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Myronakis M, Hu YH, Jacobson MW, Williams CL, Berbeco RI. MV-based relative electron density estimation (iMREDe) for MR-LINAC dose calculation. Med Phys 2024; 51:2155-2163. [PMID: 38308857 DOI: 10.1002/mp.16969] [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: 06/27/2023] [Revised: 12/08/2023] [Accepted: 01/21/2024] [Indexed: 02/05/2024] Open
Abstract
BACKGROUND MR-LINAC systems have been increasingly utilized for real-time imaging in adaptive treatments worldwide. Challenges in MR representation of air cavities and subsequent estimation of electron density maps impede planning efficiency and may lead to dose calculation uncertainties. PURPOSE To demonstrate the generation of accurate electron density maps using the primary MV beam with a flat-panel imager. METHODS The ViewRay MRIdian MR-LINAC system was modeled digitally for Monte Carlo simulations. Iron shimming, the magnetic field, and the proposed flat panel detector were included in the model. The effect of the magnetic field on the detector response was investigated. Acquisition of projections over 360 degrees was simulated for digital phantoms of the Catphan 505 phantom and a patient treated for Head and Neck cancer. Shim patterns on the projections were removed and detector noise linearity was assessed. Electron density maps were generated for the digital patient phantom using the flat-panel detector and compared with actual treatment planning CT generated electron density maps of the same patient. RESULTS The effect of the magnetic field on the detector point-spread function (PSF) was found to be substantial for field strengths above 50 mT. Shims correction in the projection images using air normalization and in-painting effectively removed reconstruction artifacts without affecting noise linearity. The relative difference between reconstructed electron density maps from the proposed method and electron density maps generated from the treatment planning CT was 11% on average along all slices included in the iMREDe reconstruction. CONCLUSIONS The proposed iMREDe technique demonstrated the feasibility of generating accurate electron densities for the ViewRay MRIdian MR-LINAC system with a flat-panel imager and the primary MV beam. This work is a step towards reducing the time and effort required for adaptive radiotherapy in the current ViewRay MR-LINAC systems.
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Affiliation(s)
- Marios Myronakis
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Yue-Houng Hu
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew William Jacobson
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher Leigh Williams
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
| | - Ross Isaac Berbeco
- Department of Radiation Oncology, Brigham and Women's Hospital, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA
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Farhadi F, Rajagopal JR, Veziroglu EM, Abdollahi H, Shiri I, Nikpanah M, Morris MA, Zaidi H, Rahmim A, Saboury B. Multi-Scale Temporal Imaging: From Micro- and Meso- to Macro-scale-time Nuclear Medicine. PET Clin 2023; 18:135-148. [DOI: 10.1016/j.cpet.2022.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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3
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Scholey JE, Rajagopal A, Vasquez EG, Sudhyadhom A, Larson PEZ. Generation of synthetic megavoltage CT for MRI-only radiotherapy treatment planning using a 3D deep convolutional neural network. Med Phys 2022; 49:6622-6634. [PMID: 35870154 PMCID: PMC9588542 DOI: 10.1002/mp.15876] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 06/10/2022] [Accepted: 07/01/2022] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Megavoltage computed tomography (MVCT) has been implemented on many radiotherapy treatment machines for on-board anatomical visualization, localization, and adaptive dose calculation. Implementing an MR-only workflow by synthesizing MVCT from magnetic resonance imaging (MRI) would offer numerous advantages for treatment planning and online adaptation. PURPOSE In this work, we sought to synthesize MVCT (sMVCT) datasets from MRI using deep learning to demonstrate the feasibility of MRI-MVCT only treatment planning. METHODS MVCTs and T1-weighted MRIs for 120 patients treated for head-and-neck cancer were retrospectively acquired and co-registered. A deep neural network based on a fully-convolutional 3D U-Net architecture was implemented to map MRI intensity to MVCT HU. Input to the model were volumetric patches generated from paired MRI and MVCT datasets. The U-Net was initialized with random parameters and trained on a mean absolute error (MAE) objective function. Model accuracy was evaluated on 18 withheld test exams. sMVCTs were compared to respective MVCTs. Intensity-modulated volumetric radiotherapy (IMRT) plans were generated on MVCTs of four different disease sites and compared to plans calculated onto corresponding sMVCTs using the gamma metric and dose-volume-histograms (DVHs). RESULTS MAE values between sMVCT and MVCT datasets were 93.3 ± 27.5, 78.2 ± 27.5, and 138.0 ± 43.4 HU for whole body, soft tissue, and bone volumes, respectively. Overall, there was good agreement between sMVCT and MVCT, with bone and air posing the greatest challenges. The retrospective dataset introduced additional deviations due to sinus filling or tumor growth/shrinkage between scans, differences in external contours due to variability in patient positioning, or when immobilization devices were absent from diagnostic MRIs. Dose distributions of IMRT plans evaluated for four test cases showed close agreement between sMVCT and MVCT images when evaluated using DVHs and gamma dose metrics, which averaged to 98.9 ± 1.0% and 96.8 ± 2.6% analyzed at 3%/3 mm and 2%/2 mm, respectively. CONCLUSIONS MVCT datasets can be generated from T1-weighted MRI using a 3D deep convolutional neural network with dose calculation on a sample sMVCT in close agreement with the MVCT. These results demonstrate the feasibility of using MRI-derived sMVCT in an MR-only treatment planning workflow.
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Affiliation(s)
- Jessica E Scholey
- Department of Radiation Oncology, The University of California, San Francisco; San Francisco, CA 94158 USA
| | - Abhejit Rajagopal
- Department of Radiology and Biomedical Imaging, The University of California, San Francisco; San Francisco, CA 94158 USA
| | - Elena Grace Vasquez
- Department of Physics, The University of California, Berkeley; Berkeley, CA 94720 USA
| | - Atchar Sudhyadhom
- Department of Radiation Oncology, Brigham & Women’s Hospital/Dana-Farber Cancer Institute/Harvard Medical School, Boston, MA; 02115 USA
| | - Peder Eric Zufall Larson
- Department of Radiology and Biomedical Imaging, The University of California, San Francisco; San Francisco, CA 94158 USA
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Dosimetric effect of modelling non-homogeneous LINAC couch using cone-beam computed tomography on quality assurance (QA) results. JOURNAL OF RADIOTHERAPY IN PRACTICE 2022. [DOI: 10.1017/s1460396921000716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
Aim:
To evaluate the dosimetric effect of modelling a non-homogeneous couch on patients’ quality assurance (QA) gamma pass rates for intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques.
Materials and Methods:
A non-homogeneous treatment couch (TxT 550 TTM, CIVCO, USA) was imaged using the LINAC mounted cone-beam computer tomography (CBCT) system. Modelling this couch in different situations, including incomplete (homogeneous model), correct model and not defined situations in the treatment planning system (TPS), was performed based on the geometrical and material densities data extracted from the CBCT images. Calculated gamma pass rates between TPS dose calculations and the measurements in a phantom for different couch models were obtained and compared at two gamma criteria (2%-2 mm and 3%-3 mm).
Results:
Comparing TPS calculations for the correct modelled couch and the measurements showed high gamma pass rates for both the IMRT and VMAT techniques (96·5 ± 0·9%, 99·2 ± 0·5% for IMRT in 2%-2 mm and 3%-3 mm criteria; 97·5 ± 0·8%, 99·4 ± 0·5% for VMAT). The overall gamma pass rate of the IMRT plan QAs was reduced by about 2% and 3% on average for incomplete and no couch modelling, respectively. These reductions for VMAT techniques were 2·5% and 4·3%, respectively.
Conclusions:
Non-homogeneous couches have different parts with different attenuations, which can be correctly defined using LINAC CBCT. Modelling of treatment couch has a significant effect on patient QA results for VMAT and IMRT plans, especially in radiation fields/subfield transmitting from the couch. We suggest using LINAC CBCTs as an appropriate device for couch modelling in modulated radiotherapy techniques.
