Tail pain and refusal to sit often occurs in tailbone fracture and dislocation, patients often do not like to sit because of tail pain, or even refused to sit, willing to lie on the side of the bed to rest. Tail fractures and dislocations are significantly more common than sacral fractures, especially in women, and are common in life and sports accidents. The examination items of tail pain and refusing to sit are as follows: I. Bone imaging Bone imaging can be 3~6 months earlier than X-ray examination for diagnosis of bone tumor and bone metastatic tumor, but it should be noted that this method is high sensitivity and low specificity. Routine bone imaging refers to static bone imaging of the whole body or local area 2-3 hours after intravenous injection of bone imaging agent. Intravenous injection of the imaging agent, static 2-3 hours, at this time did not enter the bone tissue of the imaging agent most of the excretion from the kidneys, the blood radioactivity as the background has been significantly reduced, the bone image is clear. 2.Because of the uneven distribution of bone imaging agent in the bones of normal people, the method of comparing the radioactivity of the symmetrical parts of the left and right sides is used to identify the lesion site and normal bone tissue. 3.Dynamic bone imaging refers to the three-time-phase bone imaging technology, three-time-phase imaging technology is in the intravenous injection of bone imaging agent at different times for a number of imaging, respectively, the collection of blood flow, blood pools and delayed (static) bone imaging data, Tc-MDP “bullet” type intravenous injection immediately after the speed of 2 seconds a frame of continuous collection of one minute, to obtain the lesion site and its symmetrical parts. Obtain the arterial perfusion series images of the lesion site and its symmetric parts, at this time, the large arteries and secondary arteries can be seen one after another, followed by the gradual display of the soft tissue contour. B. CT examination of bone joint and soft tissue CT examination of bone joint and soft tissue is a method to examine bone joint and soft tissue through CT. It mainly focuses on injuries and diseases of bone joints and soft tissues. It is suitable for patients suffering from bone joint and soft tissue diseases and has diagnostic significance for bone joint and soft tissue diseases. 1.Drugs are injected intravenously, and different imaging agents are used according to the different purposes of the examination. After injection, please rest quietly, do not talk with others and avoid tense position. Waiting time after injection is different for different examination items (basically more than 40 minutes). 2.Empty urine before PET/CT examination (for tumor screening) to avoid urine contamination of body surface and clothes. 3.Body PET/CT examination process requires arms up, the general examination time is about 20 minutes; brain examination does not require arms up, the general examination time is about 10 minutes. Family members are usually not allowed to enter the scanning room during the scanning process. 4. After the examination is completed, the doctor in charge observes whether the image quality meets the requirements and informs the patient to leave after approval; according to the needs of the condition, some patients may need to undergo delayed imaging or CT enhancement scanning, and an informed consent form should be signed before the CT enhancement examination.