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Klucznik KA, Ravkilde T, Skouboe S, Møller DS, Hokland SB, Keall P, Buus S, Bentzen L, Poulsen PR. Quantifying dose perturbations in high-risk prostate radiotherapy due to translational and rotational motion of prostate and pelvic lymph nodes. Med Phys 2024. [PMID: 39241224 DOI: 10.1002/mp.17366] [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: 01/16/2024] [Revised: 06/06/2024] [Accepted: 07/29/2024] [Indexed: 09/08/2024] Open
Abstract
BACKGROUND Radiotherapy of the prostate and the pelvic lymph nodes (LN) is a part of the standard of care treatment for high-risk prostate cancer. The independent translational and rotational (i.e., six-degrees-of-freedom, [6DoF]) motion of the prostate and LN target during and between fractions can perturb the dose distribution. However, no standard dose reconstruction method accounting for differential 6DoF target motion is available. PURPOSE We present a framework for monitoring motion-induced dose perturbations for two independently moving target volumes in 6DoF. The framework was used to determine the dose perturbation for the prostate and the LN target caused by differential 6DoF motion for a cohort of high-risk prostate cancer patients. As a potential first step toward real-time dose-guided high-risk prostate radiotherapy, we furthermore investigated if the dose reconstruction was fast enough for real-time application for both targets. METHODS Twenty high-risk prostate cancer patients were treated with 3-arc volumetric modulated arc therapy (VMAT). Kilovoltage intrafraction monitoring (KIM) with triggered kilovoltage (kV) images acquired every 3 throughout 7-10 fractions per patient was used for retrospective 6DoF intrafraction prostate motion estimation. The 6DoF interfraction LN motion was determined from a pelvic bone match between the planning CT and a post-treatment cone beam CT (CBCT). Using the retrospectively extracted motion, real-time 6DoF motion-including dose reconstruction was simulated using the in-house developed software DoseTracker. A data stream with the 6DoF target positions and linac parameters was broadcasted at a 3-Hz frequency to DoseTracker. In a continuous loop, DoseTracker calculated the target dose increments including the specified motion and, for comparison, without motion. The motion-induced change in D99.5% for the prostate CTV (ΔD99.5%) and in D98% for the LN CTV (ΔD98%) was calculated using the final cumulative dose of each fraction and averaged over all imaged fractions. The real-time reconstructed dose distribution of DoseTracker was benchmarked against a clinical treatment planning system (TPS) and it was investigated whether the calculation speed was fast enough to keep up with the incoming data stream. RESULTS Translational motion was largest in cranio-caudal (CC) direction (prostate: [-5.9, +8.4] mm; LN: [-9.9; +11.0] mm) and anterior-posterior (AP) direction (prostate:[-5.6; +6.9] mm; LN: [-9.6; +11.0] mm). The pitch was the largest rotation (prostate: [-22.5; +25.2] deg; LN: [-3.9; +5.5] deg). The prostate CTV ΔD99.5% was [-16.2; +2.5]% for single fractions and [-3.0; +1.7]% when averaged over all imaged fractions. The LN CTV ΔD98% was [-19.8; +1.2]% for single fractions and [-3.1; +0.9]% after averaging. Mean (Standard deviation) absolute dose errors in DoseTracker of 107.8% (Std: 1.9%) for the prostate and 105.5% (Std:1.4%) for the LN were corrected during dose reconstruction by automatically calculated normalization factors. It resulted in accurate calculation of the motion-induced dose errors with relative differences between DoseTracker and TPS dose calculations of -0.1% (Std: 0.5%) (prostate CTV ΔD99.5%) and -0.2% (Std: 0.5%) (LN CTV ΔD98%). The DoseTracker calculation was fast enough to keep up with the incoming inputs for all but two out of 107 184 dose calculations. CONCLUSION Using the developed framework for dose perturbation monitoring, we found that the differential 6DoF target motion caused substantial dose perturbation for individual fractions, which largely averaged out after several fractions. The framework was shown to provide reliable dose calculations and a sufficiently high-dose reconstruction speed to be applicable in real-time.
