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Kennedy AC, Douglass MJJ, Santos AMC. Being certain about uncertainties: a robust evaluation method for high-dose-rate prostate brachytherapy treatment plans including the combination of uncertainties. Phys Eng Sci Med 2023; 46:1115-1130. [PMID: 37249825 PMCID: PMC10480262 DOI: 10.1007/s13246-023-01279-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 05/12/2023] [Indexed: 05/31/2023]
Abstract
In high-dose-rate (HDR) prostate brachytherapy the combined effect of uncertainties cause a range of possible dose distributions deviating from the nominal plan, and which are not considered during treatment plan evaluation. This could lead to dosimetric misses for critical structures and overdosing of organs at risk. A robust evaluation method to assess the combination of uncertainties during plan evaluation is presented and demonstrated on one HDR prostate ultrasound treatment plan retrospectively. A range of uncertainty scenarios are simulated by changing six parameters in the nominal plan and calculating the corresponding dose distribution. Two methods are employed to change the parameters, a probabilistic approach using random number sampling to evaluate the likelihood of variation in dose distributions, and a combination of the most extreme possible values to access the worst-case dosimetric outcomes. One thousand probabilistic scenarios were run on the single treatment plan with 43.2% of scenarios passing seven of the eight clinical objectives. The prostate D90 had a standard deviation of 4.4%, with the worst case decreasing the dose by up to 27.2%. The urethra D10 was up to 29.3% higher than planned in the worst case. All DVH metrics in the probabilistic scenarios were found to be within acceptable clinical constraints for the plan under statistical tests for significance. The clinical significance of the results from the robust evaluation method presented on any individual treatment plan needs to be compared in the context of a historical data set that contains patient outcomes with robustness analysis data to ascertain a baseline acceptance.
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Affiliation(s)
- Andrew C. Kennedy
- School of Physical Sciences, University of Adelaide, Adelaide, SA 5005 Australia
| | - Michael J. J. Douglass
- School of Physical Sciences, University of Adelaide, Adelaide, SA 5005 Australia
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, SA 5000 Australia
- Australian Bragg Centre for Proton Therapy and Research, North Terrace, Adelaide, SA 5000 Australia
| | - Alexandre M. C. Santos
- School of Physical Sciences, University of Adelaide, Adelaide, SA 5005 Australia
- Department of Radiation Oncology, Royal Adelaide Hospital, Adelaide, SA 5000 Australia
- Australian Bragg Centre for Proton Therapy and Research, North Terrace, Adelaide, SA 5000 Australia
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Rojo-Santiago J, Habraken SJM, Romero AM, Lathouwers D, Wang Y, Perkó Z, Hoogeman MS. Robustness analysis of CTV and OAR dose in clinical PBS-PT of neuro-oncological tumors: prescription-dose calibration and inter-patient variation with the Dutch proton robustness evaluation protocol. Phys Med Biol 2023; 68:175029. [PMID: 37494944 DOI: 10.1088/1361-6560/acead1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 07/25/2023] [Indexed: 07/28/2023]
Abstract
Objective. The Dutch proton robustness evaluation protocol prescribes the dose of the clinical target volume (CTV) to the voxel-wise minimum (VWmin) dose of 28 scenarios. This results in a consistent but conservative near-minimum CTV dose (D98%,CTV). In this study, we analyzed (i) the correlation between VWmin/voxel-wise maximum (VWmax) metrics and actually delivered dose to the CTV and organs at risk (OARs) under the impact of treatment errors, and (ii) the performance of the protocol before and after its calibration with adequate prescription-dose levels.Approach. Twenty-one neuro-oncological patients were included. Polynomial chaos expansion was applied to perform a probabilistic robustness evaluation using 100,000 complete fractionated treatments per patient. Patient-specific scenario distributions of clinically relevant dosimetric parameters for the CTV and OARs were determined and compared to clinical VWmin and VWmax dose metrics for different scenario subsets used in the robustness evaluation protocol.Main results. The inclusion of more geometrical scenarios leads to a significant increase of the conservativism of the protocol in terms of clinical VWmin and VWmax values for the CTV and OARs. The protocol could be calibrated using VWmin dose evaluation levels of 93.0%-92.3%, depending on the scenario subset selected. Despite this calibration of the protocol, robustness recipes for proton therapy showed remaining differences and an increased sensitivity to geometrical random errors compared to photon-based margin recipes.Significance. The Dutch proton robustness evaluation protocol, combined with the photon-based margin recipe, could be calibrated with a VWmin evaluation dose level of 92.5%. However, it shows limitations in predicting robustness in dose, especially for the near-maximum dose metrics to OARs. Consistent robustness recipes could improve proton treatment planning to calibrate residual differences from photon-based assumptions.
