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Background and Purpose: The upgrade of major equipment can be disruptive to clinical operations and introduce risk as policy and procedures need to adapt to new technical possibilities and constraints. We describe here the transition from GammaMedPlus-iX to Bravos in a busy brachytherapy clinic, involving four afterloaders across two sites., Material and Methods: Our clinic employs three high-dose-rate remote afterloaders in four dedicated treatment vaults at the main site and a fourth afterloader at a regional location. Of more than 600 new HDR treatment plans performed annually, most are planned and treated intraoperatively. Most treatments are for prostate cancer, followed by GYN, intraoperative brachytherapy, GI, and other sites. Applicators used include vendor-provided applicators as well as third party applicators and in-house 3D-printed devices to provide interstitial, intracavitary, intraluminal, and surface treatments. All applicators were commissioned according to recommended guidelines. The choice of tolerances and the design of new procedures were informed by current guidelines and leveraged new HDR afterloader functionalities. A review of clinical operations in the 4 months postupgrade was conducted to evaluate the feasibility of new tolerances and the effectiveness of new procedures., Results: The procedures outlined improved and standardized afterloader QA and treatment protocols with clear actionable steps for staff to follow to ensure treatments are delivered as planned. Re-commissioning of applicators yielded results similar to those previously reported by other investigators. A review of initial treatment data revealed that in one case, due to the implementation of tight tolerances, obstruction near the tip of the channel was detected and corrected prior to treatment. It confirms that the implementation of the tolerances adopted is feasible and effective in flagging treatment deviations., Conclusion: Enhanced procedures and QA processes were implemented successfully. We established clear actionable steps to follow by staff to ensure that treatments are delivered accurately., (Copyright © 2024 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

The initial favorable efficacy and safety profile for Alpha DaRT have been demonstrated (NCT04377360); however, the longer-term safety and durability of the treatment are unknown. This pooled analysis of four prospective trials evaluated the long-term safety and efficacy of Alpha DaRT for the treatment of head and neck or skin tumors. A total of 81 lesions in 71 patients were treated across six international institutions, with a median follow-up of 14.1 months (range: 2-51 months). Alpha DaRT sources were delivered via a percutaneous interstitial technique and placed to irradiate the tumor volume with the margin. The sources were removed two to three weeks following implantation. A complete response was observed in 89% of treated lesions (n = 72) and a partial response in 10% (n = 8). The two-year actuarial local recurrence-free survival was 77% [95% CI 63-87]. Variables, including recurrent versus non-recurrent lesions, baseline tumor size, or histology, did not impact long-term outcomes. Twenty-seven percent of patients developed related acute grade 2 or higher toxicities, which resolved with conservative measures. No grade 2 or higher late toxicities were observed. These data support the favorable safety profile of Alpha DaRT, which is currently being explored in a pivotal US trial.

Background: Diffusing alpha-emitters Radiation Therapy ("DaRT") is a promising new modality for the treatment of solid tumors. Interstitial sources containing 224 Ra are inserted into the tumor, producing alpha particles via the decay of 224 Ra and its daughters. The alpha particles are able to produce a "kill region" of several mm due to the diffusion of the alpha-emitting atoms. The Diffusion-Leakage (D-L) model has been proposed to describe the movement of the alpha-emitters used in DaRT in tumor tissue., Purpose: To date, estimating the dose delivered under the D-L model has been accomplished with numerical solutions based on finite difference methods, namely DART1D and DART2D, as well as with asymptotic expressions for the long time limit. The aim of this work is to develop a flexible method of finite elements for solving the D-L model and to validate prior solutions of the D-L model., Methods: We develop a two-dimensional finite element solution to the D-L model implemented using the FEniCS software library. Our approach solves the variational formulation of the D-L equations on an unstructured mesh of triangular Lagrangian elements. We calculate the local dose in the mid- and axial planes of the source and validate our results against the one- and two-dimensional solutions obtained using the previously proposed numerical scheme, DART1D and DART2D. We use our model to estimate the change in dose in the source midplane as a function of the physical parameters used in the D-L model., Results: The local dose at the end of a 30 day treatment period estimated by our numerical method differs from DART1D and DART2D by less than 1% in the source midplane and less than 3% along the source axis over clinically relevant distances, with the largest discrepancies in high gradient areas where the Finite Element Method (FEM) mesh has a higher element density. We find that within current experimentally estimated ranges for D-L model parameters, the dose in the source midplane at a distance of 2 mm can vary by over a factor of 3., Conclusions: The 2D finite element model reproduces the calculated dose obtained with DART1D and DART2D under the assumptions D-L model. The variation in predicted dose within current experimental ranges for model parameters suggests the necessity of further studies to better determine their statistical distributions. Finally, the FEM model can be used to calculate dose from DaRT in a variety of realistic 2D geometries beyond the D-L model., (© 2023 American Association of Physicists in Medicine.)

Importance: Patients with recurrent or unresectable skin cancers have limited treatment options. Diffusing alpha-emitter radiation therapy (DaRT), a novel solid tumor management strategy using alpha-particle interstitial brachytherapy, may address this challenge., Objective: To evaluate the feasibility and safety of using DaRT to manage recurrent or unresectable skin cancers., Design, Setting, and Participants: This prospective cohort study of patients who received a 2-week to 3-week treatment course and were followed up for 24 weeks after treatment during 2021 and 2022 at 2 sites in the US. Patients with malignant skin tumors or soft tissue tumors were recruited if they had limited treatment options for tumors recurrent after prior surgery or external beam radiotherapy or unresectable tumors., Intervention: Patients underwent DaRT to deliver a physical dose of 10 Gy (equivalent weighted dose of 200 CGE) to the tumor., Main Outcomes and Measures: Feasibility of the DaRT procedure was evaluated based on the ability of investigators to successfully deliver radiation to the tumor. Patients were followed up for adverse events (AEs) for 24 weeks and for tumor response by physicians' physical examination and imaging 12 weeks after device removal., Results: This study included 10 participants with recurrent or unresectable skin cancer (median [IQR] age, 72 [68-75] years; 6 males [60%]; 4 females [40%]). Six patients (60%) had recurrent disease, and 4 (40%) had tumors that were deemed unresectable. Tumors were located on the nose, chin, eyelid, scalp, neck, trunk, and extremities. Median (range) tumor volume before treatment was 2.1 cm3 (0.65-12.65 cm3). The mean (SD) prescription dose coverage of the gross tumor volume was 91% (2.8%) with all tumors having coverage of 85% or more. No device-related grade 3 AEs were noted. Common AEs were grade 1 to 2 erythema, edema, and pruritus. At 12 weeks following treatment, there was a 100% complete response rate. Nine of 10 complete responses (90%) were confirmed by CT imaging., Conclusions and Relevance: This cohort study suggests the feasibility and preliminary safety of DaRT in the management of recurrent or unresectable skin cancers. The favorable safety profile and high response rates are promising. A US trial for marketing approval based on this pilot study is under way., Trial Registration: ClinicalTrials.gov Identifier: NCT04377360.

Purpose: This study reports clinical experience and feasibility of using a 2-dimensional (2D)-kV image system with online intervention in the ultrafractionated stereotactic body radiation treatment (UF-SBRT) of prostate cancer., Methods and Materials: Fifteen patients with prostate cancer who had a low- to intermediate-risk marker implanted received UF-SBRT with online 2D-kV image tracking and a manual beam interruption strategy with a 2-mm motion threshold. A total of 180 kV paired setup images and 1272 intrabeam 2D-kV images were analyzed to evaluate the setup deviation and intratreatment target deviation. Correlation of expected treatment interruptions with a set of parameters (eg, image and treatment time; direction of deviation) was performed (Spearman test). A subset of the data from 22 fractions was re-evaluated to check the differences in analysis results between using the planning position and using the pretreatment setup position as a reference. Margins based on the derived system and random errors were calculated to evaluate the feasibility of the workflow in ensuring prostate coverage during treatment., Results: Mean target motion in 3D propagated from 1.0 mm (setup at 0 minutes) to 2.0 mm (beam on at 7 minutes) to 2.4 mm (end at 13.5 minutes). Out of 75 fractions, 50 were found to require beam interruption. Interruption had a strong correlation with prostate motion along the longitudinal direction and had moderate correlation with prostate motion along the vertical direction and the prostate's treatment starting position along vertical and longitudinal directions. Using the pretreatment position as a reference for intrabeam monitoring, the magnitude of motion deviation from the reference position was reduced by 0.3 mm at a vertical direction and 0.4 mm at lateral and longitudinal directions. The calculated 3D margin to ensure target coverage was 3.7 mm, 4.6 mm, and 5.0 mm in lateral, vertical, and longitudinal directions, respectively., Conclusions: Prostate motion propagated over time. It is feasible to use a 2D-kV online intrabeam monitoring system with a proper intervention scheme to perform UF-SBRT for prostate cancer., (Copyright © 2022 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: The purpose of this study was to examine the effect of departmental planning techniques on appropriate in-vivo source tracking error thresholds for high dose rate (HDR) prostate brachytherapy (BT) treatments, and to determine if a single in-vivo source tracking error threshold would be appropriate for the same patient anatomy., Methods: The prostate, rectum, and urethra were contoured on a single patient transrectal ultrasound (TRUS) dataset. Anonymized DICOM files were disseminated to 16 departments who created an HDR prostate BT treatment plan on the dataset with a prescription dose of 15 Gy in a single fraction. Departments were asked to follow their own local treatment planning guidelines. Source positioning errors were then simulated in the 16 treatment plans and the effect on dose-volume histogram (DVH) indices calculated. Change in DVH indices were used to determine appropriate in-vivo source tracking error thresholds. Plans were considered to require intervention if the following DVH conditions occurred: prostate V100% < 90%, urethra D0.1cc > 118%, and rectumtt Dmax > 80%., Results: There was wide variation in appropriate in-vivo source tracking error thresholds among the 16 participating departments, ranging from 1 to 6 mm. Appropriate in-vivo source tracking error thresholds were also found to depend on the direction of the source positioning error and the endpoint. A robustness parameter was derived, and found to correlate with the sensitivity of plans to source positioning errors., Conclusions: A single HDR prostate BT in-vivo source tracking error threshold cannot be applied across multiple departments, even for the same patient anatomy. The burden on in-vivo source tracking devices may be eased through improving HDR prostate BT plan robustness during the plan optimisation phase., (© 2022 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)

