Detection of metastasis of γ-IR-treated mice using bioluminescence imaging. Xenograft formation and γ-IR treatment were performed as described in Materials and methods. Images were detected over a week between weeks 3 and 9 of radiation treatment. Bioluminescence imaging of metastasis was performed after mice were anesthetized with isoflurane in a live state. (A) Bioluminescence images of metastasis in the lungs. The upper Figure represents the schedule of bioluminescence imaging and lower box indicates the number of metastases and total mice. Bioluminescence images of metastasis in the lung. The horizontal number indicates the week and the vertical number represents each mouse. Ex vivo images including brains were also detected in the last week (mouse numbers 1, 2, and 4). (B) Bioluminescence images of metastasis in the intestine. The horizontal number indicates the week and the vertical number represents each mouse. (C and D) Relationship analysis of fLuc activity and tumor volume of mice (numbers 1 and 5) in the lung metastasis group.