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Dürrbeck C, Schulz M, Pflaum L, Kallis K, Geimer T, Abu-Hossin N, Strnad V, Maier A, Fietkau R, Bert C. Estimating follow-up CTs from geometric deformations of catheter implants in interstitial breast brachytherapy: A feasibility study using electromagnetic tracking. Med Phys 2023; 50:5793-5805. [PMID: 37540071 DOI: 10.1002/mp.16659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 06/20/2023] [Accepted: 07/21/2023] [Indexed: 08/05/2023] Open
Abstract
BACKGROUND Electromagnetic tracking (EMT) systems have been shown to provide valuable information on the geometry of catheter implants in breast cancer patients undergoing interstitial brachytherapy (iBT). In the context of an extended patient-specific, pre-treatment verification, EMT can play a key role in determining the potential need and, if applicable, the appropriate time for treatment adaptation. To detect dosimetric shortcomings the relative position between catheters, and target volume and critical structures must be known. Since EMT cannot provide the anatomical context and standard imaging techniques such as cone-beam CT are not yet available in most brachytherapy suites, it is not possible to detect anatomic changes on a daily or fraction basis, so the need for adaptive planning cannot be identified. PURPOSE The aim of this feasibility study is to develop and evaluate a technique capable of estimating follow-up CTs at any time based on the initial treatment planning CT (PCT) and surrogate information about changes of the implant geometry from an EMT system. METHODS A deformation vector field is calculated from two different implant reconstructions acquired in treatment position through EMT, the first immediately after the PCT and the second at another time point during the course of treatment. The calculation is based on discrete displacement vectors of pairs of control and target points. These are extrapolated by means of different radial basis functions in order to cover the entire CT volume. The adequate parameters for the calculation of the deformation field were identified. By warping the PCT according to the deformation field, one obtains an estimated CT (ECT) that reflects the geometric changes. For the proof of concept, ECTs were computed for the time point of the clinical follow-up CT (FCT) that is embedded in the treatment workflow after the fourth fraction. RESULTS ECT and clinical FCTs of 20 patients were compared to each other quantitatively in terms of absolute Hounsfield unit differences in the planning target volume (PTV) and in a convex hull (CH) enclosing the catheters. The median differences were 31.2 and 29.5 HU for the CH and the PTV, respectively. CONCLUSION The proposed ECT approach was able to approximate the "anatomy of the day" and therefore, in principle, allows a dosimetric appraisal of the treatment plan quality before each fraction. In this way, it can contribute to a more detailed patient-specific quality assurance in iBT of the breast and help to identify the timing for a potential treatment adaptation.
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Affiliation(s)
- Christopher Dürrbeck
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
| | - Moritz Schulz
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
| | - Leonie Pflaum
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
- Pattern Recognition Lab, FAU, Erlangen, Germany
| | - Karoline Kallis
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Tobias Geimer
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Pattern Recognition Lab, FAU, Erlangen, Germany
| | - Nadin Abu-Hossin
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
| | - Vratislav Strnad
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
| | | | - Rainer Fietkau
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
| | - Christoph Bert
- Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
- Comprehensive Cancer Center Erlangen-EMN (CCC ER-EMN), Erlangen, Germany
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Hatamikia S, Jaksa L, Kronreif G, Birkfellner W, Kettenbach J, Buschmann M, Lorenz A. Silicone phantoms fabricated with multi-material extrusion 3D printing technology mimicking imaging properties of soft tissues in CT. Z Med Phys 2023:S0939-3889(23)00076-4. [PMID: 37380561 DOI: 10.1016/j.zemedi.2023.05.007] [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: 12/30/2022] [Revised: 05/20/2023] [Accepted: 05/21/2023] [Indexed: 06/30/2023]
Abstract
Recently, 3D printing has been widely used to fabricate medical imaging phantoms. So far, various rigid 3D printable materials have been investigated for their radiological properties and efficiency in imaging phantom fabrication. However, flexible, soft tissue materials are also needed for imaging phantoms for simulating several clinical scenarios where anatomical deformations is important. Recently, various additive manufacturing technologies have been used to produce anatomical models based on extrusion techniques that allow the fabrication of soft tissue materials. To date, there is no systematic study in the literature investigating the radiological properties of silicone rubber materials/fluids for imaging phantoms fabricated directly by extrusion using 3D printing techniques. The aim of this study was to investigate the radiological properties of 3D printed phantoms made of silicone in CT imaging. To achieve this goal, the radiodensity as described as Hounsfield Units (HUs) of several samples composed of three different silicone printing materials were evaluated by changing the infill density to adjust their radiological properties. A comparison of HU values with a Gammex Tissue Characterization Phantom was performed. In addition, a reproducibility analysis was performed by creating several replicas for specific infill densities. A scaled down anatomical model derived from an abdominal CT was also fabricated and the resulting HU values were evaluated. For the three different silicone materials, a spectrum ranging from -639 to +780 HU was obtained on CT at a scan setting of 120 kVp. In addition, using different infill densities, the printed materials were able to achieve a similar radiodensity range as obtained in different tissue-equivalent inserts in the Gammex phantom (238 HU to -673 HU). The reproducibility results showed good agreement between the HU values of the replicas compared to the original samples, confirming the reproducibility of the printed materials. A good agreement was observed between the HU target values in abdominal CT and the HU values of the 3D-printed anatomical phantom in all tissues.
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Affiliation(s)
- Sepideh Hatamikia
- Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria; Research Center for Medical Image Analysis and Artificial Intelligence (MIAAI), Department of Medicine, Danube Private University, Krems, Austria.
| | - Laszlo Jaksa
- Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria
| | - Gernot Kronreif
- Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria
| | - Wolfgang Birkfellner
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria
| | - Joachim Kettenbach
- Institute of Diagnostic, Interventional Radiology and Nuclear Medicine, Landesklinikum Wiener Neustadt, Wiener Neustadt, Austria
| | - Martin Buschmann
- Department of Radiation Oncology, Medical University of Vienna/AKH Wien, Vienna, Austria
| | - Andrea Lorenz
- Austrian Center for Medical Innovation and Technology (ACMIT), Wiener Neustadt, Austria
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3
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Sato K, Yamashiro A, Koyama T. [Material Investigation for the Development of Non-rigid Phantoms for CT-MRI Image Registration]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2022; 78:615-624. [PMID: 35569958 DOI: 10.6009/jjrt.2022-1241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE In radiotherapy, deformable image registration (DIR) has been frequently used in different imaging examinations in recent years. However, no phantom has been established for quality assurance for DIR. In order to develop a non-rigid phantom for accuracy control between CT and MRI images, we investigated the suitability of 3D printing materials and gel materials in this study. METHODS We measured CT values, T1 values, T2 values, and the proton densities of 31 3D printer materials-purchased from three manufacturers-and one gel material. The dice coefficient after DIR was calculated for the CT-MRI images using a prototype phantom made of a gel material compatible with CT-MRI. RESULTS The CT number of the 3D printing materials ranged from -6.8 to 146.4 HU. On MRI, T1 values were not measurable in most cases, whereas T2 values were not measurable in all cases; proton density (PD) ranged from 2.51% to 4.9%. The gel material had a CT number of 111.16 HU, T1 value of 813.65 ms, and T2 value of 27.19 ms. The prototype phantom was flexible, and the usefulness of DIR with CT and MRI images was demonstrated using this phantom. CONCLUSION The CT number and T1 and T2 values of the gel material are close to those of the human body and may therefore be developed as a DIR verification phantom between CT and MRI. These findings may contribute to the development of non-rigid phantoms for DIR in the future.
