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Film Critique - Part 1: Chest

Discussion of the diagnostic criteria for routine chest x-rays with emphasis on exposure technique, positioning, pathology, and clinical correlation.

Author: Nicholas Joseph Jr. RT(R) B.S. M.S

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Radiographic Film Critique of the Chest

Written by Nicholas Joseph Jr. RT(R)(CT) B.S. M.S

Article Navigation:ObjectivesIntroductionAnatomy of the Respiratory TractImaging ConsiderationsChest X-ray AnatomyPA/AP Chest RadiographCritique AP/PA Chest RadiographsLeft Lateral Chest RadiographDiagnostic Criteria for the Lateral Chest RadiographSummary PointsReferencesTake TestBottomTo the topTo the bottomObjectives:

Upon completion, the reader should be able to:

Discuss the functions of the respiratory system and describe and identify the anatomical components of the respiratory system.

Distinguish between restrictive and obstructive pulmonary disease and give examples of each.

Discuss the gross structure of the lungs and arrangement and significance of thoracic serous membranes.

Define compliance, elasticity, and surface tension and explain how they affect lung function. State the different types of chest studies performed in radiology and the value of each. Discuss and give examples of soft tissue structures of the chest and bony structures of the chest.

Discuss various chest tubes, catheters, and vascular access lines seen on the chest x-ray.

Identify the anatomy of the chest on AP/PA and lateral chest x-rays.

Describe how to position the patient, image receptor, and central ray for the PA and lateral chest x-rays.

State what structures should be included on the PA and lateral chest radiographs.

State the diagnostic criteria for the PA/AP and lateral chest views.

State what should be seen on a properly made lateral chest radiograph.

State why artifacts should be removed from a chest x-ray whenever it is appropriate.

State the proper range of kVp used for the erect PA and lateral chest x-ray, and tell what structures will be demonstrated.

Discuss the positioning of the cassette in the lengthwise vs. crosswise position for imaging the chest.

State why a 72 inch SID is the standard distance for imaging the chest.

Discuss what structures are demonstrated on the PA chest x-ray when the patient has taken a full inspiration.

Discuss how to determine when there is full inspiration on the PA and lateral chest radiographs.

Discuss the role of kilovoltage (kVp) in providing low contrast chest images.

Determine what changes are needed to correct radiographs that do not meet the diagnostic criteria for the PA or lateral view of the chest.

To the topTo the bottomIntroduction

Radiographic imaging of the chest, especially the lungs is one of the most common types of radiographs taken. The routine chest x-ray provides information about the bony frame of the thoracic cavity, its soft tissues, the mediastinum, and the lung parenchyma. There are many reasons chest x-rays are ordered by physicians, for examples, persistent fever and cough, pneumonia, trauma, pleural effusion, pacemaker or central venous line placement and many others. Because of the many potential diagnoses possible from the screening chest radiograph the radiographer must have a good understanding of what is in question when taking it. When serial radiographs are taken, the radiologist relies on consistent exposure techniques to evaluate progress of clinical treatments. The technologist encounters various types of pathologies that may be harder to penetrate than normal lung, for example, fluid in the thorax, or a dense mass that may require an increase in exposure. Likewise conditions that trap air in the lung, such as emphysema and chronic obstructive pulmonary disease (COPD) require a decrease in exposure factors. Often patients having repeat exams are imaged by different technologists so that consistency in exposure is difficult to achieve without standardized exposure factors. Consider a request to evaluate placement of a central venous catheter that should be in the superior vena cava. The technologist should note the entry site as part of the preparation for performing the test. Clearing metal such as electrocardiogram leads or snaps on the patients gown is important to avoid possible artifact superimposition. Post procedural reasons for ordering a chest radiograph may include checking the placement of a chest tube or locating a central venous catheter tip. The point here is that the technologist must know why a radiograph is taken in order to satisfy the diagnostic criteria for the requested study. To illustrate this point, consider a request for a portable chest x-ray for PIC line placement. The technologist may take an otherwise diagnostically acceptable radiograph of the lungs, but not properly demonstrate the distal tip of the PIC catheter. This is because it may require overexposure of the lung parenchyma or use of a grid during portable imaging to reduce image fog and improve subject detail. What is different about film critique of the chest is that the diagnostic standard for imaging is dependent not only on routine imaging criteria, but also on clinical information provided by the ordering physician. In this module we will explore some common reasons for taking a routine chest x-ray. Keep in mind that while the diagnostic criteria for each view will be stated, the actual diagnostic criteria must also include proper exposure to demonstrate the requested diagnosis. This review of chest imaging will include pathology considerations since different types of pathology require change in exposure technique relative to normal lung tissue. But before we get into these more advanced points of imaging, lets review some basic anatomy of the lungs relative to diagnostic radiography.

To the topTo the bottomAnatomy of the Respiratory Tract

The respiratory system is anatomically divided into upper and lower divisions. Functionally the respiratory system is divided into a conducting airway that moves air into and out of the lungs, and the respiratory division where gases are exchanged between the blood and the airway. Respiration is a term that is often misused in that it refers to three distinct functions of the respiratory system: ventilation, gas exchange, and oxygen utilization. Ventilation or breathing is a mechanical process that moves gases, specifically oxygen and carbon dioxide, in and out of the lungs. Gases move from a volume of high concentration to a volume of low concentration by a passive process called diffusion. Oxygen is highly concentrated in the atmosphere relative to its low concentration in the pulmonary artery distribution in the lungs. Likewise, carbon dioxide is highly concentrated in blood moving through the lungs comparative to air in the alveoli. As a result, oxygen moves from air to blood and carbon dioxide from blood to air down their concentration gradients. Proper gas exchange results in oxygenation of blood and exhalation of carbon dioxide. Therefore, the respiratory system is responsible for delivering deoxygenated blood to the lungs where it is oxygenated returning it to the heart by the four pulmonary veins for systemic distribution by the aorta.

The respiratory system is arbitrarily divided into the conducting and respiratory divisions. The major parts of the respiratory system in order from proximal to distal are the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli. The conducting division includes those passages and cavities that deliver air to the respiratory division. The respiratory division is responsible for gas exchange between the blood and air. Ultimately, lung function is to supply oxygen to the bodys tissues for cellular respiration and remove cellular waste in the form of carbon dioxide gas through expiration. Cellular respiration on the other hand, is a process by which small soluble food molecules are chemically oxidized to release energy in the form of adenosine triphosphate (ATP). The human body only uses carbohydrates, proteins, and fats (lipids) for food. As you may recall, using carbohydrates as a model, glucose when broken down without oxygen generates only 2 energy molecules (ATP) through glycolysis. In the presence of oxygen, Krebss cycle occurring in the mitochondria of cells can generate 36 energy molecules per glucose molecule. Thus oxygen is necessary at the cell level for maximum energy production. Certain disease states like asthma, chronic obstructive pulmonary disease (COPD), smoking and other destructive lung pathologies reduce oxygen to the body and can cause a decrease in energy production.

Though we will not fully discuss the upper division of the respiratory system some of its members should be mentioned. The nose serves as an air passageway. Here the process of warming air begins. Cilia and mucous membranes lining the nasal cavity trap inhaled dust, bacteria and other foreign materials such as pollen and pollutants. The nose contains olfactory receptors that distinguish various odors and contribute to taste. It also functions in adding quality to voice and phonation. The palatine bones separate the nasal and oral cavities. A defect in the palatine bones called a cleft palate is sometimes seen in newborns. This type of defect may allow abnormal communication between the two cavities, but is surgically repairable in most cases.

The pharynx, called the throat in laymens terms, is about 5 inches in length and lies just anterior to the cervical vertebrae. It is arbitrarily divided into three parts, the nasopharynx posterior to the nose, the oropharynx or back of the mouth, and laryngopharynx, which is behind the larynx. The pharynx is continuous with the esophagus having seven opening into it: the right and left auditory (Eustachian) tubes, two openings from the posterior nares into the nasopharynx, the mouth opens to the oropharynx, and openings from the larynx and esophagus. The auditory tubes connect the nasopharynx to the middle-ear cavities functioning to equalize pressure in the middle ear. The nasopharynx contains a collection of lymphoid tissue called the pharyngeal tonsils or adenoids. Posterior to the hard palate is the soft palate containing the uvula. When swallowing the uvula is brought upward to close the nasal pharynx so that food does not enter the respiratory system.

