Fig. 1

A ¹⁸F-FDG-PET/CT image at the time of primary diagnosis: the red line delineates the volumes with the SUV thresholds of 2.5 and the green line delineates the volumes with 50% of the SUVmax. B ¹⁸F-FDG-PET/CT image at the time of diagnosis of recurrence: the black line delineates the volumes with the SUV thresholds of 2.5. C The deformation coregistration ¹⁸F-FDG-PET/CT image of primary and recurrent images. (A1,B1,C1) Patient 1: Cross-failure rate of V_recur∩pri = 8.5%, out-field recurrence; Cross-failure rate of V_recur∩high = 6.29%, out-side recurrence. (A2,B2,C2) Patient 2: Cross-failure rate of V_recur∩pri = 47.76%, marginal-field recurrence; Cross-failure rate of V_recur∩high = 9.68%, out-side recurrence. (A3,B3,C3) Patient 3: Cross-failure rate of V_recur∩pri = 100%, in-field recurrence; Cross-failure rate of V_recur∩high = 66.73%, in-side recurrence. (A4,B4,C4) Patient 4: Cross-failure rate of V_recur∩pri = 97.15%, in-field recurrence; Cross-failure rate of V_recur∩high = 32.36%, marginal-side recurrence