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Affiliation(s)
- Karolina A Klucznik
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Thomas Ravkilde
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Simon Skouboe
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Ditte S Møller
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Paul Keall
- ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, Australia
| | - Simon Buus
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | - Lise Bentzen
- Department of Oncology, Vejle Hospital, University of Southern Denmark, Vejle, Denmark
| | - Per R Poulsen
- Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
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Persson E, Goodwin E, Eiben B, Wetscherek A, Nill S, Oelfke U. Real-time motion-including dose estimation of simulated multi-leaf collimator-tracked magnetic resonance-guided radiotherapy. Med Phys 2024; 51:2221-2229. [PMID: 37898109 DOI: 10.1002/mp.16798] [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: 04/26/2023] [Revised: 09/28/2023] [Accepted: 09/28/2023] [Indexed: 10/30/2023] Open
Abstract
BACKGROUND Real-time dose estimation is a key-prerequisite to enable online intra-fraction treatment adaptation in magnetic resonance (MR)-guided radiotherapy (MRgRT). It is an essential component for the assessment of the dosimetric benefits and risks of online adaptive treatments, such as multi-leaf collimator (MLC)-tracking. PURPOSE We present a proof-of-concept for a software workflow for real-time dose estimation of MR-guided adaptive radiotherapy based on real-time data-streams of the linac delivery parameters and target positions. METHODS A software workflow, combining our in-house motion management software DynaTrack, a real-time dose calculation engine that connects to a research version of the treatment planning software (TPS) Monaco (v.6.09.00, Elekta AB, Stockholm, Sweden) was developed and evaluated. MR-guided treatment delivery on the Elekta Unity MR-linac was simulated with and without MLC-tracking for three prostate patients, previously treated on the Elekta Unity MR-linac (36.25 Gy/five fractions). Three motion scenarios were used: no motion, regular motion, and erratic prostate motion. Accumulated monitor units (MUs), centre of mass target position and MLC-leaf positions, were forwarded from DynaTrack at a rate of 25 Hz to a Monte Carlo (MC) based dose calculation engine which utilises the research GPUMCD-library (Elekta AB, Stockholm, Sweden). A rigid isocentre shift derived from the selected motion scenarios was applied to a bulk density-assigned session MR-image. The respective electron density used for treatment planning was accessed through the research Monaco TPS. The software workflow including the online dose reconstruction was validated against offline dose reconstructions. Our investigation showed that MC-based real-time dose calculations that account for all linac states (including MUs, MLC positions and target position) were infeasible, hence states were randomly sampled and used for calculation as follows; Once a new linac state was received, a dose calculation with 106 photons was started. Linac states that arrived during the time of the ongoing calculation were put into a queue. After completion of the ongoing calculation, one new linac state was randomly picked from the queue and assigned the MU accumulated from the previous state until the last sample in the queue. The queue was emptied, and the process repeated throughout treatment simulation. RESULTS On average 27% (23%-30%) of received samples were used in the real-time calculation, corresponding to a calculation time for one linac state of 148 ms. Median gamma pass rate (2%/3 mm local) was 100.0% (99.9%-100%) within the PTV volume and 99.1% (90.1%-99.4.0%) with a 15% dose cut off. Differences in PTVDmean , CTVDmean , RectumD2% , and BladderD2% (offline-online, % of prescribed dose) were below 0.64%. Beam-by-beam comparisons showed deviations below 0.07 Gy. Repeated simulations resulted in standard deviations below 0.31% and 0.12 Gy for the investigated volume and dose criteria respectively. CONCLUSIONS Real-time dose estimation was successfully performed using the developed software workflow for different prostate motion traces with and without MLC-tracking. Negligible dosimetric differences were seen when comparing online and offline reconstructed dose, enabling online intra-fraction treatment decisions based on estimates of the delivered dose.
