What is X-rays ?How X-rays are produced?

You must have seen X-ray images, once in your life, like a black film with structure of our Internal organ i.e bones, Heart, Lungs..etc. If not your then, of any relative or your grandparents. So i am going to explain this Xray image in this article and how it is formed.

This is a medical blog, so here i am not going to explain physics behind X rays. In this article you will find, science behind X rays in Medicine. Like How X-ray machine works , what does it do to our body and what are the types of X-ray machines we use.

First i am going to explain a little bit about Radiation,

So ,Radiation are emission or transmission of energy in the form of waves or particles through space. They are basically are two types

We will mainly discuss about EMR or X-rays because its our main topic, but there are some word you should know before going further

1.Ionizing power- It is the ability of radiation to ionize atoms or molecules by removing electrons from them, thus creating positively charged ions or we can say free radicles.Which damages our DNA, thus body.So it's also called damaging power.

ALPHA particles> BETA particles> X-Rays> Gamma Rays.

2.Penetration Power- It's the ability of the radiation to penetrate our body without being absorbed or scattered.Its an important characteristic, because it means the ray will not stay in our body, it get passed through it.Thus, less chance of damage.

Gamma Rays> Xrays>BETA rays>ALPHA Rays

Lets start with the introduction of Xrays Imaging or Radiography: 

 What is X-rays?

These are electromagnetic radiation with wavelengths shorter than those of visible light. So they have high frequency and high energy. As a result it also has high penetration power.

X rays and Gamma Rays have no charge, so they don't show any deflection in electric field.

X ray was discovered by German physicist Wilhelm Conrad Röntgen, who named them "X-rays" because their nature was then unknown ("X" representing the unknown).He first used this rays on his wife, Anna Bertha Ludwig.

X rays are really of Extranuclear production,  means it is released ,outside of nucleus.

So How it is produced?

When a ray of fast moving electron beam get stopped by any thing, it converts its kinetic energy to other form of energy.  Because energy can neither be created or destroyed, it can only  be transformed from one form to another. This energy get converted to 99% heat and 1% X-Rays photons. This 1% is all we need.

So in short, sudden deacceleration of fast moving electron beam, generates X-rays.

Now how can we use it in X ray imaging or Radiography? 

This is a simple X-Ray tube, 

Here ,

Cathode(Filament)- where electron will be released. It is made up of Tungsten+Thorium.

 Anode- where electron is stopped/deflected. It is also made of Tungsten. There are two types of Anode 

1.  Rotating-Constantly Rotating, so that ray will not target only one place.
2. Stationary- Here rays hit only one place of anode,so chances of damage is increased,does not require heavy machinary.Example- Portable x rays machine, Dental x rays machine

We use Tungsten, because of its high melting point.

Window of the X-Ray tube- From here X-rays is produced.

Whole machine is surrounded by two layer,one with Pyrex Glass to absorbs the heat , and with Lead to prevent scattering of X-rays .(Except-Window)

 And it is supplied with high voltage current.

This is a basic structure of X ray machines.

 

Now, when we heat the Filament(cathode),because of high temperature, it releases the electrons (Thermionic emmission).It goes towards anode because of potential, where it is deflected, due to sudden deacceleration, it releases X-ray photons alongside Heat. 

This X-Ray photons are exposed to the patient, because of high penetration power, it passes through the person and the detector which is positioned behind patient, receive the rays, and produce X-Ray report.

Different tissues and structures within the body absorb these X-rays to varying degrees, depending on their density and composition. Dense structures, such as bones and metallic objects, absorb more X-rays and appear white or bright on the resulting image. Soft tissues, such as muscles and organs, absorb fewer X-rays and appear darker on the image.

The detector captures the X-rays that pass through the body and produces an image based on the intensity of X-ray absorption at different points within the body.

This is how X-Rays are formed.

Let's try to elaborate on it a little. We have two types of radiation coming from the X-ray tube due to the process, so what happens is that when an electron (negetively charged) beam is traveling towards the anode, the nucleus, which is positively charged, deflects the electron in a different direction and changes its speed or velocity. Let's say the electron was moving 100 km/h towards the proton, but it was deflected, and its speed was reduced to 40 km/h.

As we all know, energy can neither be created nor destroyed; it can only be transferred to another form, so this energy is transferred in the form of Bremsstrahlung radiation, or braking radiation. It has a polyenergetic and continuous spectrum as it depends on the angle of deflection.

