Study of Tumor Perfusion with 11C-Acetate during Radiotherapy Treatment in Head and Neck Cancer

• Main Authors: Bentourkia, M., Wang, C.S., Lavallee, E., Al-Enezi, M.S.
• Format: Conference Proceeding
• Language: English
• Subjects: Ganglia; Head; Neck; Protocols; Radiation therapy; Radiotracer; Semiconductor detectors
• ISSN: 2577-0829
• DOI: 10.1109/NSSMICRTSD49126.2023.10338112

Radiotherapy of head and neck cancer in adult humans is generally conducted with the same protocol in terms of radiation dose and number of treatments. The response to the treatment is known to depend on the individuals, and on the stage of the cancer at the start of the treatment. In the last decade, some authors suggested to estimate the tumor response to the treatment at certain time during the treatment, then to adjust the radiation dosage typically to hypoxic tumors. In the present work, we report the assessment of tumor perfusion with the 11C-Acetate radiotracer before and after 4 weeks of radiotherapy treatment. Four volunteers were recruited and imaged twice with a PET/CT scanner for head and neck cancer in dynamic mode for 30 min. A compartmental model was applied to the tumor time-activity curves (TACs). The tumors were first identified on the initial 11C-Acetate image. The images were decomposed in blood and tissue with the independent component analysis (ICA) technique. Since the tumors have different behavior in each patient, the values are reported individually with the rate constants and the influx rate constant. Also, the images show the shrinkage of the tumor after 4 weeks of treatment. Typically, the rate constants K1, k2 and k3 were found, for a single patient, before treatment: tumor: 0.0350, 0.3241, 0.2289; Ganglion: 0.0494, 0.5955, 0.3830, and at mid-treatment: Tumor: 0.7642, 0.2482, 0.0147; Ganglion: 0.6501, 0.2958, 0.0541. By calculating the influx rate constant Ki=K(1)*k(3)/(k(2)+k(3)), this gave a gain in perfusion of 2.95 and 5.2, respectively for the tumor and the ganglion. In conclusion, the assessment of the perfusion is more adequate to estimate tumor response to treatment, tumor hypoxia and necrosis.