PET-CT is a new diagnostic technology introduced at the beginning of the 21st century, the reason why it can develop rapidly in just a few decades is mainly because PET-CT examination has the incomparable advantages of ultrasound, CT, MRI and other common examination equipment. PET (functional metabolic imaging) and CT (anatomical structural imaging) are organically combined to complement each other’s advantages. Compared with ordinary CT, MRI and other imaging examinations, PET-CT can detect abnormal lesions earlier and more accurately, and play a 1+1>2 benefit. One time localization can check the whole body One time localization obtains the whole body information, the whole body cross-sectional, sagittal and coronal images, can see the disease in the whole body of the affected parts and the situation, saving a lot of other imaging needs to be checked one by one part of the time and money. High sensitivity to tumor PET-CT can accurately detect the lesion site in the early stage of the tumor where the morphology and structure of the lesion area are not yet abnormal but the cellular molecules have already changed, and obtain three-dimensional images to achieve early diagnosis, which is incomparable with other imaging examinations. Fourth, it has strong specificity for some tumors When MRI and CT examination find tumors in organs, it is very difficult to judge whether they are benign or malignant, especially in the early stage of lesions, while PET-CT examination can make a clear diagnosis according to the characteristics of high metabolism of malignant tumors. Accuracy of more than 92% According to the high metabolic characteristics of malignant tumors, glucose with fluorine label should be injected into human body before PET-CT examination, which makes the lesion area appear abnormal concentration, and then the lesion site can be determined. This method can effectively detect most of the tumors, and the diagnostic rate of early cancer foci can be as high as more than 92%. Sixth, the whole examination process is non-invasive, painless PET-CT examination is a kind of non-invasive imaging examination equipment, there is no pain and trauma, no noise, the examinee only needs to receive intravenous injection of a trace amount of tracer and lying down to rest, without any other discomfort. Low radiation, safe and reliable Although PET-CT has radiation, the amount of nuclides used is very small, and the half-life is very short, the time of retention in the body of the examinee is very short, and the whole examination process is safe and reliable.PET-CT adopts micro-radiation and low-dose mode, and high-quality image development method, which is safe for the human body. Evaluation of the efficacy of tumor recovery After treatment by surgery, radiotherapy, chemotherapy and other methods, whether the tumor changes, whether the activity of cancer cells decreases, and whether there is any proliferation in other parts of the body can be detected by PET-CT images, which is of great significance in guiding the adjustment of the next treatment plan.