Preoperative CT for postoperative radiotherapy planning in breast cancer.

Introduction: The exact location of the original tumor should be known for a targeted increase in the dose to the tumor bed after breast cancer surgery. Therefore, at our site, we perform CT examinations of patients in the radiation position before breast cancer surgery.

Methods: Preoperative native CT scans were performed in the patients in the planning position for radiotherapy; these data were fused with standard planning CT for boost irradiation. We evaluated whether the tumor was accurately identifiable in preoperative CT scans. We also contoured one irradiation volume in the standard planning CT scans and the other in the fusion CT scans with preoperative examination, and compared these volumes.

Results: Out of the total number of 554 patients, we were able to identify the exact location of the breast tumor in 463 cases (83.6 %). In a group of 50 randomly selected patients, the clinical target volume for the boost dose to the postlumpectomy cavity was changed in 20 patients (40%) - decreased in 9 cases (18%) and increased in 11 cases (22%).

Conclusion: As shown by the results of our study, preoperative CT in the planning position can be used in patients with confirmed breast cancer. This method allows us to more accurately locate the tumor bed and thus more accurately draw the target volume for boost irradiation. We confirmed that preoperative CT had an impact on the size of the target volume.