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Olaciregui-Ruiz I, Rozendaal R, Mijnheer B, Mans A. Site-specific alert criteria to detect patient-related errors with 3D EPID transit dosimetry. Med Phys 2018; 46:45-55. [DOI: 10.1002/mp.13265] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 09/14/2018] [Accepted: 10/19/2018] [Indexed: 01/12/2023] Open
Affiliation(s)
- Igor Olaciregui-Ruiz
- Department of Radiation Oncology; Netherlands Cancer Institute; Plesmanlaan 121 1066 CX Amsterdam The Netherlands
| | - Roel Rozendaal
- Department of Radiation Oncology; Netherlands Cancer Institute; Plesmanlaan 121 1066 CX Amsterdam The Netherlands
| | - Ben Mijnheer
- Department of Radiation Oncology; Netherlands Cancer Institute; Plesmanlaan 121 1066 CX Amsterdam The Netherlands
| | - Anton Mans
- Department of Radiation Oncology; Netherlands Cancer Institute; Plesmanlaan 121 1066 CX Amsterdam The Netherlands
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52
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Rangaraj D, Yaddanapudi S, Cai J. Transmission detectors are safe and the future for patient-specific QA in radiation therapy. Med Phys 2018; 46:1-4. [PMID: 30230548 DOI: 10.1002/mp.13201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 09/11/2018] [Accepted: 09/13/2018] [Indexed: 11/12/2022] Open
Affiliation(s)
| | - Sridhar Yaddanapudi
- Department of Radiation Oncology; University of Iowa Health Care; Iowa City IA 52242 USA
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53
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Mijnheer B, Jomehzadeh A, González P, Olaciregui-Ruiz I, Rozendaal R, Shokrani P, Spreeuw H, Tielenburg R, Mans A. Error detection during VMAT delivery using EPID-based 3D transit dosimetry. Phys Med 2018; 54:137-145. [DOI: 10.1016/j.ejmp.2018.10.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 09/14/2018] [Accepted: 10/02/2018] [Indexed: 11/27/2022] Open
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54
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Najem MA, Tedder M, King D, Bernstein D, Trouncer R, Meehan C, Bidmead AM. In-vivo EPID dosimetry for IMRT and VMAT based on through-air predicted portal dose algorithm. Phys Med 2018; 52:143-153. [PMID: 30139603 DOI: 10.1016/j.ejmp.2018.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 07/02/2018] [Accepted: 07/24/2018] [Indexed: 11/28/2022] Open
Abstract
We have adapted the methodology of Berry et al. (2012) for Intensity Modulated Radiotherapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT) treatments at a fixed source to imager distance (SID) based on the manufacturer's through-air portal dose image prediction algorithm. In order to fix the SID a correction factor was introduced to account for the change in air gap between patient and imager. Commissioning data, collected with multiple field sizes, solid water thicknesses and air gaps, were acquired at 150 cm SID on the Varian aS1200 EPID. The method was verified using six IMRT and seven VMAT plans on up to three different phantoms. The method's sensitivity and accuracy were investigated by introducing errors. A global 3%/3 mm gamma was used to assess the differences between the predicted and measured portal dose images. The effect of a varying air gap on EPID signal was found to be significant - varying by up to 30% with field size, phantom thickness, and air gap. All IMRT plans passed the 3%/3 mm gamma criteria by more than 95% on the three phantoms. 23 of 24 arcs from the VMAT plans passed the 3%/3 mm gamma criteria by more than 95%. This method was found to be sensitive to a range of potential errors. The presented approach provides fast and accurate in-vivo EPID dosimetry for IMRT and VMAT treatments and can potentially replace many pre-treatment verifications.
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Affiliation(s)
- M A Najem
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK.
| | - M Tedder
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London SE1 7EH, UK
| | - D King
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK
| | - D Bernstein
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK
| | - R Trouncer
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK
| | - C Meehan
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK
| | - A M Bidmead
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and The Institute of Cancer Research, Fulham Road, London SW3 6JJ, UK
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55
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Piron O, Varfalvy N, Archambault L. Establishing action threshold for change in patient anatomy using EPID gamma analysis and PTV coverage for head and neck radiotherapy treatment. Med Phys 2018; 45:3534-3545. [PMID: 29896916 DOI: 10.1002/mp.13045] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 05/24/2018] [Accepted: 05/31/2018] [Indexed: 02/28/2024] Open
Abstract
PURPOSE To present a new adaptive radiotherapy (ART) method based on relative gamma analysis and patient classification for the identification of anatomical changes that induce a sufficient dosimetric impact to affect the treatment delivery and require complete replanning. METHODS This retrospective study includes 55 patients treated for a head and neck cancer with IMRT, VMAT, or 3D conformal RT. Electronic Portal Imaging Device images for all treatment fields were acquired daily at every fraction. CBCTs were collected at least once a week. Gamma analysis was performed using the first fraction of the treatment as a reference once validated that it was delivered without error. Gamma analysis parameters (<γ>, standard deviation and the Top 1% γ) were used to define categories using statistic from a k-means clustering analysis. From these categories an action threshold was defined and correlated with dosimetric changes. For 23 of 55 patients, the V100% for PTV was computed for both, the planning CT and original contours deformed onto CBCT acquired at the last fraction. These values were then compared with 2D image relative γ-analysis of EPID images. Sensitivity and specificity of the method for the detection of dosimetric changes were computed. RESULTS Three categories indicating an increasing level of change with the planned treatment were identified. A threshold was established for which patients were at risk of deviation at <γ> = 0.42. From 23 recomputing plans, it has been confirmed that patients with a strong dosimetric impact were above this threshold, with a specificity of 0.80 and a sensitivity of 0.84. CONCLUSIONS The specificity and the sensitivity value confirmed the performance of the method to detect anatomical changes. The γ-analysis threshold correlated well with morphological changes that have a relevant dosimetric impact. Analysis of daily EPID images provides a method to identify patients at risk of deviation from their planned treatment and can support an early replanning decision.
