoracic ratio ideally less than 0.5 on posteroanterior views) and vascular markings, checking for mediastinal widening or pulmonary vascular congestion. D: evaluates bones and soft tissues, including , clavicles, spine, and surrounding structures for fractures, densities, or asymmetries. Finally, E: Exposure confirms full visualization of the lung fields, including apices and costophrenic angles, to avoid truncation of findings. Prior to detailed analysis, image quality must be assessed using checklists to determine adequacy. Adequate inspiration is indicated by visualization of at least 6 anterior ribs or 9-10 posterior ribs above the diaphragm, preventing underinflation that could simulate . is evaluated by ensuring spinous processes align midway between the medial ends of the clavicles, as misalignment can distort mediastinal contours. Penetration is sufficient if vascular markings are visible to the peripheral lung zones and vertebral disc spaces are faintly discernible through the cardiac silhouette, avoiding over- or under-exposure that obscures subtle details. Common pitfalls include overlooking subtle asymmetries in lung density or due to perceptual errors, which can be mitigated by adhering to the systematic method. Comparison with prior images is essential, as it enhances detection of interval changes, such as evolving opacities or device migrations, reducing diagnostic misses in serial evaluations. Picture Archiving and Communication Systems (PACS) and digital tools play a crucial role in modern interpretation by enabling of regions of interest, windowing adjustments for contrast optimization, and side-by-side with priors, thereby improving accuracy and efficiency in detecting fine details without additional .

Pathological Findings

Nodules and Masses

In chest radiography, a pulmonary nodule is defined as a well-circumscribed, rounded opacity measuring up to 3 cm in diameter, surrounded by aerated , while a mass exceeds 3 cm and may obscure adjacent structures. These opacities appear as discrete densities within the fields, often detected incidentally during routine . Nodules and masses can be solitary or multiple, with characteristics such as margin definition, internal features, and location providing clues to their ; for instance, spiculated or irregular margins suggest , whereas smooth, well-defined borders are more typical of benign lesions. Calcification patterns within the nodule—such as central, laminated, or popcorn types—favor benignity, often indicating prior granulomatous or , while (a gas-filled cavity within the lesion) may occur in both benign (e.g., ) and malignant processes but requires further evaluation. Pulmonary nodules are an uncommon incidental finding on chest radiographs, with reported frequencies of approximately 0.1-0.2% in general populations undergoing imaging for various reasons. In higher-risk screening contexts using CT, such as those evaluating for or , the detection rate can approach 10% or more, underscoring their prevalence as a diagnostic challenge. The distinguishes benign from malignant causes: benign nodules include hamartomas (often with fat or popcorn ) and granulomas (from infections like or , frequently calcified), while malignant ones encompass primary lung carcinomas (e.g., or squamous cell) and metastases from extrathoracic primaries like or colon cancer. Growth rate assessment via serial chest radiographs is crucial for characterization, particularly for larger nodules (>1.5-2 cm), where a volume of 30-400 days suggests , though smaller lesions often require computed tomography (CT) for precise measurement due to radiographic limitations. Management of nodules detected on chest radiographs follows size-based guidelines adapted from expert consensus, such as those from the Fleischner Society, which primarily address incidental CT findings but inform radiographic follow-up. For low-risk patients with nodules <6 mm, no routine follow-up is typically recommended unless high-risk features are present; nodules 6-8 mm warrant optional CT at 6-12 months, while those >8 mm or with suspicious morphology (e.g., spiculation) prompt immediate CT evaluation or . The American College of Chest Physicians (ACCP) guidelines emphasize reviewing prior radiographs for stability before advancing to CT, as stable nodules over two years are likely benign with >95% certainty. Supplemental views, such as lateral projections, may aid in localizing nodules relative to fissures or hila to refine the differential. Overall, while chest radiography excels at initial detection, confirmatory imaging with CT is essential for most cases to guide risk stratification and intervention.