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Affiliation(s)
- Kazuki Sato
- Department of Radiology, Nagano Red Cross Hospital
| | - Akihiro Yamashiro
- Department of Radiology, Nagano Red Cross Hospital.,Division of Health Sciences, Graduate School of Medical Sciences, Kanazawa University
| | - Tomio Koyama
- Department of Radiation Oncology, Nagano Red Cross Hospital
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Bauer DF, Rosenkranz J, Golla AK, Tönnes C, Hermann I, Russ T, Kabelitz G, Rothfuss AJ, Schad LR, Stallkamp JL, Zöllner FG. Development of an abdominal phantom for the validation of an oligometastatic disease diagnosis workflow. Med Phys 2022; 49:4445-4454. [PMID: 35510908 DOI: 10.1002/mp.15701] [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: 05/19/2021] [Revised: 12/01/2021] [Accepted: 04/14/2022] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The liver is a common site for metastatic disease, which is a challenging and life-threatening condition with a grim prognosis and outcome. We propose a standardized workflow for the diagnosis of oligometastatic disease (OMD), as a gold standard workflow has not been established yet. The envisioned workflow comprises the acquisition of a multimodal image dataset, novel image processing techniques, and cone beam computed tomography (CBCT)-guided biopsy for subsequent molecular subtyping. By combining morphological, molecular, and functional information about the tumor, a patient-specific treatment planning is possible. We designed and manufactured an abdominal liver phantom that we used to demonstrate multimodal image acquisition, image processing, and biopsy of the OMD diagnosis workflow. METHODS The anthropomorphic abdominal phantom contains a rib cage, a portal vein, lungs, a liver with six lesions, and a hepatic vessel tree. This phantom incorporates three different lesion types with varying visibility under computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography CT (PET-CT), which reflects clinical reality. The phantom is puncturable and the size of the corpus and the organs is comparable to those of a real human abdomen. By using several modern additive manufacturing techniques, the manufacturing process is reproducible and allows to incorporate patient-specific anatomies. As a first step of the OMD diagnosis workflow, a pre-interventional CT, MRI, and PET-CT dataset of the phantom was acquired. The image information was fused using image registration and organ information was extracted via image segmentation. A CBCT-guided needle puncture experiment was performed, where all six liver lesions were punctured with coaxial biopsy needles. RESULTS Qualitative observation of the image data and quantitative evaluation using contrast-to-noise ratio (CNR) confirms that one lesion type is visible only in MRI and not CT. The other two lesion types are visible in CT and MRI. The CBCT-guided needle placement was performed for all six lesions, including those visible only in MRI and not CBCT. This was possible by successfully merging multimodal pre-interventional image data. Lungs, bones, and liver vessels serve as realistic inhibitions during needle path planning. CONCLUSIONS We have developed a reusable abdominal phantom that has been used to validate a standardized OMD diagnosis workflow. Utilizing the phantom, we have been able to show that a multimodal imaging pipeline is advantageous for a comprehensive detection of liver lesions. In a CBCT-guided needle placement experiment we have punctured lesions that are invisible in CBCT using registered pre-interventional MRI scans for needle path planning. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Dominik F Bauer
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Julian Rosenkranz
- Fraunhofer Institute for Manufacturing Engineering and Automation, Department of Clinical Health Technologies, Mannheim, Germany
| | - Alena-Kathrin Golla
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Christian Tönnes
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Ingo Hermann
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Tom Russ
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Gordian Kabelitz
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | - Lothar R Schad
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jan L Stallkamp
- Automation in Medicine and Biotechnology, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank G Zöllner
- Computer Assisted Clinical Medicine, Mannheim Institute for Intelligent Systems in Medicine, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Cloutier E, Beaulieu L, Archambault L. Deformable scintillation dosimeter: II. Real-time simultaneous measurements of dose and tracking of deformation vector fields. Phys Med Biol 2021; 66. [PMID: 34380121 DOI: 10.1088/1361-6560/ac1ca2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 08/11/2021] [Indexed: 12/29/2022]
Abstract
Anatomical motion and deformation pose challenges to the understanding of the delivered dose distribution during radiotherapy treatments. Hence, deformable image registration (DIR) algorithms are increasingly used to map contours and dose distributions from one image set to another. However, the lack of validation tools slows their clinical adoption, despite their commercial availability. This work presents a novel water-equivalent deformable dosimeter that simultaneously measures the dose distribution and tracks deformation vector fields (DVF). The dosimeter in made of an array of 19 scintillating fiber detectors embedded in a cylindrical elastomer matrix. It is imaged by two pairs of stereoscopic cameras tracking the position and angulation of the scintillators, while measuring the dose. The resulting system provides a precision of 0.3 mm on DVF measurements. The dosimeter was irradiated with 5 × 3, 4 × 3 and 3 × 3 cm26 MV photon beams in both fixed and deformed conditions. The measured DVF was compared to the one computed with a DIR algorithm (Plastimatch). The deviations between the computed and measured DVFs was below 1.5 mm. As for dose measurements, the dosimeter acquired the dose distribution in fixed and deformed conditions within 1% of the treatment planning system calculation and complementary dose validation using the Hyperscint dosimetry system. Using the demonstrated qualities of scintillating detectors, we developed a real-time, water-equivalent deformable dosimeter. Given it's sensor tracking position precision and dose measurements accuracy, the developed detector is a promising tools for the validation of DIR algorithms as well as dose distribution measurements under fixed and deformed conditions.
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Affiliation(s)
- E Cloutier
- Service de physique médicale et Axe Oncologie du Centre de recherche, CHU de Québec-Université Laval, Canada.,Département de physique, de génie physique et d'optique, et Centre de recherche sur le cancer, Université Laval, Québec, Canada
| | - L Beaulieu
- Service de physique médicale et Axe Oncologie du Centre de recherche, CHU de Québec-Université Laval, Canada.,Département de physique, de génie physique et d'optique, et Centre de recherche sur le cancer, Université Laval, Québec, Canada
| | - L Archambault
- Service de physique médicale et Axe Oncologie du Centre de recherche, CHU de Québec-Université Laval, Canada.,Département de physique, de génie physique et d'optique, et Centre de recherche sur le cancer, Université Laval, Québec, Canada
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Rong Y, Rosu-Bubulac M, Benedict SH, Cui Y, Ruo R, Connell T, Kashani R, Latifi K, Chen Q, Geng H, Sohn J, Xiao Y. Rigid and Deformable Image Registration for Radiation Therapy: A Self-Study Evaluation Guide for NRG Oncology Clinical Trial Participation. Pract Radiat Oncol 2021; 11:282-298. [PMID: 33662576 PMCID: PMC8406084 DOI: 10.1016/j.prro.2021.02.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/05/2021] [Accepted: 02/16/2021] [Indexed: 02/08/2023]
Abstract
PURPOSE The registration of multiple imaging studies to radiation therapy computed tomography simulation, including magnetic resonance imaging, positron emission tomography-computed tomography, etc. is a widely used strategy in radiation oncology treatment planning, and these registrations have valuable roles in image guidance, dose composition/accumulation, and treatment delivery adaptation. The NRG Oncology Medical Physics subcommittee formed a working group to investigate feasible workflows for a self-study credentialing process of image registration commissioning. METHODS AND MATERIALS The American Association of Physicists in Medicine (AAPM) Task Group 132 (TG132) report on the use of image registration and fusion algorithms in radiation therapy provides basic guidelines for quality assurance and quality control of the image registration algorithms and the overall clinical process. The report recommends a series of tests and the corresponding metrics that should be evaluated and reported during commissioning and routine quality assurance, as well as a set of recommendations for vendors. The NRG Oncology medical physics subcommittee working group found incompatibility of some digital phantoms with commercial systems. Thus, there is still a need to provide further recommendations in terms of compatible digital phantoms, clinical feasible workflow, and achievable thresholds, especially for future clinical trials involving deformable image registration algorithms. Nine institutions participated and evaluated 4 commonly used commercial imaging registration software and various versions in the field of radiation oncology. RESULTS AND CONCLUSIONS The NRG Oncology Working Group on image registration commissioning herein provides recommendations on the use of digital phantom/data sets and analytical software access for institutions and clinics to perform their own self-study evaluation of commercial imaging systems that might be employed for coregistration in radiation therapy treatment planning and image guidance procedures. Evaluation metrics and their corresponding values were given as guidelines to establish practical tolerances. Vendor compliance for image registration commissioning was evaluated, and recommendations were given for future development.
