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Putz F, Bock M, Schmitt D, Bert C, Blanck O, Ruge MI, Hattingen E, Karger CP, Fietkau R, Grigo J, Schmidt MA, Bäuerle T, Wittig A. Quality requirements for MRI simulation in cranial stereotactic radiotherapy: a guideline from the German Taskforce "Imaging in Stereotactic Radiotherapy". Strahlenther Onkol 2024; 200:1-18. [PMID: 38163834 PMCID: PMC10784363 DOI: 10.1007/s00066-023-02183-6] [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: 09/01/2023] [Accepted: 11/06/2023] [Indexed: 01/03/2024]
Abstract
Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.
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Affiliation(s)
- Florian Putz
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
| | - Michael Bock
- Klinik für Radiologie-Medizinphysik, Universitätsklinikum Freiburg, Freiburg, Germany
| | - Daniela Schmitt
- Klinik für Strahlentherapie und Radioonkologie, Universitätsmedizin Göttingen, Göttingen, Germany
| | - Christoph Bert
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Oliver Blanck
- Klinik für Strahlentherapie, Universitätsklinikum Schleswig-Holstein, Campus Kiel, Kiel, Germany
| | - Maximilian I Ruge
- Klinik für Stereotaxie und funktionelle Neurochirurgie, Zentrum für Neurochirurgie, Universitätsklinikum Köln, Cologne, Germany
| | - Elke Hattingen
- Institut für Neuroradiologie, Universitätsklinikum Frankfurt, Frankfurt am Main, Germany
| | - Christian P Karger
- Abteilung Medizinische Physik in der Strahlentherapie, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany
- Nationales Zentrum für Strahlenforschung in der Onkologie (NCRO), Heidelberger Institut für Radioonkologie (HIRO), Heidelberg, Germany
| | - Rainer Fietkau
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Johanna Grigo
- Strahlenklinik, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Manuel A Schmidt
- Neuroradiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tobias Bäuerle
- Radiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Andrea Wittig
- Klinik und Poliklinik für Strahlentherapie und Radioonkologie, Universitätsklinikum Würzburg, Würzburg, Germany
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Masitho S, Szkitsak J, Grigo J, Fietkau R, Putz F, Bert C. Feasibility of artificial-intelligence-based synthetic computed tomography in a magnetic resonance-only radiotherapy workflow for brain radiotherapy: two-way dose validation and 2D/2D kV-image-based positioning. Phys Imaging Radiat Oncol 2022; 24:111-117. [DOI: 10.1016/j.phro.2022.10.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/12/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022] Open
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Law MWL, Yuan J, Wong OL, Ying AD, Zhou Y, Cheung KY, Yu SK. Phantom assessment of three-dimensional geometric distortion of a dedicated wide-bore MR-simulator for radiotherapy. Biomed Phys Eng Express 2021; 8. [PMID: 34874313 DOI: 10.1088/2057-1976/ac3f4f] [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: 07/20/2021] [Accepted: 12/02/2021] [Indexed: 11/11/2022]
Abstract
This study evaluated the machine-dependent three-dimensional geometric distortion images acquired from a 1.5T 700mm-wide bore MR-simulator based on a large geometric accuracy phantom. With the consideration of radiation therapy (RT) application requirements, every sequence was examined in various combinations of acquisition-orientations and receiver-bandwidths with console-integrated distortion correction enabled. Distortion was repeatedly measured over a six-month period. The distortion measured from the images acquired at the beginning of this period was employed to retrospectively correct the distortion in the subsequent acquisitions. Geometric distortion was analyzed within the largest field-of-view allowed. Six sequences were examined for comprehensive distortion analysis - VIBE, SPACE, TSE, FLASH, BLADE and PETRA. Based on optimal acquisition parameters, their diameter-sphere-volumes (DSVs) of CT-comparable geometric fidelity (where 1mm distortion was allowed) were 333.6mm, 315.1mm, 316.0mm, 318.9mm, 306.2mm and 314.5mm respectively. This was a significant increase from 254.0mm, 245.5mm, 228.9mm, 256.6mm, 230.8mm and 254.2mm DSVs respectively, when images were acquired using un-optimized parameters. The longitudinal stability of geometric distortion and the efficacy of retrospective correction of console-corrected images, based on prior distortion measurements, were inspected using VIBE and SPACE. The retrospectively corrected images achieved over 500mm DSVs with 1mm distortion allowed. The median distortion was below 1mm after retrospective correction, proving that obtaining prior distortion map for subsequent retrospective distortion correction is beneficial. The systematic evaluation of distortion using various combinations of sequence-type, acquisition-orientation and receiver-bandwidth in a six-month time span would be a valuable guideline for optimizing sequence for various RT applications.
