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Purpose: Accelerated partial breast irradiation (APBI) with balloon and strut adjusted volume implants (SAVI) show promising results with excellent tumor control and minimal toxicity. Knowing the factors that contribute to a high skin dose, rib dose, and D95 coverage may reduce toxicity, improve tumor control, and help properly predict patient outcomes following APBI., Methods and Materials: A retrospective analysis of 594 patients treated with brachytherapy based APBI at a single institution from May 2008 to September 2014 was grouped by applicator subtype. Patients were treated to a total of 34 Gy (3.4 Gy x 10 fractions over 5 days delivered BID) targeting a planning target volume (PTV) 1.0 cm beyond the lumpectomy cavity using a high dose rate source., Results: SAVI devices had the lowest statistically significant values of DmaxSkin (81.00 ± 29.83), highest values of D90 (101.50 ± 3.66), and D95 (96.09 ± 4.55). SAVI-mini devices had the lowest statistically significant values of DmaxRib (77.66 ± 32.92) and smallest V150 (18.01 ± 3.39). Multi-lumen balloons were able to obtain the smallest V200 (5.89 ± 2.21). Strut-based applicators were more likely to achieve a DmaxSkin and a DmaxRib less than or equal to 100 %. The effect of PTV on V150 showed a strong positive relationship (p < .001). PTV and DmaxSkin showed a weak negative relationship in multi-lumen applicators (p = .016) and SAVI-mini devices (p < .001). PTV and DmaxRib showed a weak negative relationship in multi-lumen applicators (p = .009), SAVI devices (p < .001), and SAVI-mini devices (p < .001)., Conclusion: PTV volume is strongly correlated with V150 in all devices and V200 in strut based devices. Larger PTV volumes result in greater V150 and V200, which could help predict potential risks for hotspots and resulting toxicities in these devices. PTV volume is also weakly negatively correlated with max skin dose and max rib dose, meaning that as the PTV volumes increase one can expect slightly smaller max skin and rib doses. Strut based applicators are significantly more effective in keeping skin and rib dose constraints under 125 and 100 % when compared to any balloon based applicator.

Purpose: Non-melanoma skin cancers of the face are at high-risk for local recurrence and metastatic spread. While surgical interventions such as Mohs microsurgery are considered the standard of care, this modality has the potential for high rates of toxicity in sensitive areas of the face. Catheter flap high-dose-rate (HDR) brachytherapy has shown promising results, with high rates of local control and acceptable cosmetic outcomes. Material and methods: Patients with non-melanoma skin cancers (NMSC) located on the face were treated with 40 Gy in 8 fractions, given twice weekly via catheter flap HDR brachytherapy. Clinical target volume (CTV) included the visible tumor plus a margin of 5 mm in all directions, with no additional planning target volume (PTV) margin. Results: Fifty patients with 53 lesions on the face were included, with a median follow-up of 15 months. All were considered high-risk based on NCCN guidelines. Median tumor size and thickness were 18 mm and 5 mm, respectively. Median PTV volume and D90 were 1.7 cc and 92%, respectively. Estimated rate of local control at twelve months was 92%. Three patients (5%) experienced acute grade 2 toxicity. Two patients (4%) continued to suffer from chronic grade 1 skin toxicity at 12 months post-radiotherapy (RT), with an additional two patients (4%) experiencing chronic grade 2 skin toxicity. Forty-nine lesions (92%) were found to have a good or excellent cosmetic outcome with complete tumor remission. Conclusions: CT-based flap applicator brachytherapy is a valid treatment option for patients with NMSC of the face. This modality offers high rates of local control with acceptable cosmetic outcomes and low rates of toxicity. [ABSTRACT FROM AUTHOR]