102 results on '"Niatsetski, Y"'
Search Results
2. Automated optimization for cervix brachytherapy requires more than the EMBRACE-II planning aims
- Author
-
Dickhoff, L., Kerkhof, E.M., Pieters, B.R., Westerveld, H., Stalpers, L.J., Velema, L.A., Barten, D.L., Andel, H.G. van, Niatsetski, Y., Creutzberg, C.L., Bosman, P.A., and Alderliesten, T.
- Published
- 2022
3. PO-0233 A multi-protocol validation study of automated bi-objective planning for HDR prostate brachytherapy
- Author
-
Bouter, A., primary, Alderliesten, T., additional, Pieters, B.R., additional, Buus, S., additional, Niatsetski, Y., additional, and Bosman, P.A., additional
- Published
- 2021
- Full Text
- View/download PDF
4. PO-0216 Healthy tissue constraints for catheter position optimization in HDR prostate brachytherapy planning
- Author
-
van der Meer, M.C., primary, van Dorth, D., additional, Bosman, P.A., additional, Pieters, B.R., additional, Niatsetski, Y., additional, Alderliesten, T., additional, and Bel, A., additional
- Published
- 2021
- Full Text
- View/download PDF
5. PO-0214 Investigation of obstructions in ring applicators during pulsed dose rate cervix brachytherapy
- Author
-
Menon, G., primary, Long, B., additional, Petit, R., additional, Zimmer, J., additional, Gadbois, K., additional, Niatsetski, Y., additional, Wiebe, E., additional, Cuartero, J., additional, Huang, F., additional, and Yip, E., additional
- Published
- 2021
- Full Text
- View/download PDF
6. PO-0200 Comparison of catheter position planning algorithms for HDR prostate brachytherapy under uncertainty
- Author
-
van der Meer, M.C., primary, Pieters, B.R., additional, Niehoff, P., additional, Milickovic, N., additional, Niatsetski, Y., additional, Alderliesten, T., additional, Bosman, P.A., additional, and Bel, A., additional
- Published
- 2021
- Full Text
- View/download PDF
7. Robust optimization for HDR prostate brachytherapy applied to organ reconstruction uncertainty
- Author
-
Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), and Bel, A. (Arjan)
- Abstract
Purpose. Recently, we introduced a bi-objective optimization approach based on dose-volume indices to automatically create clinically goodHDRprostate brachytherapy plans. To calculate dose-volume indices, a reconstruction algorithm is used to determine the 3D organ shape from 2D contours, inevitably containing settings that influence the result.Weaugment the optimization approach to quickly find plans that are robust to differences in 3D reconstruction. Methods. Studied reconstruction settings were: Interpolation between delineated organ contours, overlap between contours, and organ shape at the top and bottom contour. Two options for each setting yields 8 possible 3D organ reconstructions per patient, over which the robust model defines minimax optimization. For the original model, settings were based on our treatment planning system. Both models were tested on data of 26 patients and compared by re-evaluating selected optimized plans both in the original model (1 organ reconstruction, the difference determines the cost), and in the robust model (8 organ reconstructions, the difference determines the benefit). Results. Robust optimization increased the run time from 3 to 6 min. The median cost for robust optimization as observed in the original model was-0.25% in the dose-volume indices with a range of [-0.01%,-1.03%]. The median benefit of robust optimization as observed in the robust model was 0.93% with a range of [0.19%, 4.1
- Published
- 2021
- Full Text
- View/download PDF
8. On the use of the absorbed depth-dose measurements in the beam calibration of a surface electronic high-dose-rate brachytherapy unit, a Monte Carlo-based study
- Author
-
Valdes-Cortez C, Niatsetski Y, Ballester F, Vijande J, Candela-Juan C, and Perez-Calatayud J
- Subjects
digestive, oral, and skin physiology ,Monte Carlo simulation, beam calibration, dosimetry, electronic brachytherapy - Abstract
To evaluate the use of the absorbed depth-dose as a surrogate of the half-value layer in the calibration of a high-dose-rate electronic brachytherapy (eBT) equipment. The effect of the manufacturing tolerances and the absorbed depth-dose measurement uncertainties in the calibration process are also addressed.
- Published
- 2020
9. Surface brachytherapy: Joint report of the AAPM and the GEC-ESTRO Task Group No. 253
- Author
-
Fulkerson RK, Perez-Calatayud J, Ballester F, Buzurovic I, Kim Y, Niatsetski Y, Ouhib Z, Pai S, Rivard MJ, Rong Y, Siebert FA, Thomadsen BR, and Weigand F
- Subjects
skin brachytherapy, surface applicator QA, surface brachytherapy - Abstract
The surface brachytherapy Task Group report number 253 discusses the common treatment modalities and applicators typically used to treat lesions on the body surface. Details of commissioning and calibration of the applicators and systems are discussed and examples are given for a risk-based analysis approach to the quality assurance measures that are necessary to consider when establishing a surface brachytherapy program.
- Published
- 2020
10. Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteya® unit: a Monte Carlo study
- Author
-
Valdes-Cortez C, Ballester F, Vijande J, Gimenez V, Gimenez-Alventosa V, Perez-Calatayud J, Niatsetski Y, and Andreo P
- Subjects
Monte Carlo, dosimetry, eBT, electronic brachytherapy, ionization chamber - Abstract
Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit. Monte Carlo simulations using the PENELOPE-2018 system were performed to determine the absorbed dose deposited in water and in the chamber sensitive volume at different depths with a Type A uncertainty smaller than 0.1%. Chamber-to-chamber differences have been explored performing measurements using three different chambers. The range of conical applicators available, from 10 to 30 mm in diameter, has been explored. Using a depth-independent global chamber perturbation correction factor without a shift of the effective point of measurement yielded differences between the absorbed dose to water and the corrected absorbed dose in the sensitive volume of the chamber of up to 1% and 0.6% for the 10 mm and 30 mm applicators, respectively. Calculations using a depth-dependent perturbation factor, including or excluding a shift of the effective point of measurement, resulted in depth-dose differences of about $\pm0.5\%$ or less for both applicators. The smallest depth-dose differences were obtained when a shift of the effective point of measurement was implemented, being displaced 0.4~mm towards the center of the sensitive volume of the chamber. The correction factors were obtained with combined uncertainties of 0.4 % (k = 2). Uncertainties due to chamber-to-chamber differences are found to be lower than 2%. The results emphasize the relevance of carrying out detailed Monte Carlo studies for each electronic brachytherapy device and ionization chamber used for its dosimetry.