Cavitary Lesions

Cavitary lesions on chest radiographs appear as lucent, gas-filled spaces surrounded by a wall, typically within areas of or mass, distinguishing them from solid nodules or cysts by their hollow nature. The wall thickness is a key radiographic feature: thin-walled cavities (≤4 mm) are often benign, seen in conditions like bullae or chronic infections such as , while thick-walled cavities (>4 mm, particularly >15 mm) more commonly indicate infection or , with studies showing 94% of thin-walled lesions as nonmalignant and 90% of thick-walled ones as malignant. Common etiologies include infectious processes, such as necrotizing pneumonia from bacteria like or , fungal infections including (a mycetoma within a preexisting cavity), and , which causes in 30-50% of cases. Malignant causes, particularly of the lung (with in 7-11% of primary tumors) and metastatic lesions (4% cavitation rate), often present with irregular, thick walls. Vascular etiologies, such as pulmonary infarction from , account for 2.7-7% of cavities and typically show peripheral location. Associated radiographic signs include air-fluid levels, visible in upright views within cavities due to layering of fluid or pus, as seen in abscesses or aspergillomas, and surrounding parenchymal consolidation or opacification, which is frequent in infectious causes like or . Diagnostic clues on chest radiographs involve lesion location—upper lobe predominance suggesting or post-primary infections—and multiplicity, where multiple cavities may indicate septic emboli, disseminated fungal disease, or metastases. Standard posteroanterior and lateral views are essential for projecting cavities and assessing these features.

Pleural Abnormalities

Pleural abnormalities on chest radiographs encompass deviations in the pleural space, such as accumulations of fluid, air, or fibrotic changes, which can alter the normal appearance of the lung margins and costophrenic angles. These findings are crucial for identifying conditions like effusions, pneumothoraces, and thickenings, often requiring correlation with clinical history for accurate diagnosis. Pleural Effusion
A appears as an opacity in the dependent portions of the on upright posteroanterior chest radiographs, with blunting of the costophrenic angles being an early sign detectable with as little as 175-200 mL of fluid. The classic meniscus sign, characterized by a curved upper border of the fluid higher laterally than medially, indicates a more substantial effusion exceeding 200 mL and helps distinguish it from other opacities. On lateral decubitus views, layering of the fluid confirms the presence of free-flowing effusion, allowing detection of smaller volumes as low as 50 mL, which may not be apparent on standard views. Effusions are quantified as small (less than 200 mL, often subpulmonic or minimal blunting) or large (greater than 500 mL, causing significant hemithorax opacification), though provides superior accuracy for volume estimation compared to , with correlation coefficients of r=0.80 for sonography versus r=0.47 for chest . Pneumothorax
Pneumothorax is identified by the presence of a thin, sharp visceral pleural line parallel to the chest wall, separated by a lucent area devoid of markings, indicating air in the pleural space. This line is most conspicuous apically on upright inspiratory radiographs, with the absence of vascular markings beyond it confirming the ; small pneumothoraces may measure 2-3 cm at the apex. In tension pneumothorax, a life-threatening variant, the pneumothorax causes complete collapse and mediastinal shift toward the contralateral side, often with deep sulcus sign at the costophrenic angle on views. Supplemental expiratory views can enhance visibility of small pneumothoraces by reducing volume. Pleural Thickening
Pleural thickening manifests as irregular or linear opacities along the chest wall or diaphragm, resulting from due to prior , , or hemorrhage. In exposure, characteristic bilateral pleural plaques appear as discrete, calcified or non-calcified areas of parietal pleural thickening, typically dome-shaped and localized to the posterolateral chest wall or diaphragmatic surfaces, without involving the . Diffuse pleural thickening, often encasing more than a quarter of the chest wall, blunts costophrenic angles and may stem from resolved effusions or chronic , distinguishing it from focal plaques. These changes are usually but serve as markers of prior exposure or injury.

