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di Franco F, Baudier T, Pialat PM, Munoz A, Martinon M, Pommier P, Sarrut D, Biston MC. Ultra-hypofractionated prostate cancer radiotherapy: Dosimetric impact of real-time intrafraction prostate motion and daily anatomical changes. Phys Med 2024; 118:103207. [PMID: 38215607 DOI: 10.1016/j.ejmp.2024.103207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 11/28/2023] [Accepted: 01/04/2024] [Indexed: 01/14/2024] Open
Abstract
PURPOSE To retrospectively assess the differences between planned and delivered dose during ultra-hypofractionated (UHF) prostate cancer treatments, by evaluating the dosimetric impact of daily anatomical variations alone, and in combination with prostate intrafraction motion. METHODS Prostate intrafraction motion was recorded with a transperineal ultrasound probe in 15 patients treated by UHF radiotherapy (36.25 Gy/5 fractions). The dosimetric objective was to cover 99 % of the clinical target volume with the 100 % prescription isodose line. After treatment, planning CT (pCT) images were deformably registered onto daily Cone Beam CT to generate pseudo-CT for dose accumulation (accumulated CT, aCT). The interplay effect was accounted by synchronizing prostatic shifts and beam geometry. Finally, the shifted dose maps were accumulated (moved-accumulated CT, maCT). RESULTS No significant change in daily CTV volumes was observed. Conversely, CTV V100% was 98.2 ± 0.8 % and 94.7 ± 2.6 % on aCT and maCT, respectively, compared with 99.5 ± 0.2 % on pCT (p < 0.0001). Bladder volume was smaller than planned in 76 % of fractions and D5cc was 33.8 ± 3.2 Gy and 34.4 ± 3.4 Gy on aCT (p = 0.02) and maCT (p = 0.01) compared with the pCT (36.0 ± 1.1 Gy). The rectum was smaller than planned in 50.3 % of fractions, but the dosimetric differences were not statistically significant, except for D1cc, found smaller on the maCT (33.2 ± 3.2 Gy, p = 0.02) compared with the pCT (35.3 ± 0.7 Gy). CONCLUSIONS Anatomical variations and prostate movements had more important dosimetric impact than anatomical variations alone, although, in some cases, the two phenomena compensated. Therefore, an efficient IGRT protocol is required for treatment implementation to reduce setup errors and control intrafraction motion.
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Affiliation(s)
- Francesca di Franco
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France; Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC UMR5821, 38000 Grenoble, France.
| | - Thomas Baudier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | | | - Alexandre Munoz
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | | | - Pascal Pommier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | - David Sarrut
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | - Marie-Claude Biston
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
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Snyder J, Smith B, Aubin JS, Shepard A, Hyer D. Simulating an intra-fraction adaptive workflow to enable PTV margin reduction in MRIgART volumetric modulated arc therapy for prostate SBRT. Front Oncol 2024; 13:1325105. [PMID: 38260830 PMCID: PMC10800949 DOI: 10.3389/fonc.2023.1325105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 12/18/2023] [Indexed: 01/24/2024] Open
Abstract
Purpose This study simulates a novel prostate SBRT intra-fraction re-optimization workflow in MRIgART to account for prostate intra-fraction motion and evaluates the dosimetric benefit of reducing PTV margins. Materials and methods VMAT prostate SBRT treatment plans were created for 10 patients using two different PTV margins, one with a 5 mm margin except 3 mm posteriorly (standard) and another using uniform 2 mm margins (reduced). All plans were prescribed to 36.25 Gy in 5 fractions and adapted onto each daily MRI dataset. An intra-fraction adaptive workflow was simulated for the reduced margin group by synchronizing the radiation delivery with target position from cine MRI imaging. Intra-fraction delivered dose was reconstructed and prostate DVH metrics were evaluated