- Published
- 2020
11. Bi-objective optimization of catheter positions for high-dose-rate prostate brachytherapy
- Author
-
Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Wieringen, N. (Niek) van, Pieters, B.R. (Bradley), Bel, A. (Arjan), Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Wieringen, N. (Niek) van, Pieters, B.R. (Bradley), and Bel, A. (Arjan)
- Abstract
Purpose: Bi-objective simultaneous optimization of catheter positions and dwell times for high-dose-rate (HDR) prostate brachytherapy, based directly on dose-volume indices, has shown promising results. However, optimization with the state-of-the-art evolutionary algorithm MO-RV-GOMEA so far required several hours of runtime, and resulting catheter positions were not always clinically feasible. The aim of this study is to extend the optimization model and apply GPU parallelization to achieve clinically acceptable computation times. The resulting optimization procedure is compared with a previously introduced method based solely on geometric criteria, the adapted Centroidal Voronoi Tessellations (CVT) algorithm. Methods: Bi-objective simultaneous optimiza
- Published
- 2020
- Full Text
- View/download PDF
12. Robust evolutionary bi-objective optimization for prostate cancer treatment with high-dose-rate brachytherapy
- Author
-
Meer, M.C. (Marjolein) van der, Bel, A. (Arjan), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bosman, P.A.N. (Peter), Meer, M.C. (Marjolein) van der, Bel, A. (Arjan), Niatsetski, Y. (Yury), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), and Bosman, P.A.N. (Peter)
- Abstract
We address the real-world problem of automating the design of high-quality prostate cancer treatment plans in case of high-dose-rate brachytherapy, a form of internal radiotherapy. For this, recently a bi-objective real-valued problem formulation was introduced. With a GPU parallelization of the Multi-Objective Real-Valued Gene-pool Optimal Mixing Evolutionary Algorithm (MO-RV-GOMEA), good treatment plans were found in clinically acceptable running times. However, optimizing a treatment plan and delivering it to the patient in practice is a two-stage decision process and involves a number of uncertainties. Firstly, there is uncertainty in the identified organ boundaries due to the limited resolution of the medical images. Secondly, the treatment involves placing catheters inside the patient, which always end up (slightly) different from what was optimized. An important factor is therefore the robustness of the final treatment plan to these uncertainties. In this work, we show how we can extend the evolutionary optimization approach to find robust plans using multiple scenarios without linearly increasing the amount of required computation effort, as well as how to deal with these uncertainties efficiently when taking into account the sequential decision-making moments. The performance is tested on three real-world patient cases. We find that MO-RV-GOMEA is equally well capable of solving the more complex robust problem formulation, resulting in a more realistic reflection of the treatment plan quali
- Published
- 2020
- Full Text
- View/download PDF
13. Automatic bi-objective parameter tuning for inverse planning of high-dose-rate prostate brachytherapy
- Author
-
Maree, S.C. (Stef), Bosman, P.A.N. (Peter), Wieringen, N. (Niek) van, Niatsetski, Y. (Yury), Pieters, B.R. (Bradley), Bel, A. (Arjan), Alderliesten, T. (Tanja), Maree, S.C. (Stef), Bosman, P.A.N. (Peter), Wieringen, N. (Niek) van, Niatsetski, Y. (Yury), Pieters, B.R. (Bradley), Bel, A. (Arjan), and Alderliesten, T. (Tanja)
- Abstract
We present an automatic bi-objective parameter-tuning approach for inverse planning methods for high-dose-rate prostate brachytherapy, which aims to overcome the difficult and time-consuming manual parameter tuning that is currently required to obtain patient-specific high-quality treatment plans. We modelled treatment planning as a bi-objective optimization problem, in which dose-volume-based planning criteria related to target coverage are explicitly separated from organ-sparing criteria. When this model is optimized, a large set of high-quality plans with different trade-offs can be obtained. This set can be visualized as an insightful patient-specific trade-off curve. In our parameter-tuning approach, the parameters of inverse planning methods are automatically tuned, aimed to maximize the two objectives of the bi-objective planning model. By generating trade
- Published
- 2020
- Full Text
- View/download PDF
14. Automatic bi-objective parameter tuning for inverse planning of high-dose-rate prostate brachytherapy
- Author
-
Maree, S C, primary, Bosman, P A N, additional, van Wieringen, N, additional, Niatsetski, Y, additional, Pieters, B R, additional, Bel, A, additional, and Alderliesten, T, additional
- Published
- 2020
- Full Text
- View/download PDF
15. A Monte Carlo-based dosimetric characterization of Esteya((R)), an electronic surface brachytherapy unit
- Author
-
Valdes-Cortez, C, Niatsetski, Y, Perez-Calatayud, J, Ballester, F, and Vijande, J
- Subjects
dosimetry ,electronic brachytherapy ,simulation efficiency ,surface treatment ,x-ray source ,Monte Carlo simulation - Abstract
Purpose The purpose of this work is threefold: First, to obtain the phase space of an electronic brachytherapy (eBT) system designed for surface skin treatments. Second, to explore the use of some efficiency enhancing (EFEN) strategies in the determination of the phase space. Third, to use the phase space previously obtained to perform a dosimetric characterization of the Esteya eBT system. Methods The Monte Carlo study of the 69.5 kVp x-ray beam of the Esteya((R)) unit (Elekta Brachytherapy, Veenendaal, The Netherlands) was performed with PENELOPE2014. The EFEN strategies included the use of variance reduction techniques and mixed Class II simulations, where transport parameters were fine-tuned. Four source models were studied varying the most relevant parameters characterizing the electron beam impinging the target: the energy spectrum (mono-energetic or Gaussian shaped), and the electron distribution over the focal spot (uniform or Gaussian shaped). Phase spaces obtained were analyzed to detect differences in the calculated data due to the EFEN strategy or the source configuration. Depth dose curves and absorbed dose profiles were obtained for each source model and compared to experimental data previously published. Results In our EFEN strategy, the interaction forcing variance reduction (VRIF) technique increases efficiency by a factor similar to 20. Tailoring the transport parameters values (C1 and C2) does not increase the efficiency in a significant way. Applying a universal cutoff energy EABS of 10 keV saves 84% of CPU time while showing negligible impact on the calculated results. Disabling the electron transport by imposing an electron energy cutoff of 70 keV (except for the target) saves an extra 8% (losing in the process 1.2% of the photons). The Gaussian energy source (FWHM = 10%, centered at the nominal kVp, homogeneous electron distribution) shows characteristic K-lines in its energy spectrum, not observed experimentally. The average photon energy using an ideal source (mono-energetic, homogeneous electron distribution) was 36.19 +/- 0.09 keV, in agreement with the published measured data of 36.2 +/- 0.2 keV. The use of a Gaussian-distributed electron source (mono-energetic) increases the penumbra by 50%, which is closer to the measurement results. The maximum discrepancy of the calculated percent depth dose with the corresponding measured values is 4.5% (at the phantom surface, less than 2% beyond 1 mm depth) and 5% (for the 80% of the field) in the dose profile. Our results agree with the findings published by other authors and are consistent within the expected Type A and B uncertainties. Conclusions Our results agree with the published measurement results within the reported uncertainties. The observed differences in PDD, dose profiles, and photon spectrum come from three main sources of uncertainty: intermachine variations, measurements, and Monte Carlo calculations. It has been observed that a mono-energetic source with a Gaussian electron distribution over the focal spot is a suitable choice to reproduce the experimental data.