The pharynx or throat is about 5 inches in length and lies just anterior to the cervical vertebrae. It is arbitrarily divided into three parts, the nasopharynx posterior to the nose, the oropharynx or back of the mouth, and laryngopharynx, which is behind the larynx. The pharynx is continuous with the esophagus having seven opening into it: the right and left auditory (Eustachian) tubes, two openings from the posterior nares into the nasopharynx, the mouth opens to the oropharynx, and openings from the larynx and esophagus. The auditory tubes connect the nasopharynx to the middle-ear cavities functioning to equalize pressure in the middle ear. The nasopharynx contains a collection of lymphoid tissue called the pharyngeal tonsils or adenoids. Posterior to the hard palate is the soft palate containing the uvula. When swallowing the uvula is brought upward to close the nasal pharynx so that food does not enter.

The oropharynx begins at the soft palate and extends to the hyoid bone. The laryngeal pharynx continues from the hyoid bone to the larynx becoming continuous with the esophagus. The oropharynx houses the palatine tonsils in its lateral walls and the lingual tonsils on the base of the tongue. The tonsils are accessory structures of the lymphatic system whose functions include filtering circulating lymph. The respiratory and digestive systems become distinct at the laryngeal pharynx. Here food is directed posteriorly into the esophagus and air conduction continues anteriorly into the larynx. Therefore, the functions of the pharynx are a passageway for food and air and by changing its muscular shape aids in phonation.

These sagittal CT images of the upper respiratory tract show the frontal sinus (A), sphenoid sinus (B), nostril (C), nasopharynx (D), oropharynx (E), and nasal conchae (F). The palatine bones that separate the nasal and oral cavities is also seen (yellow arrow). Air is conducted through the nose and oral cavities to the pharynx and larynx. Conduction of air continues from the larynx to the trachea and down the bronchial tree to the alveoli of the lungs. These structures warm, humidify, and clean air of dust particles and heavy debris, conducting it to the respiratory division of the lungs.

The larynx or voice box is the entrance into the lower respiratory system. One of its main functions is to allow air to pass into the trachea and keep food out during swallowing. It also functions in phonation along with the paranasal sinuses and pharynx. It is composed of muscles, ligaments, and cartilage structures. There are nine named cartilages that form the larynx, three are singular and three are paired. The three single cartilages are the thyroid, epiglottis, and cricoid. The three-paired cartilages are the arytenoids, cuneiforms, and corniculates. The most prominent of these cartilages is the thyroid cartilage, commonly called the Adams apple, which is located on the anterior surface of the neck. Its larger size in males is responsible for deeper voice. The epiglottic cartilage is attached to the superior surface of the thyroid cartilage. During swallowing it closes the larynx so that food is directed into the esophagus. During ventilation it opens to allow air to enter or leave the trachea.

These two CT images (left-sagittal, right-3D volume rendered) show various parts of the pharynx and larynx. The larynx (A) and trachea (B) are labeled on both CT images. The pharynx is common to the digestive and respiratory systems, but the larynx is part of the respiratory system only. The larynx continues distally as the trachea and the pharynx is continuous with the esophagus; the trachea lies anterior to the esophagus.

Trachea and Bronchial Tree

The trachea, commonly known as the windpipe is the continuous connection from the larynx to the primary bronchi. It begins at the inferior cricoid cartilage at the level of C5 vertebra extending intrathoracic to the level of T5 vertebra. It is a rigid cartilaginous tube about 12 centimeters length and 2.5 centimeters in diameter. It is composed of 16 to 20C-shaped cartilage rings that open posteriorly. The carina, located at C5 is a reinforcing cartilage plate marking the termination of the trachea as it bifurcates into the right and left primary bronchi. Structurally the cartilage composing the trachea keeps the upper airway open without collapsing during ventilation. The thyroid gland, which is vital to metabolism and growth, lies on the anterior and lateral aspects of the trachea. The esophagus runs posterior to the trachea and anterior to the vertebral column. It is important that the trachea is properly exposed and visualized on the chest x-ray. It should lie in the midline over the lower cervical and upper thoracic vertebrae. Any deviation from the normal anatomical position could represent a mass, pneumothorax, or other pathology. So, it is important that the chest is not rotated when evaluating the trachea.

Cartilage of the trachea and primary bronchi are abnormally calcified, which allows us to see them on these two coronal CT images. Abnormal calcification of the trachea (white arrow) is responsible for tracheal wall detail seen on these images. Bifurcation of the trachea at the carina (yellow arrow) into the left and right main bronchi (blue and purple arrows) is easily seen. The main function of these conducting structures is to move inhaled air to the lungs and remove carbon dioxide released by metabolism into the atmosphere.

The coned down radiograph of the neck seen on the far left shows an air filled trachea (arrowheads). On the same radiograph the trachea is seen bifurcating at the carina (broken line). Calcificified cartilage of the carina (yellow circles) permits its visualization on the two axial CT images. At the carina the trachea bifurcates to become the right and left primary bronchi, which enter the hilum of each lung. The carina is radiographically significant because it marks the level of the pulmonary trunk (red arrow).

The bronchial tree is composed of progressively branching tubes that get smaller distally as they extend into each lung. The first part of the bronchial tree begins where it branches into a right and left primary bronchus. The right primary bronchus is wider and more vertical than the left primary bronchus and therefore more prone to foreign body aspiration. Deeper into the lungs each primary bronchus branches into several secondary bronchi that that branch into multiple segmental (tertiary) bronchi. Tertiary bronchi subdivide into numerous smaller branches (approximately 20 orders) called bronchioles.

The smallest order of the conducting airway is the terminal bronchioles; these end the purely conducting portion of the airway. Distal to the terminal bronchi is where gas exchange occurs. These branches still contain some hyaline cartilage to keep the airway open during inspiration and expiration. Successive branching slows the velocity of inhaled air allowing airborne particles to settle along the tubular pathway. During branching, air is warmed to body temperature and moistened before entering the alveoli. The lumen of the bronchi is lined with epithelium containing cilia (hair like projections from the cells) and mucus secreting cells that traps dust and inhaled particles. Cilia sweep mucus back toward the pharynx where it is either swallowed or expectorated.

This is a volume rendered CT image showing the bronchial tree. In particular, notice its bifurcation into a right and left primary bronchus (blue arrow) that enter the hilum of each lung. The bronchial pathway continues to branch into smaller tubules called bronchioles (yellow arrows) becoming progressively smaller until they reach the terminal bronchioles leading to the alveoli. The smallest branches, the terminal bronchioles are microscopic and are not visible to the naked eye.

Although there is little to no cartilage in the bronchioles, they do contain smooth muscle that allows them to constrict and dilate with thoracic pressure. The respiratory division begins at the respiratory bronchiole, which is immediately distal to the terminal bronchioles. The respiratory division consists of respiratory bronchioles, alveolar duct, alveolar sac, and alveoli. This area of the bronchial tree is called the respiratory division because these structures conduct gas exchange with pulmonary capillaries surrounding them. When air reaches the respiratory division it is clean, moisten, and at a temperature of 37 degrees Celsius. The bulk of each lung is composed of thin walled alveoli, which are the functional units of the lungs. Gas exchange occurs across the respiratory bronchioles down to the alveoli; however, it is the alveoli that conduct most of the gas exchange in the lungs. Thus, the alveoli are the functional units of the lungs and the site where most gas exchange takes place.

This drawing is a representation of the distal branches of the respiratory bronchi where capillaries surround the alveoli. Capillaries (blue, A) release carbon dioxide into the alveolar spaces (C) and absorb oxygen into them to be distributed to the tissues (red, B). The alveoli are the functional units of the respiratory system where the work of gas exchange takes place. The lungs do not carry out its function of gas exchange until after birth when the lungs are expanded. The lung alveoli continue to develop during the first year of life to become the vast network of functional units illustrated in this drawing. The adult lungs have nearly 300 million alveoli, whereas at birth there are a mere 24 million alveoli.

Lung Development

The lungs begin their development from two primary tracheal buds during the 3rd week of gestation. They are not developed sufficiently to sustain birth of an infant until about the 28th week of pregnancy. Underdevelopment is the result of there being no cartilage in the alveoli to keep them open during inspiration and expiration. Alveoli are prevented from collapsing by liquid surface pressure exerted on the walls of the alveoli. Type 2 pneumocytes (pneumocytes are lung cells) begin to appear about the end of the 6th month of development. They secrete a liquid called surfactant that keeps the alveoli open. A failure of the surfactant producing system causes a condition called hyaline membrane disease causing a premature birth to present with respiratory distress syndrome. This is because infant alveoli require low surface tension to remain open during ventilation. Premature birth before the 7th month of development often results in respiratory failure due to inability of the alveoli to remain open during expiration. Type 2 pneumocytes begin to develop during the last trimester of gestation and continue during the few years after birth. At birth there are twenty four million terminal sac and alveoli present. By eight years of age to adulthood there are approximately 300 million alveoli. Therefore, most of lung development occurs after birth. When imaging the infant chest, especially when premature born, it is important that the technologist use proper exposure. Hyaline membrane disease can improve significantly with time so that the serial radiographs must be made on proper inspiration and free of motion artifact.