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Affiliation(s)
- Ophélie Piron
- Department de Radio-oncologie, CHU de Quebec, 11 Côte du Palais, Quebec, QC, Canada
- Université Laval, 2325 Rue de l'Université, Ville de Québec, QC, G1V 0A6, Canada
| | - Nicolas Varfalvy
- Department de Radio-oncologie, CHU de Quebec, 11 Côte du Palais, Quebec, QC, Canada
- Université Laval, 2325 Rue de l'Université, Ville de Québec, QC, G1V 0A6, Canada
| | - Louis Archambault
- Department de Radio-oncologie, CHU de Quebec, 11 Côte du Palais, Quebec, QC, Canada
- Université Laval, 2325 Rue de l'Université, Ville de Québec, QC, G1V 0A6, Canada
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56
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Wootton LS, Nyflot MJ, Chaovalitwongse WA, Ford E. Error Detection in Intensity-Modulated Radiation Therapy Quality Assurance Using Radiomic Analysis of Gamma Distributions. Int J Radiat Oncol Biol Phys 2018; 102:219-228. [PMID: 30102197 DOI: 10.1016/j.ijrobp.2018.05.033] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 04/10/2018] [Accepted: 05/13/2018] [Indexed: 10/16/2022]
Abstract
PURPOSE To improve the detection of errors in intensity-modulated radiation therapy (IMRT) with a novel method that uses quantitative image features from radiomics to analyze gamma distributions generated during patient specific quality assurance (QA). METHODS AND MATERIALS One hundred eighty-six IMRT beams from 23 patient treatments were delivered to a phantom and measured with electronic portal imaging device dosimetry. The treatments spanned a range of anatomic sites; half were head and neck treatments, and the other half were drawn from treatments for lung and rectal cancers, sarcoma, and glioblastoma. Planar gamma distributions, or gamma images, were calculated for each beam using the measured dose and calculated doses from the 3-dimensional treatment planning system under various scenarios: a plan without errors and plans with either simulated random or systematic multileaf collimator mispositioning errors. The gamma images were randomly divided into 2 sets: a training set for model development and testing set for validation. Radiomic features were calculated for each gamma image. Error detection models were developed by training logistic regression models on these radiomic features. The models were applied to the testing set to quantify their predictive utility, determined by calculating the area under the curve (AUC) of the receiver operator characteristic curve, and were compared with traditional threshold-based gamma analysis. RESULTS The AUC of the random multileaf collimator mispositioning model on the testing set was 0.761 compared with 0.512 for threshold-based gamma analysis. The AUC for the systematic mispositioning model was 0.717 versus 0.660 for threshold-based gamma analysis. Furthermore, the models could discriminate between the 2 types of errors simulated here, exhibiting AUCs of approximately 0.5 (equivalent to random guessing) when applied to the error they were not designed to detect. CONCLUSIONS The feasibility of error detection in patient-specific IMRT QA using radiomic analysis of QA images has been demonstrated. This methodology represents a substantial step forward for IMRT QA with improved sensitivity and specificity over current QA methods and the potential to distinguish between different types of errors.
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Affiliation(s)
- Landon S Wootton
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, Washington.