under three conditions for the reduced margin plans: Without motion compensation (no-adapt), with a single adapt prior to treatment (ATP), and lastly for intra-fraction re-optimization during delivery (intra). Bladder and rectum DVH metrics were compared between the standard and reduced margin plans. Results As expected, rectum V18 Gy was reduced by 4.4 ± 3.9%, D1cc was reduced by 12.2 ± 6.8% (3.4 ± 2.3 Gy), while bladder reductions were 7.8 ± 5.6% for V18 Gy, and 9.6 ± 7.3% (3.4 ± 2.5 Gy) for D1cc for the reduced margin reference plans compared to the standard PTV margin. For the intrafraction replanning approach, average intra-fraction optimization times were 40.0 ± 2.9 seconds, less than the time to deliver one of the four VMAT arcs (104.4 ± 9.3 seconds) used for treatment delivery. When accounting for intra-fraction motion, prostate V36.25 Gy was on average 96.5 ± 4.0%, 99.1 ± 1.3%, and 99.6 ± 0.4 for the non-adapt, ATP, and intra-adapt groups, respectively. The minimum dose received by the prostate was less than 95% of the prescription dose in 84%, 36%, and 10% of fractions, for the non-adapt, ATP, and intra-adapt groups, respectively. Conclusions Intra-fraction re-optimization improves prostate coverage, specifically the minimum dose to the prostate, and enables PTV margin reduction and subsequent OAR sparing. Fast re-optimizations enable uninterrupted treatment delivery.
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Affiliation(s)
- Jeffrey Snyder
- Department of Radiation Oncology, University of Iowa Hospitals and Clinics, Iowa City, IA, United States
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Panizza D, Faccenda V, Arcangeli S, De Ponti E. Treatment Optimization in Linac-Based SBRT for Localized Prostate Cancer: A Single-Arc versus Dual-Arc Plan Comparison. Cancers (Basel) 2023; 16:13. [PMID: 38201441 PMCID: PMC10778084 DOI: 10.3390/cancers16010013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 12/12/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
This study aimed to comprehensively present data on treatment optimization in linac-based SBRT for localized prostate cancer at a single institution. Moreover, the dosimetric quality and treatment efficiency of single-arc (SA) versus dual-arc (DA) VMAT planning and delivery approaches were compared. Re-optimization was performed on twenty low-to-intermediate-risk- (36.25 Gy in 5 fractions) and twenty high-risk (42.7 Gy in 7 fractions) prostate plans initially administered with the DA FFF-VMAT technique in 2021. An SA approach was adopted, incorporating new optimization parameters based on increased planning and clinical experience. Analysis included target coverage, organ-at-risk (OAR) sparing, treatment delivery time, and the pre-treatment verification's gamma analysis-passing ratio. The SA optimization technique has consistently produced superior plans. Rectum and bladder mean doses were significantly reduced, and comparable target coverage and homogeneity were achieved in order to maintain a urethra protection strategy. The mean SA treatment delivery time was reduced by 22%; the mean monitor units increased due to higher plan complexity; and dose measurements demonstrated optimal agreement with calculations. The substantial reduction in treatment delivery time decreased the probability of prostate motion beyond the applied margins, suggesting potential decrease in treatment-related toxicity and improved target coverage in prostate SBRT. Further investigations are warranted to assess the long-term clinical outcomes.
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Affiliation(s)
- Denis Panizza
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy; (V.F.); (E.D.P.)
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy;
| | - Valeria Faccenda
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy; (V.F.); (E.D.P.)
| | - Stefano Arcangeli
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy;
- Radiation Oncology Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
| | - Elena De Ponti
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy; (V.F.); (E.D.P.)
