Intraoperative breast radiation therapy with image guidance: Findings from CT images obtained in a prospective trial of intraoperative high-dose-rate brachytherapy with CT on rails

A Novel Form of Breast Intraoperative Radiation Therapy With CT-Guided High-Dose-Rate Brachytherapy: Results of a Prospective Phase 1 Clinical Trial

“…A series of CT images were obtained using the CT-on-rails system. The images were reviewed by the breast surgeon, radiation oncologist, and medical physicist, and the balloon and breast tissue were adjusted as needed to improve tissue conformity [21]. Patients participating in the trial in the post-pathology cohort proceeded through the same process as above, however without BCS.…”

“…Intraoperative imaging of any modality is uncommon in breast IORT and no other systems utilize CT-based imaging. The CT images provide the ability to evaluate applicator placement and facilitate customized treatment planning [21] . Compared to other forms of IORT, HDR brachytherapy allows for superior target volume coverage and a higher prescription dose delivered to the adjacent breast tissue without excessive balloon surface dose [20].…”

“…While these techniques are likely beneficial compared to no image-guidance, they do not provide the same 3-dimensional analysis afforded by CT imaging. In our experience, the use of CT leads to changes in applicator positioning in nearly a quarter of breast IORT cases [21] and in this study the PTV_eval was modified based off of CT imaging in a majority of patients. For the two patients in this trial whose treatment time exceeded the predefined feasibility criteria, it is noteworthy that this was related to the need for the adjustment of the brachytherapy applicator.…”

“…Additionally, we are working with collaborators to assess feasibility of CT-HDR-IORT in centers without integrated HDR brachytherapy suites. Although our method of image-guided IORT with HDR brachytherapy addresses recognized technological and dose limitations of IORT [20,21,37,38], inherent limitations of IORT remain such as the lack of final pathology results for surgical margins and M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 13 nodal status. While we attempted to improve on the latter through a pre-IORT sentinel lymph node evaluation, this results in two separate surgical procedures for the patient.…”

Intraoperative radiation therapy for breast cancer patients: current perspectives

“…The PB-IORT technique described the above attempts to overcome this limitation by obtaining an intraoperative CT scan, which allows for applicator position adjustment before treatment is delivered. Published data found that the benefit of intraoperative CT was not trivial, in that it identifies actionable findings in breast IORT, including residual tumor or errors in applicator positioning, in 24% of patients 38. These images are also used to aid in optimizing radiation planning and performing dosimetry calculations to organs at risk.…”