- Published
- 2019
16. Fast and insightful bi-objective optimization for prostate cancer treatment planning with high-dose-rate brachytherapy
- Author
-
Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), Bosman, P.A.N. (Peter), Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), and Bosman, P.A.N. (Peter)
- Abstract
Purpose: Prostate high-dose-rate brachytherapy (HDR-BT) planning involves determining the movement that a high-strength radiation stepping source travels through the patient's body, such that the resulting radiation dose distribution sufficiently covers tumor volumes and safely spares nearby healthy organs from radiation risks. The Multi-Objective Real-Valued Gene-pool Optimal Mixing Evolutionary Algorithm (MO-RV-GOMEA) has been shown to be able to effectively handle this inherent bi-objective nature of HDR-BT planning. However, in clinical practice there is a very restricted planning time budget (often less than 1 h) for HDR-BT planning, and a considerable amount of running time needs to be spent before MO-RV-GOMEA finds a good trade-off front of treatment plans (about20–30 min on a single CPU core) with sufficiently accurate dose calculations, limiting the applicability of the approach in the clinic. To address this limitation, we propose an efficiency enhancement technique for MO-RV-GOMEA solving the bi-objective prostate HDR-BT planning problem.Methods: Dose-Volume (DV) indices are often used to assess the quality of HDR-BT plans. The accuracy of these indices depends on the number of dose calculation points at which radiation doses are computed. These are randomly uniformly sampled inside target volumes and organs at risk. In available HDR-BT planning optimization algorithms, the number of dose calculation points is fixed. The more points are used, the better the accuracy of the obtained results will be, but also the longer the algorithms need to be run. In this work, we introduce a so-called multi-resolution scheme that gradually increases the number of dose calculation points during the optimization run such that the running time can be substantially reduced without compromising on the accuracy of the obtained results.Results and conclusion: Experiments on a data set of 18 patient cases show that with the multi-resolution scheme, MO-RV-GOMEA
- Published
- 2019
- Full Text
- View/download PDF
17. Sensitivity of dose-volume indices to computation settings in high-dose-rate prostate brachytherapy treatment plan evaluation
- Author
-
Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Pieters, B.R. (Bradley), Niatsetski, Y. (Yury), Wieringen, N. (Niek) van, Alderliesten, T. (Tanja), Bel, A. (Arjan), Meer, M.C. (Marjolein) van der, Bosman, P.A.N. (Peter), Pieters, B.R. (Bradley), Niatsetski, Y. (Yury), Wieringen, N. (Niek) van, Alderliesten, T. (Tanja), and Bel, A. (Arjan)
- Abstract
Purpose: To investigate the variation in computed dose-volume (DV) indices for high-dose-rate (HDR) prostate brachytherapy that can result from typical differences in computation settings in treatment planning systems (TPSs). Methods: Five factors were taken into account: number of dose-calculation points, radioactive source description, interpolation between delineated contours, intersections between delineated organ contours, and organ shape at the top and bottom contour using either full or partial slice thickness. Using in-house developed software, the DV indices of the treatment plans of 26 patients were calculated with different settings, and compared to a baseline setting that closely followed the default settings of the TPS used in our medical center. Studied organs were prostate and seminal vesicles, denoted as targets, and bladder, rectum, and urethra, denoted as organs at risk (OARs), which were delineated on MRI scans with a 3.3 mm slice thickness. Results: When sampling a fixed number of points in each organ, in order to achieve a width of the 95% confidence interval over all patients of the DV indices of 1% or less, only 32,000 points had to be sampled per target, but 256,000 points had to be sampled per OAR. For the remaining factors, DV indices changed up to 0.4% for rectum, 1.3% for urethra, and 2.6% for prostate. DV indices of the bladder changed especially if the high-dose-region was (partly) located at the most caudal contour, up to 8.5%, and DV indices of the vesicles changed especially if there were few delineated contours, up to 9.8%, both due to the use of full slice thickness for the top and bottom contour. Conclusions: The values of DV indices used in prostate HDR brachytherapy treatment planning are influenced by the computation settings in a TPS, especially at the most caudal part of the bladder, as well as in the seminal vesicles.
- Published
- 2019
- Full Text
- View/download PDF
18. GPU-accelerated bi-objective treatment planning for prostate high-dose-rate brachytherapy
- Author
-
Bouter, P.A. (Anton), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), Bosman, P.A.N. (Peter), Bouter, P.A. (Anton), Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), and Bosman, P.A.N. (Peter)
- Abstract
Purpose: The purpose of this study is to improve upon a recently introduced bi-objective treatment planning method for prostate high-dose-rate (HDR) brachytherapy (BT), both in terms of resulting plan quality and runtime requirements, to the extent that its execution time is clinically acceptable. Methods: Bi-objective treatment planning is done using a state-of-the-art multiobjective evolutionary algorithm, which produces a large number of potential treatment plans with different trade-offs between coverage of the target volumes and sparing organs at risk. A graphics processing unit (GPU) is used for large-scale parallelization of dose calculations and the calculation of the dose-volume (DV) indices of potential treatment plans. Moreover, the objectives of the previously used bi-objective optimization model are modified to produce better results. Results: We applied the GPU-accelerated bi-objective treatment planning method to a set of 18 patients, resulting in a set containing a few hundred potential treatment plans with different trade-offs for each of these patients. Due to accelerations introduced in this article, results previously achieved after 1 hour are now achieved within 30 seconds of optimization. We found plans satisfying the clinical protocol for 15 of 18 patients, whereas this was the case for only 4 of 18 clinical plans. Higher quality treatment plans are obtained when the accuracy of DV index calculation is increased using more dose calculation points, requiring still no more than 3 minutes of optimization for 100 000 points. Conclusions: Large sets of high-quality treatment plans that trade-off coverage and sparing are now achievable within 30 seconds, due to the GPU-acceleration of a previously introduced bi-objective treatment planning method for prostate HDR brachytherapy. Higher quality plans can be achieved when optimizing for 3 minutes, which we still consider to be clinically acceptable. This allows for more insightful treatment plan select
- Published
- 2019
- Full Text
- View/download PDF
19. OC-0395 Bi-objective optimization of dosimetric indices for HDR prostate brachytherapy within 30 seconds
- Author
-
Bouter, A., primary, Alderliesten, T., additional, Pieters, B.R., additional, Bel, A., additional, Niatsetski, Y., additional, and Bosman, P.A.N., additional
- Published
- 2019
- Full Text
- View/download PDF
20. OC-0396 Robust HDR prostate brachytherapy planning accounting for organ reconstruction settings
- Author
-
Van der Meer, M.C., primary, Bosman, P.A.N., additional, Pieters, B.R., additional, Niatsetski, Y., additional, Alderliesten, T., additional, and Bel, A., additional
- Published
- 2019
- Full Text
- View/download PDF
21. Better and faster catheter position optimization in HDR brachytherapy for prostate cancer using multi-objective real-valued GOMEA
- Author
-
Meer, M.C. (Marjolein) van der, Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), Bosman, P.A.N. (Peter), Meer, M.C. (Marjolein) van der, Alderliesten, T. (Tanja), Pieters, B.R. (Bradley), Bel, A. (Arjan), Niatsetski, Y. (Yury), and Bosman, P.A.N. (Peter)
- Abstract
The recently-introduced Gene-pool Optimal Mixing Evolutionary Algorithm (GOMEA) family has been shown to be capable of excellent performance on academic benchmark problems, outperforming other state-of-the-art EAs, especially when efficient partial evaluations are possible. This holds true also for the latest extension, the Multi-Objective Real-Valued GOMEA (MO-RV-GOMEA). In this paper, we apply MO-RV-GOMEA to the real-world multi-objective optimization problem of catheter placement in High-Dose-Rate (HDR) brachytherapy for prostate cancer, a problem that is non-trivial to solve and has high real-world importance and relevance. Due to the underlying geometric structure of the real-valued variables, partial evaluations can be performed, allowing MO-RV-GOMEA to exploit this structure. The performance of MO-RV-GOMEA is tested on three real-world patient cases and compared to a recent state-of-the-art mixed-integer EA that is aimed at a restricted version of the problem. We find that with MO-RV-GOMEA better solutions can be found much faster, making our proposed approach much more realistic to be used in clinical practice, and enabling new insights into both catheter placement for prostate brachytherapy and on objectives used for automated treatment planning. First results indicate that richer problem models are needed to better match real-world clinical preferences.
