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Uijtewaal P, Borman P, Cote B, LeChasseur Y, Therriault-Proulx F, Flores R, Smith S, Koenig G, Raaymakers B, Fast M. Performance characterization of a novel hybrid dosimetry insert for simultaneous spatial, temporal, and motion-included dosimetry for MR-linac. Med Phys 2024; 51:2983-2997. [PMID: 38088939 DOI: 10.1002/mp.16870] [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: 07/21/2023] [Revised: 11/13/2023] [Accepted: 11/17/2023] [Indexed: 04/05/2024] Open
Abstract
BACKGROUND Several (online) adaptive radiotherapy procedures are available to maximize healthy tissue sparing in the presence of inter/intrafractional motion during stereotactic body radiotherapy (SBRT) on an MR-linac. The increased treatment complexity and the motion-delivery interplay during these treatments require MR-compatible motion phantoms with time-resolved dosimeters to validate end-to-end workflows. This is not possible with currently available phantoms. PURPOSE Here, we demonstrate a new commercial hybrid film-scintillator cassette, combining high spatial resolution radiochromic film with four time-resolved plastic scintillator dosimeters (PSDs) in an MRI-compatible motion phantom. METHODS First, the PSD's performance for consistency, dose linearity, and pulse repetition frequency (PRF) dependence was evaluated using an RW3 solid water slab phantom. We then demonstrated the MRI4D scintillator cassette's suitability for time-resolved and motion-included quality assurance for adapt-to-shape (ATS), trailing, gating, and multileaf collimator (MLC) tracking adaptations on a 1.5 T MR-linac. To do this, the cassette was inserted into the Quasar MRI4D phantom, which we used statically or programmed with artificial and patient-derived motion. Simultaneously with dose measurements, the beam-gating latency was estimated from the time difference between the target entering/leaving the gating window and the beam-on/off times derived from the time-resolved dose measurements. RESULTS Experiments revealed excellent detector consistency (standard deviation ≤ $\le$ 0.6%), dose linearity (R2 = 1), and only very low PRF dependence ( ≤ $\le$ 0.4%). The dosimetry cassette demonstrated a near-perfect agreement during an ATS workflow between the time-resolved PSD and treatment planning system (TPS) dose (0%-2%). The high spatial resolution film measurements confirmed this with a 1%/1-mm local gamma pass-rate of 90%. When trailing patient-derived prostate motion for a prostate SBRT delivery, the time-resolved cassette measurements demonstrated how trailing mitigated the motion-induced dose reductions from 1%-17% to 1%-2% compared to TPS dose. The cassette's simultaneously measured spatial dose distribution highlighted the dosimetric gain of trailing by improving the 3%/3-mm local gamma pass-rates from 80% to 97% compared to the static dose. Similarly, the cassette demonstrated the benefit of real-time adaptations when compensating patient-derived respiratory motion by showing how the TPS dose was restored from 2%-56% to 0%-12% (gating) and 1%-26% to 1%-7% (MLC tracking) differences. Larger differences are explainable by TPS-PSD coregistration uncertainty combined with a steep dose gradient outside the PTV. The cassette also demonstrated how the spatial dose distributions were drastically improved by the real-time adaptations with 1%/1-mm local gamma pass-rates that were increased from 8 to 79% (gating) and from 35 to 89% (MLC tracking). The cassette-determined beam-gating latency agreed within ≤ $\le$ 12 ms with the ground truth latency measurement. Film and PSD dose agreed well for most cases (differences relative to TPS dose < $<$ 4%), while film-PSD coregistration uncertainty caused relative differences of 5%-8%. CONCLUSIONS This study demonstrates the excellent suitability of a new commercial hybrid film-scintillator cassette for simultaneous spatial, temporal, and motion-included dosimetry.
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Affiliation(s)
- Prescilla Uijtewaal
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Pim Borman
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
| | | | | | | | | | | | | | | | - Martin Fast
- Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands
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Uijtewaal P, Côté B, Foppen T, de Vries W, Woodings S, Borman P, Lambert-Girard S, Therriault-Proulx F, Raaymakers B, Fast M. Performance of the HYPERSCINT scintillation dosimetry research platform for the 1.5 T MR-linac. Phys Med Biol 2023; 68. [PMID: 36638536 DOI: 10.1088/1361-6560/acb30c] [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: 10/05/2022] [Accepted: 01/13/2023] [Indexed: 01/15/2023]
Abstract
Objective.Adaptive radiotherapy techniques available on the MR-linac, such as daily plan adaptation, gating, and dynamic tracking, require versatile dosimetric detectors to validate end-to-end workflows. Plastic scintillator detectors (PSDs) offer great potential with features including: water equivalency, MRI-compatibility, and time-resolved dose measurements. Here, we characterize the performance of the HYPERSCINT RP-200 PSD (MedScint, Quebec, CA) in a 1.5 T MR-linac, and we demonstrate its suitability for dosimetry, including in a moving target.Approach.Standard techniques of detector testing were performed using a Beamscan water tank (PTW, Freiburg, DE) and compared to microDiamond (PTW, Freiburg, DE) readings. Orientation dependency was tested using the same phantom. An RW3 solid water phantom was used to evaluate detector consistency, dose linearity, and dose rate dependence. To determine the sensitivity to motion and to MRI scanning, the Quasar MRI4Dphantom (Modus, London, ON) was used statically or with sinusoidal motion (A= 10 mm,T= 4 s) to compare PSD and Semiflex ionization chamber (PTW, Freiburg, DE) readings. Conformal beams from gantry 0° and 90° were used as well as a 15-beam 8 × 7.5 Gy lung IMRT plan.Main results.Measured profiles, PDD curves and field-size dependence were consistent with the microDiamond readings with differences well within our clinical tolerances. The angular dependence gave variations up to 0.8% when not irradiating directly from behind the scintillation point. Experiments revealed excellent detector consistency between repeated measurements (SD = 0.06%), near-perfect dose linearity (R2= 1) and a dose rate dependence <0.3%. Dosimetric effects of MRI scanning (≤0.3%) and motion (≤1.3%) were minimal. Measurements were consistent with the Semiflex (differences ≤1%), and with the treatment planning system with differences of 0.8% and 0.4%, with and without motion.Significance.This study demonstrates the suitability of the HYPERSCINT PSD for accurate time-resolved dosimetry measurements in the 1.5 T MR-linac, including during MR scanning and target motion.