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Affiliation(s)
- Max W L Law
- Medical Physics Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, 000, HONG KONG
| | - Jing Yuan
- Research Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, 000, HONG KONG
| | - Oi Lei Wong
- Research Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, NA, 000, HONG KONG
| | - Abby D Ying
- Medical Physics Department, Hong Kong Sanatorium and Hospital, Hong Kong Sanatorium and Hospital, Hong Kong, HONG KONG
| | - Yihang Zhou
- Research Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, 000, HONG KONG
| | - Kin Yin Cheung
- Medical Physics Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, 000, HONG KONG
| | - Siu Ki Yu
- Medical Physics Department, Hong Kong Sanatorium and Hospital, 2nd Village Road, Happy Valley, Hong Kong Island, Hong Kong, 000, HONG KONG
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Zhou Y, Yuan J, Wong OL, Fung WWK, Cheng KF, Cheung KY, Yu SK. Assessment of positional reproducibility in the head and neck on a 1.5-T MR simulator for an offline MR-guided radiotherapy solution. Quant Imaging Med Surg 2018; 8:925-935. [PMID: 30505721 DOI: 10.21037/qims.2018.10.03] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Recently, a shuttle-based offline magnetic resonance-guided radiotherapy (MRgRT) approach was proposed. This study aims to evaluate the positional reproducibility in the immobilized head and neck using a 1.5-T MR-simulator (MR-sim) on healthy volunteers. Methods A total of 159 scans of 14 healthy volunteers were conducted on a 1.5-T MR-sim with thermoplastic mask immobilization. MR images with isotropic 1.053 mm3 voxel size were rigidly registered to the first scan based on fiducial, anatomical and gross positions. Mean and standard deviation of positional displacements in translation and rotation were assessed. Systematic error and random errors of positioning in the head and neck on the MR-sim were determined in the translation of, and in the rotation of roll, pitch and yaw. Results The systematic error (Σ) of translation in left-right (LR), anterior-posterior (AP) and superior-inferior (SI) direction was 0.57, 0.22 and 0.26 mm for fiducial displacement, 0.28, 0.10 and 0.52 mm for anatomical displacement, and 0.53, 0.22 and 0.49 mm for gross displacement, respectively. The random error (σ) in corresponding translation direction was 2.07, 0.54 and 1.32 mm for fiducial displacement, 1.34, 0.73 and 2.04 mm for anatomical displacement, and 2.24, 0.86 and 2.61 mm for gross displacement. The systematic error and random error of rotation were generally smaller than 1°. Conclusions Our results suggested that high gross positional reproducibility (<1 mm translational and <1° rotational systematic error) could be achieved on an MR-sim for the proposed offline MRgRT.
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Affiliation(s)
- Yihang Zhou
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Jing Yuan
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Oi Lei Wong
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Winky Wing Ki Fung
- Department of Radiotherapy, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Ka Fai Cheng
- Department of Radiotherapy, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Kin Yin Cheung
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
| | - Siu Ki Yu
- Medical Physics and Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China
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Al-Ward S, Wronski M, Ahmad SB, Myrehaug S, Chu W, Sahgal A, Keller BM. The radiobiological impact of motion tracking of liver, pancreas and kidney SBRT tumors in a MR-linac. Phys Med Biol 2018; 63:215022. [PMID: 30375365 DOI: 10.1088/1361-6560/aae7fd] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The purpose of this work is to evaluate and quantify the potential radiobiological advantages of tumor tracking using the MR-linac for three disease sites: liver, pancreas and kidney. From each disease site, three patients were selected and 4DCT data sets were used. We applied two planning methods using the Monaco treatment planning system (Elekta AB,Stockholm,Sweden): (1) the conventional ITV method using a 6MV Agility beam and (2) a simulated tracking method using MLC GTV tracking with a 7MV MR-linac beam model incorporating a 1.5 T transverse magnetic field. A 5 mm isotropic PTV margin was added to the ITV or the GTV, and 95% of the PTV volume received 100% of the prescription dose. To evaluate the potential radiobiological advantages of tumor tracking, the normal tissue complication probabilities (NTCPs) were calculated for each organ at risk (OAR) using the Layman Kutcher Burman (LKB) model. The average reduction in the target volume, due to tracking, was 31.1%, 26.3% and 26.9% for liver, pancreas and kidney patients, respectively. For each OAR, the % differences in NTCP between the two methods were calculated. The mean 2 Gy equivalent OAR dose for all patients was less than 29.1 Gy, below which the NTCP for most OARs was not sensitive to equivalent uniform dose (EUD). As a result, a NTCP benefit, due to tracking, was observed in 26% of the data. For all three disease sites, the maximum NTCP improvements were for the normal kidney, the bowels, and the duodenum, with reductions in associated toxicities of 79% (radiation nephropathy), 69% (stricture/fistula) and 25% (ulceration), respectively. This study demonstrates the potential benefit of using a MR-linac tracking system to reduce NTCPs. The normal kidney, the bowels and the duodenum showed the largest NTCP improvements. This, in part, is due to the rapid changes in NTCP for small EUD changes.