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy;
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Faccenda V, Panizza D, Daniotti MC, Pellegrini R, Trivellato S, Caricato P, Lucchini R, De Ponti E, Arcangeli S. Dosimetric Impact of Intrafraction Prostate Motion and Interfraction Anatomical Changes in Dose-Escalated Linac-Based SBRT. Cancers (Basel) 2023; 15:cancers15041153. [PMID: 36831496 PMCID: PMC9954235 DOI: 10.3390/cancers15041153] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 01/23/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023] Open
Abstract
The dosimetric impact of intrafraction prostate motion and interfraction anatomical changes and the effect of beam gating and motion correction were investigated in dose-escalated linac-based SBRT. Fifty-six gated fractions were delivered using a novel electromagnetic tracking device with a 2 mm threshold. Real-time prostate motion data were incorporated into the patient's original plan with an isocenter shift method. Delivered dose distributions were obtained by recalculating these motion-encoded plans on deformed CTs reflecting the patient's CBCT daily anatomy. Non-gated treatments were simulated using the prostate motion data assuming that no treatment interruptions have occurred. The mean relative dose differences between delivered and planned treatments were -3.0% [-18.5-2.8] for CTV D99% and -2.6% [-17.8-1.0] for PTV D95%. The median cumulative CTV coverage with 93% of the prescribed dose was satisfactory. Urethra sparing was slightly degraded, with the maximum dose increased by only 1.0% on average, and a mean reduction in the rectum and bladder doses was seen in almost all dose metrics. Intrafraction prostate motion marginally contributed in gated treatments, while in non-gated treatments, further deteriorations in the minimum target coverage and bladder dose metrics would have occurred on average. The implemented motion management strategy and the strict patient preparation regimen, along with other treatment optimization strategies, ensured no significant degradations of dose metrics in delivered treatments.
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Affiliation(s)
- Valeria Faccenda
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
| | - Denis Panizza
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy
| | - Martina Camilla Daniotti
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
- Department of Physics, University of Milan, 20133 Milan, Italy
| | | | - Sara Trivellato
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
| | - Paolo Caricato
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
| | - Raffaella Lucchini
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy
| | - Elena De Ponti
- Medical Physics Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy
| | - Stefano Arcangeli
- School of Medicine and Surgery, University of Milan Bicocca, 20126 Milan, Italy
- Radiation Oncology Department, Fondazione IRCCS San Gerardo dei Tintori, 20900 Monza, Italy
- Correspondence:
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Abstract
BACKGROUND Reduced planning target volume (PTV) margins are commonly used in stereotactic body radiotherapy (SBRT) of the prostate. In addition, MR-only treatment planning is becoming more common in prostate radiotherapy and compared to CT-MRI-based contouring results in notable smaller clinical target volume (CTV). Tight PTV margins coupled with MR-only planning raise a concern whether the margins are adequate enough to cover possible volumetric changes of the prostate. The aim of this study was to evaluate the volumetric change of the prostate and its effect on PTV margin during 5x7.25 Gy SBRT of the prostate. MATERIAL AND METHODS Twenty patients were included in the study. Three MRI scans, first prior to treatment (baseline), second after third fraction (mid-treatment) and third after fifth fraction (end-treatment) were acquired for each patient. Prostate contours were delineated on each MRI scan and used to assess the prostate volume and maximum prostate diameter on left-right (LR), anterior-posterior (AP) and superior-inferior (SI) directions at baseline, mid- and end-treatment. RESULTS Median (IQR) change in the prostate volume relative to the baseline was 12.0% (3.1, 17.7) and 9.2% (2.0, 18.9) at the mid- and end-treatment, respectively, and the change was statistically significant (p = 0.004 and p = 0.020, respectively). Compared to the baseline, median increase in the maximum LR, SI and AP prostate diameters were 0.8, 2.3 and 1.5 mm at mid-treatment, and 0.5, 2.5 and 2.3 mm at end-treatment, respectively. CONCLUSION If prostate contouring is based solely on MRI (e.g., in MR-only protocol), additional margin of 1-2 mm should be considered to account for prostate swelling. The study is part of clinical trial NCT02319239.