| | - Matthew J Nyflot
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, Washington; Department of Radiology, University of Washington School of Medicine, Seattle, Washington
| | - W Art Chaovalitwongse
- Department of Radiology, University of Washington School of Medicine, Seattle, Washington; Department of Industrial Engineering, University of Arkansas, Fayetteville, Arkansas
| | - Eric Ford
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, Washington
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57
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Blake SJ, Cheng Z, McNamara A, Lu M, Vial P, Kuncic Z. A high
DQE
water‐equivalent
EPID
employing an array of plastic‐scintillating fibers for simultaneous imaging and dosimetry in radiotherapy. Med Phys 2018; 45:2154-2168. [DOI: 10.1002/mp.12882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 03/02/2018] [Accepted: 03/11/2018] [Indexed: 12/17/2022] Open
Affiliation(s)
- Samuel J. Blake
- Institute of Medical Physics School of Physics University of Sydney Sydney NSW 2006Australia
- Ingham Institute for Applied Medical Research Sydney NSW 2170Australia
| | - Zhangkai Cheng
- Institute of Medical Physics School of Physics University of Sydney Sydney NSW 2006Australia
- Ingham Institute for Applied Medical Research Sydney NSW 2170Australia
| | - Aimee McNamara
- Department of Radiation Oncology Massachusetts General Hospital Harvard Medical School 30 Fruit St Boston MA 02114USA
| | - Minghui Lu
- Varex Imaging Corporation Santa Clara CA 95054USA
| | - Philip Vial
- Institute of Medical Physics School of Physics University of Sydney Sydney NSW 2006Australia
- Ingham Institute for Applied Medical Research Sydney NSW 2170Australia
- Department of Medical Physics Liverpool and Macarthur Cancer Therapy Centers NSW 2170 Australia
| | - Zdenka Kuncic
- Institute of Medical Physics School of Physics University of Sydney Sydney NSW 2006Australia
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58
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Zhuang AH, Olch AJ. Sensitivity study of an automated system for daily patient QA using EPID exit dose images. J Appl Clin Med Phys 2018; 19:114-124. [PMID: 29508529 PMCID: PMC5978566 DOI: 10.1002/acm2.12303] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 12/08/2017] [Accepted: 01/27/2018] [Indexed: 11/11/2022] Open
Abstract
The dosimetric consequences of errors in patient setup or beam delivery and anatomical changes are not readily known. A new product, PerFRACTION (Sun Nuclear Corporation), is designed to identify these errors by comparing the exit dose image measured on an electronic portal imaging device (EPID) from each field of each fraction to those from baseline fraction images. This work investigates the sensitivity of PerFRACTION to detect the deviation caused by these errors in a variety of realistic scenarios. Integrated EPID images were acquired in clinical mode and saved in ARIA. PerFRACTION automatically pulled the images into its database and performed the user-defined comparison. We induced errors of 1 mm and greater in jaw, multileaf collimator (MLC), and couch position, 1° and greater in collimation rotation (patient yaw), 0.5-1.5% in machine output, rail position, and setup errors of 1-2 mm shifts and 0.5-1° roll rotation. The planning techniques included static, intensity modulated radiation therapy (IMRT) and VMAT fields. Rectangular solid water phantom or anthropomorphic head phantom were used in the beam path in the delivery of some fields. PerFRACTION detected position errors of the jaws, MLC, and couch with an accuracy of better than 0.4 mm, and 0.5° for collimator rotation error and detected the machine output error within 0.2%. The rail position error resulted in PerFRACTION detected dose deviations up to 8% and 3% in open field and VMAT field delivery, respectively. PerFRACTION detected induced errors in IMRT fields within 2.2% of the gamma passing rate using an independent conventional analysis. Using an anthropomorphic phantom, setup errors as small as 1 mm and 0.5° were detected. Our work demonstrates that PerFRACTION, using integrated EPID image, is sensitive enough to identify positional, angular, and dosimetric errors.
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Affiliation(s)
- Audrey H Zhuang
- Department of Radiation Oncology, University of Southern California, Los Angeles, CA, USA
| | - Arthur J Olch
- Department of Radiation Oncology, University of Southern California, Children's Hospital Los Angeles, Los Angeles, CA, USA
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59
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Saito M, Sano N, Shibata Y, Kuriyama K, Komiyama T, Marino K, Aoki S, Ashizawa K, Yoshizawa K, Onishi H. Comparison of MLC error sensitivity of various commercial devices for VMAT pre-treatment quality assurance. J Appl Clin Med Phys 2018; 19:87-93. [PMID: 29500857 PMCID: PMC5978943 DOI: 10.1002/acm2.12288] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 12/04/2017] [Accepted: 01/21/2018] [Indexed: 11/10/2022] Open
Abstract
The purpose of this study was to compare the MLC error sensitivity of various measurement devices for VMAT pre-treatment quality assurance (QA). This study used four QA devices (Scandidos Delta4, PTW 2D-array, iRT systems IQM, and PTW Farmer chamber). Nine retrospective VMAT plans were used and nine MLC error plans were generated for all nine original VMAT plans. The IQM and Farmer chamber were evaluated using the cumulative signal difference between the baseline and error-induced measurements. In addition, to investigate the sensitivity of the Delta4 device and the 2D-array, global gamma analysis (1%/1, 2%/2, and 3%/3 mm), dose difference (1%, 2%, and 3%) were used between the baseline and error-induced measurements. Some deviations of the MLC error sensitivity for the evaluation metrics and MLC error ranges were observed. For the two ionization devices, the sensitivity of the IQM was significantly better than that of the Farmer chamber (P < 0.01) while both devices had good linearly correlation between the cumulative signal difference and the magnitude of MLC errors. The pass rates decreased as the magnitude of the MLC error increased for both Delta4 and 2D-array. However, the small MLC error for small aperture sizes, such as for lung SBRT, could not be detected using the loosest gamma criteria (3%/3 mm). Our results indicate that DD could be more useful than gamma analysis for daily MLC QA, and that a large-area ionization chamber has a greater advantage for detecting systematic MLC error because of the large sensitive volume, while the other devices could not detect this error for some cases with a small range of MLC error.