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Affiliation(s)
- Shahad Al-Ward
- Sunnybrook Health Sciences Centre, Odette Cancer Centre, Toronto, ON, Canada
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Edmund JM, Nyholm T. A review of substitute CT generation for MRI-only radiation therapy. Radiat Oncol 2017; 12:28. [PMID: 28126030 PMCID: PMC5270229 DOI: 10.1186/s13014-016-0747-y] [Citation(s) in RCA: 236] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 12/21/2016] [Indexed: 12/13/2022] Open
Abstract
Radiotherapy based on magnetic resonance imaging as the sole modality (MRI-only RT) is an area of growing scientific interest due to the increasing use of MRI for both target and normal tissue delineation and the development of MR based delivery systems. One major issue in MRI-only RT is the assignment of electron densities (ED) to MRI scans for dose calculation and a similar need for attenuation correction can be found for hybrid PET/MR systems. The ED assigned MRI scan is here named a substitute CT (sCT). In this review, we report on a collection of typical performance values for a number of main approaches encountered in the literature for sCT generation as compared to CT. A literature search in the Scopus database resulted in 254 papers which were included in this investigation. A final number of 50 contributions which fulfilled all inclusion criteria were categorized according to applied method, MRI sequence/contrast involved, number of subjects included and anatomical site investigated. The latter included brain, torso, prostate and phantoms. The contributions geometric and/or dosimetric performance metrics were also noted. The majority of studies are carried out on the brain for 5–10 patients with PET/MR applications in mind using a voxel based method. T1 weighted images are most commonly applied. The overall dosimetric agreement is in the order of 0.3–2.5%. A strict gamma criterion of 1% and 1mm has a range of passing rates from 68 to 94% while less strict criteria show pass rates > 98%. The mean absolute error (MAE) is between 80 and 200 HU for the brain and around 40 HU for the prostate. The Dice score for bone is between 0.5 and 0.95. The specificity and sensitivity is reported in the upper 80s% for both quantities and correctly classified voxels average around 84%. The review shows that a variety of promising approaches exist that seem clinical acceptable even with standard clinical MRI sequences. A consistent reference frame for method benchmarking is probably necessary to move the field further towards a widespread clinical implementation.
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Affiliation(s)
- Jens M Edmund
- Radiotherapy Research Unit, Department of Oncology, Herlev & Gentofte Hospital, Copenhagen University, Herlev, Denmark. .,Niels Bohr Institute, Copenhagen University, Copenhagen, Denmark.
| | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Umeå, SE-901 87, Sweden.,Medical Radiation Physics, Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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Noel CE, Parikh PJ, Spencer CR, Green OL, Hu Y, Mutic S, Olsen JR. Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy. Acta Oncol 2015. [PMID: 26206517 DOI: 10.3109/0284186x.2015.1062541] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT. MATERIAL AND METHODS Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning. RESULTS In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT. CONCLUSION Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.