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Alsuhaibani A, Elashwah A, Alkafi A, Constantinescus C, ALzorkany F. Stereotactic Body Radiation Therapy (SBRT) Using CyberKnife in Oligometastatic Cancer Patients; Retrospective Evaluation, Single Institution Experience. J Gastrointest Cancer 2020; 50:879-887. [PMID: 30291546 DOI: 10.1007/s12029-018-0170-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
OBJECTIVES We retrospectively evaluate local control rate at 6 months and 1 year in oligometastatic cancer patients treated with SBRT using CyberKnife. METHODS Total of 21 patients with 24 treatment sites from February 2014 till June 2017 who were treated with SBRT in our institution were included in this study. RESULTS Eleven patients were males, 10 patients were females, median age at diagnosis was 63 years, and colorectal cancer is the most commonly diagnosed cancer in 18 patients. The abdomino-pelvic lymph nodes were the commonest treatment site in 11 (45.8%), average PTV volume of 46.4 cc. All the patients received SBRT with average (BED) of 97 GY, 7 treatment sites received BED of < 100GYgroup 1, and 17 received BED ≥ 100GY group 2. No reported G3 or G4 acute or chronic toxicity. The 6 months and 1 year local control (LC) were 95.8 and 88.2%, respectively. After a median follow-up of 16.8 months, 19(90.5%) patients were alive; among them, local progression was observed in 1 (4.1%) treatment site, while systemic progression in 4 (16.6%), and two (9.5%) patients died; they had both local and systemic failures. The 1-year local PFS rate was 82%. In univariate analysis, PTV volume was significantly correlated with LC rate at 6 months (p = 0.001), while the site of metastasis appeared to significantly correlate with PFS (p = 0.03). CONCLUSION SBRT using CyberKnife is feasible, safe, and effective treatment for oligometastatic sites. Six months and 1 year local control rate is 95.8 and 88.2% respectively in our patients cohort, treatment regimens with higher BED resulting in better 1-year local PFS, although it was not statistically significant. A larger cohort of patients and longer follow up is required for better evaluation.
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Affiliation(s)
- Abdullah Alsuhaibani
- Oncology Center, University Medical City, King Saud University, Riyadh, Saudi Arabia.
| | - Ahmed Elashwah
- Radiation oncology department King Faisal specialized hospital and research center, Riyadh, Saudi Arabia
- Kasr Aleini center of clinical oncology and nuclear medicine (NEMROCK), Cairo University, Cairo, Egypt
| | - Abdullah Alkafi
- Radiation oncology department King Faisal specialized hospital and research center, Riyadh, Saudi Arabia
| | - Camelia Constantinescus
- Radiation oncology department King Faisal specialized hospital and research center, Riyadh, Saudi Arabia
| | - Faisal ALzorkany
- Radiation oncology department King Faisal specialized hospital and research center, Riyadh, Saudi Arabia
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Green OL, Henke LE, Hugo GD. Practical Clinical Workflows for Online and Offline Adaptive Radiation Therapy. Semin Radiat Oncol 2019; 29:219-227. [PMID: 31027639 DOI: 10.1016/j.semradonc.2019.02.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Adaptive radiotherapy emerged over 20 years ago and is now an established clinical practice in a number of organ sites. No one solution for adaptive therapy exists. Rather, adaptive radiotherapy is a process which combines multiple tools for imaging, assessment of need for adaptation, treatment planning, and quality assurance of this process. Workflow is therefore a critical aspect to ensure safe, effective, and efficient implementation of adaptive radiotherapy. In this work, we discuss the tools for online and offline adaptive radiotherapy and introduce workflow concepts for these types of adaptive radiotherapy. Common themes and differences between the workflows are introduced and controversies and areas of active research are discussed.
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Affiliation(s)
- Olga L Green
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO
| | - Lauren E Henke
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO
| | - Geoffrey D Hugo
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO.
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Lindsay C, Bazalova‐Carter M, Wang A, Shedlock D, Wu M, Newson M, Xing L, Ansbacher W, Fahrig R, Star‐Lack J. Investigation of combined
kV
/
MV CBCT
imaging with a high‐
DQE MV
detector. Med Phys 2018; 46:563-575. [DOI: 10.1002/mp.13291] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 11/01/2018] [Accepted: 11/02/2018] [Indexed: 01/23/2023] Open
Affiliation(s)
- C. Lindsay
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - M. Bazalova‐Carter
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - A. Wang
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
| | - D. Shedlock
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
| | - M. Wu
- Department of Radiology Stanford University 1201 Welch Rd Stanford CA 94305‐5105 USA
| | - M. Newson
- Department of Physics and Astronomy University of Victoria 3800 Finnerty Rd Victoria BC V8P 5C2 Canada
| | - L. Xing
- Department of Radiation Oncology Stanford University 875 Blake Wilbur Dr Stanford CA 94305‐5847 USA
| | - W. Ansbacher
- Department of Medical Physics BC Cancer Agency ‐ Vancouver Island Centre Victoria BC Canada
| | - R. Fahrig
- Department of Radiology Stanford University 1201 Welch Rd Stanford CA 94305‐5105 USA
| | - J. Star‐Lack
- Varian Medical Systems 3120 Hansen Way Palo Alto CA 94304 USA
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Barateau A, Céleste M, Lafond C, Henry O, Couespel S, Simon A, Acosta O, de Crevoisier R, Périchon N. Calcul de dose de radiothérapie à partir de tomographies coniques : état de l’art. Cancer Radiother 2018; 22:85-100. [PMID: 29276135 DOI: 10.1016/j.canrad.2017.07.050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 06/06/2017] [Accepted: 07/07/2017] [Indexed: 01/26/2023]
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Arns A, Blessing M, Fleckenstein J, Stsepankou D, Boda-Heggemann J, Hesser J, Lohr F, Wenz F, Wertz H. Phantom-based evaluation of dose exposure of ultrafast combined kV-MV-CBCT towards clinical implementation for IGRT of lung cancer. PLoS One 2017; 12:e0187710. [PMID: 29125857 PMCID: PMC5681289 DOI: 10.1371/journal.pone.0187710] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 10/24/2017] [Indexed: 11/19/2022] Open
Abstract
PURPOSE Combined ultrafast 90°+90° kV-MV-CBCT within single breath-hold of 15s has high clinical potential for accelerating imaging for lung cancer patients treated with deep inspiration breath-hold (DIBH). For clinical feasibility of kV-MV-CBCT, dose exposure has to be small compared to prescribed dose. In this study, kV-MV dose output is evaluated and compared to clinically-established kV-CBCT. METHODS Accurate dose calibration was performed for kV and MV energy; beam quality was determined. For direct comparison of MV and kV dose output, relative biological effectiveness (RBE) was considered. CT dose index (CTDI) was determined and measurements in various representative locations of an inhomogeneous thorax phantom were performed to simulate the patient situation. RESULTS A measured dose of 20.5mGE (Gray-equivalent) in the target region was comparable to kV-CBCT (31.2mGy for widely-used, and 9.1mGy for latest available preset), whereas kV-MV spared healthy tissue and reduced dose to 6.6mGE (30%) due to asymmetric dose distribution. The measured weighted CTDI of 12mGE for kV-MV lay in between both clinical presets. CONCLUSIONS Dosimetric properties were in agreement with established imaging techniques, whereas exposure to healthy tissue was reduced. By reducing the imaging time to a single breath-hold of 15s, ultrafast combined kV-MV CBCT shortens patient time at the treatment couch and thus improves patient comfort. It is therefore usable for imaging of hypofractionated lung DIBH patients.
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Affiliation(s)
- Anna Arns
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Manuel Blessing
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Jens Fleckenstein
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dzmitry Stsepankou
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Judit Boda-Heggemann
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Juergen Hesser
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Frank Lohr
- Struttura Complessa di Radioterapia, Dipartimento di Oncologia, Az. Ospedaliero-Universitaria di Modena, Modena, Italy
| | - Frederik Wenz
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Hansjoerg Wertz
- Department of Radiation Oncology, Universitaetsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Ahmed KA, Torres-Roca JF. Stereotactic Body Radiotherapy in the Management of Oligometastatic Disease. Cancer Control 2016; 23:21-9. [PMID: 27009453 DOI: 10.1177/107327481602300105] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The treatment of oligometastatic disease has become common as imaging techniques have advanced and the management of systemic disease has improved. Use of highly targeted, hypofractionated regimens of stereotactic body radiotherapy (SBRT) is now a primary management option for patients with oligometastatic disease. METHODS The properties of SBRT are summarized and the results of retrospective and prospective studies of SBRT use in the management of oligometastases are reviewed. Future directions of SBRT, including optimizing dose and fractionation schedules, are also discussed. RESULTS SBRT can deliver highly conformal, dosed radiation treatments for ablative tumors in a few treatment sessions. Phase 1/2 trials and retrospective institutional results support use of SBRT as a treatment option for oligometastatic disease metastasized to the lung, liver, and spine, and SBRT offers adequate toxicity profiles with good rates of local control. Future directions will involve optimizing dose and fractionation schedules for select histologies to improve rates of local control while limiting toxicity to normal structures. CONCLUSIONS SBRT offers an excellent management option for patients with oligometastases. However, additional research is still needed to optimize dose and fractionation schedules.
