Multi-catheter Breast Brachytherapy Research Articles

MSOR09 Presentation Time: 9:10 AM: Improving Treatment Quality in Multi-Catheter Breast Brachytherapy by Decision-Tree Based Treatment Adaption and Implementation of Patient Immobilization

MSOR09 Presentation Time: 9:10 AM: Improving Treatment Quality in Multi-Catheter Breast Brachytherapy by Decision-Tree Based Treatment Adaption and Implementation of Patient Immobilization

Investigating the impact of breast positioning control on physical treatment parameters in multi-catheter breast brachytherapy

PurposeTo assess the effects of a workflow for reproducible patient and breast positioning on implant stability during high-dose-rate multi-catheter breast brachytherapy.MethodsThirty patients were treated with our new positioning control workflow. Implant stability was evaluated based on a comparison of planning-CTs to control-CTs acquired halfway through the treatment. To assess geometric stability, button–button distance variations as well as Euclidean dwell position deviations were evaluated. The latter were also quantified within various separated regions within the breast to investigate the location-dependency of implant alterations. Furthermore, dosimetric variations to target volume and organs at risk (ribs, skin) as well as isodose volume changes were analyzed. Results were compared to a previously treated cohort of 100 patients.ResultsWith the introduced workflow, the patient fraction affected by button–button distance variations > 5 mm and by dwell position deviations > 7 mm were reduced from 37% to 10% and from 30% to 6.6%, respectively. Implant stability improved the most in the lateral to medial breast regions. Only small stability enhancements were observed regarding target volume dosimetry, but the stability of organ at risk exposure became substantially higher. D0.2ccm skin dose variations > 12.4% and D0.1ccm rib dose variations > 6.7% were reduced from 11% to 0% and from 16% to 3.3% of all patients, respectively.ConclusionBreast positioning control improved geometric and dosimetric implant stability for individual patients, and thus enhanced physical plan validity in these cases.

On the implant stability in adaptive multi-catheter breast brachytherapy: Establishment of a decision-tree for treatment re-planning

Background and purposeTo assess implant stability and identify causes of implant variations during high-dose-rate multi-catheter breast brachytherapy. Materials and methodsPlanning-CTs were compared to control-CTs acquired halfway through the treatment for 100 patients. For assessing geometric stability, Fréchet-distance and button-to-button distance changes of all catheters as well as variations of Euclidean distances and convex hulls of all dwell positions were determined. The CTs were inspected to identify the causes of geometric changes. Dosimetric effects were evaluated by target volume transfers and re-contouring of organs at risk. The dose non-uniformity ratio (DNR), 100% and 150% isodose volumes (V100 and V150), coverage index (CI), and organ doses were calculated. Correlations between the examined geometric and dosimetric parameters were assessed. ResultsFréchet-distance and dwell position deviations >2.5 mm as well as button-to-button distance changes >5 mm were detected for 5%, 2%, and 6.3% of catheters, but for 32, 17, and 37 patients, respectively. Variations occurred enhanced in the lateral breast and close to the ribs, e.g. due to different arm positions. Only small dosimetric effects with median DNR, V100, and CI variations of −0.01 ± 0.02, (−0.5 ± 1.3)ccm, and (–1.4 ± 1.8)% were observed in general. Skin dose exceeded recommended levels for 12 of 100 patients. Various correlations between geometric and dosimetric implant stability were found, based on which decision-tree regarding treatment re-planning was established. ConclusionMulti-catheter breast brachytherapy shows a high implant stability in general, but considering skin dose changes is important. To increase implant stability for individual patients, we plan to investigate patient immobilization aids during treatments.

Interstitial multi-catheter breast brachytherapy: Technical aspects and experience feedback in a comprehensive cancer center