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Affiliation(s)
- Masahide Saito
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Naoki Sano
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Yuki Shibata
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Kengo Kuriyama
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | | | - Kan Marino
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Shinichi Aoki
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | | | - Kazuya Yoshizawa
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
| | - Hiroshi Onishi
- Department of Radiology, University of Yamanashi, Yamanashi, Japan
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60
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Hillman Y, Kim J, Chetty I, Wen N. Refinement of MLC modeling improves commercial QA dosimetry system for SRS and SBRT patient-specific QA. Med Phys 2018; 45:1351-1359. [DOI: 10.1002/mp.12808] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 01/15/2018] [Accepted: 01/23/2018] [Indexed: 01/17/2023] Open
Affiliation(s)
- Yair Hillman
- Department of Radiation Oncology; Karmanos Cancer Institute at McLaren Macomb; Mt. Clemens MI USA
| | - Josh Kim
- Department of Radiation Oncology; Henry Ford Hospital; Detroit MI USA
| | - Indrin Chetty
- Department of Radiation Oncology; Henry Ford Hospital; Detroit MI USA
| | - Ning Wen
- Department of Radiation Oncology; Henry Ford Hospital; Detroit MI USA
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61
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Setup in a clinical workflow and impact on radiotherapy routine of an in vivo dosimetry procedure with an electronic portal imaging device. PLoS One 2018; 13:e0192686. [PMID: 29432473 PMCID: PMC5809064 DOI: 10.1371/journal.pone.0192686] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 01/29/2018] [Indexed: 12/21/2022] Open
Abstract
High conformal techniques such as intensity-modulated radiation therapy and volumetric-modulated arc therapy are widely used in overloaded radiotherapy departments. In vivo dosimetric screening is essential in this environment to avoid important dosimetric errors. This work examines the feasibility of introducing in vivo dosimetry (IVD) checks in a radiotherapy routine. The causes of dosimetric disagreements between delivered and planned treatments were identified and corrected during the course of treatment. The efficiency of the corrections performed and the added workload needed for the entire procedure were evaluated. The IVD procedure was based on an electronic portal imaging device. A total of 3682 IVD tests were performed for 147 patients who underwent head and neck, abdomen, pelvis, breast, and thorax radiotherapy treatments. Two types of indices were evaluated and used to determine if the IVD tests were within tolerance levels: the ratio R between the reconstructed and planned isocentre doses and a transit dosimetry based on the γ-analysis of the electronic portal images. The causes of test outside tolerance level were investigated and corrected and IVD test was repeated during subsequent fraction. The time needed for each step of the IVD procedure was registered. Pelvis, abdomen, and head and neck treatments had 10% of tests out of tolerance whereas breast and thorax treatments accounted for up to 25%. The patient setup was the main cause of 90% of the IVD tests out of tolerance and the remaining 10% was due to patient morphological changes. An average time of 42 min per day was sufficient to monitor a daily workload of 60 patients in treatment. This work shows that IVD performed with an electronic portal imaging device is feasible in an overloaded department and enables the timely realignment of the treatment quality indices in order to achieve a patient’s final treatment compliant with the one prescribed.
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62
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Held M, Cheung J, Perez Andujar A, Husson F, Morin O. Commissioning and Evaluation of an Electronic Portal Imaging Device-Based In-Vivo Dosimetry Software. Cureus 2018; 10:e2139. [PMID: 29632749 PMCID: PMC5880591 DOI: 10.7759/cureus.2139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This study reports on our experience with the in-vivo dose verification software, EPIgray® (DOSIsoft, Cachan, France). After the initial commissioning process, clinical experiments on phantom treatments were evaluated to assess the level of accuracy of the electronic portal imaging device (EPID) based in-vivo dose verification. EPIgray was commissioned based on the company’s instructions. This involved ion chamber measurements and portal imaging of solid water blocks of various thicknesses between 5 and 35 cm. Field sizes varied between 2 x 2 cm2 and 20 x 20 cm2. The determined conversion factors were adjusted through an additional iterative process using treatment planning system calculations. Subsequently, evaluation was performed using treatment plans of single and opposed beams, as well as intensity modulated radiotherapy (IMRT) plans, based on recommendations from the task group report TG-119 to test for dose reconstruction accuracy. All tests were performed using blocks of solid water slabs as a phantom. For single square fields, the dose at isocenter was reconstructed within 3% accuracy in EPIgray compared to the treatment planning system dose. Similarly, the relative deviation of the total dose was accurately reconstructed within 3% for all IMRT plans with points placed inside a high-dose region near the isocenter. Predictions became less accurate than < 5% when the evaluation point was outside the treatment target. Dose at points 5 cm or more away from the isocenter or within an avoidance structure was reconstructed less reliably. EPIgray formalism accuracy is adequate for an efficient error detection system with verifications performed in high-dose volumes. It provides immediate intra-fractional feedback on the delivery of treatment plans without affecting the treatment beam. Besides the EPID, no additional hardware is required. The software evaluates local point dose measurements to verify treatment plan delivery and patient positioning within 5% accuracy, depending on the placement of evaluation points.