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Affiliation(s)
- Antti Vanhanen
- Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, Tampere, Finland
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Tampere, Finland
| | - Petri Reinikainen
- Department of Oncology, Unit of Radiotherapy, Tampere University Hospital, Tampere, Finland
| | - Mika Kapanen
- Department of Medical Physics, Medical Imaging Center, Tampere University Hospital, Tampere, Finland
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Muurholm CG, Ravkilde T, De Roover R, Skouboe S, Hansen R, Crijns W, Depuydt T, Poulsen PR. Experimental investigation of dynamic real-time rotation-including dose reconstruction during prostate tracking radiotherapy. Med Phys 2022; 49:3574-3584. [PMID: 35395104 PMCID: PMC9322296 DOI: 10.1002/mp.15660] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Revised: 02/12/2022] [Accepted: 03/30/2022] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Hypofractionation in prostate radiotherapy is of increasing interest. Steep dose gradients and a large weight on each individual fraction emphasize the need for motion management. Real-time motion management techniques such as multi-leaf collimator (MLC) tracking or couch tracking typically adjust for translational motion while rotations remain uncompensated with unknown dosimetric impact. PURPOSE The purpose of this study is to demonstrate and validate dynamic real-time rotation-including dose reconstruction during radiotherapy experiments with and without MLC and couch tracking. METHODS Real-time dose reconstruction was performed using the in-house developed software DoseTracker. DoseTracker receives streamed target positions and accelerator parameters during treatment delivery and uses a pencil beam algorithm with water density assumption to reconstruct the dose in a moving target. DoseTracker's ability to reconstruct motion-induced dose errors in a dynamically rotating and translating target was investigated during three different scenarios: (1) no motion compensation and translational motion correction with (2) MLC tracking and (3) couch tracking. In each scenario, dose reconstruction was performed online and in real-time during delivery of two dual-arc volumetric modulated arc therapy (VMAT) prostate plans with a prescribed fraction dose of 7 Gy to the prostate and simultaneous intraprostatic lesion boosts with doses of at least 8 Gy, but up to 10 Gy as long as the organs-at-risk dose constraints were fulfilled. The plans were delivered to a pelvis phantom that replicated three patient-measured motion traces using a rotational insert with 21 layers of EBT3 film spaced 2.5 mm apart. DoseTracker repeatedly calculated the actual motion-including dose increment and the planned static dose increment since the last calculation in 84500 points in the film stack. The experiments were performed with a TrueBeam accelerator with MLC and couch tracking based on electromagnetic transponders embedded in the film stack. The motion-induced dose error was quantified as the difference between the final cumulative dose with motion and without motion using the 2D 2%/2mm γ-failure rate and the difference in dose to 95% of the clinical target volume (CTV ΔD95% ) and the gross target volume (GTV ΔD95% ) as well as the difference in dose to 0.1 cm3 of the urethra, bladder, and rectum (ΔD0.1CC ). The motion-induced errors were compared between dose reconstructions and film measurements. RESULTS The dose was reconstructed in all calculation points at a mean frequency of 4.7 Hz. The root-mean-square difference between real-time reconstructed and film measured motion-induced errors was 3.1%-points (γ-failure rate), 0.13 Gy (CTV ΔD95% ), 0.23 Gy (GTV ΔD95% ), 0.19 Gy (urethra ΔD0.1CC ), 0.09 Gy (bladder ΔD0.1CC ), and 0.07 Gy (rectum ΔD0.1CC ). CONCLUSIONS In a series of phantom experiments, online real-time rotation-including dose reconstruction was performed for the first time. The calculated motion-induced errors agreed well with film measurements. The dose reconstruction provides a valuable tool for monitoring dose delivery and investigating the efficacy of advanced motion-compensation techniques in the presence of translational and rotational motion. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Thomas Ravkilde
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Robin De Roover
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Simon Skouboe
- Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Rune Hansen
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark
| | - Wouter Crijns
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Tom Depuydt
- Department of Oncology, KU Leuven, Leuven, Belgium.,Department of Radiation Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Per R Poulsen
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark.,Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