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Affiliation(s)
- Emilia Persson
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
| | - Edmund Goodwin
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
| | - Björn Eiben
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
| | - Andreas Wetscherek
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
| | - Simeon Nill
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
| | - Uwe Oelfke
- Joint Department of Physics, The Royal Marsden Hospital and The Institute of Cancer Research, Sutton, UK
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Cao Z, Gao X, Liu G, Pei Y. Effect of metal implants and metal artifacts on back-projected two-dimensional entrance fluence determined by EPID dosimetry. J Appl Clin Med Phys 2023; 24:e14115. [PMID: 37573570 PMCID: PMC10647983 DOI: 10.1002/acm2.14115] [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: 03/28/2023] [Revised: 06/30/2023] [Accepted: 07/25/2023] [Indexed: 08/15/2023] Open
Abstract
PURPOSE To evaluate the errors caused by metal implants and metal artifacts in the two-dimensional entrance fluences reconstructed using the back-projection algorithm based on electronic portal imaging device (EPID) images. METHODS The EPID in the Varian VitalBeam accelerator was used to acquire portal dose images (PDIs), and then commercial EPID dosimetry software was employed to reconstruct the two-dimensional entrance fluences based on computed tomography (CT) images of the head phantoms containing interchangeable metal-free/titanium/aluminum round bars. The metal-induced errors in the two-dimensional entrance fluences were evaluated by comparing the γ results and the pixel value errors in the metal-affected regions. We obtained metal-artifact-free CT images by replacing the voxel values of non-metal inserts with those of metal inserts in metal-free CT images to evaluate the metal-artifact-induced errors. RESULTS The γ passing rates (versus PDIs obtained without a phantom in the beam field (PDIair ), 2%/2 mm) for the back-projected two-dimensional entrance fluences of phantoms containing titanium or aluminum (BPTi /BPAl ) were reduced from 92.4% to 90.5% and 90.6%, respectively, relative to the metal-free phantom (BPmetal-free ). Titanium causes more severe metal artifacts in CT images than aluminum, and its removal resulted in a 0.0022 CU (median) reduction in the pixel value of BPTi artifact-free relative to BPTi in the metal-affected region. Moreover, the mean absolute error (MAE) and root mean square error (RMSE) decreased from 0.0050 CU and 0.0063 CU to 0.0034 CU and 0.0040 CU, respectively (vs. BPmetal-free ). CONCLUSION Metal implants increase the errors in back-projected two-dimensional entrance fluences, and metals with higher electron densities cause more errors. For high-electron-density metal implants that produce severe metal artifacts (e.g., titanium), removing metal artifacts from the CT images can improve the accuracy of the two-dimensional entrance fluences reconstructed by back-projection algorithms.
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Affiliation(s)
- Zheng Cao
- National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefeiChina
- Hematology & Oncology DepartmentHefei First People's HospitalHefeiChina
| | - Xiang Gao
- Hematology & Oncology DepartmentHefei First People's HospitalHefeiChina
| | - Gongfa Liu
- National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefeiChina
| | - Yuanji Pei
- National Synchrotron Radiation LaboratoryUniversity of Science and Technology of ChinaHefeiChina
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Peng H, Zhang J, Xu N, Zhou Y, Tan H, Ren T. Fan beam CT-guided online adaptive external radiotherapy of uterine cervical cancer: a dosimetric evaluation. BMC Cancer 2023; 23:588. [PMID: 37365516 DOI: 10.1186/s12885-023-11089-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 06/20/2023] [Indexed: 06/28/2023] Open
Abstract
PURPOSE To discuss the dosimetric advantages and reliability of the accurate delivery of online adaptive radiotherapy(online ART) for uterine cervical cancer(UCC). METHODS AND MATERIALS Six UCC patients were enrolled in this study. 95% of the planning target volume (PTV) reached 100% of the prescription dose (50.4 Gy/28fractions/6weeks) was required. The patients were scanned with uRT-Linac 506c KV-FBCT then the target volume (TV) and organs at risk (OARs) were delineated by doctors. The dosimeters designed and obtained a routine plan (Plan0). KV-FBCT was used for image guidance before subsequent fractional treatment. The online ART was processed after registration, which acquired a virtual nonadaptive radiotherapy plan (VPlan) and an adaptive plan (APlan). VPlan was the direct calculation of Plan0 on the fractional image, while APlan required adaptive optimization and calculation. In vivo dose monitoring and three-dimensional dose reconstruction were required during the implementation of APlan. RESULTS The inter-fractional volumes of the bladder and rectum changed greatly among the treatments. These changes influenced the primary gross tumor volume (GTVp) and the position deviation of GTVp and PTV and positively affected the prescription dose coverage of TV. GTVp decreased gradually along with dose accumulation. The Dmax, D98, D95, D50, and D2 of APlan were superior to those of VPlan in target dose distribution. APlan had good conformal index, homogeneity index and target coverage. The rectum V40 and Dmax, bladder V40, the small bowel V40 and Dmax of APlan were better than that of VPlan. The APlan's fractional mean γ passing rate was significantly higher than the international standard and the mean γ passing rate of all cases after the three-dimensional reconstruction was higher than 97.0%. CONCLUSION Online ART in external radiotherapy of UCC significantly improved the dose distribution and can become an ideal technology to achieve individualized precise radiotherapy.
