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Chien CL, Zhao X, Guo B, Zhang R. Technical note: Preprocessing of portal images to improve image quality of VMAT-CT. Med Phys 2024; 51:2119-2127. [PMID: 37727132 DOI: 10.1002/mp.16741] [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: 01/31/2023] [Revised: 08/28/2023] [Accepted: 08/28/2023] [Indexed: 09/21/2023] Open
Abstract
BACKGROUND The concept of volumetric modulated arc therapy-computed tomography (VMAT-CT) was proposed more than a decade ago. However, its application has been very limited mainly due to the poor image quality. More specifically, the blurred areas in electronic portal imaging device (EPID) images collected during VMAT heavily degrade the image quality of VMAT-CT. PURPOSE The goal of this study was to propose systematic methods to preprocess EPID images and improve the image quality of VMAT-CT. METHODS Online region-based active contour method was introduced to binarize portal images. Multi-leaf collimator (MLC) motion modeling was developed to remove the MLC motion blur. Outlier filtering was then applied to replace the remaining artifacts with plausible data. To assess the impact of these preprocessing methods on the image quality of VMAT-CT, 44 clinical VMAT plans for several treatment sites (lung, esophagus, and head & neck) were delivered to a Rando phantom, and several real-patient cases were also acquired. VMAT-CT reconstruction was attempted for all the cases, and image quality was evaluated. RESULTS All three preprocessing methods could effectively remove the blurred edges of EPID images. The combined preprocessing methods not only saved VMAT-CT from distortions and artifacts, but also increased the percentage of VMAT plans that can be reconstructed. CONCLUSIONS The systematic preprocessing of portal images improves the image quality of VMAT-CT significantly, and facilitates the application of VMAT-CT as an effective image guidance tool.
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Affiliation(s)
- Chia-Lung Chien
- Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Xiaodong Zhao
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Beibei Guo
- Department of Experimental Statistics, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Rui Zhang
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana, USA
- Department of Radiation Oncology, Mary Bird Perkins Cancer Center, Baton Rouge, Louisiana, USA
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Østergaard DE, Bryce-Atkinson A, Skaarup M, Smulders B, Davies LSC, Whitfield G, Janssens GO, Hjalgrim LL, Richter IV, van Herk M, Aznar M, Vestmø Maraldo M. Paediatric CBCT protocols for image-guided radiotherapy; outcome of a survey across SIOP Europe affiliated countries and literature review. Radiother Oncol 2024; 190:109963. [PMID: 38406888 DOI: 10.1016/j.radonc.2023.109963] [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: 06/01/2023] [Revised: 10/17/2023] [Accepted: 10/20/2023] [Indexed: 02/27/2024]
Abstract
BACKGROUND Implementation of daily cone-beam CT (CBCT) into clinical practice in paediatric image-guided radiotherapy (IGRT) lags behind compared to adults. Surveys report wide variation in practice for paediatric IGRT and technical information remains unreported. In this study we report on technical settings from applied paediatric CBCT protocols and review the literature for paediatric CBCT protocols. METHODS From September to October 2022, a survey was conducted among 246 SIOPE-affiliated centres across 35 countries. The survey consisted of 3 parts: 1) baseline information; technical CBCT exposure settings and patient set-up procedure for 2) brain/head, and 3) abdomen. Descriptive statistics was used to summarise current practice. The literature was reviewed systematically with two reviewers obtaining consensus RESULTS: The literature search revealed 22 papers concerning paediatric CBCT protocols. Seven papers focused on dose-optimisation. Responses from 50/246 centres in 25/35 countries were collected: 44/50 treated with photons and 10/50 with protons. In total, 48 brain/head and 53 abdominal protocols were reported. 42/50 centres used kV-CBCT for brain/head and 35/50 for abdomen; daily CBCT was used for brain/head = 28/48 (58%) and abdomen = 33/53 62%. Greater consistency was seen in brain/head protocols (dose range 0.32 - 67.7 mGy) compared to abdominal (dose range 0.27 - 119.7 mGy). CONCLUSION Although daily CBCT is now widely used in paediatric IGRT, our survey demonstrates a wide range of technical settings, suggesting an unmet need to optimise paediatric IGRT protocols. This is in accordance with the literature. However, there are only few paediatric optimisation studies suggesting that dose reduction is possible while maintaining image quality.
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Affiliation(s)
- Daniella Elisabet Østergaard
- Section of Radiotherapy, Department of Oncology, Centre for Cancer and Organ Diseases, Copenhagen University Hospital, Copenhagen, Denmark; Faculty of Health and Medical Sciences, Copenhagen University, Copenhagen, Denmark.
| | - Abigail Bryce-Atkinson
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Mikkel Skaarup
- Section of Radiotherapy, Department of Oncology, Centre for Cancer and Organ Diseases, Copenhagen University Hospital, Copenhagen, Denmark
| | - Bob Smulders
- Section of Radiotherapy, Department of Oncology, Centre for Cancer and Organ Diseases, Copenhagen University Hospital, Copenhagen, Denmark; Danish Centre for Particle Therapy, Aarhus University Hospital, Aarhus, Denmark
| | | | - Gillian Whitfield
- Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, UK; The Children's Brain Tumour Research Network, The University of Manchester, Royal Manchester Children's Hospital, Manchester, UK
| | - Geert O Janssens
- Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, the Netherlands; Princess Máxima Center for Pediatric Oncology, Utrecht, the Netherlands
| | - Lisa Lyngsie Hjalgrim
- Department of Paediatrics and Adolescent Medicine, Copenhagen University Hospital, Copenhagen, Denmark
| | - Ivan Vogelius Richter
- Section of Radiotherapy, Department of Oncology, Centre for Cancer and Organ Diseases, Copenhagen University Hospital, Copenhagen, Denmark; Faculty of Health and Medical Sciences, Copenhagen University, Copenhagen, Denmark
| | - Marcel van Herk
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Marianne Aznar
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
| | - Maja Vestmø Maraldo
- Section of Radiotherapy, Department of Oncology, Centre for Cancer and Organ Diseases, Copenhagen University Hospital, Copenhagen, Denmark
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Becksfort J, Uh J, Saunders A, Byrd JA, Worrall HM, Marker M, Melendez-Suchi C, Li Y, Chang J, Raghavan K, Merchant TE, Hua CH. Setup Uncertainty of Pediatric Brain Tumor Patients Receiving Proton Therapy: A Prospective Study. Cancers (Basel) 2023; 15:5486. [PMID: 38001746 PMCID: PMC10670653 DOI: 10.3390/cancers15225486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 11/11/2023] [Accepted: 11/13/2023] [Indexed: 11/26/2023] Open
Abstract
This study quantifies setup uncertainty in brain tumor patients who received image-guided proton therapy. Patients analyzed include 165 children, adolescents, and young adults (median age at radiotherapy: 9 years (range: 10 months to 24 years); 80 anesthetized and 85 awake) enrolled in a single-institution prospective study from 2020 to 2023. Cone-beam computed tomography (CBCT) was performed daily to calculate and correct manual setup errors, once per course after setup correction to measure residual errors, and weekly after treatments to assess intrafractional motion. Orthogonal radiographs were acquired consecutively with CBCT for paired comparisons of 40 patients. Translational and rotational errors were converted from 6 degrees of freedom to a scalar by a statistical approach that considers the distance from the target to the isocenter. The 95th percentile of setup uncertainty was reduced by daily CBCT from 10 mm (manual positioning) to 1-1.5 mm (after correction) and increased to 2 mm by the end of fractional treatment. A larger variation existed between the roll corrections reported by radiographs vs. CBCT than for pitch and yaw, while there was no statistically significant difference in translational variation. A quantile mixed regression model showed that the 95th percentile of intrafractional motion was 0.40 mm lower for anesthetized patients (p=0.0016). Considering additional uncertainty in radiation-imaging isocentricity, the commonly used total plan robustness of 3 mm against positional uncertainty would be appropriate for our study cohort.
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Affiliation(s)
- Jared Becksfort
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Jinsoo Uh
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Andrew Saunders
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Julia A. Byrd
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Hannah M. Worrall
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Matt Marker
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Christian Melendez-Suchi
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Yimei Li
- Department of Biostatistics, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA
| | - Jenghwa Chang
- Department of Radiation Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549, USA
| | - Kavitha Raghavan
- Department of Pediatric Medicine, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA;
| | - Thomas E. Merchant
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
| | - Chia-ho Hua
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, TN 38105, USA; (J.U.); (J.A.B.); (H.M.W.); (T.E.M.); (C.-h.H.)
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Wang T, Liu X, Dai J, Zhang C, He W, Liu L, Chan Y, He Y, Zhao H, Xie Y, Liang X. An unsupervised dual contrastive learning framework for scatter correction in cone-beam CT image. Comput Biol Med 2023; 165:107377. [PMID: 37651766 DOI: 10.1016/j.compbiomed.2023.107377] [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: 04/02/2023] [Revised: 08/08/2023] [Accepted: 08/14/2023] [Indexed: 09/02/2023]
Abstract
PURPOSE Cone-beam computed tomography (CBCT) is widely utilized in modern radiotherapy; however, CBCT images exhibit increased scatter artifacts compared to planning CT (pCT), compromising image quality and limiting further applications. Scatter correction is thus crucial for improving CBCT image quality. METHODS In this study, we proposed an unsupervised contrastive learning method for CBCT scatter correction. Initially, we transformed low-quality CBCT into high-quality synthetic pCT (spCT) and generated forward projections of CBCT and spCT. By computing the difference between these projections, we obtained a residual image containing image details and scatter artifacts. Image details primarily comprise high-frequency signals, while scatter artifacts consist mainly of low-frequency signals. We extracted the scatter projection signal by applying a low-pass filter to remove image details. The corrected CBCT (cCBCT) projection signal was obtained by subtracting the scatter artifacts projection signal from the original CBCT projection. Finally, we employed the FDK reconstruction algorithm to generate the cCBCT image. RESULTS To evaluate cCBCT image quality, we aligned the CBCT and pCT of six patients. In comparison to CBCT, cCBCT maintains anatomical consistency and significantly enhances CT number, spatial homogeneity, and artifact suppression. The mean absolute error (MAE) of the test data decreased from 88.0623 ± 26.6700 HU to 17.5086 ± 3.1785 HU. The MAE of fat regions of interest (ROIs) declined from 370.2980 ± 64.9730 HU to 8.5149 ± 1.8265 HU, and the error between their maximum and minimum CT numbers decreased from 572.7528 HU to 132.4648 HU. The MAE of muscle ROIs reduced from 354.7689 ± 25.0139 HU to 16.4475 ± 3.6812 HU. We also compared our proposed method with several conventional unsupervised synthetic image generation techniques, demonstrating superior performance. CONCLUSIONS Our approach effectively enhances CBCT image quality and shows promising potential for future clinical adoption.
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Affiliation(s)
- Tangsheng Wang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China; University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Xuan Liu
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Jingjing Dai
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Chulong Zhang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Wenfeng He
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Lin Liu
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China; University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Yinping Chan
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Yutong He
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Hanqing Zhao
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China; University of Chinese Academy of Sciences, Beijing 101408, China.
| | - Yaoqin Xie
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
| | - Xiaokun Liang
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China.