Left - This infant chest radiograph demonstrates hyaline membrane disease (HMD). Hyaline membrane disease is caused by premature birth with poor lung development. Type 2 pneumocytes are poorly developed causing low surfactant production needed to keep alveoli open. Chest radiograph reveals uniform opacity of the lungs and theair-bronchiogram sign(arrows), characterized by bronchi surrounded by non-aerated alveoli and widespread atelectasis. The infant suffers respiratory distress syndrome, which is treatable including providing satisfactory tissue oxygenation through ventilator support and maintaining proper thermal environment. Right normal infant chest radiograph in which the alveoli are well developed and the lungs are able to aerate properly to supply the bodys needs.

As each lung develops from its lateral primary bud it pushes into a separate coelomic cavity (future pleural cavity). In so doing the lung adheres to the pleural sac becoming surrounded by a double-walled membrane called the pleura. Pleural sacs separate each lung from the other into separate structures that work together. The layer lining the lung is called visceral pleura and the adjacent layer adhering to the thoracic cage is called parietal pleura. Between the parietal and visceral pleura is a very thin space called the pleural cavity. Within the pleural cavity is a small amount of lubricant that reduces friction as the lungs expand and deflate during ventilation. The pleural space is not normally visible except in pathological states like pleural effusion or pneumothorax. Visceral pleura invaginates into the lungs forming fissures that divide the right lung into three lobes and the left lung into two lobes. The right lung has superior, middle, and inferior lobes separated by two deep fissures. Adjacent pleural fissures define lobar boundaries. The right major (oblique) fissure separates upper and middle lobes from lower lobes. A minor fissure separates the anterior portions of the right upper and middle lobes. Thus the lobes on the right are: right upper lobe (RUL), middle lobe (RML), and right lower lobe (RLL). The left lung is divided into superior and inferior lobes by an oblique fissure. Its lobes are abbreviated as left upper lobe (LUL) and left lower lobe (LLL). Accessory lobes such as an azygos lobe or lingual may be present, which are normal anatomical variances.

These two drawing of the right and left lungs are labeled: (A) RUL, (G) horizontal or minor fissure, (D) RML, (E) RLL, (H) oblique or major fissure, (C) RUL, and (J) base of right lung. Labeled portions of the left lung are: (B) LUL, (I) oblique fissure, (F) LLL.

The coronal CT image on the left shows the right minor (horizontal) fissure (white arrow), right major fissure (yellow arrow), and left major (oblique) fissure. These structures are also seen on the right lateral sagittal CT image on the right. The minor fissure separates the right superior lobe from the right middle lobe. The right major fissure separates the right upper and middle lobes from the inferior lobe. The left major fissure (middle CT image) separates the left upper and lower lobes. These fissures are easy to see because this patient suffers significant pleural effusions that fill the pleural space and partially separates the lobes.

These two PA chest radiographs demonstrate normal inflated lungs (left) and a pneumothorax involving the right lung (right radiograph). The pleural space is a potential space between the parietal and visceral pleura with a fluid lubricant between the layers to reduce motion friction. When air is present in the cavity as seen in the right lung on the right radiograph, the lung (arrows) may collapse under pressure. Notice the absence of lung markings throughout the right hemithorax compared to the left hemithorax. Accumulation of fluid in the pleural space is called a hemothorax.

The Mediastinum

Each lung is surrounded by its own pleura separating it from the other lung. The mediastinum is that space between the lungs and pleural surfaces. It covers the area from the sternum anteriorly to the thoracic vertebrae posteriorly. It extends from the thoracic inlet superiorly to the diaphragm inferiorly. There are many structures within the mediastinum including the thymus, heart, trachea, esophagus, thoracic aorta, venae cavae, azygos venous system, pulmonary arteries and veins, lymphatics, and various nerves. All of these structures and their relationships to each other are important. When evaluating the mediastinum it is important that there is symmetry between left and right chest structures on the chest x-ray.

These PA and lateral chest radiographs are presented to show the mediastinum. The anterior view of the chest seen on the left demonstrates the lateral margins of the mediastinum (yellow lines). The lateral view on the right shows: the superior mediastinum labeled (S), which is above the green line; the anterior mediastinum (A), which is that area anterior to the blue line anterior to the heart surface; the posterior mediastinum (P), which is posterior to the purple line and anterior to the thoracic vertebrae. The middle mediastinum (M) is between the blue and purple lines. Components of the mediastinum includes the heart and great vessels, trachea, esophagus, and others structures.

These two 3D CT images show some of the structures within the mediastinum. On the left the sternum (S) is the anterior limit of the mediastinum. On the left the heart (H) lies in the middle mediastinum. Other structures such as the great vessels are seen, however, lymph vessels, pericardium, and other structures are not seen. The sternum is removed on the image on the right to show the entire heart and great vessels that fill the mediastinum. An enlarged mediastinum on chest x-ray could represent enlarged heart, aneurysm, dissection, a mass, or normal anatomy.

To the topTo the bottomImaging Considerations

One of the most commonly performed examinations in radiology departments is the chest x-ray (CXR). While this may seem one of the simplest examinations performed, as we will discuss, is also one of the most repeated exams as well. This is because there are many considerations that must be understood when taking a chest radiograph. The chest x-ray provides information about soft tissue, bone, the mediastinum, pleura, lung tissue, and various types of catheters and tubes that may appear in the lung or heart. Also the technologist must consider the patients position, the projection of the central ray (CR), and exposure factors that make an optimal radiograph. But what makes the chest radiograph so elusive is that often different technologists may perform serial radiographs so that image consistency is often lost. To assure image and diagnostic quality there must be consistency in how the CXR is performed in an imaging department. Ultimately, exposure factors selected, post processing, patient positioning, and pathological conditions can affect the diagnostic quality of a chest radiograph. Understanding those factors that affect image quality is a must in order to achieve consistently high quality serial radiographs.

Selecting correct exposure factors is one of the most important components in the production of quality radiographs. When serial radiographs are taken, for example a daily portable chest x-ray on an intensive care patient, varying exposures may hide or appear to create pathology. Keep in mind that patient position, source-to-image-distance (SID), milliampere/time (mAs), and kilovoltage (kVp) selections all affect the quality of radiographs. Serial radiographs monitoring the effectiveness of treatment regimens are especially sensitive to serial image quality.

The standard positions for chest radiographs are erect posteroanterior (PA) and the left lateral. Each of these positions places the heart closest to the image receptor since it lies anterior and slightly to the left in most individuals. A source- to-image-distance (SID) of 72 inches is also used since this distance reduces magnification of the heart and mediastinum. The central ray enters at the level of the sixth thoracic vertebra. Portable CXR is performed with the central ray directed anteroposterior (AP). The patient is either supine or upright depending on the patients condition. For example, during trauma and the patient is on a spine board due to spine precautions the radiograph may be performed supine. In contrast, to check fluid levels in a patient with known pleural effusions but is unable to transport to the radiology department, the patient should be imaged at bedside in the upright position.

When performing the portable CXR most of the variance between technologists involves patient positioning and SID. For example, indicating that the patient is upright can mean the patient is 45-degrees upright, or 90-degrees upright. There is great inconsistency in the meaning of upright among technologists. Upright should mean the patient is as close to 90-degrees as possible and the horizontal central ray is parallel to the floor. The exposure technique is greatly affected by the SID. Keep in mind that the SID selected is affected by the inverse square law, which describes how radiation intensity is affected by changes in distance. An exposure of 90 kVp at 10 mAs will have different effects when the SID is 40 inches vs. 60 inches. Therefore, the SID should not be estimated, it should be measured for accuracy. In addition, standardization of source-to-image-distance during portable imaging is a must in order to achieve consistent quality serial portable radiographs.