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Affiliation(s)
- Prescilla Uijtewaal
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Benjamin Côté
- MedScint, 1405 Bd du Parc Technologique, Québec, QC G1P 4P5, Canada
| | - Thomas Foppen
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Wilfred de Vries
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Simon Woodings
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Pim Borman
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | | | | | - Bas Raaymakers
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
| | - Martin Fast
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
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3
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DI Franco R, Borzillo V, Alberti D, Ametrano G, Petito A, Coppolaro A, Tarantino I, Rossetti S, Pignata S, Iovane G, Perdonà S, Quarto G, Grimaldi G, Izzo A, Castaldo L, Muscariello R, Serra M, Facchini G, Muto P. Acute Toxicity in Hypofractionated/Stereotactic Prostate Radiotherapy of Elderly Patients: Use of the Image-guided Radio Therapy (IGRT) Clarity System. In Vivo 2021; 35:1849-1856. [PMID: 33910872 DOI: 10.21873/invivo.12447] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/17/2021] [Accepted: 03/25/2021] [Indexed: 11/10/2022]
Abstract
BACKGROUND The use of intra-fractional monitoring and correction of prostate position with the Image Guided Radio Therapy (IGRT) system can increase the spatial accuracy of dose delivery. Clarity is a system used for intrafraction prostate-motion management, it provides a real-time visualization of prostate with a transperineal ultrasound. The aim of this study was to evaluate the use of Clarity-IGRT on proper intrafraction alignment and monitoring, its impact on Planning Tumor Volume margin and on urinary and rectal toxicity in elderly patients not eligible for surgery. PATIENTS AND METHODS Twenty-five elderly prostate cancer patients, median age=75 years (range=75-90 years) were treated with Volumetric Radiotherapy and Clarity-IGRT using 3 different schemes: A) 64.5/72 Gray (Gy) in 30 fractions on prostate and seminal vesicles (6 patients); B) 35 Gy in 5 fractions on prostate and seminal vesicles (12 patients); C): 35 Gy in 5 fractions on prostate (7 patients). Ultrasound identification of the overlapped structures to the detected ones during simulation has been used in each session. A specific software calculates direction and entity of necessary shift to obtain the perfect match. The average misalignment in the three-dimensional space has been determined and shown in a box-plot. RESULTS All patients completed treatment with mild-moderate toxicity. During treatment, genitourinary toxicity was 32% Grade 1; 4% Grade 2, rectal was 4% Grade 1. At follow-up of 3 months, genitourinary toxicity was 20% Grade 1; 4% Grade 2, rectal toxicity was 4% Grade 2. At follow-up of 6 months, genitourinary toxicity was 4% Grade 1; 4% Grade 2. Rectal toxicity was 4% Grade 2. CONCLUSION Radiotherapy with the Clarity System allows a reduction of PTV margins, the amount of fractions can be reduced increasing the total dose, not exacerbating urinary and rectal toxicity with greater patient's compliance.
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Affiliation(s)
- Rossella DI Franco
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy;
| | - Valentina Borzillo
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Domingo Alberti
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Gianluca Ametrano
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Angela Petito
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Andrea Coppolaro
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Ilaria Tarantino
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Sabrina Rossetti
- Departmental Unit Of Clinical and Experimental Uro-Andrologic Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Sandro Pignata
- Departmental Unit Of Clinical and Experimental Uro-Andrologic Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Gelsomina Iovane
- Departmental Unit Of Clinical and Experimental Uro-Andrologic Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Sisto Perdonà
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Giuseppe Quarto
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Giovanni Grimaldi
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Alessandro Izzo
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Luigi Castaldo
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Raffaele Muscariello
- Uro-Gynecological Department, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Marcello Serra
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
| | - Gaetano Facchini
- Department of Hospital Medicine, Unit of Medical Oncology, ASL Napoli 2 Nord, "S.M. delle Grazie" Hospital, Pozzuoli, Italy
| | - Paolo Muto
- Department of Radiation Oncology, Istituto Nazionale Tumori - IRCCS - Fondazione G. Pascale, Naples, Italy
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4
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Keall PJ, Sawant A, Berbeco RI, Booth JT, Cho B, Cerviño LI, Cirino E, Dieterich S, Fast MF, Greer PB, Munck Af Rosenschöld P, Parikh PJ, Poulsen PR, Santanam L, Sherouse GW, Shi J, Stathakis S. AAPM Task Group 264: The safe clinical implementation of MLC tracking in radiotherapy. Med Phys 2021; 48:e44-e64. [PMID: 33260251 DOI: 10.1002/mp.14625] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/11/2020] [Accepted: 11/18/2020] [Indexed: 12/25/2022] Open
Abstract
The era of real-time radiotherapy is upon us. Robotic and gimbaled linac tracking are clinically established technologies with the clinical realization of couch tracking in development. Multileaf collimators (MLCs) are a standard equipment for most cancer radiotherapy systems, and therefore MLC tracking is a potentially widely available technology. MLC tracking has been the subject of theoretical and experimental research for decades and was first implemented for patient treatments in 2013. The AAPM Task Group 264 Safe Clinical Implementation of MLC Tracking in Radiotherapy Report was charged to proactively provide the broader radiation oncology community with (a) clinical implementation guidelines including hardware, software, and clinical indications for use, (b) commissioning and quality assurance recommendations based on early user experience, as well as guidelines on Failure Mode and Effects Analysis, and (c) a discussion of potential future developments. The deliverables from this report include: an explanation of MLC tracking and its historical development; terms and definitions relevant to MLC tracking; the clinical benefit of, clinical experience with and clinical implementation guidelines for MLC tracking; quality assurance guidelines, including example quality assurance worksheets; a clinical decision pathway, future outlook and overall recommendations.
