What intrinsic property do LSO and LYSO crystals demonstrate?

The correct answer highlights that LSO (lutetium oxyorthosilicate) and LYSO (lutetium yttrium oxyorthosilicate) crystals exhibit intrinsic radioactivity due to the presence of the element lutetium in their composition. This property stems from lutetium's characteristics as a heavy element that can have naturally occurring radioactive isotopes.

In the context of PET imaging, the intrinsic decay processes contribute to the production of scintillation light within these crystals when they interact with incoming gamma photons. This scintillation light is crucial for the detection of positron emissions and subsequent imaging, making the intrinsic properties of these crystals vital for the performance of PET systems.

While high thermal conductivity, non-radioactive stability, and isolation from electromagnetic interference are beneficial properties for various materials, they are not intrinsic to LSO and LYSO crystals specifically. Their utility in PET is primarily linked to their scintillation properties and the radioactivity associated with lutetium, thereby making the correct answer relevant to their performance in medical imaging applications.