Pacemaker/implantable cardioverter-defibrillator dose in balloon high-dose-rate brachytherapy for breast cancer treatment.

PURPOSE

To retrospectively report pacemaker (PM)/implantable cardioverter-defibrillator (ICD) dose in balloon high-dose-rate (HDR) brachytherapy and provide distance-dose graph and table to approximately estimate the maximal device dose.

METHODS AND MATERIALS

For 3 patients (A, B, and C), PM/ICD was retrospectively contoured on planning computed tomography images and its maximal dose was extracted from a dose-volume histogram. The surface of 1cm expansion from balloon was prescribed to 34Gy and the inverse square law was dominant factor in dose calculation. Therefore, the maximal PM/ICD dose was approximately estimated from the distance-dose graph or table and compared with that of the treatment plan.

RESULTS

The minimal device-balloon surface distance was 10.9, 18.4, and 4.3cm for patient A, B, and C, respectively. The maximal dose estimated from the proposed table/graph was 2.1 vs. 1.61Gy for patient A, 0.87 vs. 0.49Gy for patient B, and 8.9 vs. 9.14Gy for patient C compared with that from the treatment plan.

CONCLUSIONS

Depending on the location of PM/ICD relative to the tumor bed, balloon HDR brachytherapy is feasible if the maximal dose is less than or equal to the dose limit. The proposed distance-dose graph and/or table enable to approximately predict the maximal device dose based on the measurement of minimal distance between lumpectomy and the device before balloon implantation for the suitability of balloon HDR brachytherapy.