Purpose: This is a multi-institutional report on inter-observer and inter-instrument variation in the calibration of the absorbed dose rate for a planar 32 P beta emitting brachytherapy source. Measurement accuracy is essential since the dose profile is steep and the source is used for the treatment of tumors that are located in close proximity to healthy nervous system structures., Methods and Materials: An RIC-100 32 P source was calibrated by three institutions using their own equipment and following their standard procedures. The first institution calibrated the source with an electron diode and EBT3 film. The second institution used an electron diode. The third institution used HD810 film. Additionally, each institution was asked to calibrate the source using an electron diode and procedure that was shared among all institutions and shipped along with the radiation source. The dose rate was reported in units of cGy*min -1 at a water equivalent depth of 1 mm., Results: Close agreement was observed in the measurements from different users and equipment. The variation across all diode detectors and institutions had a standard deviation of 1.8% and maximum difference of 4.6%. The observed variation among two different diode systems used within the same institution had a mean difference of 1.6% and a maximum variation of 1.8%. The variations among film and diode systems used within the same institution had a mean difference of 2.9% and a maximum variation of 4.3% CONCLUSIONS: The absorbed dose rate measurement protocol of the planar beta-emitting 32 P source permits consistent dosimetry across three institutions and five different electron diode and radiochromic film systems. The methodologies presented herein should enable measurement consistency among other clinical users, which will help ensure high quality patient treatments and outcomes analysis., (Copyright © 2021 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: This study evaluated outcomes associated with a high-dose-rate (HDR) brachytherapy boost combined with stereotactic body radiation therapy (SBRT) for patients with higher-risk localized prostate cancer., Materials and Methods: We identified 101 patients with National Comprehensive Cancer Network high-risk, unfavorable intermediate-risk, or favorable intermediate-risk with probable extra-prostatic extension treated with HDR brachytherapy (15 Gy x 1 fraction) followed by SBRT (5 Gy x 5 daily fractions to the prostate and/or seminal vesicles and/or pelvic lymph nodes). Androgen deprivation therapy was used in 55.4% of all patients (90% of high-risk, 33% of intermediate-risk). Toxicities according to Common Terminology Criteria for Adverse Events (CTCAE) v4.0 and International Prostate Symptom Scores were prospectively documented at each followup visit. Biochemical relapse was defined as PSA nadir +2ng/mL., Results: The median follow-up time after SBRT was 24.1 months. No grade ≥3 toxicities were observed. The incidence of acute and late grade 2 gastrointestinal toxicities was both 0.99%. Acute and late grade 2 genitourinary (GU) toxicities were observed in 5.9% and 9.9%, respectively. Median time to a grade 2 GU toxicity was 6 months with a 14% 2-year actuarial rate of grade 2 GU toxicity. Median International Prostate Symptom Scores at 24 months was not significantly different than baseline (6 vs. 5; p = 0.24). Inclusion of pelvic lymph nodes and absence of a rectal spacer were significantly associated with more frequent grade ≥1 GU toxicity, but not grade ≥2 GU or gastrointestinal toxicity. The 2-year biochemical relapse free survival was 97%., Conclusions: HDR brachytherapy combined with SBRT was associated with a favorable early toxicity profile and encouraging cancer control outcomes., (Copyright © 2021 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To quantitatively evaluate through automated simulations the clinical significance of potential high-dose rate (HDR) prostate brachytherapy (HDRPB) physics errors selected from our internal failure-modes and effect analysis (FMEA)., Methods and Materials: A list of failure modes was compiled and scored independently by 8 brachytherapy physicists on a one-to-ten scale for severity (S), occurrence (O), and detectability (D), with risk priority number (RPN) = SxOxD. Variability of RPNs across observers (standard deviation/average) was calculated. Six idealized HDRPB plans were generated, and error simulations were performed: single (N = 1722) and systematic (N = 126) catheter shifts (craniocaudal; -1cm:1 cm); single catheter digitization errors (tip and connector needle-tips displaced independently in random directions; 0.1 cm:0.5 cm; N = 44,318); and swaps (two catheters swapped during digitization or connection; N = 528). The deviations due to each error in prostate D90%, urethra D20%, and rectum D1cm 3 were analyzed using two thresholds: 5-20% (possible clinical impact) and >20% (potentially reportable events)., Results: Twenty-nine relevant failure modes were described. Overall, RPNs ranged from 6 to 108 (average ± 1 standard deviation, 46 ± 23), with responder variability ranging from 19% to 184% (average 75% ± 30%). Potentially reportable events were observed in the simulations for systematic shifts >0.4 cm for prostate and digitization errors >0.3 cm for the urethra and >0.4 cm for rectum. Possible clinical impact was observed for catheter swaps (all organs), systematic shifts >0.2 cm for prostate and >0.4 cm for rectum, and digitization errors >0.2 cm for prostate and >0.1 cm for urethra and rectum., Conclusions: A high variability in RPN scores was observed. Systematic simulations can provide insight in the severity scoring of multiple failure modes, supplementing typical FMEA approaches., Competing Interests: Conflict of Interest The authors do not have conflicts of interest related to this work to disclose., (Copyright © 2021 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To report early toxicity and tumor control outcomes of Pd-103 brachytherapy with ultrahypofractionated stereotactic radiation therapy (RT) for intermediate-risk prostate cancer., Methods and Materials: This prospective trial included 40 patients with intermediate-risk prostate cancer who underwent low-dose-rate (Pd-103) brachytherapy (prescription dose, 100 Gy), followed 1 month later with ultrahypofractionated stereotactic RT (25 Gy in 5 fractions) to the prostate and seminal vesicles. The primary endpoint was the rate of grade 2+ genitourinary toxicity at 12 months using Common Terminology Criteria for Adverse Events v 4.0. Secondary endpoints included patient-reported quality-of-life metrics (International Prostate Scoring System [IPSS], International Index of Erectile Function, and Expanded Prostate Cancer Index Composite-bowel). Biochemical failure was defined as prostate-specific antigen nadir +2 ng/mL. Posttreatment biopsies were performed at between 24 and 36 months; median follow-up was 36 months., Results: The rate of grade 2 urinary toxicity at 12 months was 25% with no grade 3 urinary toxicity noted. Mean IPSS at baseline and 12 and 24 months was 5, 10, and 6.2, respectively. Mean change in IPSS from baseline at 12 months was +5.5 (interquartile range, 1-9.75) and +1.05 (interquartile range, -3 to 3.25) at 24 months. Grade 2 bowel toxicity was 5% at 12 months with no grade 3 bowel toxicity noted. Mean Expanded Prostate Cancer Index Composite-bowel domain scores at baseline and 12 months were 92.8 and 90.3, respectively. Of patients who were potent (International Index of Erectile Function ≥21) at baseline, 75% remained potent at 12 months. Of 40 patients, 28 underwent posttreatment prostate biopsy (PPB), which was negative (n = 20) or demonstrated severe treatment effect (n = 8). No patient had a positive PPB or developed biochemical failure during the follow-up period. One patient without a PPB developed osseous metastases at 18 months posttreatment in the absence of biochemical failure., Conclusion: Low-dose-rate brachytherapy in combination with ultrahypofractionated stereotactic RT was safe and effective for intermediate-risk prostate cancer in early results of this trial., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose/objectives: Three-dimensional (3D) printing is recognized as an effective clinical and educational tool in procedurally intensive specialties. However, it has a nascent role in radiation oncology. The goal of this investigation is to clarify the extent to which 3D printing applications are currently being used in radiation oncology through a systematic review of the literature., Materials/methods: A search protocol was defined according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Included articles were evaluated using parameters of interest including: year and country of publication, experimental design, sample size for clinical studies, radiation oncology topic, reported outcomes, and implementation barriers or safety concerns., Results: One hundred and three publications from 2012 to 2019 met inclusion criteria. The most commonly described 3D printing applications included quality assurance phantoms (26%), brachytherapy applicators (20%), bolus (17%), preclinical animal irradiation (10%), compensators (7%), and immobilization devices (5%). Most studies were preclinical feasibility studies (63%), with few clinical investigations such as case reports or series (13%) or cohort studies (11%). The most common applications evaluated within clinical settings included brachytherapy applicators (44%) and bolus (28%). Sample sizes for clinical investigations were small (median 10, range 1-42). A minority of articles described basic or translational research (11%) and workflow or cost evaluation studies (3%). The number of articles increased over time (P < 0.0001). While outcomes were heterogeneous, most studies reported successful implementation of accurate and cost-effective 3D printing methods., Conclusions: Three-dimensional printing is rapidly growing in radiation oncology and has been implemented effectively in a diverse array of applications. Although the number of 3D printing publications has steadily risen, the majority of current reports are preclinical in nature and the few clinical studies that do exist report on small sample sizes. Further dissemination of ongoing investigations describing the clinical application of developed 3D printing technologies in larger cohorts is warranted., (© 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Purpose: To develop an Eclipse plug-in (MLC&#95;MODIFIER) that automatically modifies control points to expose fiducials obscured by MLC during VMAT, thereby facilitating tracking using periodic MV/kV imaging., Method: Three-dimensional fiducial tracking was performed during VMAT by pairing short-arc (3°) MV digital tomosynthesis (DTS) images to triggered kV images. To evaluate MLC&#95;MODIFIER efficacy, two cohorts of patients were considered. For first 12 patients, plans were manually edited to expose one fiducial marker. Next for 15 patients, plans were modified using MLC&#95;MODIFIER script. MLC&#95;MODIFIER evaluated MLC apertures at appropriate angles for marker visibility. Angles subtended by control points were compressed and low-dose "imaging" control points were inserted and exposed one marker with 1 cm margin. Patient's images were retrospectively reviewed to determine rate of MV registration failures. Failure categories were poor DTS image quality, MLC blockage of fiducials, or unknown reasons. Dosimetric differences in rectum, bladder, and urethra D1 cc, PTV maximum dose, and PTV dose homogeneity (PTV HI) were evaluated. Statistical significance was evaluated using Fisher's exact and Student's t test., Result: Overall MV registration failures, failures due to poor image quality, MLC blockage, and unknown reasons were 33% versus 8.9% (P < 0.0001), 8% versus 6.4% (P < 0.05), 13.6% versus 0.1% (P < 0.0001), and 7.6% versus 2.4% (P < 0.0001) for manually edited and MLC&#95;MODIFIER plans, respectively. PTV maximum and HI increased on average from unmodified plans by 2.1% and 0.3% (P < 0.004) and 22.0% and 3.3% (P < 0.004) for manually edited and MLC&#95;MODIFIED plans, respectively. Changes in bladder, rectum, and urethra D1CC were similar for each method and less than 0.7%., Conclusion: Increasing fiducial visibility via an automated process comprised of angular compression of control points and insertion of additional "imaging" control points is feasible. Degradation of plan quality is minimal. Fiducial detection and registration success rates are significantly improved compared to manually edited apertures., (© 2019 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)