PurposeTo focus on technical aspects of the implementation of interstitial high dose rate brachytherapy, with a step-by-step approach. Materials and methodsPatients were selected during multidisciplinary tumor boards, according to inclusion criteria adapted from GEC-ESTRO guidelines. A CT scan was performed a few days before implantation. On pre-implant CT, using surgical scar and clips, surgical and pathological reports, and preoperative images, we delineated the tumor bed to be included in the Clinical Target Volume (CTV), according to GEC ESTRO Recommendations. A 3D virtual implant simulation of the best catheter positions was performed in order to cover the target volume. Implantation was then carried out under local anaesthetic using 3D projections of the catheter inlets and outlets. Dosimetry was performed on post-implantation CT scan. A dose of 34Gy was delivered in 10 fractions. Acute and late side effects, and local control were evaluated 2 and 8 months after treatment. ResultsBetween July 2017 and January 2020, 20 patients were treated with accelerated partial breast irradiation. Dose constraints regarding target volume coverage, overdose, dose homogeneity, conformation index and organs at risk were met in 94.7%, 100%, 63.2%, 0% and 89.5% of the treatment plans, respectively. Grade 1-2 acute adverse events were observed in 21% of patients, with no grade 3-4 events. ConclusionThe first dosimetric results and early clinical tolerance and efficacy achieved by the implementation of breast interstitial multicatheter brachytherapy in routine clinical practice are very encouraging, and confirm the interest of extending this practice.

Is adaptive treatment planning in multi-catheter interstitial breast brachytherapy necessary?

PurposeFor 55 patients treated with interstitial multi-catheter breast brachytherapy the need for adaptive treatment planning was assessed. Methods and materialsFor all patients a treatment planning computed tomography (CT) and a follow-up CT were acquired and used for the retrospective evaluation. Keeping dwell time and dwell positions constant, the treatment plan assessed directly after catheter implantation was compared to the situation 48 h after implantation. Both manual catheter reconstructions, based on the planning and follow-up CT, were rigid registered to each other and the resulting deviations analyzed, like the difference between corresponding dwell positions (ΔDP) or the discrete Fréchet distance. Further, the dosimetric changes, e.g., coverage index (ΔCI), conformal index (ΔCOIN) and dose non-uniformity ratio (ΔDNR) were considered for a deformed planning target volume (PTV) and the rigid warped PTV structure. The PTV was deformed according to the vector field estimated between the two acquired CTs. ResultsOver all patients with rigid aligned CTs a mean ΔDP, ΔCI, ΔCOIN and ΔDNR were determined to 2.41 ± 1.73 mm, 3.10 ± 3.17%, 0.009 ± 0.007 and 0.036 ± 0.040, respectively. Considering the deformed PTV ΔCI was estimated to 5.05 ± 4.14%. ConclusionIn conclusion, in 4% of the cases re-planning would have been beneficial to ensure the planned dose delivery. Large PTV changes or large DP deviations were found to be the main reasons for dosimetric variations.

Estimation of inter-fractional variations in interstitial multi-catheter breast brachytherapy using a hybrid treatment delivery system

PurposeIrradiation of the tumor bed using interstitial multi-catheter brachytherapy is one of the treatment options for breast cancer patients. In order to ensure the planned dose delivery an advanced quality intervention method using an electromagnetic tracking (EMT) system is presented. The system is used to assess inter-fractional variations within the framework of a patient study. Methods and materialsUntil now 41 patients were included in the study for the evaluation and overall 355 EMT measurements were performed. The catheter traces are measured automatically and sequentially using an afterloader prototype (Flexitron, Elekta, Veenendaal, The Netherlands) equipped with an EMT sensor. The implant geometry is tracked directly after implantation, after CT imaging and after each irradiation fraction. The acquired data is rigidly registered to the catheter traces defined in the treatment plan and the dwell positions (DP) are reconstructed. DPs defined in treatment planning serve as reference. Breathing motion was corrected and recorded using three reference 6DoF sensors placed on the patients’ skin. The Euclidean distance between the planned and reconstructed DPs provides information about possible inter-fractional deviations. Further, the influence of various factors on the occurrence of large deviations was investigated, like the patients’ age, the length of the catheter, the breast volume, etc. ResultsOver all patient measurements a median Euclidean distance of 2.19 mm was determined between the reconstructed DPs and the reference DPs. The median deviation combining all datasets was minimal (1.67 mm) at the measurement directly after CT imaging. The deviations between the different fractions have a median distance of 2.31 mm which could be improved to 2.05 mm by adapting the treatment plan according to the follow-up CT. No correlation between the distance to the skin, ribs, mammilla or the breast volume and the occurrences of large deviations was found. The largest deviations were determined in the upper inner quadrant of the breast. ConclusionThe afterloader prototype could be well integrated into the clinical routine and is beneficial for ensuring the quality of the brachytherapy. Overall, a small median DP deviation, lower than the used step size of 2.5 mm, was detected.

Predictive Factors for Keloid Amongst Patients of Different Ethnicity Undergoing Multicatheter Breast Brachytherapy

To determine the incidence and predictive factors for keloids in a multiracial population undergoing breast brachytherapy.

