Nuclide bone imaging, a bone detection technique by means of chemisorption with hydroxyapatite crystal surface binding to organic matter. Why is nuclide bone imaging the most advantageous examination in nuclear medicine? 1.Principle: The radioactive drug used for bone imaging is 99mTc-MDP, i.e. methylene diphosphonate, which contains the structure of “P-C-P”. After intravenous injection, it can be adsorbed by the hydroxyapatite in the bone and participate in bone salt metabolism. When the bone is damaged for various reasons, the local bone salt metabolism increases during the repair process. After intravenous injection of 99mTc-MDP, radioactive aggregation foci can be detected locally in the injury. Using this principle, the bones of the injured parts of the whole body can be accurately located and diagnosed. 2.Advantage: The most widely used and valuable examination item of ECT in clinical practice is bone imaging. Bone imaging has advantages that cannot be surpassed by other imaging technologies for the localization and diagnosis of tumor bone metastases and occult bone injuries: first, comprehensiveness: one examination can complete the judgment of all skeletal metabolism of the whole body; second, high sensitivity: bone imaging responds to minor bone injuries and can detect lesions 6 months earlier than X-ray or CT, MRI and other imaging. Bone imaging is mainly due to the diagnosis of tumor bone metastasis, localization of primary bone tumor, localization of occult bone injury, osteomyelitis and early diagnosis of femoral head necrosis, identification of post-arthroplasty complications and diagnosis of metabolic bone disease. Nowadays, the widespread application of SPECT/CT can perfectly combine the respective advantages of ECT and CT, which can not only detect lesions at an early stage, but also accurately localize them and provide precise local structural relationship of lesions, achieving the super value benefit of “1+1>2”, changing the limitations and “ambiguity” of once simple ECT diagnosis. “ambiguity”.