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Affiliation(s)
- Yi Rong
- Department of Radiation Oncology, University of California Davis Cancer Center, Sacramento, California; Department of Radiation Oncology, Mayo Clinic Arizona, Phoenix, Arizona.
| | - Mihaela Rosu-Bubulac
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia
| | - Stanley H Benedict
- Department of Radiation Oncology, University of California Davis Cancer Center, Sacramento, California
| | - Yunfeng Cui
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Russell Ruo
- Department of Medical Physics, McGill University Health Center, Montreal, QC, Canada
| | - Tanner Connell
- Department of Medical Physics, McGill University Health Center, Montreal, QC, Canada
| | - Rojano Kashani
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan
| | - Kujtim Latifi
- Department of Radiation Oncology, H. Lee Moffitt Cancer Center, Tampa, Florida
| | - Quan Chen
- Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky
| | - Huaizhi Geng
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason Sohn
- Department of Radiation Oncology, Allegheny Health Network, Pittsburgh, Pennsylvania
| | - Ying Xiao
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
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Hussein M, Akintonde A, McClelland J, Speight R, Clark CH. Clinical use, challenges, and barriers to implementation of deformable image registration in radiotherapy - the need for guidance and QA tools. Br J Radiol 2021; 94:20210001. [PMID: 33882253 PMCID: PMC8173691 DOI: 10.1259/bjr.20210001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 04/06/2021] [Accepted: 04/12/2021] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE The aim of this study was to evaluate the current status of the clinical use of deformable image registration (DIR) in radiotherapy and to gain an understanding of the challenges faced by centres in clinical implementation of DIR, including commissioning and quality assurance (QA), and to determine the barriers faced. The goal was to inform whether additional guidance and QA tools were needed. METHODS A survey focussed on clinical use, metrics used, how centres would like to use DIR in the future and challenges faced, was designed and sent to 71 radiotherapy centres in the UK. Data were gathered specifically on which centres we using DIR clinically, which applications were being used, what commissioning and QA tests were performed, and what barriers were preventing the integration of DIR into the clinical workflow. Centres that did not use DIR clinically were encouraged to fill in the survey and were asked if they have any future plans and in what timescale. RESULTS 51 out of 71 (70%) radiotherapy centres responded. 47 centres reported access to a commercial software that could perform DIR. 20 centres already used DIR clinically, and 22 centres had plans to implement an application of DIR within 3 years of the survey. The most common clinical application of DIR was to propagate contours from one scan to another (19 centres). In each of the applications, the types of commissioning and QA tests performed varied depending on the type of application and between centres. Some of the key barriers were determining when a DIR was satisfactory including which metrics to use, and lack of resources. CONCLUSION The survey results highlighted that there is a need for additional guidelines, training, better tools for commissioning DIR software and for the QA of registration results, which should include developing or recommending which quantitative metrics to use. ADVANCES IN KNOWLEDGE This survey has given a useful picture of the clinical use and lack of use of DIR in UK radiotherapy centres. The survey provided useful insight into how centres commission and QA DIR applications, especially the variability among centres. It was also possible to highlight key barriers to implementation and determine factors that may help overcome this which include the need for additional guidance specific to different applications, better tools and metrics.
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Affiliation(s)
- Mohammad Hussein
- Metrology for Medical Physics Centre, National Physical Laboratory, Teddington, UK
| | - Adeyemi Akintonde
- Centre for Medical Image Computing, University College London, London, UK
| | - Jamie McClelland
- Centre for Medical Image Computing, University College London, London, UK
| | - Richard Speight
- Leeds Cancer Centre, Leeds Teaching Hospitals NHS Trust, Leeds, UK
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8
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The status of medical physics in radiotherapy in China. Phys Med 2021; 85:147-157. [PMID: 34010803 DOI: 10.1016/j.ejmp.2021.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 05/01/2021] [Accepted: 05/03/2021] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To present an overview of the status of medical physics in radiotherapy in China, including facilities and devices, occupation, education, research, etc. MATERIALS AND METHODS: The information about medical physics in clinics was obtained from the 9-th nationwide survey conducted by the China Society for Radiation Oncology in 2019. The data of medical physics in education and research was collected from the publications of the official and professional organizations. RESULTS By 2019, there were 1463 hospitals or institutes registered to practice radiotherapy and the number of accelerators per million population was 1.5. There were 4172 medical physicists working in clinics of radiation oncology. The ratio between the numbers of radiation oncologists and medical physicists is 3.51. Approximately, 95% of medical physicists have an undergraduate or graduate degrees in nuclear physics and biomedical engineering. 86% of medical physicists have certificates issued by the Chinese Society of Medical Physics. There has been a fast growth of publications by authors from mainland of China in the top international medical physics and radiotherapy journals since 2018. CONCLUSIONS Demand for medical physicists in radiotherapy increased quickly in the past decade. The distribution of radiotherapy facilities in China became more balanced. High quality continuing education and training programs for medical physicists are deficient in most areas. The role of medical physicists in the clinic has not been clearly defined and their contributions have not been fully recognized by the community.
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Matrosic CK, Culberson W, Shepard A, Jupitz S, Bednarz B. 3D dosimetric validation of ultrasound-guided radiotherapy with a dynamically deformable abdominal phantom. Phys Med 2021; 84:159-167. [PMID: 33901860 DOI: 10.1016/j.ejmp.2021.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/01/2021] [Accepted: 04/06/2021] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVES The purpose of this study was to dosimetrically benchmark gel dosimetry measurements in a dynamically deformable abdominal phantom for intrafraction image guidance through a multi-dosimeter comparison. Once benchmarked, the study aimed to perform a proof-of-principle study for validation measurements of an ultrasound image-guided radiotherapy delivery system. METHODS The phantom was dosimetrically benchmarked by delivering a liver VMAT plan and measuring the 3D dose distribution with DEFGEL dosimeters. Measured doses were compared to the treatment planning system and measurements acquired with radiochromic film and an ion chamber. The ultrasound image guidance validation was performed for a hands-free ultrasound transducer for the tracking of liver motion during treatment. RESULTS Gel dosimeters were compared to the TPS and film measurements, showing good qualitative dose distribution matches, low γ values through most of the high dose region, and average 3%/5 mm γ-analysis pass rates of 99.2%(0.8%) and 90.1%(0.8%), respectively. Gel dosimeter measurements matched ion chamber measurements within 3%. The image guidance validation study showed the measurement of the treatment delivery improvements due to the inclusion of the ultrasound image guidance system. Good qualitative matching of dose distributions and improvements of the γ-analysis results were observed for the ultrasound-gated dosimeter compared to the ungated dosimeter. CONCLUSIONS DEFGEL dosimeters in phantom showed good agreement with the planned dose and other dosimeters for dosimetric benchmarking. Ultrasound image guidance validation measurements showed good proof-of-principle of the utility of the phantom system as a method of validating ultrasound-based image guidance systems and potentially other image guidance methods.
