Accurate verification of balloon rotation correction for the Contura multilumen device for accelerated partial breast irradiation.

PURPOSE

To validate a method of accurately confirming the orientation of the Contura multilumen balloon catheter before each fraction and to determine if any residual device rotation remains after adjustment.

METHODS AND MATERIALS

Sixteen patients underwent CT scans before each treatment with accelerated partial breast irradiation. Before acquisition of CT scans for planning, each patient had a skin mark drawn to align with Lumen #1 (the Contura [SenoRx, Inc., Irvine, CA] has a black line on the shaft of the applicator to identify this lumen). In addition, a CT spot marker was used as a fixed reference point on the patient's skin. CT markers (used for lumen identification and reconstruction) were also used as additional reference points for distance measurements. The distances measured from the CT spot marker to the three reproducible points on the CT markers were used for balloon rotation verification. These measurements were performed for each daily fraction on reproducible CT axial views.

RESULTS

Three hundred eighteen measurements were obtained. Median residual rotation for all cases was 0.2mm (standard deviation=0.797). Later fractions and skin spacing changes over time were associated with slightly greater residual rotation (Fraction #1 vs. Fraction #10, 0.1 vs. 0.3mm, p=0.05; and skin spacing change ≤2 vs. >2mm, 0.2 vs. 0.5mm, p=0.0019, respectively).

CONCLUSIONS

These results confirm external alignment of a skin mark with Lumen #1 (on the Contura catheter) is an accurate and reliable method to align the balloon before treatment and that no significant internal device rotation (0.2mm) is likely to occur.