MammoSite Balloon Research Articles

A prospective feasibility study of MammoSite accelerated partial breast irradiation for early breast Cancer.

Accelerated partial breast irradiation is a potential alternative to standard whole breast irradiation, following breast-conserving surgery, in the management of breast cancer. The MammoSite applicator-based technique allows for the delivery of a higher dose of radiation to the tumour bed and adjacent area, over a shorter treatment period. To investigate the long-term feasibility of the MammoSite technique in early stage breast cancer in an Irish cohort. Sixty-two patients with early stage breast cancer were enrolled in this prospective study between November 2005 and October 2012 at the University Hospital Galway. A single-entry MammoSite applicator was inserted post-operatively. A CT scan was performed to assess the balloon to skin distance, the conformance of target tissue to balloon surface and balloon symmetry. A total dose of 34Gy was delivered over 10 fractions twice daily. Median follow-up was 10years. 91.9% (57/62) completed the full course of MammoSite treatment. Technical issues with the MammoSite balloon precluded three patients from completing the full course of treatment. On last follow-up, 6.4% (4/62) of patients had developed an ipsilateral breast recurrence. Half of these recurrences occurred more than 10years after the initial breast cancer treatment. The most common toxicities observed were fibrosis (67.7%), pain (61.3%) and skin erythema (35.5%). The use of the MammoSite technique, as an alternative to standard whole breast irradiation, is feasible in a typical Irish clinical setting with integrated multidisciplinary team input.

Verification of Balloon Integrity by Ultrasound Imaging in Accelerated Partial Breast Irradiation

<p class="cco-body"><em><span lang="EN-GB">Purpose</span></em><span lang="EN-GB">: An overview of the ultrasound imaging artifacts encountered in Mammosite balloon APBI is presented. Analysis of ultrasound measurement errors and the dosimetric impact of balloon leakage were used to determine whether clinically relevant changes in balloon size can be reliably detected. <em>Methods</em>: Ultrasound imaging of a Mammosite balloon phantom was performed to better understand measurement errors and accuracy. The dose to the prescription point as a function of balloon diameter was computed for different sized balloons. The results were compared to phantom measurements of balloon diameter versus filling volume to assess the dose change that would result from tissue moving inward with a shrinking balloon boundary. In APBI patients undergoing a course of 10 treatment fractions, the accuracy and variability of balloon size measured with ultrasound imaging was compared to CT. <em>Results</em>: Ultrasound artifacts combine to form a false image of the distal balloon boundary. Proper US probe orientation and choice of measurement point locations improved distance measurement accuracy. A 1 mm change in balloon diameter is measurable with ±0.1 mm error and corresponds to <4% change in dose 1 cm from the balloon. Measurement errors relative to CT averaged less than 1.4 mm and variability (standard deviation) over the course of treatment averaged 1.9 mm. <em>Conclusions</em>: Properly performed ultrasound image acquisition and analysis can detect dosimetrically relevant changes in the size of a leaking balloon. This study confirms that US imaging is a valid method of verifying APBI balloon integrity over the course of treatment.</span></p>

A Single-Site Retrospective, Nonrandomized Study of Accelerated Partial Breast Irradiation Brachytherapy for Early-Stage Breast Cancer Treatment to Evaluate Local Tumor Control, Cosmetic Outcome, and Toxicities.

To evaluate the efficacy and safety of the accelerated partial breast irradiation brachytherapy with a combination of applicators at a community hospital cancer center. Between 2005 and 2009, 120 patients with early-stage breast cancer were being followed after treatment with accelerated partial breast irradiation brachytherapy using MammoSite, single or multilumen balloon, or Contura multilumen balloon. After their lumpectomy surgery, each patient was treated with Ir-192 high-dose rate unit following radiation therapy oncology group 0413 guidelines. The patients had multiple follow-ups at 6 months, 1 year, 2 years, 3 years, or more. Based on the Harvard Breast Cosmesis Scale, 95.00% of patients described their cosmetic evaluation as the treated breast essentially the same as the opposite side (excellent) or minimal but identifiable effects were noticed from radiation (good). After a median follow-up of 36 months, the local recurrence rate was 1.66% and a disease-free survival is 98.3%. Forty-two patients reported 85 adverse events, which were fibrosis: 24.70%, hyperpigmentation: 20.00%, radiation skin reaction: 7.05%, seroma: 7.05%, breast pain: 7.05%, erythema: 5.88%, and other events were less than 5.00%. Of all the adverse events recorded, grade 1 to 3 events are 95.29% (n = 81), 2.35% (n = 2), and 2.35% (n = 2). There was no grade 4 or 5 events recorded. Our study has shown promising results for delivering radiation with MammoSite, single or multilumen balloon, or Contura multilumen balloon and has been successful in achieving local control in patients with early-stage breast cancer.