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Affiliation(s)
- Charles K Matrosic
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States.
| | - Wesley Culberson
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Andrew Shepard
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Sydney Jupitz
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
| | - Bryan Bednarz
- School of Medicine and Public Health, Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, United States
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Sarria GR, Schmitt H, Jahnke L, Bürgy D, Wenz F, Siebenlist K, Giordano FA, Jahnke A, Boda-Heggemann J. Cone Beam CT-Based Daily Adaptive Planning or Defined-Filling Protocol for Neoadjuvant Gastric Cancer Radiation Therapy: A Comparison. Adv Radiat Oncol 2021; 6:100593. [PMID: 33490728 PMCID: PMC7811127 DOI: 10.1016/j.adro.2020.09.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/30/2020] [Indexed: 10/26/2022] Open
Abstract
Purpose This study aimed to investigate, in the setting of neoadjuvant gastric irradiation with integrated boost, whether cone beam computed tomography (CBCT)-based adaptive radiation therapy compared with a defined-filling protocol would be beneficial in terms of feasibility and achieving daily reproducible dose volume indexes of the planning target volume (PTV) and organs at risk (OARs) and workflow. Methods and materials Planning computed tomography (PCT) and 25 CBCT scans of a previously treated patient were used, and neoadjuvant therapy of gastric carcinoma was simulated offline. PTVs and OARs were defined per the TOPGEAR protocol (PTV: 45 Gy/1.8 Gy), and an integrated boost (gross tumor volume [GTV]: 50.4 Gy/2.016 Gy) was added. The patient followed a filling regimen consisting of 12-hour fasting followed by 200 mL of water intake (2 glasses of water) immediately before irradiation. OARs and PTVs were newly contoured on each CBCT. Nonrigid registration of PCT and CBCT scans was performed. Nonadapted plans were recalculated on each CBCT (R-CBCT). Furthermore, an adapted plan was created for the new anatomy (A-CBCT). Dose parameters and comparison of R-CBCT and A-CBCT for the kidneys, liver, and heart were analyzed using a paired t test. Results A total of 200 plans for R-CBCT and A-CBCT were obtained. Mean gastric volumes were 277.32 cm3 (±54.40 cm3) in CBCT scans and 519.2 cm3 in PCT. Mean doses to the PTV did not differ meaningfully within the CBCT scans, with an average of 1.54%. The D95 improved in GTV coverage by 5.26% compared with the R-CBCT plan. Mean heart, liver, and right kidney doses were reduced with the A-CBCT plan by 35.74%, 10.71% and 29.47%, respectively. The R- and A-CBCT comparison for GTV and OARs was significantly different in all cases (P < .0001). Conclusions Adaptive radiation therapy through deformable registration represents an important tool in neoadjuvant gastric irradiation, encompassing daily variability and organ motion, compared with the defined-filling protocol while improving OAR sparing.
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Affiliation(s)
- Gustavo R Sarria
- Department of Radiation Oncology, University Hostpital Bonn, University of Bonn, Bonn, Germany
| | - Hanna Schmitt
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Lennart Jahnke
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,University Heart Center Freiburg, University Medical Center Freiburg, Medical Faculty Freiburg, Freiburg University, Freiburg, Germany
| | - Daniel Bürgy
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frederik Wenz
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,University Medical Center Freiburg, Medical Faculty Freiburg, Freiburg University, Freiburg, Germany
| | - Kerstin Siebenlist
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank A Giordano
- Department of Radiation Oncology, University Hostpital Bonn, University of Bonn, Bonn, Germany
| | - Anika Jahnke
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.,Institute for Digitalization in Medicine, University Medical Center Freiburg, Medical Faculty Freiburg, Freiburg University, Freiburg, Germany
| | - Judit Boda-Heggemann
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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11
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Glide-Hurst CK, Lee P, Yock AD, Olsen JR, Cao M, Siddiqui F, Parker W, Doemer A, Rong Y, Kishan AU, Benedict SH, Li XA, Erickson BA, Sohn JW, Xiao Y, Wuthrick E. Adaptive Radiation Therapy (ART) Strategies and Technical Considerations: A State of the ART Review From NRG Oncology. Int J Radiat Oncol Biol Phys 2020; 109:1054-1075. [PMID: 33470210 DOI: 10.1016/j.ijrobp.2020.10.021] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 10/08/2020] [Accepted: 10/19/2020] [Indexed: 12/21/2022]
Abstract
The integration of adaptive radiation therapy (ART), or modifying the treatment plan during the treatment course, is becoming more widely available in clinical practice. ART offers strong potential for minimizing treatment-related toxicity while escalating or de-escalating target doses based on the dose to organs at risk. Yet, ART workflows add complexity into the radiation therapy planning and delivery process that may introduce additional uncertainties. This work sought to review presently available ART workflows and technological considerations such as image quality, deformable image registration, and dose accumulation. Quality assurance considerations for ART components and minimum recommendations are described. Personnel and workflow efficiency recommendations are provided, as is a summary of currently available clinical evidence supporting the implementation of ART. Finally, to guide future clinical trial protocols, an example ART physician directive and a physics template following standard NRG Oncology protocol is provided.
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Affiliation(s)
- Carri K Glide-Hurst
- Department of Human Oncology, University of Wisconsin-Madison, Madison, Wisconsin.
| | - Percy Lee
- Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Adam D Yock
- Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Jeffrey R Olsen
- Department of Radiation Oncology, University of Colorado- Denver, Denver, Colorado
| | - Minsong Cao
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, California
| | - Farzan Siddiqui
- Department of Radiation Oncology, Henry Ford Cancer Institute, Detroit, Michigan
| | - William Parker
- Department of Radiation Oncology, McGill University, Montreal, Quebec, Canada
| | - Anthony Doemer
- Department of Radiation Oncology, Henry Ford Cancer Institute, Detroit, Michigan
| | - Yi Rong
- Department of Radiation Oncology, University of California-Davis, Sacramento, California
| | - Amar U Kishan
- Department of Radiation Oncology, University of California-Los Angeles, Los Angeles, California
| | - Stanley H Benedict
- Department of Radiation Oncology, University of California-Davis, Sacramento, California
| | - X Allen Li
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Beth A Erickson
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Jason W Sohn
- Department of Radiation Oncology, Allegheny Health Network, Pittsburgh, Pennsylvania
| | - Ying Xiao
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Evan Wuthrick
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida
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12
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Sugawara Y, Kadoya N, Kotabe K, Nakajima Y, Ikeda R, Tanabe S, Ohashi H, Jingu K. Development of a dynamic deformable thorax phantom for the quality management of deformable image registration. Phys Med 2020; 77:100-107. [PMID: 32823209 DOI: 10.1016/j.ejmp.2020.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/07/2020] [Accepted: 08/07/2020] [Indexed: 11/26/2022] Open
Abstract
The purpose of this study was to develop a novel dynamic deformable thorax phantom for deformable image registration (DIR) quality assurance (QA) and to verify as a tool for commissioning and DIR QA. The phantom consists of a base phantom, an inner phantom, and a motor-derived piston. The base phantom is an acrylic cylinder phantom with a diameter of 180 mm. The inner phantom consists of deformable, 20 mm thick disk-shaped sponges. To evaluate the physical characteristics of the phantom, we evaluated its image quality and deformation. DIR accuracies were evaluated using the three types of commercially DIR software (MIM, RayStation, and Velocity AI) to test the feasibility of this phantom. We used different DIR parameters to test the impact of parameters on DIR accuracy in various phantom settings. To evaluate DIR accuracy, a target registration error (TRE) was calculated using the anatomical landmark points. The three locations (i.e., distal, middle, and proximal positions) had different displacement amounts. This result indicated that the inner phantom was not moved but deformed. In cases with different phantom settings and marker settings, the ranges of the average TRE were 0.63-15.60 mm (MIM). In cases with different DIR parameters settings, the ranges of the average TRE were as follows: 0.73-7.10 mm (MIM), 8.25-8.66 mm (RayStation), and 8.26-8.43 mm (Velocity). These results suggest that our phantom could evaluate the detailed DIR behaviors with TRE. Therefore, this is indicative of the potential usefulness of our phantom in DIR commissioning and QA.