- Published
- 2018
- Full Text
- View/download PDF
22. Application and benchmarking of multi-objective evolutionary algorithms on high-dose-rate brachytherapy planning for prostate cancer treatment
- Author
-
Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Bel, A. (Arjan), Niatsetski, Y. (Yury), Bosman, P.A.N. (Peter), Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Bel, A. (Arjan), Niatsetski, Y. (Yury), and Bosman, P.A.N. (Peter)
- Abstract
High-Dose-Rate (HDR) brachytherapy (BT) treatment planning involves determining an appropriate schedule of a radiation source moving through a patient's body such that target volumes are irradiated with the planning-aim dose as much as possible while healthy tissues (i.e., organs at risk) should not be irradiated more than certain thresholds. Such movement of a radiation source can be defined by so-called dwell times at hundreds of potential dwell positions, which must be configured to satisfy a clinical protocol of multiple different treatment criteria within a strictly-limited time frame of not more than one hour. In this article, we propose a bi-objective optimization model that intuitively encapsulates in two objectives the complicated high-dimensional multi-criteria nature of the BT treatment planning problem. The resulting Pareto-optimal fronts exhibit possible trade-offs between the coverage of target volumes and the sparing of organs at risk, thereby intuitively facilitating the decision-making process of treatment planners when creating a clinically-acceptable plan.We employ real medical data for conducting experiments and benchmark four different Multi-Objective Evolutionary Algorithms (MOEAs) on solving our problem: the Non-dominated Sorting Genetic Algorithm II (NSGA-II), the Multi-Objective Evolutionary Algorithm based on Decomposition (MOEA/D), the Multi-objective Adapted Maximum-Likelihood Gaussian Model Iterated Density-Estimation Evolutionary Algorithm (MAMaLGaM), and the recently-introduced Multi-Objective Real-Valued Gene-pool Optimal Mixing Evolutionary Algorithm (MO-RV-GOMEA). The variation operator that is specific to MO-RV-GOMEA enables performing partial evaluations to efficiently calculate objective values of offspring solutions without incurring the cost of fully recomputing the radiation dose distributions for new treatment plans. Experimental results show that MO-RV-GOMEA is the best performing MOEA that effectively exploits dependencies
- Published
- 2018
- Full Text
- View/download PDF
23. Beam characterisation of the 1.5 T MRI-linac
- Author
-
Woodings, S J, primary, Bluemink, J J, additional, de Vries, J H W, additional, Niatsetski, Y, additional, van Veelen, B, additional, Schillings, J, additional, Kok, J G M, additional, Wolthaus, J W H, additional, Hackett, S L, additional, van Asselen, B, additional, van Zijp, H M, additional, Pencea, S, additional, Roberts, D A, additional, Lagendijk, J J W, additional, and Raaymakers, B W, additional
- Published
- 2018
- Full Text
- View/download PDF
24. EP-2236: Sensitivity of dose-volume indices to organ reconstruction settings in HDR prostate brachytherapy
- Author
-
Van der Meer, M.C., primary, Bosman, P.A.N., additional, Pieters, B.R., additional, Niatsetski, Y., additional, Alderliesten, T., additional, and Bel, A., additional
- Published
- 2018
- Full Text
- View/download PDF
25. PV-0140: Beam characterization of the Elekta MRI-linac for the first clinical trial
- Author
-
Woodings, S., primary, Bluemink, J.J., additional, De Vries, J.H.W., additional, Niatsetski, Y., additional, Van Veelen, B., additional, Schillings, J., additional, Kok, J.G.M., additional, Wolthaus, J.W.H., additional, Hackett, S.L., additional, Van Asselen, B., additional, Van Zijp, H.M., additional, Pencea, S., additional, Roberts, D.A., additional, Lagendijk, J.J.W., additional, and Raaymakers, B.W., additional
- Published
- 2018
- Full Text
- View/download PDF
26. PV-0256: Fast and insightful bi-objective HDR prostate brachytherapy planning
- Author
-
Luong, N.H., primary, Alderliesten, T., additional, Pieters, B.R., additional, Bel, A., additional, Niatsetski, Y., additional, and Bosman, P.A.N., additional
- Published
- 2018
- Full Text
- View/download PDF
27. Efficient, effective, and insightful tackling of the high-dose-rate brachytherapy treatment planning problem for prostate cancer using evolutionary multi-objective optimization algorithms
- Author
-
Luong, N.H. (Hoang), Bouter, P.A. (Anton), Meer, M.C. (Marjolein) van der, Niatsetski, Y. (Yury), Witteveen, C. (Cees), Bel, A. (Arjan), Alderliesten, T. (Tanja), Bosman, P.A.N. (Peter), Luong, N.H. (Hoang), Bouter, P.A. (Anton), Meer, M.C. (Marjolein) van der, Niatsetski, Y. (Yury), Witteveen, C. (Cees), Bel, A. (Arjan), Alderliesten, T. (Tanja), and Bosman, P.A.N. (Peter)
- Abstract
We address the problemof high-dose-rate brachytherapy treatment planning for prostate cancer. The problem involves determining a treatment plan consisting of the so-called dwell times that a radiation source resides at different positions inside the patient such that the prostate volume and the seminal vesicles are covered by the prescribed radiation dose level as much as possiblewhile the organs at risk, e.g., bladder, rectum, and urethra, are irradiated as little as possible. The problem is highly constrained, following clinical requirements for radiation dose distributionwhile the planning process for treatment planners to design a clinically-Acceptable treatment plan is strictly time-limited. In this paper, we propose that the problem can be formulated as a bi-objective optimization problem that intuitively describes trade-offs between target volumes to be radiated and organs to be spared. We solve this problem with the recently-introduced Multi-Objective Real-Valued Genepool Optimal Mixing Evolutionary Algorithm (MO-RV-GOMEA), which is a promising MOEA that is able to effectively exploit dependencies between problem variables to tackle complicated problems in the continuous domain. MO-RV-GOMEA also has the capability to perform partial evaluations if problem structures allow local variations in existing solutions to be efficiently computed, substantially accelerating the overall optimization performance. Experiments on real medical data and comparison with state-of-Theart MOEAs confirm our claims.
- Published
- 2017
- Full Text
- View/download PDF
28. Exploring trade-offs between target coverage, healthy tissue sparing, and the placement of catheters in HDR brachytherapy for prostate cancer using a novel multi-objective model-based mixed-integer evolutionary algorithm
- Author
-
Sadowski, K.L. (Krzysztof), Meer, M.C. (Marjolein) van der, Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Thierens, D. (Dirk), Laarse, R. (Rob) van der, Niatsetski, Y. (Yury), Bel, A. (Arjan), Bosman, P.A.N. (Peter), Sadowski, K.L. (Krzysztof), Meer, M.C. (Marjolein) van der, Luong, N.H. (Hoang), Alderliesten, T. (Tanja), Thierens, D. (Dirk), Laarse, R. (Rob) van der, Niatsetski, Y. (Yury), Bel, A. (Arjan), and Bosman, P.A.N. (Peter)
- Published
- 2017
- Full Text
- View/download PDF
29. Design and characterization of a new high-dose-rate brachytherapy Valencia applicator for larger skin lesions
- Author
-
Candela-Juan, C, Niatsetski, Y, van der Laarse, R, Granero, D, Ballester, F, Perez-Calatayud, J, and Vijande, J
- Subjects
HDR brachytherapy ,skin applicator ,Valencia applicator ,dosimetry ,Monte Carlo - Abstract
Purpose: The aims of this study were (i) to design a new high-dose-rate (HDR) brachytherapy applicator for treating surface lesions with planning target volumes larger than 3 cm in diameter and up to 5 cm in size, using the microSelectron-HDR or Flexitron afterloader (Elekta Brachytherapy) with a Ir-192 source; (ii) to calculate by means of the Monte Carlo (MC) method the dose distribution for the new applicator when it is placed against a water phantom; and (iii) to validate experimentally the dose distributions in water. Methods: The PENELOPE2008 MC code was used to optimize dwell positions and dwell times. Next, the dose distribution in a water phantom and the leakage dose distribution around the applicator were calculated. Finally, MC data were validated experimentally for a 192Ir mHDR-v2 source by measuring (i) dose distributions with radiochromic EBT3 films (ISP); (ii) percentage depth-dose (PDD) curve with the parallel-plate ionization chamber Advanced Markus (PTW); and (iii) absolute dose rate with EBT3 films and the PinPoint T31016 (PTW) ionization chamber. Results: The new applicator is made of tungsten alloy (Densimet) and consists of a set of interchangeable collimators. Three catheters are used to allocate the source at prefixed dwell positions with preset weights to produce a homogenous dose distribution at the typical prescription depth of 3 mm in water. The same plan is used for all available collimators. PDD, absolute dose rate per unit of air kerma strength, and off-axis profiles in a cylindrical water phantom are reported. These data can be used for treatment planning. Leakage around the applicator was also scored. The dose distributions, PDD, and absolute dose rate calculated agree within experimental uncertainties with the doses measured: differences of MC data with chamber measurements are up to 0.8% and with radiochromic films are up to 3.5%. Conclusions: The new applicator and the dosimetric data provided here will be a valuable tool in clinical practice, making treatment of large skin lesions simpler, faster, and safer. Also the dose to surrounding healthy tissues is minimal. (C) 2016 American Association of Physicists in Medicine.