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Abstract
Potential ionising radiation exposure scenarios are varied, but all bring risks beyond the simple issues of short-term survival. Whether accidentally exposed to a single, whole-body dose in an act of terrorism or purposefully exposed to fractionated doses as part of a therapeutic regimen, radiation exposure carries the consequence of elevated cancer risk. The long-term impact of both intentional and unintentional exposure could potentially be mitigated by treatments specifically developed to limit the mutations and precancerous replication that ensue in the wake of irradiation The development of such agents would undoubtedly require a substantial degree of in vitro testing, but in order to accurately recapitulate the complex process of radiation-induced carcinogenesis, well-understood animal models are necessary. Inbred strains of the laboratory mouse, Mus musculus, present the most logical choice due to the high number of molecular and physiological similarities they share with humans. Their small size, high rate of breeding and fully sequenced genome further increase its value for use in cancer research. This chapter will review relevant m. musculus inbred and F1 hybrid animals of radiation-induced myeloid leukemia, thymic lymphoma, breast and lung cancers. Method of cancer induction and associated molecular pathologies will also be described for each model.
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12
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Van De Voorde L, Larue R, Persoon L, Öllers M, Nijsten S, Bosmans G, Berbée M, Swinnen A, van Elmpt W, Vanneste B, Verhaegen F, Lambin P. The influence of gastric filling instructions on dose delivery in patients with oesophageal cancer: A prospective study. Radiother Oncol 2015; 117:442-7. [DOI: 10.1016/j.radonc.2015.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 08/28/2015] [Accepted: 09/06/2015] [Indexed: 12/14/2022]
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13
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Held M, Sneed PK, Fogh SE, Pouliot J, Morin O. Feasibility of MV CBCT-based treatment planning for urgent radiation therapy: dosimetric accuracy of MV CBCT-based dose calculations. J Appl Clin Med Phys 2015; 16:458-471. [PMID: 26699575 PMCID: PMC5690985 DOI: 10.1120/jacmp.v16i6.5625] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Revised: 08/18/2015] [Accepted: 08/25/2015] [Indexed: 11/23/2022] Open
Abstract
Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image‐based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit–to–density calibration curves for regular and extended field‐of‐view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole‐brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT‐based dose planning and delivery approach was feasible and time‐efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all treatment sites. PACS numbers: 87.55.D‐, 87.57.Q‐
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14
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Rigaud B, Simon A, Castelli J, Gobeli M, Ospina Arango JD, Cazoulat G, Henry O, Haigron P, De Crevoisier R. Evaluation of deformable image registration methods for dose monitoring in head and neck radiotherapy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:726268. [PMID: 25759821 PMCID: PMC4339705 DOI: 10.1155/2015/726268] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 01/16/2015] [Accepted: 01/16/2015] [Indexed: 11/18/2022]
Abstract
In the context of head and neck cancer (HNC) adaptive radiation therapy (ART), the two purposes of the study were to compare the performance of multiple deformable image registration (DIR) methods and to quantify their impact for dose accumulation, in healthy structures. Fifteen HNC patients had a planning computed tomography (CT0) and weekly CTs during the 7 weeks of intensity-modulated radiation therapy (IMRT). Ten DIR approaches using different registration methods (demons or B-spline free form deformation (FFD)), preprocessing, and similarity metrics were tested. Two observers identified 14 landmarks (LM) on each CT-scan to compute LM registration error. The cumulated doses estimated by each method were compared. The two most effective DIR methods were the demons and the FFD, with both the mutual information (MI) metric and the filtered CTs. The corresponding LM registration accuracy (precision) was 2.44 mm (1.30 mm) and 2.54 mm (1.33 mm), respectively. The corresponding LM estimated cumulated dose accuracy (dose precision) was 0.85 Gy (0.93 Gy) and 0.88 Gy (0.95 Gy), respectively. The mean uncertainty (difference between maximal and minimal dose considering all the 10 methods) to estimate the cumulated mean dose to the parotid gland (PG) was 4.03 Gy (SD = 2.27 Gy, range: 1.06-8.91 Gy).
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Affiliation(s)
- Bastien Rigaud
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
| | - Antoine Simon
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
| | - Joël Castelli
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
- Centre Eugene Marquis, Radiotherapy Department, 35000 Rennes, France
| | - Maxime Gobeli
- Centre Eugene Marquis, Radiotherapy Department, 35000 Rennes, France
| | - Juan-David Ospina Arango
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
| | - Guillaume Cazoulat
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
| | - Olivier Henry
- Centre Eugene Marquis, Radiotherapy Department, 35000 Rennes, France
| | - Pascal Haigron
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
| | - Renaud De Crevoisier
- Université de Rennes 1, LTSI, Campus de Beaulieu, 35000 Rennes, France
- INSERM, U1099, Campus de Beaulieu, 35000 Rennes, France
- Centre Eugene Marquis, Radiotherapy Department, 35000 Rennes, France
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Kanakavelu N, Samuel EJJ. Assessment and evaluation of MV image guidance system performance in radiotherapy. Rep Pract Oncol Radiother 2015; 20:188-97. [PMID: 25949222 DOI: 10.1016/j.rpor.2015.01.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/19/2014] [Accepted: 01/15/2015] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND AND AIM The clinical use of imaging system in image guided radiotherapy (IGRT) necessitates performing periodic quality assurance of the system to be confident in applying corrections for patient set-up errors. We aim to develop and implement a quality assurance (QA) programme for megavoltage (MV) based image guidance system and assess its long term performance for a period of 3 years. MATERIALS AND METHODS Periodic QA tests were performed for the MV planar and cone beam computed tomography (CBCT) imaging system to assess the system safety, mechanical and geometrical accuracy, image quality and dose. The tests were performed using the equipment supplied by the manufacturer along with the image guidance system and using simple methods developed in-house. The test results were compared with expected or baseline values established during commissioning. RESULTS The safety system was found to be functional. The results of mechanical and geometrical tests were in good agreement with the expected results. The system mechanical positioning was stable and reproducible within ±2 mm accuracy. The image quality and the imaging dose of the planar and CBCT imaging were found to agree with the baseline values and the manufacturer specifications. DISCUSSION Throughout the three-year period, all the QA tests were within the specification. The mechanical and geometrical tests are most crucial as they directly affect the patient positioning accuracy. CONCLUSION We conclude that the MV image guidance system is efficient to perform IGRT and insist to perform periodic QA tests and calibration for the system.
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Affiliation(s)
- Nithya Kanakavelu
- Department of Radiation Oncology, Medwin Cancer Center, Hyderabad, India ; Photonics, Nuclear and Medical Physics Division, VIT University, Vellore, India
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Srinivasan K, Mohammadi M, Shepherd J. Applications of linac-mounted kilovoltage Cone-beam Computed Tomography in modern radiation therapy: A review. Pol J Radiol 2014; 79:181-93. [PMID: 25006356 PMCID: PMC4085117 DOI: 10.12659/pjr.890745] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 03/27/2014] [Indexed: 11/23/2022] Open
Abstract
The use of Cone-beam Computed Tomography (CBCT) in radiotherapy is increasing due to the widespread implementation of kilovoltage systems on the currently available linear accelerators. Cone beam CT acts as an effective Image-Guided Radiotherapy (IGRT) tool for the verification of patient position. It also opens up the possibility of real-time re-optimization of treatment plans for Adaptive Radiotherapy (ART). This paper reviews the most prominent applications of CBCT (linac-mounted) in radiation therapy, focusing on CBCT-based planning and dose calculation studies. This is followed by a concise review of the main issues associated with CBCT, such as imaging artifacts, dose and image quality. It explores how medical physicists and oncologists can best apply CBCT for therapeutic applications.