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Affiliation(s)
- Yasuharu Sugawara
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan; Department of Radiology, Center Hospital of National Center for Global Health and Medicine, Tokyo, Japan
| | - Noriyuki Kadoya
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
| | - Kazuki Kotabe
- Department of Radiology, Center Hospital of National Center for Global Health and Medicine, Tokyo, Japan
| | - Yujiro Nakajima
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan; Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
| | - Ryutaro Ikeda
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan; Department of Radiology, Ishinomaki Red-Cross Hospital, Miyagi, Japan
| | - Shunpei Tanabe
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Haruna Ohashi
- Course of Radiological Technology, Health Sciences, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
| | - Keiichi Jingu
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Miyagi, Japan
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13
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Matrosic CK, Bednarz B, Culberson W. An improved abdominal phantom for intrafraction image guidance validation. Phys Med Biol 2020; 65:13NT02. [PMID: 32428876 DOI: 10.1088/1361-6560/ab9456] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A dynamically compressible phantom of the human abdomen that simulates organ motion with breathing is being developed for possible testing of image-gated beam delivery in radiotherapy. The polyvinyl chloride plastisol (PVCP) phantom features a cavity that can contain a deformable normoxic polyacrylamide gel (nPAG) dosimeter that is intended for use with MRI to provide dosimetric data. The phantom has been improved by the inclusion of new components that are more realistic anatomically and exhibit CT values similar to those of the tissues they mimic. Component organs were made from 3D-printed molds developed from CT contours of a real patient and their radiodensities adjusted by varying the mass ratios of the PVCP hardener and softener during manufacture. To make the phantom more compatible with ultrasound imaging a graphite scatterer was mixed into some of the phantom components to produce a background speckle pattern. This provided contrast between the body and a moving anatomical target intended for motion tracking. Phantom insert motion magnitude and repeatibility was assessed using CT by imaging two phantom inserts, one containing fiducial markers and the other containing iodinated gelatin, at the same position after repeated cycles of deformation. The maximum motion of a phantom fiducial at the position of the phantom treatment target was found to be 12.2 mm. The phantom design resulted in dosimeter motion with a point-to-point repatability within 0.3 mm on average and contour repeatability resulting in Dice coefficients exceeding 0.98 on average.
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Affiliation(s)
- Charles K Matrosic
- School of Medicine and Public Health Department of Medical Physics, University of Wisconsin, Madison, WI, United States of America. Department of Radiation Oncology, University of Michigan, Ann Arbor, MI, United States of America
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14
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Romanò C, De Marco P, Trivellato S, Ciardo D, Comi S, Marvaso G, Riva G, Jereczek-Fossa BA, Orecchia R, Cattani F. Influence of different urinary bladder filling levels and controlling regions of interest selection on deformable image registration algorithms. Phys Med 2020; 75:19-25. [PMID: 32473519 DOI: 10.1016/j.ejmp.2020.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/01/2020] [Accepted: 05/12/2020] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Evaluation of Raystation ANAtomically CONstrained Deformation Algorithm (ANACONDA) performance to different urinary bladder filling levels in male pelvis anatomic site varying the controlling Regions Of Interest (ROIs). METHODS Different image datasets were obtained with ImSimQA (Oncology System Limited, Shrewsbury, UK) to evaluate ANACONDA performances (RaySearch Laboratories, Stockholm, Sweden). Deformation vector fields were applied to a synthetic man pelvis and a real patient computed tomography (CT) dataset (reference CTs) resulting in deformed CTs (target CTs) with various bladder filling levels. Different deformable image registrations (DIRs) were generated between each target CTs and reference CTs varying the controlling ROIs subset. Deformed ROIs were mapped from target CT to reference CT and then compared to reference ROIs. Evaluation was performed by Dice Similarity Coefficient (DSC), Correlation Coefficient (CC), Mean Distance to Agreement (MDA), maximum Distance to Agreement (maxDA) and with the introduction of global DSC (global_DSC) and global CC (global_CC) parameters. RESULTS In both synthetic and real patient CT cases, DSC scored less than 0.75 and MDA greater than 3 mm when no ROIs or only bladder were exploited as controlling ROI. DSC and CC increased by increasing the number of controlling ROIs selected whereas, an opposite behavior was observed for MDA and maxDA. CONCLUSIONS ANACONDA performances can be influenced by bladder filling fluctuation if no controlling ROIs are selected. Global_DSC and global_CC are useful parameters to quantitatively compare DIR algorithms. DIR performances improve by increasing the number of controlling ROIs selected, reaching a saturation level after a defined ROIs subset selection.
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Affiliation(s)
- Chiara Romanò
- Unit of Medical Physics, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy; Department of Physics, University of Milan, Via Festa del Perdono, 7, 20122 Milan, Italy.