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Affiliation(s)
- Paul J Keall
- ACRF Image X Institute, The University of Sydney Faculty of Medicine and Health, Sydney, NSW, 2006, Australia
| | - Amit Sawant
- Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Ross I Berbeco
- Radiation Oncology, Brigham and Women's Hospital, Boston, MA, 02115, USA
| | - Jeremy T Booth
- Radiation Oncology, Royal North Shore Hospital, St Leonards, 2065, NSW, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, 2006, Australia
| | - Byungchul Cho
- Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, 138-736, Republic of Korea
| | - Laura I Cerviño
- Radiation Medicine & Applied Sciences, Radiation Oncology PET/CT Center, UC San Diego, LA Jolla, CA, 92093-0865, USA.,Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 10065-6007, USA
| | - Eileen Cirino
- Lahey Health and Medical Center, Burlington, MA, 01805, USA
| | - Sonja Dieterich
- Department of Radiation Oncology, UC Davis Medical Center, Sacramento, CA, 95618, USA
| | - Martin F Fast
- Department of Radiotherapy, University Medical Center Utrecht, 3584 CX, Utrecht, The Netherlands
| | - Peter B Greer
- Calvary Mater Newcastle, Newcastle, NSW, 2310, Australia
| | - Per Munck Af Rosenschöld
- Radiation Physics, Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden
| | - Parag J Parikh
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Department of Radiation Oncology, Henry Ford Hospital, Detroit, MI, 48202, USA
| | - Per Rugaard Poulsen
- Department of Oncology and Danish Center for Particle Therapy, Aarhus University Hospital, 8200, Aarhus, Denmark
| | - Lakshmi Santanam
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, 63110, USA.,Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, 10065-6007, USA
| | | | - Jie Shi
- Sun Nuclear Corp, Melbourne, FL, 32940, USA
| | - Sotirios Stathakis
- University of Texas Health San Antonio Cancer Center, San Antonio, TX, 78229, USA
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5
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Skouboe S, Poulsen PR, Muurholm CG, Worm E, Hansen R, Høyer M, Ravkilde T. Simulated real‐time dose reconstruction for moving tumors in stereotactic liver radiotherapy. Med Phys 2019; 46:4738-4748. [DOI: 10.1002/mp.13792] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Revised: 08/13/2019] [Accepted: 08/19/2019] [Indexed: 12/21/2022] Open
Affiliation(s)
- Simon Skouboe
- Department of Oncology Aarhus University Hospital Aarhus N 8200Denmark
| | - Per Rugaard Poulsen
- Department of Oncology Aarhus University Hospital Aarhus N 8200Denmark
- Danish Center for Particle Therapy Aarhus University Hospital Aarhus N 8200 Denmark
| | | | - Esben Worm
- Department of Medical Physics Aarhus University Hospital Aarhus N 8200Denmark
| | - Rune Hansen
- Department of Medical Physics Aarhus University Hospital Aarhus N 8200Denmark
| | - Morten Høyer
- Danish Center for Particle Therapy Aarhus University Hospital Aarhus N 8200 Denmark
| | - Thomas Ravkilde
- Department of Medical Physics Aarhus University Hospital Aarhus N 8200Denmark
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Pham J, Harris W, Sun W, Yang Z, Yin FF, Ren L. Predicting real-time 3D deformation field maps (DFM) based on volumetric cine MRI (VC-MRI) and artificial neural networks for on-board 4D target tracking: a feasibility study. Phys Med Biol 2019; 64:165016. [PMID: 31344693 PMCID: PMC6734921 DOI: 10.1088/1361-6560/ab359a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
To predict real-time 3D deformation field maps (DFMs) using Volumetric Cine MRI (VC-MRI) and adaptive boosting and multi-layer perceptron neural network (ADMLP-NN) for 4D target tracking. One phase of a prior 4D-MRI is set as the prior phase, MRIprior. Principal component analysis (PCA) is used to extract three major respiratory deformation modes from the DFMs generated between the prior and remaining phases. VC-MRI at each time-step is considered a deformation of MRIprior, where the DFM is represented as a weighted linear combination of the PCA components. The PCA weightings are solved by minimizing the differences between on-board 2D cine MRI and its corresponding VC-MRI slice. The PCA weightings solved during the initial training period are used to train an ADMLP-NN to predict PCA weightings ahead of time during the prediction period. The predicted PCA weightings are used to build predicted 3D DFM and ultimately, predicted VC-MRIs for 4D target tracking. The method was evaluated using a 4D computerized phantom (XCAT) with patient breathing curves and MRI data from a real liver cancer patient. Effects of breathing amplitude change and ADMLP-NN parameter variations were assessed. The accuracy of the PCA curve prediction was evaluated. The predicted real-time 3D tumor was evaluated against the ground-truth using volume dice coefficient (VDC), center-of-mass-shift (COMS), and target tracking errors. For the XCAT study, the average VDC and COMS for the predicted tumor were 0.92 ± 0.02 and 1.06 ± 0.40 mm, respectively, across all predicted time-steps. The correlation coefficients between predicted and actual PCA curves generated through VC-MRI estimation for the 1st/2nd principal components were 0.98/0.89 and 0.99/0.57 in the SI and AP directions, respectively. The optimal number of input neurons, hidden neurons, and MLP-NN for ADMLP-NN PCA weighting coefficient prediction were determined to be 7, 4, and 10, respectively. The optimal cost function threshold was determined to be 0.05. PCA weighting coefficient and VC-MRI accuracy was reduced for increased prediction-step size. Accurate PCA weighting coefficient prediction correlated with accurate VC-MRI prediction. For the patient study, the predicted 4D tumor tracking errors in superior-inferior, anterior-posterior and lateral directions were 0.50 ± 0.47 mm, 0.40 ± 0.55 mm, and 0.28 ± 0.12 mm, respectively. Preliminary studies demonstrated the feasibility to use VC-MRI and artificial neural networks to predict real-time 3D DFMs of the tumor for 4D target tracking.
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Affiliation(s)
- Jonathan Pham
- Medical Physics Graduate Program, Duke University, 2424 Erwin Road Suite 101, Durham, NC 27705, United States of America
| | - Wendy Harris
- Department of Radiation Oncology, Perelman Center for Advanced Medicine, 3400 Civic Boulevard Philadelphia, PA 19104, United States of America
| | - Wenzheng Sun
- Institute of Information Science and Engineering, Shandong University, Shandong, People’s Republic of China
| | - Zi Yang
- Department of Radiation Oncology, UT Southwestern Medical Center, 5151 Harry Hines Boulevard Dallas, TX 75390, United States of America
| | - Fang-Fang Yin
- Medical Physics Graduate Program, Duke University, 2424 Erwin Road Suite 101, Durham, NC 27705, United States of America
- Department of Radiation Oncology, Duke University Medical Center, DUMC Box 3295, Durham, NC 27710, United States of America
| | - Lei Ren
- Medical Physics Graduate Program, Duke University, 2424 Erwin Road Suite 101, Durham, NC 27705, United States of America
- Department of Radiation Oncology, Duke University Medical Center, DUMC Box 3295, Durham, NC 27710, United States of America
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Caillet V, O'Brien R, Moore D, Poulsen P, Pommer T, Colvill E, Sawant A, Booth J, Keall P. Technical Note: In silico and experimental evaluation of two leaf-fitting algorithms for MLC tracking based on exposure error and plan complexity. Med Phys 2019; 46:1814-1820. [PMID: 30719723 DOI: 10.1002/mp.13425] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 01/13/2019] [Accepted: 01/14/2019] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Multileaf collimator (MLC) tracking is being clinically pioneered to continuously compensate for thoracic and pelvic motion during radiotherapy. The purpose of this work was to characterize the performance of two MLC leaf-fitting algorithms, direct optimization and piecewise optimization, for real-time motion compensation with different plan complexity and tumor trajectories. METHODS To test the algorithms, both in silico and phantom experiments were performed. The phantom experiments were performed on a Trilogy Varian linac and a HexaMotion programmable motion platform. High and low modulation VMAT plans for lung and prostate cancer cases were used along with eight patient-measured organ-specific trajectories. For both MLC leaf-fitting algorithms, the plans were run with their corresponding patient trajectories. To compare algorithms, the average exposure errors, i.e., the difference in shape between ideal and fitted MLC leaves by the algorithm, plan complexity and system latency of each experiment were calculated. RESULTS Comparison of exposure errors for the in silico and phantom experiments showed minor differences between the two algorithms. The average exposure errors for in silico experiments with low/high plan complexity were 0.66/0.88 cm2 for direct optimization and 0.66/0.88 cm2 for piecewise optimization, respectively. The average exposure errors for the phantom experiments with low/high plan complexity were 0.73/1.02 cm2 for direct and 0.73/1.02 cm2 for piecewise optimization, respectively. The measured latency for the direct optimization was 226 ± 10 ms and for the piecewise algorithm was 228 ± 10 ms. In silico and phantom exposure errors quantified for each treatment plan demonstrated that the exposure errors from the high plan complexity (0.96 cm2 mean, 2.88 cm2 95% percentile) were all significantly different from the low plan complexity (0.70 cm2 mean, 2.18 cm2 95% percentile) (P < 0.001, two-tailed, Mann-Whitney statistical test). CONCLUSIONS The comparison between the two leaf-fitting algorithms demonstrated no significant differences in exposure errors, neither in silico nor with phantom experiments. This study revealed that plan complexity impacts the overall exposure errors significantly more than the difference between the algorithms.