This beam coming from the cathode is also interect with the anode's innermost electron (k-shell), which has the lowest energy and ejects the electron. This creates an empty space, which is filled with outer shell electrons. For example, an inner shell electron with an energy of 40 is replaced by an outer shell electron with an energy of 100. The remaining energy of 60 is emitted.This emitted radiation is known as characteristic radiation.

Fate of X-Rays produced

These X-rays/radiation coming from X-Ray tube shows to two types of effect i.e Photoelectric effect and Crompton effect when it interect with the patient body matter.

Photoeletric effect: 

This is similar to characteristic radiation.The X-ray beam ejects the innermost electron of , which is replaced with the outer electron and then emits radiation.This is mainly responsible for producing contrast in the X-ray film. 

Crompton effect:

The beam also interacts with the outermost shell electron and  ejects it.The remaining energy is converted to scatter radiation. This Crompton effect is bad,as it can blur or fog the X-Ray image.It can also reach the people surrounding it. Lead apron is used to protect the person from this radiation.

Scattered radiation can be reduced by-

 GRID:

 It is placed between the patient and the cassette. It is made upoflead and aluminum. It blocks the scattered radiation, allowing primary radiation.

Collimator:

It is also a Beam limiting device. It narrows the beam onto the patient.It decreases the scattered radiation production.

 

 The contrast of the film can be regulated by 3 factors:

Contrast is the differentiation of black and white in the film.

1.Kvp (Kilovolt peak)

It is the potential, we put on X-Ray tube.Increasing potential can result in increasing electron velocity, thus increasing X-ray energy, means high penetration.

Like in case of Obese patient, we have to increase Kvp, to increase penetration .

2.MAs

It is milliAmpere per second. Increasing it can result in increase in number of electron produced. It is used to increase the contrast of image.

3.Distance

It is the distance between patient and X-Ray tube, increasing Distance results in decreasing intensity. 

Intensity is inversly proportional to square of distance. 

For example, In Child ,we  have to increase distance to lower the intensity.

To increase the contrast of an X-ray film :

Kvp should be decreased and MAs should be increased.

Black and White Principle of X-RAys

•  X-rays passing through less density (air) with maximum  

penetration. The image will be black. 

•  X-rays passing through more density (water or bones) with  minimum penetration. The image will be white. 
•  Maximum attenuation of X-rays is caused by bones. 
•  Increased penetration produces black.
•  Decreased penetration produces white.

e.g OnX-ray

○ Pneumothorax (air)- Black 

○ Pleuraleffusion (water)-Grey/White 

○ Calcification (bones)- White

 Here are some image of X-rays of healthy individuals:

Before finishing this topic i would like to tell about two other ways X-Rays are used i.e Fluroscopy and Mammography.

Fluoroscopy

 Fluoroscopy is a kind of medical imaging in which an X-ray picture is continuously shown on a monitor, like to an X-ray film. It is employed to monitor bodily movements in real time, including blood flow, digestive system movement, and bone and joint location.
 Fluoroscopy produces real-time pictures of inside structures by using X-rays. The picture is produced by the variable amounts of radiation absorption by various tissues as the X-rays travel through the body.
Served as a roadmap for a number of diagnostic procedures, including angiographies, cardiac catheterizations, and barium swallows.
Interventional procedures are frequently utilized to guide joint injections, catheter implantations, and other minimally invasive surgical procedures.

The patient is positioned between an X-ray source and a fluorescent screen during a fluoroscopy. The photos appear in real time on a monitor, and the X-rays are constantly released.
Fluoroscopy can have a larger radiation dosage than a single X-ray picture since it requires continuous X-ray exposure. In order to reduce exposure, protective precautions are used.

 Mammography

Mammography is a specific form of imaging where the human breast is examined using low-dose X-rays. Its main application is in the early diagnosis and identification of breast cancer.
A specialized X-ray system created especially for imaging breast tissue is used by mammography devices. Mammograms are the term for the pictures which is generated.

The breast is compressed between two plates during a mammography in order to spread out the breast tissue. This lowers the radiation required to get an image and provides a more precise view of the breast tissue.

Here is the basic explanation of an X-ray and its uses in medicine.

In this article, i have tried to explain basic concept of X-Rays, types and how it is produced.So please read it, and if you like it then , do read my other blogs. 

If you have any doubt or suggestion, please reach  me at my Contact us page.

Thank you