| | - Paolo De Marco
- Unit of Medical Physics, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Sara Trivellato
- Unit of Medical Physics, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Delia Ciardo
- Division of Radiation Oncology, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Stefania Comi
- Unit of Medical Physics, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Giulia Marvaso
- Division of Radiation Oncology, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Giulia Riva
- Division of Radiation Oncology, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Barbara Alicja Jereczek-Fossa
- Division of Radiation Oncology, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy; Department of Oncology and Hemato-oncology, University of Milan, Via Festa del Perdono, 7, 20122 Milan, Italy
| | - Roberto Orecchia
- Scientific Directorate, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
| | - Federica Cattani
- Unit of Medical Physics, IEO, European Institute of Oncology IRCCS, Via Ripamonti 435, I 20132 Milan, Italy
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15
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Mittauer KE, Hill PM, Bassetti MF, Bayouth JE. Validation of an MR-guided online adaptive radiotherapy (MRgoART) program: Deformation accuracy in a heterogeneous, deformable, anthropomorphic phantom. Radiother Oncol 2020; 146:97-109. [DOI: 10.1016/j.radonc.2020.02.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/12/2020] [Accepted: 02/15/2020] [Indexed: 01/11/2023]
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16
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Tino R, Yeo A, Leary M, Brandt M, Kron T. A Systematic Review on 3D-Printed Imaging and Dosimetry Phantoms in Radiation Therapy. Technol Cancer Res Treat 2020; 18:1533033819870208. [PMID: 31514632 PMCID: PMC6856980 DOI: 10.1177/1533033819870208] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Additive manufacturing or 3-dimensional printing has become a widespread technology with many applications in medicine. We have conducted a systematic review of its application in radiation oncology with a particular emphasis on the creation of phantoms for image quality assessment and radiation dosimetry. Traditionally used phantoms for quality assurance in radiotherapy are often constraint by simplified geometry and homogenous nature to perform imaging analysis or pretreatment dosimetric verification. Such phantoms are limited due to their ability in only representing the average human body, not only in proportion and radiation properties but also do not accommodate pathological features. These limiting factors restrict the patient-specific quality assurance process to verify image-guided positioning accuracy and/or dose accuracy in "water-like" condition. METHODS AND RESULTS English speaking manuscripts published since 2008 were searched in 5 databases (Google Scholar, Scopus, PubMed, IEEE Xplore, and Web of Science). A significant increase in publications over the 10 years was observed with imaging and dosimetry phantoms about the same total number (52 vs 50). Key features of additive manufacturing are the customization with creation of realistic pathology as well as the ability to vary density and as such contrast. Commonly used printing materials, such as polylactic acid, acrylonitrile butadiene styrene, high-impact polystyrene and many more, are utilized to achieve a wide range of achievable X-ray attenuation values from -1000 HU to 500 HU and higher. Not surprisingly, multimaterial printing using the polymer jetting technology is emerging as an important printing process with its ability to create heterogeneous phantoms for dosimetry in radiotherapy. CONCLUSION Given the flexibility and increasing availability and low cost of additive manufacturing, it can be expected that its applications for radiation medicine will continue to increase.
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Affiliation(s)
- Rance Tino
- RMIT Centre for Additive Manufacture, Innovative Manufacturing Research Group (Medical Manufacturing), RMIT University, Melbourne, Australia.,ARC Industrial Transformation Training Centre in Additive Biomanufacturing, Queensland University of Technology, Brisbane, Australia.,Physical Sciences Department, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Adam Yeo
- Physical Sciences Department, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Martin Leary
- RMIT Centre for Additive Manufacture, Innovative Manufacturing Research Group (Medical Manufacturing), RMIT University, Melbourne, Australia.,ARC Industrial Transformation Training Centre in Additive Biomanufacturing, Queensland University of Technology, Brisbane, Australia
| | - Milan Brandt
- RMIT Centre for Additive Manufacture, Innovative Manufacturing Research Group (Medical Manufacturing), RMIT University, Melbourne, Australia.,ARC Industrial Transformation Training Centre in Additive Biomanufacturing, Queensland University of Technology, Brisbane, Australia
| | - Tomas Kron
- ARC Industrial Transformation Training Centre in Additive Biomanufacturing, Queensland University of Technology, Brisbane, Australia.,Physical Sciences Department, Peter MacCallum Cancer Centre, Melbourne, Australia
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17
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An overview on 3D printing for abdominal surgery. Surg Endosc 2019; 34:1-13. [PMID: 31605218 DOI: 10.1007/s00464-019-07155-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 09/24/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND Three-dimensional (3D) printing is a disruptive technology that is quickly spreading to many fields, including healthcare. In this context, it allows the creation of graspable, patient-specific, anatomical models generated from medical images. The ability to hold and show a physical object speeds up and facilitates the understanding of anatomical details, eases patient counseling and contributes to the education and training of students and residents. Several medical specialties are currently exploring the potential of this technology, including general surgery. METHODS In this review, we provide an overview on the available 3D printing technologies, together with a systematic analysis of the medical literature dedicated to its application for abdominal surgery. Our experience with the first clinical laboratory for 3D printing in Italy is also reported. RESULTS There was a tenfold increase in the number of publications per year over the last decade. About 70% of these papers focused on kidney and liver models, produced primarily for pre-interventional planning, as well as for educational and training purposes. The most used printing technologies are material jetting and material extrusion. Seventy-three percent of publications reported on fewer than ten clinical cases. CONCLUSION The increasing application of 3D printing in abdominal surgery reflects the dawn of a new technology, although it is still in its infancy. The potential benefit of this technology is clear, however, and it may soon lead to the development of new hospital facilities to improve surgical training, research, and patient care.
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18
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Matrosic CK, Hull J, Palmer B, Culberson W, Bednarz B. Deformable abdominal phantom for the validation of real-time image guidance and deformable dose accumulation. J Appl Clin Med Phys 2019; 20:122-133. [PMID: 31355997 PMCID: PMC6698755 DOI: 10.1002/acm2.12687] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 06/03/2019] [Accepted: 07/06/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE End-to-end testing with quality assurance (QA) phantoms for deformable dose accumulation and real-time image-guided radiotherapy (IGRT) has recently been recommended by American Association of Physicists in Medicine (AAPM) Task Groups 132 and 76. The goal of this work was to develop a deformable abdominal phantom containing a deformable three-dimensional dosimeter that could provide robust testing of these systems. METHODS The deformable abdominal phantom was fabricated from polyvinyl chloride plastisol and phantom motion was simulated with a programmable motion stage and plunger. A deformable normoxic polyacrylamide gel (nPAG) dosimeter was incorporated into the phantom apparatus to represent a liver tumor. Dosimeter data were acquired using magnetic resonance imaging (MRI). Static measurements were compared to planned dose distributions. Static and dynamic deformations were used to simulate inter- and intrafractional motion in the phantom and measurements were compared to baseline measurements. RESULTS The statically irradiated dosimeters matched the planned dose distribution with an average γ pass rates of 97.0 ± 0.5% and 97.5 ± 0.2% for 3%/5 mm and 5%/5 mm criteria, respectively. Static deformations caused measured dose distribution shifts toward the phantom plunger. During the dynamic deformation experiment, the dosimeter that utilized beam gating showed an improvement in the γ pass rate compared to the dosimeter that did not. CONCLUSIONS A deformable abdominal phantom apparatus which incorporates a deformable nPAG dosimeter was developed to test real-time IGRT systems and deformable dose accumulation algorithms. This apparatus was used to benchmark simple static irradiations in which it was found that measurements match well to the planned distributions. Deformable dose accumulation could be tested by directly measuring the shifts and blurring of the target dose due to interfractional organ deformation and motion. Dosimetric improvements were achieved from the motion management during intrafractional motion.
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Affiliation(s)
- Charles K. Matrosic
- School of Medicine and Public Health, Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Jennifer Hull
- School of Medicine and Public Health, Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Benjamin Palmer
- School of Medicine and Public Health, Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Wesley Culberson
- School of Medicine and Public Health, Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
| | - Bryan Bednarz
- School of Medicine and Public Health, Department of Medical PhysicsUniversity of Wisconsin‐MadisonMadisonWisconsinUSA
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Kadoya N, Kito S, Kurooka M, Saito M, Takemura A, Tohyama N, Tominaga M, Nakajima Y, Fujita Y, Miyabe Y. Factual survey of the clinical use of deformable image registration software for radiotherapy in Japan. JOURNAL OF RADIATION RESEARCH 2019; 60:546-553. [PMID: 31125076 PMCID: PMC6640912 DOI: 10.1093/jrr/rrz034] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 02/24/2019] [Indexed: 05/02/2023]
Abstract
Deformable image registration (DIR) has recently become commercially available in the field of radiotherapy. However, there was no detailed information regarding the use of DIR software at each medical institution. Thus, in this study, we surveyed the status of the clinical use of DIR software for radiotherapy in Japan. The Japan Society of Medical Physics and the Japanese Society for Radiation Oncology mailing lists were used to announce this survey. The questionnaire was created by investigators working under the research grant of the Japanese Society for Radiation Oncology (2017-2018) and intended for the collection of information regarding the use of DIR in radiotherapy. The survey was completed by 161 institutions in Japan. The survey results showed that dose accumulation was the most frequent purpose for which DIR was used in clinical practice (73%). Various commissioning methods were performed, although they were not standardized. Qualitative evaluation with actual patient images was the most commonly used method (28%), although 30% of the total number of responses (42% of institutions) reported that they do not perform commissioning. We surveyed the current status of clinical use of DIR software for radiotherapy in Japan for the first time. Our results indicated that a certain number of institutions used DIR software for clinical practice, and various commissioning methods were performed, although they were not standardized. Taken together, these findings highlight the need for a technically unified approach for commissioning and quality assurance for the use of DIR software in Japan.