TU-F-CAMPUS-T-01: Potential of Using Cerium Oxide Nanoparticles (CONP) for Protecting Healthy Tissue During Accelerated Partial Breast Irradiation (APBI)

Purpose: The purpose of this research is to investigate the feasibility of using targeted cerium oxide nanoparticles (CONP) during APBI to protect healthy cells. Methods: In one approach, CONP are assumed to be incorporated in a micrometer-thick polymer film on the surface of routinely used mammosite balloon applicators for sustained in-situ release of the CONP. In case two, CONPs are administered directly into the lumpectomy cavity. The concentration of H₂O₂ produced by ionizing radiation was estimated from previously published work using short range linear extrapolation. The assessment of CONPs concentration required to absorb corresponding H₂O₂ to protect healthy tissue was calculated. Fick’s Second law of diffusion was employed to determine the initial concentration of CONP needed to achieve the minimum concentration for radioprotection at distance 1 cm and 2 cm from the lumpectomy cavity during APBI. The study was carried out for different nanoparticle sizes. Results: The initial concentration of CONPs required to get desired radioprotection concentration at 1 cm and 2 cm after 7 days was found to be 0.4089 mg per Kg and 59.7605 g per Kg respectively for 2 nm size nanoparticles. Using concentrations of 5 mg per kg of CONP that have been shown to be used to confer radioprotection (for about 7.97 Gy) in experiments it was observed that 4.5631, 8.5286, 10.9247, 22.0408, 43.6796 and 65.5618 number of days are required to achieve radioprotection at 1 cm for CONP of sizes 2 nm, 3.8 nm, 5 nm, 10 nm, 20 nm, 30 nm, respectively. Conclusion: Our preliminary results show that smaller size (2 nm and 3.8 nm) CONP would be suitable as radio protectant during APBI because they took a reasonable number of days, i.e. less than 10 days to reach tissues of 1 cm or 2 cm thickness.

TU-F-12A-08: Verification of APBI Balloon Integrity Using Ultrasound Imaging

Purpose: An overview of the ultrasound imaging artifacts encountered in Mammosite balloon APBI is presented. The goal was to determine whether clinically relevant changes in balloon size resulting from leakage can be detected by ultrasound imaging and also to compare the magnitude of size variations using both ultrasound and CT imaging. Methods: Ultrasound imaging of a Mammosite balloon phantom was performed to better understand measurement errors and accuracy. The dose to the prescription point as a function of balloon diameter was computed for different sized balloons. The results were compared to phantom measurements of balloon diameter versus filling volume to assess the dose change that would result from tissue moving inward with a shrinking balloon boundary. In APBI patients undergoing a course of 10 treatment fractions, an assessment was made of the variability and accuracy of balloon size measured with ultrasound imaging compared to CT. Results: Ultrasound artifacts combine to form a false image of the distal balloon boundary. Proper US probe orientation and choice of measurement point locations improves distance measurement accuracy. A 1 mm change in balloon diameter is measurable with ±0.1 mm error; this 1 mm change corresponding to <4% change in dose at a distance 1 cm from the balloon. In patients, the implanted balloon diameters ranged from 3.4 to 5.8 cm. Measurement errors relative to CT averaged less than 1.4 mm and variability (standard deviation) over the course of treatment averaged 1.9 mm. Conclusion: Complex and misleading image artifacts can be minimized by proper probe orientation, and accurate balloon diameter measurement requires consistent image analysis methods. Ultrasound imaging can detect dosimetrically relevant changes in the size of a leaking Mammosite balloon, therefore ultrasound imaging can be used for verification of balloon integrity over the course of APBI treatment.