Diffuse Lung Patterns

Diffuse lung patterns on chest radiographs refer to bilateral, symmetric opacities that suggest widespread involvement of the pulmonary or alveoli, often indicating underlying or alveolar diseases. These patterns are characterized by hazy or structured abnormalities that obscure normal markings without forming discrete focal lesions. Recognition of these patterns is essential for initial , though they are nonspecific and require correlation with clinical history and further . The main radiographic patterns include reticular, nodular, and alveolar types. A reticular pattern appears as a fine or coarse network of linear opacities diffusely across the lungs, resulting from thickening of interstitial structures such as septa or fibrosis; common causes include or (IPF). In congestive , this may manifest with Kerley B lines, short horizontal lines perpendicular to the pleural surface at the lung bases, representing engorged interlobular septa. A nodular pattern consists of multiple small, uniform opacities, often miliary in size (1-3 mm), seen in conditions like or , where nodules arise from hematogenous dissemination or granulomatous inflammation. The alveolar pattern presents as fluffy, ill-defined consolidations with air bronchograms—dark bronchi against opaque lung—typically due to fluid, pus, or protein filling alveoli; examples include from or (ARDS). Distribution of these patterns provides diagnostic clues: basal predominance is common in or IPF, reflecting gravity-dependent involvement; perihilar or central "batwing" distribution suggests cardiogenic ; and random scattering indicates hematogenous processes like miliary tuberculosis. (HRCT) is more sensitive than chest radiography for detecting early interstitial disease, with chest x-rays showing only about 60% sensitivity for fibrotic when HRCT serves as the reference standard. Differentiating acute from chronic patterns aids in narrowing differentials: acute processes, such as or ARDS, evolve rapidly with confluent alveolar opacities over hours to days, often resolving with treatment; chronic conditions like IPF exhibit progressive reticular changes, particularly basally, with in advanced stages. Systematic interpretation, including , enhances detection during routine review.

Vascular and Cardiac Signs

Cardiomegaly on a chest radiograph is assessed using the cardiothoracic ratio (CTR), defined as the maximum transverse of the cardiac divided by the maximum internal of the thoracic cage, measured at the level of the diaphragm on a posteroanterior (PA) view. A CTR greater than 0.5 is considered abnormal and suggestive of , indicating potential cardiac or pericardial pathology. Chamber-specific enlargement can also be identified, such as manifesting as a double density sign on the right heart border or prominence of the left atrial appendage along the left heart border. Vascular abnormalities are evaluated through changes in pulmonary vascularity and aortic contour. Pulmonary plethora, characterized by increased prominence of pulmonary vessels and hazy lung fields, indicates elevated pulmonary blood flow or venous congestion, often seen in conditions like left-to-right shunts or . In contrast, pulmonary oligemia appears as decreased vascular markings with relative radiolucency of the lung fields, a finding associated with reduced pulmonary , such as in (Westermark sign). Aortic aneurysms may present as widening of the aortic knob or mediastinal silhouette, reflecting dilation of the beyond normal dimensions. Rib notching, inferior erosions of the posterior ribs (typically the third to eighth), results from dilated intercostal collateral arteries and is a classic indicator of . Hilar enlargement requires differentiation between vascular and non-vascular causes. The left hilum is normally larger than the right due to the main ; vascular prominence converges with pulmonary vessels, whereas often appears as discrete, lobulated masses without vascular continuity.

Clinical Applications

Diagnostic Uses

Chest radiographs serve as a primary modality in acute diagnostic scenarios, particularly for evaluating patients presenting with respiratory distress in settings. In cases of suspected , chest radiographs are recommended to confirm the presence of consolidation, with guidelines emphasizing their role in identifying lobar or segmental opacities indicative of infection. For pneumothorax following trauma, upright posteroanterior chest radiographs demonstrate high sensitivity exceeding 90% for detecting air in the pleural , enabling rapid intervention such as placement. Similarly, in suspected , initial chest radiographs may reveal indirect signs like unilateral or , guiding further evaluation despite frequent normal findings in up to 50% of confirmed cases. In chronic conditions, chest radiographs aid in assessing structural changes associated with obstructive and restrictive lung diseases. For (COPD), they are valuable for identifying , evidenced by a flattened diaphragm and increased retrosternal , although not diagnostic on their own but useful to exclude alternative pathologies like during exacerbations. In , chest radiographs provide an initial screening tool with approximately 80% sensitivity for detecting fibrotic patterns, prompting escalation to for definitive characterization. As a first-line investigation in the workup of dyspnea, chest radiographs integrate seamlessly into clinical workflows by identifying common cardiopulmonary abnormalities that prompt targeted escalation to computed tomography or magnetic resonance imaging when findings are inconclusive or suggest complex pathology. Abnormal findings on chest radiographs, such as consolidations or vascular congestion, often direct subsequent diagnostic steps. Evidence from major guidelines supports this approach, with the American Thoracic Society and Infectious Diseases Society of America recommending chest radiographs for patients with respiratory symptoms due to their sensitivity greater than 50% for key pathologies like pneumonia and pneumothorax, while the European Respiratory Society highlights their utility in acute respiratory failure despite limitations in specificity.

