PURPOSE: Without a clear definition of an optimal treatment plan, no optimization model can be perfect. Therefore, instead of automatically finding a single “optimal” plan, finding multiple, yet... Show morePURPOSE: Without a clear definition of an optimal treatment plan, no optimization model can be perfect. Therefore, instead of automatically finding a single “optimal” plan, finding multiple, yet different near-optimal plans, can be an insightful approach to support radiation oncologists in finding the plan they are looking for. METHODS AND MATERIALS: BRIGHT is a flexible AI-based optimization method for brachytherapy treatment planning that has already been shown capable of finding high-quality plans that trade-off target volume coverage and healthy tissue sparing. We leverage the flexibility of BRIGHT to find plans with similar dose-volume criteria, yet different dose distributions. We further describe extensions that facilitate fast plan adaptation should planning aims need to be adjusted, and straightforwardly allow incorporating hospital-specific aims besides standard protocols. RESULTS: Results are obtained for prostate (n=12) and cervix brachytherapy (n=36). We demonstrate the possible differences in dose distribution for optimized plans with equal dosevolume criteria. We furthermore demonstrate that adding hospital-specific aims enables adhering to hospital-specific practice while still being able to automatically create cervix plans that more often satisfy the EMBRACE-II protocol than clinical practice. Finally, we illustrate the feasibility of fast plan adaptation. CONCLUSIONS: Methods such as BRIGHT enable new ways to construct high-quality treatment plans for brachytherapy while offering new insights by making explicit the options one has. In particular, it becomes possible to present to radiation oncologists a manageable set of alternative plans that, from an optimization perspective are equally good, yet differ in terms of coverage-sparing trade-offs and shape of the dose distribution Show less
Simple Summary: Hearing loss (HL) can be a side effect of paediatric cancer treatment and can be caused by chemotherapy but also local therapies such as radiotherapy and/or surgery of the head and... Show moreSimple Summary: Hearing loss (HL) can be a side effect of paediatric cancer treatment and can be caused by chemotherapy but also local therapies such as radiotherapy and/or surgery of the head and neck region. In this study, the frequency and patterns of HL were assessed in survivors of head and neck rhabdomyosarcoma (HNRMS). Our secondary aim was to look into the dose-effect relationship between radiotherapy dose on the cochlea and the presence of HL. Forty-nine survivors of HNRMS were included in this study, forty-two of them underwent audiological evaluation. HL was found in up to 19% of the survivors. Four survivors had low frequencies HL with normal hearing or milder HL in the higher frequencies. In our series, HL (>= Muenster 2b) was significantly associated with the maximum cochlear irradiation dose (p = 0.047). More research is needed on HL patterns in HNRMS survivors and on the radiotherapy dose-effect relationship. Purpose: The frequency and patterns of HL in a HNRMS survivor cohort were investigated. A dose-effect relationship between the dose to the cochlea and HL was explored. Methods: Dutch survivors treated for HNRMS between 1993 and 2017 with no relapse and at least two years after the end of treatment were eligible for inclusion. The survivors were evaluated for HL with pure-tone audiometry. HL was graded according to the Muenster, Common Terminology Criteria for Adverse Events (CTCAE) v4.03 and International Society for Paediatric Oncology (SIOP) classification. We defined deleterious HL as Muenster >= 2b, CTCAE >= 2, and SIOP >= 2. Mixed-effects logistic regression was used to search for the dose-effect relationship between the irradiation dose to the cochlea and the occurrence of HL. Results: Forty-two HNRMS survivors underwent pure-tone audiometry. The Muenster, CTCAE and SIOP classification showed that 19.0% (n = 8), 14.2% (n = 6) and 11.9% (n = 5) of survivors suffered from HL, respectively. A low-frequency HL pattern with normal hearing or milder hearing loss in the higher frequencies was seen in four survivors. The maximum cochlear irradiation dose was significantly associated with HL (>= Muenster 2b) (p = 0.047). In our series, HL (>= Muenster 2b) was especially observed when the maximum dose to the cochlea exceeded 19 Gy. Conclusion: HL occurred in up to 19% of survivors of HNRMS. More research is needed on HL patterns in HNRMS survivors and on radiotherapy dose-effect relationships. Show less
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... Show morePurpose. 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. Show less
Meer, M.C. van der; Bosman, P.A.N.; Niatsetski, Y.; Alderliesten, T.; Wieringen, N. van; Pieters, B.R.; Bel, A. 2020