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di Franco F, Baudier T, Gassa F, Munoz A, Martinon M, Charcosset S, Vigier-Lafosse E, Pommier P, Sarrut D, Biston MC. Minimum non-isotropic and asymmetric margins for taking into account intrafraction prostate motion during moderately hypofractionated radiotherapy. Phys Med 2022; 96:114-120. [PMID: 35278928 DOI: 10.1016/j.ejmp.2022.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 03/04/2022] [Accepted: 03/04/2022] [Indexed: 12/11/2022] Open
Abstract
PURPOSE To investigate the impact on dose distribution of intrafraction motion during moderate hypofractionated prostate cancer treatments and to estimate minimum non-isotropic and asymmetric (NI-AS) treatment margins taking motion into account. METHODS Prostate intrafraction 3D displacements were recorded with a transperineal ultrasound probe and were evaluated in 46 prostate cancer patients (876 fractions) treated by moderate hypofractionated radiation therapy (60 Gy in 20 fractions). For 18 patients (346 fractions), treatment plans were recomputed increasing CTV-to-PTV margins from 0 to 6 mm with an auto-planning optimization algorithm. Dose distribution was estimated using the voxel shifting method by displacing CTV structure according to the retrieved movements. Time-dependent margins were finally calculated using both van Herk's formula and the voxel shifting method. RESULTS Mean intrafraction prostate displacements observed were -0.02 ± 0.52 mm, 0.27 ± 0.78 mm and -0.43 ± 1.06 mm in left-right, supero-inferior and antero-posterior directions, respectively. The CTV dosimetric coverage increased with increased CTV-to-PTV margins but it decreased with time. Hence using van Herk's formula, after 7 min of treatment, a margin of 0.4 and 0.5 mm was needed in left and right, 1.5 and 0.7 mm in inferior and superior and 1.1 and 3.2 mm in anterior and posterior directions, respectively. Conversely, using the voxel shifting method, a margin of 0 mm was needed in left-right, 2 mm in superior, 3 mm in inferior and anterior and 5 mm in posterior directions, respectively. With this latter NI-AS margin strategy, the dosimetric target coverage was equivalent to the one obtained with a 5 mm homogeneous margin. CONCLUSIONS NI-AS margins would be required to optimally take into account intrafraction motion.
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Affiliation(s)
- Francesca di Franco
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | - Thomas Baudier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | - Frédéric Gassa
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | - Alexandre Munoz
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | | | | | | | - Pascal Pommier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | - David Sarrut
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | - Marie-Claude Biston
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France.
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Siciarz P, McCurdy B, Hanumanthappa N, Van Uytven E. Adaptive radiation therapy strategies in the treatment of prostate cancer patients using hypofractionated VMAT. J Appl Clin Med Phys 2021; 22:7-26. [PMID: 34787360 PMCID: PMC8664140 DOI: 10.1002/acm2.13415] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 07/21/2021] [Accepted: 08/20/2021] [Indexed: 11/13/2022] Open
Abstract
PURPOSE To perform a comprehensive evaluation of eight adaptive radiation therapy strategies in the treatment of prostate cancer patients who underwent hypofractionated volumetric modulated arc therapy (VMAT) treatment. MATERIAL AND METHODS The retrospective study included 20 prostate cancer patients treated with 40 Gy total dose over five fractions (8 Gy/fraction) using VMAT. Daily cone beam computed tomography images were acquired before the delivery of every fraction and then, with the application of deformable image registration used for the estimation of daily dose, contouring and plan re-optimization. Dosimetric benefits of the various ART strategies were quantified by the comparison of dose and dose-volume metrics derived from treatment planning objectives for original treatment plan and adapted plans with the consideration of target volumes (PTV and CTV) as well as critical structures (bladder, rectum, left, and right femoral heads). RESULTS Percentage difference (ΔD) between planning objectives and delivered dose in the D99% > 4000cGy (CTV) metric was -3.9% for the non-ART plan and 2.1% to 4.1% for ART plans. For D99% > 3800cGy and Dmax < 4280cGy (PTV), ΔD was -11.2% and -6.5% for the non-ART plan as well as -3.9% to -1.6% and -0.2% to 1.8% for ART plans, respectively. For D15% < 3200 cGy and D20% < 2800 cGy (bladder), ΔD was -62.4% and -68.8% for the non-ART plan as well as -60.0% to -57.4% and -67.0% to -64.0% for ART plans. For D15% < 3200 cGy and D20% < 2800 cGy (rectum), ΔD was -11.4% and -8.15% for non-ART plan as well as -14.9% to -9.0% and -11.8% to -5.1% for ART plans. CONCLUSIONS Daily on-line adaptation approaches were the most advantageous, although strategies adapting every other fraction were also impactful while reducing relative workload as well. Offline treatment adaptations were shown to be less beneficial due to increased dose delivered to bladder and rectum compared toother ART strategies.