- Published
- 2016
30. Response to 'Comment on 'Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry'' [Med. Phys. 42, 4954-4964 (2015)]
- Author
-
Candela-Juan C, Vijande J, Garcia-Martinez T, Niatsetski Y, Nauta G, Schuurman J, Ouhib Z, Ballester F, and Perez-Calatayud J
- Subjects
Brachytherapy ,Radiometry - Published
- 2016
31. PV-0188: Improved class solutions for prostate brachytherapy planning via evolutionary machine learning
- Author
-
Maree, S.C., primary, Bosman, P.A.N., additional, Niatsetski, Y., additional, Koedooder, C., additional, Van Wieringen, N., additional, Bel, A., additional, Pieters, B.R., additional, and Alderliesten, T., additional
- Published
- 2017
- Full Text
- View/download PDF
32. Commissioning and periodic tests of the Esteya (R) electronic brachytherapy system
- Author
-
Candela-Juan, C, Niatsetski, Y, Ouhib, Z, Ballester, F, Vijande, J, and Perez-Calatayud, J
- Subjects
Esteya ,electronic brachytherapy ,commissioning ,quality assurance - Abstract
A new electronic brachytherapy unit from Elekta, called Esteya(R), has recently been introduced to the market. As a part of the standards in radiation oncology, an acceptance testing and commissioning must be performed prior to treatment of the first patient. In addition, a quality assurance program should be implemented. A complete commissioning and periodic testing of the Esteya(R) device using the American Association of Physicists in Medicine (AAPM), Groupe Europeen de Curietherapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO) guidelines for linacs and brachytherapy units as well as our personal experience is described in this paper. In addition to the methodology, recommendations on equipment required for each test are provided, taking into consideration their availability and traceability of the detectors. Finally, tolerance levels for all the tests are provided, and a specific frequency for each test is suggested.
- Published
- 2015
33. Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry
- Author
-
Candela-Juan, C, Vijande, J, Garcia-Martinez, T, Niatsetski, Y, Nauta, G, Schuurman, J, Ouhib, Z, Ballester, F, and Perez-Calatayud, J
- Subjects
dosimetry ,electronic brachytherapy ,surface applicators ,uncertainty ,x-ray beams - Abstract
Purpose: A surface electronic brachytherapy (EBT) device is in fact an x-ray source collimated with specific applicators. Low-energy (
- Published
- 2015
34. Review of clinical brachytherapy uncertainties: Analysis guidelines of GEC-ESTRO and the AAPM
- Author
-
Kirisits, C. Rivard, M.J. Baltas, D. Ballester, F. De Brabandere, M. Van Der Laarse, R. Niatsetski, Y. Papagiannis, P. Hellebust, T.P. Perez-Calatayud, J. Tanderup, K. Venselaar, J.L.M. Siebert, F.-A.
- Abstract
Background and purpose A substantial reduction of uncertainties in clinical brachytherapy should result in improved outcome in terms of increased local control and reduced side effects. Types of uncertainties have to be identified, grouped, and quantified. Methods A detailed literature review was performed to identify uncertainty components and their relative importance to the combined overall uncertainty. Results Very few components (e.g., source strength and afterloader timer) are independent of clinical disease site and location of administered dose. While the influence of medium on dose calculation can be substantial for low energy sources or non-deeply seated implants, the influence of medium is of minor importance for high-energy sources in the pelvic region the level of uncertainties due to target, organ, applicator, and/or source movement in relation to the geometry assumed for treatment planning is highly dependent on fractionation and the level of image guided adaptive treatment. Most studies to date report the results in a manner that allows no direct reproduction and further comparison with other studies. Often, no distinction is made between variations, uncertainties, and errors or mistakes the literature review facilitated the drafting of recommendations for uniform uncertainty reporting in clinical BT, which are also provided the recommended comprehensive uncertainty investigations are key to obtain a general impression of uncertainties, and may help to identify elements of the brachytherapy treatment process that need improvement in terms of diminishing their dosimetric uncertainties. It is recommended to present data on the analyzed parameters (distance shifts, volume changes, source or applicator position, etc.), and also their influence on absorbed dose for clinically-relevant dose parameters (e.g., target parameters such as D90 or OAR doses). Publications on brachytherapy should include a statement of total dose uncertainty for the entire treatment course, taking into account the fractionation schedule and level of image guidance for adaptation. Conclusions This report on brachytherapy clinical uncertainties represents a working project developed by the Brachytherapy Physics Quality Assurances System (BRAPHYQS) subcommittee to the Physics Committee within GEC-ESTRO. Further, this report has been reviewed and approved by the American Association of Physicists in Medicine. © 2013 Elsevier Ireland Ltd. All rights reserved.
- Published
- 2014
35. EP-1992: Design and characterization of a new HDR brachytherapy Valencia applicator for larger skin lesions
- Author
-
Vijande, J., primary, Candela-Juan, C., additional, Niatsetski, Y., additional, Van der Laarse, R., additional, Granero, D., additional, Ballester, F., additional, and Perez-calatayud, J., additional
- Published
- 2016
- Full Text
- View/download PDF
36. MR and CT Based Treatment Planning for mTHPC Mediated Interstitial Photodynamic Therapy of Head and Neck Cancer: Description of the Method
- Author
-
Karakullukcu, B, Veen, Robert, Aans, JB, Hamming-Vrieze, O, Navran, A, Teertstra, HJ, van den Boom, F, Niatsetski, Y, Sterenborg, Dick, Tan, IB, and Radiotherapy
- Subjects
SDG 3 - Good Health and Well-being - Abstract
Background and ObjectiveInterstitial photodynamic therapy is a potentially important tool in the management of voluminous or deep-seated recurrent head and neck cancers. Study Design/MethodsThe described treatment algorithm in this manuscript consists of the treatment simulation, implantation of light sources, verification, modification of the treatment plan if necessary, and illumination. The tumor is delineated on imaging sections (CT, MRI, and/or PET/CT) and the treatment is simulated by virtually introducing light sources to the tumor volume on specially modified brachytherapy software. This enables us to determine if the treatment is technically feasible, a ResultsThis method has the potential to help with identifying iPDT feasible patients by simulating before the actual treatment. The suboptimal placement of light sources can be identified and corrected. The simulations were documented and saved for subsequent evaluation of the technique. ConclusionThe proposed technique can help standardize and document iPDT. Lasers Surg. Med. 45:517-523, 2013. (c) 2013 Wiley Periodicals, Inc.