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Popotte C, Letellier R, Paul D, Waltener A, Guillochon N, Munier M, Retif P. Evaluation of a Scintillating Plastic Optical Fiber Device for Measuring kV-Cone Beam Computed Tomography Dose. SENSORS (BASEL, SWITZERLAND) 2023; 23:7778. [PMID: 37765835 PMCID: PMC10536616 DOI: 10.3390/s23187778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/01/2023] [Accepted: 09/07/2023] [Indexed: 09/29/2023]
Abstract
BACKGROUND Justification of imaging procedures such as cone beam computed tomography (CBCT) in radiotherapy makes no doubt. However, the CBCT composite dose is rarely reported or optimized, even though the repeated CBCT cumulative dose can be up to 3% of the prescription dose. This study aimed to evaluate the performance and utility of a new plastic scintillating optical fiber dosimeter for CBCT dosimetric quality assurance (QA) applications before a potential application in patient composite CBCT dosimetry. METHODS The dosimeter, made of 1 mm diameter plastic fiber, was installed under a linear accelerator treatment table and linked to photodetectors. The fiber impact on the fluence and dose delivered was respectively assessed with an electronic portal imaging device (EPID) and EBT3 Gafchromic® film. The presence of artifacts was visually evaluated on kV images. The dosimeter performances were determined for various acquisition parameters by comparison with ionization chamber values. RESULTS The maximum impact of the fiber on the fluence measured by the EPID was -1.2% for the 6 MV flattening filter-free beam. However, the fiber did not alter the film dose profile when measured for all the beams tested. The fiber was not visible at energies ≥ 80 kV and was merely visible on the CBCT images. When the rate of images per second or mA was changed, the maximum relative difference between the device and the ionization chamber CTDIs was <5%. Changing collimation led to a -7.2% maximum relative difference with an absolute dose difference that was insignificant (-0.3 mGy). Changing kV was associated with a -8.7% maximum relative difference, as published in the literature. CONCLUSIONS The dosimeter may be a promising device for CBCT recurrent dosimetry quality control or dose optimization. According to these results, further developments are in progress in order to adapt the solution to the measurement of patient composite CBCT doses.
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Affiliation(s)
- Christian Popotte
- INSERM Unité U1296 Radiations: Défense, Santé Environnement, 69008 Lyon, France
- Fibermetrix, 7 Allée de l’Europe, 67960 Entzheim, France
| | | | - Didier Paul
- INSERM Unité U1296 Radiations: Défense, Santé Environnement, 69008 Lyon, France
| | | | | | - Mélodie Munier
- INSERM Unité U1296 Radiations: Défense, Santé Environnement, 69008 Lyon, France
- Fibermetrix, 7 Allée de l’Europe, 67960 Entzheim, France
| | - Paul Retif
- Medical Physics Unit, CHR Metz-Thionville, 57000 Metz, France
- Centre National de la Recherche Scientifique, Centre de Recherche en Automatique de Nancy, Université de Lorraine, 54000 Nancy, France
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6
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Taylor S, Lim P, Cantwell J, D’Souza D, Moinuddin S, Chang YC, Gaze MN, Gains J, Veiga C. Image guidance and interfractional anatomical variation in paediatric abdominal radiotherapy. Br J Radiol 2023; 96:20230058. [PMID: 37102707 PMCID: PMC10230397 DOI: 10.1259/bjr.20230058] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 04/28/2023] Open
Abstract
OBJECTIVES To identify variables predicting interfractional anatomical variations measured with cone-beam CT (CBCT) throughout abdominal paediatric radiotherapy, and to assess the potential of surface-guided radiotherapy (SGRT) to monitor these changes. METHODS Metrics of variation in gastrointestinal (GI) gas volume and separation of the body contour and abdominal wall were calculated from 21 planning CTs and 77 weekly CBCTs for 21 abdominal neuroblastoma patients (median 4 years, range: 2 - 19 years). Age, sex, feeding tubes, and general anaesthesia (GA) were explored as predictive variables for anatomical variation. Furthermore, GI gas variation was correlated with changes in body and abdominal wall separation, as well as simulated SGRT metrics of translational and rotational corrections between CT/CBCT. RESULTS GI gas volumes varied 74 ± 54 ml across all scans, while body and abdominal wall separation varied 2.0 ± 0.7 mm and 4.1 ± 1.5 mm from planning, respectively. Patients < 3.5 years (p = 0.04) and treated under GA (p < 0.01) experienced greater GI gas variation; GA was the strongest predictor in multivariate analysis (p < 0.01). Absence of feeding tubes was linked to greater body contour variation (p = 0.03). GI gas variation correlated with body (R = 0.53) and abdominal wall (R = 0.63) changes. The strongest correlations with SGRT metrics were found for anterior-posterior translation (R = 0.65) and rotation of the left-right axis (R = -0.36). CONCLUSIONS Young age, GA, and absence of feeding tubes were linked to stronger interfractional anatomical variation and are likely indicative of patients benefiting from adaptive/robust planning pathways. Our data suggest a role for SGRT to inform the need for CBCT at each treatment fraction in this patient group. ADVANCES IN KNOWLEDGE This is the first study to suggest the potential role of SGRT for the management of internal interfractional anatomical variation in paediatric abdominal radiotherapy.
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Affiliation(s)
- Sabrina Taylor
- University College London, Centre for Medical Image Computing, London, United Kingdom
| | - Pei Lim
- Department of Oncology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Jessica Cantwell
- Radiotherapy, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Derek D’Souza
- Radiotherapy, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Syed Moinuddin
- Radiotherapy, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Yen-Ching Chang
- Department of Oncology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Mark N Gaze
- Department of Oncology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Jennifer Gains
- Department of Oncology, University College London Hospitals NHS Foundation Trust, London, United Kingdom
| | - Catarina Veiga
- University College London, Centre for Medical Image Computing, London, United Kingdom
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Wong YM, Koh CWY, Lew KS, Chua CGA, Nei W, Tan HQ, Lee JCL, Mazonakis M, Damilakis J. A review on fetal dose in Radiotherapy: A historical to contemporary perspective. Phys Med 2023; 105:102513. [PMID: 36565555 DOI: 10.1016/j.ejmp.2022.102513] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/09/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
This paper aims to review on fetal dose in radiotherapy and extends and updates on a previous work1 to include proton therapy. Out-of-field doses, which are the doses received by regions outside of the treatment field, are unavoidable regardless of the treatment modalities used during radiotherapy. In the case of pregnant patients, fetal dose is a major concern as it has long been recognized that fetuses exposed to radiation have a higher probability of suffering from adverse effects such as anatomical malformations and even fetal death, especially when the 0.1Gy threshold is exceeded. In spite of the low occurrence of cancer during pregnancy, the radiotherapy team should be equipped with the necessary knowledge to deal with fetal dose. This is crucial so as to ensure that the fetus is adequately protected while not compromising the patient treatment outcomes. In this review paper, various aspects of fetal dose will be discussed ranging from biological, clinical to the physics aspects. Other than fetal dose resulting from conventional photon therapy, this paper will also extend the discussion to modern treatment modalities and techniques, namely proton therapy and image-guided radiotherapy, all of which have seen a significant increase in use in current radiotherapy. This review is expected to provide readers with a comprehensive understanding of fetal dose in radiotherapy, and to be fully aware of the steps to be taken in providing radiotherapy for pregnant patients.
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Affiliation(s)
- Yun Ming Wong
- Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | | | - Kah Seng Lew
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | | | - Wenlong Nei
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore
| | - Hong Qi Tan
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore.
| | - James Cheow Lei Lee
- Division of Radiation Oncology, National Cancer Centre Singapore, Singapore; Division of Physics and Applied Physics, Nanyang Technological University, Singapore
| | - Michael Mazonakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
| | - John Damilakis
- Department of Medical Physics, School of Medicine, University of Crete, Greece
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Zhao X, Zhang R. Feasibility of 4D VMAT-CT. Biomed Phys Eng Express 2022; 8:10.1088/2057-1976/ac9848. [PMID: 36206726 PMCID: PMC9629170 DOI: 10.1088/2057-1976/ac9848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/07/2022] [Indexed: 11/11/2022]
Abstract
Objective.Feasibility of three-dimensional (3D) tracking of volumetric modulated arc therapy (VMAT) based on VMAT-computed tomography (VMAT-CT) has been shown previously by our group. However, 3D VMAT-CT is not suitable for treatments that involve significant target movement due to patient breathing. The goal of this study was to reconstruct four-dimensional (4D) VMAT-CT and evaluate the feasibility of tracking based on 4D VMAT-CT.Approach.Synchronized portal images of phantoms and linac log were both sorted into four phases, and VMAT-CT+ was generated in each phase by fusing reconstructed VMAT-CT and planning CT using rigid or deformable registration. Dose was calculated in each phase and was registered to the mean position planning CT for 4D dose reconstruction. Trackings based on 4D VMAT-CT+ and 4D cone beam CT (CBCT) were compared. Potential uncertainties were also evaluated.Main results.Tracking based on 4D VMAT-CT+ was accurate, could detect phantom deformation and/or change of breathing pattern, and was superior to that based on 4D CBCT. The impact of uncertainties on tracking was minimal.Significance.Our study shows it is feasible to accurately track position and dose based on 4D VMAT-CT for patients whose VMAT treatments are subject to respiratory motion. It will significantly increase the confidence of VMAT and is a clinically viable solution to daily patient positioning,in vivodosimetry and treatment monitoring.
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Affiliation(s)
- Xiaodong Zhao
- Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Rui Zhang
- Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA, USA
- Department of Radiation Oncology, Mary Bird Perkins Cancer Center, Baton Rouge, LA, USA
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Al-Kabkabi A, Ramachandran P, Aamry A, Tamam N, Abuhadi NH, Johary Y, Aamri H, Sulieman A, Trapp J. Assessment of cone beam computed tomography image quality and dose for commonly used pre-sets in external beam radiotherapy. Radiat Phys Chem Oxf Engl 1993 2022. [DOI: 10.1016/j.radphyschem.2022.110287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Huang Y, Hu X, Zhong Y, Lai Y, Shen C, Jia X. Improving dose calculation accuracy in preclinical radiation experiments using multi-energy element resolved cone beam CT. Phys Med Biol 2021; 66. [PMID: 34753117 DOI: 10.1088/1361-6560/ac37fc] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 11/09/2021] [Indexed: 11/12/2022]
Abstract
Cone-beam CT (CBCT) in modern pre-clinical small-animal radiation research platforms provides volumetric images for image guidance and experiment planning purposes. In this work, we implemented multi-energy element-resolved (MEER) CBCT using three scans with different kVps on a SmART platform (Precision X-ray Inc.) We performed comprehensive calibration tasks achieve sufficient accuracy for this quantitative imaging purpose. For geometry calibration, we scanned a ball bearing phantom and used an analytical method together with an optimization approach to derive gantry-angle specific geometry parameters. Intensity calibration and correction included the corrections for detector lag, glare, and beam hardening. The corrected CBCT projection images acquired at 30, 40 and 60 kVp in multiple scans were used to reconstruct CBCT images using the Feldkamp-Davis-Kress reconstruction algorithm. After that, an optimization problem was solved to determine images of relative electron density (rED) and elemental composition (EC) that are needed for Monte Carlo-based radiation dose calculation. We demonstrated effectiveness of our CBCT calibration steps by showing improvements in image quality and successful material decomposition in cases with a small animal CT calibration phantom and a plastinated mouse phantom. It was found that artifacts induced by geometry inaccuracy, detector lag, glare and beam hardening were visually reduced. CT number mean errors were reduced from 19\% to 5\%. In the CT calibration phantom case, median errors in H, O, and Ca fractions for all the inserts were below 1\%, 2\%, and 4\% respectively, and median error in rED was less than 5\%. Compared to standard approach deriving material type and rED via CT number conversion, our approach improved Monte Carlo simulation-based dose calculation accuracy in bone regions. Mean dose error was reduced from 47.5\% to 10.9\%.
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Affiliation(s)
- Yanqi Huang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas, UNITED STATES
| | - Xiaoyu Hu
- The University of Texas Southwestern Medical Center, Dallas, Texas, UNITED STATES
| | - Yuncheng Zhong
- Department of Radiation Oncology, University of Texas Southwestern Medical Centre, Dallas, Texas, UNITED STATES
| | - Youfang Lai
- Radiation Oncology, UT Southwestern Medical, Dallas, UNITED STATES
| | - Chenyang Shen
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, Texas, UNITED STATES
| | - Xun Jia
- Department of Radiation Oncology, UT Southwestern Medical Center, 6363 Forest Park Rd. BL10.202G, MC9315, Dallas, Texas, 75390-9315, UNITED STATES
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11
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Ordóñez-Sanz C, Cowen M, Shiravand N, MacDougall ND. CBCT imaging: a simple approach for optimising and evaluating concomitant imaging doses, based on patient-specific attenuation, during radiotherapy pelvis treatment. Br J Radiol 2021; 94:20210068. [PMID: 34282947 PMCID: PMC8523193 DOI: 10.1259/bjr.20210068] [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] [Indexed: 11/15/2022] Open
Abstract
Objectives: A simple, robust method, for optimising cone-beam CT (CBCT) dose and image quality for pelvis treatment, based on patient-specific attenuation. Methods: Methods were investigated for grouping patients into four imaging categories (small [S], medium [M], large [L], extra large [XL]), based on planning-CT CTDIvol, and phantoms constructed to represent each group. CBCTs with varying kV, mA and ms honed in on the best settings, with a bladder noise of 25 HU. A patient pilot study clinically verified the new imaging settings. Results: The planning CTDIvol is a reliable method for grouping patients. Phantom measurements from the S, M and L groups show doses significantly reduced (19–83% reduction), whilst the XL group required an increase of 39%. Phantom TLD measurements showed the number of scans needed to increase rectal organ at risk (OAR) dose by 1 Gy was 143 (S group) and 50 (M group). Images were qualitatively assessed as sufficient by clinicians. Conclusion: Patient-specific CBCT modes are in use clinically with dose reductions across all modes except Pelvis XL, keeping doses ALARP and images optimal. Consideration of OAR doses controls the number of CBCTs allowed to ensure adherence to OAR tolerance. Reporting CBCT doses in “scans per Gray” allows clinicians to make informed decisions regarding the imaging schedule and concomitant doses. Advances in knowledge: Patient grouping at planning CT, using CTDIvol, allows for CBCT imaging protocols to be selected based on patient specific attenuation. Reporting OAR doses in terms of “scans per Gray” allows translation of imaging dose risk to the Oncologist.
