The spinning target of a general-purpose x-ray tube is primarily composed of which material?

• A. Aluminum
• B. Lead
• C. Gadolinium
• D. Tungsten

Answer: (D)

Spinning target must withstand very high heat while efficiently producing X-rays, so the material is chosen for both heat tolerance and X-ray efficiency. Tungsten fits these needs well: it has an exceptionally high melting point, so it resists damage under the intense electron beam, and its high atomic number increases the likelihood of X-ray production. The rotating anode helps spread the generated heat over a larger surface area, reducing temperature rise at any one spot and preventing local damage during high-power operation. That combination makes tungsten the primary material for the spinning target.

Aluminum would overheat easily and produce fewer X-rays due to its low atomic number; lead is dense but not ideal for heat conduction and X-ray production properties; gadolinium is not used for this purpose due to cost and unsuitable physical properties.