Knopf, Antje

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Antje
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Knopf, Antje

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2022 - 202415

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  • Vorschaubild
    Publikation
    Possible association of dose rate and the development of late visual toxicity for patients with intracranial tumours treated with pencil beam scanned proton therapy
    (BioMed Central, 17.06.2024) Meijers, Arturs; Daartz, Juliane; Knopf, Antje; Van Heerden, Michelle; Bizzocchi, Nicola; Vazquez, Miriam Varela; Bachtiary, Barbara; Pica, Alessia; Shih, Helen A.; Weber, Damien Charles
    Background and purpose Rare but severe toxicities of the optic apparatus have been observed after treatment of intracranial tumours with proton therapy. Some adverse events have occurred at unusually low dose levels and are thus difficult to understand considering dose metrics only. When transitioning from double scattering to pencil beam scanning, little consideration was given to increased dose rates observed with the latter delivery paradigm. We explored if dose rate related metrics could provide additional predicting factors for the development of late visual toxicities. Materials and methods Radiation-induced intracranial visual pathway lesions were delineated on MRI for all index cases. Voxel-wise maximum dose rate (MDR) was calculated for 2 patients with observed optic nerve toxicities (CTCAE grade 3 and 4), and 6 similar control cases. Additionally, linear energy transfer (LET) related dose enhancing metrics were investigated. Results For the index cases, which developed toxicities at low dose levels (mean, 50 GyRBE), some dose was delivered at higher instantaneous dose rates. While optic structures of non-toxicity cases were exposed to dose rates of up to 1 to 3.2 GyRBE/s, the pre-chiasmatic optic nerves of the 2 toxicity cases were exposed to dose rates above 3.7 GyRBE/s. LET-related metrics were not substantially different between the index and non-toxicity cases. Conclusions Our observations reveal large variations in instantaneous dose rates experienced by different volumes within our patient cohort, even when considering the same indications and beam arrangement. High dose rate regions are spatially overlapping with the radiation induced toxicity areas in the follow up images. At this point, it is not feasible to establish causality between exposure to high dose rates and the development of late optic apparatus toxicities due to the low incidence of injury.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Kein Vorschaubild vorhanden
    Publikation
    Organ motion in particle therapy and the role of imaging
    (IOP Publishing, 06/2024) Paganelli, Chiara; Molinelli, Silvia; Knopf, Antje; Paganelli, Chiara; Gianoli, Chiara; Knopf, Antje
    Organ motion is one of the main challenges to account for in particle therapy to plan and deliver an accurate treatment. In this chapter, we will explain the concept of organ motion in terms of inter- and intra-fraction variations. The current inter- and intra-fraction motion compensation techniques demanding for imaging will be also reported.
    04A - Beitrag Sammelband
  • Kein Vorschaubild vorhanden
    Publikation
    Conclusions and future perspectives of imaging in particle therapy
    (IOP Publishing, 06/2024) Paganelli, Chiara; Gianoli, Chiara; Knopf, Antje; Paganelli, Chiara; Gianoli, Chiara; Knopf, Antje
    In this chapter, we will consolidate the concluding remarks presented throughout the preceding chapters, with a specific emphasis on the technical and methodological advancements in image-guided particle therapy, as well as elucidating the future trajectory of this field.
    04A - Beitrag Sammelband
  • Kein Vorschaubild vorhanden
    Publikation
    Treatment verification in particle therapy
    (IOP Publishing, 01.06.2024) Gianoli, Chiara; De Simoni, M.; Knopf, Antje; Paganelli, Chiara; Gianoli, Chiara; Knopf, Antje
    To make the most of the physical and biological potentials of Particle Therapy (PT), it would be extremely desirable to verify dose deposition in vivo. In this chapter, we describe and compare in vivo range verification methods currently being proposed, developed or clinically implemented, including PET and prompt gamma imaging. The potential of other emerging techniques for indirect treatment verification will be also cited.