Screening and Monitoring

Chest radiographs play a key role in population screening programs for (TB) in high-prevalence areas, where they serve as a sensitive initial tool to identify individuals requiring further diagnostic evaluation among high-risk groups such as household contacts and underserved communities. In these settings, chest X-rays are integrated into national screening algorithms to detect active TB cases efficiently, often combined with symptom screening to prioritize confirmatory testing like analysis. For screening among , however, chest radiographs have demonstrated low yield and no significant reduction in mortality, as evidenced by the National Lung Screening Trial (NLST), which compared them to low-dose computed (CT) and found CT superior for early detection in high-risk individuals aged 55-74 with at least 30 pack-years of history. In disease monitoring, chest radiographs are routinely used to assess treatment response in , particularly to track the resolution of following therapy or observation in asymptomatic stage I cases. Serial imaging every 3-6 months helps evaluate disease progression or remission, with radiographic improvement correlating to clinical stability in many patients. Similarly, for patients undergoing for pulmonary metastases from extrathoracic primaries, chest radiographs provide accessible follow-up to monitor size and number, though they are often supplemented by CT for precise response assessment per RECIST criteria. Recommended screening frequencies incorporate chest radiographs for at-risk occupations, such as periodic imaging per OSHA guidelines for workers with exposure, with frequency varying by age and duration of exposure (e.g., every 2–5 years for many over 45 with significant exposure) to detect early signs of or related malignancies as part of occupational health surveillance. In patients at risk for (ILD), chest radiographs have limited utility due to low sensitivity and are not recommended for routine screening or monitoring per 2023 ACR/CHEST guidelines, which conditionally favor pulmonary function tests and high-resolution CT, particularly in those with high-risk features like positive anti-cyclic citrullinated antibodies. Regarding outcomes, chest radiographs offer cost-effectiveness in resource-limited settings for TB screening, with studies in high-burden countries like estimating implementation costs of approximately $600–1,200 per confirmed case when using portable units combined with AI interpretation (as of 2024), making them viable for widespread active case finding. Nonetheless, for early detection, they remain inferior to low-dose CT, as the NLST reported no mortality benefit and higher false-negative rates for small nodules compared to CT's 20% reduction in lung cancer deaths. Nodule follow-up in screening typically adheres to guidelines emphasizing serial imaging intervals based on size and risk.

Limitations and Challenges

Technical Limitations

Chest radiographs, being two-dimensional projections, inherently suffer from overlap and superimposition of anatomical structures, leading to a loss of depth perception and potential obscuration of pathologies. This projectional nature results in the superimposition of overlapping tissues such as the heart, mediastinum, and lungs, which can complicate the visualization of lesions and mimic abnormalities; for instance, anterior structures like the heart appear magnified in anteroposterior (AP) views due to the shorter source-to-detector distance, potentially simulating cardiomegaly or mediastinal widening. Additionally, just under half of the lung area is obscured by overlying structures like ribs, which cover approximately 75% of the lung field and reduce the detectability of nodules or other focal changes. The wide range of X-ray attenuation differences between aerated lungs and denser mediastinal tissues further exacerbates this issue, requiring high local contrast to identify focal lesions that may be hidden by these overlaps. Sensitivity limitations of chest radiographs are particularly pronounced for subtle or early pathological changes, as the modality struggles with low-contrast detection in the presence of anatomic . Small lesions measuring less than 1 cm in are frequently missed, with studies indicating that such tumors are particularly likely to go undetected on standard chest X-rays. Early also poses a challenge, as conventional lacks the resolution to depict fine structural details and subtle contrast differences associated with initial emphysematous changes, making early-stage detection difficult without advanced techniques. These constraints arise from the broad latitude of X-ray transmission through the chest, which can mask low-contrast abnormalities like small pneumothoraces or early lobar collapse. Artifacts represent another key technical drawback, often degrading image quality and introducing diagnostic uncertainty. Motion blur, resulting from patient movement or inadequate breath-holding during exposure, can obscure fine details, particularly in cases of poor inspiratory effort that mimics conditions like . In analog systems, grid lines from anti-scatter grids may appear on the image, further reducing clarity, while scattered radiation contributes to overall degradation. External factors, such as or subcutaneous air, can simulate pathological findings like , complicating interpretation due to these non-anatomic overlays. Equipment variability significantly influences the reliability of chest radiographs, with differences between portable and fixed systems affecting resolution and accuracy. Portable units, typically used in bedside settings, employ shorter source-to-image distances (around 100-150 cm versus 180 cm in fixed posteroanterior setups), leading to greater magnification of structures and lower , which diminishes the ability to resolve fine details. These mobile systems often lack anti-scatter grids, increasing scatter radiation and reducing contrast, especially in high-attenuation regions like the , compared to stationary digital radiography units. Consequently, images from portable equipment exhibit lower overall quality, impacting the detection of subtle abnormalities.