Background: Intraoperative radiotherapy (IORT) is an effective strategy for the delivery of high doses of radiotherapy to a residual tumor or resection cavity with relative sparing of nearby healthy tissues. This strategy is an important component of the multimodality management of pediatric soft tissue sarcomas, particularly in cases where patients have received prior courses of external beam radiotherapy., Purpose: Tumor beds with significant topographic irregularity remain a therapeutic challenge because existing IORT technologies are typically most reliable with flat surfaces. To address this limitation, we have developed a novel strategy to create custom, prefabricated high-dose-rate (HDR)-IORT applicators designed to match the shape of an anticipated surgical cavity., Methods and Materials: Silastic applicators are constructed using three-dimensional (3D) printing and are derived from volumetric segmentation of preoperative imaging., Results: HDR preplanning with the applicators improves dosimetric accuracy and minimizes incremental operative time. In this report, we describe the fabrication process for the 3D-printed applicators and detail our experience utilizing this strategy in two pediatric patients who underwent HDR-IORT as part of complex base of skull sarcoma resections., Conclusions: Early experience suggests that usage of the custom applicators is feasible, versatile for a variety of clinical situations, and enables the uniform delivery of high superficial doses of radiotherapy to irregularly shaped surgical cavities., (Copyright © 2019 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: Rates of rectal toxicity after low-dose-rate (LDR) brachytherapy for prostate cancer are dependent on rectal dose, which is associated with rectal distance from prostate and implanted seeds. Placement of a hydrogel spacer between the prostate and rectum has proven to reduce the volume of the rectum exposed to higher radiation dose levels in the setting of external beam radiotherapy. We present our findings with placing a rectal hydrogel spacer in patients following LDR brachytherapy, and we further assess the impact of this placement on dosimetry and acute rectal toxicity., Methods and Materials: Between January 2016 and April 2017, 74 patients had placement of a hydrogel spacer, immediately following a Pd-103 seed-implant procedure. Brachytherapy was delivered as follows: as a monotherapy to 26 (35%) patients; as part of planned combination therapy with external beam radiotherapy to 40 (54%) patients; or as a salvage monotherapy to eight (11%) patients. Postoperative MRI was used to assess separation achieved with rectal spacer. Acute toxicity was assessed retrospectively using Radiation Oncology Therapy Group radiation toxicity grading system. Rectal dosimetry was compared with a consecutive cohort of 136 patients treated with seed implantation at our institution without a spacer, using a 2-tailed paired Student's t test (p < 0.05 for statistical significance)., Results: On average, 11.2-mm (SD 3.3) separation was achieved between the prostate and the rectum. The resultant mean rectal volume receiving 100% of prescribed dose (V 100% ), dose to 1 cc of rectum (D 1cc ), and dose to 2 cc of rectum (D 2cc ) were 0 (SD 0.05 cc), 25.3% (SD 12.7), and 20.5% (SD 9.9), respectively. All rectal dosimetric parameters improved significantly for the cohort with spacer placement as compared with the nonspacer cohort. Mean prostate volume, prostate V 100 and dose to 90% of gland (D 90 ) were 29.3 cc (SD 12.4), 94.0% (SD 3.81), and 112.4% (SD 12.0), respectively. Urethral D 20 , D 5cc , and D 1cc were 122.0% (SD 17.27), 133.8% (SD 22.8), and 144.0% (SD 25.4), respectively. After completing all treatments, at the time of first the followup, 7 patients reported acute rectal toxicity-6 experiencing Grade 1 rectal discomfort and 1 (with preexisting hemorrhoids) experiencing Grade 1 bleeding., Conclusions: Injection of rectal spacer is feasible in the post-LDR brachytherapy setting and reduces dose to the rectum with minimal toxicity. Prostate and urethral dosimetries do not appear to be affected by the placement of a spacer. Further studies with long-term followup are warranted to assess the impact on reduction of late rectal toxicity., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: Interstitial high-dose rate (HDR) brachytherapy is an important therapeutic strategy for the treatment of locally advanced gynecologic (GYN) cancers. The outcome of this therapy is determined by the quality of dose distribution achieved. This paper focuses on a novel yet simple heuristic for catheter selection for GYN HDR brachytherapy and their comparison against state of the art optimization strategies. The proposed technique is intended to act as a decision-supporting tool to select a favorable needle configuration., Materials: The presented heuristic for catheter optimization is based on a shrinkage-type algorithm (SACO). It is compared against state of the art planning in a retrospective study of 20 patients who previously received image-guided interstitial HDR brachytherapy using a Syed Neblett template. From those plans, template orientation and position are estimated via a rigid registration of the template with the actual catheter trajectories. All potential straight trajectories intersecting the contoured clinical target volume (CTV) are considered for catheter optimization. Retrospectively generated plans and clinical plans are compared with respect to dosimetric performance and optimization time., Results: All plans were generated with one single run of the optimizer lasting 0.6-97.4 s. Compared to manual optimization, SACO yields a statistically significant (P ≤ 0.05) improved target coverage while at the same time fulfilling all dosimetric constraints for organs at risk (OARs). Comparing inverse planning strategies, dosimetric evaluation for SACO and "hybrid inverse planning and optimization" (HIPO), as gold standard, shows no statistically significant difference (P > 0.05). However, SACO provides the potential to reduce the number of used catheters without compromising plan quality., Conclusion: The proposed heuristic for needle selection provides fast catheter selection with optimization times suited for intraoperative treatment planning. Compared to manual optimization, the proposed methodology results in fewer catheters without a clinically significant loss in plan quality. The proposed approach can be used as a decision support tool that guides the user to find the ideal number and configuration of catheters., (© 2017 American Association of Physicists in Medicine.)