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Affiliation(s)
- Vincent Caillet
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Ricky O'Brien
- ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Douglas Moore
- Beyond Center for Fundamental Concepts in Science, Arizona State University, Tempe, AZ, USA
| | | | - Tobias Pommer
- Unit of Radiotherapy Physics and Engineering, Karolinska University Hospital, Solna, Sweden
| | - Emma Colvill
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Amit Sawant
- Department of Radiation Oncology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Jeremy Booth
- Northern Sydney Cancer Centre, Sydney, NSW, Australia.,ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
| | - Paul Keall
- ACRF Image X Institute, Sydney Medical School, University of Sydney, Sydney, NSW, Australia
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8
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Grimwood A, McNair HA, O'Shea TP, Gilroy S, Thomas K, Bamber JC, Tree AC, Harris EJ. In Vivo Validation of Elekta's Clarity Autoscan for Ultrasound-based Intrafraction Motion Estimation of the Prostate During Radiation Therapy. Int J Radiat Oncol Biol Phys 2018; 102:912-921. [PMID: 29859785 PMCID: PMC6202949 DOI: 10.1016/j.ijrobp.2018.04.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Revised: 05/11/2018] [Accepted: 05/11/2018] [Indexed: 02/08/2023]
Abstract
PURPOSE Our purpose was to perform an in vivo validation of ultrasound imaging for intrafraction motion estimation using the Elekta Clarity Autoscan system during prostate radiation therapy. The study was conducted as part of the Clarity-Pro trial (NCT02388308). METHODS AND MATERIALS Initial locations of intraprostatic fiducial markers were identified from cone beam computed tomography scans. Marker positions were translated according to Clarity intrafraction 3-dimensional prostate motion estimates. The updated locations were projected onto the 2-dimensional electronic portal imager plane. These Clarity-based estimates were compared with the actual portal-imaged 2-dimensional marker positions. Images from 16 patients encompassing 80 fractions were analyzed. To investigate the influence of intraprostatic markers and image quality on ultrasound motion estimation, 3 observers rated image quality, and the marker visibility on ultrasound images was assessed. RESULTS The median difference between Clarity-defined intrafraction marker locations and portal-imaged marker locations was 0.6 mm (with 95% limit of agreement at 2.5 mm). Markers were identified on ultrasound in only 3 of a possible 240 instances. No linear relationship between image quality and Clarity motion estimation confidence was identified. The difference between Clarity-based motion estimates and electronic portal-imaged marker location was also independent of image quality. Clarity estimation confidence was degraded in a single fraction owing to poor probe placement. CONCLUSIONS The accuracy of Clarity intrafraction prostate motion estimation is comparable with that of other motion-monitoring systems in radiation therapy. The effect of fiducial markers in the study was deemed negligible as they were rarely visible on ultrasound images compared with intrinsic anatomic features. Clarity motion estimation confidence was robust to variations in image quality and the number of ultrasound-imaged anatomic features; however, it was degraded as a result of poor probe placement.
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Affiliation(s)
- Alexander Grimwood
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK.
| | - Helen A McNair
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
| | - Tuathan P O'Shea
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
| | - Stephen Gilroy
- North West Cancer Centre, Altnagelvin Area Hospital, Londonderry, Ireland
| | - Karen Thomas
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
| | - Jeffrey C Bamber
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
| | - Alison C Tree
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
| | - Emma J Harris
- Division of Radiotherapy and Imaging, The Institute of Cancer Research and Royal Marsden Hospital Trust, Sutton, UK
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Ravkilde T, Skouboe S, Hansen R, Worm E, Poulsen PR. First online real-time evaluation of motion-induced 4D dose errors during radiotherapy delivery. Med Phys 2018; 45:3893-3903. [PMID: 29869789 DOI: 10.1002/mp.13037] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 05/24/2018] [Accepted: 05/25/2018] [Indexed: 12/25/2022] Open
Abstract
PURPOSE In radiotherapy, dose deficits caused by tumor motion often far outweigh the discrepancies typically allowed in plan-specific quality assurance (QA). Yet, tumor motion is not usually included in present QA. We here present a novel method for online treatment verification by real-time motion-including four-dimensional (4D) dose reconstruction and dose evaluation and demonstrate its use during stereotactic body radiotherapy (SBRT) delivery with and without MLC tracking. METHODS Five volumetric-modulated arc therapy (VMAT) plans were delivered with and without MLC tracking to a motion stage carrying a Delta4 dosimeter. The VMAT plans have previously been used for (nontracking) liver SBRT with intratreatment tumor motion recorded by kilovoltage intrafraction monitoring (KIM). The motion stage reproduced the KIM-measured tumor motions in three dimensions (3D) while optical monitoring guided the MLC tracking. Linac parameters and the target position were streamed to an in-house developed software program (DoseTracker) that performed real-time 4D dose reconstructions and 3%/3 mm γ-evaluations of the reconstructed cumulative dose using a concurrently reconstructed planned dose without target motion as reference. Offline, the real-time reconstructed doses and γ-evaluations were validated against 4D dosimeter measurements performed during the experiments. RESULTS In total, 181,120 dose reconstructions and 5,237 γ-evaluations were performed online and in real time with median computation times of 30 ms and 1.2 s, respectively. The mean (standard deviation) difference between reconstructed and measured doses was -1.2% (4.9%) for transient doses and -1.5% (3.9%) for cumulative doses. The root-mean-square deviation between reconstructed and measured motion-induced γ-fail rates was 2.0%-point. The mean (standard deviation) sensitivity and specificity of DoseTracker to predict γ-fail rates above a given threshold was 96.8% (3.5%) and 99.2% (0.4%), respectively, for clinically relevant thresholds between 1% and 30% γ-fail rate. CONCLUSIONS Real-time delivery-specific QA during radiotherapy of moving targets was demonstrated for the first time. It allows supervision of treatment accuracy and action on treatment discrepancy within 2 s with high sensitivity and specificity.
