X ray chest pa view why

Thank you for updating your details. Log In. Sign Up. Become a Gold Supporter and see no ads. Log in Sign up. Articles Cases Courses Quiz. About Recent Edits Go ad-free. Edit article. View revision history Report problem with Article. Citation, DOI and article data. Murphy, A. Chest PA view. Because chest x-ray is fast and easy, it is particularly useful in emergency diagnosis and treatment. This exam requires little to no special preparation. Tell your doctor and the technologist if there is a possibility you are pregnant.

Leave jewelry at home and wear loose, comfortable clothing. You may be asked to wear a gown. The chest x-ray is the most commonly performed diagnostic x-ray examination. A chest x-ray produces images of the heart, lungs , airways, blood vessels and the bones of the spine and chest. An x-ray exam helps doctors diagnose and treat medical conditions. It exposes you to a small dose of ionizing radiation to produce pictures of the inside of the body.

X-rays are the oldest and most often used form of medical imaging. Remove jewelry, removable dental appliances, eyeglasses, and any metal objects or clothing that might interfere with the x-ray images. Women should always tell their doctor and technologist if they are pregnant. Doctors will not perform many tests during pregnancy to avoid exposing the fetus to radiation. If an x-ray is necessary, the doctor will take precautions to minimize radiation exposure to the baby.

See the Safety in X-ray, Interventional Radiology and Nuclear Medicine Procedures page for more information about pregnancy and x-rays. The equipment typically used for chest x-rays consists of a wall-mounted, box-like apparatus containing the x-ray film, or a special plate that records the image digitally. An x-ray producing tube is positioned about six feet away. The equipment may also be arranged with the x-ray tube suspended over a table on which the patient lies.

A drawer under the table holds the x-ray film or digital recording plate. Compact, portable x-ray machines can be taken to the patient in a hospital bed or the emergency room.

The x-ray tube is connected to a flexible arm. The technologist extends the arm over the patient and places an x-ray film holder or image recording plate under the patient. X-rays are a form of radiation like light or radio waves. X-rays pass through most objects, including the body. The technologist carefully aims the x-ray beam at the area of interest. The machine produces a small burst of radiation that passes through your body.

The radiation records an image on photographic film or a special detector. Figure 1 Radiographs and line diagrams demonstrating the difference between a PA and AP projections For all projections the patient needs to be positioned parallel to the detector so that the median sagittal plane is at right-angles to, and in the midline of, the image receptor.

For both projections the scapula should be rotated so they do not obscure the lungfields. The lungs, mediastinum and bony thorax ribs, spine and clavicles need to be demonstrated. Some spine detail is visualised through the heart and mediastinum. Symmetry is checked by having the medial ends of the clavicle equidistant from the spinous process.

The X-ray beam is projected onto the detector with the patient in the beam to produce a radiograph. Notice that there is quite some lung volume below the dome of the diaphragm, which will need your attention arrow. Here an example of a large lesion in the right lower lobe, which is difficult to detect on the PA-film, unless when you give special attention to the hidden areas.

Here a pneumonia which was hidden in the right lower lobe mainly below the level of the dome of the diaphragm red arrow. Notice the subtle increased density in the area behind the heart that needs special attention blue arrow. This was a lower lobe pneumonia. We know that in some cases there is an extra joint in the anterior part of the first rib which may simulate a mass.

However this is also a hidden area where it can be difficult to detect a mass. In this case a small lung cancer is seen behind the left first rib. Notice that is is also seen on the lateral view in the retrosternal area. The diagnosis was made by a biopsy of an osteeolytic metastasis in the iliac bone.

There is a subtle consolidation in the left lower lobe in the hidden area behind the heart. Again there is increased density over the lower vertrebral region. On a chest film only the outer contours of the heart are seen.

In many cases we can only tell whether the heart figure is normal or enlarged and it will be difficult to say anything about the different heart compartments. However it can be helpful to know where the different compartments are situated. Left Atrium enlargement This is a patient with longstanding mitral valve disease and mitral valve replacement.

Extreme dilatation of the left atrium has resulted in bulging of the contours blue and black arrows. Right ventricle enlargement First study the PA and lateral chest film and then continue reading. On these chest films the heart is extremely dilated. Notice that it is especially the right ventricle that is dilated. This is well seen on the lateral film yellow arrow. There is a small aortic knob blue arrow , while the pulmonary trunk and the right lower pulmonary artery are dilated. All these findings are probably the result of a left-to-right shunt with subsequent development of pulmonary hypertension.

The location of the cardiac valves is best determined on the lateral radiograph. A line is drawn on the lateral radiograph from the carina to the cardiac apex. The pulmonic and aortic valves generally sit above this line and the tricuspid and mitral valves sit below this line 4.

On the right side of the chest the lung will lie against the anterior chest wall. On the left however the inferior part of the lung may not reach the anterior chest wall, since the heart or pericardial fat or effusion is situated there. This causes a density on the anteroinferior side on the lateral view which can have many forms. It is a normal finding, which can be seen on many chest x-rays and should not be mistaken for pathology in the lingula or middle lobe.

The explanation for the cardiac incisura is seen on this CT-image. At the level of the inferior part of the heart we can appreciate that the lower lobe of the right lung is seen more anteriorly compared to the left lower lobe.