- Published
- 2013
37. SU‐E‐T‐720: Surface Electronic Brachytherapy Dosimetry: Comparison and Uncertainty Evaluation of Different Calibration Protocols and Ionization Chambers
- Author
-
Candela‐Juan, C, primary, Garcia‐Martinez, T, additional, Niatsetski, Y, additional, Schuurman, J, additional, Nauta, G, additional, Vijande, J, additional, Ouhib, Z, additional, Ballester, F, additional, and Perez‐Calatayud, J, additional
- Published
- 2015
- Full Text
- View/download PDF
38. PD-0186: Dosimetric evaluation of the electronic brachytherapy system Esteya
- Author
-
Perez-Calatayud, J., primary, Candela-Juan, C., additional, Vijande, J., additional, Ouhib, Z., additional, García-Martínez, T., additional, Niatsetski, Y., additional, Nauta, G., additional, Schuurman, J., additional, and Ballester, F., additional
- Published
- 2015
- Full Text
- View/download PDF
39. Comment on "Comparison and uncertainty evaluation of different calibration protocols and ionization chambers for low-energy surface brachytherapy dosimetry".
- Author
-
Fulkerson, Regina, Candela-Juana, C., Vijande, J., García-Martínez, T., Niatsetski, Y., Nauta, G., Schuurman, J., Ouhib, Z., Ballester, F., and Perez-Calatayud, J.
- Subjects
IONIZATION chambers ,RADIOISOTOPE brachytherapy ,RADIATION dosimetry ,CALIBRATION ,MEDICAL physics - Published
- 2016
- Full Text
- View/download PDF
40. 695 poster SOURCE PATH MEASUREMENTS FOR RING APPLICATORS
- Author
-
Niatsetski, Y., primary, Fekkes, S., additional, and Vreeken, H., additional
- Published
- 2011
- Full Text
- View/download PDF
41. A Belarusian protocol for the dosimetry of high-energy photon beams
- Author
-
Niatsetski, Y., primary and Tarutin, I., additional
- Published
- 1997
- Full Text
- View/download PDF
42. Neural network-assisted automated image registration for MRI-guided adaptive brachytherapy in cervical cancer.
- Author
-
Ecker S, Zimmermann L, Heilemann G, Niatsetski Y, Schmid M, Sturdza AE, Knoth J, Kirisits C, and Nesvacil N
- Subjects
- Female, Humans, Retrospective Studies, Magnetic Resonance Imaging methods, Neural Networks, Computer, Image Processing, Computer-Assisted methods, Brachytherapy methods, Uterine Cervical Neoplasms diagnostic imaging, Uterine Cervical Neoplasms radiotherapy
- Abstract
Purpose: In image-guided adaptive brachytherapy (IGABT) a quantitative evaluation of the dosimetric changes between fractions due to anatomical variations, can be implemented via rigid registration of images from subsequent fractions based on the applicator as a reference structure. With available treatment planning systems (TPS), this is a manual and time-consuming process. The aim of this retrospective study was to automate this process. A neural network (NN) was trained to predict the applicator structure from MR images. The resulting segmentation was used to automatically register MR-volumes., Material and Methods: DICOM images and plans of 56 patients treated for cervical cancer with high dose-rate (HDR) brachytherapy were used in the study. A 2D and a 3D NN were trained to segment applicator structures on clinical T2-weighted MRI datasets. Different rigid registration algorithms were investigated and compared. To evaluate a fully automatic registration workflow, the NN-predicted applicator segmentations (AS) were used for rigid image registration with the best performing algorithm. The DICE coefficient and mean distance error between dwell positions (MDE) were used to evaluate segmentation and registration performance., Results: The mean DICE coefficient for the predicted AS was 0.70 ± 0.07 and 0.58 ± 0.04 for the 3D NN and 2D NN, respectively. Registration algorithms achieved MDE errors from 8.1 ± 3.7 mm (worst) to 0.7 ± 0.5 mm (best), using ground-truth AS. Using the predicted AS from the 3D NN together with the best registration algorithm, an MDE of 2.7 ± 1.4 mm was achieved., Conclusion: Using a combination of deep learning models and state of the art image registration techniques has been demonstrated to be a promising solution for automatic image registration in IGABT. In combination with auto-contouring of organs at risk, the auto-registration workflow from this study could become part of an online-dosimetric interfraction evaluation workflow in the future., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Department of Radiation Oncology at Medical University of Vienna receives financial and/or equipment support for research and educational purposes from Elekta AB. CK, AS and NN received travel support and honoraria for educational activities from Elekta AB. YN is an employee of Elekta AB.], (Copyright © 2022. Published by Elsevier GmbH.)
- Published
- 2022
- Full Text
- View/download PDF
43. A Monte Carlo study of the relative biological effectiveness in surface brachytherapy.
- Author
-
Valdes-Cortez C, Niatsetski Y, Perez-Calatayud J, Ballester F, and Vijande J
- Subjects
- DNA Damage radiation effects, Electronics, Humans, Monte Carlo Method, Radioisotopes, Brachytherapy adverse effects, Brachytherapy methods, Relative Biological Effectiveness
- Abstract
Purpose: This work aims to simulate clustered DNA damage from ionizing radiation and estimate the relative biological effectiveness (RBE) for radionuclide (rBT)- and electronic (eBT)-based surface brachytherapy through a hybrid Monte Carlo (MC) approach, using realistic models of the sources and applicators., Methods: Damage from ionizing radiation has been studied using the Monte Carlo Damage Simulation algorithm using as input the primary electron fluence simulated using a state-of-the-art MC code, PENELOPE-2018. Two
192 Ir rBT applicators, Valencia and Leipzig, one60 Co source with a Freiburg Flap applicator (reference source), and two eBT systems, Esteya and INTRABEAM, have been included in this study implementing full realizations of their geometries as disclosed by the manufacturer. The role played by filtration and tube kilovoltage has also been addressed., Results: For rBT, an RBE value of about 1.01 has been found for the applicators and phantoms considered. In the case of eBT, RBE values for the Esteya system show an almost constant RBE value of about 1.06 for all depths and materials. For INTRABEAM, variations in the range of 1.12-1.06 are reported depending on phantom composition and depth. Modifications in the Esteya system, filtration, and tube kilovoltage give rise to variations in the same range., Conclusions: Current clinical practice does not incorporate biological effects in surface brachytherapy. Therefore, the same absorbed dose is administered to the patients independently on the particularities of the rBT or eBT system considered. The almost constant RBE values reported for rBT support that assumption regardless of the details of the patient geometry, the presence of a flattening filter in the applicator design, or even significant modifications in the photon energy spectra above 300 keV. That is not the case for eBT, where a clear dependence on the eBT system and the characteristics of the patient geometry are reported. A complete study specific for each eBT system, including detailed applicator characteristics (size, shape, filtering, among others) and common anatomical locations, should be performed before adopting an existing RBE value., (© 2022 American Association of Physicists in Medicine.)- Published