Quality of life after multicatheter breast brachytherapy

Quality of life after multicatheter breast brachytherapy

ESTRO-ACROP guideline: Interstitial multi-catheter breast brachytherapy as Accelerated Partial Breast Irradiation alone or as boost – GEC-ESTRO Breast Cancer Working Group practical recommendations

PurposeThis consensus statement from the Breast Cancer Working Group of Groupe Européen de Curiethérapie of European Society for Radiotherapy and Oncology (GEC-ESTRO) aims at generating practical guidelines for multi-catheter image-guided brachytherapy in the conservative management of breast cancer patients used for either Accelerated Partial Breast Irradiation (APBI) or for a breast boost. MethodsRecent advances in techniques of multi-catheter brachytherapy were summarized and all the relevant literature was reviewed by a panel of experts. Panel members of the GEC-ESTRO experts participated in a series of conferences, supplemented their clinical experience, were surveyed to determine their current practices and patterns, performed a literature review, and formulated recommendations for implementing APBI with multi-catheter brachytherapy, focusing on treatment planning issues, catheter insertion, dosimetry and quality assurance. This document was reviewed and approved by the full panel, the GEC-ESTRO executive board and by the ACROP (Advisory Committee on Radiation Oncology Practice). ResultsThree-dimensional (3D) treatment planning, catheter insertion techniques, dosimetry and methods of quality assurance for APBI and boost with multi-catheter image-guided brachytherapy after breast conserving surgery are described. Detailed recommendations for daily practice including dose constraints are given. ConclusionsRecent standards and guidelines for the use of APBI with different multi-catheter image-guided brachytherapy techniques have been defined. Different techniques are used to insert the catheters. Guidelines are mandatory to assure precise catheter insertion for coverage of the target volume and to guarantee high-quality dosimetry. The same rules apply for brachytherapy based boost irradiation for breast cancer after whole breast irradiation as well as for partial breast re-irradiation.

Initial Evaluation of Multicatheter Brachytherapy Technique for Lumpectomy Cavity Boost

Lumpectomy cavity radiotherapy boost after breast conserving surgery and whole breast irradiation reduces local cancer recurrence. This boost is typically delivered with external beam photons or electrons, encompassing the postoperative surgical cavity and a surrounding margin of normal breast tissue. External beam radiotherapy boost correlates with increased rates of breast fibrosis and may impair cosmetic outcomes. Multicatheter breast brachytherapy (MCBB) is an approach to deliver dose-escalated high dose rate radiation to the lumpectomy cavity while limiting additional radiation exposure to normal breast tissue and adjacent organs. This study evaluates the feasibility of using a multicatheter brachytherapy approach for cavity boost when combined with whole breast external beam radiotherapy.

Recommendations from GEC ESTRO Breast Cancer Working Group (II): Target definition and target delineation for accelerated or boost partial breast irradiation using multicatheter interstitial brachytherapy after breast conserving open cavity surgery

ObjectiveTo prepare guidelines for target definition and delineations after open cavity breast conserving surgery in accelerated partial breast irradiations or boost treatments using multicatheter interstitial brachytherapy based on the consensus of the Breast Working Group of GEC-ESTRO. MethodFollowing a study on interobserver variations of target volume delineation in multicatheter breast brachytherapy after open cavity surgery and a number of discussions in consensus meetings these guidelines were worked out by experts on the field. Proposed recommendations(1) Consistent windowing has to be used for proper cavity visualization. (2) The cavity visualization score has to be at least 3 in order to minimize the interobserver variations of target definition. (3) At delineation of surgical cavity only the homogeneous part of the postoperative seroma has to be included in the contours and protrusions or sharp irregularities have to be excluded. When surgical clips are present, they have to be surrounded by the contour with close contact. (4) CTV is created from the outlined surgical cavity with a nonisotropic geometrical extension. In each direction the safety margin is calculated by taking into account the size of the free resection margin. The total size of safety margin is always 20mm which is the sum of the surgical and added safety margins. CTV is limited to chest wall/pectoral muscles and 5mm below the skin surface. ConclusionFollowing these guidelines the target volume definition in breast brachytherapy after open cavity surgery is expected to be accomplished in more consistent way with low interobserver variations.

BrachyGuide: a brachytherapy-dedicated DICOM RT viewer and interface to Monte Carlo simulation software.

