Sunday, July 26, 2020

X ray Machine Working Principle

Hi friends!!!

In our previous blogs we have discussed about Capnography and Interpretation of Capnography Waveform. Please check out for the link given below.


Interpretation of Capnography Waveform

In today’s blog, we are going to discuss about the x ray machine working principle.

X ray is a radiography equipment which has created a revolution in the field of diagnostic healthcare. It produces the images of inside of our body in black and white. Therefore it is important for every healthcare professional to know in detail about X rays.

Let’s get into the topic.


X Ray was discovered by German physicist Wilhelm Roentgen in 1895. In an eagerness to find out the behaviour of electricity in a vacuum, Roentgen removed the air from the tube which made electrons to move fast. The fast moving electrons hits a anode in the tube and produced a type of light. This is how x ray production took place for the first time. Roentgen noticed that this type of light is not yet discovered and it is called X Ray.

Image courtesy: Wikimedia commons
Licensed under: CC Share Alike 


X rays are almost similar to visible lights. But the only difference is that they have different wavelengths. We can see visible light of higher wavelength, but we cannot see the X ray beams with lower wavelength and high energy. The frequency of X rays is 1020 Hz and wavelength ranges from 10 Picometres to 10 Nanometres.



Let us discuss in detail about the x ray machine working principle. Following is the image of the x ray tube.

Image courtesy: Wikimedia commons
Licensed under: CC Share Alike 

The x ray unit consists of a x ray tube which has hot cathode filament and anode made up of heavy metal placed in a vacuum tube made of glass. The electric current is made to pass through the cathode filament, which in turn heats the cathode filament. The heat activates the electrons from the filaments surface. The positively charged anode draws the activated electrons across the x ray tube from cathode to anode.

Thus the fast moving electrons hits the anode element. Because of the collision of the fast moving electrons, the atoms in the anode loses electrons in the lower orbit. With the lose of electron, the atom becomes unstable. To come back to its normal equilibrium position, the atoms in the anode sends the electrons from higher orbit to fill the vacancy in the lower orbit. As a result X ray beams are produced.

The x ray production takes place from the slanting surface of the anode. Meanwhile along with X ray beam, high amount of heat is also produced. To prevent the anode damage due to excessive heating, a induction motor is used to rotate the anode in order to limit the heating at one particular spot.

A filter is placed near the X ray source which blocks the low energy X rays. So only high energy X rays from the x ray machine passes through the patients to reach the thin sheet of photographic x ray film. X ray beams from the x ray machine pass through the lower density objects such as muscles or flesh whereas in higher density objects like bones, X ray beams are absorbed. The absorbed X ray beams appears as a bright spots on the x ray film. Soft tissue such as skin and organs cannot absorb high energy X ray beams. 

Image courtesy:
Licensed under: CC Share Alike 



Most x ray tube uses tungsten as an anode material.The x ray production depends upon two factors, atomic number of anode material and energy of electrons. Reason to use tungsten is that it has a high atomic number of 74. As discussed earlier, heat is also produced along with X ray beam. In order to eliminate the effect of high heat, the tungsten element shows maximum strength at high temperatures. It has high melting point and also a low rate of evaporation. The shape of the anode is usually beveled shape discs.


Now I hope you have acquired some knowledge about the x ray machine working principle. We will discuss in detail about  x ray tube parts in our next blog.

NOTE: Dear friends!!! ...Please do comment a topic related to Biomedical, so that we can discuss it in future blogs.

Check out for this blog about Computed Tomography

Generations of CT Scanners




If you find this blog post knowledgeable, comment & share it with a friend! 




  1. Nice explanation with pictures

  2. Dear Mr. Kaushik,
    It is a good and enlightening article. Congrats.
    I object your assertions on Mr. Roentgen and entire credits of even the 'then prevailing' wisdom of vaccuum tubes to the German Physicist.
    The very first NOBEL Prize was awarded to him. for this invention.
    You know, like myriads of scientists the actual invention of X-Ray was done and well tried by another unfortunate man his name was Ivan Puluj from Ukrain. He was a year senior to Mr. Roentgen. Puluj did show his findings and explanied the nuances of xRays with Roentgen.
    He started his search as early as 1880 and invented X-Ray very well before Roentgen. He even applied for approval to the Austrian Society of Science earlier. They rejected the thesis saying the language he used was "obscure"!!
    I am initiating a very significant DIG here for you-

    And I would like to express a good wish to your effort. The betrayal of fellow scientists, governments, powerful nations... are well known to every one. You did nothing wrong.
    But reality is so bitter for people like us- the downtrodden.
    Let us pay our tribute to a forgotten Genius in IVAN PULUJ.

    1. Excellent information. You have shared a information which is unknown to many of us. Thank you for your interest in highlighting the truth by commenting. Sure will learn further about your statement and update my contents accordingly. Thank you.

  3. Well i am a doctor and i know the process on working x ray machine. Every points which is mention on this articles is 99% right. good Job