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Affiliation(s)
- Haibo Peng
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
- Key Clinical Specialty of Sichuan Province (Oncology Department), The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
- Clinical Medical School, Chengdu Medical College, Chengdu, 610500, China
| | - Jie Zhang
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
- Key Clinical Specialty of Sichuan Province (Oncology Department), The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
- Clinical Medical School, Chengdu Medical College, Chengdu, 610500, China
| | - Ningyue Xu
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
| | - Yangang Zhou
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
| | - Huigang Tan
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China
| | - Tao Ren
- Oncology Department, The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China.
- Key Clinical Specialty of Sichuan Province (Oncology Department), The First Affiliated Hospital of Chengdu Medical College, Chengdu, 610500, China.
- Clinical Medical School, Chengdu Medical College, Chengdu, 610500, China.
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Qiu Z, Olberg S, den Hertog D, Ajdari A, Bortfeld T, Pursley J. Online adaptive planning methods for intensity-modulated radiotherapy. Phys Med Biol 2023; 68:10.1088/1361-6560/accdb2. [PMID: 37068488 PMCID: PMC10637515 DOI: 10.1088/1361-6560/accdb2] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 04/17/2023] [Indexed: 04/19/2023]
Abstract
Online adaptive radiation therapy aims at adapting a patient's treatment plan to their current anatomy to account for inter-fraction variations before daily treatment delivery. As this process needs to be accomplished while the patient is immobilized on the treatment couch, it requires time-efficient adaptive planning methods to generate a quality daily treatment plan rapidly. The conventional planning methods do not meet the time requirement of online adaptive radiation therapy because they often involve excessive human intervention, significantly prolonging the planning phase. This article reviews the planning strategies employed by current commercial online adaptive radiation therapy systems, research on online adaptive planning, and artificial intelligence's potential application to online adaptive planning.
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Affiliation(s)
- Zihang Qiu
- Department of Business Analytics, University of Amsterdam, The Netherlands
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Sven Olberg
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Dick den Hertog
- Department of Business Analytics, University of Amsterdam, The Netherlands
| | - Ali Ajdari
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Thomas Bortfeld
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Jennifer Pursley
- Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, United States of America
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Sengupta C, Skouboe S, Ravkilde T, Poulsen PR, Nguyen DT, Greer PB, Moodie T, Hardcastle N, Hayden AJ, Turner S, Siva S, Tai KH, Martin J, Booth JT, O'Brien R, Keall PJ. The dosimetric error due to uncorrected tumor rotation during real-time adaptive prostate stereotactic body radiation therapy. Med Phys 2023; 50:20-29. [PMID: 36354288 PMCID: PMC10099881 DOI: 10.1002/mp.16094] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 10/06/2022] [Accepted: 10/27/2022] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND During prostate stereotactic body radiation therapy (SBRT), prostate tumor translational motion may deteriorate the planned dose distribution. Most of the major advances in motion management to date have focused on correcting this one aspect of the tumor motion, translation. However, large prostate rotation up to 30° has been measured. As the technological innovation evolves toward delivering increasingly precise radiotherapy, it is important to quantify the clinical benefit of translational and rotational motion correction over translational motion correction alone. PURPOSE The purpose of this work was to quantify the dosimetric impact of intrafractional dynamic rotation of the prostate measured with a six degrees-of-freedom tumor motion monitoring technology. METHODS The delivered dose was reconstructed including (a) translational and rotational motion and (b) only translational motion of the tumor for 32 prostate cancer patients recruited on a 5-fraction prostate SBRT clinical trial. Patients on the trial received 7.25 Gy in a treatment fraction. A 5 mm clinical target volume (CTV) to planning target volume (PTV) margin was applied in all directions except the posterior