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Affiliation(s)
| | - Mark Cowen
- North West Anglia NHS Foundation Trust, England, UK
| | - Neda Shiravand
- Radiotherapy Physics, St Bartholomew's Hospital, London, UK
| | - Niall D MacDougall
- Radiotherapy Physics, St Bartholomew's Hospital, London, UK.,Barts Cancer Institute, Queen Mary University of London, London, UK
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12
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Duan YH, Gu HL, Yang XH, Chen H, Wang H, Shao Y, Li XY, Feng AH, Ying YC, Fu XL, Ma K, Zhou T, Xu ZY. Evaluation of IGRT-Induced Imaging Doses and Secondary Cancer Risk for SBRT Early Lung Cancer Patients In Silico Study. Technol Cancer Res Treat 2021; 20:15330338211016472. [PMID: 34184567 PMCID: PMC8251513 DOI: 10.1177/15330338211016472] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Objectives: This study performed dosimetry studies and secondary cancer risk assessments on using electronic portal imaging device (EPID) and cone beam computed tomography (CBCT) as image guided tools for the early lung cancer patients treated with SBRT. Methods: The imaging doses from MV-EPID and kV-CBCT of the Edge accelerator were retrospectively added to sixty-one SBRT treatment plans of early lung cancer patients. The MV-EPID imaging dose (6MV Photon beam) was calculated in Pinnacle TPS, and the kV-CBCT imaging dose was simulated and calculated by modeling of the kV energy beam in TPS using Pinnacle automatic modeling program. Three types of plans, namely PlanEPID, PlanCBCT and Planorigin, were generated with incorporating doses of EPID, CBCT and no imaging, respectively, for analysis. The effects of imaging doses on dose-volume-histogram (DVH) and plan quality were analyzed, and the excess absolute risk (EAR) of secondary cancer for ipsilateral lung was evaluated. Results: The regions that received less than 50 cGy were significantly impacted by the imaging doses, while the isodose lines greater than 1000 cGy were barely changed. The DVH values of ipsilateral lung increased the most in PlanEPID, followed by PlanCBCT. Compared to Planorigin on the average, the estimated EAR of ipsilateral lung in PlanEPID increased by 3.43%, while the corresponding EAR increase in PlanCBCT was much smaller (about 0.4%). Considering only the contribution of the imaging dose, the EAR values for the ipsilateral lung due to the MV-EPID dose in 5 years,10 years and 15 years were 1.49 cases, 2.09 cases and 2.88 cases per 104PY respectively, and those due to the kV-CBCT dose were about 9 times lower, correspondingly. Conclusions: The imaging doses produced by MV-EPID and kV-CBCT had little effects on the target dose coverage. The secondary cancer risk caused by MV-EPID dose is more than 8.5 times that of kV-CBCT.
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Affiliation(s)
- Yan-Hua Duan
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Heng-Le Gu
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Hui Yang
- Department of Engineering, Beijing Jingfang Technologies Co. Ltd, Beijing, China
| | - Hua Chen
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Hao Wang
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Yan Shao
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Yang Li
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Ai-Hui Feng
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Yan-Chen Ying
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Long Fu
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Kui Ma
- Clinical helpdesk, Varian Medical Systems, China
| | - Tao Zhou
- Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Shandong, China
| | - Zhi-Yong Xu
- Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China
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13
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Heidarloo N, Aghamiri SMR, Saghamanesh S, Azma Z, Alaei P. Generation of material-specific energy deposition kernels for kilovoltage x-ray dose calculations. Med Phys 2021; 48:5423-5439. [PMID: 34173989 DOI: 10.1002/mp.15061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 11/10/2022] Open
Abstract
PURPOSE Dose calculation of kilovoltage x rays used in Image-Guided Radiotherapy has been investigated in recent years using various methods. Among these methods are model-based ones that suffer from inaccuracies in high-density materials and at interfaces when used in the kilovoltage energy range. The main reason for this is the use of water energy deposition kernels and simplifications employed such as density scaling in heterogeneous media. The purpose of this study was to produce and characterize material-specific energy deposition kernels, which could be used for dose calculations in this energy range. These kernels will also have utility in dose calculations in superficial radiation therapy and orthovoltage beams utilized in small animal irradiators. METHODS Water energy deposition kernels with various resolutions; and high-resolution, material-specific energy deposition kernels were generated in the energy range of 10-150 kVp, using the EGSnrc Monte Carlo toolkit. The generated energy deposition kernels were further characterized by calculating the effective depth of penetration, the effective radial distance, and the effective lateral distance. A simple benchmarking of the kernels against Monte Caro calculations has also been performed. RESULTS There was good agreement with previously reported water kernels, as well as between kernels with different resolution. The evaluation of effective depth of penetration, and radial and laterals distances, defines the relationship between energy, material density, and the shape of the material-specific kernels. The shape of these kernels becomes more forwardly scattered as the energy and material density are increased. The comparison of the dose calculated using the kernels with Monte Carlo provides acceptable results. CONCLUSIONS Water and material-specific energy deposition kernels in the kilovoltage energy range have been generated, characterized, and compared to previous work. These kernels will have utility in dose calculations in this energy range once algorithms capable of employing them are fully developed.
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Affiliation(s)
- Nematollah Heidarloo
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran
| | | | - Somayeh Saghamanesh
- Center for X-ray Analytics, Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland
| | - Zohreh Azma
- Department of Medical Radiation Engineering, Shahid Beheshti University, Tehran, Iran.,Erfan Radiation Oncology Center, Erfan-Niyayesh Hospital, Iran University of Medical Science, Tehran, Iran
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, MN, USA
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14
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Darvish-Molla S, Spurway A, Sattarivand M. Comprehensive characterization of ExacTrac stereoscopic image guidance system using Monte Carlo and Spektr simulations. Phys Med Biol 2020; 65:245029. [PMID: 32392546 DOI: 10.1088/1361-6560/ab91d8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The purpose of this work is to develop accurate computational methods to comprehensively characterize and model the clinical ExacTrac imaging system, which is used as an image guidance system for stereotactic treatment applications. The Spektr toolkit was utilized to simulate the spectral and imaging characterization of the system. Since Spektr only simulates the primary beam (ignoring scatter), a full model of ExacTrac was also developed in Monte Carlo (MC) to characterize the imaging system. To ensure proper performance of both simulation models, Spektr and MC data were compared to the measured spectral and half value layers (HVLs) values. To validate the simulation results, x-ray spectra of the ExacTrac system were measured for various tube potentials using a CdTe spectrometer with multiple added narrow collimators. The raw spectra were calibrated using a 57Co source and corrected for the escape peaks and detector efficiency. HVLs in mm of Al for various energies were measured using a calibrated RaySafe detector. Spektr and MC HVLs were calculated and compared to the measured values. The patient surface dose was calculated for different clinical imaging protocols from the measured air kerma and HVL values following the TG-61 methodology. The x-ray focal spot was measured by slanted edge technique using gafchromic films. ExacTrac imaging system beam profiles were simulated for various energies by MC simulation and the results were benchmarked by experimentally acquired beam profiles using gafchromic films. The effect of 6D IGRT treatment couch on beam hardening, dynamic range of the flat panel detector and scatter effect were determined using both Spektr simulation and experimental measurements. The measured and simulated spectra (of both MC and Spektr) for various kVps were compared and agreed within acceptable error. As another validation, the measured HVLs agreed with the Spektr and MC simulated HVLs on average within 1.0% for all kVps. The maximum and minimum patient surface doses were found to be 1.06 mGy for shoulder (high) and 0.051 mGy for cranial (low) imaging protocols, respectively. The MC simulated beam profiles were well matched with experimental results and replicated the penumbral slopes, the heel effect, and out-of-field regions. Dynamic range of detector (in terms of air kerma at detector surface) was found to be in the range of [6.1 × 10-6, 5.3 × 10-3] mGy. Accurate MC and Spektr models of the ExacTrac image guidance system were successfully developed and benchmarked via experimental validation. While patient surface dose for available imaging protocols were reported in this study, the established MC model may be used to obtain 3D imaging dose distribution for real patient geometries.
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Affiliation(s)
- Sahar Darvish-Molla
- Department of Medical Physics, Juravinski Cancer Centre at Hamilton Health Sciences, Hamilton, ON, Canada. Author to whom any correspondence should be addressed
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15
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Bryce-Atkinson A, de Jong R, Bel A, Aznar MC, Whitfield G, van Herk M. Evaluation of Ultra-low-dose Paediatric Cone-beam Computed Tomography for Image-guided Radiotherapy. Clin Oncol (R Coll Radiol) 2020; 32:835-844. [PMID: 33067079 DOI: 10.1016/j.clon.2020.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/11/2020] [Accepted: 09/29/2020] [Indexed: 01/01/2023]
Abstract
AIMS In image-guided radiotherapy, daily cone-beam computed tomography (CBCT) is rarely applied to children due to concerns over imaging dose. Simulating low-dose CBCT can aid clinical protocol design by allowing visualisation of new scan protocols in patients without delivering additional dose. This work simulated ultra-low-dose CBCT and evaluated its use for paediatric image-guided radiotherapy by assessment of image registration accuracy and visual image quality. MATERIALS AND METHODS Ultra-low-dose CBCT was simulated by adding the appropriate amount of noise to projection images prior to reconstruction. This simulation was validated in phantoms before application to paediatric patient data. Scans from 20 patients acquired at our current clinical protocol (0.8 mGy) were simulated for a range of ultra-low doses (0.5, 0.4, 0.2 and 0.125 mGy) creating 100 scans in total. Automatic registration accuracy was assessed in all 100 scans. Inter-observer registration variation was next assessed for a subset of 40 scans (five scans at each simulated dose and 20 scans at the current clinical protocol). This subset was assessed for visual image quality by Likert scale grading of registration performance and visibility of target coverage, organs at risk, soft-tissue structures and bony anatomy. RESULTS Simulated and acquired phantom scans were in excellent agreement. For patient scans, bony atomy registration discrepancies for ultra-low-dose scans fell within 2 mm (translation) and 1° (rotation) compared with the current clinical protocol, with excellent inter-observer agreement. Soft-tissue registration showed large discrepancies. Bone visualisation and registration performance reached over 75% acceptability (rated 'well' or 'very well') down to the lowest doses. Soft-tissue visualisation did not reach this threshold for any dose. CONCLUSION Ultra-low-dose CBCT was accurately simulated and evaluated in patient data. Patient scans simulated down to 0.125 mGy were appropriate for bony anatomy set-up. The large dose reduction could allow for more frequent (e.g. daily) image guidance and, hence, more accurate set-up for paediatric radiotherapy.