Pacemaker There are different types of cardiac pacemakers. Here we see a pacemaker with one lead in the right atrium and another in the right ventricle. A third lead is seen, which is guided through the coronary sinus towards the left ventricle. This is done in patients with asynchrone ventricular contractions. Pacing both ventricles at the same time will lead to synchrone contractions and a better cardiac output. More on cardiac pacemakers Whenever we encounter a large heart figure, we should always be aware of the possibility of pericardial effusion simulating a large heart.

On the chest x-ray it looks as if this patient has a dilated heart while on the CT it is clear, that it is the pericardial effusion that is responsible for the enlarged heart figure. Especially in patients who had recent cardiac surgery an enlargement of the heart figure can indicate pericardial bleeding. This patient had a change in the heart configuration and pericardial bleeding was suspected.

Ultrasound demonstrated only a minimal pericardial effusion. Continue with the CT. There is a large pericardial effusion, which is located posteriorly to the left ventricle blue arrow. The left ventricle id filled with contrast and is compressed red arrow. At surgery a large hematoma in the posterior part of the pericardium was found.

Notice that on the anterior side there is only a minimal collection of pericardial fluid, which explains why the ultrasound examination underestimated the amount of pericardial fluid. Notice the large heart size. There is redistribution of the pulmonary vessels which indicates heart failure. Detection of calcifications within the heart is quite common.

The most common are coronary artery calcifications and valve calcifications. In this case there are calcifications that look like pericardial calcifications, but these are myocardial calcifications in an infarcted area of the left ventricle.

Necrosis of the fat pad has pathologic features similar to fat necrosis in epiploic appendagitis. It is an uncommon benign condition, that manifests as acute pleuritic chest pain in previously healthy persons Pericardial cysts are connected to the pericardium and usually contain clear fluid.

The majority of pericardial cysts arise in the anterior cardiophrenic angle, more frequently on the rightside, but they can be seen as high as the pericardial recesses at the level of the proximal aorta and pulmonary arteries Most patients are asymptomatic. The vessel margins are smooth and the vessels have branches.

The left pulmonary artery runs over the left main bronchus, while the right pulmonary artery runs in front of the right main bronchus, which is usually lower in position than the left main bronchus. Hence the left hilum is higher than the right.

Only in a minority of cases the right hilus is at the same level as the left, but never higher. In this illustration the lower lobe arteries are coloured blue because they contain oxygen-poor blood.

They have a more vertical orientation, while the pulmonary veins run more horizontally towards the left atrium, which is located below the level of the main pulmonary arteries. Both pulmonary arteries and veins can be identified on a lateral view and should not be mistaken for lymphadenopathy. The left main pulmonary artery passes over the left main bronchus and is higher than the right pulmonary artery which passes in front of the right main bronchus.

These images are thick slab sagittal reconstructions of a chest-ct to get a better view of the hilar structures. The lower lobe pulmonary arteries extend inferiorly from the hilum. They are described as little fingers, because each has the size of a little finger 1.

Study the CXR of a year old male who fell from the stairs and has severe pain on the right flank.. Notice on the PA-film the absence of the little finger on the right and on the lateral view the increased density over the lower vertebral column. Notice the abnormal right border of the heart.

The right interlobar artery is not visible, because it is not surrounded by aerated lung but by the collapsed lower lobe, which is adjacent to the right atrium. On a follow-up chest film the atelectasis has resolved. We assume that the atelectasis was a result of post-traumatic poor ventilation with mucus plugging. Notice the reappearance of the right little finger red arrow and the normal right heart border blue arrow.

In this case there is an enlarged hilar shadow on both sides. This could be the result of enlarged vessels or enlarged lymph nodes. A very helpful finding in this case is the mass on the right of the trachea. This is known as the sign in sarcoidosis, i. Mediastinal masses are discussed in more detail in Mediastinal masses.

The mediastinum can be divided into an anterior, middle and posterior compartment, each with it's own pathology. Mediastinal lines or stripes are interfaces between the soft tissue of mediastinal structures and the lung. Displacement of these lines is helpful in finding mediastinal pathology, as we have discussed above.

The most important mediastinal line to look for is the azygoesophageal line, which borders the azygoesophageal recess. Notice the displacement of the upper part of the azygoesophageal line on the chest x-ray in the area below the carina.

This is the result of massive lymphadenopathy in the subcarinal region station 7. There are also lymphomas in the neck. Here we see a CT-image. The azygoesophageal recess is displaced by lymph nodes that compress the left atrium.

The final diagnosis of small cel lungcancer was made through a biopsy of a lymphnode in the neck. The AP-film shows a right paratracheal mass. The azygoesophageal recess is not identified, because it is displaced and parallels the border of the right atrium.

The large round density in the left lung is the result of aspiration. The aortopulmonary window is the interface below the aorta and above the pulmonary trunk and is concave or straight laterally. Here the AP-window is convex laterally due to a mass that fills the retrosternal space on the lateral view. Lung abnormalities mostly present as areas of increased density, which can be divided into the following patterns:. These lungpatterns will discussed in more detail in an article that will be published soon: Chest X-Ray - Lung disease.