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Affiliation(s)
- Thomas Ravkilde
- Medical Physics, Department of Oncology, Aarhus University Hospital, 8000, Aarhus C, Denmark
| | - Simon Skouboe
- Department of Oncology, Aarhus University Hospital, 8000, Aarhus C, Denmark
| | - Rune Hansen
- Medical Physics, Department of Oncology, Aarhus University Hospital, 8000, Aarhus C, Denmark
| | - Esben Worm
- Medical Physics, Department of Oncology, Aarhus University Hospital, 8000, Aarhus C, Denmark
| | - Per R Poulsen
- Department of Oncology, Aarhus University Hospital, 8000, Aarhus C, Denmark
- Institute for Clinical Medicine, Aarhus University, 8200, Aarhus N, Denmark
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Toftegaard J, Keall PJ, O'Brien R, Ruan D, Ernst F, Homma N, Ichiji K, Poulsen PR. Potential improvements of lung and prostate MLC tracking investigated by treatment simulations. Med Phys 2018; 45:2218-2229. [DOI: 10.1002/mp.12868] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 03/07/2018] [Accepted: 03/07/2018] [Indexed: 12/25/2022] Open
Affiliation(s)
- Jakob Toftegaard
- Department of Oncology; Aarhus University Hospital; 8000 Aarhus C Denmark
| | - Paul J. Keall
- Radiation Physics Laboratory; Sydney Medical School; University of Sydney; Sydney New South Wales 2006 Australia
| | - Ricky O'Brien
- Radiation Physics Laboratory; Sydney Medical School; University of Sydney; Sydney New South Wales 2006 Australia
| | - Dan Ruan
- Department of Radiation Oncology; University of California; Los Angeles CA 90095 USA
| | - Floris Ernst
- Institute for Robotics and Cognitive Systems; University of Lübeck; Lübeck 23562 Germany
| | - Noriyasu Homma
- Department of Radiological Imaging and Informatics; Tohoku University Graduate School of Medicine; Sendai 980-8579 Japan
| | - Kei Ichiji
- Department of Radiological Imaging and Informatics; Tohoku University Graduate School of Medicine; Sendai 980-8579 Japan
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Reduction of intra-fraction prostate motion - Determining optimal bladder volume and filling for prostate radiotherapy using daily 4D TPUS and CBCT. Tech Innov Patient Support Radiat Oncol 2018; 5:9-15. [PMID: 32095569 PMCID: PMC7033810 DOI: 10.1016/j.tipsro.2018.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/22/2018] [Accepted: 01/22/2018] [Indexed: 11/22/2022] Open
Abstract
An optimal bladder volume and filling protocol is proposed. The current hydration protocol was well-accepted and tolerated.
Background and purpose Inconsistent bladder and rectal volumes have been associated with motion uncertainties during prostate radiotherapy. This study investigates the impact of these volumes to determine the optimal bladder volume. Materials and methods 60 patients from two Asian hospitals were recruited prospectively. 1887 daily cone-beam computed tomography (CBCT) images were analysed. Intra-fraction motion of the prostate was monitored real-time using a four-dimension transperineal ultrasound (4D TPUS) Clarity® system. The impact of planned bladder volume, adequacy of daily bladder filling, and rectum volume on mean intra-fraction motion of the prostate was analysed. Patients’ ability to comply with the full bladder hydration protocol and level of frustration was assessed using a questionaire. Acute side effects were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 and quality of life (QoL) assessed using the International Prostate Symptom Score (IPSS). Results The mean (SD) bladder and rectum volumes achieved during daily treatment were 139.7 cm3 (82.4 cm3) and 53.3 cm3 (18 cm3) respectively. Mean (SD) percentage change from planned CT volumes in bladder volume was reduced by 8.2% (48.7%) and rectum volume was increased by 12.4% (42.2%). Linear Mixed effect model analysis revealed a reduction in intra-fraction motion in both the Sup/Inf (p = 0.008) and Ant/Post (p = 0.0001) directions when the daily bladder was filled between 82 and 113% (3rd Quartiles) of the planned CT volumes. A reduction in intra-fraction motion of the prostate in the Ant/Post direction (z-plane) (p = 0.03) was observed when the planned bladder volume was greater than 200 ml. Patients complied well with the hydration protocol with minimal frustration (mean (SD) scores of 2.1 (1.4) and 1.8 (1.2) respectively). There was a moderate positive correlation (0.496) between mean bladder volume and IPSS reported post-treatment urinary straining (p = 0.001). Conclusions A planned bladder volume >200 cm3 and daily filling between 82 and 113%, reduced intra-fraction motion of the prostate. The hydration protocol was well tolerated.
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Pasler M, Hernandez V, Jornet N, Clark CH. Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques. Phys Imaging Radiat Oncol 2018; 5:76-84. [PMID: 33458373 PMCID: PMC7807589 DOI: 10.1016/j.phro.2018.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 03/08/2018] [Accepted: 03/08/2018] [Indexed: 11/25/2022] Open
Abstract
With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.
