medical contrast agent

So friends, our topic today is Radio Graphic Contrast Media. Before proceeding on the contrast media, once we know about the contrast, what is the contrast.

So friends, we measure the blackness and whiteness of the various parts appearing on the X-ray film in optical density. The optical density of this white part appearing on X-ray film is low, and the optical density of the black part is high, because they reach more X-ray photons which make the X-ray film black.

The difference in this optical density of the different parts on the X-ray film is called contrast, this contrast differentiates the image of two different body parts located on the X-ray film.

But many times our body is not able to produce any contrast in this X-ray beam, which is called subject contrast, because the difference in the density of the two body organs located in the body is either very low or not at all, which leads to it. X-ray beams are the same, there is no contrast in it, as the arteries and veins of our body do not show in X-rays.

These arteries and veins are visible in the x-ray so that they fill a high atomic number of substances, so that they absorb some of the x-rays in the x-ray beam crossing it, reducing the number of x-ray photons in that part on the x-ray film Due to this, the area produced in the body part will look different from that area. Thus in any body part where there is no contrast, contrast can be generated by placing certain chemicals, and such chemicals are called contrast media.

Therefore, contrast media are those substances of more or less atomic number that change the density of an organ during X-ray examination, and the contrast media is placed in the body part when the subject contrast in that part of the body is less, The use of this contrast media increases the subject contrast in the body.

The second type of contrast media is-

First Negative Contrast Media

Second Positive Contrast Media

Negative contrast media are substances with a low atomic number that reduce their density when placed in a body part, making them transparent or radiolucent to the body part X-ray, which allows the X-ray to easily distinguish that body part, And the optical density of that body part increases on X-ray film.

Positive contrast media are substances with a high atomic number that, when placed in a body part, that body part becomes more radio-opaque, preventing unfathomable X-rays. Barium and iodine compounds are commonly used positive contrast agents.

Barium is commonly used as a contrast agent, barium sulfate, also known as barium meal, is dissolved in water and fed to the patient, and a gastrointestinal study is performed. Barium sulfate in the form of barium meal is used because -

It has a high atomic number of 56, due to which it has a higher absorption of x-rays due to its greater photoelectric effect.

These are non toxic substances.

It is an inert substance that does not react to any other chemical in the body.

It is cheaper than other contrast media.

Iodine compounds are also used as positive contrast media. 90 percent of contrast agents employed in X-ray imaging are intravascular contrast, also known as general contrast media.

Iodine is a radiopaque due to its high atomic weight 126. Due to the high atomic number, it has more photoelectric effect. Because of which it is used as contrast media.