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Affiliation(s)
- Jesús Rojo-Santiago
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, The Netherlands
- Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
| | - Steven J M Habraken
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, The Netherlands
- Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
| | - Alejandra Méndez Romero
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, The Netherlands
- Department of Radiation Oncology, HollandPTC, Delft, The Netherlands
| | - Danny Lathouwers
- Delft University of Technology, Department of Radiation Science and Technology, Delft, The Netherlands
| | - Yibing Wang
- Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
| | - Zoltán Perkó
- Delft University of Technology, Department of Radiation Science and Technology, Delft, The Netherlands
| | - Mischa S Hoogeman
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, Rotterdam, The Netherlands
- Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
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Yagihashi T, Inoue K, Nagata H, Yamanaka M, Yamano A, Suzuki S, Yamakabe W, Sato N, Omura M, Inoue T. Effectiveness of robust optimization against geometric uncertainties in TomoHelical planning for prostate cancer. J Appl Clin Med Phys 2022; 24:e13881. [PMID: 36576418 PMCID: PMC10113685 DOI: 10.1002/acm2.13881] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/11/2022] [Accepted: 12/10/2022] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Geometrical uncertainties in patients can severely affect the quality of radiotherapy. PURPOSE We evaluated the dosimetric efficacy of robust optimization for helical intensity-modulated radiotherapy (IMRT) planning in the presence of patient setup uncertainty and anatomical changes. METHODS Two helical IMRT plans for 10 patients with localized prostate cancer were created using either minimax robust optimization (robust plan) or a conventional planning target volume (PTV) margin approach (PTV plan). Plan robustness was evaluated by creating perturbed dose plans with setup uncertainty from isocenter shifts and anatomical changes due to organ variation. The magnitudes of the geometrical uncertainties were based on the patient setup uncertainty considered during robust optimization, which was identical to the PTV margin. The homogeneity index, and target coverage (TC, defined as the V100% of the clinical target volume), and organs at risk (OAR; rectum and bladder) doses were analyzed for all nominal and perturbed plans. A statistical t-test was performed to evaluate the differences between the robust and PTV plans. RESULTS Comparison of the nominal plans showed that the robust plans had lower OAR doses and a worse homogeneity index and TC than the PTV plans. The evaluations of robustness that considered setup errors more than the PTV margin demonstrated that the worst-case perturbed scenarios for robust plans had significantly higher TC while maintaining lower OAR doses. However, when anatomical changes were considered, improvement in TC from robust optimization was not observed in the worst-case perturbed plans. CONCLUSIONS For helical IMRT planning in localized prostate cancer, robust optimization provides benefits over PTV margin-based planning, including better OAR sparing, and increased robustness against systematic patient-setup errors.
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Affiliation(s)
- Takayuki Yagihashi
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan.,Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku, Tokyo, Japan
| | - Kazumasa Inoue
- Graduate School of Human Health Sciences, Tokyo Metropolitan University, Arakawa-ku, Tokyo, Japan
| | - Hironori Nagata
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan
| | - Masashi Yamanaka
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan.,Medical Physics Laboratory, Division of Health Science, Graduate School of Medicine, Osaka University, Suita-shi, Osaka, Japan
| | - Akihiro Yamano
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan
| | - Shunsuke Suzuki
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan.,Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto, Japan
| | - Wataru Yamakabe
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan
| | - Naoki Sato
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan
| | - Motoko Omura
- Department of Radiation Oncology, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan
| | - Tatsuya Inoue
- Department of Medical Physics, Shonan Kamakura General Hospital, Kamakura City, Kanagawa, Japan.,Department of Radiation Oncology, Juntendo University, Bunkyo-ku, Tokyo, Japan
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Knopf AC, Czerska K, Fracchiolla F, Graeff C, Molinelli S, Rinaldi I, Rucincki A, Sterpin E, Stützer K, Trnkova P, Zhang Y, Chang JY, Giap H, Liu W, Schild SE, Simone CB, Lomax AJ, Meijers A. Clinical necessity of multi-image based (4DMIB) optimization for targets affected by respiratory motion and treated with scanned particle therapy – a comprehensive review. Radiother Oncol 2022; 169:77-85. [DOI: 10.1016/j.radonc.2022.02.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 01/31/2022] [Accepted: 02/14/2022] [Indexed: 12/28/2022]
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Rojo-Santiago J, Habraken SJM, Lathouwers D, Méndez Romero A, Perkó Z, Hoogeman MS. Accurate assessment of a Dutch practical robustness evaluation protocol in clinical PT with pencil beam scanning for neurological tumors. Radiother Oncol 2021; 163:121-127. [PMID: 34352313 DOI: 10.1016/j.radonc.2021.07.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 07/23/2021] [Accepted: 07/24/2021] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE Scenario-based robust optimization and evaluation is commonly used in proton therapy (PT) with pencil beam scanning (PBS) to ensure adequate dose to the clinical target volume (CTV). However, a statistically accurate assessment of the clinical application of this approach is lacking. In this study, we assess target dose in a clinical cohort of neuro-oncological patients, planned according to the DUPROTON robustness evaluation consensus, using polynomial chaos expansion (PCE). MATERIALS AND METHODS A cohort of the first 27 neuro-oncological patients treated at HollandPTC was used, including realistic error distributions derived from geometrical and stopping-power prediction (SPP) errors. After validating the model, PCE-based robustness evaluations were performed by simulating 100.000 complete fractionated treatments per patient to obtain accurate statistics on clinically relevant dosimetric parameters and population-dose histograms. RESULTS Treatment plans that were robust according to clinical protocol and treatment plans in which robustness was sacrificed are easily identified. For robust treatment plans on average, a CTV dose of 3 percentage points (p.p.) more than prescribed was realized (range +2.7 p.p. - +3.5 p.p.) for 98% of the sampled fractionated treatments. For the entire patient cohort on average, a CTV dose of 0.1 p.p. less than prescribed was achieved (range -2.4 p.p. - +0.5 p.p.). For the 6 treatment plans in which robustness was clinically sacrificed, normalized CTV doses of 0.98, 0.94(7)12, 0.94, 0.91, 0.90 and 0.89 were realized. The first of these was clinically borderline non-robust. CONCLUSION The clinical robustness evaluation protocol is safe in terms of CTV dose as all plans that fulfilled the clinical robustness criteria were also robust in the PCE evaluation. Moreover, for plans that were non-robust in the PCE-based evaluation, CTV dose was also lower than prescribed in the clinical evaluation.