WE-G-BRE-09: Targeted Radiotherapy Enhancement During Accelerated Partial Breast Irradiation (ABPI) Using Controlled Release of Gold Nanoparticles (GNPs)

Purpose: Several studies have demonstrated low rates of local recurrence with brachytherapy-based accelerated partial breast irradiation (APBI). However, long-term outcomes on toxicity (e.g. telangiectasia), and cosmesis remain a major concern. The purpose of this study is to investigate the dosimetric feasibility of using targeted non-toxic radiosensitizing gold nanoparticles (GNPs) for localized dose enhancement to the planning target volume (PTV) during APBI while reducing dose to normal tissue. Methods: Two approaches for administering the GNPs were considered. In one approach, GNPs are assumed to be incorporated in a micrometer-thick polymer film on the surface of routinely used mammosite balloon applicators, for sustained controlled in-situ release, and subsequent treatment using 50-kVp Xoft devices. In case two, GNPs are administered directly into the lumpectomy cavity e.g. via injection or using fiducials coated with the GNP-loaded polymer film. Recent studies have validated the use of fiducials for reducing the PTV margin during APBI with 6 MV beams. An experimentally determined diffusion coefficient was used to determine space-time customizable distribution of GNPs for feasible in-vivo concentrations of 43 mg/g. An analytic calculational approach from previously published work was employed to estimate the dose enhancement due to GNPs (2 and 10 nm) as a function of distance up to 1 cm from lumpectomy cavity. Results: Dose enhancement due to GNP was found to be about 130% for 50-kVp x-rays, and 110% for 6-MV external beam radiotherapy, 1 cm away from the lumpectomy cavity wall. Higher customizable dose enhancement could be achieved at other distances as a function of nanoparticle size. Conclusion: Our preliminary results suggest that significant dose enhancement can be achieved to residual tumor cells targeted with GNPs during APBI with electronic brachytherapy or external beam therapy. The findings provide a useful basis for developing nanoparticle-aided APBI, with potential to significantly reduce normal tissue/skin toxicity.

Extended (5-year) Outcomes of Accelerated Partial Breast Irradiation Using MammoSite Balloon Brachytherapy: Patterns of Failure, Patient Selection, and Dosimetric Correlates for Late Toxicity

Accelerated partial breast irradiation (APBI) with balloon and catheter-based brachytherapy has gained increasing popularity in recent years and is the subject of ongoing phase III trials. Initial data suggest promising local control and cosmetic results in appropriately selected patients. Long-term data continue to evolve but are limited outside of the context of the American Society of Breast Surgeons Registry Trial. A retrospective review of 157 patients completing APBI after breast-conserving surgery and axillary staging via high-dose-rate (192)Ir brachytherapy from June 2002 to December 2007 was made. APBI was delivered with a single-lumen MammoSite balloon-based applicator to a median dose of 34 Gy in 10 fractions over a 5-day period. Tumor coverage and critical organ dosimetry were retrospectively collected on the basis of computed tomography completed for conformance and symmetry. At a median follow-up time of 5.5 years (range, 0-10.0 years), the 5-year and 7-year actuarial incidences of ipsilateral breast control were 98%/98%, of nodal control 99%/98%, and of distant control 99%/99%, respectively. The crude rate of ipsilateral breast recurrence was 2.5% (n=4); of nodal failure, 1.9% (n=3); and of distant failure, 0.6% (n=1). The 5-year and 7-year actuarial overall survival rates were 89%/86%, with breast cancer-specific survival of 100%/99%, respectively. Good to excellent cosmetic outcomes were achieved in93.4% of patients. Telangiectasia developed in 27% of patients, with 1-year, 3-year, and 5-year actuarial incidence of 7%/24%/33%; skin dose >100% significantly predicted for the development of telangiectasia (50% vs 14%, P<.0001). Long-term single-institution outcomes suggest excellent tumor control, breast cosmesis, and minimal late toxicity. Skin toxicity is a function of skin dose, which may be ameliorated with dosimetric optimization afforded by newer multicatheter brachytherapy applicators and a more rigorous skin dose constraint of ≤100%.

