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内容記述 |
The aim of this study was to identify a hypoxic area in tumor imaging without the use of radiopharmaceuticals. Since tumor hypoxia status is an important indicator to evaluate effects of the treatment, frequent monitoring of the hypoxia is required during a radiation treatment period. However, PET using hypoxia radiopharmaceuticals is impractical to perform in every fractionated irradiation. On the other hand, it is possible to evaluate tumor hypoxia by estimating blood flow washout rates by detecting irradiation produced positron-emitters in range-verification or beam-monitoring PET. Therefore, it is necessary to confirm whether the blood flow supply and kinetics of the irradiation produced positron emitters (washout) in the tumor can reflect the tumor oxygen status. This study aimed to obtain evidence in hypoxic tumor rat models by comparing results from beam-monitoring PET and conventional hypoxia PET. Methods: Glioma C6 cancer cells were transplanted into nude rats. Tumors were irradiated with a 12C ion beam, and beam-monitoring PET was performed using a high sensitivity total-body small-animal PET system. A compartment model was applied to the kinetic data of the irradiation produced positron emitters. Then, 18F-FAZA PET imaging of the hypoxia area of the tumor of the same rat was performed. Results: The parametric maps of washout rate obtained with beam-monitoring PET were in good agreement with 18F-FAZA-PET images. Conclusion: This study demonstrated the biological washout-rate obtained in beam-monitoring PET was used to diagnose tumor hypoxia. |