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Affiliation(s)
- Kavitha Srinivasan
- School of Chemistry and Physics, University of Adelaide, Adelaide, Australia
| | - Mohammad Mohammadi
- School of Chemistry and Physics, University of Adelaide, Adelaide, Australia ; Department of Medical Physics, Royal Adelaide Hospital, Adelaide, Australia
| | - Justin Shepherd
- Department of Medical Physics, Royal Adelaide Hospital, Adelaide, Australia
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17
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Cazoulat G, Simon A, Dumenil A, Gnep K, De Crevoisier R, Acosta-Tamayo O, Haigron P. Surface-constrained nonrigid registration for dose monitoring in prostate cancer radiotherapy. IEEE TRANSACTIONS ON MEDICAL IMAGING 2014; 33:1464-1474. [PMID: 24710827 PMCID: PMC5325876 DOI: 10.1109/tmi.2014.2314574] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This paper addresses the issue of cumulative dose estimation from cone beam computed tomography (CBCT) images in prostate cancer radiotherapy. It focuses on the dose received by the surfaces of the main organs at risk, namely the bladder and rectum. We have proposed both a surface-constrained dose accumulation approach and its extensive evaluation. Our approach relied on the nonrigid registration (NRR) of daily acquired CBCT images on the planning CT image. This proposed NRR method was based on a Demons-like algorithm, implemented in combination with mutual information metric. It allowed for different levels of geometrical constraints to be considered, ensuring a better point to point correspondence, especially when large deformations occurred, or in high dose gradient areas. The three following implementations: 1) full iconic NRR; 2) iconic NRR constrained with landmarks (LCNRR); 3) NRR constrained with full delineation of organs (DBNRR). To obtain reference data, we designed a numerical phantom based on finite-element modeling and image simulation. The methods were assessed on both the numerical phantom and real patient data in order to quantify uncertainties in terms of dose accumulation. The LCNRR method appeared to constitute a good compromise for dose monitoring in clinical practice.
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Affiliation(s)
- Guillaume Cazoulat
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
| | - Antoine Simon
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
| | - Aurelien Dumenil
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
| | - Khemara Gnep
- Centre Eugène Marquis
CRLCC Eugène Marquis - Avenue Bataille Flandres-Dunkerque 35042 RENNES CEDEX
| | - Renaud De Crevoisier
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
- Centre Eugène Marquis
CRLCC Eugène Marquis - Avenue Bataille Flandres-Dunkerque 35042 RENNES CEDEX
| | - Oascar Acosta-Tamayo
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
| | - Pascal Haigron
- LTSI, Laboratoire Traitement du Signal et de l'Image
Institut National de la Santé et de la Recherche Médicale - U1099Université de Rennes 1 - Campus Universitaire de Beaulieu - Bât 22 - 35042 Rennes
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Markwell T, Perera L, Trapp J, Fielding A. Evaluation of MegaVoltage Cone Beam CT image quality with an unmodified Elekta Precise Linac and EPID: a feasibility study. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2014; 37:291-302. [DOI: 10.1007/s13246-014-0258-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 02/26/2014] [Indexed: 11/30/2022]
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19
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Liu Y, Chan TCY, Lee CG, Cho YB, Islam MK. A stochastic model for tumor geometry evolution during radiation therapy in cervical cancer. Med Phys 2014; 41:021705. [PMID: 24506596 DOI: 10.1118/1.4859355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To develop mathematical models to predict the evolution of tumor geometry in cervical cancer undergoing radiation therapy. METHODS The authors develop two mathematical models to estimate tumor geometry change: a Markov model and an isomorphic shrinkage model. The Markov model describes tumor evolution by investigating the change in state (either tumor or nontumor) of voxels on the tumor surface. It assumes that the evolution follows a Markov process. Transition probabilities are obtained using maximum likelihood estimation and depend on the states of neighboring voxels. The isomorphic shrinkage model describes tumor shrinkage or growth in terms of layers of voxels on the tumor surface, instead of modeling individual voxels. The two proposed models were applied to data from 29 cervical cancer patients treated at Princess Margaret Cancer Centre and then compared to a constant volume approach. Model performance was measured using sensitivity and specificity. RESULTS The Markov model outperformed both the isomorphic shrinkage and constant volume models in terms of the trade-off between sensitivity (target coverage) and specificity (normal tissue sparing). Generally, the Markov model achieved a few percentage points in improvement in either sensitivity or specificity compared to the other models. The isomorphic shrinkage model was comparable to the Markov approach under certain parameter settings. Convex tumor shapes were easier to predict. CONCLUSIONS By modeling tumor geometry change at the voxel level using a probabilistic model, improvements in target coverage and normal tissue sparing are possible. Our Markov model is flexible and has tunable parameters to adjust model performance to meet a range of criteria. Such a model may support the development of an adaptive paradigm for radiation therapy of cervical cancer.
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Affiliation(s)
- Yifang Liu
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada
| | - Timothy C Y Chan
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada and Techna Institute for the Advancement of Technology for Health, 124-100 College Street Toronto, Ontario M5G 1P5, Canada
| | - Chi-Guhn Lee
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario M5S 3G8, Canada
| | - Young-Bin Cho
- Department of Radiation Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 610 University of Avenue, Toronto, Ontario M5T 2M9, Canada and Department of Radiation Oncology, University of Toronto, 148-150 College Street, Toronto, Ontario M5S 3S2, Canada
| | - Mohammad K Islam
- Department of Radiation Physics, Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, 610 University of Avenue, Toronto, Ontario M5T 2M9, Canada; Department of Radiation Oncology, University of Toronto, 148-150 College Street, Toronto, Ontario M5S 3S2, Canada; and Techna Institute for the Advancement of Technology for Health, 124-100 College Street, Toronto, Ontario M5G 1P5, Canada
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20
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Oh S, Stewart J, Moseley J, Kelly V, Lim K, Xie J, Fyles A, Brock KK, Lundin A, Rehbinder H, Milosevic M, Jaffray D, Cho YB. Hybrid adaptive radiotherapy with on-line MRI in cervix cancer IMRT. Radiother Oncol 2014; 110:323-8. [DOI: 10.1016/j.radonc.2013.11.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 11/05/2013] [Accepted: 11/09/2013] [Indexed: 10/25/2022]
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21
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Matsubara K, Kohno R, Nishioka S, Shibuya T, Ariji T, Akimoto T, Saitoh H. Experimental evaluation of actual delivered dose using mega-voltage cone-beam CT and direct point dose measurement. Med Dosim 2013; 38:153-9. [DOI: 10.1016/j.meddos.2012.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 08/23/2012] [Accepted: 10/25/2012] [Indexed: 11/17/2022]
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22
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De Los Santos J, Popple R, Agazaryan N, Bayouth JE, Bissonnette JP, Bucci MK, Dieterich S, Dong L, Forster KM, Indelicato D, Langen K, Lehmann J, Mayr N, Parsai I, Salter W, Tomblyn M, Yuh WTC, Chetty IJ. Image guided radiation therapy (IGRT) technologies for radiation therapy localization and delivery. Int J Radiat Oncol Biol Phys 2013; 87:33-45. [PMID: 23664076 DOI: 10.1016/j.ijrobp.2013.02.021] [Citation(s) in RCA: 92] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 02/14/2013] [Accepted: 02/16/2013] [Indexed: 12/27/2022]
Affiliation(s)
- Jennifer De Los Santos
- Department of Radiation Oncology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
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Cho BC, Huh HD, Kim JS, Choi JH, Kim SH, Cho KH, Cho SJ, Min CK, Shin DO, Lee SH, Park DW, Kim KB, Choi SH, Kim HY, Ahn WS, Kim TH, Han SC. Guideline for Imaging Dose on Image-Guided Radiation Therapy. ACTA ACUST UNITED AC 2013. [DOI: 10.14316/pmp.2013.24.1.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Byung Chul Cho
- Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Hyun Do Huh
- Department of Radiation Oncology, Inha Univeristy Hospital, Incheon, Korea
| | - Jin Sung Kim
- Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jin Ho Choi
- Department of Radiation Oncology, College of Medicine, Gachon University Gil Hospital, Incheon, Korea
| | - Seong Hoon Kim
- Department of Radiation Oncology, Hanyang University Hospital, Seoul, Korea