Interpretive Pitfalls and Artifacts

Underpenetration in chest radiographs, often resulting from inadequate exposure settings, can obscure the retrocardiac region, leading to missed opacities or lesions behind the heart that might otherwise be visible on properly exposed images. This pitfall is particularly problematic in portable or bedside radiographs, where technical constraints limit optimal exposure. Similarly, over-rotation of the patient during acquisition can mimic mediastinal asymmetry or unilateral by altering the projection of thoracic structures, causing apparent differences in between the hemithoraces that are not due to disease. Common artifacts further complicate interpretation. Clothing buttons or snaps can project as rounded opacities resembling pulmonary nodules, especially in the upper zones, and may prompt unnecessary follow-up imaging if not recognized. Pacemaker wires, visible as linear densities traversing the mediastinum and heart, can overlap lung fields and simulate vascular abnormalities or fractures if their course is atypical due to lead migration or fracture. Skin folds, particularly in elderly or obese patients, often create curvilinear lucencies that mimic the visceral pleural line of pneumothorax, potentially leading to erroneous interventions such as chest tube placement. Reader bias, including expectation bias from clinical history, influences perception by predisposing interpreters to overemphasize or overlook findings consistent with the provided narrative, such as anticipating consolidation in a febrile patient and missing unrelated artifacts. This cognitive error contributes to a significant portion of interpretive mistakes in chest radiography. To mitigate these pitfalls and artifacts, double-reading protocols, where a second interpreter reviews the radiograph independently, have been shown to detect discrepancies and reduce error rates in clinical settings. Emerging AI aids in the 2020s, such as deep learning models for anomaly detection, assist by flagging potential artifacts or obscured regions with high sensitivity, enhancing accuracy without replacing human oversight. A systematic approach to interpretation can further minimize these issues by standardizing the evaluation process.

Disease Mimics

Extrapulmonary Mimics

Extrapulmonary mimics on chest radiographs refer to normal or pathological structures outside the lungs and pleura that can simulate intrapulmonary abnormalities, leading to potential misinterpretation. These mimics arise from adjacent tissues such as , bones, gastrointestinal organs, and endocrine structures, often requiring careful correlation with clinical and additional imaging to differentiate them from true . In the skin and subcutaneous tissues, nipple shadows are a common mimic of pulmonary nodules, appearing as well-defined, rounded opacities typically in the mid-to-lower lung zones, often bilateral and symmetrical in males or unilateral in females without breast tissue coverage. These shadows result from the density of the nipple and areola projecting over the lung fields, and they can be confirmed by comparison with prior radiographs or by applying markers during imaging. Skin folds, another subcutaneous mimic, can produce curvilinear densities resembling pleural lines or even pneumothorax, particularly in elderly or obese patients where redundant skin creates overlapping shadows that extend beyond the lung margins without associated lung markings. Musculoskeletal structures, particularly the , can also imitate lesions. Healing fractures often form that appears as nodular densities overlying the , mimicking solitary pulmonary nodules or masses, especially if the is recent and the is prominent. These are typically located along the contour and can be distinguished by reviewing serial radiographs showing or by targeted rib views revealing the bony origin. Gastrointestinal conditions like may project as a retrocardiac opacity on chest radiographs, simulating lower lobe consolidation or due to the herniated or bowel loops displacing into the posterior . This appearance often includes an air-fluid level behind the heart, particularly in larger sliding hernias, and is more evident on lateral views where the opacity separates from the diaphragm. Endocrine abnormalities, such as goiter, can cause superior mediastinal widening that mimics or masses encroaching on the lung apices. Substernal extension of the goiter leads to a smooth, convex border along the , potentially with , and is commonly seen in multinodular goiters where the thyroid enlarges inferiorly into the thoracic inlet.