Purpose: We designed and built dedicated active magnetic resonance (MR)-tracked (MRTR) stylets. We explored the role of MRTR in a prospective clinical trial., Methods and Materials: Eleven gynecologic cancer patients underwent MRTR to rapidly optimize interstitial catheter placement. MRTR catheter tip location and orientation were computed and overlaid on images displayed on in-room monitors at rates of 6 to 16 frames per second. Three modes of actively tracked navigation were analyzed: coarse navigation to the approximate region around the tumor; fine-tuning, bringing the stylets to the desired location; and pullback, with MRTR stylets rapidly withdrawn from within the catheters, providing catheter trajectories for radiation treatment planning (RTP). Catheters with conventional stylets were inserted, forming baseline locations. MRTR stylets were substituted, and catheter navigation was performed by a clinician working inside the MRI bore, using monitor feedback., Results: Coarse navigation allowed repositioning of the MRTR catheters tips by 16 mm (mean), relative to baseline, in 14 ± 5 s/catheter (mean ± standard deviation [SD]). The fine-tuning mode repositioned the catheter tips by a further 12 mm, in 24 ± 17 s/catheter. Pullback mode provided catheter trajectories with RTP point resolution of ∼1.5 mm, in 1 to 9 s/catheter., Conclusions: MRTR-based navigation resulted in rapid and optimal placement of interstitial brachytherapy catheters. Catheters were repositioned compared with the initial insertion without tracking. In pullback mode, catheter trajectories matched computed tomographic precision, enabling their use for RTP., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Purpose: To present the clinical commissioning of a novel 103 Pd directional brachytherapy device (CivaSheet) for intraoperative radiation therapy., Methods and Materials: Clinical commissioning for the CivaSheet consisted of establishing: (1) source strength calibration capabilities, (2) experimental verification of TG-43 dosimetry parameters, (3) treatment planning system validation, and (4) departmental practice for dose specification and source ordering. Experimental verification was performed in water with radiochromic film calibrated with a 37 kVp X-ray beam. Percentage difference ([measurements - calculation]/calculation) and distance to agreement (difference between film-to-source distance and distance that minimized the percentage difference) were calculated. Nomogram values (in U/100 Gy) for all configurations (up to 20 × 20 sources) were calculated for source ordering. Clinical commissioning was used on patients enrolled in an ongoing Institutional Review Board-approved protocol., Results: A source calibration procedure was established, and the treatment planning system was commissioned within standard clinical uncertainties. Percentage dose differences (distances to agreement) between measured and calculated doses were 8.6% (-0.12 mm), 0.6% (-0.01 mm), -6.4% (0.22 mm), and -10.0% (0.44 mm) at depths of 2.3, 5.1, 8.0, and 11.1 mm, respectively. All differences were within the experimental uncertainties. Nomogram values depended on sheet size and spatial extent. A value of 2.4U/100 Gy per CivaDot was found to satisfy most cases, ranging from 2.3 to 3.3U/100 Gy. Nomogram results depended on elongation of the treatment area with a higher variation observed for smaller treatment areas. Postimplantation dose evaluation was feasible., Conclusions: Commissioning and clinical deployment of CivaSheet was feasible using BrachyVision for postoperative dose evaluation. Experimental verification confirmed that the available TG-43 dosimetry parameters are accurate for clinical use., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare clinical outcomes of MR-based versus CT-based high-dose-rate interstitial brachytherapy (ISBT) for vaginal recurrence of endometrioid endometrial cancer (EC)., Methods and Materials: We reviewed 66 patients with vaginal recurrent EC; 18 had MR-based ISBT on a prospective clinical trial and 48 had CT-based treatment. Kaplan-Meier survival modeling was used to generate estimates for local control (LC), disease-free interval (DFI), and overall survival (OS), and multivariate Cox modeling was used to assess prognostic factors. Toxicities were evaluated and compared., Results: Median followup was 33 months (CT 30 months, MR 35 months). Median cumulative equivalent dose in 2-Gy fractions was 75.5 Gy for MR-ISBT and 73.8 Gy for CT-ISBT (p = 0.58). MR patients were older (p = 0.03) and had larger tumor size (>4 cm vs. ≤ 4 cm) compared to CT patients (p = 0.04). For MR-based versus CT-based ISBT, 3-year KM rate for local control was 100% versus 78% (p = 0.04), DFI was 69% versus 55% (p = 0.1), and OS was 63% versus 75% (p = 0.81), respectively. On multivariate analysis, tumor Grade 3 was associated with worse OS (HR 3.57, 95% CI 1.25, 11.36) in a model with MR-ISBT (HR 0.56, 95% CI 0.16, 1.89). Toxicities were not significantly different between the two modalities., Conclusion: Despite worse patient prognostic features, MR-ISBT was associated with a significantly better (100%) 3-year local control, comparable survival, and improved DFI rates compared to CT. Toxicities did not differ compared to CT-ISBT patients. Tumor grade contributed as the most significant predictor for survival. Larger prospective studies are needed to assess the impact of MR-ISBT on survival outcomes., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: In this study, we introduce a novel, fast, inverse treatment planning strategy for interstitial high-dose-rate (HDR) brachytherapy with multiple regions of interest solely based on dose-volume-histogram-related dosimetric measures (DMs)., Methods: We present a new problem formulation of the objective function that approximates the indicator variables of the standard DM optimization problem with a smooth logistic function. This problem is optimized by standard gradient-based methods. The proposed approach is then compared against state-of-the-art optimization strategies., Results: All generated plans fulfilled prescribed DMs for all organs at risk. Compared to clinical practice, a statistically significant improvement (p=0.01) in coverage of target structures was achieved. Simultaneously, DMs representing high-dose regions were significantly reduced (p=0.01). The novel optimization strategies run-time was (0.8 ± 0.3) s and thus outperformed the best competing strategies of the state of the art. In addition, the novel DM-based approach was associated with a statistically significant (p=0.01) increase in the number of active dwell positions and a decrease in the maximum dwell time., Conclusions: The generated plans showed a clinically significant increase in target coverage with fewer hot spots, with an optimization time approximately three orders of magnitude shorter than manual optimization currently used in clinical practice. As optimization is solely based on DMs, intuitive, interactive, real-time treatment planning, which motivated the adoption of manual optimization in our clinic, is possible., (© 2017 American Association of Physicists in Medicine.)

Purpose: The aim of this study was to evaluate injection of a novel hydrogel (TraceIT; Augmenix, Waltham, MA) between the cervix, rectum, and bladder in female cadavers compared with, and in addition to, the current standard of gauze packing, for organ-at-risk sparing in cervical cancer brachytherapy planning., Methods and Materials: This brachytherapy cadaver study used T2-weighted MRI and CT imaging to compare three scenarios: (1) gauze packing alone, (2) hydrogel injection placed in the cervical fornices and rectovaginal septum, and (3) gauze packing in conjunction with hydrogel injection. Hydrogel distribution was evaluated. Doses to 2 cm 3 volumes (D 2cc ) for the rectum, bladder, and sigmoid were collected. Statistical significance (p < 0.05) was evaluated using a two-tailed paired t test., Results: Hydrogel was successfully injected to space the bladder and rectum from the cervix in all five cadavers. The spacer was easily identifiable on both CT and MRI. The use of hydrogel in addition to packing resulted in a 22% decrease in rectum D 2cc dose (p = 0.02), a 10% decrease in bladder D 2cc (p = 0.27), and no change in sigmoid D 2cc dose. No difference was observed between hydrogel only vs. gauze packing only., Conclusions: Our results revealed a significant clinically meaningful decrease in rectal D 2cc associated with the use of hydrogel in addition to gauze packing-TraceIT hydrogel holds promise as a spacer in cervical cancer therapy., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Magnetic resonance imaging (MRI) is increasingly being used in radiation therapy, and integration of MRI into brachytherapy in particular is becoming more common. We present here a systematic review of the basic physics and technical aspects of incorporating MRI into prostate brachytherapy. Terminology and MRI system components are reviewed along with typical work flows in prostate high-dose-rate and low-dose-rate brachytherapy. In general, the brachytherapy workflow consists of five key components: diagnosis, implantation, treatment planning (scan + plan), implant verification, and delivery. MRI integration is discussed for diagnosis; treatment planning; and MRI-guided brachytherapy implants, in which MRI is used to guide the physical insertion of the brachytherapy applicator or needles. Considerations and challenges for establishing an MRI brachytherapy program are also discussed., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To investigate the dose-volume histogram metrics and optimization results of the contoured bowel in cervical cancer brachytherapy., Methods and Materials: Treatment plans of cervical cancer patients treated with image-guided high dose rate were retrospectively analyzed with institutional review board approval. In addition to the clinical target volume, rectum, bladder, and sigmoid, the bowel was contoured at the time of planning (Group 1) or at the time of this analysis (Group 2)., Results: Thirty-two patients treated with 145 insertions were included. Before optimization, mean ± 1 standard deviation overall bowel minimum dose to the most irradiated 2 cm 3 volume of an organ (D 2cc ) was 67.8 Gy α/β3 ± 13.7 Gy α/β3 (Group 1: 72.6 ± 13.2 Gy α/β3 ; Group 2: 57.3 ± 8.0 Gy α/β3 ). Before optimization, one patient in Group 1 presented a bowel D 2cc metric exceeding 100 Gy α/β3 . After optimization, bowel D 2cc mean ± 1 standard deviation was 59.4 ± 6.7 Gy α/β3 (Group 1: 61.4 ± 6.0 Gy α/β3 , p < 0.001; Group 2: 55.2 ± 6.5 Gy α/β3 , p = 0.026)., Conclusions: Given the potentially high doses and the benefit of optimization in reducing dose to the organs at risk, we recommend consideration of systematic contouring of the bowel when bowel is present in the pelvis., (Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose was to compare local control (LC), overall survival (OS) and dose to the organs at risk (OAR) in women with locally advanced cervical cancer treated with MR-guided versus CT-guided interstitial brachytherapy (BT)., Methods: 56 patients (29 MR, 27 CT) were treated with high-dose-rate (HDR) interstitial BT between 2005-2015. The MR patients had been prospectively enrolled on a Phase II clinical trial. Data were analyzed using Kaplan-Meier (K-M) and Cox proportional hazards statistical modeling in JMP® & R®., Results: Median follow-up time was 19.7months (MR group) and 18.4months (CT group). There were no statistically significant differences in patient age at diagnosis, histology, percent with tumor size >4cm, grade, FIGO stage or lymph node involvement between the groups. Patients in the MR group had more lymphovascular involvement compared to patients in the CT group (p<0.01). When evaluating plans generated, there were no statistically significant differences in median cumulative dose to the high-risk clinical target volume or the OAR. 2-year K-M LC rates for MR-based and CT-based treatments were 96% and 87%, respectively (log-rank p=0.65). At 2years, OS was significantly better in the MR-guided cohort (84% vs. 56%, p=0.036). On multivariate analysis, squamous histology was associated with longer OS (HR 0.23, 95% CI 0.07-0.72) in a model with MR BT (HR 0.35, 95% CI 0.08-1.18). There was no difference in toxicities between CT and MR BT., Conclusion: In this population of locally advanced cervical-cancer patients, MR-guided HDR BT resulted in estimated 96% 2-year local control and excellent survival and toxicity rates., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The purpose of this study was to investigate class solutions using RapidArc volumetric-modulated arc therapy (VMAT) planning for ipsilateral and bilateral head and neck (H&N) irradiation, and to compare dosimetric results with intensity-modulated radiotherapy (IMRT) plans. A total of 14 patients who received ipsilateral and 10 patients who received bilateral head and neck irradiation were retrospectively replanned with several volumetric-modulated arc therapy techniques. For ipsilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the contralateral parotid, two 260° or 270° arcs, and two 210° arcs. For bilateral neck irradiation, the volumetric-modulated arc therapy techniques included two 360° arcs, two 360° arcs with avoidance sectors around the shoulders, and 3 arcs. All patients had a sliding-window-delivery intensity-modulated radiotherapy plan that was used as the benchmark for dosimetric comparison. For ipsilateral neck irradiation, a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid was dosimetrically comparable to intensity-modulated radiotherapy, with improved conformity (conformity index = 1.22 vs 1.36, p < 0.04) and lower contralateral parotid mean dose (5.6 vs 6.8Gy, p < 0.03). For bilateral neck irradiation, 3-arc volumetric-modulated arc therapy techniques were dosimetrically comparable to intensity-modulated radiotherapy while also avoiding irradiation through the shoulders. All volumetric-modulated arc therapy techniques required fewer monitor units than sliding-window intensity-modulated radiotherapy to deliver treatment, with an average reduction of 35% for ipsilateral plans and 67% for bilateral plans. Thus, for ipsilateral head and neck irradiation a volumetric-modulated arc therapy technique using two 360° arcs with avoidance sectors around the contralateral parotid is recommended. For bilateral neck irradiation, 2- or 3-arc techniques are dosimetrically comparable to intensity-modulated radiotherapy, but more work is needed to determine the optimal approaches by disease site., (Copyright © 2017 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.)