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Affiliation(s)
- A Bryce-Atkinson
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
| | - R de Jong
- Department of Radiation Oncology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - A Bel
- Department of Radiation Oncology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - M C Aznar
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | - G Whitfield
- Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, UK; The Children's Brain Tumour Research Network, The University of Manchester, Royal Manchester Children's Hospital, Manchester, UK
| | - M van Herk
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
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16
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Alcorn SR, Zhou XC, Bojechko C, Rubo RA, Chen MJ, Dieckmann K, Ermoian RP, Ford EC, Kobyzeva D, MacDonald SM, McNutt TR, Nechesnyuk A, Nilsson K, Sjostrand H, Smith KS, Stock M, Tryggestad EJ, Villar RC, Winey BA, Terezakis SA. Low-Dose Image-Guided Pediatric CNS Radiation Therapy: Final Analysis From a Prospective Low-Dose Cone-Beam CT Protocol From a Multinational Pediatrics Consortium. Technol Cancer Res Treat 2020; 19:1533033820920650. [PMID: 32329413 PMCID: PMC7225835 DOI: 10.1177/1533033820920650] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Background: Lower-dose cone-beam computed tomography protocols for image-guided radiotherapy may permit target localization while minimizing radiation exposure. We prospectively evaluated a lower-dose cone-beam protocol for central nervous system image-guided radiotherapy across a multinational pediatrics consortium. Methods: Seven institutions prospectively employed a lower-dose cone-beam computed tomography central nervous system protocol (weighted average dose 0.7 mGy) for patients ≤21 years. Treatment table shifts between setup with surface lasers versus cone-beam computed tomography were used to approximate setup accuracy, and vector magnitudes for these shifts were calculated. Setup group mean, interpatient, interinstitution, and random error were estimated, and clinical factors were compared by mixed linear modeling. Results: Among 96 patients, with 2179 pretreatment cone-beam computed tomography acquisitions, median age was 9 years (1-20). Setup parameters were 3.13, 3.02, 1.64, and 1.48 mm for vector magnitude group mean, interpatient, interinstitution, and random error, respectively. On multivariable analysis, there were no significant differences in mean vector magnitude by age, gender, performance status, target location, extent of resection, chemotherapy, or steroid or anesthesia use. Providers rated >99% of images as adequate or better for target localization. Conclusions: A lower-dose cone-beam computed tomography protocol demonstrated table shift vector magnitude that approximate clinical target volume/planning target volume expansions used in central nervous system radiotherapy. There were no significant clinical predictors of setup accuracy identified, supporting use of this lower-dose cone-beam computed tomography protocol across a diverse pediatric population with brain tumors.
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Affiliation(s)
| | - Xian Chiong Zhou
- The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | | | | | - Michael J Chen
- Grupo de Apoio ao Adolescente e à Criança com Câncer, São Paulo, Brazil
| | - Karin Dieckmann
- Universität Klinik Für Strahlentherapie und Strahlenbiologie, Vienna, Austria
| | | | | | - Daria Kobyzeva
- Federal Scientific Clinical Center of Children's Hematology, Oncology and Immunology, Moscow, Russia
| | | | | | - Alexey Nechesnyuk
- Federal Scientific Clinical Center of Children's Hematology, Oncology and Immunology, Moscow, Russia
| | | | | | | | - Markus Stock
- Universität Klinik Für Strahlentherapie und Strahlenbiologie, Vienna, Austria
| | | | | | | | - Stephanie A Terezakis
- Department of Radiation Oncology and Molecular Radiation Sciences, University of Minnesota, Minneapolis, MN, USA
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17
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Daily computed tomography image guidance: Dosimetric advantages outweigh low-dose radiation exposure for treatment of mediastinal lymphoma. Radiother Oncol 2020; 152:14-18. [DOI: 10.1016/j.radonc.2020.06.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/29/2020] [Accepted: 06/19/2020] [Indexed: 11/23/2022]
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18
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Hua CH, Vern-Gross TZ, Hess CB, Olch AJ, Alaei P, Sathiaseelan V, Deng J, Ulin K, Laurie F, Gopalakrishnan M, Esiashvili N, Wolden SL, Krasin MJ, Merchant TE, Donaldson SS, FitzGerald TJ, Constine LS, Hodgson DC, Haas-Kogan DA, Mahajan A, Laack N, Marcus KJ, Taylor PA, Ahern VA, Followill DS, Buchsbaum JC, Breneman JC, Kalapurakal JA. Practice patterns and recommendations for pediatric image-guided radiotherapy: A Children's Oncology Group report. Pediatr Blood Cancer 2020; 67:e28629. [PMID: 32776500 PMCID: PMC7774502 DOI: 10.1002/pbc.28629] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 06/16/2020] [Accepted: 07/19/2020] [Indexed: 12/18/2022]
Abstract
This report by the Radiation Oncology Discipline of Children's Oncology Group (COG) describes the practice patterns of pediatric image-guided radiotherapy (IGRT) based on a member survey and provides practice recommendations accordingly. The survey comprised of 11 vignettes asking clinicians about their recommended treatment modalities, IGRT preferences, and frequency of in-room verification. Technical questions asked physicists about imaging protocols, dose reduction, setup correction, and adaptive therapy. In this report, the COG Radiation Oncology Discipline provides an IGRT modality/frequency decision tree and the expert guidelines for the practice of ionizing image guidance in pediatric radiotherapy patients.
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Affiliation(s)
- Chia-ho Hua
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | | | - Clayton B. Hess
- Department of Radiation Oncology, Massachusetts General Hospital, Boston, Massachusetts
- Department of Radiation Oncology, Emory University, Atlanta, Georgia
| | - Arthur J. Olch
- Department of Radiation Oncology, University of Southern California and Children’s Hospital of Los Angeles, Los Angeles, California
| | - Parham Alaei
- Department of Radiation Oncology, University of Minnesota, Minneapolis, Minnesota
| | | | - Jun Deng
- Department of Therapeutic Radiology, Yale University, New Haven, Connecticut
| | - Kenneth Ulin
- Department of Radiation Oncology, University of Massachusetts, Worcester, Massachusetts
| | - Fran Laurie
- Department of Radiation Oncology, University of Massachusetts, Worcester, Massachusetts
| | | | - Natia Esiashvili
- Department of Radiation Oncology, Emory University, Atlanta, Georgia
| | - Suzanne L. Wolden
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Matthew J. Krasin
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Thomas E Merchant
- Department of Radiation Oncology, St. Jude Children’s Research Hospital, Memphis, Tennessee
| | - Sarah S. Donaldson
- Department of Radiation Oncology, Stanford University, Stanford, California
| | - Thomas J. FitzGerald
- Department of Radiation Oncology, University of Massachusetts, Worcester, Massachusetts
| | - Louis S. Constine
- Department of Radiation Oncology, University of Rochester, Rochester, New York
| | - David C. Hodgson
- Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Daphne A. Haas-Kogan
- Department of Radiation Oncology, Dana Farber Cancer Institute/Boston Children’s Hospital, Boston, Massachusetts
| | - Anita Mahajan
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Nadia Laack
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota
| | - Karen J. Marcus
- Department of Radiation Oncology, Dana Farber Cancer Institute/Boston Children’s Hospital, Boston, Massachusetts
| | - Paige A Taylor
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Verity A Ahern
- Department of Radiation Oncology, Children’s Hospital at Westmead, Sydney, Australia
| | - David S. Followill
- Department of Radiation Physics, Division of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jeffrey C. Buchsbaum
- Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, Maryland
| | - John C. Breneman
- Department of Radiation Oncology, University of Cincinnati, Cincinnati, Ohio
| | - John A. Kalapurakal
- Department of Radiation Oncology, Northwestern University, Chicago, Illinois
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19
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Kearney M, Coffey M, Leong A. A review of Image Guided Radiation Therapy in head and neck cancer from 2009-201 - Best Practice Recommendations for RTTs in the Clinic. Tech Innov Patient Support Radiat Oncol 2020; 14:43-50. [PMID: 32566769 PMCID: PMC7296359 DOI: 10.1016/j.tipsro.2020.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/17/2020] [Accepted: 02/11/2020] [Indexed: 02/06/2023] Open
Abstract
Radiation therapy (RT) is beneficial in Head and Neck Cancer (HNC) in both the definitive and adjuvant setting. Highly complex and conformal planning techniques are becoming standard practice in delivering increased doses in HNC. A sharp falloff in dose outside the high dose area is characteristic of highly complex techniques and geometric uncertainties must be minimised to prevent under dosage of the target volume and possible over dosage of surrounding critical structures. CTV-PTV margins are employed to account for geometric uncertainties such as set up errors and both interfraction and intrafraction motion. Robust immobilisation and Image Guided Radiation Therapy (IGRT) is also essential in this group of patients to minimise discrepancies in patient position during the treatment course. IGRT has evolved with increased 2-Dimensional (2D) and 3-Dimensional (3D) IGRT modalities available for geometric verification. 2D and 3D IGRT modalities are both beneficial in geometric verification while 3D imaging is a valuable tool in assessing volumetric changes that may have dosimetric consequences for this group of patients. IGRT if executed effectively and efficiently provides clinicians with confidence to reduce CTV-PTV margins thus limiting treatment related toxicities in patients. Accumulated exposure dose from IGRT vary considerably and may be incorporated into the treatment plan to avoid excess dose. However, there are considerable variations in the application of IGRT in RT practice. This paper aims to summarise the advances in IGRT in HNC treatment and provide clinics with recommendations for an IGRT strategy for HNC in the clinic.
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Affiliation(s)
- Maeve Kearney
- Applied Radiation Therapy Trinity, Discipline of Radiation Therapy, Trinity College, Dublin 2, Ireland
| | - Mary Coffey
- Applied Radiation Therapy Trinity, Discipline of Radiation Therapy, Trinity College, Dublin 2, Ireland
| | - Aidan Leong
- Department of Radiation Therapy, University of Otago, Wellington, New Zealand.,Bowen Icon Cancer Centre, Wellington, New Zealand
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20
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Boissonnat G, Chesneau H, Barat E, Dautremer T, Garcia-Hernandez JC, Lazaro D. Validation of histogram-based virtual source models for different IGRT kV-imaging systems. Med Phys 2020; 47:4531-4542. [PMID: 32497267 DOI: 10.1002/mp.14311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 05/24/2020] [Accepted: 05/26/2020] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Image-guided radiotherapy (IGRT) improves tumor control but its intensive use may entrain late side effects caused by the additional imaging doses. There is a need to better quantify the additional imaging doses, so they can be integrated in the therapeutic workflow. Currently, no dedicated software enables to compute patient-specific imaging doses on a wide range of systems and protocols. As a first step toward this objective, we propose a common methodology to model four different kV-imaging systems used in radiotherapy (Varian's OBI, Elekta's XVI, Brainlab's ExacTrac, and Accuray's Cyberknife) using a new type of virtual source model based on Monte Carlo calculations. METHODS We first describe our method to build a simplified description of the photon output, or virtual source models (VSMs), of each imaging system. Instead of being constructed using measurement data, as it is most commonly the case, our VSM is used as the summary of the phase-space files (PSFs) resulting from a first Monte Carlo simulation of the considered x-ray tube. Second, the VSM is used as a photon generator for a second MC simulation in which we compute the dose. Then, the proposed VSM is thoroughly validated against standard MC simulation using PSFs on the XVI system. Last, each modeled system is compared to profiles and depth-dose-curve measurements performed in homogeneous phantom. RESULTS Comparisons between PSF-based and VSM-based calculations highlight that VSMs could provide equivalent dose results (within 1% of difference) than PSFs inside the imaging field-of-view (FOV). In contrast, VSMs tend to underestimate (for up to 20%) calculated doses outside of the imaging FOV due to the assumptions underlying the VSM construction. In addition, we showed that the use of VSMs allows reducing calculation time by at least a factor of 2.8. Indeed, for identical simulation times, statistical uncertainties on dose distributions computed using VSMs were much lower than those obtained from PSF-based calculations. CONCLUSIONS For each of the four imaging systems, VSMs were successfully validated against measurements in homogeneous phantoms, and are therefore ready to be used for future preclinical studies in heterogeneous or anthropomorphic phantoms. The cross system modeling methodology developed here should enable, later on, to estimate precisely and accurately patient-specific 3D dose maps delivered during a large range of kV-imaging procedures.
