Intraoperative radiotherapy (IORT) serves to administer large doses of radiation during surgery. During surgery, healthy tissue/organs can be shifted out of the radiation beam, thereby reducing toxicity. Moreover, being visible, the lesion can be targeted with greater precision. The advantages of IORT are:
a) It enhances the surgical result because it eliminates eventual tumor residue.
b) It enhances the antitumoral effect of radiotherapy because much higher radiation levels are achieved compared with external irradiation alone.
c) It reduces the interval between tumor removal and irradiation: consequently, residual cells do not have time to grow.

Intraoperative therapy was first used in the 1920s, but the instrumentation available at that time limited its use. The major obstacle to IORT was that the patient, under anesthesia and with the surgical wound open, was transported from the operating theatre to the radiotherapy service and return to complete the operation, with consequent organizational problems, and increased risk of infection. Now in some institutes the procedure the procedure is completed in or very near the bunker.