Most adult chest radiographs taken in the radiology department use a fixed kVp of 100 to 140, and vary the mAs using automated exposure, such as phototiming. The average exposure for the adult chest radiograph is about 120 kVp. Thus repeating radiographs because of improper exposure is not the main cause of repeats in the department. However, with portable imaging, the exposure varies between technologists based on patient presentation. The risk of improper exposure increases when two or more imaging factors such as kVp and SID are changed simultaneously. For instance, a previous optimal portable chest radiograph was recorded to be taken using the exposure factors: 92 kVp, 8 mAs, 40 inches SID (exposure 1). The technologist takes a new radiograph at 80 kVp, 10 mAs, 50 SID (exposure 2). The characteristics of these two exposures will be different based on their exposure factors. Exposure 1 will have lower contrast and greater overall density than exposure 2. This is because the kVp of the first exposure gives greater penetrability to the x-ray beam. In fact, the kVp is 15% higher than the second exposure, which is equivalent to doubling the mAs. The SID of the first exposure is 40 inches, which also increases the intensity of the x-ray beam. The second exposure will lack detail and density when compared to the first exposure and may limit the reading of the radiograph. Now, if a third exposure is taken a few days later using 90 kVp, 10 mAs, 40 inches SID (exposure C) the overall results will be much the same as exposure A. This is because the kVp and SID remain fairly constant. Setting department standards for chest imaging, especially those factors that greatly affect the scale of contrast (kVp) and radiation intensity (SID) constant will greatly improve exposure consistency for serial portable radiographs.

Exposure factors such as mAs and kVp should be consistently applied for portable chest imaging just as it is for an upright chest radiograph performed in the imaging department. A good example of consistency is the use of fixed kVp for dedicated stationary chest x-ray units and varying the mAs. This is usually accomplished using automatic exposure controls (AEC) that adjust the mAs to the desired preset image density. The reason it is so important that fixed kVp techniques are used in chest imaging is to produce consistent image contrast. Keep in mind that kVp is the primary controller of contrast. In other words, as kVp increases the number of shades of gray also increases. This is called low contrast or long scale contrast imaging. Likewise, decreasing kVp decreases the number of shades of gray in the image. This is called high contrast or short scale contrast imaging. The points here are that when you decrease the number of densities possible on a radiograph, especially of the chest, any pathology outside the contrast range for the exposure will not be seen. This is why it is recommended that chest radiographs be taken using at least 120 kVp for adults. However, for portable imaging the kVp rarely exceeds 90 kVp because the amount of scatter contributing to image fog is great. Low contrast imaging for the chest is desirable because it yields a greater number of densities on the radiograph and a wider range of diagnoses possible. Keep in mind that initial chest x-rays on hospitalized patients are often performed in the radiology department using high kVp technique. Follow up portable images using lower kVp is acceptable because baseline diagnosis has been established.

For portable chest imaging the kVp rarely exceeds 90 kVp. This is because the amount of scatter radiation that causes image fog increases greatly as the kVp increases. Low contrast imaging of the chest is desirable because it yields a greater number of densities on the radiograph and a wider range of diagnoses possible. Keep in mind that initial chest x-rays on hospitalized patients are often performed in the radiology department with the patient standing and using high kVp technique. Follow up portable images using lower kVp is acceptable because the baseline diagnosis has been established.

Peak kilovoltage used is another important imaging consideration that applies to patients who are not ambulatory and are usually brought to the imaging department for a chest x-ray. Often these patients are unable to stand for imaging against the upright Bucky so they are positioned upright and the cassette placed behind their back for imaging. There is no difference between this imaging style and portable imaging because the kVp is about 30% lower than the optimal 120 to 140 kVp. It is important that the technologist does not merely place a cassette behind the patients back performing a replication of portable imaging. Instead take time to position the patients back against the upright Bucky, or carefully align them to a grid-cassette so high kVp can be used. Notwithstanding, as we see later in this module, the diagnostic criterion for portable chest imaging technique is a compromise between an optimal low contrast exposure and high contrast exposure.

This drawing demonstrates a fundamental difference in what is demonstrated with long scale contrast (top) and short scale contrast (bottom) exposures. When we look at a structure or pathology, which is represented on the drawing by the density at the arrow, it is important to understand that it is only visible if a significant number of x-rays pass through the structure and reach the image receptor. This is dependent on photon energy, which determines penetrating power of the x-ray beam. The energy of the photons in the x-ray beam is a function of the kVp. As the kVp increases, so does the number of radiographic densities displayed. Low kVp demonstrates fewer densities because photons are absorbed and do not reach the image receptor. Photons that do not penetrate the part do not reach the image receptor and will not contribute to the image. When comparing the low contrast scale to the high contrast scale, high contrast will not demonstrate the structure at the arrow if this were pathology. This is why placing a cassette behind the patients back when in the department for an x-ray is not recommended. In department CXR is a higher kVp image than the portable image and is meant to increase the densities on the radiograph when looking for pathology.

For many years film-screen exposure was the standard imaging technology; however, it is also dependent on dynamic film processing conditions. Chemical film processing requires daily quality assurance testing and performance monitoring for accurate image reproducibility. Besides, film exposure is also affected by film speed, screen speed, and manufacturing differences. Processor temperature fluxuations, replenishment rates for developer and fixer solutions, water and dryer temperatures contribute to variable image quality. Automated chemical film processing is now becoming obsolete although it still remains in use in many institutions. Digital imaging and digital processing is the premier technology for quality imaging and consistent imaging results. Technologies like computerized radiography (CR) and direct digital radiography (dDR) produce exceptional contrast and subject detail. Furthermore, soft tissue detail is superior to film-screen radiography.

A digital radiographic image is first formed as an electronic image that is displayed on a grid called a matrix. The image is laid out in rows and columns called an image matrix. Each image is made of thousands, preferably millions of small cells that make up theimage matrix. Each cell in the image matrix is called a picture element, or pixel. With digital imaging, eachpixelwill have a numerical value that determines the brightness (density) or other details of the cell. Each box has its own dynamic range of values according to the number of bytes of processing; this is called agray-scale range. Remember that for one byte there are 256 possible values for the density of each pixel, and with 16 bit processing there are 65,535 possible densities any cell can have. These densities can be correlated with the energy of the photons that strike phosphors in the recording medium from which the image will be reconstructed. So, if we use for example, 16 bit processing, and millions of cells in our matrix, we can have tremendous latitude for exposure and image detail. Using our binary code of 0 and 1 a different density is assigned for each of our 65,535 numbers in our gray scale range. The brightness of the phosphor corresponding to that area covered by each pixel can be assigned.

This digital chest radiograph shows great detail and contrast created by many shades of gray pixel values. On the right is a magnified portion of the radiograph showing many small square pixels. As you can see there are a large number of different densities that make up the digital image. The brightness of pixels can be further manipulated by the radiologist by windowing or leveling the image.

Digital imaging is usually coupled to digital viewing through a picture archiving and communication system (PACS). Images can be manipulated during viewing through a process called windowing and leveling. Window parameters control how light or dark an image is, and level controls the ratio of black to white display, or contrast. An over penetrated radiograph that would otherwise be repeated can within great margins of latitude be adjusted. However, an underpenetrated radiograph may not be darkened or given sufficient contrast to provide diagnostic detail. Optimal kVp range for the adult chest x-ray is 100 to 140, though most PA chest radiographs are still acquired at 120 kVp. Using automated exposure the technologist is able to increase the phototimer density setting using the +1, +2, +3, or +4 setting. Each increase in the phototimer setting is equivalent to about a 25 percent change in the mAs. Thus the exposure can be increased for large patients and decreased (-1, -2, -3, etc.) for a thin patient or those with chronic obstructive pulmonary disease (COPD). High kVp chest images are more accurately manipulated through windowing/leveling processor parameter. Keep in mind throughout our critique that some digital images are evaluated by traditional static film criteria; however, they are not repeated, but are adjusted by the radiologist during interpretation.

To the topTo the bottomChest X-ray Anatomy

An accurately positioned chest x-ray will demonstrate the lung apices, lung bases, medial and lateral lung fields, and the costophrenic angle of each lung. An air filled trachea is seen superimposed in the midline of the upper thoracic vertebrae. The heart silhouette should be seen without rotation and the lower thoracic vertebral bodies slightly transparent through the mediastinum. The PA or AP chest radiograph displays a wide range of structures with many superimpositions having various radiographic densities. Furthermore, overlying mediastinal or bony structures may obscure portions of the lungs. Therefore, it is important that image quality be optimal and positioning accurate for diagnosis of subtle abnormalities. Some of the structures that should be clearly demonstrated are labeled below:

Right clavicle (A), right scapula (B), right fourth anterior rib (C), right eighth rib (D), right costophrenic angle (E), left lung apex (F), aortic arch (G), hilum (H), heart (I), left lung base (J), right hemidiaphragm (white arrow).

