S82 Abstracts / Brachytherapy 13 (2014) S15eS126

location can be challenging for NIBB but the majority of patients are stillcandidates. Surgical clips are very helpful in defining the tumor bed forboost and greatly increase the likelihood of eligibility for NIBB.

PD77

Dosimetric Comparison and Early Clinical Outcomes of Interstitial

Versus Strut Assisted Volume Implant (SAVI) for Accelerated Partial

Breast Irradiation

Mitchell Kamrava, MD, Sang-June Park, PhD, Ben Noor, BS, D. Jeffrey

Demanes, MD. University of California Los Angeles, Los Angeles, CA.

Purpose: There are several brachytherapymethods available for acceleratedpartial breast irradiation (APBI). Interstitial tube and button (T&B) has beenutilized the longest but newer single entry channel devices have becomemorewidely adopted because they are considered easier to deploy. The SAVIdevice is the most similar to the interstitial approach because it hasmultiple struts that sit on the edge of the lumpectomy cavity. We comparedour recent contemporaneous experience with (dosimetry and early clinicaloutcomes) with these two devices.Materials and Methods: We prospectively collected data on patientstreated with either SAVI or T&B APBI at our institution between 2010and 2013. NSABP B39 target volumes and dosimetry constraints wereapplied. The mean dose was 34 Gy delivered twice daily for 10 fractions.Dosimetry parameters included: PTV volume (cc), minimum cavity toskin distance (mm), Target: D90 (%), V90 (%), V95 (%), V100 (%),V150 (%), V200 (%), Dose Heterogeneity Index (DHI) (%), Breast:V100% (cc), V150% (cc), V200% (cc), DHI (%), V50% (%), Normaltissue: skin D0.1cc (%), Pectoralis D0.1 cc (%), Ribs D0.1cc (%),Ipsilateral lung D0.1 cc (%). A paired t-test was used to detect significantdifferences between the methods.Results: There were 71 patients (37 SAVI and 34 TþB) whose mean agewas 61 (þ/-11) years. Average tumor size was 1.2 (þ/- 0.6) cm.Histologies were 39 IDC (55%), 4 ILC (6%),4 ITC (6%), and 24 DCIS(34%). Tumor markers were positive as follows: ER 96%, PR 90%, andHer2 4%. According to ASTRO consensus guidelines the patients weresuitable 25%, cautionary 54% and unsuitable 21%. Adjuvant anti-estrogen therapy was administered to 62% and adjuvant chemotherapy to4% of patients. Table 1 presents a dosimetry comparison of T&B versusSAVI. With a median followup of 20.0 months there has been 1 regionalrecurrence, but no local or distant failures.Conclusions: There are significant differences between T&B and SAVIdosimetry particularly with repect to the DHI both within the target andthe normal breast. As expected with this cohort of patients with shortfollowup there have been no local recurrences noted. Longer followup isneeded to determine whether the observed dosimetric differences between

Average � SD SAVI (n534) T&B (n531) P value

PTV Volume (cc) 71 � 29 59 � 31 0.08

Cavity to skin distance (mm) 7 � 7 8 � 3 0.40

Target D90 (%) 102 � 4 105 � 6 0.009

Target V90 (%) 98 � 2 98 � 2 0.25

Target V95 (%) 96 � 3 97 � 3 0.13

Target V100 (%) 92 � 4 94 � 5 0.06

Target V150 (%) 44 � 4 24 � 3 !0.001

Target V200 (%) 22 � 3 9 � 2 !0.001

Target DHI (%) 52 � 3 74 � 4 !0.001

Breast V100 (cc) 70 � 23 71 � 34 0.84

Breast V150 (cc) 31 � 10 17 � 9 !0.001

Breast V200 (cc) 15 � 4 7 � 3 !0.001

Breast DIII (%) 55 � 2 75 � 2 !0.001

V50 (%) 19 � 7 19 � 9 0.76

Skin D0.1cc (%) 91 � 11 70 � 11 !0.001

Pectoralis D0.1 cc (%) 84 � 28 77 � 44 0.41

Ribs D0.1 cc (%) 61 � 20 48 � 22 0.01

Ipsilateral lung D0.1 cc 45 � 15 34 � 15 0.002

T&B versus SAVI are clinically meaningful in terms of local control and/or cosmetic outcomes.