Purpose: Advanced imaging used in combination with brachytherapy (BT) has revolutionized the treatment of patients with cervical cancer. We present a comprehensive review of the literature for definitive radiation with high-dose-rate (HDR) BT. In addition, we investigate potential outcome improvement with image-based brachytherapy (IBBT) compared to studies using traditional Point A dosing. This review extensively investigates acute and late toxicities., Methods and Materials: This study reviews the literature from 2000 to 2015 with an emphasis on modern approaches including concurrent chemotherapy (chemoRT), radiation, and HDR BT and IBBT. Descriptive statistics and pelvic control (PC), disease-free survival (DFS), and overall survival (OS) outcomes were calculated using weighted means to report pooled analysis of outcomes., Results: Literature search yielded 16 prospective, 51 retrospective studies that reported survival outcomes, and 13 retrospective studies that focused on acute and late toxicity outcomes regardless of applicator type. There are 57 studies that report Point A dose specification with 33 having chemoRT, and 10 studies that use IBBT, 8 with chemoRT. Patients receiving radiation and chemoRT with HDR BT in the prospective studies, with >24 months followup, rates of PC were: for RT: 73%, SD: 11; CRT: 82%, SD: 8; DFS-RT: 55%, SD: 10; CRT: 65%, SD: 7; OS-RT: 66%, SD: 7; CRT: 70%, SD: 11. In the retrospective studies, the PC rates (weighted means) for the radiation and chemoradiation outcomes are 75% vs. 80%, and for DFS, the values were 55% vs. 63%, respectively. Comparing patients receiving chemoRT and IBBT to traditional Point A dose specification, there is a significant improvement in PC (p < 0.01) and DFS (p < 0.01) with IBBT. The range of genitourinary late toxicity reported for radiation was Grade 3: 1-6% and for chemoRT 2-20%. The range of late gastrointestinal toxicity for radiation was Grade 3: 4-11% and for chemoRT, 1-11%. For the late gynecologic toxicity, only 1 of the 16 prospective trials report a Grade 1-2 of 17% for radiation and 9% for chemoRT effects., Conclusions: We present concise outcomes of PC, DFS, OS, and toxicity for cervical cancer patients treated with chemoradiation and HDR BT. Our data suggest an improvement in outcomes with the use of IBBT compared with traditional Point A dose prescriptions. In conclusion, HDR BT is a safe, effective modality when combined with IBBT., (Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Objective: To determine prognostic factors for progression-free survival (PFS) and overall survival (OS) for stage I-II cervical-cancer patients treated using computed-tomography (CT)-planned high-dose-rate (HDR) intracavitary brachytherapy (BT)., Methods: A total of 150 patients were treated for Stage I-II cervical cancer using CT-planned BT between 4/2004 and 10/2014. Of these, 128 were eligible for inclusion. Kaplan-Meier local control (LC), pelvic control (PC), overall survival (OS), and PFS estimates were calculated., Results: After a median follow-up of 30months, the 2-year LC rate was 96%, PFS was 88%, and OS was 88%. Overall, 18 patients (14%) experienced any recurrence (AR), 8 had distant recurrence only and 10 had a combination of local, pelvic, regional, and distant recurrence. No patients had LR only. A prognostic factor for AR was tumor size >4cm (p=0.01). Patients with tumors >4cm were 3.3 times more likely to have AR than those with tumors ≤4cm (hazard ratio [HR]=3.3; 95% confidence interval [CI] 1.28-9.47). Point A was 85% of prescription for tumors < 4 cm and decreased approximately 3% over 5 fractions compared to 90% of prescription for tumors > 4 cm that decreased approximately 4% over 5 fractions. Two patients (2%) experienced grade≥2 late toxicity. There were no acute or late grade≥3 toxicities., Conclusion: CT-planned BT resulted in excellent local control and survival. Large tumor size was associated with an increased risk of recurrence outside the radiation field and worse PFS and OS. A volume-optimized plan treated a smaller area than a point A standard plan for patients with Stage I-II cervical cancer that have received chemoradiation. Given the outstanding LC achieved with modern therapy including chemoradiation, HDR, and image-based BT, further efforts to combat spread outside the radiation field with novel therapies are warranted., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: To assess whether R2* mapping with a standard Monoexponential (ME) or a Gaussian Augmentation of the Monoexponential (GAME) decay model better characterizes gradient-echo signal decays in gynecological cancers after external beam radiation therapy at 3T, and evaluate implications of modeling for noninvasive identification of intratumoral hypoxia., Materials and Methods: Multi-gradient-echo signals were acquired on 25 consecutive patients with gynecologic cancers and three healthy participants during inhalation of different oxygen concentrations at 3T. Data were fitted with both ME and GAME models. Models were compared using F-tests in tumors and muscles in patients, muscles, cervix, and uterus in healthy participants, and across oxygenation levels., Results: GAME significantly improved fitting over ME (P < 0.05): Improvements with GAME covered 34% of tumor regions-of-interest on average, ranging from 6% (of a vaginal tumor) to 68% (of a cervical tumor) in individual tumors. Improvements with GAME were more prominent in areas that would be assumed hypoxic based on ME alone, reaching 90% as ME R2* approached 100 Hz. Gradient echo decay parameters at different oxygenation levels were not significantly different (P = 0.81)., Conclusion: R2* may prove sensitive to hypoxia; however, inaccurate representations of underlying data may limit the success of quantitative assessments. Although the degree to which R2 or σ values correlate with hypoxia remains unknown, improved characterization with GAME increases the potential for determining any correlates of fit parameters with biomarkers, such as oxygenation status. J. MAGN. RESON. IMAGING 2016;44:1020-1030., (© 2016 International Society for Magnetic Resonance in Medicine.)

