What should be the minimum thickness of filtration for X-ray tubes operating above 70kVp?

The minimum thickness of filtration for X-ray tubes operating above 70 kVp is established at 2.5 mm of aluminum (Al). This requirement is significant for ensuring patient safety and minimizing radiation exposure.

Filtration is the process of using materials, like aluminum, to absorb low-energy X-rays that do not contribute to the diagnostic value of an X-ray image. These low-energy photons can be harmful to the patient due to increased radiation dose without yielding any clinical benefit. By employing a minimum of 2.5 mm of aluminum filtration, the machine effectively reduces the patient's exposure to unnecessary radiation while allowing the higher-energy, diagnostic X-rays to pass through.

The 2.5 mm Al standard is grounded in regulations and guidelines set by health organizations, ensuring that X-ray imaging remains both effective and safe. This thickness has been determined to provide an optimal balance between patient safety and the requisite image quality for medical diagnostics.

In contrast, other options imply lower levels of filtration, which would not adequately shield patients from unnecessary radiation, potentially leading to higher exposure levels.