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Affiliation(s)
- Jesús Rojo-Santiago
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands; Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands.
| | - Steven J M Habraken
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands; Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
| | - Danny Lathouwers
- Delft University of Technology, Department of Radiation Science and Technology, Delft, The Netherlands
| | - Alejandra Méndez Romero
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands; Department of Radiation Oncology, HollandPTC, Delft, The Netherlands
| | - Zoltán Perkó
- Delft University of Technology, Department of Radiation Science and Technology, Delft, The Netherlands
| | - Mischa S Hoogeman
- Erasmus MC Cancer Institute, University Medical Center Rotterdam, Department of Radiotherapy, The Netherlands; Department of Medical Physics & Informatics, HollandPTC, Delft, The Netherlands
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Buti G, Souris K, Maria Barragán Montero A, Aldo Lee J, Sterpin E. Introducing a probabilistic definition of the target in a robust treatment planning framework. Phys Med Biol 2021; 66. [PMID: 34236043 DOI: 10.1088/1361-6560/ac1265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Accepted: 07/01/2021] [Indexed: 11/11/2022]
Abstract
The 'clinical target distribution' (CTD) has recently been introduced as a promising alternative to the binary clinical target volume (CTV). However, a comprehensive study that considers the CTD, together with geometric treatment uncertainties, was lacking. Because the CTD is inherently a probabilistic concept, this study proposes a fully probabilistic approach that integrates the CTD directly in a robust treatment planning framework. First, the CTD is derived from a reported microscopic tumor infiltration model such that it explicitly features the probability of tumor cell presence in its target definition. Second, two probabilistic robust optimization methods are proposed that evaluate CTD coverage under uncertainty. The first method minimizes the expected-value (EV) over the uncertainty scenarios and the second method minimizes the sum of the expected value and standard deviation (EV-SD), thereby penalizing the spread of the objectives from the mean. Both EV and EV-SD methods introduce the CTD in the objective function by using weighting factors that represent the probability of tumor presence. The probabilistic methods are compared to a conventional worst-case approach that uses the CTV in a worst-case optimization algorithm. To evaluate the treatment plans, a scenario-based evaluation strategy is implemented that combines the effects of microscopic tumor infiltrations with the other geometric uncertainties. The methods are tested for five lung tumor patients, treated with intensity-modulated proton therapy. The results indicate that for the studied patient cases, the probabilistic methods favor the reduction of the esophagus dose but compensate by increasing the high-dose region in a low conflicting organ such as the lung. These results show that a fully probabilistic approach has the potential to obtain clinical benefits when tumor infiltration uncertainties are taken into account directly in the treatment planning process.
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Affiliation(s)
- Gregory Buti
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Avenue Hippocrate 54-Box B1.54.07, B-1200 Brussels, Belgium
| | - Kevin Souris
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Avenue Hippocrate 54-Box B1.54.07, B-1200 Brussels, Belgium
| | - Ana Maria Barragán Montero
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Avenue Hippocrate 54-Box B1.54.07, B-1200 Brussels, Belgium
| | - John Aldo Lee
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Avenue Hippocrate 54-Box B1.54.07, B-1200 Brussels, Belgium
| | - Edmond Sterpin
- Université Catholique de Louvain, Institut de Recherche Expérimentale et Clinique (IREC), Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Avenue Hippocrate 54-Box B1.54.07, B-1200 Brussels, Belgium.,Katholieke Universiteit Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, UZ Herestraat 49-Box 7003, B-3000 Leuven, Belgium
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