Iatrogenic and Positional Mimics

Iatrogenic mimics on chest radiographs arise from medical interventions, such as device placements or procedures, that produce imaging findings resembling pathological conditions. For instance, malpositioning of an endotracheal tube into the right main bronchus can lead to left collapse, simulating or due to the resultant opacity and volume loss. Similarly, inadvertent placement of a nasogastric tube into the bronchial may cause alveolar filling with contrast or air, mimicking or even through localized lucency. Central venous catheters inserted incorrectly, such as into the pleural space, can result in iatrogenic hydrothorax, appearing as that may be mistaken for or malignancy-related fluid accumulation. Retained surgical materials, including radiopaque or fractured pacemaker leads, often manifest as linear or mass-like densities, potentially imitating foreign bodies, calcified nodules, or vascular anomalies. Intercostal drainage tubes misplaced into the parenchyma can induce or , with radiographic signs of air or fluid collections that confound differentiation from underlying disease progression. These iatrogenic findings underscore the need for correlation with clinical context and device verification, as misinterpretation can prompt unnecessary interventions. For example, epicardial pacing wires left in situ after may project as extraneous linear opacities, resembling retained surgical swabs or unintended emboli. Ventricular assist device cannulae, with their radiopaque profiles, can be confused with misplaced chest drains, leading to erroneous assumptions of pleural . Positional mimics occur due to patient orientation during , altering fluid distribution, organ , and artifact formation to simulate disease. In or anteroposterior (AP) projections, pleural effusions layer posteriorly along the dependent hemithorax, producing a hazy, veiling opacity over the lower fields that mimics parenchymal consolidation, such as or . This contrasts with upright posteroanterior (PA) views, where effusions form a characteristic meniscus sign; in films, the lack of layering reduces specificity and sensitivity, particularly for small effusions. AP views, common in critically ill patients, exaggerate cardiac and mediastinal due to closer source-to-image (typically 3 feet versus 6 feet in PA), falsely elevating the cardiothoracic ratio above 0.5 and mimicking or . Skin fold artifacts, prevalent in supine AP radiographs from skin redundancy or improper cassette positioning, appear as curvilinear lucencies parallel to the chest wall, closely imitating by creating an apparent visceral pleural line. Unlike true , lung markings often cross the apparent line, and the artifact lacks the sharp edge or deep sulcus sign; however, misdiagnosis can lead to iatrogenic complications like unnecessary tube thoracostomy. Supine positioning also promotes —upper lobe vascular prominence due to gravitational blood flow redistribution—which can simulate early or venous hypertension from . Poor inspiratory effort in supine patients further clumps vessels, enhancing this mimicry and obscuring subtle pathologies. Decubitus views or are essential to confirm mobility of fluid or air in resolving these positional ambiguities.

