The project's objective is to recruit patients with clinically confirmed or suspected small cell lung cancer, breast cancer, nasopharyngeal carcinoma and other tumours for 68Ga-FL-031 PET imaging and 18F-FDG PET imaging. The histopathology of biopsy or surgical specimens was taken as the final diagnostic criteria, and the presence or absence of tumour lesions was confirmed by the aforementioned imaging. The location and nature of the lesion, and the presence or absence of metastasis, were then judged. The objective was to analyse and clarify the diagnostic efficacy of 68Ga-FL-031 PET imaging for the aforementioned malignant tumours. The objective of this study is to analyse the correlation between the 68Ga-FL-031 PET imaging tumour tissue uptake value and the tumour tissue immunohistochemical staining SSTR2 target expression.

Inclusion Criteria:

1. The subject or their legal representative is permitted to sign the informed consent form.
2. The subject has committed themselves to adherence to the prescribed research procedures and to cooperation in the implementation of the entire study process.
3. Adult patients (aged 18 years or older), irrespective of gender
4. Patients with a clinical suspicion or confirmed diagnosis of small cell lung cancer, breast cancer, nasopharyngeal carcinoma, and other tumours (for which supporting evidence is provided in the form of serum-related tumour markers, ultrasound, CT, MRI and other image data, and histopathological examination)
5. The patient is generally in good condition
6. It is mutually agreed upon by all parties involved that the designated specimen shall be utilised for the purposes of this study.

Exclusion Criteria:

1. The patient or his legal representative is unable or unwilling to sign the informed consent
2. The patient is unable to cooperate with the implementation of the whole process research
3. The patient has been diagnosed with acute systemic diseases and electrolyte disorders
4. Pregnant women or lactating women, etc
5. In the event of other circumstances being deemed by the investigator to be unsuitable for participation in the study, such patients must be excluded on the basis of their known intolerance to SSTR2 targeted substances.