- 2022
- Full Text
- View/download PDF
44. Robust optimization for HDR prostate brachytherapy applied to organ reconstruction uncertainty.
- Author
-
van der Meer MC, Bosman PAN, Niatsetski Y, Alderliesten T, Pieters BR, and Bel A
- Subjects
- Algorithms, Humans, Male, Radiometry, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Uncertainty, Brachytherapy methods, Image Processing, Computer-Assisted, Prostatic Neoplasms diagnostic imaging, Prostatic Neoplasms radiotherapy, Radiation Dosage
- Abstract
Purpose: Recently, we introduced a bi-objective optimization approach based on dose-volume indices to automatically create clinically good HDR prostate brachytherapy plans. To calculate dose-volume indices, a reconstruction algorithm is used to determine the 3D organ shape from 2D contours, inevitably containing settings that influence the result. We augment the optimization approach to quickly find plans that are robust to differences in 3D reconstruction., Methods: Studied reconstruction settings were: interpolation between delineated organ contours, overlap between contours, and organ shape at the top and bottom contour. Two options for each setting yields 8 possible 3D organ reconstructions per patient, over which the robust model defines minimax optimization. For the original model, settings were based on our treatment planning system. Both models were tested on data of 26 patients and compared by re-evaluating selected optimized plans both in the original model (1 organ reconstruction, the difference determines the cost), and in the robust model (8 organ reconstructions, the difference determines the benefit)., Results: Robust optimization increased the run time from 3 to 6 min. The median cost for robust optimization as observed in the original model was -0.25% in the dose-volume indices with a range of [-0.01%, -1.03%]. The median benefit of robust optimization as observed in the robust model was 0.93% with a range of [0.19%, 4.16%]. For 4 patients, selected plans that appeared good when optimized in the original model, violated the clinical protocol with more than 1% when considering different settings. This was not the case for robustly optimized plans., Conclusions: Plans of high quality, irrespective of 3D organ reconstruction settings, can be obtained using our robust optimization approach. With its limited effect on total runtime, our approach therefore offers a way to account for dosimetry uncertainties that result from choices in organ reconstruction settings that is viable in clinical practice.
- Published
- 2021
- Full Text
- View/download PDF
45. Depth-dose measurement corrections for the surface electronic brachytherapy beams of an Esteya ® unit: a Monte Carlo study.
- Author
-
Valdes-Cortez C, Ballester F, Vijande J, Gimenez V, Gimenez-Alventosa V, Perez-Calatayud J, Niatsetski Y, and Andreo P
- Subjects
- Electronics, Monte Carlo Method, Radiometry methods, X-Rays, Brachytherapy methods
- Abstract
Three different correction factors for measurements with the parallel-plate ionization chamber PTW T34013 on the Esteya electronic brachytherapy unit have been investigated. This chamber type is recommended by AAPM TG-253 for depth-dose measurements in the 69.5 kV x-ray beam generated by the Esteya unit.Monte Carlo simulations using the PENELOPE-2018 system were performed to determine the absorbed dose deposited in water and in the chamber sensitive volume at different depths with a Type A uncertainty smaller than 0.1%. Chamber-to-chamber differences have been explored performing measurements using three different chambers. The range of conical applicators available, from 10 to 30 mm in diameter, has been explored.Using a depth-independent global chamber perturbation correction factor without a shift of the effective point of measurement yielded differences between the absorbed dose to water and the corrected absorbed dose in the sensitive volume of the chamber of up to 1% and 0.6% for the 10 mm and 30 mm applicators, respectively. Calculations using a depth-dependent perturbation factor, including or excluding a shift of the effective point of measurement, resulted in depth-dose differences of about ± 0.5% or less for both applicators. The smallest depth-dose differences were obtained when a shift of the effective point of measurement was implemented, being displaced 0.4 mm towards the center of the sensitive volume of the chamber. The correction factors were obtained with combined uncertainties of 0.4% ( k = 2). Uncertainties due to chamber-to-chamber differences are found to be lower than 2%.The results emphasize the relevance of carrying out detailed Monte Carlo studies for each electronic brachytherapy device and ionization chamber used for its dosimetry., (Creative Commons Attribution license.)
- Published
- 2020
- Full Text
- View/download PDF
46. Bi-objective optimization of catheter positions for high-dose-rate prostate brachytherapy.
- Author
-
van der Meer MC, Bosman PAN, Niatsetski Y, Alderliesten T, van Wieringen N, Pieters BR, and Bel A
- Subjects
- Catheters, Humans, Male, Radiotherapy Dosage, Radiotherapy Planning, Computer-Assisted, Retrospective Studies, Brachytherapy, Prostatic Neoplasms radiotherapy
- Abstract
Purpose: Bi-objective simultaneous optimization of catheter positions and dwell times for high-dose-rate (HDR) prostate brachytherapy, based directly on dose-volume indices, has shown promising results. However, optimization with the state-of-the-art evolutionary algorithm MO-RV-GOMEA so far required several hours of runtime, and resulting catheter positions were not always clinically feasible. The aim of this study is to extend the optimization model and apply GPU parallelization to achieve clinically acceptable computation times. The resulting optimization procedure is compared with a previously introduced method based solely on geometric criteria, the adapted Centroidal Voronoi Tessellations (CVT) algorithm., Methods: Bi-objective simultaneous optimization was performed with a GPU-parallelized version of MO-RV-GOMEA. This optimization of catheter positions and dwell times was retrospectively applied to the data of 26 patients previously treated with HDR prostate brachytherapy for 8-16 catheters (steps of 2). Optimization of catheter positions using CVT was performed in seconds, after which optimization of only the dwell times using MO-RV-GOMEA was performed in 1 min., Results: Simultaneous optimization of catheter positions and dwell times using MO-RV-GOMEA was performed in 5 min. For 16 down to 8 catheters (steps of 2), MO-RV-GOMEA found plans satisfying the planning-aims for 20, 20, 18, 14, and 11 out of the 26 patients, respectively. CVT achieved this for 19, 17, 13, 9, and 2 patients, respectively. The P-value for the difference between MO-RV-GOMEA and CVT was 0.023 for 16 catheters, 0.005 for 14 catheters, and <0.001 for 12, 10, and 8 catheters., Conclusions: With bi-objective simultaneous optimization on a GPU, high-quality catheter positions can now be obtained within 5 min, which is clinically acceptable, but slower than CVT. For 16 catheters, the difference between MO-RV-GOMEA and CVT is clinically irrelevant. For 14 catheters and less, MO-RV-GOMEA outperforms CVT in finding plans satisfying all planning-aims., (© 2020 The Authors. Medical Physics published by Wiley Periodicals LLC on behalf of American Association of Physicists in Medicine.)
- Published
- 2020
- Full Text
- View/download PDF
47. GPU-accelerated bi-objective treatment planning for prostate high-dose-rate brachytherapy.
- Author
-
Bouter A, Alderliesten T, Pieters BR, Bel A, Niatsetski Y, and Bosman PAN
- Subjects
- Algorithms, Humans, Male, Radiotherapy Dosage, Brachytherapy, Computer Graphics, Prostatic Neoplasms radiotherapy, Radiation Dosage, Radiotherapy Planning, Computer-Assisted methods
- Abstract
Purpose: The purpose of this study is to improve upon a recently introduced bi-objective treatment planning method for prostate high-dose-rate (HDR) brachytherapy (BT), both in terms of resulting plan quality and runtime requirements, to the extent that its execution time is clinically acceptable., Methods: Bi-objective treatment planning is done using a state-of-the-art multiobjective evolutionary algorithm, which produces a large number of potential treatment plans with different trade-offs between coverage of the target volumes and sparing organs at risk. A graphics processing unit (GPU) is used for large-scale parallelization of dose calculations and the calculation of the dose-volume (DV) indices of potential treatment plans. Moreover, the objectives of the previously used bi-objective optimization model are modified to produce better results., Results: We applied the GPU-accelerated bi-objective treatment planning method to a set of 18 patients, resulting in a set containing a few hundred potential treatment plans with different trade-offs for each of these patients. Due to accelerations introduced in this article, results previously achieved after 1 hour are now achieved within 30 seconds of optimization. We found plans satisfying the clinical protocol for 15 of 18 patients, whereas this was the case for only 4 of 18 clinical plans. Higher quality treatment plans are obtained when the accuracy of DV index calculation is increased using more dose calculation points, requiring still no more than 3 minutes of optimization for 100 000 points., Conclusions: Large sets of high-quality treatment plans that trade-off coverage and sparing are now achievable within 30 seconds, due to the GPU-acceleration of a previously introduced bi-objective treatment planning method for prostate HDR brachytherapy. Higher quality plans can be achieved when optimizing for 3 minutes, which we still consider to be clinically acceptable. This allows for more insightful treatment plan selection in a clinical setting., (© 2019 American Association of Physicists in Medicine.)
