Which PET detector is classified as intrinsically radioactive?

The choice of LSO as the correct answer is based on its intrinsic properties as a detector material in Positron Emission Tomography (PET). LSO, or Lutetium Oxyorthosilicate, is a scintillation crystal that exhibits intrinsic radioactivity due to the isotopes of Lutetium it contains. This intrinsic radioactivity allows it to emit gamma rays when excited by incoming radiation, making it a suitable material for detecting positrons emitted from a radiopharmaceutical during a PET scan.

LSO serves not only as a scintillator but also improves the sensitivity and resolution of PET imaging due to its favorable light output and the fast response time, which are critical for imaging dynamic processes within the body. The fact that it is intrinsically radioactive enables it to contribute to the detection mechanisms within the PET scanner.

In contrast, other detectors listed do not exhibit this intrinsic radioactivity characteristic; Geiger-Muller counters are primarily used for radiation detection in safety monitoring and not specifically for PET imaging. CZT (Cadmium Zinc Telluride) is another type of semiconductor detector that operates on different principles and is also not considered intrinsically radioactive in the context of PET imaging. PMT, or Photomultiplier Tube, is an elect