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Affiliation(s)
- Camille E Noel
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Parag J Parikh
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Christopher R Spencer
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Olga L Green
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Yanle Hu
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Sasa Mutic
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
| | - Jeffrey R Olsen
- a Department of Radiation Oncology , Washington University School of Medicine , St. Louis , Missouri , USA
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Edmund JM, Andreasen D, Mahmood F, Van Leemput K. Cone beam computed tomography guided treatment delivery and planning verification for magnetic resonance imaging only radiotherapy of the brain. Acta Oncol 2015. [PMID: 26198652 DOI: 10.3109/0284186x.2015.1062546] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Radiotherapy based on MRI only (MRI-only RT) shows a promising potential for the brain. Much research focuses on creating a pseudo computed tomography (pCT) from MRI for treatment planning while little attention is often paid to the treatment delivery. Here, we investigate if cone beam CT (CBCT) can be used for MRI-only image-guided radiotherapy (IGRT) and for verifying the correctness of the corresponding pCT. MATERIAL AND METHODS Six patients receiving palliative cranial RT were included in the study. Each patient had three-dimensional (3D) T1W MRI, a CBCT and a CT for reference. Further, a pCT was generated using a patch-based approach. MRI, pCT and CT were placed in the same frame of reference, matched to CBCT and the differences noted. Paired pCT-CT and pCT-CBCT data were created in bins of 10 HU and the absolute difference calculated. The data were converted to relative electron densities (RED) using the CT or a CBCT calibration curve. The latter was either based on a CBCT phantom (phan) or a paired CT-CBCT population (pop) of the five other patients. RESULTS Non-significant (NS) differences in the pooled CT-CBCT, MRI-CBCT and pCT-CBCT transformations were noted. The largest deviations from the CT-CBCT reference were < 1 mm and 1°. The average median absolute error (MeAE) in HU was 184 ± 34 and 299 ± 34 on average for pCT-CT and pCT-CBCT, respectively, and was significantly different (p < 0.01) in each patient. The average MeAE in RED was 0.108 ± 0.025, 0.104 ± 0.011 and 0.099 ± 0.017 for pCT-CT, pCT-CBCT phan (p < 0.01 on 2 patients) and pCT-CBCT pop (NS), respectively. CONCLUSIONS CBCT can be used for patient setup with either MRI or pCT as reference. The correctness of pCT can be verified from CBCT using a population-based calibration curve in the treatment geometry.
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Affiliation(s)
- Jens M Edmund
- a Radiotherapy Research Unit, Department of Oncology , Gentofte and Herlev Hospital, University of Copenhagen , Herlev , Denmark
| | - Daniel Andreasen
- a Radiotherapy Research Unit, Department of Oncology , Gentofte and Herlev Hospital, University of Copenhagen , Herlev , Denmark
- b DTU Compute, Technical University of Denmark , Lyngby , Denmark
| | - Faisal Mahmood
- a Radiotherapy Research Unit, Department of Oncology , Gentofte and Herlev Hospital, University of Copenhagen , Herlev , Denmark
| | - Koen Van Leemput
- b DTU Compute, Technical University of Denmark , Lyngby , Denmark
- c Department of Radiology , Harvard Medical School, Massachusetts General Hospital , Boston , USA
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Doemer A, Chetty IJ, Glide-Hurst C, Nurushev T, Hearshen D, Pantelic M, Traughber M, Kim J, Levin K, Elshaikh MA, Walker E, Movsas B. Evaluating organ delineation, dose calculation and daily localization in an open-MRI simulation workflow for prostate cancer patients. Radiat Oncol 2015; 10:37. [PMID: 25889107 PMCID: PMC4340286 DOI: 10.1186/s13014-014-0309-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 12/15/2014] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND This study describes initial testing and evaluation of a vertical-field open Magnetic Resonance Imaging (MRI) scanner for the purpose of simulation in radiation therapy for prostate cancer. We have evaluated the clinical workflow of using open MRI as a sole modality for simulation and planning. Relevant results related to MRI alignment (vs. CT) reference dataset with Cone-Beam CT (CBCT) for daily localization are presented. METHODS Ten patients participated in an IRB approved study utilizing MRI along with CT simulation with the intent of evaluating the MRI-simulation process. Differences in prostate gland volume, seminal vesicles, and penile bulb were assessed with MRI and compared to CT. To evaluate dose calculation accuracy, bulk-density-assignments were mapped onto respective MRI datasets and treated IMRT plans were re-calculated. For image localization purposes, 400 CBCTs were re-evaluated with MRI as the reference dataset and daily shifts compared against CBCT-to-CT registration. Planning margins based on MRI/CBCT shifts were computed using the van Herk formalism. RESULTS Significant organ contour differences were noted between MRI and CT. Prostate volumes were on average 39.7% (p = 0.002) larger on CT than MRI. No significant difference was found in seminal vesicle volumes (p = 0.454). Penile bulb volumes were 61.1% higher on CT, without statistical significance (p = 0.074). MRI-based dose calculations with assigned bulk densities produced agreement within 1% with heterogeneity corrected CT calculations. The differences in shift positions for the cohort between CBCT-to-CT registration and CBCT-to-MRI registration are -0.15 ± 0.25 cm (anterior-posterior), 0.05 ± 0.19 cm (superior-inferior), and -0.01 ± 0.14 cm (left-right). CONCLUSIONS This study confirms the potential of using an open-field MRI scanner as primary imaging modality for prostate cancer treatment planning simulation, dose calculations and daily image localization.