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... Show morePurpose 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. TheP-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. Show less
Background/objectives To evaluate the management of conjunctival melanoma with local excision and adjuvant brachytherapy. Subjects/methods Data of all patients who received local excision and... Show moreBackground/objectives To evaluate the management of conjunctival melanoma with local excision and adjuvant brachytherapy. Subjects/methods Data of all patients who received local excision and adjuvant brachytherapy for conjunctival melanoma between 1999 and 2016 in a Dutch national referral centre were reviewed. A protocol with Sr-90 was used until 2012, a protocol with Ru-106 was used hereafter. Local recurrence, metastasis, survival, visual acuity and treatment complications were assessed. Results A total of 58 patients was identified: 32 patients were treated with Sr-90 and 26 with Ru-106. Mean follow-up time was 97.3 months (143.1 months after Sr-90, and 40.2 months after Ru-106). All lesions were epibulbar, the median tumour thickness was 0.9 mm. Local recurrence occurred in 13/58 cases (22%), with a 5-year recurrence rate of 21%. Local recurrence occurred equally often in both protocols, with 5-year recurrence rates of 19% (Sr-90) versus 23% (Ru-106) (p = 0.68). Metastasis developed in 3/58 cases (5%), with 2 cases after Sr-90, and 1 after Ru-106 (p = 1.00). The most reported complications were pain (29%), dry eyes (21%), symblepharon (9%), ptosis (12%) and cataract (9%). No severe corneal or scleral complications were observed. Median visual acuity was 1.00 pre-surgery, at the end of follow-up this was 1.00 (Sr-90) and 0.95 (Ru-106). Conclusion Local excision with adjuvant brachytherapy provides good tumour control with excellent visual outcome and mild side effects in patients with limited conjunctival melanoma. Results after Sr-90 or Ru-106 were comparable; a choice for either treatment may be based on experience of the clinician and availability of materials. Show less
Maree, S.C.; Bosman, P.A.N.; Wieringen, N. van; Niatsetski, Y.; Pieters, B.R.; Bel, A.; Alderliesten, T. 2020
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... Show moreWe 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-off curves for different inverse planning methods, their maximally achievable plan quality can be insightfully compared. Automatic parameter tuning furthermore allows to construct standard parameter sets (class solutions) representing different trade-offs in a principled way, which can be directly used in current clinical practice. In this work, we considered the inverse planning methods IPSA and HIPO. Thirty-nine previously treated prostate cancer patients were included. We compared automatic parameter tuning, random parameter sampling, and the maximally achievable plan quality obtained by directly optimizing the bi-objective planning model with the state-of-the-art optimization software GOMEA. We showed that for each patient, a set of plans with a wide range of trade-offs could be obtained using automatic parameter tuning for both IPSA and HIPO. By tuning HIPO, better trade-offs were obtained than by tuning IPSA. For most patients, automatic tuning of HIPO resulted in plans close to the maximally achievable plan quality obtained by optimizing the bi-objective planning model directly. Automatic parameter tuning was shown to improve plan quality significantly compared to random parameter sampling. Finally, from the automatically-tuned plans, three class solutions were successfully constructed representing different trade-offs. Show less
Witjes, J.A.; Babjuk, M.; Bellmunt, J.; Bruins, H.M.; Reijke, T.M. de; Santis, M. de; ... ; Horwich, A. 2020
Background: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.Objective: To... Show moreBackground: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.Objective: To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.Design: A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts prior to voting during a consensus conference.Setting: Online Delphi survey and consensus conference.Participants: The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.Outcome measurements and statistical analysis: Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), and 7-9 (agree). A priori (level 1) consensus was defined as >= 70% agreement and <= 15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).Results and limitations: Overall, 116 statements were included in the Delphi survey. Of these statements, 33 (28%) achieved level 1 consensus and 49 (42%) achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease, and the evolving role of checkpoint inhibitor therapy in metastatic disease.Conclusions: These consensus statements provide further