This is a prospective, single-center, open-label clinical study designed to evaluate the safety, biodistribution, radiation dosimetry, and diagnostic performance of [68Ga]Ga-FFD PET imaging. The study consists of two cohorts: healthy volunteers and adult patients with histologically or clinically confirmed malignant solid tumors. Healthy volunteers will undergo serial PET imaging to evaluate tracer biodistribution, pharmacokinetics, and radiation dosimetry. Patients will undergo [68Ga]Ga-FFD PET imaging in addition to standard-of-care ^18F-FDG PET imaging for assessment of lesion detection and diagnostic performance. Safety will be evaluated through adverse event monitoring, vital signs, laboratory tests, physical examinations, and electrocardiography. Diagnostic performance will be assessed using histopathology, conventional imaging, and clinical follow-up as the reference standard.

This first-in-human study evaluates the clinical performance of [68Ga]Ga-FFD, a novel PET radiotracer for molecular imaging of malignant tumors. Healthy volunteers will undergo serial whole-body PET imaging after a single intravenous administration of [68Ga]Ga-FFD to characterize biodistribution, organ uptake, pharmacokinetics, and radiation dosimetry. Adult patients with malignant solid tumors will undergo [68Ga]Ga-FFD PET/CT and standard-of-care ^18F-FDG PET/CT imaging. Diagnostic performance, including lesion detection and patient-based diagnostic accuracy, will be compared between the two imaging modalities. Radiation dosimetry will be estimated using time-activity curves and the OLINDA/EXM software based on the MIRD methodology. Safety assessments will include adverse events, laboratory evaluations, electrocardiography, physical examinations, and vital signs.

Inclusion Criteria:

• Written informed consent obtained before any study-specific procedures. Adults aged 18 years or older.
• Healthy volunteers or patients with histologically, cytologically, or clinically confirmed malignant solid tumors.
• ECOG performance status of 0-1 for patients.
• Clinical indication for ^18F-FDG PET/CT imaging (patient cohort only).
• Adequate organ function.
• Willing and able to comply with all study procedures.

Exclusion Criteria:

• Pregnant or breastfeeding women.
• Known hypersensitivity to gallium-containing radiopharmaceuticals or any component of the investigational product.
• Clinically significant uncontrolled cardiovascular, hepatic, renal, hematologic, neurological, or psychiatric disease.
• Active uncontrolled infection requiring systemic treatment.
• Receipt of investigational drugs or participation in another interventional clinical study within 30 days before enrollment.
• Previous anticancer therapy that does not satisfy the protocol-defined washout period (patient cohort only).
• Inability to undergo PET/CT imaging or comply with study procedures. Any condition that, in the investigator's judgment, would compromise participant safety or interfere with study assessments.