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Affiliation(s)
- Anthony Doemer
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Indrin J Chetty
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Carri Glide-Hurst
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Teamour Nurushev
- Department of Radiation Oncology, 21st Century Oncology, 28585 Orchard Lake Rd, Suite 110, Farmington Hills, MI, 48334, USA.
| | - David Hearshen
- Department of Radiology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Milan Pantelic
- Department of Radiology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | | | - Joshua Kim
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Kenneth Levin
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Mohamed A Elshaikh
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Eleanor Walker
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
| | - Benjamin Movsas
- Department of Radiation Oncology, Henry Ford Health System, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
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Kim J, Glide-Hurst C, Doemer A, Wen N, Movsas B, Chetty IJ. Implementation of a Novel Algorithm For Generating Synthetic CT Images From Magnetic Resonance Imaging Data Sets for Prostate Cancer Radiation Therapy. Int J Radiat Oncol Biol Phys 2015; 91:39-47. [DOI: 10.1016/j.ijrobp.2014.09.015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 08/15/2014] [Accepted: 09/10/2014] [Indexed: 10/24/2022]
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Eiland RB, Maare C, Sjöström D, Samsøe E, Behrens CF. Dosimetric and geometric evaluation of the use of deformable image registration in adaptive intensity-modulated radiotherapy for head-and-neck cancer. JOURNAL OF RADIATION RESEARCH 2014; 55:1002-1008. [PMID: 24907340 PMCID: PMC4202302 DOI: 10.1093/jrr/rru044] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 05/08/2014] [Accepted: 05/12/2014] [Indexed: 06/03/2023]
Abstract
The aim of this study was to carry out geometric and dosimetric evaluation of the usefulness of a deformable image registration algorithm utilized for adaptive head-and-neck intensity-modulated radiotherapy. Data consisted of seven patients, each with a planning CT (pCT), a rescanning CT (ReCT) and a cone beam CT (CBCT). The CBCT was acquired on the same day (± 1 d) as the ReCT (i.e. at Fraction 17, 18, 23, 24 or 29). The ReCT served as ground truth. A deformed CT (dCT) with structures was created by deforming the pCT to the CBCT. The geometrical comparison was based on the volumes of the deformed, and the manually delineated structures on the ReCT. Likewise, the center of mass shift (CMS) and the Dice similarity coefficient were determined. The dosimetric comparison was performed by recalculating the initial treatment plan on the dCT and the ReCT. Dose-volume histogram (DVH) points and a range of conformity measures were used for the evaluation. We found a significant difference in the median volume of the dCT relative to that of the ReCT. Median CMS values were ∼ 2-5 mm, except for the spinal cord, where the median CMS was 8 mm. Dosimetric evaluation of target structures revealed small differences, while larger differences were observed for organs at risk. The deformed structures cannot fully replace manually delineated structures. Based on both geometrical and dosimetrical measures, there is a tendency for the dCT to overestimate the need for replanning, compared with the ReCT.
