30-69 years old healthy participants in Zhongshan

Diagnostic Test: P85-Ab,EBNA1-IgA,and VCA-IgA. Detect P85-Ab, EBNA1-IgA, VCA-IgA for all participants and select serological high-risk participants DiagnosticTest: dual-energy CT, endoscopy and biopsy. serological high-risk participants will refer to dual-energy CT, endoscopy and biospy

To compare the sensitivity [actual number of nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy / (actual number of nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy + number of nasopharyngeal cancers in the non-nasopharyngeal cancer population considered by dual-energy CT or endoscopy)] and specificity [actual number of non-nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy / ( actual number of non-nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy + number of non-nasopharyngeal cancers in the nasopharyngeal cancer population considered by dual-energy CT or endoscopy)] of dual-energy CT and endoscopy in the diagnosis of nasopharyngeal carcinoma, and to determine which test is more accurate in detecting nasopharyngeal carcinoma from the population

To compare the positive predictive value [actual number of nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy / (actual number of nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy + number of non-nasopharyngeal cancers in the nasopharyngeal cancer population considered by dual-energy CT or endoscopy )] and negative predictive value [actual number of non-nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy / (actual number of non-nasopharyngeal cancers in the population considered by dual-energy CT or endoscopy + number of nasopharyngeal cancers in the non-nasopharyngeal cancer population considered by dual-energy CT or endoscopy)] of dual-energy CT and endoscopy in the diagnosis of nasopharyngeal carcinoma