guidance on controversial topics in advanced and variant bladder canceir management until a time when further evidence is available to guide our approach.Patient summary: This report summarises findings from an international, multistake-holder project organised by the EAU and ESMO. In this project, a steering committee identified areas of bladder cancer management where there is currently no good-quality evidence to guide treatment decisions. From this, they developed a series of proposed statements, 71 of which achieved consensus by a large group of experts in the field of bladder cancer. It is anticipated that these statements will provide further guidance to health care professionals and could help improve patient outcomes until a time when good-quality evidence is available. (C) 2019 European Society of Medical Oncology and European Association of Urology. Published by Elsevier B.V. All rights reserved. Show less
Horwich, A.; Babjuk, M.; Bellmunt, J.; Bruins, H.M.; Reijke, T.M. de; Santis, M. de; ... ; Witjes, J.A. 2019
Background: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.Objective: To... Show moreBackground: Although guidelines exist for advanced and variant bladder cancer management, evidence is limited/conflicting in some areas and the optimal approach remains controversial.Objective: To bring together a large multidisciplinary group of experts to develop consensus statements on controversial topics in bladder cancer management.Design: A steering committee compiled proposed statements regarding advanced and variant bladder cancer management which were assessed by 113 experts in a Delphi survey. Statements not reaching consensus were reviewed; those prioritised were revised by a panel of 45 experts before voting during a consensus conference.Setting: Online Delphi survey and consensus conference.Participants: The European Association of Urology (EAU), the European Society for Medical Oncology (ESMO), experts in bladder cancer management.Outcome measurements and statistical analysis: Statements were ranked by experts according to their level of agreement: 1-3 (disagree), 4-6 (equivocal), 7-9 (agree). A priori (level 1) consensus was defined as >= 70% agreement and <= 15% disagreement, or vice versa. In the Delphi survey, a second analysis was restricted to stakeholder group(s) considered to have adequate expertise relating to each statement (to achieve level 2 consensus).Results and limitations: Overall, 116 statements were included in the Delphi survey. Of these, 33 (28%) statements achieved level 1 consensus and 49 (42%) statements achieved level 1 or 2 consensus. At the consensus conference, 22 of 27 (81%) statements achieved consensus. These consensus statements provide further guidance across a broad range of topics, including the management of variant histologies, the role/limitations of prognostic biomarkers in clinical decision making, bladder preservation strategies, modern radiotherapy techniques, the management of oligometastatic disease and the evolving role of checkpoint inhibitor therapy in metastatic disease.Conclusions: These consensus statements provide further guidance on controversial topics in advanced and variant bladder cancer management until a time where further evidence is available to guide our approach. Show less
Heerden, L.E. van; Wieringen, N. van; Koedooder, K.; Rasch, C.R.N.; Pieters, B.R.; Bel, A. 2018
PURPOSE: Structure-based deformable image registration (DIR) can be used to calculate accumulated dose volume histogram parameters for cervical cancer brachytherapy (BT). The purpose of this study... Show morePURPOSE: Structure-based deformable image registration (DIR) can be used to calculate accumulated dose volume histogram parameters for cervical cancer brachytherapy (BT). The purpose of this study is to investigate dose warping uncertainties for the accumulated dose to the 2 cm(3) receiving the highest dose (D-2 cm(3)) in the rectal wall, using a physically realistic model (PRM) describing rectal wall deformation.METHODS AND MATERIALS: For 10 patients, treated with MRI-guided pulsed dose rate BT (two times 24 x 0.75 Gy, given in two applications BT1 and BT2), the planning images were registered with structure-based DIR. The resulting transformation vectors were used to accumulate the total rectum dose from BT. To investigate the dose warping uncertainty, a PRM describing rectal deformation was used. For point pairs on rectum(BTl) and rectum(BT2) that were at the same location according to the PRM, the dose for BT1 and BT2 was added (D-PRM) and compared to the DIR-accumulated dose (D-DIR) in the BT2 point. The remaining distance after DIR between corresponding point pairs, defined as the residual distance, was calculated.RESULTS: For points within the D-2 cm(3) volume, more than 75% was part of the D-2 cm(3) volume according to both PRM and DIR. The absolute dose difference was <7.3 Gy(EQD2), and the median (95th percentile) of the residual distance was 8.7 (22) mm.CONCLUSIONS: DIR corresponded with the PRM for on average 75% of the D-2 cm(3) volume. Local absolute dose differences and residual distances were large. Care should therefore be taken with DIR for dose-warping purposes in BT. (C) 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved. Show less