SU-E-T-347: Dosimetric Effects Of Air Cavity Migration Through The Mammosite Multi-Lumen Balloon Treatments

Purpose: Study the dosimetric effects of air cavity migration through the mammosite multi-lumen balloon treatments. Methods: Using Multi-lumen mammosite had the advantage of shaping the dose around the balloon to get better coverage and less skin dose/hot spots. However, when there was air pocket around the balloon, the air pocket tended to move/change volume throughout the treatment. Since the dose distribution was usually asymmetric in treatment plans, the effects of air pocket need to be studied.Five(5) patients were selected for this study. For each patient, multi-lumen mammosite balloon was inserted into the cavity. Patient was then CTed and a treatment plan was created using Varian Eclipse TPS for delivery with Varian Varisource IX. PTV was created by expanding 1cm from balloon surface, 34 Gy were delivered in 10 fractions. The patient was CTed again after the last fraction before the balloon was extracted. The position of the balloon was checked to match the original CT. The treatment plan was recreated in the post-treatment CT.In order to evaluate the true difference, a new PTV was created in both original CT and post-treatment CT. The new PTV was 1 cm expansion from the cavity, excluding the entrance pathway, since these tissues were intended to be treated. Coverage and hot spots were evaluated with the new PTVs. Results: Through the treatment, air pocket normally will reduce volume and redistributed more evenly around the balloon, therefore coverage improved through the treatment. Since hot spots in multi-lumen cases were not symmetric, and during the planning, hot spots were usually targeted at air pocket if possible, at the end of the treatment, more tissue would receive high doses due to the air-pocket change. Conclusion: Care needs to be taken when there is air-pocket in treatment planning using multi-lumen mammosite treatment, especially the hot spots.

91 LONG TERM OUTCOMES AND RECURRENCE PATTERN FOLLOWING ACCELERATED PARTIAL BREAST IRRADIATION USING MAMMOSITE

Purpose/Objective: To evaluate: 1. The incidence of locoregional recurrence in early breast cancer treated by APBI using the MammoSite device in patients grouped according to ASTRO consensus panel 'suitable 'and 'cautionary' category. 2. The recurrence pattern in patients with 'triple negative tumor' (TN) (negative Estrogen, Progesterone receptor and Human Epidermal Growth factor (HER-2)) and the association and outcomes of African American, Hispanic ethnicity and ER negative tumor. Materials and Methods: Between June 2003 and December 2009, 83 post-menopausal patients:76 invasive ductal carcinoma (IDC), 7 ductal carcinoma in situ (DCIS), with diagnosis of early stage breast cancer and node negative status met our inclusion criteria for APBI using the single lumen MammoSite balloon catheter. Following a CT scan based 3D plan a dose of 3400cGy was prescribed in 10 fractions at distance of 1 cm from surface of balloon delivered twice daily, 6 hours apart using the high dose rate system. Patients were categorized as 4 groups: ASTRO consensus 'suitable', 'cautionary', TN and TN plus Her-2 positive ('High Risk'). Data on treatment outcome with for ipsilateral breast tumor recurrence (IBTR), tumor bed area failure (TBF), elsewhere failure in the same breast (EF), ipsilateral axilla failure (IAF) was analyzed. Results: There were 42/83 (51%) patients in the 'suitable' and 41/83 (49%) in the 'cautionary' group. TN was 11% (8/76) and 'High risk' was 24% (18/76) of invasive cancer patients. Mean age of invasive cancer patients was 72 years. Median follow-up for all 83 patients was 61 months; 'cautionary' group= 61 months; triple negative= 59; 'suitable' group=61 and 'High risk'= 59. Adjuvant chemotherapy was given in 18% (14/76) and hormones in 85% ER+ IDC patients. The locoregional control was 98.6%. IBTR that was EF occurred in 2/83 (2.4%) patients; one from the 'cautionary' group (ER-, HER2+) and another from the 'suitable' group (ER+, HER2-). IAF was seen in the first patient. There was a significant association between tumor grade and ethnicity with grade 3 tumors seen more in Hispanic and black women as compared to others (31% vs. 8%; p=0.03) in the invasive group. There was a higher proportion of ER-negative tumors seen among African American and Hispanics compared to other ethnicities (56.25% vs. 8.33%; p<.0001)