The lateral chest view is orthogonal (at 90-degrees) to the PA or AP chest radiograph. It allows for visualization of anterior to posterior structural relationships. The retrocardiac region, especially the left lower lobe and retrodiaphragmatic lung bases are demonstrated. Some detail about the thoracic vertebrae is also seen although there will be superimposed structures on the spine. Accurate positioning and optimum exposure is necessary to demonstrate all structures that are systematic evaluated on the lateral chest radiograph. The proper anatomical positioning for the lateral chest radiograph is seen below and some structures are labeled:

Structures that should be demonstrated on the left lateral chest radiograph include: esophagus (A), trachea (B), lung hili (C), heart silhouette (D), lung apices (E), scapulae (F), thoracic vertebra (G), thoracic intervertebral foramen (H), superimposed posterior ribs (I), costophrenic angles (J), and diaphragm (yellow arrows).

To the topTo the bottomPA/AP Chest Radiograph

There are definable standards by which each chest x-ray projection is evaluated. The diagnostic criteria include patient positioning, exposure technique, structures demonstrated, and proper inspiratory effort. The PA chest x-ray is taken with the patient erect, on full inspiration, patients chin extended out of the lung fields, the scapula rotated out of the field, and if the patient has large breast move them upward and out away from the lungs. When these techniques are employed the chest x-ray will be without rotation and will meet maximum diagnostic evaluation criteria for patient positioning. In addition to accomplishing the diagnostic criteria for chest imaging, certain principles are practiced that reduce patient radiation exposure in keeping with ALARA. Specific practices include use of good collimation and gonadal shielding of all patients, especially those in the reproductive years of life.

It is important that the PA chest radiograph is well penetrated so that peripheral pulmonary vessels are demonstrated; vertebral bodies are seen through the mediastinum, and retrocardiac and retrodiaphragmatic pulmonary vessels are seen. The left lateral should be well penetrated so that the right lung is demonstrated superimposed on the left lung, thoracic vertebral bodies and intervertebral disc spaces are seen, heart and lung densities show good penetration, and bronchial and vascular markings are clearly displayed.

The goals to be accomplished by positioning the patient for the PA chest x-ray is to accurately demonstrate lung pathology, show air-fluid levels when present, and correctly display the mediastinum with minimal magnification. Secondary goals include reducing repeat rate associated with improper collimation, incorrect exposure technique, poor inspiratory effort, and patient motion. Body habitus must be considered when performing the PA chest x-ray. There are four types of body habitus: sthenic, hypersthenic, asthenic, and hyposthenic. The average body type, which is seen in about 50% of the population is the sthenic type. Most technologists do not have any problem positioning this body type because the lungs will fit on a 14 x 17 inch cassette turned lengthwise. The hypersthenic type (5%) presents with a massive broad deep thorax. The lungs are generally short and wide, therefore, these types usually do not fit on the standard 14 X 17 inch cassette or image receptor lengthwise. To avoid clipping the costophrenic angles the cassette is turned crosswise. The asthenic (10%) body type is long and slender. The thorax is narrow in width, shallow in the anteroposterior dimension, and vertically long. It is easy to over collimate the lung fields lengthwise clipping the costophrenic angles. The hyposthenic (35%) body type is close to the average body type; however, care must be taken not to over collimate vertically clipping the costophrenic angles.

The PA chest radiograph on the left was taken of a person having the hyposthenic body type. The right radiograph demonstrates a person having the hypersthenic body type. The image receptor is positioned in the lengthwise position for sthenic, hyposthenic, and asthenic types, but is turned crosswise for hypersthenic body types to avoid clipping the costophrenic angles.

Good inspiration is accomplished by having the patient perform a double ventilation technique. First, the patient inhales followed by exhaling; then the patient is asked to inhale a second time and hold it, which allows them to take in more air to expand the lungs. Taking two inspirations prior to exposure should be rehearsed with the patient to achieve better cooperation. Proper positioning of the image receptor is important because deep inspiration increases the thoracic volume in three dimensions. The vertical dimension increases as the diaphragm contracting downward. The thorax increases in the transverse and anteroposterior diameters as the ribs swing upward and outward. The number of ribs superimposed on the lungs determines the degree of inspiration on the chest x-ray. Good inspiration in the adult will display a minimum of 10 posterior ribs, which are counted at their attachment to the thoracic vertebrae to assure accuracy.

Diagnostic Criteria for PA Erect Chest Radiograph

All potential foreign bodies such as necklaces, body piercings, bra, sequins, and some fashion printed shirts that may cause an artifact should be removed. The patient may be required to change into a gown when clothing is questionable.

All chest radiographs should be made with the patient upright so that the thoracic vertebrae are perpendicular to the central ray.

The CR should be perpendicular to the MSP, a horizontal beam to demonstrate air/fluid levels.

A 72-inch SID should always be used since this decreases magnification of the heart silhouette.

High kVp (100-140) to produce a low contrast image and properly penetrate the lungs and mediastinum. A properly exposed radiograph will demonstrate the vascular lung marking and slight visualization the thoracic vertebral bodies through the heart shadow. The retrocardiac and retrodiaphragmatic pulmonary vessels should also be seen through the heart silhouette.

The PA/AP chest x-ray is taken on deep inspiration filling the trachea and lungs. Inspiration should adequately visualize at least 10 posterior and 8 anterior ribs.

The chest should not be rotated evidenced by symmetry of the sternoclavicular joints. The costophrenic angles must be entirely included. The apices should project about 1 inch above the 1st rib. The scapula should be seen slightly superimposing the ribs.

A position marker, which is usually an arrow indicating upright or supine, and an anatomical marker to indicate left or right side must appear on the radiograph

The photograph on the left shows proper positioning of a patient for the PA chest x-ray. Notice the chin is extended, hands on waist and shoulders rolled forward and downward. The collimated area is limited to the lungs (yellow dotted box). A lead apron drapes the lower abdomen and pelvis (yellow arrow) to protect the gonads. The radiograph on the right shows a properly made PA chest radiograph that meets the diagnostic criteria. It shows low contrast with good penetration of the medial lung fields and thoracic spine. It also shows deep inspiration as 10-11 posterior ribs are seen. Position and anatomical markers are present on the radiograph as required.

The supine or bedside (portable) AP chest radiograph is used when the patient is debilitated, seriously ill, unstable, or in some trauma scenarios. In most cases where the portable supine chest radiograph is taken there will be various factors contributing to acceptance of a less than optimal image. Often it is not possible to remove all radiopaque objects such as monitor leads, life support apparatus, and the like. Keep in mind that the supine AP portable view does offer a quick assessment of the patient, and when properly made can be a sufficient replacement to the upright chest radiograph. The challenges for the technologist are to include the entire lung fields, reduce magnification, limit chest rotation, and penetrate the mediastinum without burnout of the lung markings. Another challenge is to get a deep inspiration free of motion artifact. Being supine often results in poor inspiratory effort, which results in low lung air volume, increased basilar density, and vascular crowding. The supine chest radiograph can present normal anatomy in a way that often mimics congestive heart disease in the elderly as the heart can be significantly magnified.

Diagnostic Criteria for AP Supine Chest Radiograph All potential foreign objects such as necklaces, body piercings, bra, sequins, and some fashion printed shirts that can cause an artifact should be removed. Heart monitor leads, intravenous lines and such that can be moved out of the main lung fields should be moved.

The CR should enter the chest at the level of T7 and perpendicular to the cassette. The patient is often at varying degrees upright rather than truly supine.

Most supine chest projections are performed at 40 to 60 inches SID and the central ray vertical. This will cause the heart to appear magnified.

High kVp (80 to 90) to produce a low contrast image and properly penetrate the lungs and mediastinum is preferred. A properly exposed radiograph will demonstrate the vascular lung marking and slight visualization the thoracic vertebral bodies through the heart shadow. Plural effusion and other pathologies may obstruct visualization of lung markings compared to the erect position.

The radiograph is taken on deep inspiration filling the trachea and lungs. Inspiration should adequately visualize at least 8 posterior ribs. The lungs will appear denser since there is less inspiration than when erect.

The chest should not be rotated evidenced by symmetry of the sternoclavicular joints. The apices and costophrenic angles of the lung bases must be entirely included. The scapula is seen slightly superimposing the ribs.

A position marker, which is usually an arrow indicating supine, and an anatomical marker to indicate left or right side should appear on the radiograph.

Now lets view and critique some radiographs using the diagnostic criteria for the AP/PA projection of the chest.

To the topTo the bottom

Radiograph #1

This patient was unable to get a CT scan because the nurse was unable to get intravenous access. A PICC line was inserted from the right antecubital fossa. Does this AP upright portable radiograph meet the diagnostic criteria for a chest view for PICC line placement?