direction where a 3 mm expansion was used. Prostate intrafractional translational motion was managed using a gating strategy, and any translation above the gating threshold was corrected by applying an equivalent couch shift. The residual translational motion is denoted as T r e s $T_{res}$ . Prostate intrafractional rotational motion R u n c o r r $R_{uncorr}$ was recorded but not corrected. The dose differences from the planned dose due to T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ , ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and due to T r e s $T_{res}$ alone, ΔD( T r e s $T_{res}$ ), were then determined for CTV D98, PTV D95, bladder V6Gy, and rectum V6Gy. The residual dose error due to uncorrected rotation, R u n c o r r $R_{uncorr}$ was then quantified: Δ D R e s i d u a l $\Delta D_{Residual}$ = ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) - ΔD( T res ${T}_{\textit{res}}$ ). RESULTS Fractional data analysis shows that the dose differences from the plan (both ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and ΔD( T r e s $T_{res}$ )) for CTV D98 was less than 5% in all treatment fractions. ΔD( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) was larger than 5% in one fraction for PTV D95, in one fraction for bladder V6Gy, and in five fractions for rectum V6Gy. Uncorrected rotation, R u n c o r r $R_{uncorr}$ induced residual dose error, Δ D R e s i d u a l $\Delta D_{Residual}$ , resulted in less dose to CTV and PTV in 43% and 59% treatment fractions, respectively, and more dose to bladder and rectum in 51% and 53% treatment fractions, respectively. The cumulative dose over five fractions, ∑D( T r e s $T_{res}$ + R u n c o r r $R_{uncorr}$ ) and ∑D( T r e s $T_{res}$ ), was always within 5% of the planned dose for all four structures for every patient. CONCLUSIONS The dosimetric impact of tumor rotation on a large prostate cancer patient cohort was quantified in this study. These results suggest that the standard 3-5 mm CTV-PTV margin was sufficient to account for the intrafraction prostate rotation observed for this cohort of patients, provided an appropriate gating threshold was applied to correct for translational motion. Residual dose errors due to uncorrected prostate rotation were small in magnitude, which may be corrected using different treatment adaptation strategies to further improve the dosimetric accuracy.
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Affiliation(s)
- Chandrima Sengupta
- ACRF Image X Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Simon Skouboe
- Danish Center for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | - Thomas Ravkilde
- Department of Oncology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Doan Trang Nguyen
- ACRF Image X Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Peter B Greer
- Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales, Australia
| | - Trevor Moodie
- Crown Princess Mary Cancer Center, Sydney, New South Wales, Australia
| | | | - Amy J Hayden
- Crown Princess Mary Cancer Center, Sydney, New South Wales, Australia
| | - Sandra Turner
- Crown Princess Mary Cancer Center, Sydney, New South Wales, Australia
| | - Shankar Siva
- Peter MacCallum Cancer Center, Melbourne, Victoria, Australia
| | - Keen-Hun Tai
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jarad Martin
- Department of Radiation Oncology, Calvary Mater Newcastle, Waratah, New South Wales, Australia
| | - Jeremy T Booth
- Northern Sydney Cancer Center, Royal North Shore Hospital, Sydney, New South Wales, Australia
| | - Ricky O'Brien
- ACRF Image X Institute, University of Sydney, Sydney, New South Wales, Australia
| | - Paul J Keall
- ACRF Image X Institute, University of Sydney, Sydney, New South Wales, Australia
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Hewson EA, Nguyen DT, Le A, Booth JT, Keall PJ, Mejnertsen L. Optimising multi-target multileaf collimator tracking using real-time dose for locally advanced prostate cancer patients. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac8967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 08/12/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Objective. The accuracy of radiotherapy for patients with locally advanced cancer is compromised by independent motion of multiple targets. To date, MLC tracking approaches have used 2D geometric optimisation where the MLC aperture shape is simply translated to correspond to the target’s motion, which results in sub-optimal delivered dose. To address this limitation, a dose-optimised multi-target MLC tracking method was developed and evaluated through simulated locally advanced prostate cancer treatments. Approach. A dose-optimised multi-target tracking