Purpose: Deformable image registration (DIR) can be used to accumulate the absorbed dose distribution of daily image-guided adaptive external beam radiation treatment (EBRT) and brachytherapy (BT).... Show morePurpose: Deformable image registration (DIR) can be used to accumulate the absorbed dose distribution of daily image-guided adaptive external beam radiation treatment (EBRT) and brachytherapy (BT). Since dose-volume parameter addition assumes a uniform delivered EBRT dose around the planned BT boost, the added value of DIR over direct addition was investigated for dose accumulation in bladder and rectum.Material and methods: For 10 patients (EBRT 46/46.2 Gy(EQD2), EBRT + BT: D-90 85-90 Gy(EQD2), in equivalent dose in 2 Gy fractions), the actually delivered dose from adaptive volumetric-modulated arc therapy (VMAT)/intensity-modulated radiotherapy (IMRT) EBRT was calculated using the daily anatomy from the cone-beam computed tomography (CBCT) scans acquired prior to irradiation. The CBCT of the first EBRT fraction and the BT planning MRI were registered using DIR. The cumulative dose to the 2 cm(3) with the highest dose (D-2cm3) from EBRT and BT to the bladder and rectum was calculated and compared to direct addition assuming a uniform EBRT dose (UD).Results: Differences (DIR-UD) in the total EBRT + BT dose ranged between -0.2-3.9 Gy(EQD2) (bladder) and -1.0-3.7 Gy(EQD2) (rectum). The total EBRT + BT dose calculated with DIR was at most 104% of the dose calculated with the UD method.Conclusions: Differences between UD and DIR were small (< 3.9 Gy(EQD2)). The dose delivered with adaptive VMAT/IMRT EBRT to bladder and rectum near the planned BT boost can be considered uniform for the evaluation of bladder/rectum D-2cm3. Show less
Heerden, L.E. van; Kesteren, Z. van; Gurney-Champion, O.J.; Houweling, A.C.; Koedooder, K.; Rasch, C.R.N.; ... ; Bel, A. 2017
Purpose: To quantify magnetic resonance imaging (MRI)distortions on a plastic intracavitary/interstitial applicator with plastic needles at a field strength of 3 T and to determine the dosimetric... Show morePurpose: To quantify magnetic resonance imaging (MRI)distortions on a plastic intracavitary/interstitial applicator with plastic needles at a field strength of 3 T and to determine the dosimetric impact, using patient data.Methods and Materials: For 11 cervical cancer patients, our clinical MRI protocol was extended with 3 scans. From the first scan, a multi-echo acquisition, a map of the magnetic field (B-0) was calculated and used to quantify the field inhomogeneity. The expected displacements of the applicator were quantified for the clinical sequence using the measured field inhomogeneity and the clinical sequence's bandwidth. The second and third scan were our routine clinical sequence (duration: <5 minutes each), acquired consecutively using opposing readout directions. The displacement of the applicator between these scans is approximately twice the displacement due to B0 inhomogeneity. The impact of the displacement on the dose was determined by reconstructing the applicator on both scans. The applicator was then shifted and rotated the same distance as the observed displacement to create a worst-case scenario (ie, twice the actual displacement due to B0 inhomogeneity). Next, the dose to 98%/90% (D98/D90) of the clinical target volume at high risk, as well as the dose to the most irradiated 2 cm 3 for bladder and rectum, were calculated for the original plan as well as the shifted plan.Results: For a volume of interest containing the intrauterine device and the ovoids the 95th percentile of the absolute displacement ranged between 0.2 and 0.75 mm, over all patients. For all patients, the difference in D98/D90 in the opposing readout scans with the original plan was at most 4.7%/ 4.3%. For the dose to the most irradiated 2 cm 3 of bladder/rectum, the difference was at most 6.0%/ 6.3%.Conclusions: The dosimetric impact of distortions on this plastic applicator with plastic needles is limited. Applicator reconstruction for brachytherapy planning purposes is feasible at 3 T MRI. (C) 2017 Elsevier Inc. All rights reserved. Show less
Heerden, L.E. van; Houweling, A.C.; Koedooder, K.; Kesteren, Z. van; Wieringen, N. van; Rasch, C.R.N.; ... ; Bel, A. 2017
