A normal CXR (chest X-ray) is also known as Chest Radiograph. Doctors mostly use it to evaluate the thorax.

It is almost the first image scanning. It is used to know the pathogenesis of thorax and diagnosis of heart, lungs, liver, etc.

A chest x-ray is also necessary to diagnose Pneumonia, Heart failure, Emphysema and corona, and many other diseases. However, further diagnostic imaging, lab test, and physical examinations are necessary to confirm the diagnosis.              

There are different ways to perform normal CXR (chest X-rays), which are described below in the description.

What is a Normal Chest X-ray & How It Is Performed?

Normal X-ray of the Chest

A registered doctor observes chest x-ray if there is clear of any air spaces or dots. If it has some dots, bubbles, or dark spots, it is not a normal chest x-ray. It has some infection and needs to be treated accordingly.

Method to perform Normal chest X-ray

Routine chest x-rays or radiographs are performed through a machine. The machine emits x-rays on a patient that needs to be examined. X-rays travel or transverse through the patient’s body and are imprinted on the opposite side of the body. The structures in the chest absorb these X-rays in CXR. Their absorption rate is different depending upon the obstacle provided by the body parts in their way.

The appearance of Normal Chest X-ray

Following are the parts of the x-ray radiograph that appear on a normal chest x-ray.

1. Bones appear white on normal chest x-ray
2. Air appear black on a normal chest x-ray
3. Other body tissues appear in the spectrum between white and black.

Methods/Procedure to Read the Normal Chest X-ray

Following are the methods through which the normal x-ray of the chest is determined.

Determination of View

When the patient on which CXR is to be performed presents, the view is the first thing to determine, i.e., the position of the man and the patient. This is necessary so that the trajectory of x-rays emitted through the x-ray machine prints a proper normal x-ray on radiograph or x-ray film.

We can perform a normal chest x-ray  in any of these ways,

1. Posteroanterior  ( PA )
2. Anteroposterior  (AP )
3. Lateral

Although the standard form to perform a normal chest x-ray is posteroanterior,

These terms are related to the position of the patient. Therefore they tell you that x-ray beams travel between the subject/chest to radiograph.

Posterioanterior films

These are standard films for a normal chest x-ray

The patient sits or stands upright in front of the x-ray beam source in the field of almost 6 feet and the receptor of normal chest x-ray on the other side.

Doctors prefer to perform it when the lungs are full of air, i.e., the patient is asked to inhale, he is in fully inspired condition, and the air he can inhale.

Lateral films/examination

In this type of normal chest x-ray, the patient sits or stands upright. He uplifts his arm and then rotates to 90 angles.

This is necessary to allow the x-rays to travel through the right side of the chest to the left, where the receptor is present to film the x-rays coming from the x-ray machine traveled through the body of the patient.

Anteroposterior films

This is the last condition to perform x-rays, in which the patient lies on the receptor of the x-ray. The x-rays travel through the anterior side of the body to the posterior, which records the radiograph.

This condition is performed in a patient who cannot sit upright or stand due to medical reasons/injuries.

Doctors perform these x-ray films at the bedside of the patient mostly. Sometimes the patient is brought to the x-ray department.

Limitation of AP over PA

Normal chest x-ray films obtained from this procedure of AP films have much more faults than obtained from PA films due to many reasons,

Listed below are the possible reasons:

1. In lying condition on the bed, the patient cannot fully inspire lungs, so normal chest x-rays have a limitation when it is performed anteroposteriorly.
2. The other main limitation of this procedure is the heart and mediastinum, which appear large in AP films.

Determination of Image Quality In Normal chest X-ray

In a normal chest x-ray, there is a lot to consider the best quality of a radiograph.

Some mnemonics conclude the quality of an image, like R.I.P., which is ROTATION, and INSPIRATION& PENETRATION.

The body should be straight (norotation)

There should be no Rotation to access the normal chest x-ray of the patient. If we do not place the patient in the right position in front of the x-ray machine, there will be a disturbance in the radiograph. This is because x-rays passing through the patient’s body have a different area on the right and left side of the mediastinum.