- Published
- 2019
- Full Text
- View/download PDF
48. GEC-ESTRO ACROP recommendations on calibration and traceability of LE-LDR photon-emitting brachytherapy sources at the hospital level.
- Author
-
Perez-Calatayud J, Ballester F, Carlsson Tedgren Å, Rijnders A, Rivard MJ, Andrássy M, Niatsetski Y, Schneider T, and Siebert FA
- Subjects
- Calibration, Hospitals, Humans, Radiotherapy Dosage, Brachytherapy methods, Photons therapeutic use
- Abstract
Prostate brachytherapy treatment using permanent implantation of low-energy (LE) low-dose rate (LDR) sources is successfully and widely applied in Europe. In addition, seeds are used in other tumour sites, such as ophthalmic tumours, implanted temporarily. The calibration issues for LE-LDR photon emitting sources are specific and different from other sources used in brachytherapy. In this report, the BRAPHYQS (BRAchytherapy PHYsics Quality assurance System) working group of GEC-ESTRO, has developed the present recommendations to assure harmonized and high-quality seed calibration in European clinics. There are practical aspects for which a clarification/procedure is needed, including aspects not specifically accounted for in currently existing AAPM and ESTRO societal recommendations. The aim of this report has been to provide a European wide standard in LE-LDR source calibration at end-user level, in order to keep brachytherapy treatments with high safety and quality levels. The recommendations herein reflect the guidance to the ESTRO brachytherapy users and describe the procedures in a clinic or hospital to ensure the correct calibration of LE-LDR seeds., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2019
- Full Text
- View/download PDF
49. Sensitivity of dose-volume indices to computation settings in high-dose-rate prostate brachytherapy treatment plan evaluation.
- Author
-
van der Meer MC, Bosman PAN, Pieters BR, Niatsetski Y, van Wieringen N, Alderliesten T, and Bel A
- Subjects
- Aged, Aged, 80 and over, Humans, Male, Middle Aged, Prognosis, Radiometry methods, Radiotherapy Dosage, Software, Algorithms, Brachytherapy, Organs at Risk radiation effects, Prostatic Neoplasms radiotherapy, Radiotherapy Planning, Computer-Assisted methods
- Abstract
Purpose: To investigate the variation in computed dose-volume (DV) indices for high-dose-rate (HDR) prostate brachytherapy that can result from typical differences in computation settings in treatment planning systems (TPSs)., Methods: Five factors were taken into account: number of dose-calculation points, radioactive source description, interpolation between delineated contours, intersections between delineated organ contours, and organ shape at the top and bottom contour using either full or partial slice thickness. Using in-house developed software, the DV indices of the treatment plans of 26 patients were calculated with different settings, and compared to a baseline setting that closely followed the default settings of the TPS used in our medical center. Studied organs were prostate and seminal vesicles, denoted as targets, and bladder, rectum, and urethra, denoted as organs at risk (OARs), which were delineated on MRI scans with a 3.3 mm slice thickness., Results: When sampling a fixed number of points in each organ, in order to achieve a width of the 95% confidence interval over all patients of the DV indices of 1% or less, only 32,000 points had to be sampled per target, but 256,000 points had to be sampled per OAR. For the remaining factors, DV indices changed up to 0.4% for rectum, 1.3% for urethra, and 2.6% for prostate. DV indices of the bladder changed especially if the high-dose-region was (partly) located at the most caudal contour, up to 8.5%, and DV indices of the vesicles changed especially if there were few delineated contours, up to 9.8%, both due to the use of full slice thickness for the top and bottom contour., Conclusions: The values of DV indices used in prostate HDR brachytherapy treatment planning are influenced by the computation settings in a TPS, especially at the most caudal part of the bladder, as well as in the seminal vesicles., (© 2019 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.)
- Published
- 2019
- Full Text
- View/download PDF
50. A Monte Carlo-based dosimetric characterization of Esteya ® , an electronic surface brachytherapy unit.
- Author
-
Valdes-Cortez C, Niatsetski Y, Perez-Calatayud J, Ballester F, and Vijande J
- Subjects
- Photons, Radiometry, Uncertainty, Brachytherapy, Monte Carlo Method
- Abstract
Purpose: The purpose of this work is threefold: First, to obtain the phase space of an electronic brachytherapy (eBT) system designed for surface skin treatments. Second, to explore the use of some efficiency enhancing (EFEN) strategies in the determination of the phase space. Third, to use the phase space previously obtained to perform a dosimetric characterization of the Esteya eBT system., Methods: The Monte Carlo study of the 69.5 kVp x-ray beam of the Esteya
® unit (Elekta Brachytherapy, Veenendaal, The Netherlands) was performed with PENELOPE2014. The EFEN strategies included the use of variance reduction techniques and mixed Class II simulations, where transport parameters were fine-tuned. Four source models were studied varying the most relevant parameters characterizing the electron beam impinging the target: the energy spectrum (mono-energetic or Gaussian shaped), and the electron distribution over the focal spot (uniform or Gaussian shaped). Phase spaces obtained were analyzed to detect differences in the calculated data due to the EFEN strategy or the source configuration. Depth dose curves and absorbed dose profiles were obtained for each source model and compared to experimental data previously published., Results: In our EFEN strategy, the interaction forcing variance reduction (VRIF) technique increases efficiency by a factor ~20. Tailoring the transport parameters values (C1 and C2) does not increase the efficiency in a significant way. Applying a universal cutoff energy EABS of 10 keV saves 84% of CPU time while showing negligible impact on the calculated results. Disabling the electron transport by imposing an electron energy cutoff of 70 keV (except for the target) saves an extra 8% (losing in the process 1.2% of the photons). The Gaussian energy source (FWHM = 10%, centered at the nominal kVp, homogeneous electron distribution) shows characteristic K-lines in its energy spectrum, not observed experimentally. The average photon energy using an ideal source (mono-energetic, homogeneous electron distribution) was 36.19 ± 0.09 keV, in agreement with the published measured data of 36.2 ± 0.2 keV. The use of a Gaussian-distributed electron source (mono-energetic) increases the penumbra by 50%, which is closer to the measurement results. The maximum discrepancy of the calculated percent depth dose with the corresponding measured values is 4.5% (at the phantom surface, less than 2% beyond 1 mm depth) and 5% (for the 80% of the field) in the dose profile. Our results agree with the findings published by other authors and are consistent within the expected Type A and B uncertainties., Conclusions: Our results agree with the published measurement results within the reported uncertainties. The observed differences in PDD, dose profiles, and photon spectrum come from three main sources of uncertainty: intermachine variations, measurements, and Monte Carlo calculations. It has been observed that a mono-energetic source with a Gaussian electron distribution over the focal spot is a suitable choice to reproduce the experimental data., (© 2018 American Association of Physicists in Medicine.)- Published
- 2019
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.