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Radiography plays an important role in the diagnosis, treatment planning and prognosis of dental diseases. Perhaps, there is no speciality of dentistry that can do without the use of x-radiation. In day to day practice every dentist handles a dental x-ray machine. The construction and operation of an x-ray machine is taught at great length in the dental curriculum. Most of the teaching is based on schematic diagrams of the machine found in radiology text books.

But, one never gets to see the inside of an x-ray machine. Not even the pictures of it! So we decided to open up a defunct dental x-ray machine to take a good look inside. What we found inside mostly corresponded with what is described in the text books. But, there were some differences between the theory and reality.

Following is a picture story of our journey to get the inside of
a dental x-ray tube head outside:

The X-ray Tube Head





The anode end of the x-ray tube is seen through the port, when the plastic seal, too was removed.


The port of the tube head exposed on removing the collimator revealing the aluminium added filtration.

The aluminium filter removed to show the plastic seal that prevents oil leakage and allows space for expansion of oil when it gets heated during operation.


Since the x-ray tube could not be accessed from the port,
the tube head was opened from it's other end.

The tube head, as expected was filled with oil. A rubberized pouch, with an opening on the undersurface was found placed over a plastic container that housed the transformer coils and other circuitry. The pouch provides the extra space required when the oil expands due to the heat generated during generation of x-rays. Generation of x-rays, remember, is not a very efficient process. Only about 1% of the energy of the electrons incident on the tungsten focal spot gets converted into x-radiation. The remaining into heat!

Have we got you interested for the rest of the journey? Then click to continue.