    04A - Beitrag Sammelband
  • Kein Vorschaubild vorhanden
    Publikation
    Integration of imaging in clinical protocols of particle therapy
    (IOP Publishing, 06/2024) Trnkova, P.; Bolsi, Alessandra; Knopf, Antje; Hoffmann, A.; Paganelli, Chiara; Gianoli, Chiara; Knopf, Antje
    04A - Beitrag Sammelband
  • Vorschaubild
    Publikation
    A review of the clinical introduction of 4D particle therapy research concepts
    (Elsevier, 01/2024) Knäusl, Barbara; Belotti, Gabriele; Bertholet, Jenny; Daartz, Juliane; Flampouri, Stella; Hoogeman, Mischa; Knopf, Antje; Lin, Haibo; Moerman, Astrid; Paganelli, Chiara; Rucinski, Antoni; Schulte, Reinhard; Shimizu, Shing; Stützer, Kristin; Zhang, Xiaodong; Zhang, Ye; Czerska, Katarzyna
    Background and purpose: Many 4D particle therapy research concepts have been recently translated into clinics, however, remaining substantial differences depend on the indication and institute-related aspects. This work aims to summarise current state-of-the-art 4D particle therapy technology and outline a roadmap for future research and developments. Material and methods: This review focused on the clinical implementation of 4D approaches for imaging, treatment planning, delivery and evaluation based on the 2021 and 2022 4D Treatment Workshops for Particle Therapy as well as a review of the most recent surveys, guidelines and scientific papers dedicated to this topic. Results: Available technological capabilities for motion surveillance and compensation determined the course of each 4D particle treatment. 4D motion management, delivery techniques and strategies including imaging were diverse and depended on many factors. These included aspects of motion amplitude, tumour location, as well as accelerator technology driving the necessity of centre-specific dosimetric validation. Novel methodologies for X-ray based image processing and MRI for real-time tumour tracking and motion management were shown to have a large potential for online and offline adaptation schemes compensating for potential anatomical changes over the treatment course. The latest research developments were dominated by particle imaging, artificial intelligence methods and FLASH adding another level of complexity but also opportunities in the context of 4D treatments. Conclusion: This review showed that the rapid technological advances in radiation oncology together with the available intrafractional motion management and adaptive strategies paved the way towards clinical implementation.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    A survey of practice patterns for real-time intrafractional motion-management in particle therapy
    (Elsevier, 26.04.2023) Zhang, Ye; Trnkova, Petra; Toshito, Toshiyuki; Heijmen, Ben; Richter, Christian; Aznar, Marianne; Albertini, Francesca; Bolsi, Alexandra; Daartz, Juliane; Bertholet, Jenny; Knopf, Antje
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    A survey of practice patterns for adaptive particle therapy for interfractional changes
    (Elsevier, 04/2023) Trnkova, Petra; Zhang, Ye; Toshito, Toshiyuki; Heijmen, Ben; Richter, Christian; Aznar, Marianne C.; Albertini, Francesca; Bolsi, Alessandra; Daartz, Juliane; Knopf, Antje; Bertholet, Jenny
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Robustness assessment of clinical adaptive proton and photon radiotherapy for oesophageal cancer in the model-based approach
    (Elsevier, 12/2022) Visser, Sabine; O. Ribeiro, Cássia; Dieters, Margriet; Mul, Veronique E.; Niezink, Anne G.H.; van der Schaaf, Arjen; Langendijk, Johannes A.; Korevaar, Erik W.; Both, Stefan; Muijs, Christina T.; Knopf, Antje
    Purpose In the Netherlands, oesophageal cancer (EC) patients are selected for intensity modulated proton therapy (IMPT) using the expected normal tissue complication probability reduction (ΔNTCP) when treating with IMPT compared to volumetric modulated arc therapy (VMAT). In this study, we evaluate the robustness of the first EC patients treated with IMPT in our clinic in terms of target and organs-at-risk (OAR) dose with corresponding NTCP, as compared to VMAT. Materials and Methods For 20 consecutive EC patients, clinical IMPT and VMAT plans were created on the average planning 4DCT. Both plans were robustly evaluated on weekly repeated 