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Affiliation(s)
- R B Eiland
- Department of Oncology, Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK2730 Herlev, Denmark
| | - C Maare
- Department of Oncology, Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK2730 Herlev, Denmark
| | - D Sjöström
- Department of Oncology, Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK2730 Herlev, Denmark
| | - E Samsøe
- Department of Oncology, Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK2730 Herlev, Denmark
| | - C F Behrens
- Department of Oncology, Radiotherapy Research Unit, Herlev Hospital, University of Copenhagen, Herlev Ringvej 75, DK2730 Herlev, Denmark
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Nyholm T, Jonsson J, Söderström K, Bergström P, Carlberg A, Frykholm G, Behrens CF, Geertsen PF, Trepiakas R, Hanvey S, Sadozye A, Ansari J, McCallum H, Frew J, McMenemin R, Zackrisson B. Variability in prostate and seminal vesicle delineations defined on magnetic resonance images, a multi-observer, -center and -sequence study. Radiat Oncol 2013; 8:126. [PMID: 23706145 PMCID: PMC3680182 DOI: 10.1186/1748-717x-8-126] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 03/28/2013] [Indexed: 11/22/2022] Open
Abstract
Background The use of magnetic resonance (MR) imaging as a part of preparation for radiotherapy is increasing. For delineation of the prostate several publications have shown decreased delineation variability using MR compared to computed tomography (CT). The purpose of the present work was to investigate the intra- and inter-physician delineation variability for prostate and seminal vesicles, and to investigate the influence of different MR sequence settings used clinically at the five centers participating in the study. Methods MR series from five centers, each providing five patients, were used. Two physicians from each center delineated the prostate and the seminal vesicles on each of the 25 image sets. The variability between the delineations was analyzed with respect to overall, intra- and inter-physician variability, and dependence between variability and origin of the MR images, i.e. the MR sequence used to acquire the data. Results The intra-physician variability in different directions was between 1.3 - 1.9 mm and 3 – 4 mm for the prostate and seminal vesicles respectively (1 std). The inter-physician variability for different directions were between 0.7 – 1.7 mm and approximately equal for the prostate and seminal vesicles. Large differences in variability were observed for individual patients, and also for individual imaging sequences used at the different centers. There was however no indication of decreased variability with higher field strength. Conclusion The overall delineation variability is larger for the seminal vesicles compared to the prostate, due to a larger intra-physician variability. The imaging sequence appears to have a large influence on the variability, even for different variants of the T2-weighted spin-echo based sequences, which were used by all centers in the study.
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Rylander S, Thörnqvist S, Haack S, Pedersen EM, Muren LP. Intensity profile based measurement of prostate gold markers influence on 1.5 and 3T diffusion-weighted MR images. Acta Oncol 2011; 50:866-72. [PMID: 21767186 DOI: 10.3109/0284186x.2011.590523] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND AND PURPOSE In this study the influence of fiducial markers (FMs) on diffusion-weighted (DW) magnetic resonance images was investigated by measuring the intensity variations due to the artefact from the FM image reconstruction. MATERIAL AND METHODS DW- and reference T1W images were acquired of an Agar-gel phantom containing two fixed cylindrical FMs, with a 1.5- and 3T MR scanner. The center of gravity (CoG) positions of the manually segmented FM artefacts (FMA) and the size of FMAs in x-, y- and z direction were measured in the two corresponding image sets, based on the intensity changes caused by the FM reconstruction. Also, a similarity measure, the Dice similarity coefficient (DSC), of the segmented FMAs in the two image sets was calculated. RESULTS The mean shift of the CoG of the manually segmented FMAs in the phase encoding (PE) and the two orthogonal directions, respectively, was: 1.5T/3T; 0.3 ± 0.1/0.5 ± 0.3 cm and 1.5T/3T; 0.1 ± 0.1/0.1 ± 0.1 cm. The largest shift was observed in the 3T DW images for FMs aligned with the long axis orthogonal to the PE direction (0.9 ± 0.1 cm). The mean size of the FMA in the PE- and the two orthogonal directions, respectively, was: 1.5T/3T; 1.7 ± 0.5/1.3 ± 0.1 cm, and 1.5T/3T; 0.9 ± 0.3/1.0 ± 0.2 cm. The mean DSC value of the segmented artefact volumes in the DW- vs. T1W images were 21% and 5% for the 1.5- and 3.0T MR scanner, respectively. CONCLUSIONS This study has shown that both the size and displacement of the FMAs increase in the PE direction on DW images. The larger shifts were observed for FMs positioned with the long axis orthogonal to the PE direction. Measurements obtained for different b-values gave consistent results.
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Affiliation(s)
- Susanne Rylander
- Department of Medical Physics, Aarhus University Hospital, Aarhus, Denmark.