| | - Kwang Hwan Cho
- Department of Radiation Oncology, Soonchunhyang University Hospital, College of Medicine, Asan, Korea
| | - Sam Ju Cho
- Department of Radiological Science, College of Health Science, Eulji University, Seongnam, Korea
| | - Chul Kee Min
- Department of Radiation Oncology, Soonchunhyang University Hospital, College of Medicine, Asan, Korea
| | - Dong Oh Shin
- Department of Radiation Oncology, College of Medicine, Kyung Hee University Medical Center, Suwon, Korea
| | - Sang Hoon Lee
- Department of Radiation Oncology, Cheil General Hospital & Women's Healthcare Center, Kwandong University College of Medicine, Seoul, Korea
| | - Dong Wook Park
- Department of Radiation Oncology, Inje University Hospital, Seoul, Korea
| | - Kum Bae Kim
- Research Center for Radiotherapy, Korea Institute of Radiological & Medical Sciences, Seoul, Korea
| | - Sang Hyoun Choi
- Department of Radiation Oncology, Inha Univeristy Hospital, Incheon, Korea
| | - Hye Young Kim
- Department of Radiation Oncology, Inha Univeristy Hospital, Incheon, Korea
| | - Woo-sang Ahn
- Department of Radiation Oncology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
| | - Tae Hyeong Kim
- Research Center for Radiotherapy, Korea Institute of Radiological & Medical Sciences, Seoul, Korea
| | - Su Cheol Han
- Research Center for Radiotherapy, Korea Institute of Radiological & Medical Sciences, Seoul, Korea
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24
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Hughes J, Holloway LC, Quinn A, Fielding A. An investigation into factors affecting electron density calibration for a megavoltage cone-beam CT system. J Appl Clin Med Phys 2012; 13:3271. [PMID: 22955638 PMCID: PMC5718240 DOI: 10.1120/jacmp.v13i5.3271] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 04/23/2012] [Accepted: 06/03/2012] [Indexed: 11/23/2022] Open
Abstract
There is a growing interest in the use of megavoltage cone-beam computed tomography (MV CBCT) data for radiotherapy treatment planning. To calculate accurate dose distributions, knowledge of the electron density (ED) of the tissues being irradiated is required. In the case of MV CBCT, it is necessary to determine a calibration-relating CT number to ED, utilizing the photon beam produced for MV CBCT. A number of different parameters can affect this calibration. This study was undertaken on the Siemens MV CBCT system, MVision, to evaluate the effect of the following parameters on the reconstructed CT pixel value to ED calibration: the number of monitor units (MUs) used (5, 8, 15 and 60 MUs), the image reconstruction filter (head and neck, and pelvis), reconstruction matrix size (256 by 256 and 512 by 512), and the addition of extra solid water surrounding the ED phantom. A Gammex electron density CT phantom containing EDs from 0.292 to 1.707 was imaged under each of these conditions. The linear relationship between MV CBCT pixel value and ED was demonstrated for all MU settings and over the range of EDs. Changes in MU number did not dramatically alter the MV CBCT ED calibration. The use of different reconstruction filters was found to affect the MV CBCT ED calibration, as was the addition of solid water surrounding the phantom. Dose distributions from treatment plans calculated with simulated image data from a 15 MU head and neck reconstruction filter MV CBCT image and a MV CBCT ED calibration curve from the image data parameters and a 15 MU pelvis reconstruction filter showed small and clinically insignificant differences. Thus, the use of a single MV CBCT ED calibration curve is unlikely to result in any clinical differences. However, to ensure minimal uncertainties in dose reporting, MV CBCT ED calibration measurements could be carried out using parameter-specific calibration measurements.
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Affiliation(s)
- Jessica Hughes
- School of Physical and Chemical Science, Queensland University of Technology, Brisbane, Queensland, Australia
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25
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Jia MX, Zhang X, Li N, Wang EY, Liu DW, Cai WS. Peripheral dose from megavoltage cone-beam CT imaging for nasopharyngeal carcinoma image-guided radiation therapy. J Appl Clin Med Phys 2012; 13:3869. [PMID: 22955655 PMCID: PMC5718218 DOI: 10.1120/jacmp.v13i5.3869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2011] [Revised: 04/25/2012] [Accepted: 04/12/2012] [Indexed: 11/23/2022] Open
Abstract
The growing use of cone-beam computed tomography (CBCT) for IGRT has increased concerns over the additional radiation dose to patients. The in-field dose of IGRT and the peripheral dose (PD) from kilovoltage CBCT (KV-CBCT) imaging have been well quantified. The purpose of this work is to evaluate the peripheral dose from megavoltage CBCT (MV-CBCT) imaging for nasopharyngeal carcinoma IGRT, to determine the correlation of peripheral dose with MU protocol and imaging field size, and to estimate out-of-field organ-at-risk (OAR) dose delivered to patients. Measurements of peripheral MV-CBCT doses were made with a 0.65 cm(3) ionization chamber placed inside in a specially designed phantom at various depths and distances from the imaging field edges. The peripheral dose at reference point inside the phantom was measured with the same ionization chamber to investigate the linearity between MUs used for MV-CBCT imaging and the PD. The peripheral surface doses at the anterior, lateral, and posterior of the phantom at various distances from the imaging field edge were also measured with thermoluminescent dosimeters (TLDs). Seven nasopharyngeal carcinoma patients were selected and scanned before treatment with head-neck protocol, and the peripheral surface doses were measured with TLDs placed on the anterior, lateral, and posterior surfaces at the axial plane of 15 cm distance from the field edge. The measured peripheral doses data in the phantom were utilized to estimate the peripheral OAR dose. Peripheral dose from MV-CBCT imaging increased with increasing number of MUs used for imaging protocol and with increasing the imaging field size. The measured peripheral doses in the phantom decreased as distance from the imaging field edges increased. PD also decreased as the depth from the phantom surface increased. For the patient PD measurements, the anterior, lateral, and posterior surface doses of 15 cm distance from the field edge were 2.84 × 10(-2), 1.01 × 10(-2), and 0.78 × 10(-2) cGy/MU, respectively. The lens, thyroid, breast, and ovary and testicle, which are outside the treatment and imaging fields, were estimated to receive peripheral OAR doses from MV-CBCT imaging of 42.4 × 10(-2), 11.9 × 10(-2), 1.4 × 10(-2), 1.0 × 10(-2), and 0.5 × 10(-2) cGy/MU, respectively. In conclusion, MV-CBCT generates a peripheral dose beyond the edge of the MV-CBCT scanning field that is of a similar order of magnitude to the peripheral dose from kV-CBCT imaging. In clinic, using the smallest number of MUs allowable and reducing MV-CBCT scanning field size without compromising acquired image quality is an effective method of reducing the peripheral OAR dose received by patients.
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Affiliation(s)
- Ming X Jia
- Department of Radiation Oncology, Shengjing Hospital of China Medical University, Shenyang, China.
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26
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Lu C, Chelikani S, Jaffray DA, Milosevic MF, Staib LH, Duncan JS. Simultaneous nonrigid registration, segmentation, and tumor detection in MRI guided cervical cancer radiation therapy. IEEE TRANSACTIONS ON MEDICAL IMAGING 2012; 31:1213-27. [PMID: 22328178 PMCID: PMC3889159 DOI: 10.1109/tmi.2012.2186976] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
External beam radiation therapy (EBRT) for the treatment of cancer enables accurate placement of radiation dose on the cancerous region. However, the deformation of soft tissue during the course of treatment, such as in cervical cancer, presents significant challenges for the delineation of the target volume and other structures of interest. Furthermore, the presence and regression of pathologies such as tumors may violate registration constraints and cause registration errors. In this paper, automatic segmentation, nonrigid registration and tumor detection in cervical magnetic resonance (MR) data are addressed simultaneously using a unified Bayesian framework. The proposed novel method can generate a tumor probability map while progressively identifying the boundary of an organ of interest based on the achieved nonrigid transformation. The method is able to handle the challenges of significant tumor regression and its effect on surrounding tissues. The new method was compared to various currently existing algorithms on a set of 36 MR data from six patients, each patient has six T2-weighted MR cervical images. The results show that the proposed approach achieves an accuracy comparable to manual segmentation and it significantly outperforms the existing registration algorithms. In addition, the tumor detection result generated by the proposed method has a high agreement with manual delineation by a qualified clinician.