Background and purpose: Structure -based deformable image registration (DIR) can be used to calculate accumulated brachytherapy (BT) and external -beam radiation therapy (EBRT) dose-volume... Show moreBackground and purpose: Structure -based deformable image registration (DIR) can be used to calculate accumulated brachytherapy (BT) and external -beam radiation therapy (EBRT) dose-volume histogram (DVH) parameters in cervical cancer. Since direct parameter addition does not take dose non uniformity into account, the added value of DIR over addition methods was investigated for bladder and rectum.Materials and methods: For twelve patients (EBRT: 46 Gy, EBRT + BT: D-90 85-90 Gy(EQD2) in equivalent dose in 2 Gy fractions) the EBRT planning CT and BT planning MRI were registered using DIR. Affected lymph nodes, located far from the BT boost region, received an EBRT boost (9.2 Gy) not contributing to the BT boost dose. Cumulative bladder/rectum D-2cm3/D-1cm3 were calculated and compared to direct addition methods, assuming uniform EBRT doses (UD), or overlapping high dose volumes (OHD).Results: Between the three methods, the maximum differences in the cumulative DVH parameters were 3.2 GY(EQD2) (bladder) and 3.3 GY(EQD2) (rectum). The difference between DIR and UD was <1.8 GY(EQD2) for both organs.Conclusions: The UD method provides a better estimate of D2cm3/D1cm3 than the OHD method. There is no added value of DIR since differences with direct addition methods are clinically insignificant. EBRT dose distributions can be considered uniform in bladder and rectum for the evaluated dose parameters. (C) 2017 Elsevier B.V. All rights reserved. Show less
Heerden, L.E. van; Gurney-Champion, O.J.; Kesteren, Z. van; Houweling, A.C.; Koedooder, C.; Rasch, C.R.N.; ... ; Bel, A. 2016
PURPOSE: To quantify distortions on MR images of the Utrecht interstitial CT/MR applicator at a field strength of 3T using an MRI-only method.MATERIALS AND METHODS: An MR-compatible phantom... Show morePURPOSE: To quantify distortions on MR images of the Utrecht interstitial CT/MR applicator at a field strength of 3T using an MRI-only method.MATERIALS AND METHODS: An MR-compatible phantom suspending the applicator in water was built and imaged on a Philips Ingenia 3T MRI scanner. A map of the magnetic field (B-0) was calculated from multiecho images and used to quantify the field inhomogeneity. The expected displacements of the applicator could be quantified using the measured field inhomogeneity and sequence bandwidth. Additionally, two scans were acquired using opposing readout gradients. These scans were rigidly matched and their displacement was compared with the expected displacements from the B-0 map.These same methods were applied in 4 patients. By rigid matching of the scans acquired with opposing readout direction the applicator displacement due to image distortion from B-0 inhomogeneity as well as patient movement and organ deformation was determined.RESULTS: According to the B-0 map, the displacement on the intrauterine device of the plastic brachytherapy applicator was <0.4 mm for both the phantom and patients. Displacements obtained by the opposing readout method were <= 0.8 mm for each patient with a mean +/- SD over the patients of 0.3 +/- 0.1 mm.CONCLUSION: The results of our study indicate that the B-0 method agrees with the opposing readout method. Displacements caused by magnetic field inhomogeneity on 3T MRI were small compared with displacements due to patient movement and organ deformation. (C) 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved. Show less
Pulsed dose rate (PDR) brachytherapy is a treatment modality that combines physical advantages of high dose rate (HDR) brachytherapy with the radiobiological advantages of low dose rate... Show morePulsed dose rate (PDR) brachytherapy is a treatment modality that combines physical advantages of high dose rate (HDR) brachytherapy with the radiobiological advantages of low dose rate brachytherapy. The aim of this review was to describe the effective clinical use of PDR brachytherapy worldwide in different tumour locations. We found 66 articles reporting on clinical PDR brachytherapy including the treatment procedure and outcome. Moreover, PDR brachytherapy has been applied in almost all tumour sites for which brachytherapy is indicated and with good local control and low toxicity. The main advantage of PDR is, because of the small pulse sizes used, the ability to spare normal tissue. In certain cases, HDR resembles PDR brachytherapy by the use of multifractionated low-fraction dose. Show less