Purpose: To compare clinical outcomes of image-based versus non-image-based interstitial brachytherapy (IBBT) for vaginal cancer., Methods and Materials: Of 72 patients with vaginal cancer treated with brachytherapy (BT), 47 had image guidance (CT=31, MRI=16) and 25 did not. Kaplan-Meier (KM) estimates were generated for any recurrence, local control (LC), disease-free interval (DFI), and overall survival (OS) and Cox models were used to assess prognostic factors., Results: Median age was 66 and median follow-up time was 24months. Median cumulative EQD2 dose was 80.8Gy in the non-IBBT group and 77Gy in the IBBT group. For non-IBBT versus IBBT, the 2-year KM LC was 71% vs. 93% (p=0.03); DFI was 54% vs. 86% (p=0.04); and OS 52% vs. 82% (p=0.35). On multivariate analysis, IBBT was associated with better DFI (HR 0.24, 95% CI 0.07-0.73). Having any 2 or more of chemotherapy, high-dose-rate (HDR) BT or IBBT (temporally correlated variables) significantly reduced risk of relapse (HR=0.33, 95% CI=0.13-0.83), compared to having none of these factors., Conclusion: Over time, the use of chemotherapy, HDR, and IBBT has increased in vaginal cancer. The combination of these factors resulted in the highest rates of disease control. Image-guided brachytherapy for vaginal cancer patients maximizes disease control., Competing Interests: Statement All authors declare that they have no conflicts of interest., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Purpose: There is a lack of prescriptive, practical information for those doing the work of commissioning high-dose-rate (HDR) gynecologic (GYN) treatment equipment. The purpose of this work is to develop a vendor-neutral, consensus-based, commissioning template to improve standardization of the commissioning process., Methods and Materials: A series of commissioning procedures and tests specific to HDR GYN treatments were compiled within one institution. The list of procedures and tests was then sent to five external reviewers at clinics engaged in HDR GYN treatments. External reviewers were asked to (1) suggest deletions, additions, and improvements/modifications to descriptions, (2) link the procedures and tests to common, severe failure modes based on their effectiveness at mitigating those failure modes, and (3) rank the procedures and tests based on perceived level of importance., Results: External reviewers suggested the addition of 14 procedures and tests. The final template consists of 67 procedures and tests. "Treatment process" and "staff training" sections were identified as mitigating the highest number of commonly reported failure modes. The mean perceived importance for all procedures and tests was 4.4 of 5, and the mean for each section ranged from 3.6 to 4.8. Sections of the template that were identified as mitigating the highest number of commonly reported failure modes were not assigned the highest perceived importance., Conclusion: The commissioning template developed here provides a standardized approach to process and equipment commissioning. The discord between perceived importance and mitigation of the highest number of failure modes suggests that increased focus should be placed on procedures and tests in "treatment process" and "staff training" sections., (Copyright © 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: In this study, we present the clinical implementation of a novel transoral balloon centering esophageal applicator (BCEA) and the initial clinical experience in high-dose-rate (HDR) brachytherapy treatment of esophageal cancer, using this applicator., Material and Methods: Acceptance testing and commissioning of the BCEA were performed prior to clinical use. Full performance testing was conducted including measurements of the dimensions and the catheter diameter, evaluation of the inflatable balloon consistency, visibility of the radio-opaque markers, congruence of the markers, absolute and relative accuracy of the HDR source in the applicator using the radiochromic film and source position simulator, visibility and digitization of the applicator on the computed tomography (CT) images under the clinical conditions, and reproducibility of the offset. Clinical placement of the applicator, treatment planning, treatment delivery, and patient's response to the treatment were elaborated as well., Results: The experiments showed sub-millimeter accuracy in the source positioning with distal position at 1270 mm. The digitization (catheter reconstruction) was uncomplicated due to the good visibility of markers. The treatment planning resulted in a favorable dose distribution. This finding was pronounced for the treatment of the curvy anatomy of the lesion due to the improved repeatability and consistency of the delivered fractional dose to the patient, since the radioactive source was placed centrally within the lumen with respect to the clinical target due to the five inflatable balloons., Conclusions: The consistency of the BCEA positioning resulted in the possibility to deliver optimized non-uniform dose along the catheter, which resulted in an increase of the dose to the cancerous tissue and lower doses to healthy tissue. A larger number of patients and long-term follow-up will be required to investigate if the delivered optimized treatment can lead to improved clinical outcomes.

Objective: Lower extremity lymphedema adversely affects quality of life by causing discomfort, impaired mobility and increased risk of infection. The goal of this study is to investigate factors that influence the likelihood of lymphedema in patients with endometrial cancer who undergo adjuvant radiation with or without chemotherapy., Methods: A retrospective chart review identified all stage I-III endometrial cancer patients who had a hysterectomy with or without complete staging lymphadenectomy and adjuvant radiation therapy between January 2006 and February 2013. Patients with new-onset lymphedema after treatment were identified. Logistic regression was used to find factors that influenced lymphedema risk., Results: Of 212 patients who met inclusion criteria, 15 patients (7.1%) developed new-onset lymphedema. Lymphedema was associated with lymph-node dissection (odds ratio [OR], 5.6; 95% CI, 1.01 to 105.5; p=0.048) and with the presence of pathologically positive lymph nodes (OR, 4.1; 95% CI, 1.4 to 12.3; p=0.01). Multivariate logistic regression confirmed the association with lymph-node positivity (OR, 3.2; 95% CI, 1.0007 to 10.7; p=0.0499) when controlled for lymph-node dissection. Median time to lymphedema onset was 8 months (range, 1 to 58 months) with resolution or improvement in eight patients (53.3%) after a median of 10 months., Conclusion: Lymph-node positivity was associated with an increased risk of lymphedema in endometrial cancer patients who received adjuvant radiation. Future studies are needed to explore whether node-positive patients may benefit from early lymphedema-controlling interventions.

Purpose: In gynecologic cancers, magnetic resonance (MR) imaging is the modality of choice for visualizing tumors and their surroundings because of superior soft-tissue contrast. Real-time MR guidance of catheter placement in interstitial brachytherapy facilitates target coverage, and would be further improved by providing intraprocedural estimates of dosimetric coverage. A major obstacle to intraprocedural dosimetry is the time needed for catheter trajectory reconstruction. Herein the authors evaluate an active MR tracking (MRTR) system which provides rapid catheter tip localization and trajectory reconstruction. The authors assess the reliability and spatial accuracy of the MRTR system in comparison to standard catheter digitization using magnetic resonance imaging (MRI) and CT., Methods: The MRTR system includes a stylet with microcoils mounted on its shaft, which can be inserted into brachytherapy catheters and tracked by a dedicated MRTR sequence. Catheter tip localization errors of the MRTR system and their dependence on catheter locations and orientation inside the MR scanner were quantified with a water phantom. The distances between the tracked tip positions of the MRTR stylet and the predefined ground-truth tip positions were calculated for measurements performed at seven locations and with nine orientations. To evaluate catheter trajectory reconstruction, fifteen brachytherapy catheters were placed into a gel phantom with an embedded catheter fixation framework, with parallel or crossed paths. The MRTR stylet was then inserted sequentially into each catheter. During the removal of the MRTR stylet from within each catheter, a MRTR measurement was performed at 40 Hz to acquire the instantaneous stylet tip position, resulting in a series of three-dimensional (3D) positions along the catheter's trajectory. A 3D polynomial curve was fit to the tracked positions for each catheter, and equally spaced dwell points were then generated along the curve. High-resolution 3D MRI of the phantom was performed followed by catheter digitization based on the catheter's imaging artifacts. The catheter trajectory error was characterized in terms of the mean distance between corresponding dwell points in MRTR-generated catheter trajectory and MRI-based catheter digitization. The MRTR-based catheter trajectory reconstruction process was also performed on three gynecologic cancer patients, and then compared with catheter digitization based on MRI and CT., Results: The catheter tip localization error increased as the MRTR stylet moved further off-center and as the stylet's orientation deviated from the main magnetic field direction. Fifteen catheters' trajectories were reconstructed by MRTR. Compared with MRI-based digitization, the mean 3D error of MRTR-generated trajectories was 1.5 ± 0.5 mm with an in-plane error of 0.7 ± 0.2 mm and a tip error of 1.7 ± 0.5 mm. MRTR resolved ambiguity in catheter assignment due to crossed catheter paths, which is a common problem in image-based catheter digitization. In the patient studies, the MRTR-generated catheter trajectory was consistent with digitization based on both MRI and CT., Conclusions: The MRTR system provides accurate catheter tip localization and trajectory reconstruction in the MR environment. Relative to the image-based methods, it improves the speed, safety, and reliability of the catheter trajectory reconstruction in interstitial brachytherapy. MRTR may enable in-procedural dosimetric evaluation of implant target coverage.

Gynecologic brachytherapy consists of positioning radioactive sources in catheters implanted inside a tumor. MR imaging provides tumor visibility and is ideal for image-guided insertions and treatment planning. It is important at first insertion and during treatment of large residual tumors potentially needing interstitial needles. Clear visibility of the tumor and the catheters is necessary for MR-guided brachytherapy. T2 sequences are ideal for tumor visibility but catheter visualization may be difficult. Active tracking and alternative sequences to improve catheter visibility have been explored. The use of digital applicator models, dummy markers, and CT-MR fusion is reviewed., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Purpose: To increase intraprocedural efficiency in the use of clinical resources and to decrease planning time for cervical cancer brachytherapy treatments through redesign of the procedure's process map., Methods and Materials: A multidisciplinary team identified all tasks and associated resources involved in cervical cancer brachytherapy in our institution and arranged them in a process map. A redesign of the treatment planning component of the process map was conducted with the goal of minimizing planning time. Planning time was measured on 20 consecutive insertions, of which 10 were performed with standard procedures and 10 with the redesigned process map, and results were compared. Statistical significance (p < 0.05) was measured with a two-tailed t test., Results: Twelve tasks involved in cervical cancer brachytherapy treatments were identified. The process map showed that in standard procedures, the treatment planning tasks were performed sequentially. The process map was redesigned to specify that contouring and some planning tasks are performed concomitantly. Some quality assurance tasks were reorganized to minimize adverse effects of a possible error on procedure time. Test dry runs followed by live implementation confirmed the applicability of the new process map to clinical conditions. A 29% reduction in planning time (p < 0.01) was observed with the introduction of the redesigned process map., Conclusions: A process map for cervical cancer brachytherapy was generated. The treatment planning component of the process map was redesigned, resulting in a 29% decrease in planning time and a streamlining of the quality assurance process., (Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To develop an active MR-tracking system to guide placement of metallic devices for radiation therapy., Methods: An actively tracked metallic stylet for brachytherapy was constructed by adding printed-circuit micro-coils to a commercial stylet. The coil design was optimized by electromagnetic simulation, and has a radio-frequency lobe pattern extending ∼5 mm beyond the strong B0 inhomogeneity region near the metal surface. An MR-tracking sequence with phase-field dithering was used to overcome residual effects of B0 and B1 inhomogeneities caused by the metal, as well as from inductive coupling to surrounding metallic stylets. The tracking system was integrated with a graphical workstation for real-time visualization. The 3 Tesla MRI catheter-insertion procedures were tested in phantoms and ex vivo animal tissue, and then performed in three patients during interstitial brachytherapy., Results: The tracking system provided high-resolution (0.6 × 0.6 × 0.6 mm(3) ) and rapid (16 to 40 frames per second, with three to one phase-field dithering directions) catheter localization in phantoms, animals, and three gynecologic cancer patients., Conclusion: This is the first demonstration of active tracking of the shaft of metallic stylet in MR-guided brachytherapy. It holds the promise of assisting physicians to achieve better targeting and improving outcomes in interstitial brachytherapy., (© 2014 Wiley Periodicals, Inc.)

