# What is X-ray? Explained

In the late 18th century and the beginning of the 19th century, a special type of ray was found that has profoundly influenced various branches of science today. Yes, I'm talking about the unknown ray of that time, which is now known as X-rayWhatever the field, it may be the medical field, engineering, science exploration, etc, x-rays are now widely used.

1. What is X-ray?
2. Discovery of X-ray
3. Types of X-ray spectrum
a) Continuous X-ray spectrum
b) Characteristics X-ray spectrum
4. How X-ray is Created?
5. Different uses of X-rays
6. Dangers of X-ray

# What is X-ray?

X-ray is a type of electromagnetic radiation. This type of radiation is capable of penetrating materials (including biological tissue) and ionizing gases. It is similar to light but with extremely short wavelengths and high frequency. The range of wavelengths of an x-ray is about 10^−8 to 10^−12 meters and corresponding frequencies from about 10^16 to 10^20 hertz (Hz).

X-ray imaging can create pictures of the inside of your body. This type of image shows the parts of your body in different shades of black and white. When the x-ray pass-through your body different tissues in your body absorb different amounts of radiation.

This is why the shadow of the image looks black and white. For example - calcium in bones absorbs x-rays most, so bones look white. Fat and other soft tissues absorb fewer x-rays, so they look gray. Air absorbs the least x-ray, so lungs look black.

## Discovery of X-ray

In the year 1995, on November 8, a German physics professor named Wilhelm Rontgen discovered the x-ray. In his paper, he wrote about a new kind of radiation and he referred to the radiation as "X", to indicate that it was an unknown type of radiation. For this discovery, he received numerous accolades for his work, including the first Nobel Prize in physics in 1901.

There are many contradictions to his invention because Rontgen's lab notes burned down after his death. But there is also a reconstruction by his biographers from which his discovery is made known.

When Rontgen was researching cathode rays from a Crookes tube which he had wrapped in black cardboard so that the visible light from the tube could not interfere, using a fluorescent screen painted with barium platinocyanide.

He noticed a faint green glow about 1 meter away from the screen. Then he realized some invisible rays coming from the tube were penetrate through the cardboard to make the screen glow. And he found that they also penetrate through books and papers on his desk.

He threw himself into investigating these unknown rays systematically and after two months after his initial discovery, he published his paper.

Rontgen discovered the medical use of these rays when he made a picture of his wife's hand on a photographic plate formed due to x-rays. This photograph was the first photograph of a human body part using x-rays.

### Types of X-ray spectrums

If you talk about the x-ray spectrum then there are two types of x-ray spectrum named Continuous x-ray spectrum, and Characteristics x-ray spectrum.

Continuous x-ray spectrum

Let, an electron with kinetic energy K hits a target made of molybdenum atom. As the electron moves toward the nucleus, its velocity decreases, which means that the kinetic energy decreases for the collision with another electron.

Suppose such an interaction takes place the electron loses ΔK amount of energy. Now an x-ray photon emits from the collision with the amount of energy the electron has lost.

After the first collision, the electron is likely to have a similar collision with an atom. In this case, the electron collides with the (K-ΔK) energy.

The energy of the x-rays emitted as a result of this second collision is usually lower than the previous x-ray photon. The electron thus collides with various atoms until it reaches a steady state.

As a result of the collision, photons of different energy are emitted. These photons produce a spectrum called the continuous x-ray spectrum. But in reality, not an electron, numerous electrons or currents of electrons hit the target object.

Characteristics x-ray spectrum

If the target is hit with high energetic cathode rays in the x-ray tube. Because the cathode ray electrons are very high energy, they affect not only the electrons outside the atom but also the electrons in the K, L, ... orbits near the atom.

If an electron comes out of this orbit, an electron deficiency occurs in that orbit, also known as a hole. If this hole is created in the nearest orbit of the nucleus (like K), an electron comes from the higher energy orbit (like L, M) to fill this gap.

Electrons emit energy in the form of photon particles while jumping from higher to lower energy levels. These photons particles produce a spectrum called the characteristics x-ray spectrum.

If electron jumps from L to K orbits then the K𝛼 peak of the characteristic x-ray is formed. And If electron jumps from M to K orbits then the K𝛽 peak of the characteristic x-ray is formed.

### How X-ray is Created?

X-rays are produced in standard ways for diagnostic procedures or for research purposes. From cathode filament, electrons are accelerated with a higher voltage and allowed to collide with metal targets. The targets may be tungsten(W) or molybdenum(Mo).

X-rays are produced when the kinetic energy of the electrons suddenly decreased with the collisions of the metal targets. When the kinetic energy of electrons suddenly decreased some x-ray radiations are produced. These x-ray radiations are called bremsstrahlung or braking radiation.

Now if the bombarding electrons have sufficient energy, they can knock out an electron from the inner shell of the target metal atoms. Then the electrons of the higher states go down to fill the void.

Electrons emit energy in the form of photon particles while jumping from higher to lower energy levels. In this way, the x-rays they radiate are called characteristics x-rays.

### Different uses of X-rays

Use of x-ray in the medical field:

The various types of X-rays that are used in the medical field are Abdominal x-ray, Barium x-ray, Bone x-ray, Chest x-ray, Dental x-ray, Extremity x-ray, Hand x-ray, Joint x-ray, Lumbosacral spine x-ray, Neck x-ray, Pelvis x-ray, Sinus x-ray, Skull x-ray, Thoracic spine x-ray, Upper GI and small bowel series, x-ray of the skeleton, etc.

1. Radiography: Radiography is done to monitor body rate and kidney stones.

3. Fluoroscopy: Fluoroscopy is done to take a moving picture of the patient's body.

Use of x-ray in other fields:

In other fields, the role of x-rays are

1. In the laboratory, x-rays are used to analyze the composition of various crystals.

2. X-ray is used to determine the defects of metallurgical welding.

### Dangers of X-ray

When x-rays pass through the body they cause electrons to be ejected from atoms, leaving behind positive ions. These positive ions can cause damage to DNA. If DNA is damaged, there are three possibilities occurs:

1. The cell dies.
2. The cell repairs itself perfectly.
3. The cell repairs itself with mistakes.

This inaccurate repair of DNA can cause a cell to grow into cancer. This only occurs with very high doses of x-rays. So always physicians are aware of the risks and benefits of x-rays, CT scans, and other scans, and always try to balance the potential benefits of patients being tested with small risks.