The impact of uncertainties associated with MammoSite brachytherapy on the dose distribution in the breast

The MammoSite radiation therapy system is a novel technique for treatment of patients with early‐stage breast cancer. It was developed to overcome the longer schedules associated with external‐beam radiation therapy. It consists of a small balloon (4 cm in diameter) connected to an inflation channel and a catheter for the passage of a high dose rate 192Ir brachytherapy source. The device is placed into the tumor resection cavity and inflated with a mixture of saline and radiographic contrast agent to a size that fills the cavity. A high dose rate 192Ir source is driven into the balloon center using a remote afterloader to deliver the prescribed dose at a point 1 cm away from the balloon surface. There are several uncertainties that affect the dose distribution in the MammoSite brachytherapy. They include source position deviation, balloon deformation, and the concentration of the contrast medium inside the balloon. The purpose of this study is to investigate the extent of the dose perturbation for various concentrations of the contrast medium in a MammoSite balloon using Monte Carlo simulations and thermoluminescent dosimetry. This study also combines the impact of these uncertainties on the MammoSite treatment efficacy. The current study demonstrates that the combined uncertainties associated with the MammoSite brachytherapy technique — up to the value of 2 mm balloon deformation, 1 mm source deviation, and 15% contrast concentration — have no impact on the tumor control probability.PACS number: 87.53.‐j

Analysis of Cosmesis, Dosimetric End Points and Local Control Using the Contura Multilumen and MammoSite Balloon Catheters for Accelerated Partial Breast Irradiation

Analysis of Cosmesis, Dosimetric End Points and Local Control Using the Contura Multilumen and MammoSite Balloon Catheters for Accelerated Partial Breast Irradiation

Accelerated partial breast irradiation

Whole breast irradiation (WBI) is the standard after breast conservation surgery. However, WBI in selected patients has been questioned. Accelerated partial breast irradiation (APBI) focuses treatment on the lumpectomy bed. Many modalities of delivering APBI have been developed: multicatheter interstitial brachytherapy, MammoSite balloon catheter, single insertion multicatheter devices, three-dimensional conformal external-beam radiation therapy and intraoperative techniques. Numerous studies of APBI have demonstrated excellent local control and cosmetic outcomes in early-stage breast cancer patients.

MammoSite multilumen catheter: Dosimetry considerations

To explore the dosimetric advantages of the new MammoSite multilumen (ML) balloon for breast brachytherapy treatment compared to conventional single lumen (SL) device plan. Patients deemed appropriate for accelerated partial breast irradiation (APBI) were implanted with the MammoSite ML balloon. Two plans were generated in each patient for the same target coverage (PTV_EVAL) and dose to normal structures were plotted. The first plan used only the central single lumen with single-dwell position (SL), and the second plan (ML) was generated using the other lumens of the device. Dose distributions of the SL and ML plans were compared. For the same PTV_EVAL, the ML balloon improved dose coverage at the tip and base of the applicator compared to SL plan. The skin and rib doses were reduced using the ML plan versus SL plan for the same PTV_EVAL in-patient 2, where the skin-balloon distance was 7 mm and the rib-balloon distance was <1 cm. For patient 1, the skin and rib distances were greater than 1 cm and the ML plan did not further minimize the dose to normal structures. In our initial experience, dosimetric goals can be better achieved using the ML MammoSite balloon when normal structures (skin and ribs) are close to PTV_EVAL with a distance of <7 mm and rib distance of <1 cm. The multiple lumen of ML balloon can optimize dose and reduce excessive dose to rib and skin and therefore minimize the long-term toxicities of rib discomfort, skin fibrosis and fat necrosis.

Use of MammoSite balloon brachytherapy for early-stage breast cancer

Use of MammoSite balloon brachytherapy for early-stage breast cancer

An Inter-comparison of Differing Applicators for HDR Vaginal Cuff Brachytherapy with a Focus on the Potential Use of the Contura Device

HDR brachytherapy is commonly used for vaginal cuff treatment. The vast majority of radiation therapy facilities, according to a recent ABS survey, used the single channel HDR vaginal cylinder. The potential use and efficacy of Mammosite balloon in HDR vaginal cuff brachytherapy (VCB) has been recently reported. The major disadvantage to using a single channel applicator is the pronounced anisotropy seen at the vaginal apex. In this study, we have evaluated and inter-compared the single channel 3 cm diameter HDR cylinder, the 4-channel Wright vaginal applicator, the single lumen Hologic Mammosite, and the multi lumen Senorex Contura brachytherapy balloon in VCB.