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Affiliation(s)
- Chao Lu
- Department of Electrical Engineering, School of Engineering and Applied Science, Yale University, New Haven, CT 06520, USA.
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27
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Bissonnette JP, Balter PA, Dong L, Langen KM, Lovelock DM, Miften M, Moseley DJ, Pouliot J, Sonke JJ, Yoo S. Quality assurance for image-guided radiation therapy utilizing CT-based technologies: A report of the AAPM TG-179. Med Phys 2012; 39:1946-63. [PMID: 22482616 DOI: 10.1118/1.3690466] [Citation(s) in RCA: 198] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
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28
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Teymurazyan A, Pang G. Monte Carlo simulation of a novel water-equivalent electronic portal imaging device using plastic scintillating fibers. Med Phys 2012; 39:1518-29. [DOI: 10.1118/1.3687163] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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29
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Sheng K, Jones R, Yang W, Saraiya S, Schneider B, Chen Q, Sobering G, Olivera G, Read P. 3D Dose Verification Using Tomotherapy CT Detector Array. Int J Radiat Oncol Biol Phys 2012; 82:1013-20. [DOI: 10.1016/j.ijrobp.2010.12.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 12/22/2010] [Accepted: 12/29/2010] [Indexed: 11/26/2022]
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30
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Alexander EJ, Harris VA, Sohaib A, Dearnaley D. Reducing the side effects of external beam radiotherapy in prostate cancer: role of imaging techniques. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/iim.11.65] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Chen Q, Westerly D, Fang Z, Sheng K, Chen Y. TomoTherapy MLC verification using exit detector data. Med Phys 2011; 39:143-51. [DOI: 10.1118/1.3666762] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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32
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Thariat J, Aluwini S, Pan Q, Caullery M, Marcy PY, Housset M, Lagrange JL. Image-guided radiation therapy for muscle-invasive bladder cancer. Nat Rev Urol 2011; 9:23-9. [DOI: 10.1038/nrurol.2011.173] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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33
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Breitbach EK, Maltz JS, Gangadharan B, Bani-Hashemi A, Anderson CM, Bhatia SK, Stiles J, Edwards DS, Flynn RT. Image quality improvement in megavoltage cone beam CT using an imaging beam line and a sintered pixelated array system. Med Phys 2011; 38:5969-79. [DOI: 10.1118/1.3651470] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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Dosimetric Evaluation Between Megavoltage Cone-Beam Computed Tomography and Body Mass Index for Intracranial, Thoracic, and Pelvic Localization. Med Dosim 2011; 36:284-91. [DOI: 10.1016/j.meddos.2010.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2010] [Revised: 04/24/2010] [Accepted: 05/10/2010] [Indexed: 11/17/2022]
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35
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Su Z, Zhang L, Ramakrishnan V, Hagan M, Anscher M. Investigations of interference between electromagnetic transponders and wireless MOSFET dosimeters: a phantom study. Med Phys 2011; 38:2450-4. [PMID: 21776780 DOI: 10.1118/1.3578602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To evaluate both the Calypso Systems' (Calypso Medical Technologies, Inc., Seattle, WA) localization accuracy in the presence of wireless metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters of dose verification system (DVS, Sicel Technologies, Inc., Morrisville, NC) and the dosimeters' reading accuracy in the presence of wireless electromagnetic transponders inside a phantom. METHODS A custom-made, solid-water phantom was fabricated with space for transponders and dosimeters. Two inserts were machined with positioning grooves precisely matching the dimensions of the transponders and dosimeters and were arranged in orthogonal and parallel orientations, respectively. To test the transponder localization accuracy with/without presence of dosimeters (hypothesis 1), multivariate analyses were performed on transponder-derived localization data with and without dosimeters at each preset distance to detect statistically significant localization differences between the control and test sets. To test dosimeter dose-reading accuracy with/without presence of transponders (hypothesis 2), an approach of alternating the transponder presence in seven identical fraction dose (100 cGy) deliveries and measurements was implemented. Two-way analysis of variance was performed to examine statistically significant dose-reading differences between the two groups and the different fractions. A relative-dose analysis method was also used to evaluate transponder impact on dose-reading accuracy after dose-fading effect was removed by a second-order polynomial fit. RESULTS Multivariate analysis indicated that hypothesis 1 was false; there was a statistically significant difference between the localization data from the control and test sets. However, the upper and lower bounds of the 95% confidence intervals of the localized positional differences between the control and test sets were less than 0.1 mm, which was significantly smaller than the minimum clinical localization resolution of 0.5 mm. For hypothesis 2, analysis of variance indicated that there was no statistically significant difference between the dosimeter readings with and without the presence of transponders. Both orthogonal and parallel configurations had difference of polynomial-fit dose to measured dose values within 1.75%. CONCLUSIONS The phantom study indicated that the Calypso System's localization accuracy was not affected clinically due to the presence of DVS wireless MOSFET dosimeters and the dosimeter-measured doses were not affected by the presence of transponders. Thus, the same patients could be implanted with both transponders and dosimeters to benefit from improved accuracy of radiotherapy treatments offered by conjunctional use of the two systems.
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Affiliation(s)
- Zhong Su
- Department of Radiation Oncology, University of Florida Proton Therapy Institute, Jacksonville, Florida 32206, USA.
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Lu C, Chelikani S, Papademetris X, Knisely JP, Milosevic MF, Chen Z, Jaffray DA, Staib LH, Duncan JS. An integrated approach to segmentation and nonrigid registration for application in image-guided pelvic radiotherapy. Med Image Anal 2011; 15:772-85. [PMID: 21646038 DOI: 10.1016/j.media.2011.05.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 05/10/2011] [Accepted: 05/11/2011] [Indexed: 11/29/2022]
Abstract
External beam radiotherapy (EBRT) has become the preferred options for nonsurgical treatment of prostate cancer and cervix cancer. In order to deliver higher doses to cancerous regions within these pelvic structures (i.e. prostate or cervix) while maintaining or lowering the doses to surrounding non-cancerous regions, it is critical to account for setup variation, organ motion, anatomical changes due to treatment and intra-fraction motion. In previous work, manual segmentation of the soft tissues is performed and then images are registered based on the manual segmentation. In this paper, we present an integrated automatic approach to multiple organ segmentation and nonrigid constrained registration, which can achieve these two aims simultaneously. The segmentation and registration steps are both formulated using a Bayesian framework, and they constrain each other using an iterative conditional model strategy. We also propose a new strategy to assess cumulative actual dose for this novel integrated algorithm, in order to both determine whether the intended treatment is being delivered and, potentially, whether or not a plan should be adjusted for future treatment fractions. Quantitative results show that the automatic segmentation produced results that have an accuracy comparable to manual segmentation, while the registration part significantly outperforms both rigid and nonrigid registration. Clinical application and evaluation of dose delivery show the superiority of proposed method to the procedure currently used in clinical practice, i.e. manual segmentation followed by rigid registration.
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Affiliation(s)
- Chao Lu
- Department of Electrical Engineering, Yale University, New Haven, CT 06520, USA.
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Sterzing F, Engenhart-Cabillic R, Flentje M, Debus J. Image-guided radiotherapy: a new dimension in radiation oncology. DEUTSCHES ARZTEBLATT INTERNATIONAL 2011; 108:274-80. [PMID: 21603562 DOI: 10.3238/arztebl.2011.0274] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 05/17/2010] [Indexed: 12/21/2022]
Abstract
BACKGROUND The vital importance of imaging techniques in radiation oncology now extends beyond diagnostic evaluation and treatment planning. Recent technical advances have enabled the integration of various imaging modalities into the everyday practice of radiotherapy directly at the linear accelerator, improving the management of inter- and intrafractional variations. METHODS We present the topic of image-guided radiotherapy (IGRT) on the basis of a selective review of the literature. RESULTS IGRT can be performed with the aid of ultrasound, 2D X-ray devices, and computed tomography. It enables instant correction for positioning deviations and thereby improves the precision of daily radiotherapy fractions. It also enables immediate adjustment for changes in the position and filling status of the internal organs. Anatomical changes that take place over the course of radiotherapy, such as weight loss, tumor shrinkage, and the opening of atelectases, can be detected as they occur and accounted for in dosimetric calculations. There have not yet been any randomized controlled trials showing that IGRT causes fewer adverse effects or improves tumor control compared to conventional radiotherapy. CONCLUSION IGRT is more precise and thus potentially safer than conventional radiotherapy. It also enables the application of special radiotherapeutic techniques with narrow safety margins in the vicinity of radiosensitive organs. Proper patient selection for IGRT must take account of the goals of treatment and the planning characteristics, as well as the available technical and human resources. IGRT should be used for steep dose gradients near organs at risk, for highly conformal dose distributions in the gastrointestinal tract where adjustment for filling variations is needed, for high-precision dose escalation to avoid geographic miss, and for patients who cannot lie perfectly still because of pain or claustrophobia.