Critique of Radiograph #1

This radiograph fails the diagnostic criteria for several reasons including artifact in left lower lung field, failure to include both costophrenic angles, and improper exposure technique for demonstrating the PICC line. Although the lungs are not the central focus of this radiograph both costophrenic angles are clipped sufficiently to warrant repeating this film. Note the pen in the pocket on the left lower lobe of the lung field obscures anatomy (red arrow). Removing all metallic objects is required for all x-rays because it could obscure an incidental pathological finding. Had this radiograph been made using screen-film imaging it would have to be repeated because the PICC line is not clearly seen (yellow broken circle-left radiograph). But because of digital imaging the radiograph was windowed for more density and contrast. The magnified portion of the radiograph (right) shows the effect of changing the density with a digital image. The PICC line is seen in the subclavian vein (yellow arrow).

Radiograph #2

This patient complained of chest congestion following 2 days hospitalization. Patient refused to be transported to the radiology department for an upright PA and lateral chest x-ray. Her physician ordered a portable AP CXR instead. Give your critique of this portable upright AP chest radiograph.


It is quite obvious that the patient may be a little uncooperative; however, taking a little time to get cooperation is well worth the final results. The patient is leaning to the right, which slightly alters the anatomy at the lung bases. As a result proper collimation was not applied and both arms are in the field of view. This is not in keeping with the practice of ALARA. The curled wire in the upper part of the chest should have been moved. The exposure technique displays good penetration of the lungs and visualization of lung markings is adequate. All required anatomy is demonstrated on the radiograph. This radiograph is not optimal and should be repeated with the patient straight, artifact removed, and applying good collimation in keeping with ALARA.

Radiograph #3

This PA CXR was taken to evaluate PICC line placement and the lungs for possible pneumothorax. The lung fields are also questioned because of chest congestion complaints. Does this radiograph meet the diagnostic criteria for the PA CXR? Keep in mind that this radiograph is a digital image using a dedicated chest unit.


Again, this is a radiograph that obviously misses the diagnostic criteria for the PA CXR because both lung fields are not included. The right costophrenic angle is clipped; however, before we repeat this radiograph we have to consider two other finding on this radiograph. Notice the PICC line (red broken circle) is seen in the left jugular vein. The area in the red circle is magnified on the right to show the PICC line tip (red arrow). The astute radiographer would not repeat this radiograph since the PICC line needs to be repositioned and the radiograph repeated. So, in keeping with ALARA, repeating this radiograph to show the right lung field would not be necessary. However, when this radiograph is repeated use proper shielding and close collimation to reduce unnecessary exposure to the abdomen.

Radiograph #4

This patients physician requested a portable chest x-ray to evaluate treatment for congestive heart failure and known pleural effusions. What considerations should the technologist make when performing this radiograph, and tell whether or not it meets the diagnostic criteria for the AP upright portable CXR.


The technologist should consider that when serial radiographs of a patient are taken it is important that the radiologist can compare them for improvement related to treatment. Because fluid levels in both lung fields are in question the patient should be brought to a true upright position. Notice that the radiograph is labeled upright, but fluid in the pleural space surrounds the upper part of the left lung field (arrows). As a result, vascular lung markings are obscured. Notice the stomach is distended and does not show fluid levels because the patient is not fully upright. Being supine has also produced low inspiratory effort. This findings confirm the patient is really supine or at an angle less than 45 degrees upright. The exposure technique does not adequately penetrate the lung bases. Serial radiographs to evaluate fluid must be made the same way with good fluid penetrating technique. An increase of 15% kVp would be an adequate exposure. Fluid levels in the chest cannot be assessed and is the main reason this radiograph does not meet the diagnostic standards for the AP portable chest x-ray. Getting the patient upright and the x-ray beam horizontal to the floor will accurately demonstrate fluid in the lungs.

Radiograph #5

The patient history for this portable AP chest x-ray includes pleural effusions bilaterally, chest tube on right, and obesity. Does this radiograph meet the diagnostic criteria? If no, then what could be done to make this an acceptable radiograph?


Again we see an example of the technologist marking the radiograph upright when the anatomical indicators show that the patient is more supine than upright. In particular the stomach, which is filled with air (green arrows), does not show fluid leveling. Also, fluid in the lungs (red arrows) show no leveling as it would if the patient is 90 degrees upright and the x-ray beam directed horizontal to the floor. Although the technologist passed this radiograph it does not meet the diagnostic criteria for the portable AP CXR. This patient has a chest tube (blue arrow) to drain excess fluid; therefore, the patient should be upright for all serial radiographs to assess fluid. The exposure technique does not adequately penetrate the costophrenic angles or display location of chest tube openings draining fluid. Increasing the kVp by 15% will provide adequate exposure. Better collimation could also be used in keeping with ALARA.

Radiograph #6

What is your critique of this upright portable chest radiograph taken to evaluate the lung fields?


This patient is adequately positioned upright position, although the clavicles show asymmetrical with slight rotation to the right. What stand out most about this radiograph is poor collimation and high contrast. Thoracic vertebral bodies are not visualized through the heart silhouette, neither are the retrocardiac vessels clearly seen. The central focus of this radiograph is the central line (yellow arrow), which is faintly seen. A high contrast area in the abdomen (blue asterisk) confirms this is a low kVp exposure. If a patient is large and you need to see the PICC line, use a grid cassette. Taking ones time to position the grid so you can use high kVp technique is well worth the diagnostic quality. Collimation to the lung fields (yellow dotted line) will also improve this view. At most institutions this radiograph would not be repeated; however, it does contain those errors mentioned that should be avoided.

Radiograph #7

This PA upright chest x-ray was taken on an ambulatory patient with a history of shortness of breath, smoker. What is your critique of this radiograph?


Overall, this is an acceptable radiograph. There is some rotation of the chest. The trachea is reasonably midline although the clavicles are not symmetrical. Have the patient stand flush on the floor, shoulder depressed, hands on waist with scapula rolled toward the image receptor. The chin should be over the top of the Bucky with the head straight. These preparations will help align the neck and chest. What could have been done to improve this radiograph is good collimation. Though a chest radiograph is considered low radiation dose compared to a CT scan or fluoroscopy, unnecessary exposure is still of concern. Using a lead shield is also recommended to protect the abdomen during the exposure. These principles are in keeping with ALARA. Otherwise, the exposure technique is adequate for visualizing required anatomy. This radiograph does not need to be repeated because of poor collimation.

Radiograph #8

This radiograph was taken to localize a newly placed PICC line. Does this radiograph meet the diagnostic criteria for the AP chest radiograph?


At first glance this radiograph may appear to meet diagnostic criteria, but with close inspection we see it is grossly underpenetrated and lacks mAs. The lung fields can be evaluated for pneumothorax; however, not being able to see the thoracic vertebral bodies through the heart silhouette indicates low kVp. As for the PICC line (white arrow), it appears to be logged in the left arm vein. The technologist did properly include the medial portion of the left arm. Keep in mind this is a high contrast exposure evidenced by the bright area over the abdomen (yellow arrow). A portion of the arm is magnified and darkened; however, because the exposure lacks mAs and kilovoltage the PICC catheter is not easily seen. This radiograph should be repeated using at least a 15% increase in kVp and possibly an increase in the mAs. Whether or not the catheter should be adjusted and how much cannot be determined from this radiograph.

Radiograph #9

This patient was too sick to stand for their chest x-ray; therefore, the technologist performed an AP upright study with the patient in bed. What is your critique of this radiograph?


Performing a high quality radiograph can be difficult depending on patient presentation. We must always keep in mind that serial radiographs are performed to monitor treatment progress. Therefore, we should put our best effort into each radiograph performed. In this case performing the study with the patient upright, proper alignment of the tube-part-cassette, and increasing the kVp would produce a better radiograph. As for exposure technique, better penetration of the costophrenic angles and demonstrating the retrocardiac lung marking is the diagnostic standard for the chest exposure technique. When the lower thoracic spine is seen through the heart silhouette and the medial left lung is demonstrated, the exposure technique is optimal. This radiograph should be repeated using greater kV to penetrate the lung bases. Correct alignment of the patient is also desirable when this radiograph is repeated. This includes having the CR enter at the level of T6 so that the concentrated part of the beam is over the lower thoracic vertebrae. To get an optimal exposure place the patient against the upright Bucky , use at least 120 kVp, and automated exposure control.

Radiograph #10

Give your critique of AP supine chest x-ray taken on a newborn infant to evaluate lung fields, nasogastric tube, and umbilical line placements?