Put your heed on the medial aspect of the clavicle, differentiate the right and left medial clavicle joints to the spinous processes in the more central position of a radiograph.

Two conditions can disturb the normal x-ray of the chest during rotation of the body of the patient,

Given below are the conditions:

1. Suppose we rotate the patient in the right direction. In that case, the distance between the right joint’s medial margins will be greater than the distance between the medial margin of the left sternoclavicular joint and the spinous process.
2. Suppose we rotate the patient in the left direction. In that case, the distance between the left sternoclavicular joint’s medial margin and the spinous process will be greater than the distance between the left sternoclavicular joint’s medial margin and the spinous process.

Inspiration

For a good diagnostic study of a normal chest x-ray, the patient must be fully inspired (their lungs should be full with air inspired by the patient).

We can determine it by counting the ribs on the posterior side of the thorax. If you can count at least ten ribs on the posterior side, then the best radiograph will come from a normal chest x-ray.

Penetration

Penetration refers to the extent to which x-rays pass through the body during a normal chest x-ray of the body to get a clear image of a radiograph.

The x-rays are of good penetrating quality if vertebrae present behind the heart are slightly visible. The diaphragm, which is present on the lower border of the chest, can be traced until reaching the edge of a spine in a radiograph in a normal chest x-ray.

The systemic approach to evaluate chest x-ray

In a normal chest x-ray, once the quality of a radiograph is accessed, you can begin to access the radiograph, the pathology, and all related things to it.

It is very important to know every aspect of a radiograph, for that you need to put consideration on every delicate part of a radiograph. If you don’t do so, you can miss many features of the radiograph, which are likely highly harmful to the patient.

Due to this reason, radiologists always advise performing the systemic approach of a radiograph to reduce the mistakes in normal chest x-rays.

One of the simplest ways to remember the steps of systemic approach is again with a mnemonic, and one of the simplest mnemonic for this is ABCs;

1. Air, airways, apices,
2. Bones
3. Cardiac shadow, cardiovascular system

Air, Airways, Apices

When you look at the normal chest x-ray, which is the first thing you should focus on a radiograph?. If you think it’s lungs, then it’s a good approach. This is because you observe the lungs first in the systemic approach of a normal chest x-ray.

Air appears dark on the radiograph. If the lungs appear dark and without any spots, i.e., white spots, etc, then it is a normal and healthy radiograph of a normal chest x-ray. Lungs don’t look pure black because of other tissues present there, but they are quite dark.

If the patient’s radiograph has some spots like densities, you should observe if the densities are localized or spread on the whole lungs. Then it would be best if you compared the radiograph with the physical findings of the patient and history taken from the patient.

Clinical malignancies observed in chest x-ray (CXR)

If a density is present in one of the lungs of a patient and has definite borders around it, then the patient might be having weight loss, a cough, or the mass lesion in the lungs may represent a malignancy.

1. We will also observe vascular congestion in chest x-ray

If the densities appear to be diffused on radiograph spreading on vessels and visible to borders of the lung, the patient may have vascular congestion due to heart failure.

2. Atelectasis (collapse of lungs)observed in chest x-ray.

Examination of the trachea is necessary in normal chest x-ray; if the trachea is not in midline place, you will notice foreign bodies in bronchi; midline shift of other medical structure, then the patient is suffering from the collapse of lungs (atelectasis) in the chest x-ray.

3. Sarcoidosis ( granulomas ) observed in chest x-ray

Look at the hilar region (the hilar region is the point in the chest where the trachea bifurcates, forming the right and left main bronchi which follow their path to the lungs). If the patient has bilateral hilar lymphadenopathy ( i.e., enlarged lymph nodes on both the left and right ). You should be able to observe this on a chest x-ray. This condition you observe signifies the presence of sarcoidosis.

4. Covid-19 0bserved in chest x-ray

Even though the number of cases observed in chest x-ray is less, they are confirmed in CT scans.

Given below are a characteristic set of findings:

• Ground glass opacity observed in chest x-ray, nodular shadowing observed in chest x-ray and observing it affects mostly lower areas of lungs in radiograph of chest x-ray in covid-19 patients.
• Chest x-ray observed in corona patient is given below, with permission of the patient,