First of all, the difference between SPECT-CT and PET-CT, PET-CT is positron body imaging, we inject a kind of positronuclide, while SPET-CT injects technetium-99, an isotope, mainly used for whole body skeletal imaging, that is to do SPECT-CT, is the whole body skeletal imaging from head to toe, so it is different from PET-CT, PET-CT is SPECT-CT is also the result of invention in the last few years, it is just called SPECT, ECT for short, or simply called bone scan. Then a fracture or some other lesion will also show high metabolism, and it is more difficult to identify at this time. Therefore, CT is now added to the CT scan, and after the complete body skeleton scan, CT scan is added to the rib cage in the chest, so that we can observe whether it is a fracture or a bone metastasis. Because fractures can be seen as fracture lines on CT, and bone metastases show bone destruction, it significantly improves the accuracy of SPECT in the diagnosis of skeletal disease.