Skin dose estimation using virtual structures for Contura Multi-Lumen Balloon breast brachytherapy.
PURPOSE
To propose a workflow that uses ultrasound (US)-measured skin-balloon distances and virtual structure creations in the treatment planning system to evaluate the maximum skin dose for patients treated with Contura Multi-Lumen Balloon applicators.


METHODS AND MATERIALS
Twenty-three patients were analyzed in this study. CT and US were used to investigate the interfractional skin-balloon distance variations. Virtual structures were created on the planning CT to predict the maximum skin doses. Fitted curves and its equation can be obtained from the skin-balloon distance vs. maximum skin dose plot using virtual structure information. The fidelity of US-measured skin distance and the skin dose prediction using virtual structures were assessed.


RESULTS
The differences between CT- and US-measured skin-balloon distances values had an average of -0.5 ± 1.1 mm (95% confidence interval [CI] = -1.0 to 0.1 mm). Using virtual structure created on CT, the average difference between the predicted and the actual dose overlay maximum skin dose was -1.7% (95% CI = -3.0 to -0.4%). Furthermore, when applying the US-measured skin distance values in the virtual structure trendline equation, the differences between predicted and actual maximum skin dose had an average of 0.7 ± 6.4% (95% CI = -2.3% to 3.7%).


CONCLUSIONS
It is possible to use US to observe interfraction skin-balloon distance variation to replace CT acquisition. With the proposed workflow, based on the creation of virtual structures defined on the planning CT- and US-measured skin-balloon distances, the maximum skin doses can be reasonably estimated.
['Huang|YuHuei Jessica|YJ|', 'Su|Fan-Chi Frances|FF|', 'Gaffney|David K|DK|', 'Kokeny|Kristine E|KE|', 'Zhao|Hui|H|', 'Rassiah-Szegedi|Prema|P|', 'Salter|Bill J|BJ|', 'Poppe|Matthew M|MM|']
D001918:Brachytherapy D001940:Breast D001943:Breast Neoplasms D057785:Catheters D005260:Female D006801:Humans D011874:Radiometry D011879:Radiotherapy Dosage D011880:Radiotherapy Planning, Computer-Assisted D012867:Skin D014057:Tomography, X-Ray Computed D016217:Ultrasonography, Mammary
Skin dose Contura Brachytherapy Accelerated partial breast irradiation