PD78

Clinical Experience with a Miniature Accelerated Partial Breast

Irradiation Device: A 5-Year Single Institution Comprehensive

Study

Serban Morcovescu, MS, DABR1, Jeffery Douglas Morton, MD1, Y. Elle

Boleware, MS1, Perry Kerri, MD2. 1Radiation Oncology, Texas Oncology

Denton, Denton, TX; 2North Texas Hospital, Denton, TX.

Purpose: Strut-based applicators have become an alternative to balloon-type applicators in accelerated partial breast irradiation (APBI), and wereincreasingly used at our practice since early 2008. The applicator studied(Cianna Medical, Aliso Viejo, CA), is the smallest of its kind (6-1mini),and it has skin), chest wall bridge, and the maximum doses to criticalstructures (skin and chest-wall). PTV-to-PTV_EVAL volume reductionscoefficients (VR) were also evaluated and discussed, in light of theirimpact on reported conformity indexes (CI) and dose homogeneityindexes (DHI). A detailed dosimetric analysis of different patient strata(grouped on a skin bridge 5 mm intervals) is provided. The implanttechnique - device entry and orientation vs. breast side and lumpectomycavity location in breast quadrants - is also discussed from a dosimetricpoint of view.Results: Lumpectomy cavity volumes averaged 8.4�1.3cc. PTV_EVALand PTV volumes averaged 44.7�7.9cc and 49.9�3.4cc, respectively.V90 values averaged 98.8�1.7% (TG43) of the PTV_EVAL volume.Similarly, V95 averaged 97.8�2.5%, and V100 averaged 95.3�4.8%across the entire cohort of patients. The V150 ‘‘hotspots’’ averaged20.6�6.1cc, while V200 averaged 18.8�6.6cc. The average minimumskin distance was 13.5mm, but the applicator was used in patients wherethe skin bridge was as low as 1mm. The average maximum skin dose was72.8% of the prescription dose. The average minimum rib bridge was15.2mm, with the shortest of less than 0.3mm, and the average maximumdose to the chest wall of 90.5% of the prescription dose. The TG43formalism was employed on all dosimetric evaluations.Conclusions: The SAVI6-1mini strut-based device proves to be a highlyadaptable and versatile APBI solution for patients with reduced breastand lumpectomy cavity volumes, and skin and/or rib bridges. Inside theframework of a detailed and clear QA program, when it is appropriatelyelected as the APBI device of choice, optimally implanted, andcomprehensively monitored during the course of treatment, this deviceindeed offers a very effective and highly reproducible tool for thetreatment of complex breast cancer cases.

PD79

Feasibility of Permanent Breast Seed Implants in British Columbia:

Preliminary Dosimetric and Safety Results

Yen Pham, MSc1, Michelle Hilts, PhD2, Deidre Batchelar, PhD2, Juanita

M. Crook, MD3, Will Ansbacher, PhD1, Hosam Kader, MD4. 1Medical

Physics, BC Cancer Agency - Vancouver Island Centre, Victoria, BC,

Canada; 2Medical Physics, BC Cancer Agency - Centre of Southern

Interior, Kelowna, BC, Canada; 3Radiation Oncology, BC Cancer Agency

- Centre of Southern Interior, Kelowna, BC, Canada; 4Radiation

Oncology, BC Cancer Agency - Vancouver Island Centre, Victoria, BC,

Canada.