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Affiliation(s)
- Noriyuki Kadoya
- Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
- Corresponding author. Department of Radiation Oncology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, 980-8574 Japan. Tel: +81-22-717-7312; Fax: +81-22-717-7316; E-mail:
| | - Satoshi Kito
- Department of Radiotherapy, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
| | | | - Masahide Saito
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Akihiro Takemura
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Naoki Tohyama
- Department of Radiation Oncology, Tokyo Bay Advanced Imaging and Radiation Oncology Clinic Makuhari, Chiba, Japan
| | - Masahide Tominaga
- Department of Therapeutic Radiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima, Japan
| | - Yujiro Nakajima
- Department of Radiotherapy, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
| | - Yukio Fujita
- Department of Radiological Sciences, Faculty of Health Sciences, Komazawa University, Tokyo, Japan
| | - Yuki Miyabe
- Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, Kyoto, Japan
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20
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He Y, Qin S, Dyer BA, Zhang H, Zhao L, Chen T, Zheng F, Sun Y, Shi L, Rong Y, Qiu J. Characterizing mechanical and medical imaging properties of polyvinyl chloride-based tissue-mimicking materials. J Appl Clin Med Phys 2019; 20:176-183. [PMID: 31207035 PMCID: PMC6612694 DOI: 10.1002/acm2.12661] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 04/25/2019] [Accepted: 05/23/2019] [Indexed: 01/09/2023] Open
Abstract
Polyvinyl chloride (PVC) is a commonly used tissue‐mimicking material (TMM) for phantom construction using 3D printing technology. PVC‐based TMMs consist of a mixture of PVC powder and dioctyl terephthalate as a softener. In order to allow the clinical use of a PVC‐based phantom use across CT and magnetic resonance imaging (MRI) imaging platforms, we evaluated the mechanical and physical imaging characteristics of ten PVC samples. The samples were made with different PVC‐softener ratios to optimize phantom bioequivalence with physiologic human tissue. Phantom imaging characteristics, including computed tomography (CT) number, MRI relaxation time, and mechanical properties (e.g., Poisson’s ratio and elastic modulus) were quantified. CT number varied over a range of approximately −10 to 110 HU. The relaxation times of the T1‐weighted and T2‐weighted images were 206.81 ± 17.50 and 20.22 ± 5.74 ms, respectively. Tensile testing was performed to evaluate mechanical properties on the three PVC samples that were closest to human tissue. The elastic moduli for these samples ranged 7.000–12.376 MPa, and Poisson’s ratios were 0.604–0.644. After physical and imaging characterization of the various PVC‐based phantoms, we successfully produced a bioequivalent phantom compatible with multimodal imaging platforms for machine calibration and image optimization/benchmarking. By combining PVC with 3D printing technologies, it is possible to construct imaging phantoms simulating human anatomies with tissue equivalency.
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Affiliation(s)
- Yaoyao He
- Medical engineering and technology center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Imaging-X Joint laboratory, Taian, China.,Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Shengxue Qin
- College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, China
| | - Brandon A Dyer
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, CA, USA
| | - Hongbin Zhang
- College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao, China
| | - Lifen Zhao
- School of Material Science and Engineering, Shandong University of Science and Technology, Qingdao, China
| | - Tiao Chen
- Medical engineering and technology center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Imaging-X Joint laboratory, Taian, China.,Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Department of Radiology, Hubei Cancer Hospital, Wuhan, China
| | - Fenglian Zheng
- Medical engineering and technology center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Imaging-X Joint laboratory, Taian, China.,Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Yong Sun
- Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Liting Shi
- Medical engineering and technology center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Imaging-X Joint laboratory, Taian, China.,Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
| | - Yi Rong
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, CA, USA
| | - Jianfeng Qiu
- Medical engineering and technology center, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China.,Imaging-X Joint laboratory, Taian, China.,Radiology Department, Shandong First Medical University & Shandong Academy of Medical Sciences, Taian, China
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Ehrbar S, Jöhl A, Kühni M, Meboldt M, Ozkan Elsen E, Tanner C, Goksel O, Klöck S, Unkelbach J, Guckenberger M, Tanadini-Lang S. ELPHA: Dynamically deformable liver phantom for real-time motion-adaptive radiotherapy treatments. Med Phys 2019; 46:839-850. [PMID: 30588635 DOI: 10.1002/mp.13359] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 12/03/2018] [Accepted: 12/14/2018] [Indexed: 12/25/2022] Open
Abstract
PURPOSE Real-time motion-adaptive radiotherapy of intrahepatic tumors needs to account for motion and deformations of the liver and the target location within. Phantoms representative of anatomical deformations are required to investigate and improve dynamic treatments. A deformable phantom capable of testing motion detection and motion mitigation techniques is presented here. METHODS The dynamically dEformable Liver PHAntom (ELPHA) was designed to fulfill three main constraints: First, a reproducibly deformable anatomy is required. Second, the phantom should provide multimodality imaging contrast for motion detection. Third, a time-resolved dosimetry system to measure temporal effects should be provided. An artificial liver with vasculature was casted from soft silicone mixtures. The silicones allow for deformation and radiographic image contrast, while added cellulose provides ultrasonic contrast. An actuator was used for compressing the liver in the inferior direction according to a prescribed respiratory motion trace. Electromagnetic (EM) transponders integrated in ELPHA help provide ground truth motion traces. They were used to quantify the motion reproducibility of the phantom and to validate motion detection based on ultrasound imaging. A two-dimensional ultrasound probe was used to follow the position of the vessels with a template-matching algorithm. This detected vessel motion was compared to the EM transponder signal by calculating the root-mean-square error (RMSE). ELPHA was then used to investigate the dose deposition of dynamic treatment deliveries. Two dosimetry systems, radio-chromic film and plastic scintillation dosimeters (PSD), were integrated in ELPHA. The PSD allow for time-resolved measurement of the delivered dose, which was compared to a time-resolved dose of the treatment planning system. Film and PSD were used to investigate dose delivery to the deforming phantom without motion compensation and with treatment-couch tracking for motion compensation. RESULTS ELPHA showed densities of 66 and 45 HU in the liver and the surrounding tissues. A high motion reproducibility with a submillimeter RMSE (<0.32 mm) was measured. The motion of the vasculature detected with ultrasound agreed well with the EM transponder position (RMSE < 1 mm). A time-resolved dosimetry system with a 1 Hz time resolution was achieved with the PSD. The agreement of the planned and measured dose to the PSD decreased with increasing motion amplitude: A dosimetric RMSE of 1.2, 2.1, and 2.7 cGy/s was measured for motion amplitudes of 8, 16, and 24 mm, respectively. With couch tracking as motion compensation, these values decreased to 1.1, 1.4, and 1.4 cGy/s. This is closer to the static situation with 0.7 cGy/s. Film measurements showed that couch tracking was able to compensate for motion with a mean target dose within 5% of the static situation (-5% to +1%), which was higher than in the uncompensated cases (-41% to -1%). CONCLUSIONS ELPHA is a deformable liver phantom with high motion reproducibility. It was demonstrated to be suitable for the verification of motion detection and motion mitigation modalities. Based on the multimodality image contrast, a high accuracy of ultrasound based motion detection was shown. With the time-resolved dosimetry system, ELPHA is suitable for performance assessment of real-time motion-adaptive radiotherapy, as was shown exemplary with couch tracking.