References

  1. https://medlineplus.gov/ency/article/003804.htm
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC8139021/
  3. https://pmc.ncbi.nlm.nih.gov/articles/PMC8453538/
  4. https://my.clevelandclinic.org/health/diagnostics/10228-chest-x-ray
  5. https://www.mayoclinic.org/tests-procedures/chest-x-rays/about/pac-20393494
  6. https://www.radiologyinfo.org/en/info/chestrad
  7. https://radiopaedia.org/articles/radiograph-1?lang=us
  8. https://www.ncbi.nlm.nih.gov/books/NBK564332/
  9. https://www.radiologymasterclass.co.uk/tutorials/physics/x-ray_physics_densities
  10. https://www.physio-pedia.com/Chest_X-Rays
  11. https://pmc.ncbi.nlm.nih.gov/articles/PMC3632825/
  12. https://radiopaedia.org/articles/chest-radiograph?lang=us
  13. https://pmc.ncbi.nlm.nih.gov/articles/PMC8597495/
  14. https://jmvh.org/article/history-of-tuberculosis-part-2-the-sanatoria-and-the-discoveries-of-the-tubercle-bacillus/
  15. https://www.smithsonianmag.com/history/how-marie-curie-brought-x-ray-machines-to-battlefield-180965240/
  16. http://www.mpijournal.org/pdf/2018-SI-01/MPI-2018-SI-01-p56.pdf
  17. https://erj.ersjournals.com/content/49/5/1700364
  18. https://www.xraymedem.com/wp-content/uploads/2022/06/digital-radiography.pdf
  19. https://appliedradiology.com/articles/digital-radiography-the-bottom-line-comparison-of-cr-and-dr-technology
  20. https://www.ncbi.nlm.nih.gov/books/NBK563236/
  21. https://radiopaedia.org/articles/chest-pa-view-1?lang=us
  22. https://www.radiologyinfo.org/en/info/safety-xray
  23. https://hps.org/hpspublications/articles/dosesfrommedicalradiation/
  24. https://www.ncbi.nlm.nih.gov/books/NBK565909/
  25. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2563775/
  26. https://radiopaedia.org/articles/chest-pa-view-1
  27. https://www.ncbi.nlm.nih.gov/books/NBK370/
  28. https://radiopaedia.org/articles/chest-ap-erect-view-1
  29. https://pmc.ncbi.nlm.nih.gov/articles/PMC1168914/
  30. https://radiopaedia.org/articles/paediatric-chest-lateral-view?lang=us
  31. https://radiologykey.com/imaging-the-chest-the-chest-radiograph/
  32. https://quizlet.com/871853498/radiography-positioning-chest-and-chest-special-views-flash-cards/
  33. https://www.auntminnie.com/clinical-news/digital-x-ray/article/15558899/good-positioning-is-key-to-pa-chest-xray-exams
  34. https://radiopaedia.org/articles/chest-ap-lordotic-view-1
  35. https://radiopaedia.org/articles/ribs-ap-oblique-view?lang=us
  36. https://aoao.org/2023/08/16/rib-fractures-review-of-presentation-diagnosis-treatment-and-outcomes/
  37. https://www.auntminnie.com/radiology-education/article/15559318/tips-and-techniques-for-decubitus-and-oblique-chest-xrays
  38. https://radiopaedia.org/articles/chest-lateral-decubitus-view?lang=us
  39. https://pubs.rsna.org/doi/abs/10.1148/rg.322115127
  40. https://radiopaedia.org/articles/sniff-test?lang=us
  41. https://www.bjaed.org/article/S1743-1816(17)30487-0/fulltext
  42. https://geekymedics.com/chest-x-ray-interpretation-a-methodical-approach/
  43. https://www.ncbi.nlm.nih.gov/books/NBK553874/
  44. https://litfl.com/drsabcde-of-cxr-interpretation/
  45. https://journal.chestnet.org/article/S0012-3692(22)04227-1/fulltext
  46. https://ajronline.org/doi/10.2214/ajr.174.3.1740611
  47. https://radiologyassistant.nl/chest/chest-x-ray/basic-interpretation
  48. https://www.sciencedirect.com/science/article/pii/S0899707122001887
  49. https://radiopaedia.org/articles/pulmonary-nodule-1?lang=us
  50. https://radiologyassistant.nl/chest/solitary-pulmonary-nodule/benign-versus-malignant
  51. https://radiopaedia.org/articles/benign-vs-malignant-pulmonary-nodule-1?lang=us
  52. https://publications.ersnet.org/content/erj/60/suppl66/4308