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Affiliation(s)
- Marlies Pasler
- Lake Constance Radiation Oncology Center Singen-Friedrichshafen, Germany
| | - Victor Hernandez
- Department of Medical Physics, Hospital Sant Joan de Reus, IISPV, Tarragona, Spain
| | - Núria Jornet
- Servei de RadiofísicaiRadioprotecció, Hospital de la Santa CreuiSant Pau, Spain
| | - Catharine H. Clark
- Department of Medical Physics, Royal Surrey County Hospital, Guildford, Surrey, UK
- Metrology for Medical Physics (MEMPHYS), National Physical Laboratory, Teddington, Middlesex, UK
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Richter D, Lehmann HI, Eichhorn A, Constantinescu AM, Kaderka R, Prall M, Lugenbiel P, Takami M, Thomas D, Bert C, Durante M, Packer DL, Graeff C. ECG-based 4D-dose reconstruction of cardiac arrhythmia ablation with carbon ion beams: application in a porcine model. ACTA ACUST UNITED AC 2017. [DOI: 10.1088/1361-6560/aa7b67] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Toftegaard J, Hansen R, Ravkilde T, Macek K, Poulsen PR. An experimentally validated couch and MLC tracking simulator used to investigate hybrid couch-MLC tracking. Med Phys 2017; 44:798-809. [PMID: 28079260 DOI: 10.1002/mp.12104] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/03/2017] [Accepted: 01/05/2017] [Indexed: 12/25/2022] Open
Abstract
PURPOSE/OBJECTIVE Couch and MLC tracking are two novel techniques to mitigate intrafractional tumor motion on a conventional linear accelerator, but both techniques still have residual dosimetric errors. Here, we first propose and experimentally validate a software tool to simulate couch and MLC tracking, and then use the simulator to study hybrid couch-MLC tracking for improved tracking performance. MATERIALS AND METHODS The tracking simulator requires a treatment plan and a motion trajectory as input and simulates the delivered monitor units and motion of all accelerator parts as function of time. The simulator outputs accelerator log files synchronized with the target motion as well as the MLC exposure error, which is a simple dose error surrogate. A series of couch and MLC tracking experiments were used to determine appropriate parameters for the simulator dynamics and to validate the simulator by its ability to reproduce the experimental tracking accuracy. Three hybrid couch-MLC tracking strategies were investigated. All strategies divided the target motion in beam's eye view into motion perpendicular and parallel to the MLC leaves. In the hybrid strategies, couch tracking compensated for the following target motion components (in order of decreasing couch tracking contribution): (a) all perpendicular motion, (b) residual perpendicular motion less than half a leaf width, and (c) persistent residual perpendicular motion that was stable at a time scale of 1s. MLC tracking compensated for the remaining target motion. All tracking strategies were simulated with two prostate and two lung cancer single-arc VMAT plans using 695 prostate trajectories and 160 lung tumor trajectories. The tracking error was quantified as the MLC exposure error. The couch motion was quantified as the mean speed, acceleration, and jerk of the couch. RESULTS The simulator reproduced the experimental gantry position with a mean (maximum) root-mean-square (rms) error of 0.07°(0.2°). The geometrical rms tracking error was reproduced with mean (maximum) absolute errors of 0.20 mm(0.23 mm) and 0.1 mm(0.23 mm) for MLC tracking parallel and perpendicular to the MLC leaves, and 0.40 mm(0.46 mm), 0.09 mm(0.25 mm), and 0.20 mm(0.46 mm) for couch tracking in the left-right, anterior-posterior, and cranio-caudal directions. The MLC exposure error of VMAT MLC tracking was reproduced with a mean absolute error of 5.6%. All hybrid tracking strategies reduced the couch motion relative to pure couch tracking and improved the tracking accuracy compared with pure MLC tracking. The mean MLC exposure error reduction relative to no tracking was 66.6% (couch tracking), 72.9% (hybrid (1)), 70.2% (2), 59.1% (3), and 55.6% (MLC tracking) for lung tumor motion and 76.5% (couch tracking), 76.1% (1), 74.3% (2), 72.3% (3), and 35.9% (MLC tracking) for prostate motion. For prostate motion, pure MLC tracking resulted in rather large MLC exposure errors that were more than halved with all hybrid tracking strategies. CONCLUSION A couch and MLC tracking simulator was developed and experimentally validated against a series of tracking experiments. All hybrid couch-MLC tracking strategies improved MLC tracking. Two strategies also improved couch tracking of lung tumors. In particular, MLC tracking of prostate may be greatly improved by a modest degree of couch motion.
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Affiliation(s)
- Jakob Toftegaard
- Department of Oncology, Aarhus University Hospital, Aarhus C, 8000, Denmark
| | - Rune Hansen
- Department of Medical Physics, Aarhus University Hospital, Aarhus C, 8000, Denmark
| | - Thomas Ravkilde
- Department of Medical Physics, Aarhus University Hospital, Aarhus C, 8000, Denmark
| | - Kristijan Macek
- Varian Medical Systems, Imaging Laboratory GmbH, Baden-Daettwil, 5405, Switzerland
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Ipsen S, Bruder R, O'Brien R, Keall PJ, Schweikard A, Poulsen PR. Online 4D ultrasound guidance for real-time motion compensation by MLC tracking. Med Phys 2017; 43:5695. [PMID: 27782689 DOI: 10.1118/1.4962932] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE With the trend in radiotherapy moving toward dose escalation and hypofractionation, the need for highly accurate targeting increases. While MLC tracking is already being successfully used for motion compensation of moving targets in the prostate, current real-time target localization methods rely on repeated x-ray imaging and implanted fiducial markers or electromagnetic transponders rather than direct target visualization. In contrast, ultrasound imaging can yield volumetric data in real-time (3D + time = 4D) without ionizing radiation. The authors report the first results of combining these promising techniques-online 4D ultrasound guidance and MLC tracking-in a phantom. METHODS A software framework for real-time target localization was installed directly on a 4D ultrasound station and used to detect a 2 mm spherical lead marker inside a water tank. The lead marker was rigidly attached to a motion stage programmed to reproduce nine characteristic tumor trajectories chosen from large databases (five prostate, four lung). The 3D marker position detected by ultrasound was transferred to a computer program for MLC tracking at a rate of 21.3 Hz and used for real-time MLC aperture adaption on a conventional linear accelerator. The tracking system latency was measured using sinusoidal trajectories and compensated for by applying a kernel density prediction algorithm for the lung traces. To measure geometric accuracy, static anterior and lateral conformal fields as well as a 358° arc with a 10 cm circular aperture were delivered for each trajectory. The two-dimensional (2D) geometric tracking error was measured as the difference between marker position and MLC aperture center in continuously acquired portal images. For dosimetric evaluation, VMAT treatment plans with high and low modulation were delivered to a biplanar diode array dosimeter using the same trajectories. Dose measurements with and without MLC tracking were compared to a static reference dose using 3%/3 mm and 2%/2 mm γ-tests. RESULTS The overall tracking system latency was 172 ms. The mean 2D root-mean-square tracking error was 1.03 mm (0.80 mm prostate, 1.31 mm lung). MLC tracking improved the dose delivery in all cases with an overall reduction in the γ-failure rate of 91.2% (3%/3 mm) and 89.9% (2%/2 mm) compared to no motion compensation. Low modulation VMAT plans had no (3%/3 mm) or minimal (2%/2 mm) residual γ-failures while tracking reduced the γ-failure rate from 17.4% to 2.8% (3%/3 mm) and from 33.9% to 6.5% (2%/2 mm) for plans with high modulation. CONCLUSIONS Real-time 4D ultrasound tracking was successfully integrated with online MLC tracking for the first time. The developed framework showed an accuracy and latency comparable with other MLC tracking methods while holding the potential to measure and adapt to target motion, including rotation and deformation, noninvasively.