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Affiliation(s)
- Pawel Siciarz
- Department of Medical PhysicsCancerCare ManitobaWinnipegManitobaCanada
- Department of Physics and AstronomyUniversity of ManitobaWinnipegManitobaCanada
| | - Boyd McCurdy
- Department of Medical PhysicsCancerCare ManitobaWinnipegManitobaCanada
- Department of Physics and AstronomyUniversity of ManitobaWinnipegManitobaCanada
- Department of RadiologyUniversity of ManitobaWinnipegManitobaCanada
| | | | - Eric Van Uytven
- Department of Medical PhysicsCancerCare ManitobaWinnipegManitobaCanada
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Eckl M, Sarria GR, Springer S, Willam M, Ruder AM, Steil V, Ehmann M, Wenz F, Fleckenstein J. Dosimetric benefits of daily treatment plan adaptation for prostate cancer stereotactic body radiotherapy. Radiat Oncol 2021; 16:145. [PMID: 34348765 PMCID: PMC8335467 DOI: 10.1186/s13014-021-01872-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/27/2021] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Hypofractionation is increasingly being applied in radiotherapy for prostate cancer, requiring higher accuracy of daily treatment deliveries than in conventional image-guided radiotherapy (IGRT). Different adaptive radiotherapy (ART) strategies were evaluated with regard to dosimetric benefits. METHODS Treatments plans for 32 patients were retrospectively generated and analyzed according to the PACE-C trial treatment scheme (40 Gy in 5 fractions). Using a previously trained cycle-generative adversarial network algorithm, synthetic CT (sCT) were generated out of five daily cone-beam CT. Dose calculation on sCT was performed for four different adaptation approaches: IGRT without adaptation, adaptation via segment aperture morphing (SAM) and segment weight optimization (ART1) or additional shape optimization (ART2) as well as a full re-optimization (ART3). Dose distributions were evaluated regarding dose-volume parameters and a penalty score. RESULTS Compared to the IGRT approach, the ART1, ART2 and ART3 approaches substantially reduced the V37Gy(bladder) and V36Gy(rectum) from a mean of 7.4cm3 and 2.0cm3 to (5.9cm3, 6.1cm3, 5.2cm3) as well as to (1.4cm3, 1.4cm3, 1.0cm3), respectively. Plan adaptation required on average 2.6 min for the ART1 approach and yielded doses to the rectum being insignificantly different from the ART2 approach. Based on an accumulation over the total patient collective, a penalty score revealed dosimetric violations reduced by 79.2%, 75.7% and 93.2% through adaptation. CONCLUSION Treatment plan adaptation was demonstrated to adequately restore relevant dose criteria on a daily basis. While for SAM adaptation approaches dosimetric benefits were realized through ensuring sufficient target coverage, a full re-optimization mainly improved OAR sparing which helps to guide the decision of when to apply which adaptation strategy.
