[{"from": "human", "value": "Generate a molecule based on this description. The molecule is the acetate salt of the radioisotope carbon-11. Although the mechanism is unclear, carbon-11 acetate preferentially accumulates in tumor tissue, serving as a tracer for imaging tumors with positron emission tomography (PET). (NCI04)"}, {"from": "gpt", "value": "[C][11C][=Branch1][C][=O][O]"}]