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Affiliation(s)
- Svenja Ipsen
- Institute for Robotics and Cognitive Systems, University of Luebeck, Luebeck 23562, Germany
| | - Ralf Bruder
- Institute for Robotics and Cognitive Systems, University of Luebeck, Luebeck 23562, Germany
| | - Rick O'Brien
- Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006, Australia
| | - Paul J Keall
- Radiation Physics Laboratory, Sydney Medical School, University of Sydney, NSW 2006, Australia
| | - Achim Schweikard
- Institute for Robotics and Cognitive Systems, University of Luebeck, Luebeck 23562, Germany
| | - Per R Poulsen
- Department of Clinical Medicine, Aarhus University and Department of Oncology, Aarhus University Hospital, Aarhus 8000, Denmark
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Murtaza G, Toftegaard J, Khan EU, Poulsen PR. Volumetric modulated arc therapy with dynamic collimator rotation for improved multileaf collimator tracking of the prostate. Radiother Oncol 2017; 122:109-115. [DOI: 10.1016/j.radonc.2016.11.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/31/2016] [Accepted: 11/03/2016] [Indexed: 12/01/2022]
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Persoon L, Podesta M, Nijsten S, Troost E, Verhaegen F. Time-Resolved Versus Integrated Transit Planar Dosimetry for Volumetric Modulated Arc Therapy. Technol Cancer Res Treat 2016; 15:NP79-NP87. [PMID: 26655145 DOI: 10.1177/1533034615617668] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 09/16/2015] [Accepted: 10/23/2015] [Indexed: 11/16/2022] Open
Abstract
Purpose: It is desirable that dosimetric deviations during radiation treatments are detected. Integrated transit planar dosimetry is commonly used to evaluate external beam treatments such as volumetric-modulated arc therapy. This work focuses on patient geometry changes which result in differences between the planned and the delivered radiation dose. Integrated transit planar dosimetry will average out some deviations. Novel time-resolved transit planar dosimetry compares the delivered dose of volumetric-modulated arc therapy to the planned dose at various time points. Four patient cases are shown where time-resolved transit planar dosimetry detects patient geometry changes during treatment. Methods: A control point to control point comparison between the planned dose and the treatment dose of volumetric-modulated arc therapy beams is calculated using the planning computed tomography and the kV cone-beam computed tomography of the day and evaluated with a time-resolved γ function. Results were computed for 4 patients treated with volumetric-modulated arc therapy, each showing an anatomical change: pleural effusion, rectal gas pockets, and tumor regression. Results: In all cases, the geometrical change was detected by time-resolved transit planar dosimetry, whereas integrated transit planar dosimetry showed minor or no indication of the dose discrepancy. Both tumor regression cases were detected earlier in the treatment with time-resolved planar dosimetry in comparison to integrated transit planar dosimetry. The pleural effusion and the gas pocket were detected exclusively with time-resolved transit planar dosimetry. Conclusions: Clinical cases were presented in this proof-of-principle study in which integrated transit planar dosimetry did not detect dosimetrically relevant deviations to the same extent time-resolved transit planar dosimetry was able to. Time-resolved transit planar dosimetry also provides results that can be presented as a function of arc delivery angle allowing easier interpretation compared to integrated transit planar dosimetry.
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Affiliation(s)
- L.C.G.G. Persoon
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - M. Podesta
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - S.M.J.J.G. Nijsten
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - E.G.C. Troost
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - F. Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
- Medical Physics Unit, Department of Oncology, McGill University, Montréal, Québec, Canada
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Hansen R, Ravkilde T, Worm ES, Toftegaard J, Grau C, Macek K, Poulsen PR. Electromagnetic guided couch and multileaf collimator tracking on a TrueBeam accelerator. Med Phys 2016; 43:2387. [DOI: 10.1118/1.4946815] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Fast MF, Kamerling CP, Ziegenhein P, Menten MJ, Bedford JL, Nill S, Oelfke U. Assessment of MLC tracking performance during hypofractionated prostate radiotherapy using real-time dose reconstruction. Phys Med Biol 2016; 61:1546-62. [PMID: 26816273 PMCID: PMC5390952 DOI: 10.1088/0031-9155/61/4/1546] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/25/2015] [Accepted: 12/16/2015] [Indexed: 11/16/2022]
Abstract
By adapting to the actual patient anatomy during treatment, tracked multi-leaf collimator (MLC) treatment deliveries offer an opportunity for margin reduction and healthy tissue sparing. This is assumed to be especially relevant for hypofractionated protocols in which intrafractional motion does not easily average out. In order to confidently deliver tracked treatments with potentially reduced margins, it is necessary to monitor not only the patient anatomy but also the actually delivered dose during irradiation. In this study, we present a novel real-time online dose reconstruction tool which calculates actually delivered dose based on pre-calculated dose influence data in less than 10 ms at a rate of 25 Hz. Using this tool we investigate the impact of clinical target volume (CTV) to planning target volume (PTV) margins on CTV coverage and organ-at-risk dose. On our research linear accelerator, a set of four different CTV-to-PTV margins were tested for three patient cases subject to four different motion conditions. Based on this data, we can conclude that tracking eliminates dose cold spots which can occur in the CTV during conventional deliveries even for the smallest CTV-to-PTV margin of 1 mm. Changes of organ-at-risk dose do occur frequently during MLC tracking and are not negligible in some cases. Intrafractional dose reconstruction is expected to become an important element in any attempt of re-planning the treatment plan during the delivery based on the observed anatomy of the day.