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Affiliation(s)
- Florian Sterzing
- Abteilung für Radio onkologie und Strahlentherapie, Universitätsklinikum Heidelberg, Germany.
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Chung H, Li J, Samant S. Feasibility of using two-dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry. J Appl Clin Med Phys 2011; 12:3370. [PMID: 21844846 PMCID: PMC5718653 DOI: 10.1120/jacmp.v12i3.3370] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 02/02/2011] [Accepted: 01/25/2011] [Indexed: 11/23/2022] Open
Abstract
Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from -0.2% ~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry.
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Affiliation(s)
- Heeteak Chung
- Department of Nuclear and Radiological Engineering, University of Florida, Gainesville, FL, USA.
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Dose Monitoring in Prostate Cancer Radiotherapy Using CBCT to CT Constrained Elastic Image Registration. LECTURE NOTES IN COMPUTER SCIENCE 2011. [DOI: 10.1007/978-3-642-23944-1_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Yang D, Brame S, El Naqa I, Aditya A, Wu Y, Goddu SM, Mutic S, Deasy JO, Low DA. Technical note: DIRART--A software suite for deformable image registration and adaptive radiotherapy research. Med Phys 2011; 38:67-77. [PMID: 21361176 PMCID: PMC3017581 DOI: 10.1118/1.3521468] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/27/2010] [Accepted: 11/08/2010] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Recent years have witnessed tremendous progress in image guide radiotherapy technology and a growing interest in the possibilities for adapting treatment planning and delivery over the course of treatment. One obstacle faced by the research community has been the lack of a comprehensive open-source software toolkit dedicated for adaptive radiotherapy (ART). To address this need, the authors have developed a software suite called the Deformable Image Registration and Adaptive Radiotherapy Toolkit (DIRART). METHODS DIRART is an open-source toolkit developed in MATLAB. It is designed in an object-oriented style with focus on user-friendliness, features, and flexibility. It contains four classes of DIR algorithms, including the newer inverse consistency algorithms to provide consistent displacement vector field in both directions. It also contains common ART functions, an integrated graphical user interface, a variety of visualization and image-processing features, dose metric analysis functions, and interface routines. These interface routines make DIRART a powerful complement to the Computational Environment for Radiotherapy Research (CERR) and popular image-processing toolkits such as ITK. RESULTS DIRART provides a set of image processing/registration algorithms and postprocessing functions to facilitate the development and testing of DIR algorithms. It also offers a good amount of options for DIR results visualization, evaluation, and validation. CONCLUSIONS By exchanging data with treatment planning systems via DICOM-RT files and CERR, and by bringing image registration algorithms closer to radiotherapy applications, DIRART is potentially a convenient and flexible platform that may facilitate ART and DIR research. 0 2011 Ameri-
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Affiliation(s)
- Deshan Yang
- Department of Radiation Oncology, School of Medicine, Washington University, Saint Louis, Missouri 63110, USA.
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Stauder MC, Miller RC. Stereotactic Body Radiation Therapy (SBRT) for Unresectable Pancreatic Carcinoma. Cancers (Basel) 2010; 2:1565-75. [PMID: 24281173 PMCID: PMC3837322 DOI: 10.3390/cancers2031565] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 08/05/2010] [Accepted: 08/06/2010] [Indexed: 12/13/2022] Open
Abstract
Survival in patients with unresectable pancreatic carcinoma is poor. Studies by Mayo Clinic and the Gastrointestinal Tumor Study Group (GITSG) have established combined modality treatment with chemotherapy and radiation as the standard of care. Use of gemcitabine-based chemotherapy alone has also been shown to provide a benefit, but 5‑year overall survival still remains less than 5%. Conventional radiotherapy is traditionally delivered over a six week period and high toxicity is seen with the concomitant use of chemotherapy. In contrast, SBRT can be delivered in 3–5 days and, when used as a component of combined modality therapy with gemcitabine, disruption to the timely delivery of chemotherapy is minimal. Early single-institution reports of SBRT for unresectable pancreatic carcinoma demonstrate excellent local control with acceptable toxicity. Use of SBRT in unresectable pancreatic carcinoma warrants further investigation in order to improve the survival of patients with historically poor outcomes.
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Lambin P, Petit SF, Aerts HJWL, van Elmpt WJC, Oberije CJG, Starmans MHW, van Stiphout RGPM, van Dongen GAMS, Muylle K, Flamen P, Dekker ALAJ, De Ruysscher D. The ESTRO Breur Lecture 2009. From population to voxel-based radiotherapy: exploiting intra-tumour and intra-organ heterogeneity for advanced treatment of non-small cell lung cancer. Radiother Oncol 2010; 96:145-52. [PMID: 20647155 DOI: 10.1016/j.radonc.2010.07.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Revised: 07/07/2010] [Accepted: 07/07/2010] [Indexed: 01/22/2023]
Abstract
Evidence is accumulating that radiotherapy of non-small cell lung cancer patients can be optimized by escalating the tumour dose until the normal tissue tolerances are met. To further improve the therapeutic ratio between tumour control probability and the risk of normal tissue complications, we firstly need to exploit inter patient variation. This variation arises, e.g. from differences in tumour shape and size, lung function and genetic factors. Secondly improvement is achieved by taking into account intra-tumour and intra-organ heterogeneity derived from molecular and functional imaging. Additional radiation dose must be delivered to those parts of the tumour that need it the most, e.g. because of increased radio-resistance or reduced therapeutic drug uptake, and away from regions inside the lung that are most prone to complication. As the delivery of these treatments plans is very sensitive for geometrical uncertainties, probabilistic treatment planning is needed to generate robust treatment plans. The administration of these complicated dose distributions requires a quality assurance procedure that can evaluate the treatment delivery and, if necessary, adapt the treatment plan during radiotherapy.
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Affiliation(s)
- Philippe Lambin
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, The Netherlands.