Purpose: To present preliminary results from a prospective study todetermine the feasibility and safety of permanent breast seed implants asa viable treatment option for women with early stage breast cancer inBritish Columbia.Materials and Methods: Two centers within the BC Cancer Agency arecollaborating on a prospective single arm feasibility study on the use ofpermanent breast seed implants (PBSI) using palladium-103.Confirmation of the technical feasibility and safety of PBSI is required

S83Abstracts / Brachytherapy 13 (2014) S15eS126

before progressing to a larger prospective evaluation of the technique. Thirtywomen (age greater than 60 years, seroma maximum equivalent diameterless than 3cm) who have undergone breast conserving surgery with lowrisk of local recurrence will be accrued. The Centre for the SouthernInterior (CSI) uses an ultrasound guided technique while the VancouverIsland Centre (VIC) uses external markers and a backpointer bridgeguided technique. Both use CT planning with MIM Symphony andundertake a common peripheral weighted planning strategy aiming toprovide greater than 98% coverage by the 90Gy prescription dose to aPTV defined by seroma plus 1.25cm margin (cropped to skin andchestwall). Post-implant dosimetry is assessed on a evaluative PTV(PTVeval) defined by seroma plus 0.5cm margin using CT scans obtainedon day of implant (day 0) as well as one month post-implant. Acute skintoxicity is reported at initial followup (day 30). Radiation safety of PBSIwas evaluated using partner issued dosimeters (first 10 cases, worn for 30days). Patient satisfaction is assessed at 1 week and 12 weeks postimplant via oral questionnaire.Results: To date, PBSI plans have been designed for twenty-one womenwho consented to the study. Seroma volumes ranged from 0.6 - 20.2cc(median 5.5cc) and the resulting PTVs (range: 29.4 - 114.2cc (median61.0cc) were covered using an average of 80�22 seeds in 19�5 needles.Pre-plan dosimetry goals were well met: mean V100 and V150 of96.8�2.0% and 68.1�5.9% were obtained. Of these 21, one case has yetto be treated, one was cancelled due to an infection and one was notcompleted due to technical limitations. For the remaining 18 cases,PTVeval DVH results (day 0) are (mean�SD): 92.5�9.8%, 90.0�11.4%and 67.6�15.6% for V90, V100 and V150 respectively and 95.6�28.3Gyfor D90%. Day 30 results are similar. The observed spread in these figuresstems largely from the initial implants; results clearly show improvedquality with experience. The corresponding PTVeval means for the last 8cases implanted (4 at each centre) are: 98.3�1.8%, 96.6�3.2% and75.7�10.0% respectively. D90% is 111.7�12.8Gy. Max skin dose anddose to 1cm2 skin surface area ranged from 2 - 213Gy (median 57Gy) and2 - 74Gy (median 39Gy), respectively. Side effects reported in followupfor most cases have been none to minimal (some mild telangiectasia)however minor moist desquamation has occurred in two cases.There were no radiation safety concerns with PBSI. This was confirmed bypartner badge measurements, which all read well below the 5mSv caregiverlimit, and patient radiation survey readings performed on day 0 and day 30.Overall, patients report being extremely satisfied at both questionnaire timepoints.Conclusions: The techniques used by both centres are yielding equallygood clinical coverage of the lumpectomy bed, particularly following aninitial learning curve. Minimal side effects have been reported andcosmetic results have been excellent overall. The patients who havecompleted therapy are extremely satisfied with their treatment experienceand initial outcomes. These preliminary results indicate that PBSI is asafe and appealing treatment option for women with low risk breastcancer in BC.

PD80

Increasing Efficiency in Multi-Catheter High-Dose-Rate

Brachytherapy for Breast Cancer

Deidre Batchelar, PhD, Michelle Hilts, PhD, Matthew Schmid, MSc,

Rezwan Chowdhury, MD. Medical Physics, BC Cancer Agency - Southern

Interior, Kelowna, BC, Canada.