algorithm that adapts the MLC aperture to minimise 3D dosimetric error was developed for moving prostate and static lymph node targets. A fast dose calculation algorithm accumulated the planned dose to the prostate and lymph node volumes during treatment in real time, and the MLC apertures were recalculated to minimise the difference between the delivered and planned dose with the included motion. Dose-optimised tracking was evaluated by simulating five locally advanced prostate plans and three prostate motion traces with a relative interfraction displacement. The same simulations were performed using geometric-optimised tracking and no tracking. The dose-optimised, geometric-optimised, and no tracking results were compared with the planned doses using a 2%/2 mm γ criterion. Main results. The mean dosimetric error was lowest for dose-optimised MLC tracking, with γ-failure rates of 12% ± 8.5% for the prostate and 2.2% ± 3.2% for the nodes. The γ-failure rates for geometric-optimised MLC tracking were 23% ± 12% for the prostate and 3.6% ± 2.5% for the nodes. When no tracking was used, the γ-failure rates were 37% ± 28% for the prostate and 24% ± 3.2% for the nodes. Significance. This study developed a dose-optimised multi-target MLC tracking method that minimises the difference between the planned and delivered doses in the presence of intrafraction motion. When applied to locally advanced prostate cancer, dose-optimised tracking showed smaller errors than geometric-optimised tracking and no tracking for both the prostate and nodes.
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Ehrbar S, Braga Käser S, Chamberlain M, Krayenbühl J, Wilke L, Mayinger M, Garcia Schüler H, Guckenberger M, Andratschke N, Tanadini-Lang S. MR-guided beam gating: Residual motion, gating efficiency and dose reconstruction for stereotactic treatments of the liver and lung. Radiother Oncol 2022; 174:101-108. [PMID: 35839937 DOI: 10.1016/j.radonc.2022.07.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 06/01/2022] [Accepted: 07/07/2022] [Indexed: 01/10/2023]
Abstract
PURPOSE This study aims to investigate the efficiency and the geometric as well as the dosimetric benefit of magnetic-resonance guided beam gating for stereotactic treatments in moving organs. METHOD Patients treated with MR-guided (MRIdian system) SBRT for lung (n = 10) and liver (n = 10) targets were analyzed. Breath-hold gating was performed based on lesion tracking in sagittal cine MRI images. The target offset from the geometric center of the gating window with and without gating was evaluated. A dose reconstruction workflow based on convolution of these 2D position-probability maps and the daily 3D dose distribution was used to estimate the daily delivered dose including motion. The dose to the clinical target volume (CTV) and to a 2-cm ring structure around the planning target volume were evaluated. RESULTS The applied gating protocol resulted in a mean (±standard deviation) gating efficiency of 55%±16%. Over all patients, the mean target offset (2D-root-mean-square error) was 8.3 ± 4.3 mm, which reduced to 2.4 ± 0.6 mm during gating. The dose reconstruction showed a mean deviation in CTV coverage (D95) from the static plans of -1.7%±1.8% with gating and -12.0%±8.4% if no gating would have been used. The mean dose (Dmean) in the ring structure, with respect to the static plans, showed mean deviations of -0.1%±0.3% with gating and -1.6%±1.8% without gating. CONCLUSION The MRIdian system enables gating based on the inner anatomy and the implemented dose reconstruction workflow demonstrated geometric robust delivery of the planned radiation doses.
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Affiliation(s)
- Stefanie Ehrbar
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland.
| | - Sarah Braga Käser
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Madalyne Chamberlain
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Jérôme Krayenbühl
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Lotte Wilke
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Michael Mayinger
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Helena Garcia Schüler
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Matthias Guckenberger
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Nicolaus Andratschke
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
| | - Stephanie Tanadini-Lang
- Department of Radiation Oncology, University Hospital Zürich and University of Zürich, Zürich, Switzerland
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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] [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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