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Affiliation(s)
- G Boissonnat
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - H Chesneau
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - E Barat
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | - T Dautremer
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
| | | | - D Lazaro
- CEA, LIST, System Modelling and Simulation Lab, Gif-sur-Yvette, F-91191, France
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Tomita T, Isobe T, Furuyama Y, Takei H, Kobayashi D, Mori Y, Terunuma T, Sato E, Yokota H, Sakae T. Evaluation of Dose Distribution and Normal Tissue Complication Probability of a Combined Dose of Cone-Beam Computed Tomography Imaging with Treatment in Prostate Intensity-Modulated Radiation Therapy. J Med Phys 2020; 45:78-87. [PMID: 32831490 PMCID: PMC7416863 DOI: 10.4103/jmp.jmp_4_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 03/02/2020] [Accepted: 03/31/2020] [Indexed: 12/03/2022] Open
Abstract
Purpose: The purpose of this study is to evaluate the effects of cone-beam computed tomography (CBCT) on dose distribution and normal tissue complication probability (NTCP) by constructing a comprehensive dose evaluation system for prostate intensity-modulated radiation therapy (IMRT). Methods: A system that could combine CBCT and treatment doses with MATLAB was constructed. Twenty patients treated with prostate IMRT were studied. A mean dose of 78 Gy was prescribed to the prostate region, excluding the rectal volume from the target volume, with margins of 4 mm to the dorsal side of the prostate and 7 mm to the entire circumference. CBCT and treatment doses were combined, and the dose distribution and the NTCP of the rectum and bladder were evaluated. Results: The radiation dose delivered to 2% and 98% of the target volume increased by 0.90 and 0.74 Gy on average, respectively, in the half-fan mode and on average 0.76 and 0.72 Gy, respectively, in the full-fan mode. The homogeneity index remained constant. The percent volume of the rectum and bladder irradiated at each dose increased slightly, with a maximum increase of <1%. The rectal NTCP increased by approximately 0.07% from 0.46% to 0.53% with the addition of a CBCT dose, while the maximum NTCP in the bladder was approximately 0.02%. Conclusions: This study demonstrated a method to evaluate a combined dose of CBCT and a treatment dose using the constructed system. The combined dose distribution revealed increases of <1% volume in the rectal and bladder doses and approximately 0.07% in the rectal NTCP.
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Affiliation(s)
- Tetsuya Tomita
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.,Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Tomonori Isobe
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | | | - Hideyuki Takei
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | - Daisuke Kobayashi
- Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, Japan.,Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Yutaro Mori
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
| | | | - Eisuke Sato
- Faculty of Health Sciences, Juntendo University, Tokyo, Japan
| | - Hiroshi Yokota
- Department of Radiology, University of Tsukuba Hospital, Ibaraki, Japan
| | - Takeji Sakae
- Faculty of Medicine, University of Tsukuba, Ibaraki, Japan
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Technical note: improved positioning protocol for patient setup accuracy in conventional radiotherapy for lung cancer. Radiol Phys Technol 2019; 12:426-432. [PMID: 31549292 DOI: 10.1007/s12194-019-00537-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 12/31/2022]
Abstract
This study aimed to investigate an improved setup protocol for maintaining patient setup accuracy, with minimal or no use of image-guided radiation therapy in conventional radiotherapy for lung cancer. A coordinate value for the treatment couch in the anterior-posterior (AP) direction was obtained from the first fraction using bony anatomy image guidance. The coordinate value was invariably used for patient positioning in the second and subsequent treatment fractions. The errors of 2410 setup image sets (anterior and lateral) from 105 patients with lung cancer were analyzed. The systematic and random patient positioning errors in the AP direction were 0.6 ± 1.0 mm. Such errors accounted for 97% of all fractions within ± 2 mm. The protocol resulted in minimal patient setup errors in the AP direction using only one image for guidance; therefore, it may be applied to conventional radiotherapy for lung cancer in case of insufficient image guidance.
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Posiewnik M, Piotrowski T. A review of cone-beam CT applications for adaptive radiotherapy of prostate cancer. Phys Med 2019; 59:13-21. [DOI: 10.1016/j.ejmp.2019.02.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 01/29/2019] [Accepted: 02/15/2019] [Indexed: 11/26/2022] Open
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Bell K, Licht N, Rübe C, Dzierma Y. Image guidance and positioning accuracy in clinical practice: influence of positioning errors and imaging dose on the real dose distribution for head and neck cancer treatment. Radiat Oncol 2018; 13:190. [PMID: 30285806 PMCID: PMC6167812 DOI: 10.1186/s13014-018-1141-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 09/24/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Modern radiotherapy offers the possibility of highly accurate tumor treatment. To benefit from this precision at its best, regular positioning verification is necessary. By the use of image-guided radiotherapy and the application of safety margins the influence of positioning inaccuracies can be counteracted. In this study the effect of additional imaging dose by set-up verification is compared with the effect of dose smearing by positioning inaccuracies for a collective of head-and-neck cancer patients. METHODS This study is based on treatment plans of 40 head-and-neck cancer patients. To evaluate the imaging dose several image guidance scenarios with different energies, techniques and frequencies were simulated and added to the original plan. The influence of the positioning inaccuracies was assessed by the use of real applied table shifts for positioning. The isocenters were shifted back appropriately to these values to simulate that no positioning correction had been performed. For the single fractions the shifted plans were summed considering three different scenarios: The summation of only shifted plans, the consideration of the original plan for the fractions with set-up verification, and the addition of the extra imaging dose to the latter. For both effects (additional imaging dose and dose smearing), plans were analyzed and compared considering target coverage, sparing of organs at risk (OAR) and normal tissue complication probability (NTCP). RESULTS Daily verification of the patient positioning using 3D imaging with MV energies result in non-negligible high doses. kV imaging has only marginal influence on plan quality, primarily related to sparing of organs at risk, even with daily 3D imaging. For this collective, sparing of organs at risk and NTCP are worse due to potential positioning errors. CONCLUSION Regular set-up verification is essential for precise radiation treatment. Relating to the additional dose, the use of kV modalities is uncritical for any frequency and technique. Dose smearing due to positioning errors for this collective mainly resulted in a decrease of OAR sparing. Target coverage also suffered from the positioning inaccuracies, especially for individual patients. Taking into account both examined effects the relevance of an extensive IGRT is clearly present, even at the expense of additional imaging dose and time expenditure.
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Affiliation(s)
- Katharina Bell
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5/Saar, D-66421 Homburg, Germany
| | - Norbert Licht
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5/Saar, D-66421 Homburg, Germany
| | - Christian Rübe
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5/Saar, D-66421 Homburg, Germany
| | - Yvonne Dzierma
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5/Saar, D-66421 Homburg, Germany
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Ardenfors O, Henry T, Gudowska I, Poludniowski G, Dasu A. Organ doses from a proton gantry-mounted cone-beam computed tomography system characterized with MCNP6 and GATE. Phys Med 2018; 53:56-61. [PMID: 30241755 DOI: 10.1016/j.ejmp.2018.08.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/08/2018] [Accepted: 08/12/2018] [Indexed: 12/15/2022] Open
Abstract
PURPOSE To determine organ doses from a proton gantry-mounted cone-beam computed tomography (CBCT) system using two Monte Carlo codes and to study the influence on organ doses from different acquisition modes and repeated imaging. METHODS The CBCT system was characterized with MCNP6 and GATE using measurements of depth doses in water and spatial profiles in air. The beam models were validated against absolute dose measurements and used to simulate organ doses from CBCT imaging with head, thorax and pelvis protocols. Anterior and posterior 190° scans were simulated and the resulting organ doses per mAs were compared to those from 360° scans. The influence on organ doses from repeated imaging with different imaging schedules was also investigated. RESULTS The agreement between MCNP6, GATE and measurements with regard to depth doses and beam profiles was within 4% for all protocols and the corresponding average agreement in absolute dose validation was 4%. Absorbed doses for in-field organs from 360° scans ranged between 6 and 8 mGy, 15-17 mGy and 24-54 mGy for the head, thorax and pelvis protocols, respectively. Cumulative organ doses from repeated CBCT imaging ranged between 0.04 and 0.32 Gy for weekly imaging and 0.2-1.6 Gy for daily imaging. The anterior scans resulted in an average increase in dose per mAs of 24% to the organs of interest relative to the 360° scan, while the posterior scan showed a 37% decrease. CONCLUSIONS A proton gantry-mounted CBCT system was accurately characterized with MCNP6 and GATE. Organ doses varied greatly depending on acquisition mode, favoring posterior scans.
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Affiliation(s)
- Oscar Ardenfors
- Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden.
| | - Thomas Henry
- Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden
| | - Irena Gudowska
- Medical Radiation Physics, Department of Physics, Stockholm University, Stockholm, Sweden
| | - Gavin Poludniowski
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden
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Dzierma Y, Mikulla K, Richter P, Bell K, Melchior P, Nuesken F, Rübe C. Imaging dose and secondary cancer risk in image-guided radiotherapy of pediatric patients. Radiat Oncol 2018; 13:168. [PMID: 30185206 PMCID: PMC6125956 DOI: 10.1186/s13014-018-1109-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 08/21/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Daily image-guided radiotherapy (IGRT) can contribute to cover extended body volumes with low radiation dose. The effect of additional imaging dose on secondary cancer development is modelled for a collective of children with Morbus Hodgkin. METHODS Eleven radiotherapy treatment plans from pediatric patients with Hodgkin's lymphoma were retrospectively analyzed, including imaging dose from scenarios using different energies (kV/MV) and planar/cone-beam computed tomography (CBCT) techniques. In addition to assessing the effect of imaging dose on organs at risk, the excess average risk (EAR) for developing a secondary carcinoma of the lung or breast was modelled. RESULTS Although the variability between the patients is relatively large due to the different target volumes, the additional EAR due to imaging can be consistently determined. For daily 6MV CBCT, the EAR for developing a secondary cancer at age 50 is over 3 cases per 104 PY (patient-years) for the female breast and 0.7-0.8 per 104 PY for the lungs. This can be decreased by using only planar images (< 1 per 104 PY for the breast and 0.1 for the lungs). Similar values are achieved by daily 360° kV CBCT (0.44-0.57 per 104 PY for the breast and 0.08 per 104 PY for the lungs), which is again reduced for daily 200° kV CBCT (0.02 per 104 PY for the lungs and 0.07-0.08 per 104 PY for the breast). These values increase if an older attained age is considered (e.g., for 70 years, by a factor of four for the lungs). CONCLUSIONS Daily imaging can be performed with an additional secondary cancer risk of less than 1 per 104 PY if kV CBCT is applied. If MV modalities must be chosen, a similar EAR can be achieved with planar images. A further reduction in risk is possible if the imaging geometry allows for sparing of the breast by a partial rotation underneath the patient.
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Affiliation(s)
- Yvonne Dzierma
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Katharina Mikulla
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Patrick Richter
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Katharina Bell
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Patrick Melchior
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Frank Nuesken
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
| | - Christian Rübe
- Department of Radiotherapy and Radiation Oncology, Saarland University Medical Centre, Kirrberger Str. Geb. 6.5, 66421 Homburg, Saar Germany
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Ardenfors O, Dasu A, Lillhök J, Persson L, Gudowska I. Out-of-field doses from secondary radiation produced in proton therapy and the associated risk of radiation-induced cancer from a brain tumor treatment. Phys Med 2018; 53:129-136. [DOI: 10.1016/j.ejmp.2018.08.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 06/27/2018] [Accepted: 08/30/2018] [Indexed: 02/07/2023] Open
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Ardenfors O, Gudowska I, Flejmer AM, Dasu A. Impact of irradiation setup in proton spot scanning brain therapy on organ doses from secondary radiation. RADIATION PROTECTION DOSIMETRY 2018; 180:261-266. [PMID: 30085315 DOI: 10.1093/rpd/ncy013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 01/16/2018] [Indexed: 06/08/2023]
Abstract
A Monte Carlo model of a proton spot scanning pencil beam was used to simulate organ doses from secondary radiation produced from brain tumour treatments delivered with either a lateral field or a vertex field to one adult and one paediatric patient. Absorbed doses from secondary neutrons, photons and protons and neutron equivalent doses were higher for the vertex field in both patients, but the differences were low in absolute terms. Absorbed doses ranged between 0.1 and 43 μGy.Gy-1 in both patients with the paediatric patient receiving higher doses. The neutron equivalent doses to the organs ranged between 0.5 and 141 μSv.Gy-1 for the paediatric patient and between 0.2 and 134 μSv.Gy-1 for the adult. The highest neutron equivalent dose from the entire treatment was 7 mSv regardless of field setup and patient size. The results indicate that different field setups do not introduce large absolute variations in out-of-field doses produced in patients undergoing proton pencil beam scanning of centrally located brain tumours.
