Which term describes the thickness of a material that will stop x-ray photons?

The term that accurately describes the thickness of a material that will stop x-ray photons is "half-value layer." This term refers to the thickness of a specific material required to reduce the intensity of x-ray radiation to half of its original value. The half-value layer is an important concept in radiology and radiation safety, as it helps in understanding how different materials can attenuate x-rays and the necessary safety protocols for working with radiation.

"Lead equivalent" is often used in the context of shielding and describes a material's effectiveness in absorbing radiation compared to lead. However, it does not specify a particular thickness that would stop x-rays. "Photoelectric absorption" refers to a specific interaction between x-ray photons and matter, where the photon is absorbed completely, leading to electron ejection. This is a process rather than a measure of material thickness. "Milliampere-seconds" is a unit of measurement related to the quantity of x-ray exposure but is not associated with the concept of material thickness to stop x-ray photons.