Purpose: Radical cystectomy currently is the treatment of choice in muscle-invasive bladder cancer. However, cystectomy is associated with considerable morbidity. Bladder sparing treatment consists... Show morePurpose: Radical cystectomy currently is the treatment of choice in muscle-invasive bladder cancer. However, cystectomy is associated with considerable morbidity. Bladder sparing treatment consists of transurethral resection of the tumor (with or without partial cystectomy), external beam radiotherapy, and brachytherapy. The purpose of this study is to compare bladder preservation with brachytherapy to cystectomy by a systematic review.Material and methods: A systematic review was conducted using PubMed electronic database. Article selection was done independently by two authors. Data were extracted on cause-specific survival and overall survival at 2, 5, and 10 years. Comparison of the two treatment modalities was done by a Weibull survival analysis with metaregression analysis and estimation of Hazard Ratio's (HR's) with 95% confidence intervals (CI).Results: Large differences in tumor staging and tumor grading were found between cystectomy and bladder sparing series. The adjusted HR's for cause-specific survival and overall survival were 1.27 (95% CI: 1.15-1.40) and 0.85 (95% CI: 0.84-0.87), respectively for bladder sparing relative to radical cystectomy.Conclusions: Robustness of the analysis is hampered by the retrospective character of the study and differences in patient characteristics. For selected cases, bladder sparing by brachytherapy leads to at least similar overall survival compared to radical cystectomy for muscle invasive bladder cancer. Show less
Dinkla, A.M.; Pieters, B.R.; Koedooder, K.; Wieringen, N. van; Laarse, R. van der; Grient, J.N. van der; ... ; Bel, A. 2013
Background. Due to improved visibility on MRI, contouring of the prostate is improved compared to CT. The aim of this study was to quantify the benefits of using MRI for treatment planning as... Show moreBackground. Due to improved visibility on MRI, contouring of the prostate is improved compared to CT. The aim of this study was to quantify the benefits of using MRI for treatment planning as compared to CT-based planning for temporary implant prostate brachytherapy. Material and methods. CT and MRI image data of 13 patients were used to delineate the prostate and organs at risk (OARs) and to reconstruct the implanted catheters (typically 12). An experienced treatment planner created plans on the CT-based structure sets (CT-plan) and on the MRI-based structure sets (MRI-plan). Then, active dwell-positions and weights of the CT-plans were transferred to the MRI-based structure sets (CT-plan(MRI-contours)) and resulting dosimetric parameters and tumour control probabilities (TCPs) were studied. Results. For the CT-plan(MRI-contours) a statistically significant lower target coverage was detected: mean V-100 was 95.1% as opposed to 98.3% for the original plans (p < 0.01). Planning on CT caused cold-spots that influence the TCP. MRI-based planning improved the TCPs by 6-10%, depending on the parameters of the radiobiological model used for TCP calculation. Basing the treatment plan on either CT- or MRI-delineations does not influence plan quality. Conclusion. Evaluation of CT-based treatment planning by transferring the plan to MRI reveals underdosage of the prostate, especially at the base side. Planning on MRI can prevent cold-spots in the tumour and improves the TCP. Show less
Dinkla, A.M.; Pieters, B.R.; Koedooder, K.; Meijnen, P.; Wieringen, N. van; Laarse, R. van der; ... ; Bel, A. 2013
Background and purpose: To determine the uncertainties in planned dose associated with catheter and organ movement during 48 hours of stepping source prostate brachytherapy.Material and methods:... Show moreBackground and purpose: To determine the uncertainties in planned dose associated with catheter and organ movement during 48 hours of stepping source prostate brachytherapy.Material and methods: Pulsed-dose. rate (PDR) prostate brachytherapy as a boost is given in 24 pulses every 2 hours, making the total treatment last 48 hours. The entire treatment is based on one plan, created on the planning CT (CT1). Two follow-up CTs (CT2 and CT3) were acquired; halfway through the treatment and at the end of treatment. On these repeat scans the catheters were reconstructed and PTV and OARs were delineated. The original treatment plan was calculated on the repeat CTs. Target coverage V-100%. D-90, dose to 2 cm(3) (D2cm(3)) of the rectum and bladder and dose to 0.1 cm(3) of the urethra were recorded from the recalculated DVHs.Results: On the two repeat CTs the V-100% decreased -1.5% and -2.3% as compared to the planning CT. For the rectum D2cm(3), the average increase was 14.8% (CT1-CT2) and 173% (CT1-CT3.). Increase in bladder D2cm(3) was on average 23.1% (CT1-CT2) and 24.8% (CT1-CT3). For the urethra D0.1cm(3) an average decrease of -2% (CT1-CT2) and -3.2% (CT2-CT3) was observed.Conclusions: Changes in target coverage during treatment were small and considered clinically irrelevant. However, an overall increase in dose to the OARs was found as compared to the planned dose, which should be taken into account during treatment planning. (C) 2012 Elsevier Ireland Ltd. All rights reserved. Show less
Koning, C.C.E.; Blank, L.E.C.M.; Koedooder, C.; Os, R.M. van; Kar, M. van de; Jansen, E.; ... ; Pieters, B.R. 2012