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Affiliation(s)
- Oscar Ardenfors
- Medical Radiation Physics, Department of Physics, Stockholm University, Box 260, Stockholm, Sweden
| | - Irena Gudowska
- Medical Radiation Physics, Department of Physics, Stockholm University, Box 260, Stockholm, Sweden
| | - Anna Maria Flejmer
- Department of Oncology and Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
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Ding GX, Alaei P, Curran B, Flynn R, Gossman M, Mackie TR, Miften M, Morin R, Xu XG, Zhu TC. Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180. Med Phys 2018; 45:e84-e99. [PMID: 29468678 DOI: 10.1002/mp.12824] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. AIMS This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. MATERIALS & METHODS We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. RESULTS We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. DISCUSSION Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. CONCLUSION Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.
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Affiliation(s)
- George X Ding
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN, 37232, USA
| | - Parham Alaei
- University of Minnesota, Minneapolis, MN, 55455, USA
| | - Bruce Curran
- Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ryan Flynn
- University of Iowa, Iowa City, IA, 52242, USA
| | | | | | | | | | - X George Xu
- Rensselaer Polytechnic Institute, Troy, NY, 12180, USA
| | - Timothy C Zhu
- University of Pennsylvania, Philadelphia, PA, 19104, USA
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30
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Buckley JG, Wilkinson D, Malaroda A, Metcalfe P. Investigation of the radiation dose from cone-beam CT for image-guided radiotherapy: A comparison of methodologies. J Appl Clin Med Phys 2017; 19:174-183. [PMID: 29265684 PMCID: PMC5768018 DOI: 10.1002/acm2.12239] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/31/2017] [Accepted: 11/03/2017] [Indexed: 12/27/2022] Open
Abstract
Four methodologies were evaluated for quantifying kilovoltage cone‐beam computed tomography (CBCT) dose: the Cone‐Beam Dose Index (CBDI), IAEA Report 5 recommended methodology (IAEA), the AAPM Task Group 111 methodology (TG111), and the current dose metric; the Computed Tomography Dose Index (CTDI) on two commercial Varian cone‐beam CT imaging systems; the Clinac iX On‐Board Imager (OBI); and the TrueBeam X‐ray Imaging system (XI). The TG111 methodology measured the highest overall dose (21.199 ± 0.035 mGy OBI and 22.420 ± 0.002 XI for pelvis imaging) due to the full scatter of the TG111 phantom and was within 5% of CTDI measurements taken using a full scatter TG111 phantom and 30‐cm film strips. CBDI measured the second highest overall dose, within 10% of the TG111, with IAEA measuring the third highest dose. For head CBCT protocols, CBDI measured the highest dose, followed by IAEA. The CTDI method measured lowest across all scan modes highlighting its limitations for CBCT dosimetry. The XI imaging system delivered lower doses for head and thorax scan modes and similar doses to the OBI system for pelvis scan modes due to additional beam hardening filtration in the XI system. The TG111 method measured the highest dose in the center of a CBCT scan during image guidance procedures; however, CBDI provided a good approximation to TG111 with existing CTDI equipment and may be more applicable clinically.
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Affiliation(s)
- Jarryd G Buckley
- School of Physics, Centre for Medical and Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Dean Wilkinson
- Illawarra Cancer Care Centre, Wollongong Hospital, Wollongong, Australia
| | - Alessandra Malaroda
- School of Physics, Centre for Medical and Radiation Physics, University of Wollongong, Wollongong, Australia
| | - Peter Metcalfe
- School of Physics, Centre for Medical and Radiation Physics, University of Wollongong, Wollongong, Australia
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Benhalouche S, Bert J, Boussion N, Autret A, Pradier O, Visvikis D. GATE Monte-Carlo Simulation of an MV-CBCT Flat Panel for Synergistic Imaging and Dosimetric Applications in Radiotherapy. IEEE TRANSACTIONS ON RADIATION AND PLASMA MEDICAL SCIENCES 2017. [DOI: 10.1109/trpms.2017.2718545] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kry SF, Bednarz B, Howell RM, Dauer L, Followill D, Klein E, Paganetti H, Wang B, Wuu CS, George Xu X. AAPM TG 158: Measurement and calculation of doses outside the treated volume from external-beam radiation therapy. Med Phys 2017; 44:e391-e429. [DOI: 10.1002/mp.12462] [Citation(s) in RCA: 164] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Revised: 05/17/2017] [Accepted: 05/25/2017] [Indexed: 12/14/2022] Open
Affiliation(s)
- Stephen F. Kry
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Bryan Bednarz
- Department of Medical Physics; University of Wisconsin; Madison WI 53705 USA
| | - Rebecca M. Howell
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Larry Dauer
- Departments of Medical Physics/Radiology; Memorial Sloan-Kettering Cancer Center; New York NY 10065 USA
| | - David Followill
- Department of Radiation Physics; MD Anderson Cancer Center; Houston TX 77054 USA
| | - Eric Klein
- Department of Radiation Oncology; Washington University; Saint Louis MO 63110 USA
| | - Harald Paganetti
- Department of Radiation Oncology; Massachusetts General Hospital and Harvard Medical School; Boston MA 02114 USA
| | - Brian Wang
- Department of Radiation Oncology; University of Louisville; Louisville KY 40202 USA
| | - Cheng-Shie Wuu
- Department of Radiation Oncology; Columbia University; New York NY 10032 USA
| | - X. George Xu
- Department of Mechanical, Aerospace, and Nuclear Engineering; Rensselaer Polytechnic Institute; Troy NY 12180 USA
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Son K, Kim JS, Lee H, Cho S. IMAGING DOSE OF HUMAN ORGANS FROM kV-CBCT IN IMAGE-GUIDED RADIATION THERAPY. RADIATION PROTECTION DOSIMETRY 2017; 175:194-200. [PMID: 27765832 DOI: 10.1093/rpd/ncw285] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/26/2016] [Indexed: 06/06/2023]
Abstract
This study investigates dose distribution due to kV cone-beam computed tomography (CBCT) for the patients undergoing CBCT-based image-guided radiation therapy (IGRT). The kV-CBCT provides an efficient image-guidance tool for acquiring the latest volumetric image of a patient's anatomy, and has been being routinely used in clinics for an accurate treatment setup. Imaging radiation doses resulting from six different acquisition protocols of the on-board imager (OBI) were calculated using a Geant4 Application for Tomographic Emission (GATE) Monte Carlo simulation toolkit, and the absorbed doses by various organs were analyzed for the adult and pediatric numerical XCAT phantoms in this study. The calculated organ doses range from 0.1 to 24.1 mGy in the adult phantom, and from 0.1 to 36.8 mGy in the pediatric one. The imaging organ doses to the pediatric phantom turn out to be consistently higher than those to the adult phantom. It is believed that our results would provide reliable data to the clinicians for their making better decisions on CBCT scanning options and would also provide a platform for developing a new kV-CBCT scanning protocol in conjunction with a low-dose capability.
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Affiliation(s)
- Kihong Son
- Department of Nuclear and Quantum engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Jin Sung Kim
- Department of Radiation Oncology Yonsei Cancer Center, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea
| | - Hoyeon Lee
- Department of Nuclear and Quantum engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
| | - Seungryong Cho
- Department of Nuclear and Quantum engineering, Korea Advanced Institute of Science and Technology, Daejeon, Korea
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Adamson J, Mein S, Meng B, Gunasingha R, Yoon SW, Miles D, Walder H, Fathi Z, Beyer W, Spector N, Gieger TL, Nolan MW, Oldham M. Utilizing a diagnostic kV imaging system for x-ray psoralen activated cancer therapy (X-PACT). Biomed Phys Eng Express 2017. [DOI: 10.1088/2057-1976/aa6e58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hauri P, Hälg RA, Schneider U. Technical Note: Comparison of peripheral patient dose from MR-guided 60 Co therapy and 6 MV linear accelerator IGRT. Med Phys 2017; 44:3788-3793. [PMID: 28437010 DOI: 10.1002/mp.12293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 04/13/2017] [Accepted: 04/14/2017] [Indexed: 11/06/2022] Open
Abstract
PURPOSE The use of X-ray imaging in radiation therapy can give a substantial dose to the patient. A Cobalt machine combined with an magnetic resonance imaging (MRI) was recently introduced to clinical work. One positive aspect of using non-ionizing imaging devices is the reduction of the patient exposure. The purpose of this study was to quantify the difference in out-of-field dose to the patient between the image guided radiation therapy (IGRT) treatment applied with a linear accelerator with cone beam CT (CBCT) equipment and a Cobalt machine combined with an MRI. METHODS The treatment of a rhabdomyosarcoma in the prostate was planned and irradiated using different modalities and radiation therapy machines. The whole-body dose was measured for a 3D-conformal radiation therapy (3DCRT), an intensity-modulated radiation therapy (IMRT), and a volumetric-modulated arc therapy plan applied with a conventional linear accelerator operated at 6 MV beam energy. Additionally, the dose of an IMRT plan applied with a 60 Co machine combined with an MRI was measured. Furthermore, the dose of one CBCT scan using the linear accelerator's on-board imaging system was determined. The 3D dose measurements were performed in an anthropomorphic phantom containing 168 slots for thermoluminescence dosimeters (TLDs). A combination of LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) was used to accurately determine the in- and out-of-field dose. The plans were rescaled to different fractionation schemes (2 Gy, 3 Gy, and 5 Gy fraction dose) and the dose of one CBCT scan was additionally added to the treatment dose per fraction applied with the linear accelerator. The resulting absorbed doses per fraction of the two machines were compared. RESULTS In the target region, all measured treatment plans presented the same magnitude of dose, while the CBCT dose was a factor of 100 smaller. Close to the planned target volume (PTV), the dose from the 60 Co machine was a factor of two higher compared with the 3DCRT + CBCT dose. Up to 45 cm from the PTV, the treatment applied with the 60 Co-sources showed an increased out-of-field dose compared to the linear accelerator + CBCT IGRT treatments. Further away from the PTV in the region where leakage from the gantry head is dominating, the out-of-field dose of the Cobalt machine was smaller compared to the linear accelerator + CBCT. CONCLUSION The peripheral dose of the 60 Co machine combined with an MRI is larger up to 45 cm from the PTV and further away, it is lower than the dose from a linear accelerator + CBCT treatment. The presented fractionation schemes had a marginal impact on the results.
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Affiliation(s)
- Pascal Hauri
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Roger A Hälg
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
| | - Uwe Schneider
- Faculty of Science, University of Zurich, Zurich, Switzerland.,Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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Marchant TE, Joshi KD. Comprehensive Monte Carlo study of patient doses from cone-beam CT imaging in radiotherapy. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2017; 37:13-30. [PMID: 27922831 DOI: 10.1088/1361-6498/37/1/13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Accurate knowledge of ionizing radiation dose from cone-beam CT (CBCT) imaging in radiotherapy is important to allow concomitant risks to be estimated and for justification of imaging exposures. This study uses a Monte Carlo CBCT model to calculate imaging dose for a wide range of imaging protocols for male and female patients. The Elekta XVI CBCT system was modeled using GATE and simulated doses were validated against measurements in a water tank and thorax phantom. Imaging dose was simulated in the male and female ICRP voxel phantoms for a variety of anatomical sites and imager settings (different collimators, filters, full and partial rotation). The resulting dose distributions were used to calculate effective doses for each scan protocol. The Monte Carlo simulated doses agree with validation measurements within 5% and 10% for water tank and thorax phantom respectively. Effective dose for head CBCT scans was generally lower for scans centred on the pituitary than the larynx (0.03 mSv versus 0.06 mSv for male ICRP phantom). Pelvis CBCT scan effective dose was higher for the female than male phantom (5.11 mSv versus 2.80 mSv for M15 collimator scan), principally due to the higher dose received by gonads for the female scan. Medium field of view thorax scan effective doses ranged from 1.38-3.19 mSv depending on scan length and phantom sex. Effective dose for half rotation thorax scans with offset isocentre varied by almost a factor of three depending on laterality of the isocentre, patient sex and imaged field length. The CBCT imaging doses simulated here reveal large variations in dose depending on imaging isocentre location, patient sex and partial rotation angles. This information may be used to estimate risks from CBCT and to optimize CBCT imaging protocols.
