Comparative dosimetric findings using accelerated partial breast irradiation across five catheter subtypes

Abstract

PurposeAccelerated 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 materialsA 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.ResultsSAVI 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).ConclusionPTV 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.

Unusual complications after MammoSite brachytherapy: out‐of‐field rib fracture and Mondor's disease

“…From these data, a D max of 120-125% of the PD has been proposed, 4,5 wherein the preferred D max should be as low as 100%. 6,7 Thus, although it was unsurprising that ribs 4 and 5 were fractured in this case report, the finding of rib 6 was unexpected. The patient had no known risk factors, such as primary or secondary osteoporosis.…”

“…Thus, most studies have reported rib D max as a chest wall/rib parameter, with some measuring the balloon‐to‐rib distance as well. From these data, a D max of 120–125% of the PD has been proposed, 4,5 wherein the preferred D max should be as low as 100% 6,7 …”

“…Although there have been recommended skin constraints, the consensus on chest wall constraints remains unsettled. Recent reports have documented chest wall toxicity as a rare complication of APBI in the context of a high maximum point dose (D max ) 3–7 . In contrast, a D max of less than or equal to the prescribed dose (PD) was found to be safe from the occurrence of rib fractures 6,7 …”

“…Recent reports have documented chest wall toxicity as a rare complication of APBI in the context of a high maximum point dose (D max ). [3][4][5][6][7] In contrast, a D max of less than or equal to the prescribed dose (PD) was found to be safe from the occurrence of rib fractures. 6,7 Here, we reported the first case of an out-of-field rib fracture, with a D max of <50% of the PD, and Mondor's disease in a 61-year-old woman after MammoSite brachytherapy.…”

Relationship among different skin dose definitions in high-dose-rate (HDR) balloon breast brachytherapy

“…Accelerated partial-breast irradiation using balloon highdose-rate (HDR) brachytherapy has provided excellent outcomes, comparable tumor control, and low toxicity rates when compared to whole-breast irradiation [1][2][3][4][5]. One of the important outcomes following balloon breast HDR brachytherapy is skin toxicity, and the maximum skin dose is a key dosimetric parameter in balloon HDR breast brachytherapy treatment planning [2,[6][7][8][9]. Hence, the skin maximum point dose was limited to ≤ 145% of the prescribed dose in the use of a single-lumen MammoSite® balloon applicator (Hologic Inc., Bedford, MA, USA) [10].…”