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Affiliation(s)
- Mareike Held
- Radiation Oncology, University of California San Francisco
| | - Joey Cheung
- Radiation Oncology, University of California San Francisco
| | | | | | - Olivier Morin
- Radiation Oncology, University of California San Francisco
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63
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64
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Deshpande S, Blake SJ, Xing A, Metcalfe PE, Holloway LC, Vial P. A simple model for transit dosimetry based on a water equivalent EPID. Med Phys 2018; 45:1266-1275. [DOI: 10.1002/mp.12742] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 11/10/2017] [Accepted: 12/18/2017] [Indexed: 01/20/2023] Open
Affiliation(s)
- S. Deshpande
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2522 Australia
| | - S. J. Blake
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
- School of Physics; Institute of Medical Physics; University of Sydney; Sydney NSW 2006 Australia
| | - A. Xing
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
| | - P. E. Metcalfe
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2522 Australia
| | - L. C. Holloway
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
- Centre for Medical Radiation Physics; University of Wollongong; Wollongong NSW 2522 Australia
- School of Physics; Institute of Medical Physics; University of Sydney; Sydney NSW 2006 Australia
- School of Medicine; South West Sydney Clinical School; University of NSW; Liverpool NSW 2052 Australia
| | - P. Vial
- Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute; Liverpool NSW 2170 Australia
- School of Physics; Institute of Medical Physics; University of Sydney; Sydney NSW 2006 Australia
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65
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Bedford JL, Hanson IM, Hansen VN. Comparison of forward- and back-projection in vivo EPID dosimetry for VMAT treatment of the prostate. Phys Med Biol 2018; 63:025008. [PMID: 29165319 DOI: 10.1088/1361-6560/aa9c60] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In the forward-projection method of portal dosimetry for volumetric modulated arc therapy (VMAT), the integrated signal at the electronic portal imaging device (EPID) is predicted at the time of treatment planning, against which the measured integrated image is compared. In the back-projection method, the measured signal at each gantry angle is back-projected through the patient CT scan to give a measure of total dose to the patient. This study aims to investigate the practical agreement between the two types of EPID dosimetry for prostate radiotherapy. The AutoBeam treatment planning system produced VMAT plans together with corresponding predicted portal images, and a total of 46 sets of gantry-resolved portal images were acquired in 13 patients using an iViewGT portal imager. For the forward-projection method, each acquisition of gantry-resolved images was combined into a single integrated image and compared with the predicted image. For the back-projection method, iViewDose was used to calculate the dose distribution in the patient for comparison with the planned dose. A gamma index for 3% and 3 mm was used for both methods. The results were investigated by delivering the same plans to a phantom and repeating some of the deliveries with deliberately introduced errors. The strongest agreement between forward- and back-projection methods is seen in the isocentric intensity/dose difference, with moderate agreement in the mean gamma. The strongest correlation is observed within a given patient, with less correlation between patients, the latter representing the accuracy of prediction of the two methods. The error study shows that each of the two methods has its own distinct sensitivity to errors, but that overall the response is similar. The forward- and back-projection EPID dosimetry methods show moderate agreement in this series of prostate VMAT patients, indicating that both methods can contribute to the verification of dose delivered to the patient.
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Affiliation(s)
- James L Bedford
- Joint Department of Physics, The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London, SM2 5PT, United Kingdom
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66
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Falco MD, Giancaterino S, De Nicola A, Adorante N, De Lorenzo RG, Di Tommaso M, Vinciguerra A, Trignani M, Perrotti F, Allajbej A, Fidanzio A, Greco F, Grusio M, Genovesi D, Piermattei A. A Feasibility Study for in vivo Dosimetry Procedure in Routine Clinical Practice. Technol Cancer Res Treat 2018; 17:1533033818779201. [PMID: 29871570 PMCID: PMC5992805 DOI: 10.1177/1533033818779201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Purpose: The aim of the in vivo dosimetry, during the fractionated radiation therapy, is the verification of the correct dose delivery to patient. Nowadays, in vivo dosimetry procedures for photon beams are based on the use of the electronic portal imaging device and dedicated software to elaborate electronic portal imaging device images. Methods: In total, 8474 in vivo dosimetry tests were carried out for 386 patients treated with 3-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and volumetric modulated arc therapy techniques, using the SOFTDISO. SOFTDISO is a dedicated software that uses electronic portal imaging device images in order to (1) calculate the R index, that is, the ratio between daily reconstructed dose and the planned one at isocenter and (2) perform a γ-like analysis between the signals, S, of a reference electronic portal imaging device image and that obtained in a daily fraction. It supplies 2 indexes, the percentage γ% of points with γ < 1 and the mean γ value, γmean. In γ-like analysis, the pass criteria for the signals agreement ΔS% and distance to agreement Δd have been selected based on the clinical experience and technology used. The adopted tolerance levels for the 3 indexes were fixed in 0.95 ≤ R ≤ 1.05, γ% ≥ 90%, and γmean ≤ 0.5. Results: The results of R ratio, γ-like, and a visual inspection of these data reported on a monitor screen permitted to individuate 2 classes of errors (1) class 1 that included errors due to inadequate standard quality controls and (2) class 2, due to patient morphological changes. Depending on the technique and anatomical site, a maximum of 18% of tests had at least 1 index out of tolerance; once removed the causes of class-1 errors, almost all patients (except patients with 4 lung and 2 breast cancer treated with 3-dimensional conformal radiotherapy) presented mean indexes values (R¯, γ¯%, and γ¯mean
) within tolerance at the end of treatment course. Class-2 errors were found in some patients. Conclusions: The in vivo dosimetry procedure with SOFTDISO resulted easily implementable, able to individuate errors with a limited workload.