This work presents BrachyGuide, a brachytherapy‐dedicated software tool for the automatic preparation of input files for Monte Carlo simulation from treatment plans exported in DICOM RT format, and results of calculations performed for its benchmarking. Three plans were prepared using two computational models, the image series of a water sphere and a multicatheter breast brachytherapy patient, for each of two commercially available treatment planning systems: BrachyVision and Oncentra Brachy. One plan involved a single source dwell position of an 192Ir HDR source (VS2000 or mHDR‐v2) at the center of the water sphere using the TG43 algorithm, and the other two corresponded to the TG43 and advanced dose calculation algorithm for the multicatheter breast brachytherapy patient. Monte Carlo input files were prepared using BrachyGuide and simulations were performed with MCNP v.6.1. For the TG43 patient plans, the Monte Carlo computational model was manually edited in the prepared input files to resemble TG43 dosimetry assumptions. Hence all DICOM RT dose exports were equivalent to corresponding simulation results and their comparison was used for benchmarking the use of BrachyGuide. Monte Carlo simulation results and corresponding DICOM RT dose exports agree within type A uncertainties in the majority of points in the computational models. Treatment planning system, algorithm, and source specific differences greater than type A uncertainties were also observed, but these were explained by treatment planning system‐related issues and other sources of type B uncertainty. These differences have to be taken into account in commissioning procedures of brachytherapy dosimetry algorithms. BrachyGuide is accurate and effective for use in the preparation of commissioning tests for new brachytherapy dosimetry algorithms as a user‐oriented commissioning tool and the expedition of retrospective patient cohort studies of dosimetry planning.PACS numbers: 87.53.Bn, 87.53.Jw, 87.55.D‐, 87.55.Qr, 87.55.km, 87.55.K‐

PO-1003: Comparing dosimetric outcomes of two different insertion methods for multicatheter breast brachytherapy

PO-1003: Comparing dosimetric outcomes of two different insertion methods for multicatheter breast brachytherapy

Development of a scatter correction technique and its application to HDR I192r multicatheter breast brachytherapy

This article introduces a scatter correction (SC) technique for high-dose-rate (HDR) 192Ir brachytherapy dose calculations in the absence of a full scatter environment near the skin. The technique uses dosimetry data derived by Monte Carlo (MC) simulations for the Nucletron microSelectron v2 HDR 192Ir source. The data include the primary and scatter components of the radial dose function and the anisotropy function in addition to a SC table. The dose to a point of interest for each dwell position is estimated by first calculating the primary and scatter doses in an infinite water phantom. The scatter dose is then scaled by a SC factor that depends on the distances between the point of interest, the dwell positions, and the body contour of the patient. SC calculations in water phantoms of three different shapes, as well as computed tomography-based geometries of 18 multicatheter breast patients, are compared with Task Group 43 (TG-43) and PTRAN_CT MC calculations. The SC calculations show improvement over TG-43 for all test cases while taking 50% longer to run. The target and skin doses for the breast patient plans are unaffected by tissue inhomogeneities, as indicated by an agreement better than 1% between the SC and MC results. On average, TG-43 overestimates the target coverage by 2% and the dose to the hottest 0.1 cm3 (D0.1 cc) of the skin by 5%. The low-density lung causes the lung and heart D0.1 cc to differ by up to 3% for the SC method and by 2%-5% for TG-43 compared with MC calculations. The SC technique is suitable for HDR 192Ir dose calculations near the skin provided that the dose is nearly unperturbed by internal inhomogeneities. It has been validated for multicatheter breast brachytherapy.

Dosimetric correlation of clinical fat necrosis in patients treated with multi-catheter breast brachytherapy

Purpose: To evaluate the correlation of dosimetric variables with development of clinical fat necrosis in patients treated with image-guided high-dose-rate (HDR) multi-catheter accelerated partial breast irradiation (APBI) with 3D CT-based treatment planning.

Dosimetric performance of SAVI: A new single-entry, multi-catheter breast brachytherapy applicator

Purpose: The objective of this study was to evaluate the dosimetric performance and clinical utility of the Strut Adjusted Volume Implant (SAVI) applicator when used as the sole method of radiation therapy for patients with early carcinoma of the breast.

Multi-catheter Breast Brachytherapy Following Lumpectomy in Select Early Stage Breast Cancer Patients: The University of Wisconsin Experience

Multi-catheter Breast Brachytherapy Following Lumpectomy in Select Early Stage Breast Cancer Patients: The University of Wisconsin Experience