A dosimetric comparison of the Contura multilumen balloon breast brachytherapy catheter vs. the single-lumen MammoSite balloon device in patients treated with accelerated partial breast irradiation at a single institution

Purpose A comparison of dosimetric findings in 33 patients treated with the Contura multilumen balloon (SenoRx Inc., Irvine, CA) (C-MLB) breast brachytherapy catheter vs. 33 patients treated with the MammoSite (Hologic Inc., Bedford, MA) (MS) at a single institution to deliver accelerated partial breast irradiation (APBI) was performed. Methods and Materials CT-based 3-dimensional planning with dose optimization was completed. APBI treatment of 34 Gy in 3.4 Gy fractions was delivered. Endpoints analyzed included: ( 1) The percentage of the prescribed dose (PD) covering the planning target volume (PTV), ( 2) the maximum skin dose as a percentage of the PD, ( 3) the maximum rib dose as a percentage of the PD, and ( 4) the V150 and V200. Results The C-MLB was placed more frequently in patients with closer skin spacing (<7 mm) and rib spacing (<7 mm) than in MS patients (45.5% vs. 12.1%, p = 0.0057 and 57.6 vs. 33.3, p = 0.0131, respectively). Despite closer skin spacing, the overall median skin dose was significantly lower in C-MLB patients (112% of the PD vs. 134%, p = 0.0282). No statistically significant differences in the V150 or V200 were observed. In patients with very limited rib spacing (<4 mm), the C-MLB delivered significantly lower rib doses than the MS (144% of the PD vs. 191%, p = 0.0107). In all clinical scenarios, coverage of the PTV with the C-MLB was either equal to or significantly better than with the MS ( p = 0.0024). Conclusion The C-MLB catheter produced clinically significant improvements in dosimetric endpoints (e.g., reduced skin and rib doses and improved PTV coverage) in most clinical scenarios.

Outcomes After Accelerated Partial Breast Irradiation in Patients With ASTRO Consensus Statement Cautionary Features

To evaluate outcomes among women with American Society for Radiation Oncology (ASTRO) consensus statement cautionary features treated with brachytherapy-based accelerated partial breast irradiation (APBI). Between March 2001 and June 2006, 322 consecutive patients were treated with high-dose-rate (HDR) APBI at the University of Wisconsin. A total of 136 patients were identified who met the ASTRO cautionary criteria. Thirty-eight (27.9%) patients possessed multiple cautionary factors. All patients received 32 to 34 Gy in 8 to 10 twice-daily fractions using multicatheter (93.4%) or Mammosite balloon (6.6%) brachytherapy. With a median follow-up of 60 months, there were 5 ipsilateral breast tumor recurrences (IBTR), three local, and two loco-regional. The 5-year actuarial rate of IBTR was 4.8%±4.1%. The 5-year disease-free survival was 89.6%, with a cause-specific survival and overall survival of 97.6% and 95.3%, respectively. There were no IBTRs among 32 patients with ductal carcinoma in situ (DCIS) vs. 6.1% for patients with invasive carcinoma (p=0.24). Among 104 patients with Stage I or II invasive carcinoma, the IBTR rate for patients considered cautionary because of age alone was 0% vs. 12.7% in those deemed cautionary due to histopathologic factors (p=0.018). Overall, we observed few local recurrences among patients with cautionary features. Women with DCIS and patients 50 to 59 years of age with Stage I/II disease who otherwise meet the criteria for suitability appear to be at a low risk of IBTR. Patients with tumor-related cautionary features will benefit from careful patient selection.