4DCTs and if target coverage degraded, replanning was performed. Target coverage was evaluated for complete treatment trajectories with and without replanning. The planned and accumulated mean lung dose (MLD) and mean heart dose (MHD) were additionally evaluated and translated into NTCP. Results Replanning in the clinic was performed more often for IMPT (15x) than would have been needed for VMAT (8x) (p = 0.11). Both adaptive treatments would have resulted in adequate accumulated target dose coverage. Replanning in the first week of treatment had most clinical impact, as anatomical changes resulting in insufficient accumulated target coverage were already observed at this stage. No differences were found in MLD between the planned dose and the accumulated dose. Accumulated MHD differed from the planned dose (p < 0.001), but since these differences were similar for VMAT and IMPT (1.0 and 1.5 Gy, respectively), the ΔNTCP remained unchanged. Conclusion Following an adaptive clinical workflow, adequate target dose coverage and stable OAR doses with corresponding NTCPs was assured for both IMPT and VMAT.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild
    Publikation
    Deep learning–based 4D‐synthetic CTs from sparse‐view CBCTs for dose calculations in adaptive proton therapy
    (Wiley, 27.08.2022) Thummerer, Adrian; Seller Oria, Carmen; Zaffino, Paolo; Visser, Sabine; Meijers, Arturs; Guterres Marmitt, Gabriel; Wijsman, Robin; Seco, Joao; Langendijk, Johannes Albertus; Spadea, Maria Francesca; Both, Stefan; Knopf, Antje
    Background Time-resolved 4D cone beam–computed tomography (4D-CBCT) allows a daily assessment of patient anatomy and respiratory motion. However, 4D-CBCTs suffer from imaging artifacts that affect the CT number accuracy and prevent accurate proton dose calculations. Deep learning can be used to correct CT numbers and generate synthetic CTs (sCTs) that can enable CBCT-based proton dose calculations. Purpose In this work, sparse view 4D-CBCTs were converted into 4D-sCT utilizing a deep convolutional neural network (DCNN). 4D-sCTs were evaluated in terms of image quality and dosimetric accuracy to determine if accurate proton dose calculations for adaptive proton therapy workflows of lung cancer patients are feasible. Methods A dataset of 45 thoracic cancer patients was utilized to train and evaluate a DCNN to generate 4D-sCTs, based on sparse view 4D-CBCTs reconstructed from projections acquired with a 3D acquisition protocol. Mean absolute error (MAE) and mean error were used as metrics to evaluate the image quality of single phases and average 4D-sCTs against 4D-CTs acquired on the same day. The dosimetric accuracy was checked globally (gamma analysis) and locally for target volumes and organs-at-risk (OARs) (lung, heart, and esophagus). Furthermore, 4D-sCTs were also compared to 3D-sCTs. To evaluate CT number accuracy, proton radiography simulations in 4D-sCT and 4D-CTs were compared in terms of range errors. The clinical suitability of 4D-sCTs was demonstrated by performing a 4D dose reconstruction using patient specific treatment delivery log files and breathing signals. Results 4D-sCTs resulted in average MAEs of 48.1 ± 6.5 HU (single phase) and 37.7 ± 6.2 HU (average). The global dosimetric evaluation showed gamma pass ratios of 92.3% ± 3.2% (single phase) and 94.4% ± 2.1% (average). The clinical target volume showed high agreement in D98 between 4D-CT and 4D-sCT, with differences below 2.4% for all patients. Larger dose differences were observed in mean doses of OARs (up to 8.4%). The comparison with 3D-sCTs showed no substantial image quality and dosimetric differences for the 4D-sCT average. Individual 4D-sCT phases showed slightly lower dosimetric accuracy. The range error evaluation revealed that lung tissues cause range errors about three times higher than the other tissues. Conclusion In this study, we have investigated the accuracy of deep learning–based 4D-sCTs for daily dose calculations in adaptive proton therapy. Despite image quality differences between 4D-sCTs and 3D-sCTs, comparable dosimetric accuracy was observed globally and locally. Further improvement of 3D and 4D lung sCTs could be achieved by increasing CT number accuracy in lung tissues.
    01A - Beitrag in wissenschaftlicher Zeitschrift