The full name of pet examination is positron emission computed tomography, which can provide tomographic images in all directions, and is characterized by accurate positioning, sensitivity and specificity. The pet can discover the overall condition of the whole body at a glance, and can realize the purpose of early discovery and diagnosis of diseases, which is applied to the early discovery and diagnosis of tumors, brain and heart diseases, etc. The main advantage of pet is the early discovery of hidden tiny foci. The main advantage of pet lies in the early detection of hidden tiny lesions. The examination is safe and effective and can be repeated. It can determine and find the precise location of the tumor. The examination is fast, generally about twenty minutes. Cost-effective, one examination can determine whether the tumor is benign or malignant and whether it has metastasis, and there is no need to do other examinations. So pet test is a better way to check tumor and heart and brain diseases, but the price is more expensive.