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Affiliation(s)
- Maria D Falco
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Stefano Giancaterino
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Andrea De Nicola
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Nico Adorante
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Ramon Gimenez De Lorenzo
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Monica Di Tommaso
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Annamaria Vinciguerra
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Marianna Trignani
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Francesca Perrotti
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Albina Allajbej
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Andrea Fidanzio
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Francesca Greco
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Mattia Grusio
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Domenico Genovesi
- 1 Department of Radiation Oncology "G. D'Annunzio", University of Chieti, SS. Annunziata Hospital, Chieti, Italy
| | - Angelo Piermattei
- 2 Unità Operativa di Fisica Sanitaria; Fondazione Policlinico Universitario A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
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Wang X, Chen L, Xie C, Wang D, Chen G, Fu Z, Liu H. Experimental verification of a 3D in vivo dose monitoring system based on EPID. Oncotarget 2017; 8:109619-109631. [PMID: 29312634 PMCID: PMC5752547 DOI: 10.18632/oncotarget.22758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 10/28/2017] [Indexed: 11/25/2022] Open
Abstract
Purpose To evaluate the Edose system, a novel three-dimensional (3D) in vivo dose monitoring system based on electronic portal imaging device (EPID), prior to clinical application, we analyzed the preliminary clinical data using Edose system in patients receiving intensity-modulated radiation therapy (IMRT). Materials and methods After the physical modeling, the measured results from the Edose system were examined in homogeneous and inhomogeneous phantoms, respectively. To verify the accuracy of the Edose system, we compared its results with testing results from ionization chamber, measurement matrix (Delta4) and dosimetric films. The dosimetric performance of the Edose system was evaluated in 12 randomly selected patients with IMRT and VMAT, and the measured results were compared with the treatment plans. Results Compared with the measured results, the dose difference at the center of target volume was (0.12±0.91)% and (0.03±0.85)%, the γ pass rate was (94.18±1.69)% and (95.24±1.62)% (3mm/3%)for homogeneous and inhomogeneous phantoms, respectively. For IMRT patients, the dose difference at the center of target volume was (0.75±1.53)%, and the γ pass rates were (89.11±3.24)% (3mm/3%) and (96.40±1.47)% (3mm/5%), respectively. Compared with the results of DVH, the maximum differences of PTVs and mostly organs at risk were all within 3%. For VMAT patients, the γ pass rates were (93.04 ± 2.62)% (3mm/3%) and (97.92 ± 1.38)% (3mm/5%), respectively. Conclusions In vivo dose monitoring may further improve the safety and quality assurance for radiation therapy. But rigorous clinical testing is required before putting the existing commercial systems into clinical application. In addition, more clinical experiences and better workflows for using the Edose system are needed.