This is a good radiograph of the infant chest. Notice that the exposure technique adequately penetrates the thoracic vertebrae. The head is straight so that the clavicles are not rotated. When performing a pediatric chest x-ray, it is important that the chest is not rotated. The trachea should appear in the midline over the cervical and upper thoracic vertebrae. A non-rotated chest allows for accurate evaluation of the mediastinum so that the border of the heart and thymus is distinct. Good alignment can help identify anatomical variance due to congenital disorders (e.g. tetrology of fallot, dextrocardia, etc). Proper collimation was applied vertically to include the nasogastric tube (blue arrow) and umbilical catheter (red arrow). Overall, this is an excellently positioned and exposed chest x-ray. Optimally, the proximal portion of the NG tube should have been moved upward out of the field. The left chest lead could have been moved from the lower lung field. Overall, this is a good radiograph that does not need repeating and meets diagnostic standards.

Radiograph #11

This patient was sent to the radiology department for an upright chest x-ray to check progress of treatment for various lung disorders, and to evaluate a newly place PIC catheter. The patient receives continuous oxygen at 8L. What is your assessment of this radiograph?


What is good about this radiograph is that the technologist demonstrated the PICC line from its entry in the left arm (yellow arrow) to the tip (red arrow). Difficulty advancing the catheter is a reason to include the arm and a portion of the neck. The main issue with this radiograph is the poor exposure technique. Notice that we cannot see the thoracic vertebral bodies through the heart silhouette. As a result the lung parenchyma is poorly visualized and the tip of the catheter is barely seen. The location of the catheter, especially the tip can be determined from this radiograph. Anytime the chest is imaged for catheter placement or chest tube it is important that the lungs are evaluated. Repeating this radiograph given the clinical history to evaluate PICC placement would be a breach in ALARA. However, for future reference increase kVp and collimate to the area within the dotted lines in keeping with ALARA. This radiograph does not meet all components of the diagnostic standard, but is diagnostic for the clinical history given.

Radiograph #12

What is your assessment of this supine portable AP chest radiograph? Patient history was simply evaluate lungs, shortness of breath.


The patient is not well centered to the cassette causing the left lung base to be partially clipped. Notice that the right sternoclavicular joint is projected away from the spine and the right SC joint is over the spine. This is a grossly rotated chest radiograph. The patient should be rotated towards the left until the shoulders are flush against the cassette. Alternately, a radiolucent sponge placed under the right chest to rotate the shoulders equidistant distant from the cassette is acceptable. Adjusting patient position will allow for visualization of the medial right lung field. Exposure does not need to be adjusted for this radiograph when it is repeated.

Radiograph #13

A portable radiograph was taken on this patient with known pleural effusion(s) now suffering decreased oxygen saturation readings. Why is this radiograph not acceptable for a portable AP view of the chest?


The main reason this radiograph is not acceptable is that it was performed supine rather than upright. Notice the position marker in the upper left corner (yellow broken circle). When a patient history of pleural effusion is given every effort should be made to position the patient upright. There is obvious fluid in the left lung (yellow arrow); however, it cannot be accurately quantified to previous radiographs unless the patient is upright. Newly developing pleural effusion in the right lung cannot be fully assessed since a portion of the right costophrenic angle is clipped. Suggest repeating this radiograph with the patient properly centered on the cassette not to clip required anatomy, and upright. The exposure technique appears adequate for this patient.

Radiograph #14

Patient had increasing shortness of breath, the ordering physician wanted to evaluate the lungs for fluid. Does this radiograph meet the diagnostic criteria based on the history for the exam?


This radiograph was taken with the patient supine, which is not recommended when evaluating the chest for fluid. An accurate assessment of fluid quantity does require the patient is positioned upright in a manner that can be duplicated for serial radiographs. Notwithstanding, the exposure technique demonstrates poorly penetrated lung fields. There may be patchy infiltrates (yellow arrowheads) developing, which are difficult to see because the chest is under penetrated. There is gross rotation of the chest with the left sternoclavicular joint projected away from the spine. When this radiograph is repeated, roll the patient towards the right until the shoulders are at equal distance from the cassette. Even with a good exposure that penetrates the chest the lung parenchyma would be poorly demonstrated. To optimize this radiograph one must use a grid. Although tube-part-grid alignment is difficult to achieve, it is necessary in order to get it good results on this patient. Use of a grid, increase the kVp, and performing the study with the patient upright are the best way to achieve a highly diagnostic radiograph for this patient. Also, center the patient so that the right costophrenic angle is not clipped.

Radiograph #15

The patient history for this radiograph stated chest tube is not working properly, evaluate placement. Based on this history, does this radiograph meet the diagnostic criteria, and state what could have been done to make it a better radiograph?


Convenience is not a reason to perform a radiograph in the supine position. Based on the clinical history this radiograph should be performed in the upright position. Often patient instability is the factor that determines whether or not a patient should be positioned upright or supine. The supine position should be used only when the physician indicates it or the nurse caring for the patient recommends it due to the patients condition. Examples of scenarios in which the supine position is indicated include among others unstable low blood pressure, trauma spine precaution, post cardiopulmonary resuscitation, and the like. About the radiograph, the upper chest catheter opening is positioned high, which is great for suctioning air, for example, a pneumothorax. In this case the chest tube has a second opening which should be draining fluid from the chest, which is not appreciated on this radiograph. On the right, the lower left lung field is darkened and magnified to show the lower chest tube opening. This is what the physician wanted to see along with fluid level to determine the catheter is properly positioned in the fluid of the chest. Performing this radiograph with the patient upright is necessary to quantify fluid level. Increase the kVp and position the patient upright when this radiograph is repeated, and include both costophrenic angles.

Radiograph #16

This radiograph was taken on a patient who is receiving ventilated breathing support. The technologist thought it would be easier to perform this radiograph supine since the history for exam is to evaluate endotracheal tube placement. What is your critique of this portable radiograph?


Although the patient is not aligned to the cassette the reason this is not an optimal radiograph is that the chest is rotated. The left sternoclavicular joint is widely displaced away from the spine. This distorts the radiograph coupled to the poor alignment of the patient to the cassette. Most radiologists would not require this radiograph to be repeated since it is for tube placement, but unmistakably this is not an optimal radiograph. For future reference, align the patient and reduce rotation of the chest by making sure the shoulders are equal distance from the cassette. Although the exposure demonstrates the vertebral bodies through the heart silhouette, this is not the recommended low contrast exposure. Though difficult to see the endotracheal tube tip is noted to be in the right main bronchus (yellow arrow). A magnified portion of the chest is shown on the right to help you to see it better. The problem with this radiograph is it is under penetrated and is badly rotated. Since the endotracheal tube is in the right bronchus this radiograph should not be repeated until after the endotracheal tube is adjusted. The kVp should be increased approximately 15% to better penetrate the lung and produce low contrast. The reason this radiograph was taken supine is that the patient was sedated and on a ventilator. This is acceptable considering the reason for the study was to check the placement of the endotracheal tube.

Radiograph #17

This radiograph was requested on a patient who was sent to the radiology department on a gurney because of depression. A chest x-ray was requested because the patient complained of chest pain and had a normal electrocardiogram (EKG). Does this radiograph meet the diagnostic criteria for a chest x-ray considering clinical history?


This radiograph shows good positioning of the patient with both sternoclavicular joints symmetrical and lateral to the spine. The apices of the lungs are about 1 inch above the clavicles and the heart and trachea are anatomically projected. The exposure does not demonstrate the vertebral bodies through the heart, but is adequate for this patient. Unfortunately, this radiograph was performed with the patient supine rather than upright. No spine collar is seen, nor any indication that the patients condition warranted being supine. Otherwise, this is an optimal supine radiograph for the patients presentation.

Radiograph #18

This patient presented to the radiology department for a routine chest x-ray. The technologist performed the study upright as the patient was able to stand. What condition caused the chin to be in the upper lung field and how should the technologist approach repeating this radiograph?


his patient obviously had difficulty with the upright position due to a condition called chronic kyphosis. This type of body presentation will often have the chin down, stiffness, and weakness of the neck muscles. It is difficult for the patient to extend the neck out of the upper chest field. Therefore the study should be performed upright with the x-ray beam directed AP rather than PA. It may be necessary to tape the head up and out of the field of view. Notice that the clavicles are projected down into the lung field below the fifth rib. Angling the tube cephalic in this case could prove useful. So repeat this radiograph with the head out of the field of view, correct chest rotation, and possible use cephalic angulation to clear the lung fields. The exposure technique is adequate for this view. The inspiratory effort by the patient is satisfactory but not optimal.