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Affiliation(s)
- Stefanie Ehrbar
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland
| | - Alexander Jöhl
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland.,Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, 8001, Zurich, Switzerland
| | - Michael Kühni
- Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, 8001, Zurich, Switzerland
| | - Mirko Meboldt
- Department of Mechanical and Process Engineering, Product Development Group Zurich, ETH Zurich, 8001, Zurich, Switzerland
| | - Ece Ozkan Elsen
- Department of Information Technology and Electrical Engineering, Computer-assisted Applications in Medicine, ETH Zurich, 8001, Zürich, Switzerland
| | - Christine Tanner
- Department of Information Technology and Electrical Engineering, Computer-assisted Applications in Medicine, ETH Zurich, 8001, Zürich, Switzerland
| | - Orcun Goksel
- Department of Information Technology and Electrical Engineering, Computer-assisted Applications in Medicine, ETH Zurich, 8001, Zürich, Switzerland
| | - Stephan Klöck
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland
| | - Jan Unkelbach
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland
| | - Matthias Guckenberger
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland
| | - Stephanie Tanadini-Lang
- Department of Radiation Oncology, University Hospital Zurich and, University of Zurich, 8091, Zurich, Switzerland
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He Y, Liu Y, Dyer BA, Boone JM, Liu S, Chen T, Zheng F, Zhu Y, Sun Y, Rong Y, Qiu J. 3D-printed breast phantom for multi-purpose and multi-modality imaging. Quant Imaging Med Surg 2019; 9:63-74. [PMID: 30788247 DOI: 10.21037/qims.2019.01.05] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Background Breast imaging technology plays an important role in breast cancer planning and treatment. Recently, three-dimensional (3D) printing technology has become a trending issue in phantom constructions for medical applications, with its advantages of being customizable and cost-efficient. However, there is no current practice in the field of multi-purpose breast phantom for quality control (QC) in multi-modalities imaging. The purpose of this study was to fabricate a multi-purpose breast phantom with tissue-equivalent materials via a 3D printing technique for QC in multi-modalities imaging. Methods We used polyvinyl chloride (PVC) based materials and a 3D printing technique to construct a breast phantom. The phantom incorporates structures imaged in the female breast such as microcalcifications, fiber lesions, and tumors with different sizes. Moreover, the phantom was used to assess the sensitivity of lesion detection, depth resolution, and detectability thresholds with different imaging modalities. Phantom tissue equivalent properties were determined using computed tomography (CT) attenuation [Hounsfield unit (HU)] and magnetic resonance imaging (MRI) relaxation times. Results The 3D-printed breast phantom had an average background value of 36.2 HU, which is close to that of glandular breast tissue (40 HU). T1 and T2 relaxation times had an average relaxation time of 206.81±17.50 and 20.22±5.74 ms, respectively. Mammographic imaging had improved detection of microcalcification compared with ultrasound and MRI with multiple sequences [T1WI, T2WI and short inversion time inversion recovery (STIR)]. Soft-tissue lesion detection and cylindrical tumor contrast were superior with mammography and MRI compared to ultrasound. Hemispherical tumor detection was similar regardless of the imaging modality used. Conclusions We developed a multi-purpose breast phantom using a 3D printing technique and determined its value for multi-modal breast imaging studies.
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Affiliation(s)
- Yaoyao He
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China
| | - Yulin Liu
- Department of Radiology, Hubei Cancer Hospital, Wuhan 430079, China
| | - Brandon A Dyer
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, CA 95630, USA
| | - John M Boone
- Department of Radiology, University of California Davis Medical Center, Sacramento, California 95817, USA
| | - Shanshan Liu
- Department of Radiology, Affiliated Hospital of Taishan Medical University, Taian 271016, China
| | - Tiao Chen
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China.,Department of Radiology, Hubei Cancer Hospital, Wuhan 430079, China
| | - Fenglian Zheng
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China
| | - Ye Zhu
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China
| | - Yong Sun
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China
| | - Yi Rong
- Department of Radiation Oncology, University of California Davis Medical Center, Sacramento, CA 95630, USA
| | - Jianfeng Qiu
- Medical Engineering and Technology Center, Taishan Medical University, Taian 271016, China
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Wang C, Liao Y, Chen H, Zhen X, Li J, Xu Y, Zhou L. Influence of tube potential on quantitative coronary plaque analyses by low radiation dose computed tomography: a phantom study. Int J Cardiovasc Imaging 2018; 34:1315-1322. [PMID: 29582238 DOI: 10.1007/s10554-018-1344-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 03/22/2018] [Indexed: 12/18/2022]
Abstract
Previous studies have shown that employing the low dose computed tomography (CT) technique based on low tube potential reduces the radiation dose required for the coronary artery examination protocol. However, low tube potential may adversely influence the CT number of plaque composition. Therefore, we aimed to determine whether quantitative atherosclerotic plaque analysis by a multi-slice, low radiation dose CT protocol using 80 kilovolts (kV) yields results comparable to those of the standard 120 kV protocol. Artificial plaque samples (n = 17) composed of three kinds of plaque were scanned at 120 and 80 kV. Relative low-density and medium-density plaque component volumes obtained by three protocols (80 kV, 60 Hounsfield units [HU] threshold; 120 kV, 60 HU threshold; and 80 kV, 82 HU threshold) were compared. Using the 60 HU threshold, relative volume of the low-density plaque component obtained at 80 kV was lower than that obtained at 120 kV (27 ± 3% vs. 51 ± 5%, P < 0.001), whereas relative volume of the medium-density plaque component obtained at 80 kV was higher than that obtained at 120 kV (73 ± 3% vs. 48 ± 5%, P < 0.001). By contrast, no significant difference in relative volume obtained at 80 kV (82 HU threshold) versus 120 kV (60 HU threshold) was observed for either low-density (52 ± 5% vs. 51 ± 5%) or medium-density (48 ± 5% vs. 48 ± 5%) plaque component. Low tube potential may affect the accuracy of quantitative atherosclerotic plaque analysis. For our phantom test, 82 HU was the optimal threshold for scanning at 80 kV.
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Affiliation(s)
- Chunhong Wang
- Department of Radiology, Xinyang Central Hospital, Xinyang, 464002, Henan, China
| | - Yuliang Liao
- Department of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Haibin Chen
- Department of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Xin Zhen
- Department of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, Guangdong, China
| | - Jianhong Li
- Department of Radiology, Xinyang Central Hospital, Xinyang, 464002, Henan, China
| | - Yikai Xu
- Department of Medical Imaging Center, Nanfang Hospital, Southern Medical University, No. 1838 Guangzhou Avenue North, Guangzhou, 510515, Guangdong, China.
| | - Linghong Zhou
- Department of Biomedical Engineering, Southern Medical University, Guangzhou, 510515, Guangdong, China.
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