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Affiliation(s)
- M F Fast
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - C P Kamerling
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - P Ziegenhein
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - M J Menten
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - J L Bedford
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - S Nill
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
| | - U Oelfke
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London SM2 5NG, UK
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Fleckenstein J, Hesser J, Wenz F, Lohr F. Robustness of sweeping-window arc therapy treatment sequences against intrafractional tumor motion. Med Phys 2015; 42:1538-45. [PMID: 25832044 DOI: 10.1118/1.4914166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Due to the potentially periodic collimator dynamic in volumetric modulated arc therapy (VMAT) dose deliveries with the sweeping-window arc therapy (SWAT) technique, additional manifestations of dosimetric deviations in the presence of intrafractional motion may occur. With a fast multileaf collimator (MLC), and a flattening filter free dose delivery, treatment times close to 60 s per fraction are clinical reality. For these treatment sequences, the human breathing period can be close to the collimator sweeping period. Compared to a random arrangement of the segments, this will cause a further degradation of the dose homogeneity. METHODS Fifty VMAT sequences of potentially moving target volumes were delivered on a two dimensional ionization chamber array. In order to detect interplay effects along all three coordinate axes, time resolved measurements were performed twice--with the detector aligned in vertical (V) or horizontal (H) orientation. All dose matrices were then moved within a simulation software by a time-dependent motion vector. The minimum relative equivalent uniform dose EUDr,m for all breathing starting phases was determined for each amplitude and period. Furthermore, an estimation of periods with minimum EUD was performed. Additionally, LINAC logfiles were recorded during plan delivery. The MLC, jaw, gantry angle, and monitor unit settings were continuously saved and used to calculate the correlation coefficient between the target motion and the dose weighed collimator motion component for each direction (CC, LR, AP) separately. RESULTS The resulting EUDr,m were EUDr,m(CCV) = (98.3 ± 0.6)%, EUDr,m(CCH) = (98.6 ± 0.5)%, EUDr,m(APV) = (97.7 ± 0.9)%, and EUDr,m(LRH) = (97.8 ± 0.9)%. The overall minimum relative EUD observed for 360(∘) arc midventilation treatments was 94.6%. The treatment plan with the shortest period and a minimum relative EUD of less than 97% was found at T = 6.1 s. For a partial 120(∘) arc, an EUDr,m = 92.0% was found. In all cases, a correlation coefficient above 0.5 corresponded to a minimum in EUD. CONCLUSIONS With the advent of fast VMAT delivery techniques, nonrobust treatment sequences for human breathing patterns can be generated. These sequences are characterized by a large correlation coefficient between a target motion component and the corresponding collimator dynamic. By iteratively decreasing the maximum allowed dose rate, a low correlation coefficient and consequentially a robust treatment sequence are ensured.
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Affiliation(s)
- Jens Fleckenstein
- Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim 68167, Germany
| | - Jürgen Hesser
- Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim 68167, Germany
| | - Frederik Wenz
- Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim 68167, Germany
| | - Frank Lohr
- Department of Radiation Oncology, University Medical Center Mannheim, Heidelberg University, Theodor-Kutzer-Ufer 1-3, Mannheim 68167, Germany
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Feygelman V, Tonner B, Stambaugh C, Hunt D, Zhang G, Moros E, Nelms BE. Technical Note: Motion‐perturbation method applied to dosimetry of dynamic MLC target tracking—A proof‐of‐concept. Med Phys 2015; 42:6147-51. [DOI: 10.1118/1.4931605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Vladimir Feygelman
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612
| | - Brian Tonner
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612
| | | | - Dylan Hunt
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612
| | - Geoffrey Zhang
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612
| | - Eduardo Moros
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida 33612
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Ravkilde T, Keall PJ, Grau C, Høyer M, Poulsen PR. Fast motion-including dose error reconstruction for VMAT with and without MLC tracking. Phys Med Biol 2014; 59:7279-96. [DOI: 10.1088/0031-9155/59/23/7279] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Ge Y, O'Brien RT, Shieh CC, Booth JT, Keall PJ. Toward the development of intrafraction tumor deformation tracking using a dynamic multi-leaf collimator. Med Phys 2014; 41:061703. [PMID: 24877798 PMCID: PMC4032435 DOI: 10.1118/1.4873682] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 03/31/2014] [Accepted: 04/14/2014] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Intrafraction deformation limits targeting accuracy in radiotherapy. Studies show tumor deformation of over 10 mm for both single tumor deformation and system deformation (due to differential motion between primary tumors and involved lymph nodes). Such deformation cannot be adapted to with current radiotherapy methods. The objective of this study was to develop and experimentally investigate the ability of a dynamic multi-leaf collimator (DMLC) tracking system to account for tumor deformation. METHODS To compensate for tumor deformation, the DMLC tracking strategy is to warp the planned beam aperture directly to conform to the new tumor shape based on real time tumor deformation input. Two deformable phantoms that correspond to a single tumor and a tumor system were developed. The planar deformations derived from the phantom images in beam's eye view were used to guide the aperture warping. An in-house deformable image registration software was developed to automatically trigger the registration once new target image was acquired and send the computed deformation to the DMLC tracking software. Because the registration speed is not fast enough to implement the experiment in real-time manner, the phantom deformation only proceeded to the next position until registration of the current deformation position was completed. The deformation tracking accuracy was evaluated by a geometric target coverage metric defined as the sum of the area incorrectly outside and inside the ideal aperture. The individual contributions from the deformable registration algorithm and the finite leaf width to the tracking uncertainty were analyzed. Clinical proof-of-principle experiment of deformation tracking using previously acquired MR images of a lung cancer patient was implemented to represent the MRI-Linac environment. Intensity-modulated radiation therapy (IMRT) treatment delivered with enabled deformation tracking was simulated and demonstrated. RESULTS The first experimental investigation of adapting to tumor deformation has been performed using simple deformable phantoms. For the single tumor deformation, the A(u)+A(o) was reduced over 56% when deformation was larger than 2 mm. Overall, the total improvement was 82%. For the tumor system deformation, the A(u)+A(o) reductions were all above 75% and the total A(u)+A(o) improvement was 86%. Similar coverage improvement was also found in simulating deformation tracking during IMRT delivery. The deformable image registration algorithm was identified as the dominant contributor to the tracking error rather than the finite leaf width. The discrepancy between the warped beam shape and the ideal beam shape due to the deformable registration was observed to be partially compensated during leaf fitting due to the finite leaf width. The clinical proof-of-principle experiment demonstrated the feasibility of intrafraction deformable tracking for clinical scenarios. CONCLUSIONS For the first time, we developed and demonstrated an experimental system that is capable of adapting the MLC aperture to account for tumor deformation. This work provides a potentially widely available management method to effectively account for intrafractional tumor deformation. This proof-of-principle study is the first experimental step toward the development of an image-guided radiotherapy system to treat deforming tumors in real-time.
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Affiliation(s)
- Yuanyuan Ge
- Radiation Physics Laboratory, University of Sydney, NSW 2006, Australia
| | - Ricky T O'Brien
- Radiation Physics Laboratory, University of Sydney, NSW 2006, Australia
| | - Chun-Chien Shieh
- Radiation Physics Laboratory, University of Sydney, NSW 2006, Australia
| | - Jeremy T Booth
- Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW 2065, Australia
| | - Paul J Keall
- Radiation Physics Laboratory, University of Sydney, NSW 2006, Australia
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