Inclusion Criteria:  Among the subjects, the subjects are selected according to the following criteria:  Those who have been diagnosed with gastric cancer and are scheduled for robotic total gastrectomy; A person who is 18 years of age or older and able to make independent judgment on their own; A person who can have a CT scan according to the established protocol;  Before participating in the clinical trial, an interview was conducted in an independent space, the purpose and contents of the clinical trial were fully explained, and the consent to participate in this study was voluntarily given (approved by the institutional research ethics review committee) and those who signed.  For reference, internal employees and immediate family members can also participate in this study unless there is a special reason for exclusion.  Exclusion Criteria:  If any of the following exclusion criteria are met among the subjects, participants will be excluded from this clinical trial:  Vulnerable subjects (those who lack medical ability, or are illiterate, pregnant, newborns, minors (under 18), etc.); Persons who cannot have a CT scan according to the prescribed protocol prior to gastric cancer surgery (contrast agent allergy, creatinine 1.5 times the normal maximum, claustrophobia, etc.); Persons whose major artery/venous structure in the stomach or abdominal cavity has been altered due to previous surgery (due to gastric cancer or other abdominal surgery); Persons with residual gastric cancer with a history of gastric surgery; Persons who did not consent to this study or who withdrew consent.