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Affiliation(s)
- Miriam Eckl
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany.
| | - Gustavo R Sarria
- Department of Radiation Oncology, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Sandra Springer
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Marvin Willam
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Arne M Ruder
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Volker Steil
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Michael Ehmann
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Frederik Wenz
- University Medical Center Freiburg, University of Freiburg, Freiburg im Breisgau, Germany
| | - Jens Fleckenstein
- Department of Radiation Oncology, University Medical Centre Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
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Namakshenas P, Mojra A. Optimization of polyethylene glycol-based hydrogel rectal spacer for focal laser ablation of prostate peripheral zone tumor. Phys Med 2021; 89:104-113. [PMID: 34364254 DOI: 10.1016/j.ejmp.2021.07.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 07/23/2021] [Accepted: 07/28/2021] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Focal Laser ablation therapy is a technique that exposes the prostate tumor to hyperthermia ablation and eradicates cancerous cells. However, due to the excessive heating generated by laser irradiation, there is a possibility of damage to the adjacent healthy tissues. This paper through in silico study presents a novel approach to reduce collateral effects due to heating by the placement of polyethylene glycol (PEG) spacer between the rectum and tumor during laser irradiation. The PEG spacer thickness is optimized to reduce the undesired damage at common laser power used in the clinical trials. Our study also encompasses novelty by conducting the thermal analysis based on the porous structure of prostate tumor. METHODS The thermal parameters and two thermal phase lags between the temperature gradient and the heat flux, are determined by considering the vascular network of prostate tumor. The Nelder-Mead algorithm is applied to find the minimum thickness of the PEG spacer. RESULTS In the absence of the spacer, the predicted results for the laser power of 4 W, 8 W, and 12 W show that the temperature of the rectum rises up to 58.6 °C, 80.4 °C, and 101.1 °C, while through the insertion of 2.59 mm, 4 mm, and 4.9 mm of the PEG spacer, it dramatically reduces below 42 °C. CONCLUSIONS The results can be used as a guideline to ablate the prostate tumors while avoiding undesired damage to the rectal wall during laser irradiation, especially for the peripheral zone tumors.
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Affiliation(s)
- Pouya Namakshenas
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran
| | - Afsaneh Mojra
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran.
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Jaccard M, Ehrbar S, Miralbell R, Hagen T, Koutsouvelis N, Poulsen P, Rouzaud M, Tanadini-Lang S, Tsoutsou P, Guckenberger M, Zilli T. Single-fraction prostate stereotactic body radiotherapy: Dose reconstruction with electromagnetic intrafraction motion tracking. Radiother Oncol 2021; 156:145-52. [PMID: 33310011 DOI: 10.1016/j.radonc.2020.12.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/30/2020] [Accepted: 12/02/2020] [Indexed: 02/07/2023]
Abstract
PURPOSE To reconstruct the dose delivered during single-fraction urethra-sparing prostate stereotactic body radiotherapy (SBRT) accounting for intrafraction motion monitored by intraprostatic electromagnetic transponders (EMT). METHODS We analyzed data of 15 patients included in the phase I/II "ONE SHOT" trial and treated with a single fraction of 19 Gy to the planning target volume (PTV) and 17 Gy to the urethra planning risk volume. During delivery, prostate motion was tracked with implanted EMT. SBRT was interrupted when a 3-mm threshold was trespassed and corrected unless the offset was transient. Motion-encoded reconstructed (MER) plans were obtained by splitting the original plans into multiple sub-beams with isocenter shifts based on recorded EMT positions, mimicking prostate motion during treatment. We analyzed intrafraction motion and compared MER to planned doses. RESULTS The median EMT motion range (±SD) during delivery was 0.26 ± 0.09, 0.22 ± 0.14 and 0.18 ± 0.10 cm in the antero-posterior, supero-inferior, and left-right axes, respectively. Treatment interruptions were needed for 8 patients because of target motion beyond limits in the antero-posterior (n = 6) and/or supero-inferior directions (n = 4). Comparing MER vs. original plan there was a median relative dose difference of -1.9% (range, -7.9 to -1.0%) and of +0.5% (-0.3-1.7%) for PTV D98% and D2%, respectively. The clinical target volume remained sufficiently covered with a median D98% difference of -0.3% (-1.6-0.5%). Bladder and rectum dosimetric parameters showed significant differences between original and MER plans, but mostly remained within acceptable limits. CONCLUSIONS The dosimetric impact of intrafraction prostate motion was minimal for target coverage for single-fraction prostate SBRT with real-time electromagnetic tracking combined with beam gating.
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