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Lassen-Ramshad Y, Vestergaard A, Muren LP, Høyer M, Petersen JBB. Plan robustness in proton beam therapy of a childhood brain tumour. Acta Oncol 2011; 50:791-6. [PMID: 21767176 DOI: 10.3109/0284186x.2011.590149] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
INTRODUCTION The concern of secondary cancer induction and normal tissue complications have motivated a more frequent use of protons in radiotherapy (RT) of children. However, proton RT is likely to be less robust to anatomical changes occurring during therapy. In this study we present a recent clinical case to illustrate this issue. MATERIAL AND METHODS A five-year-old boy with a highly proliferating malignant intracranial nerve sheath tumour underwent a partial resection prior to RT and developed a post-surgery oedema close to the surgical cavity. RT was delivered with volumetric modulated arc therapy (VMAT) to a total tumour dose of 61.2 Gy. The most critical organs at risk (ORs) were the right optical nerve, brainstem and chiasm. Proton plans were constructed for the purpose of this study. In order to simulate a worst-case scenario, the extent of the oedema observed in the last part of the treatment was used to modify the oedema on the planning computed tomography (CT). Both the photon and proton plans were then re-calculated, as follows: Scenario A: Treatment planning based on the planning CT with oedema and dose calculated as if it was delivered without oedema. Scenario B: Treatment planning on the modified planning CT without oedema, but re-calculated with oedema. These two scenarios were compared to the situation where the oedema was present at treatment planning and unchanged during RT. RESULTS Total dose to critical ORs remained unchanged for the photon plans, with changes within 0.3 Gy for the normal tissues and nearly identical target coverage. For protons, scenario A led to increased maximal doses in all critical ORs, 5.1 Gy in the brainstem, 6.1 Gy in the chiasm and 6.4 Gy in the right optical nerve. For scenario B the proton plans resulted in a loss in target coverage. CONCLUSION This case study shows that RT with protons were far less robust to anatomical changes than when treated with photons, emphasising the increased need for adaptive approaches in RT with protons.
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Ihalainen TM, Lönnroth NT, Peltonen JI, Uusi-Simola JK, Timonen MH, Kuusela LJ, Savolainen SE, Sipilä OE. MRI quality assurance using the ACR phantom in a multi-unit imaging center. Acta Oncol 2011; 50:966-72. [PMID: 21767198 DOI: 10.3109/0284186x.2011.582515] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Magnetic resonance imaging (MRI) instrumentation is vulnerable to technical and image quality problems, and quality assurance is essential. In the studied regional imaging center the long-term quality assurance has been based on MagNET phantom measurements. American College of Radiology (ACR) has an accreditation program including a standardized image quality measurement protocol and phantom. The ACR protocol includes recommended acceptance criteria for clinical sequences and thus provides possibility to assess the clinical relevance of quality assurance. The purpose of this study was to test the ACR MRI phantom in quality assurance of a multi-unit imaging center. MATERIAL AND METHODS The imaging center operates 11 MRI systems of three major manufacturers with field strengths of 3.0 T, 1.5 T and 1.0 T. Images of the ACR phantom were acquired using a head coil following the ACR scanning instructions. Both ACR T1- and T2-weighted sequences as well as T1- and T2-weighted brain sequences in clinical use at each site were acquired. Measurements were performed twice. The images were analyzed and the results were compared with the ACR acceptance levels. RESULTS The acquisition procedure with the ACR phantom was faster than with the MagNET phantoms. On the first and second measurement rounds 91% and 73% of the systems passed the ACR test. Measured slice thickness accuracies were not within the acceptance limits in site T2 sequences. Differences in the high contrast spatial resolution between the ACR and the site sequences were observed. In 3.0 T systems the image intensity uniformity was slightly lower than the ACR acceptance limit. CONCLUSION The ACR method was feasible in quality assurance of a multi-unit imaging center and the ACR protocol could replace the MagNET phantom tests. An automatic analysis of the images will further improve cost-effectiveness and objectiveness of the ACR protocol.
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Topographic Analyses of Shape of Eyes with Pathologic Myopia by High-Resolution Three-Dimensional Magnetic Resonance Imaging. Ophthalmology 2011; 118:1626-37. [DOI: 10.1016/j.ophtha.2011.01.018] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 01/05/2011] [Accepted: 01/06/2011] [Indexed: 11/17/2022] Open
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