  53. https://www.aafp.org/pubs/afp/issues/2023/0300/pulmonary-nodules.html
  54. https://pmc.ncbi.nlm.nih.gov/articles/PMC2292573/
  55. https://pmc.ncbi.nlm.nih.gov/articles/PMC3490124/
  56. https://pmc.ncbi.nlm.nih.gov/articles/PMC6100641/
  57. https://www.sciencedirect.com/science/article/pii/S0954611117300331
  58. https://pubs.rsna.org/doi/abs/10.1148/rg.230079
  59. https://www.ncbi.nlm.nih.gov/books/NBK448189/
  60. https://pubs.rsna.org/doi/10.1148/radiology.191.3.8184046
  61. https://www.ncbi.nlm.nih.gov/books/NBK441885/
  62. https://pmc.ncbi.nlm.nih.gov/articles/PMC558461/
  63. https://ajronline.org/doi/full/10.2214/ajr.168.3.9057548
  64. https://pmc.ncbi.nlm.nih.gov/articles/PMC5873627/
  65. https://ajronline.org/doi/10.2214/ajr.144.1.9
  66. https://radiologyassistant.nl/chest/chest-x-ray/lung-disease
  67. https://radiopaedia.org/articles/reticular-and-linear-pulmonary-opacification?lang=us
  68. https://pmc.ncbi.nlm.nih.gov/articles/PMC7122967/
  69. https://pmc.ncbi.nlm.nih.gov/articles/PMC9667806/
  70. https://pmc.ncbi.nlm.nih.gov/articles/PMC8125954/
  71. https://pmc.ncbi.nlm.nih.gov/articles/PMC8807667/
  72. https://www.ncbi.nlm.nih.gov/books/NBK355/
  73. https://pmc.ncbi.nlm.nih.gov/articles/PMC12337967/
  74. https://www.ahajournals.org/doi/full/10.1161/CIRCIMAGING.118.007918
  75. https://ajronline.org/doi/10.2214/ajr.140.5.887
  76. https://pmc.ncbi.nlm.nih.gov/articles/PMC10878208/
  77. https://www.acr.org/Data-Science-and-Informatics/AI-in-Your-Practice/AI-Use-Cases/Use-Cases/Tuberculosis-Screening
  78. https://www.nejm.org/doi/full/10.1056/NEJMoa1102873
  79. https://www.brit-thoracic.org.uk/document-library/clinical-statements/sarcoidosis/bts-sarcoidosis-clinical-statement/
  80. https://pmc.ncbi.nlm.nih.gov/articles/PMC8589876/
  81. https://emedicine.medscape.com/article/358090-overview
  82. https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.1001
  83. https://acrjournals.onlinelibrary.wiley.com/doi/full/10.1002/art.42861
  84. https://journals.plos.org/digitalhealth/article?id=10.1371/journal.pdig.0000894
  85. https://www.uspreventiveservicestaskforce.org/uspstf/recommendation/lung-cancer-screening
  86. https://radiologykey.com/1-technical-considerations/
  87. https://pmc.ncbi.nlm.nih.gov/articles/PMC2516181/
  88. https://pmc.ncbi.nlm.nih.gov/articles/PMC6805164/
  89. https://pmc.ncbi.nlm.nih.gov/articles/PMC4084497/
  90. https://radiologykey.com/chest-11/
  91. https://www.radiologymasterclass.co.uk/tutorials/chest/chest_quality/chest_xray_quality_rotation
  92. https://radiopaedia.org/cases/button-artifact-chest-x-ray
  93. https://pubs.rsna.org/doi/10.1148/radiol.241911
  94. https://radiopaedia.org/articles/skinfold-artifact-1
  95. https://pmc.ncbi.nlm.nih.gov/articles/PMC5790309/
  96. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2810195
  97. https://pubmed.ncbi.nlm.nih.gov/38466390/
  98. https://pmc.ncbi.nlm.nih.gov/articles/PMC3507065/
  99. https://pmc.ncbi.nlm.nih.gov/articles/PMC7735879/
  100. https://pmc.ncbi.nlm.nih.gov/articles/PMC9645508/
  101. https://pmc.ncbi.nlm.nih.gov/articles/PMC10184715/
  102. https://learningradiology.com/notes/bonenotes/healingribfxs.htm
  103. https://pmc.ncbi.nlm.nih.gov/articles/PMC10114023/
  104. https://pubmed.ncbi.nlm.nih.gov/2941430/
  105. https://pmc.ncbi.nlm.nih.gov/articles/PMC4008274/
  106. https://pmc.ncbi.nlm.nih.gov/articles/PMC3920355/
  107. https://www.ncbi.nlm.nih.gov/books/NBK557416/
  108. https://pmc.ncbi.nlm.nih.gov/articles/PMC6837827/
  109. https://pmc.ncbi.nlm.nih.gov/articles/PMC8299512/
  110. https://ajronline.org/doi/10.2214/ajr.148.4.681
  111. https://pmc.ncbi.nlm.nih.gov/articles/PMC11309166/
Add your contribution
Related Hubs
User Avatar
No comments yet.