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Qian J, Lee L, Liu W, Chu K, Mok E, Luxton G, Le QT, Xing L. Dose reconstruction for volumetric modulated arc therapy (VMAT) using cone-beam CT and dynamic log files. Phys Med Biol 2010; 55:3597-610. [DOI: 10.1088/0031-9155/55/13/002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Petit SF, van Elmpt WJ, Lambin P, Dekker AL. Dose recalculation in megavoltage cone-beam CT for treatment evaluation: Removal of cupping and truncation artefacts in scans of the thorax and abdomen. Radiother Oncol 2010; 94:359-66. [DOI: 10.1016/j.radonc.2009.12.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 12/02/2009] [Accepted: 12/06/2009] [Indexed: 11/30/2022]
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Cheung J, Aubry JF, Yom SS, Gottschalk AR, Celi JC, Pouliot J. Dose Recalculation and the Dose-Guided Radiation Therapy (DGRT) Process Using Megavoltage Cone-Beam CT. Int J Radiat Oncol Biol Phys 2009; 74:583-92. [DOI: 10.1016/j.ijrobp.2008.12.034] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 11/26/2008] [Accepted: 12/19/2008] [Indexed: 10/20/2022]
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van Elmpt W, Nijsten S, Petit S, Mijnheer B, Lambin P, Dekker A. 3D In Vivo Dosimetry Using Megavoltage Cone-Beam CT and EPID Dosimetry. Int J Radiat Oncol Biol Phys 2009; 73:1580-7. [DOI: 10.1016/j.ijrobp.2008.11.051] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2008] [Revised: 11/17/2008] [Accepted: 11/21/2008] [Indexed: 10/21/2022]
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Wang Z, Nelson JW, Yoo S, Wu QJ, Kirkpatrick JP, Marks LB, Yin FF. Refinement of treatment setup and target localization accuracy using three-dimensional cone-beam computed tomography for stereotactic body radiotherapy. Int J Radiat Oncol Biol Phys 2009; 73:571-7. [PMID: 19147021 DOI: 10.1016/j.ijrobp.2008.09.040] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Revised: 09/03/2008] [Accepted: 09/06/2008] [Indexed: 02/07/2023]
Abstract
PURPOSES To quantitatively compare two-dimensional (2D) orthogonal kV with three-dimensional (3D) cone-beam CT (CBCT) for target localization; and to assess intrafraction motion with kV images in patients undergoing stereotactic body radiotherapy (SBRT). METHODS AND MATERIALS A total of 50 patients with 58 lesions received 178 fractions of SBRT. After clinical setup using in-room lasers and skin/cradle marks placed at simulation, patients were imaged and repositioned according to orthogonal kV/MV registration of bony landmarks to digitally reconstructed radiographs from the planning CT. A subsequent CBCT was registered to the planning CT using soft tissue information, and the resultant "residual error" was measured and corrected before treatment. Posttreatment 2D kV and/or 3D CBCT images were compared with pretreatment images to determine any intrafractional position changes. Absolute averages, statistical means, standard deviations, and root mean square (RMS) values of observed setup error were calculated. RESULTS After initial setup to external marks with laser guidance, 2D kV images revealed vector mean setup deviations of 0.67 cm (RMS). Cone-beam CT detected residual setup deviations of 0.41 cm (RMS). Posttreatment imaging demonstrated intrafractional variations of 0.15 cm (RMS). The individual shifts in three standard orthogonal planes showed no obvious directional biases. CONCLUSIONS After localization based on superficial markings in patients undergoing SBRT, orthogonal kV imaging detects setup variations of approximately 3 to 4 mm in each direction. Cone-beam CT detects residual setup variations of approximately 2 to 3 mm.
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Affiliation(s)
- Zhiheng Wang
- Department of Radiation Oncology, Duke University Medical Center, Durham, NC, USA
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Aubry JF, Cheung J, Morin O, Gottschalk A, Beaulieu L, Pouliot J. Correction of megavoltage cone-beam CT images of the pelvic region based on phantom measurements for dose calculation purposes. J Appl Clin Med Phys 2009; 10:33-42. [PMID: 19223832 PMCID: PMC5720499 DOI: 10.1120/jacmp.v10i1.2852] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 07/15/2008] [Accepted: 08/10/2008] [Indexed: 11/23/2022] Open
Abstract
Megavoltage cone‐beam CT (MVCBCT) is an imaging technology that provides a 3D representation of the patient in treatment position. Because it is a form of x‐ray tomography, MVCBCT images give information about the attenuation coefficients of the imaged tissues, and thus could be used for dose calculation. However, the cupping and missing data artifacts seen on MVCBCT images can cause inaccuracies in dose calculations. To eliminate these inaccuracies, a correction method specific to pelvis imaging and based on phantom measurements has been devised. Pelvis‐shaped water phantoms of three different sizes were designed and imaged with MVCBCT. Three sets of correction factors were created from the artifacts observed in these MVCBCT images by dividing the measured CT number by the predefined CT number for water. Linear interpolation is performed between the sets of correction factors to take into account the varying size of different patients. To compensate for the missing anatomy due to the limited field of view of the MVCBCT system, the MVCBCT image is complemented with the kilovoltage CT (kVCT) image acquired for treatment planning. When the correction method is applied to an anthropomorphic pelvis phantom, the standard deviation between dose calculations performed with kVCT and MVCBCT images is 0.6%, with 98% of the dose points agreeing within ±3%. With uncorrected MVCBCT images this percentage falls to 75%. An example of dose calculation performed with a corrected clinical MVCBCT image of a prostate cancer patient shows that changes in anatomy of normal tissues result in variation of the dose distribution received by these tissues. This correction method enables MVCBCT images to be used for the verification of the daily dose distribution for patients treated in the pelvis region. PACS numbers: 87.57.Q‐ Computed tomography, 87.57.cp Artifacts and distortion
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Affiliation(s)
- Jean-François Aubry
- Department of Radiation Oncology, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, U.S.A
| | - Joey Cheung
- Department of Radiation Oncology, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, U.S.A
| | - Olivier Morin
- Department of Radiation Oncology, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, U.S.A
| | - Alexander Gottschalk
- Department of Radiation Oncology, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, U.S.A
| | - Luc Beaulieu
- Département de physique, génie physique et d'optique, Université Laval, Québec, Canada
| | - Jean Pouliot
- Department of Radiation Oncology, UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco, CA, U.S.A
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Steinke MF, Bezak E. Technological approaches to in-room CBCT imaging. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2008; 31:167-79. [PMID: 18946974 DOI: 10.1007/bf03179341] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The use of Cone-Beam Computed Tomography (CBCT) in Image-Guided Radiation Therapy (IGRT) has become increasingly feasible and popular in recent years. Advances and developments in Flat-Panel Imager (FPI) technology and image reconstruction software allow for linac-mounted 3D CBCT imaging. Taking CBCT images on a daily/weekly basis, offers the possibility to guide the treatment beam according to tumour motion and to apply changes to the treatment plan if necessary. This however raises the issue of additional imaging dose and thus increases in secondary cancer risk. The performance characteristics of kV-CBCT and MV-CBCT solutions currently offered by Elekta, Siemens and Varian are compared in this paper in terms of additional imaging dose and image quality. The review also outlines applications of CBCT for IGRT and Adaptive Radiotherapy (ART). As CBCT is not the only in-room IGRT platform, helical MV-CT (Tomotherapy) and in-room CT designs are also presented.
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Affiliation(s)
- M F Steinke
- Department of Physics and Astronomy, University of Heidelberg, Germany.
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van Elmpt W, McDermott L, Nijsten S, Wendling M, Lambin P, Mijnheer B. A literature review of electronic portal imaging for radiotherapy dosimetry. Radiother Oncol 2008; 88:289-309. [PMID: 18706727 DOI: 10.1016/j.radonc.2008.07.008] [Citation(s) in RCA: 306] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2008] [Revised: 07/09/2008] [Accepted: 07/12/2008] [Indexed: 10/21/2022]
Abstract
Electronic portal imaging devices (EPIDs) have been the preferred tools for verification of patient positioning for radiotherapy in recent decades. Since EPID images contain dose information, many groups have investigated their use for radiotherapy dose measurement. With the introduction of the amorphous-silicon EPIDs, the interest in EPID dosimetry has been accelerated because of the favourable characteristics such as fast image acquisition, high resolution, digital format, and potential for in vivo measurements and 3D dose verification. As a result, the number of publications dealing with EPID dosimetry has increased considerably over the past approximately 15 years. The purpose of this paper was to review the information provided in these publications. Information available in the literature included dosimetric characteristics and calibration procedures of various types of EPIDs, strategies to use EPIDs for dose verification, clinical approaches to EPID dosimetry, ranging from point dose to full 3D dose distribution verification, and current clinical experience. Quality control of a linear accelerator, pre-treatment dose verification and in vivo dosimetry using EPIDs are now routinely used in a growing number of clinics. The use of EPIDs for dosimetry purposes has matured and is now a reliable and accurate dose verification method that can be used in a large number of situations. Methods to integrate 3D in vivo dosimetry and image-guided radiotherapy (IGRT) procedures, such as the use of kV or MV cone-beam CT, are under development. It has been shown that EPID dosimetry can play an integral role in the total chain of verification procedures that are implemented in a radiotherapy department. It provides a safety net for simple to advanced treatments, as well as a full account of the dose delivered. Despite these favourable characteristics and the vast range of publications on the subject, there is still a lack of commercially available solutions for EPID dosimetry. As strategies evolve and commercial products become available, EPID dosimetry has the potential to become an accurate and efficient means of large-scale patient-specific IMRT dose verification for any radiotherapy department.
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Affiliation(s)
- Wouter van Elmpt
- Department of Radiation Oncology (MAASTRO), GROW, University Hospital Maastricht, The Netherlands.
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