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Affiliation(s)
- Xiaoyong Wang
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, 430071 Wuhan, China
| | - Lixin Chen
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, 510060 Guangzhou, China
| | - Conghua Xie
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, 430071 Wuhan, China
| | - Dajiang Wang
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, 430071 Wuhan, China
| | - Gaili Chen
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, 430071 Wuhan, China
| | - Zhengming Fu
- Cancer Center, Renmin Hospital of Wuhan University, 430060 Wuhan, China
| | - Hui Liu
- Department of Radiation and Medical Oncology, Zhongnan Hospital of Wuhan University, 430071 Wuhan, China
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McCurdy BM, McCowan PM. In vivo dosimetry for lung radiotherapy including SBRT. Phys Med 2017; 44:123-130. [DOI: 10.1016/j.ejmp.2017.05.065] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 05/20/2017] [Accepted: 05/22/2017] [Indexed: 12/18/2022] Open
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Lim-Reinders S, Keller BM, Al-Ward S, Sahgal A, Kim A. Online Adaptive Radiation Therapy. Int J Radiat Oncol Biol Phys 2017; 99:994-1003. [DOI: 10.1016/j.ijrobp.2017.04.023] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 04/14/2017] [Indexed: 10/19/2022]
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Comparison of gamma- and DVH-based in vivo dosimetric plan evaluation for pelvic VMAT treatments. Radiother Oncol 2017; 125:405-410. [PMID: 29017719 DOI: 10.1016/j.radonc.2017.09.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/25/2017] [Accepted: 09/15/2017] [Indexed: 12/25/2022]
Abstract
BACKGROUND AND PURPOSE To compare DVH-based quality assurance to a multi-parametric γ-based methodology for in vivo EPID dosimetry for VMAT to the pelvis. MATERIALS AND METHODS For 47 rectum, 37 prostate, and 44 bladder VMAT treatments we reconstructed the 3D dose distributions of 387 fractions from in vivo EPID dosimetry. The difference between planned and measured dose was evaluated using γ analysis (3%/3mm) in the 50% isodose volume (IDV) and DVH differences (ΔD2, ΔD50 and ΔD98) of targets and organs at risk. The γ-indicators mean γ, γ pass rate and γ1% were compared to DVH-differences and their correlations were studied. DVH-based alerts on PTV and IDV were compared to γ-based alerts. RESULTS Average PTV D50 and D98 dose differences were 0.0±2.2% (1SD) and -1.4±2.9% (1SD). Alert criteria of |ΔD50|<3.5-4.5% corresponded to an alert rate of about 10%. Strong correlations between mean γ and γ pass rate and difference in PTV ΔD50 were observed for all sites. DVH- and γ-based alerts agreed on >80% of the fractions for the majority of compared alert thresholds and methods. This agreement is >90% for the larger deviations. CONCLUSIONS Strong correlations between some γ- and DVH indicators were found. Our comparison of multi-parametric alert strategies showed clinical equivalence for γ- and DVH-based methods.
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EPID-based in vivo dosimetry for stereotactic body radiotherapy of non-small cell lung tumors: Initial clinical experience. Phys Med 2017; 42:157-161. [PMID: 29173910 DOI: 10.1016/j.ejmp.2017.09.133] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 09/19/2017] [Accepted: 09/21/2017] [Indexed: 11/20/2022] Open
Abstract
PURPOSE EPID-based in vivo dosimetry (IVD) has been implemented for stereotactic body radiotherapy treatments of non-small cell lung cancer to check both isocenter dose and the treatment reproducibility comparing EPID portal images. METHODS 15 patients with lung tumors of small dimensions and treated with volumetric modulated arc therapy were enrolled for this initial experience. IVD tests supplied ratios R between in vivo reconstructed and planned isocenter doses. Moreover a γ-like analysis between daily EPID portal images and a reference one, in terms of percentage of points with γ-value smaller than 1, Pγ<1, and mean γ-values, γmean, using a local 3%-3mm criteria, was adopted to check the treatment reproducibility. Tolerance levels of 5% for R ratio, Pγ<1 higher than 90% and γmean lower than 0.67 were adopted. RESULTS A total of 160 EPID images, two images for each therapy session, were acquired during the treatment of the 15 patients. The overall mean of the R ratios was equal to 1.005±0.014 (1 SD), with 96.9% of tests within±5%. The 2D image γ-like analysis showed an overall γmean of 0.39±0.12 with 96.1% of tests within the tolerance level, and an average Pγ<1 value equal to 96.4±3.6% with 95.4% of tests with Pγ<1>90%. Paradigmatic discrepancies were observed in three patients: a set-up error and a patient morphological change were identified thanks to CBCT image analysis whereas the third discrepancy was not fully justified. CONCLUSIONS This procedure can provide improved patient safety as well as a first step to integrate IVD and CBCT dose recalculation.
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Wolfs CJA, Brás MG, Schyns LEJR, Nijsten SMJJG, van Elmpt W, Scheib SG, Baltes C, Podesta M, Verhaegen F. Detection of anatomical changes in lung cancer patients with 2D time-integrated, 2D time-resolved and 3D time-integrated portal dosimetry: a simulation study. Phys Med Biol 2017; 62:6044-6061. [PMID: 28582267 DOI: 10.1088/1361-6560/aa7730] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The aim of this work is to assess the performance of 2D time-integrated (2D-TI), 2D time-resolved (2D-TR) and 3D time-integrated (3D-TI) portal dosimetry in detecting dose discrepancies between the planned and (simulated) delivered dose caused by simulated changes in the anatomy of lung cancer patients. For six lung cancer patients, tumor shift, tumor regression and pleural effusion are simulated by modifying their CT images. Based on the modified CT images, time-integrated (TI) and time-resolved (TR) portal dose images (PDIs) are simulated and 3D-TI doses are calculated. The modified and original PDIs and 3D doses are compared by a gamma analysis with various gamma criteria. Furthermore, the difference in the D 95% (ΔD 95%) of the GTV is calculated and used as a gold standard. The correlation between the gamma fail rate and the ΔD 95% is investigated, as well the sensitivity and specificity of all combinations of portal dosimetry method, gamma criteria and gamma fail rate threshold. On the individual patient level, there is a correlation between the gamma fail rate and the ΔD 95%, which cannot be found at the group level. The sensitivity and specificity analysis showed that there is not one combination of portal dosimetry method, gamma criteria and gamma fail rate threshold that can detect all simulated anatomical changes. This work shows that it will be more beneficial to relate portal dosimetry and DVH analysis on the patient level, rather than trying to quantify a relationship for a group of patients. With regards to optimizing sensitivity and specificity, different combinations of portal dosimetry method, gamma criteria and gamma fail rate should be used to optimally detect certain types of anatomical changes.
