Answer to Question #11198 Submitted to "Ask the Experts"

Category: Medical and Dental Equipment and Shielding — Equipment

The following question was answered by an expert in the appropriate field:

Q

Are there any differences in design and manufacturing of x-ray tubes that are used for medical purposes and for security purposes? Are there any references to read more about their differences (differences can include materials, focal spot, dimensions, and so on)?

A

The production of x rays is still accomplished the same way that Roentgen did it over 100 years ago. Electrons with high velocity (energy) are attracted by a positive metal plate and collide with it. The electrons lose their energy by means of bremsstrahlung and characteristic radiation, creating x rays.

The major differences between x-ray tubes used in industrial or medical applications (or any others) are:

1. The amount (intensity) of radiation that you need per second.
2. The energy that you need to go through the material that you want to examine.

These two items will determine the "size" of your x-ray tube, due to the amount of heat that will be produced and the way that the energy is removed from the anode and tube. This will also determine the thickness of the tube housing due to the amount of shielding that will be needed to absorb scatter and leakage x rays.

Therefore, it is not necessarily the use of an x-ray tube that determines its design, but it is the kind of radiation that you need and the quality of image (due to focal spot size) that you desire. Industrial x-ray tubes can be very small or very large compared to medical x-ray tubes, and one can find the profile of each tube by looking at manufacturers' websites.

Professor Flávio Augusto P. Soares

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
Answer posted on 25 March 2015. The information posted on this web page is intended as general reference information only. Specific facts and circumstances may affect the applicability of concepts, materials, and information described herein. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice. To the best of our knowledge, answers are correct at the time they are posted. Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society.