Purpose: To investigate the dose distributions associated with a novel balloon sleeve placed over a standard cylinder applicator., Material and Methods: A computed tomography (CT) scan of a sleeve balloon shaped to inflate into the vaginal fornices was used to digitize 1-, 3-, and 5-catheter configurations. Point doses for rectum, apex, and fornix were calculated and compared to the values associated with a standard cylinder plan not targeting the vaginal fornices. Inflation of the sleeve balloon in the vaginal fornices and dose coverage with constraints to the rectum, bladder, and sigmoid D2cc were evaluated., Results: Rectum, apex, and fornix doses were respectively 76%, 119%, and 44% for a standard cylinder; 190%, 310%, and 93% for a 1-catheter configuration; 98%, 109%, and 109% for a 3-catheter configuration; and 91%, 107%, and 96% for the 5-catheter configuration. In a patient analysis, expansion of the sleeve balloon into the vaginal fornices was confirmed. The 5-catheter configurations were associated with best coverage of the fornices and acceptable doses to rectum, bladder, and sigmoid., Conclusions: A 1-catheter configuration cannot be used clinically due to high rectal and apex dose. In theoretical analysis, the 3- and 5-catheter configurations showed > 96% coverage to the vaginal fornices with a clinically acceptable rectal dose. In a treatment simulation in a patient, a 5-catheter configuration showed 90% coverage of the fornices with acceptable doses to the organs at risk. The treatment of deep vaginal fornices results in an increased rectal dose compared to a standard cylinder plan.

Background and Purpose: To compare the pre-treatment brachytherapy plan verification by a physicist assisted by custom plan verification software (SAV) with those performed manually (MV)., Materials and Methods: All HDR brachytherapy plans used for treatment in 2013, verified using either SAV or MV, were retrospectively reviewed. Error rate (number of errors/number of plans) was measured and verification time calculated. All HDR brachytherapy safety events recorded between 2010 and 2013 were identified. The rate of patient-related safety events (number of events/number of fractions treated) and the impact of SAV on the underlying errors were assessed., Results: Three/106 errors (2.8%) were found in the SAV group and 24/273 (8.8%) in the MV group (p=0.046). The mean ±1 standard deviation plan verification time was 8.4±4.0min for SAV and 11.6±5.3 for MV (p=0.006). Seven safety events out of 4729 fractions delivered (0.15%) were identified. Four events (57%) were associated with plan verification and could have been detected by SAV., Conclusions: We found a safety event rate in HDR brachytherapy of 0.15%. SAV significantly reduced the number of undetected errors in HDR treatment plans compared to MV, and reduced the time required for plan verification., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Purpose: To investigate the use of a system using electromagnetic tracking (EMT), post-processing and an error-detection algorithm for detecting errors and resolving uncertainties in high-dose-rate brachytherapy catheter digitization for treatment planning., Methods: EMT was used to localize 15 catheters inserted into a phantom using a stepwise acquisition technique. Five distinct acquisition experiments were performed. Noise associated with the acquisition was calculated. The dwell location configuration was extracted from the EMT data. A CT scan of the phantom was performed, and five distinct catheter digitization sessions were performed. No a priori registration of the CT scan coordinate system with the EMT coordinate system was performed. CT-based digitization was automatically extracted from the brachytherapy plan DICOM files (CT), and rigid registration was performed between EMT and CT dwell positions. EMT registration error was characterized in terms of the mean and maximum distance between corresponding EMT and CT dwell positions per catheter. An algorithm for error detection and identification was presented. Three types of errors were systematically simulated: swap of two catheter numbers, partial swap of catheter number identification for parts of the catheters (mix), and catheter-tip shift. Error-detection sensitivity (number of simulated scenarios correctly identified as containing an error/number of simulated scenarios containing an error) and specificity (number of scenarios correctly identified as not containing errors/number of correct scenarios) were calculated. Catheter identification sensitivity (number of catheters correctly identified as erroneous across all scenarios/number of erroneous catheters across all scenarios) and specificity (number of catheters correctly identified as correct across all scenarios/number of correct catheters across all scenarios) were calculated. The mean detected and identified shift was calculated., Results: The maximum noise ±1 standard deviation associated with the EMT acquisitions was 1.0 ± 0.1 mm, and the mean noise was 0.6 ± 0.1 mm. Registration of all the EMT and CT dwell positions was associated with a mean catheter error of 0.6 ± 0.2 mm, a maximum catheter error of 0.9 ± 0.4 mm, a mean dwell error of 1.0 ± 0.3 mm, and a maximum dwell error of 1.3 ± 0.7 mm. Error detection and catheter identification sensitivity and specificity of 100% were observed for swap, mix and shift (≥2.6 mm for error detection; ≥2.7 mm for catheter identification) errors. A mean detected shift of 1.8 ± 0.4 mm and a mean identified shift of 1.9 ± 0.4 mm were observed., Conclusions: Registration of the EMT dwell positions to the CT dwell positions was possible with a residual mean error per catheter of 0.6 ± 0.2 mm and a maximum error for any dwell of 1.3 ± 0.7 mm. These low residual registration errors show that quality assurance of the general characteristics of the catheters and of possible errors affecting one specific dwell position is possible. The sensitivity and specificity of the catheter digitization verification algorithm was 100% for swap and mix errors and for shifts ≥2.6 mm. On average, shifts ≥1.8 mm were detected, and shifts ≥1.9 mm were detected and identified.

Background: Prostate volume can affect whether patients qualify for brachytherapy (desired size ≥20 mL and ≤60 mL) and/or active surveillance (desired PSA density ≤0.15 for very low risk disease). This study examines variability in prostate volume measurements depending on imaging modality used (ultrasound versus MRI) and volume calculation technique (contouring versus ellipsoid) and quantifies the impact of this variability on treatment recommendations for men with favorable-risk prostate cancer., Methods: We examined 70 patients who presented consecutively for consideration of brachytherapy for favorable-risk prostate cancer who had volume estimates by three methods: contoured axial ultrasound slices, ultrasound ellipsoid (height × width × length × 0.523) calculation, and endorectal coil MRI (erMRI) ellipsoid calculation., Results: Average gland size by the contoured ultrasound, ellipsoid ultrasound, and erMRI methods were 33.99, 37.16, and 39.62 mLs, respectively. All pairwise comparisons between methods were statistically significant (all p < 0.015). Of the 66 patients who volumetrically qualified for brachytherapy on ellipsoid ultrasound measures, 22 (33.33%) did not qualify on ellipsoid erMRI or contoured ultrasound measures. 38 patients (54.28%) had PSA density ≤0.15 ng/dl as calculated using ellipsoid ultrasound volumes, compared to 34 (48.57%) and 38 patients (54.28%) using contoured ultrasound and ellipsoid erMRI volumes, respectively., Conclusions: The ultrasound ellipsoid and erMRI ellipsoid methods appeared to overestimate ultrasound contoured volume by an average of 9.34% and 16.57% respectively. 33.33% of those who qualified for brachytherapy based on ellipsoid ultrasound volume would be disqualified based on ultrasound contoured and/or erMRI ellipsoid volume. As treatment recommendations increasingly rely on estimates of prostate size, clinicians must consider method of volume estimation.