Radiograph #19

What is your critique of this portable chest radiograph performed on an obese patient whose chief complaint was shortness of breath?


This radiograph is an example of the technologist properly aligning the patient to the upright Bucky with the central ray entering at about T6, yet the finished product is unsatisfactory. The patient is upright, the chest shows minimal rotation, and the required anatomy is demonstrated on the radiograph. Because the patient is obese and have large amount of breast tissue, the costophrenic angles are poorly penetrated. Increasing the kVp alone will not compensate sufficiently to make this an optimal radiograph. The patient will have to move the breast up and outward away from the chest. The technologist should increase the mAs by adjusting the automated exposure control to +1 or better +2 gain a 25 to 50% increase. The goal is to achieve an exposure that demonstrates the medial lung bases and costophrenic angles. So repeat this radiograph having the patient move the breast and increase the mAs at least 25 to 50%. Otherwise this is a well-positioned radiograph that includes all required anatomy.

Radiograph #20

This radiograph obviously does not meet diagnostic standards. What should be done to make this an acceptable radiograph?


A patient with extreme chronic kyphosis can be challenging, but this is one example of where patience and technical skill is most required. The oxygen tubing obstructs the field and the patient is grossly rotated. Poor centering, metal snap from the gown, and obvious lack of collimation are all reasons this radiograph should be repeated. To correct this radiograph the patient should be aligned with the cassette, and extend and tape the head back out of the field of view. The posterior ribs have an extreme downward projection as well as the clavicles. The tube will have to be angled cephalic so that no more than 1 inch of the apices are projected above the clavicles. Corrections for this poor radiograph include: placing the shoulders flush with the cassette and equal distance, tape the head back in extension, align patient with the cassette, use collimation, remove surface foreign bodies, and angle the CR cephalic. In some cases where the frontal view does not demonstrate the entire chest a lateral radiograph may be recommended by the radiologist.

Radiograph #21

This patient was brought to a local emergency room following a motor vehicle accident. There were decreased breath sounds bilaterally and the patient was intubated at the scene. After seeing this portable radiograph taken in the emergency room, what could have been done to make this a better radiograph?


When you discover a pneumothorax of this proportion make sure the emergency room physician or radiologist looks at the radiograph immediately. The right lung is deflated (yellow arrows) and a significant amount of air is seen in the pleural space. There is no free air in the subcutaneous tissues. A tension pneumothorax is a life-threatening condition caused by air in the pleural space. It causes compression of the lung, heart, and other mediastinal structures, which appear shifted from the midline. This radiograph will obviously be repeated; however, it may be requested after a chest tube is placed to reduce chest tension from the pneumothorax. As for film quality, we see both left lung is partially clipped and the chest is grossly rotated to the left. The trachea should be in the midline to evaluate expansion of the pneumothorax. Also, there appears to be fluid in the left lung, which should be evaluated apart from the heart shadow cast over it. The exposure technique is good, but there appears to be slight under penetration of the left lateral lung field.

Radiograph #22

This radiograph is a follow up portable chest x-ray to evaluate fluid levels in the lungs and a healing pneumothorax. Does this radiograph meet diagnostic standards for the portable AP chest radiograph?


There is mild rotation of the chest; however the trachea lies anatomically in the midline. There is slight rotation to the right, which is acceptable since serial radiograph may be performed over several days. Whatt makes this radiograph unacceptable is the poor penetration of the lungs as the thoracic vertebral bodies cannot be seen through the heart silhouette. The patient is not centered to the cassette and there are multiple metallic wires within the field that can be moved. This radiograph must be repeated making appropriate changes to include patient centering, positioning in a true upright, shoulders flush with the cassette to reduce rotation, and increase in kVp to better penetrate the lungs. Remove as many of the heart monitor leads as possible so that collimation is possible.

Radiograph #23

Give your critique of this PA upright chest radiograph taken on a young woman of childbearing age?


There are several good points to this radiograph including that the sternoclavicular joints appear symmetrical, shoulders are depressed with the scapulae slightly superimposing the lateral lung margins. All required anatomy is demonstrated on this upright PA chest radiograph. The patients inspiratory effort is good as is the exposure technique. The patients hands are clearly not on the hips with the shoulders depressed and elbows rolled toward the image receptor. As a result there is unnecessary exposure to the arms. On women of childbearing age a lead shield (right photograph) should always be used (represented by the blue shape) to shield the abdomen. Of course close collimation, which is just as important as shielding, should always be applied. The yellow box on radiograph represents the area of collimation that should appear on the radiograph. What should be included are the apices, lateral lungs, and costophrenic angles. Repeating this radiograph for these positioning and collimation errors is not in keeping with ALARA.

Radiograph #24

What is your critique of this supine chest radiograph taken on a patient whose chief complaint was difficulty breathing and abdominal pain with distension?


There are several aspects of this radiograph that do not meet diagnostic standards including being supine rather than upright, clipped apices, and poor inspiration. Supine imaging is reserved for those patients whose condition could be adversely affected if raised to the upright position. Candidates include those on spine precautions, significant trauma, recently resuscitated, hypotensive, some post operative conditions, and so forth. Given a clinical history of distended abdomen (possible bowel obstruction), or worse case scenario a perforated bowel, the upright projection should be made. Part of the evaluation is to look for air-fluid levels in the visualized abdomen, and for air that is not in the bowel (called free air), which may settle beneath the diaphragm when the patient is upright. Being upright would also allow the patient to take a deeper inspiration to expand the lungs. The inferior limit of the right hemidiaphragm (yellow arrow) is seen, but the left hemidiaphragm cannot be determined. This may be due to motion artifact. Perhaps this radiograph should be taken with the cassette turned lengthwise and vertical collimation applied. Repeat radiograph correcting the mentioned errors with the patient upright.

Radiograph #25

What is your critique of this PA upright CXR using the diagnostic criteria for this view?


What is obviously wrong with this radiograph is that both costophrenic angles are not included. A subtle finding is the position of the clavicles. When positioning for the PA chest projection the shoulders are depressed and the midcoronal plane is parallel to the image receptor. This will project the clavicles horizontal (red dotted line) rather than vertical as is seen on this radiograph. Also, proper positioning will demonstrate only about 1 inch of the apices above the clavicles. Always check to see if a patient will fit on a 14 X 17 lengthwise when you have doubt. To do this place your hands at the level of the costophrenic angles and have them inhale deeply while observing to see if your hands are pushed out of the field of view. Repeat this radiograph using a 14 x 17 inch cassette crosswise, have the patient depress their shoulders and align the midcoronal plane with the image receptor. Exposure technique is adequate for this patient.

Radiograph #26

Give your critique of this radiograph taken on a young patient who presented to the emergency room with chest pain and shortness of breath?


This is a radiograph that should have never been taken supine. One reason to perform this radiograph upright is that it allows for the shoulders to be depressed. By doing so at least 1 inch of the apices are projected above the clavicles. Did you notice the small pneumothorax in the left upper lung lobe? When the shoulders are depressed and brought forward this area is better seen. Overall, this is a good radiograph of the chest. There is sufficient inspiration and the patient displays minimal rotation. The exposure technique is adequate for lung tissue and vascular markings.

Radiograph #27

This radiograph was requested on a premature newborn who suffers acute respiratory distress. The purpose for this exam is to check endotracheal tube placement and lungs. Give your critique for this AP portable supine radiograph.


At first glance this radiograph may appear to be acceptable; however it is not. The main reason this radiograph should be repeated is motion artifact and quantum mottling. Notice that the vascular lung marking are ill defined and the bronchi are not aerated. This is because the exposure was taken either on expiration or patient motion has occurred. Generally, pediatric radiographers know to watch the inspiration indicator on the ventilator rather than the patient so that exposure is made on full inspiration. Because ventilators are different you should ask the respiratory therapist to show you what setting to watch for peak inspiration. When an infant is not on a ventilator the abdomen rises with inspiration and falls with expiration. The other issue is that the head is not straight in anatomic position. This can misrepresent of the location of the tip of the endotracheal tube. Collimation of the part is lacking in all directions. While this critique does not normally reference the absence of a position marker it should be noted that this is a serious breach when imaging infants. Congenital variations such as dextrocardia, situs inversus, and others such as transposition syndromes are diagnosed because of the position markers. The effort to reduce patient exposure by using excessively high kVp and low mAs resulted in a photon starved radiograph that lacks subject detail. Quantum mottle combined with motion artifact makes this a very unacceptable radiograph. Overall, this radiograph should be repeated correcting the points mentioned.

Radiograph #28

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