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Affiliation(s)
- T E Marchant
- The University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, M20 4BX, UK. Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, M20 4BX, UK
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Rampado O, Giglioli FR, Rossetti V, Fiandra C, Ragona R, Ropolo R. Evaluation of various approaches for assessing dose indicators and patient organ doses resulting from radiotherapy cone-beam CT. Med Phys 2016; 43:2515. [DOI: 10.1118/1.4947129] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Hess CB, Thompson HM, Benedict SH, Seibert JA, Wong K, Vaughan AT, Chen AM. Exposure Risks Among Children Undergoing Radiation Therapy: Considerations in the Era of Image Guided Radiation Therapy. Int J Radiat Oncol Biol Phys 2016; 94:978-92. [PMID: 27026304 DOI: 10.1016/j.ijrobp.2015.12.372] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 11/30/2015] [Accepted: 12/22/2015] [Indexed: 12/14/2022]
Abstract
Recent improvements in toxicity profiles of pediatric oncology patients are attributable, in part, to advances in the field of radiation oncology such as intensity modulated radiation (IMRT) and proton therapy (IMPT). While IMRT and IMPT deliver highly conformal dose to targeted volumes, they commonly demand the addition of 2- or 3-dimensional imaging for precise positioning--a technique known as image guided radiation therapy (IGRT). In this manuscript we address strategies to further minimize exposure risk in children by reducing effective IGRT dose. Portal X rays and cone beam computed tomography (CBCT) are commonly used to verify patient position during IGRT and, because their relative radiation exposure is far less than the radiation absorbed from therapeutic treatment beams, their sometimes significant contribution to cumulative risk can be easily overlooked. Optimizing the conformality of IMRT/IMPT while simultaneously ignoring IGRT dose may result in organs at risk being exposed to a greater proportion of radiation from IGRT than from therapeutic beams. Over a treatment course, cumulative central-axis CBCT effective dose can approach or supersede the amount of radiation absorbed from a single treatment fraction, a theoretical increase of 3% to 5% in mutagenic risk. In select scenarios, this may result in the underprediction of acute and late toxicity risk (such as azoospermia, ovarian dysfunction, or increased lifetime mutagenic risk) in radiation-sensitive organs and patients. Although dependent on variables such as patient age, gender, weight, body habitus, anatomic location, and dose-toxicity thresholds, modifying IGRT use and acquisition parameters such as frequency, imaging modality, beam energy, current, voltage, rotational degree, collimation, field size, reconstruction algorithm, and documentation can reduce exposure, avoid unnecessary toxicity, and achieve doses as low as reasonably achievable, promoting a culture and practice of "gentle IGRT."
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Affiliation(s)
- Clayton B Hess
- Department of Radiation Oncology, University California Davis Comprehensive Cancer Center, Sacramento, California
| | - Holly M Thompson
- Department of Diagnostic Radiology, University of California Davis Medical Center, Sacramento, California
| | - Stanley H Benedict
- Department of Radiation Oncology, University California Davis Comprehensive Cancer Center, Sacramento, California
| | - J Anthony Seibert
- Department of Diagnostic Radiology, University of California Davis Medical Center, Sacramento, California
| | - Kenneth Wong
- Department of Radiation Oncology, University of California Los Angeles Jonsson Comprehensive Cancer Center, University of California David Geffen School of Medicine, Los Angeles, California
| | - Andrew T Vaughan
- Department of Radiation Oncology, University California Davis Comprehensive Cancer Center, Sacramento, California
| | - Allen M Chen
- Department of Radiation Oncology, University of California Los Angeles Jonsson Comprehensive Cancer Center, University of California David Geffen School of Medicine, Los Angeles, California.
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Ye JC, Qureshi MM, Clancy P, Dise LN, Willins J, Hirsch AE. Daily patient setup error in prostate image guided radiation therapy with fiducial-based kilovoltage onboard imaging and conebeam computed tomography. Quant Imaging Med Surg 2015; 5:665-72. [PMID: 26682136 DOI: 10.3978/j.issn.2223-4292.2015.10.01] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND This study examined the interfraction setup error in patients undergoing prostate radiotherapy using fiducial markers and on-board imaging. METHODS Patients (n=53) were aligned to the treatment isocenter by laser followed by orthogonal kilovoltage (kV) radiographs to visualize bony anatomy and implanted fiducial markers. The magnitude and direction of couch shifts for isocenter correction required was determined by image registration for bony anatomy and fiducial markers. Twice weekly, 25 of the 53 patients also underwent conebeam computed tomography (CBCT) to measure any residual error in patient positioning. Based on individual coordinate shifts from CBCT, a net three-dimensional (3D) residual shift magnitude vector R was calculated. RESULTS The average couch shifts were 0.26 and 0.40 cm in inferior direction and 0.25 and 0.33 cm in superior direction for alignments made with bony anatomy and fiducial markers, respectively (P<0.0001). There were no significant differences noted in the vertical or lateral planes between the two image registration methods. In subset of 25 patients, no residual shift from fiducial plain film set up was required with CBCT matching in 66.5%, 52.4% and 57.9% of fractions for longitudinal, vertical and lateral planes, respectively, with majority (79%) of patients having a net residual 3D shifts of <0.3 cm. The use of CBCT increased average treatment time by approximately 6 min compared to kV radiographs alone. CONCLUSIONS The residual setup errors following daily kV image guided localization, as determined by CBCT, were small, which demonstrates high accuracy of kV localization when fiducial markers are present.
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Affiliation(s)
- Jason C Ye
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
| | - Muhammad M Qureshi
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
| | - Pauline Clancy
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
| | - Lauren N Dise
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
| | - John Willins
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
| | - Ariel E Hirsch
- 1 Department of Radiation Oncology, Boston Medical Center and Boston University School of Medicine, Boston, MA 02118, USA ; 2 Department of Radiation Oncology, New York Presbyterian Hospital/Weill Cornell Medical Center, New York, NY 10065, USA
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Kumar AS, Singh IRR, Sharma SD, Ravindran BP. Performance characteristics of mobile MOSFET dosimeter for kilovoltage X-rays used in image guided radiotherapy. J Med Phys 2015; 40:123-8. [PMID: 26500397 PMCID: PMC4594380 DOI: 10.4103/0971-6203.165074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The main objective of this study was to investigate the characteristics of metal oxide semiconductor field effect transistor (MOSFET) dosimeter for kilovoltage (kV) X-ray beams in order to perform the in vivo dosimetry during image guidance in radiotherapy. The performance characteristics of high sensitivity MOSFET dosimeters were investigated for 80, 90, 100, 110, 120, and 125 kV X-ray beams used for imaging in radiotherapy. This study was performed using Clinac 2100 C/D medical electron linear accelerator with on-board imaging and kV cone beam computed tomography system. The characteristics studied in this work include energy dependence, angular dependence, and linearity. The X-ray beam outputs were measured as per American Association of Physicists in Medicine (AAPM) TG 61 recommendations using PTW parallel plate (PP) ionization chamber, which was calibrated in terms of air kerma (Nk) by the National Standard Laboratory. The MOSFET dosimeters were calibrated against the PP ionization chamber for all the kV X-ray beams and the calibration coefficient was found to be 0.11 cGy/mV with a standard deviation of about ±1%. The response of MOSFET was found to be energy independent for the kV X-ray energies used in this study. The response of the MOSFET dosimeter was also found independent of angle of incidence for the gantry angles in the range of 0° to 360° in-air as well as at 3 cm depth in tissue equivalent phantom.
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Affiliation(s)
- A Sathish Kumar
- Department of Radiotherapy, Christian Medical College, Vellore, Tamil Nadu, India
| | - I Rabi Raja Singh
- Department of Radiotherapy, Christian Medical College, Vellore, Tamil Nadu, India
| | - S D Sharma
- Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, CTCRS, Anushaktinagar, Mumbai, India
| | - B Paul Ravindran
- Department of Radiotherapy, Christian Medical College, Vellore, Tamil Nadu, India
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Radiation dose measurements of an on-board imager X-ray unit using optically-stimulated luminescence dosimeters. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 38:665-9. [DOI: 10.1007/s13246-015-0386-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 10/12/2015] [Indexed: 12/11/2022]
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Schneider U, Hälg R, Besserer J. Concept for quantifying the dose from image guided radiotherapy. Radiat Oncol 2015; 10:188. [PMID: 26377196 PMCID: PMC4573474 DOI: 10.1186/s13014-015-0492-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/24/2015] [Indexed: 12/17/2022] Open
Abstract
Background Radiographic image guidance is routinely used for patient positioning in radiotherapy. All radiographic guidance techniques can give a significant radiation dose to the patient. The dose from diagnostic imaging is usually managed by using effective dose minimization. In contrast, image-guided radiotherapy adds the imaging dose to an already high level of therapeutic radiation which cannot be easily managed using effective dose. The purpose of this work is the development of a concept of IGRT dose quantification which allows a comparison of imaging dose with commonly accepted variations of therapeutic dose. Methods It is assumed that dose variations of the treatment beam which are accepted in the spirit of the ALARA convention can also be applied to the additional imaging dose. Therefore we propose three dose categories: Category I: The imaging dose is lower than a 2 % variation of the therapy dose. Category II: The imaging dose is larger than in category I, but lower than the therapy dose variations between different treatment techniques. Category III: The imaging dose is larger than in Category II. For various treatment techniques dose measurements are used to define the dose categories. The imaging devices were categorized according to the measured dose. Results Planar kV-kV imaging is a category I imaging procedure. kV-MV imaging is located at the edge between category I and II and is for increasing fraction size safely a category I imaging technique. MV-MV imaging is for all imaging technologies a category II procedure. MV fan beam CT for localization is a category I technology. Low dose protocols for kV CBCT are located between category I and II and are for increasing fraction size a category I imaging technique. All other investigated Pelvis-CBCT protocols are category II procedures. Fan beam CT scout views are category I technology. Live imaging modalities are category III for conventional fractionation, but category II for stereotactic treatments. Conclusions Dose from radiotherapy imaging can be categorized in terms of generally accepted dose variations of therapy dose. This concept allows the quantification of daily dose from image guided radiotherapy in the spirit of the ALARA convention.
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Affiliation(s)
- Uwe Schneider
- Institute of Physics, Science Faculty, University of Zürich, Zürich, Switzerland. .,Radiotherapy Hirslanden, Witellikerstrasse 40, CH-8032, Zürich, Switzerland.
| | - Roger Hälg
- Institute of Physics, Science Faculty, University of Zürich, Zürich, Switzerland. .,Radiotherapy Hirslanden, Witellikerstrasse 40, CH-8032, Zürich, Switzerland.
| | - Jürgen Besserer
- Institute of Physics, Science Faculty, University of Zürich, Zürich, Switzerland. .,Radiotherapy Hirslanden, Witellikerstrasse 40, CH-8032, Zürich, Switzerland.
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Hioki K, Araki F, Ohno T, Tomiyama Y, Nakaguchi Y. Monte Carlo-calculated patient organ doses from kV-cone beam CT in image-guided radiation therapy. Biomed Phys Eng Express 2015. [DOI: 10.1088/2057-1976/1/2/025203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Alaei P, Spezi E. Imaging dose from cone beam computed tomography in radiation therapy. Phys Med 2015; 31:647-58. [PMID: 26148865 DOI: 10.1016/j.ejmp.2015.06.003] [Citation(s) in RCA: 94] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 05/29/2015] [Accepted: 06/05/2015] [Indexed: 12/26/2022] Open
Abstract
Imaging dose in radiation therapy has traditionally been ignored due to its low magnitude and frequency in comparison to therapeutic dose used to treat patients. The advent of modern, volumetric, imaging modalities, often as an integral part of linear accelerators, has facilitated the implementation of image-guided radiation therapy (IGRT), which is often accomplished by daily imaging of patients. Daily imaging results in additional dose delivered to patient that warrants new attention be given to imaging dose. This review summarizes the imaging dose delivered to patients as the result of cone beam computed tomography (CBCT) imaging performed in radiation therapy using current methods and equipment. This review also summarizes methods to calculate the imaging dose, including the use of Monte Carlo (MC) and treatment planning systems (TPS). Peripheral dose from CBCT imaging, dose reduction methods, the use of effective dose in describing imaging dose, and the measurement of CT dose index (CTDI) in CBCT systems are also reviewed.