Purpose: To investigate the dosimetric variability associated with interobserver organ-at-risk delineation differences on computed tomography in patients undergoing gynecologic interstitial brachytherapy., Methods and Materials: The rectum, bladder, and sigmoid of 14 patients treated with gynecologic interstitial brachytherapy were retrospectively contoured by 13 physicians. Geometric variability was calculated using κ statistics, conformity index (CIgen), and coefficient of variation (CV) of volumes contoured across physicians. Dosimetric variability of the single-fraction D0.1cc and D2cc was assessed through CV across physicians, and the standard deviation of the total EQD2 (equivalent dose in 2 Gy per fraction) brachytherapy dose (SD(TOT)) was calculated., Results: The population mean ± 1 standard deviation of κ, CIgen, and volume CV were, respectively: 0.77 ± 0.06, 0.70 ± 0.08, and 20% ± 6% for bladder; 0.74 ± 06, 0.67 ± 0.08, and 20% ± 5% for rectum; and 0.33 ± 0.20, 0.26 ± 0.17, and 82% ± 42% for sigmoid. Dosimetric variability was as follows: for bladder, CV = 31% ± 19% (SD(TOT) = 72 ± 64 Gy) for D0.1cc and CV = 16% ± 10% (SD(TOT) = 9 ± 6 Gy) for D2cc; for rectum, CV = 11% ± 5% (SD(TOT) = 16 ± 17 Gy) for D0.1cc and CV = 7% ± 2% (SD(TOT) = 4 ± 3 Gy) for D2cc; for sigmoid, CV = 39% ± 28% (SD(TOT) = 12 ± 18 Gy) for D0.1cc and CV = 34% ± 19% (SD(TOT) = 4 ± 4 Gy) for D2cc., Conclusions: Delineation of bladder and rectum by 13 physicians demonstrated substantial geometric agreement and resulted in good dosimetric agreement for all dose-volume histogram parameters except bladder D0.1cc. Small delineation differences in high-dose regions by the posterior bladder wall may explain these results. The delineation of sigmoid showed fair geometric agreement. The higher dosimetric variability for sigmoid compared with rectum and bladder did not correlate with higher variability in the total brachytherapy dose but rather may be due to the sigmoid being positioned in low-dose regions in the cases analyzed in this study., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Purpose: To present evidence-based guidelines for adjuvant radiation in the treatment of endometrial cancer., Methods and Materials: Key clinical questions to be addressed in this evidence-based guideline on endometrial cancer were identified. A comprehensive literature review was performed to identify studies that included no adjuvant therapy, or pelvic radiation or vaginal brachytherapy with or without systemic chemotherapy. Outcomes included local control, survival rates, and overall assessment of quality of life., Results: Patients with grade 1 or 2 cancers with either no invasion or <50% myometrial invasion (MI), especially when no other high risk features are present, can be safely observed after hysterectomy. Vaginal cuff brachytherapy is as effective as pelvic radiation therapy at preventing vaginal recurrence for patients with grade 1 or 2 cancers with ≥50% MI or grade 3 tumors with <50% MI. Patients with grade 3 cancer with ≥50% MI or cervical stroma invasion may benefit from pelvic radiation to reduce the risk of pelvic recurrence. There is limited evidence for a benefit to vaginal cuff brachytherapy following pelvic radiation. Multimodality treatment is recommended for patients with positive nodes or involved uterine serosa, ovaries or fallopian tubes, vagina, bladder, or rectum., Conclusions: External beam and vaginal brachytherapy remain integral aspects of adjuvant therapy for endometrial cancer., (Copyright © 2014 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.)

Purpose: To determine rates of nodal control and survival in patients with endometrial cancer treated with intensity modulated radiation therapy (IMRT) with dose escalation to unresected nodal disease., Methods and Materials: Between November 2005 and April 2011, 22 endometrial-cancer patients received IMRT with dose escalation to gross nodal disease with curative intent. Twelve were treated for recurrent disease (RD) and 10 in the primary setting, of whom 5 had a hysterectomy. The boost area included pelvic nodes in 9 patients (41%), paraaortic nodes (PAN) in 6 (27%) and both pelvic and PAN in 7 (32%). The median gross nodal dose was 63 Gy (range, 55-65). Rates of local control, disease-free survival (DFS) and overall survival (OS) were determined using the Kaplan-Meier method., Results: Median follow-up time was 37.6 months (range, 10-88). Median nodal size was 2.25 cm (range, 1-6.9). The median time to first relapse after IMRT was 12 months (range, 6-49). Relapses occurred in 5/12 RD (42%), 1/5 hysterectomy (20%), and 5/5 inoperable cases. Nodal relapses occurred in-field in 3/12 RD and 1/5 hysterectomy patients. At 3 years, nodal control was 86%, DFS was 58% and OS was 68%. Three patients experienced grade 3 late hematologic toxicity (anemia). No late grade ≥3 gastrointestinal or genitourinary toxicity occurred., Conclusions: In endometrial cancer, the use of IMRT for dose escalation to gross nodal disease is feasible with acceptable rates of toxicity. Patients with nodal recurrence or unresectable nodal disease after a hysterectomy may benefit from radiation dose escalation., (© 2013.)

Purpose: To evaluate clinical outcomes for women with recurrent endometrial cancer treated with 3D image-guided brachytherapy, Methods and Materials: 44 women, of whom 13 had received prior RT, received salvage RT for vaginal recurrence from 9/03 to 8/11. HDR or LDR interstitial brachytherapy was performed under MR or CT guidance in 35 patients (80%); 9 (20%) had CT-guided HDR cylinder brachytherapy. The median cumulative dose in EQD2 was 75.5 Gy. Actuarial estimates of local failure (LF), disease-free (DFS) and overall survival (OS) were calculated by Kaplan-Meier., Results: Histologic subtypes were endometrioid (EAC, 33), papillary serous/clear cell (UPSC/CC, 5) and carcinosarcoma (CS, 6). The 2-year DFS/OS rates were 75%/89% for EAC and 11%/24% for UPSC/CC/CS (both p<0.01). On MVA, high tumor grade was associated with recurrence (HR 3.2 for grade 2, 9.6 for grade 3, p<0.01). The LF rate at 2 years was 4% for patients without versus 39% for those with prior RT (p=0.1). Patients who had prior RT received lower cumulative doses at recurrence (66.5 Gy vs. 74.4 Gy, p<0.01). The 2-year DFS/OS rates with and without prior RT were 26%/55% and 72%/80% (both p=0.1). Four patients (9%) experienced grade 3 late toxicity, including 3 of 13 (23%) in the re-irradiation setting and 1 of 31 (3%) with no prior radiotherapy., Discussion: 3D image-guided brachytherapy results in excellent local control for women with recurrent endometrial cancer, particularly with cumulative EQD2 doses greater than 70 Gy. Successful salvage of vaginal recurrence is related to tumor grade and histologic subtype., (© 2013.)

Purpose: Given the complicated nature of an interstitial gynecologic brachytherapy treatment plan, the use of a quantitative tool to evaluate the quality of the achieved metrics compared to clinical practice would be advantageous. For this purpose, predictive mathematical models to predict the D2cc of rectum and bladder in interstitial gynecologic brachytherapy are discussed and validated., Methods: Previous plans were used to establish the relationship between D2cc and the overlapping volume of the organ at risk with the targeted area (C0) or a 1-cm expansion of the target area (C1). Three mathematical models were evaluated: D2cc = α*C1 + β (LIN); D2cc = α - exp(-β*C0) (EXP); and a mixed approach (MIX), where both C0 and C1 were inputs of the model. The parameters of the models were optimized on a training set of patient data, and the predictive error of each model (predicted D2cc - real D2cc) was calculated on a validation set of patient data. The data of 20 patients were used to perform a K-fold cross validation analysis, with K = 2, 4, 6, 8, 10, and 20., Results: MIX was associated with the smallest mean prediction error <6.4% for an 18-patient training set; LIN had an error <8.5%; EXP had an error <8.3%. Best case scenario analysis shows that an error ≤ 5% can be achieved for a ten-patient training set with MIX, an error ≤ 7.4% for LIN, and an error ≤ 6.9% for EXP. The error decreases with the increase in training set size, with the most marked decrease observed for MIX., Conclusions: The MIX model can predict the D2cc of the organs at risk with an error lower than 5% with a training set of ten patients or greater. The model can be used in the development of quality assurance tools to identify treatment plans with suboptimal sparing of the organs at risk. It can also be used to improve preplanning and in the development of real-time intraoperative planning tools.

Purpose: To evaluate clinical outcomes of CT-guided high-dose-rate (HDR) interstitial brachytherapy for primary and recurrent gynecologic cancer., Methods and Materials: Records were reviewed for 68 women (34 with primary disease and 34 with recurrence) treated with CT-guided HDR interstitial brachytherapy between May 2005 and September 2011. Interstitial application was performed under general anesthesia using an iterative approach of catheter insertion and adjustment with serial image acquisition by CT in a dedicated brachytherapy suite. The median fractional brachytherapy dose was 3.9Gy delivered twice daily in seven fractions. The median cumulative dose in equivalent 2-Gy fractions was 74.8Gy. Actuarial survival estimates were calculated using the Kaplan-Meier method, and toxicity was reported by Common Toxicity Criteria., Results: Primary disease sites were endometrial (34), cervical (17), vaginal (11), ovarian (3), and vulvar (3). Median age was 61.5 years, and tumor size at diagnosis was 3.4cm. Median D90 and V100 were 73.6Gy and 87.5%, respectively; median D2cc for bladder, rectum, and sigmoid were 67.1, 64.6, and 53.7Gy, respectively. With a median followup of 17 months, actuarial rates of local control, progression-free survival, and overall survival at 2 years for all patients were 86%, 60%, and 64%, respectively. There were 9 grade 3 late toxicities (six gastrointestinal and three vulvovaginal)., Conclusions: HDR interstitial brachytherapy with CT-guided catheter placement results in acceptable local control, toxicity, and survival rates for women with primary or recurrent gynecologic cancer. Durable pelvic control may be achieved in most patients with this specialized brachytherapy technique., (Copyright © 2013 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.)