SU-E-T-236: Brachytherapy for Breast Cancer Patients with Implanted Pacemeker, Using Multi Lumen Partial Breast Applicator.

PURPOSE

Discuss optimised Accelerated Partial Breast Irradiation (APBI) using a Strut-Adjused Volume Implant (SAVI) applicator for patients with implanted pacemeker, without overdosing or relocating the pacemaker.

METHODS

A right breast cancer patient with an in situ pacemaker (Medtronic model ADDR01) on the right side underwent breast conservative surgery and was referred for Partial Breast Irradiation (PBI) using Ir-192 High Dose Rate Brachytherapy. Preliminary estimation of the pacemaker dose from a pre-insertion CT study was about 8 % of the prescribed dose which exceeded the generally accepted dose of 2Gy. The challenge was to use a suitable applicator to treat the tumor bed and 1cm margin without exceeding the 2Gy limit to the pacemaker and the leads. A seven catheter SAVI device was selected and implanted in the right breast in an optimal direction and a 3D treatment plan was generated following a post insertion CT scan, using the Oncentra Brachy treatment planning system. Optimization tools namely anatomy based Inverse Planning Simulated Annealing (IPSA), and graphical optimization were utilized to load and optimize the dwell time in the catheters and reduce the dose received by the pacemaker. Device interrogation was conducted before and after the treatment. All operational parameters of the pacemaker were found to be normal.No change in the baseline reference values were observed.

RESULTS

Using the SAVI device it was possible to limit the pacemaker/ leads dose to less than 2 Gy. Target V100, V95 and V90 were 90.1%, 95.5% and 98.5% respectively. V150 and V200 being 18.6cc and 10.6cc respectively.Calculated average point doses on pacemaker assembly for ten fractions was 140cGy.

CONCLUSIONS

By combining the optimization tools of today's Brachytherapy planning system and a multilumen SAVI applicator, HDR partial breast irradiation can be safely delivered for breast cancer patients with in situ pacemaker, with out the fear of interrupting pacemaker functionality.