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Affiliation(s)
| | - Emiliano Spezi
- School of Engineering, Cardiff University, Cardiff, Wales, UK; Velindre Cancer Centre, Cardiff, Wales, UK
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Rehani MM, Gupta R, Bartling S, Sharp GC, Pauwels R, Berris T, Boone JM. Radiological Protection in Cone Beam Computed Tomography (CBCT). ICRP Publication 129. Ann ICRP 2015; 44:9-127. [PMID: 26116562 DOI: 10.1177/0146645315575485] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The objective of this publication is to provide guidance on radiological protection in the new technology of cone beam computed tomography (CBCT). Publications 87 and 102 dealt with patient dose management in computed tomography (CT) and multi-detector CT. The new applications of CBCT and the associated radiological protection issues are substantially different from those of conventional CT. The perception that CBCT involves lower doses was only true in initial applications. CBCT is now used widely by specialists who have little or no training in radiological protection. This publication provides recommendations on radiation dose management directed at different stakeholders, and covers principles of radiological protection, training, and quality assurance aspects. Advice on appropriate use of CBCT needs to be made widely available. Advice on optimisation of protection when using CBCT equipment needs to be strengthened, particularly with respect to the use of newer features of the equipment. Manufacturers should standardise radiation dose displays on CBCT equipment to assist users in optimisation of protection and comparisons of performance. Additional challenges to radiological protection are introduced when CBCT-capable equipment is used for both fluoroscopy and tomography during the same procedure. Standardised methods need to be established for tracking and reporting of patient radiation doses from these procedures. The recommendations provided in this publication may evolve in the future as CBCT equipment and applications evolve. As with previous ICRP publications, the Commission hopes that imaging professionals, medical physicists, and manufacturers will use the guidelines and recommendations provided in this publication for implementation of the Commission's principle of optimisation of protection of patients and medical workers, with the objective of keeping exposures as low as reasonably achievable, taking into account economic and societal factors, and consistent with achieving the necessary medical outcomes.
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Kapanen M, Laaksomaa M, Tulijoki T, Kellokumpu-Lehtinen PL, Hyödynmaa S. Effects of remedies made in patient setup process on residual setup errors and margins in head and neck cancer radiotherapy based on 2D image guidance. Rep Pract Oncol Radiother 2015; 20:292-8. [PMID: 26109917 PMCID: PMC4477121 DOI: 10.1016/j.rpor.2015.03.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 12/04/2014] [Accepted: 03/09/2015] [Indexed: 12/25/2022] Open
Abstract
AIM Patient setup errors were aimed to be reduced in radiotherapy (RT) of head-and-neck (H&N) cancer. Some remedies in patient setup procedure were proposed for this purpose. BACKGROUND RT of H&N cancer has challenges due to patient rotation and flexible anatomy. Residual position errors occurring in treatment situation and required setup margins were estimated for relevant bony landmarks after the remedies made in setup process and compared with previous results. MATERIALS AND METHODS The formation process for thermoplastic masks was improved. Also image matching was harmonized to the vertebrae in the middle of the target and a 5 mm threshold was introduced for immediate correction of systematic errors of the landmarks. After the remedies, residual position errors of bony landmarks were retrospectively determined from 748 orthogonal X-ray images of 40 H&N cancer patients. The landmarks were the vertebrae C1-2, C5-7, the occiput bone and the mandible. The errors include contributions from patient rotation, flexible anatomy and inter-observer variation in image matching. Setup margins (3D) were calculated with the Van Herk formula. RESULTS Systematic residual errors of the landmarks were reduced maximally by 49.8% (p ≤ 0.05) and the margins by 3.1 mm after the remedies. With daily image guidance the setup margins of the landmarks were within 4.4 mm, but larger margins of 6.4 mm were required for the mandible. CONCLUSIONS Remarkable decrease in the residual errors of the bony landmarks and setup margins were achieved through the remedies made in the setup process. The importance of quality assurance of the setup process was demonstrated.
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Affiliation(s)
- Mika Kapanen
- Department of Oncology, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
- Department of Medical Physics, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
| | - Marko Laaksomaa
- Department of Oncology, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
| | - Tapio Tulijoki
- Department of Oncology, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
| | - Pirkko-Liisa Kellokumpu-Lehtinen
- Department of Oncology, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
- School of Medicine, University of Tampere, Tampere, Finland
| | - Simo Hyödynmaa
- Department of Medical Physics, Tampere University Hospital (TAUH), PO BOX 2000 (Teiskontie 35), FI-33521 Tampere, Finland
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Zhang Y, Wu H, Chen Z, Knisely JPS, Nath R, Feng Z, Bao S, Deng J. Concomitant Imaging Dose and Cancer Risk in Image Guided Thoracic Radiation Therapy. Int J Radiat Oncol Biol Phys 2015; 93:523-31. [PMID: 26460994 DOI: 10.1016/j.ijrobp.2015.06.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 05/27/2015] [Accepted: 06/23/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE Kilovoltage cone beam computed tomography (CT) (kVCBCT) imaging guidance improves the accuracy of radiation therapy but imposes an extra radiation dose to cancer patients. This study aimed to investigate concomitant imaging dose and associated cancer risk in image guided thoracic radiation therapy. METHODS AND MATERIALS The planning CT images and structure sets of 72 patients were converted to CT phantoms whose chest circumferences (Cchest) were calculated retrospectively. A low-dose thorax protocol on a Varian kVCBCT scanner was simulated by a validated Monte Carlo code. Computed doses to organs and cardiac substructures (for 5 selected patients of various dimensions) were regressed as empirical functions of Cchest, and associated cancer risk was calculated using the published models. The exposures to nonthoracic organs in children were also investigated. RESULTS The structural mean doses decreased monotonically with increasing Cchest. For all 72 patients, the median doses to the heart, spinal cord, breasts, lungs, and involved chest were 1.68, 1.33, 1.64, 1.62, and 1.58 cGy/scan, respectively. Nonthoracic organs in children received 0.6 to 2.8 cGy/scan if they were directly irradiated. The mean doses to the descending aorta (1.43 ± 0.68 cGy), left atrium (1.55 ± 0.75 cGy), left ventricle (1.68 ± 0.81 cGy), and right ventricle (1.85 ± 0.84 cGy) were significantly different (P<.05) from the heart mean dose (1.73 ± 0.82 cGy). The blade shielding alleviated the exposure to nonthoracic organs in children by an order of magnitude. CONCLUSIONS As functions of patient size, a series of models for personalized estimation of kVCBCT doses to thoracic organs and cardiac substructures have been proposed. Pediatric patients received much higher doses than did the adults, and some nonthoracic organs could be irradiated unexpectedly by the default scanning protocol. Increased cancer risks and disease adverse events in the thorax were strongly related to higher imaging doses and smaller chest dimensions.
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Affiliation(s)
- Yibao Zhang
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing, China
| | - Hao Wu
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing, China
| | - Zhe Chen
- Department of Therapeutic Radiology, Yale University, New Haven, Connecticut
| | - Jonathan P S Knisely
- Department of Radiation Medicine, Hofstra North Shore-LIJ School of Medicine, Hempstead, New York
| | - Ravinder Nath
- Department of Therapeutic Radiology, Yale University, New Haven, Connecticut
| | - Zhongsu Feng
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education), Department of Radiotherapy, Peking University Cancer Hospital & Institute, Beijing, China
| | - Shanglian Bao
- Beijing Key Laboratory of Medical Physics and Engineering, Peking University, Beijing, China
| | - Jun Deng
- Department of Therapeutic Radiology, Yale University, New Haven, Connecticut.
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Turner A, McGuffin M, Au P. An Investigation of the Feasibility and Utility of a Low-dose Cone-beam Computed Tomography Scan Protocol for Head and Neck Cancer Patients. J Med Imaging Radiat Sci 2015; 46:141-147. [PMID: 31052087 DOI: 10.1016/j.jmir.2014.10.005] [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: 07/08/2014] [Revised: 10/18/2014] [Accepted: 10/22/2014] [Indexed: 11/18/2022]
Abstract
INTRODUCTION Routine use of cone-beam computed tomography (CBCT) scan protocols as part of the image guidance process (image-guided radiation therapy) has become an integral part of the practice of radiation therapists (RTs). Concerns regarding imaging dose as well as increased in-room time for patients led to reluctance among site group members to adopt CBCT for all radical head and neck cancer (HNC) patients at our institution. This investigation set out to assess the feasibility and utility of a revised CBCT scan protocol with the aim of supporting daily CBCT for HNC patients receiving radiation therapy. METHODS The project was performed in three phases. Phase 1 involved the experimental adjustment of CBCT scan protocol parameters in clinical use for HNC patients at our institution. An Elekta Synergy linear accelerator with kilovoltage CBCT capability and a RANDO head phantom were used for scan acquisition procedures. Image registration using bony anatomy was performed on two image sets generated using the current clinical scan protocol (HNS20) and an experimental modified scan protocol (MHNS20). Image registration results were compared by two investigators. Measurements of scan doses using a metal-oxide-semiconductor field-effect transistor and a Unidose meter were performed. Catphan phantom images were acquired using HNS20 and MHNS20 protocols. In phase 2, ten volunteer RTs performed image registration and matching processes on two image sets performed using HNS20 and MHNS20 protocols. RTs were unaware of the scan protocols used for image acquisition. A threshold of 3 mm was set (the current maximum couch shift allowance in the clinical HNC IGRT protocol) to compare the image registration data from HNS20 and MHNS20. In phase 3, after research ethics board approval, 10 HNC patients consented to the study. Two pretreatment CBCT scans were performed: scan 1 was acquired using MHNS20 protocol, and scan 2 was acquired using the HNS20 protocol. A threshold of 2 mm was set to compare the differences in couch shift data resulting from the image registration of the two image sets. Comparison of HNS20 and MHNS20 based on image registration results was performed. RESULTS In phase 1, radiation doses measured by the investigators on the left optical lens using a metal-oxide-semiconductor field-effect transistor and a Unidose meter indicated that the MHNS20 protocol would result in a lower dose to the left optical lens. In phase 2, shifts of the treatment table to achieve the planned isocentre, which were recorded after the image matching process, were within 3 mm in 80% of the RT procedures. In the y-axis (superior/inferior direction), 100% of the procedures were within 3 mm. In the z-axis (anterior/posterior) and x-axis (lateral), 90% of the procedures were within 3 mm. Qualitative data from a questionnaire completed by RTs after the image matching indicated that 50% of the RTs had no preference between the images sets in terms of visibility of structures. Forty percent of RTs had no preference regarding speed of matching or preference for registration between the image sets. When a preference was indicated, the HNS20 scan protocol was chosen by the RTs. In phase 3, couch shift data recorded after each CBCT scan were compared. All results in all three planes for 10 patients included in the study were within the 2-mm threshold. CONCLUSIONS The feasibility and clinical utility of a potential lower-dose CBCT scan protocol has been investigated. The modified protocol (MHNS20) produced image data acceptable within current practice using bony anatomy for registration purposes. The MHNS20 protocol also delivered lower doses to the left optical lens and therefore potentially to other pertinent structures. The actual delivered doses to patients during IGRT procedures using the MHNS20 may be different than those measured during this investigation.
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Affiliation(s)
- Angela Turner
- Department of Radiation Therapy, Odette Cancer Centre, Toronto, Ontario, Canada.
| | - Merrylee McGuffin
- Department of Radiation Therapy, Odette Cancer Centre, Toronto, Ontario, Canada
| | - Philip Au
- Department of Medical Physics, Odette Cancer Centre, Toronto, Ontario, Canada
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Block AM, Luce J, Lin JY, Hoggarth MA, Roeske JC. Planar IGRT dose reduction: A practical approach. Pract Radiat Oncol 2015; 5:e239-e244. [DOI: 10.1016/j.prro.2014.09.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 09/19/2014] [Accepted: 09/22/2014] [Indexed: 11/17/2022]
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