Purpose: To implement novel software tools for HDR breast brachytherapyin order to a) reduce the time required to determine desired catheterpositions prior to insertion; b) reduce the chance for error in catheterpositions; and c) reduce the time required for contouring whiledeveloping the treatment plan.Materials and Methods: We have applied software tools, originallydeveloped by MIM Software Inc. for seed brachytherapy and externalbeam contouring, to two stages in the multi-catheter HDRbrachytherapy process: a) selection of catheter positions and b)contouring for treatment planning. To begin the implant procedure, theaffected breast is placed in compression in a template that will guide

catheter placement. A CT scan is acquired and the target contoured tofacilitate identification of catheter positions required to produce anacceptable dose distribution. This process demands the ability to viewthe maximum target projection (MTP) on the template. In our standardHDR planning software it is time consuming to orientate the images andto define the MTP. Furthermore, there is no straightforward means ofprojecting a virtual template onto the images or of directly obtaining arecord of the template locations identified as optimum for catheterplacement. Using the MIM Symphony module for breast seed implants,re-orientating the images to a ‘‘needle-eye-view’’ is trivial and, otherthan manually contouring the seroma, all contouring tasks can beautomated by creating a MIM workflow. Most importantly, ourtemplates are configured in MIM Symphony and these can be projectedvirtually across all image planes. We can then insert virtual seed needlesinto the template and scan through the entire volume to assess theappropriateness of the chosen locations. Further, a plan report print-outrecords template locations selected for catheter insertion, acts as achecklist in application of anesthesia and catheters and ensures thatthere are no transcription errors affecting planned needle locations.When contouring for planning, we use deformable registration (MIMMaestro) to fuse an eligibility scan to the planning scan. The pre-implant seroma is transferred to the planning scan where it is assessedand modified by the radiation oncologist. We then use a second MIMworkflow to generate the requisite contours. The planning scan and RTstructure set are then transferred to the planning system. The impacts ofthese changes were assessed by timing the original and modifiedprocesses.Results: Pre-planning the catheter locations took 8 minutes on averageusing MIM, reduced from an average of 35 minutes. The registration andcontouring processes for planning were reduced to 8 minutes from 75minutes.Conclusions: Multi-catheter HDR brachytherapy has recently beenimplemented at our center under the auspices of a trial aiming todetermine the feasibility of establishing this as a standard treatment at acommunity cancer centre. As such, we have dual motivation to ensure ourprocesses are as efficient and robust as possible. Firstly, for preplanning itis imperative that the needle positions be determined as quickly aspossible as the breast is under compression, and also that the needlelocations are communicated correctly to the implant team. Additionally,reducing overall planning time is cost effective from a personnel point ofview and makes the technique more feasible. Using tools developed forother radiotherapy processes has allowed us to substantially reduce thetime required for planning multi-catheter HDR breast brachytherapytreatments.

PD81

Accelerated Partial Breast Irradiation with Multicatheter High-

Dose-Rate Brachytherapy: Feasibility and Results in a Private

Practice Cohort

Richard Benjamin Young, BA, Clinton A. Medbery III, MD, Marianne M.

Young, MD, Astrid E. Morrison, MD. Radiation Oncology, Frank C. Love

Cancer Institute, Oklahoma City, OK.

Purpose: To report results/outcomes of use of multicatheter interstitialhigh-dose-rate (HDR) brachytherapy (BT) to deliver accelerated partialbreast irradiation (APBI) in a large cohort of women treated in a threephysician private practice setting over 10 years 9 months.Materials and Methods: Two hundred forty-one selected patients with Tis-2 N0-1mic breast cancer without an extensive intraductal component andwith negative surgical margins were treated after breast conservingsurgery (BCS) with APBI using HDR BT. Three physicians performedthe procedures as part of a comprehensive radiation oncology practice.Median patient age was 61. Dosage regimen was initially 34Gy in 10fractions over 4 elapsed days; subsequently 32Gy in 8 fractions over 3-4elapsed days was used. Target volume was the surgical resection bed with1.5-2.0 cm margin. Ultrasound guidance was used in 231 cases andmammographic stereotactic guidance in 10 cases. Overall medianfollowup was 67.8 months and 67.4 months in surviving patients. Local