Effects of breast‐air and breast‐lung interfaces on the dose rate at the planning target volume of a MammoSite® catheter for Yb‐169 and Ir‐192 HDR sources

To study the effects of the breast-air and breast-lung interfaces on the absorbed dose within the planning target volume (PTV) of a MammoSite balloon dose delivery system as well as the effect of contrast material on the dose rate in the PTV. The Monte Carlo MCNP5 code was used to simulate dose rate in the PTV of a 2 cm radius MammoSite balloon dose delivery system. The simulations were carried out using an average female chest phantom (AFCP) and a semi-infinite water phantom for both Yb-169 and Ir-192 high dose rate sources for brachytherapy application. Gastrografin was introduced at varying concentrations to study the effect of contrast material on the dose rate in the PTV. The effect of the density of the materials surrounding the MammoSite balloon containing 0% contrast material on the calculated dose rate at different radial distances in the PTV was demonstrated. Within the PTV, the ratio of the calculated dose rate for the AFCP and the semi-infinite water phantom for the point closest to the breast-air interface (90 degrees) is less than that for the point closest to the breast-lung interface (270 degrees) by 11.4% and 4% for the HDR sources of Yb-169 and Ir-192, respectively. When contrast material was introduced into the 2 cm radius MammoSite balloon at varying concentrations, (5%, 10%, 15%, and 20%), the dose rate in the AFCP at 3.0 cm radial distance at 90 degrees was decreased by as much as 14.8% and 6.2% for Yb-169 and Ir-192, respectively, when compared to that of the semi-infinite water phantom with contrast concentrations of 5%, 10%, 15%, and 20%, respectively. Commercially available software used to calculate dose rate in the PTV of a MammoSite balloon needs to account for patient anatomy and density of surrounding materials in the dosimetry analyses in order to avoid patient underdose.

Initial Clinical Experience With the Strut-Adjusted Volume Implant (SAVI) Breast Brachytherapy Device for Accelerated Partial-Breast Irradiation (APBI): First 100 Patients With More Than 1 Year of Follow-Up

The Strut-Adjusted Volume Implant (SAVI; Cianna Medical, Aliso Viejo, CA) is a multichannel single-entry brachytherapy device designed to allow dose modulation to minimize normal tissue dose while simultaneously maximizing target coverage. This is the first report on the initial 102 patients with nearly 2 years of median follow-up. One hundred two patients were treated at two institutions. Data were collected on eligibility and dosimetry and followed for toxicity and recurrence. The median follow-up is 21 months. Overall dosimetry is outstanding (median percent of target volume receiving 90% of the prescription dose was 95.9%, volume of target receiving 150% of the prescription dose was 27.8 mL, and volume of target receiving 200% of the prescription dose was 14.0 cm(3)). No devices were pulled prior to treatment completion. For patients with a skin bridge of less than 7 mm, the maximum median skin dose was 280 cGy (median percent of target volume receiving 90% of the prescription dose was 95.2%, volume of target receiving 150% of the prescription dose was 25.8 cm(3) and volume of target receiving 200% of the prescription dose was 12.7 mL). For patients with both chest wall and skin of less than 7 mm, the maximum median lung dose was 205 cGy with simultaneous skin dose of 272 cGy. The rate of telangiectasia was 1.9%. Grade 1 hyperpigmentation developed in 10 patients (9.8%) and Grade 2 fibrosis in 2 patients (1.9%). There were 2 symptomatic seromas and 2 cases of asymptomatic fat necrosis (1.9%). Of the patients, 27% were not eligible for MammoSite balloon brachytherapy (Hologic, Inc., Marlborough, MA) and 5% were not eligible for any balloon brachytherapy. The recurrence rate was 1%. The SAVI appears to safely allow an increase in eligibility for APBI over balloon brachytherapy or three-dimensional conformal radiation, highlighting the outstanding device flexibility to maximize the target dose and minimize the normal tissue dose. The device was well tolerated by patients.

Angiosarcoma following MammoSite® partial breast irradiation

Angiosarcoma is a rare tumor of endothelial origin which commonly arises in small blood or lymphatic vessels. Its development in the treated breast following adjuvant external beam radiation is also rare. To our knowledge, there are no reported cases in the literature or MammoSite registry which describe the occurrence of angiosarcoma in the treated breast following MammoSite brachytherapy. This is a case report of a 74 year old female who developed angiosarcoma 4 years after receiving MammoSite balloon brachytherapy following surgical resection of a T1mic N0 M0 infiltrating ductal carcinoma.