PET-CT means Positron Emission Computed Tomography. After PET-CT, if a patient finds a lump with radioactive concentration and considers it to be a tumor, a biopsy must be done before receiving treatment to diagnose the benignity and malignancy of the tumor, its stage, whether it is metastatic or not, and to guide the treatment. PET-CT has various advantages, such as very fine and accurate examination of lung cancer and brain cancer, but it is relatively weak for examination of tumors of cavity organs, such as stomach cancer, intestinal cancer and bladder cancer. However, it is relatively weak for tumors of cavity organs, such as stomach, intestine and bladder cancer. In addition, PET-CT is not sensitive to lesions less than 5 mm in diameter, which can easily cause false negative results, and combining it with biopsy can improve the accuracy of the examination. Biopsy is the examination of biopsies, by which isolated tissues and cells are filmed, observed and diagnosed. Biopsy is a common clinical examination involving various tissues and organs, such as gastroscopy and colonoscopy, puncture of parenchymal organs such as lung tissue and liver, and extraction of pleural fluid and ascites for cytological examination, and therefore has a high degree of accuracy.