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Affiliation(s)
- Cecile J A Wolfs
- Department of Radiation Oncology (MAASTRO), GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
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Abstract
PURPOSE To improve patient safety and treatment quality, verification of dose delivery in radiotherapy is desirable. We present a simple, easy-to-implement, open-source method for in vivo planar dosimetry of conformal radiotherapy by electronic portal imaging device (EPID). METHODS Correlation ratios, which relate dose in the mid-depth of slab phantoms to transit EPID signal, were determined for multiple phantom thicknesses and field sizes. Off-axis dose is corrected for by means of model-based convolution. We tested efficacy of dose reconstruction through measurements with off-reference values of attenuator thickness, field size, and monitor units. We quantified the dose calculation error in the presence of thickness changes to simulate anatomical or setup variations. An example of dose calculation on patient data is provided. RESULTS With varying phantom thickness, field size, and monitor units, dose reconstruction was almost always within 3% of planned dose. In the presence of thickness changes from planning CT, the dose discrepancy is exaggerated by up to approximately 1.5% for 1 cm changes upstream of the isocenter plane and 4% for 1 cm changes downstream. CONCLUSION Our novel electronic portal imaging device in vivo dosimetry allows clinically accurate 2-dimensional reconstruction of dose inside a phantom/patient at isocenter depth. Due to its simplicity, commissioning can be performed in a few hours per energy and may be modified to the user's needs. It may provide useful dose delivery information to detect harmful errors, guide adaptive radiotherapy, and assure quality of treatment.
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Affiliation(s)
- Stefano Peca
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada
| | - Derek Wilson Brown
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Radiation Medicine and Applied Sciences, Moores Cancer Center, UC San Diego, La Jolla, CA, USA
| | - Wendy Lani Smith
- Department of Physics and Astronomy, University of Calgary, Calgary, AB, Canada.,Department of Medical Physics, Tom Baker Cancer Centre, Calgary, AB, Canada.,Department of Radiation Oncology, University of Calgary, Calgary, AB, Canada
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Abstract
Although many error pathways are common to both stereotactic body radiation therapy (SBRT) and conventional radiation therapy, SBRT presents a special set of challenges including short treatment courses and high-doses, an enhanced reliance on imaging, technical challenges associated with commissioning, special resource requirements for staff and training, and workflow differences. Emerging data also suggest that errors occur at a higher rate in SBRT treatments. Furthermore, when errors do occur they often have a greater effect on SBRT treatments. Given these challenges, it is important to understand and employ systematic approaches to ensure the quality and safety of SBRT treatment. Here, we outline the pathways by which error can occur in SBRT, illustrated through a series of case studies, and highlight 9 specific well-established tools to either reduce error or minimize its effect to the patient or both.
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Affiliation(s)
- Eric Ford
- Department of Radiation Oncology, University of Washington, Seattle, WA.
| | - Sonja Dieterich
- Department of Radiation Oncology, University of California, Davis, CA
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Passarge M, Fix MK, Manser P, Stampanoni MFM, Siebers JV. A Swiss cheese error detection method for real-time EPID-based quality assurance and error prevention. Med Phys 2017; 44:1212-1223. [PMID: 28134989 DOI: 10.1002/mp.12142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 01/15/2017] [Accepted: 01/16/2017] [Indexed: 01/17/2023] Open
Abstract
PURPOSE To develop a robust and efficient process that detects relevant dose errors (dose errors of ≥5%) in external beam radiation therapy and directly indicates the origin of the error. The process is illustrated in the context of electronic portal imaging device (EPID)-based angle-resolved volumetric-modulated arc therapy (VMAT) quality assurance (QA), particularly as would be implemented in a real-time monitoring program. METHODS A Swiss cheese error detection (SCED) method was created as a paradigm for a cine EPID-based during-treatment QA. For VMAT, the method compares a treatment plan-based reference set of EPID images with images acquired over each 2° gantry angle interval. The process utilizes a sequence of independent consecutively executed error detection tests: an aperture check that verifies in-field radiation delivery and ensures no out-of-field radiation; output normalization checks at two different stages; global image alignment check to examine if rotation, scaling, and translation are within tolerances; pixel intensity check containing the standard gamma evaluation (3%, 3 mm) and pixel intensity deviation checks including and excluding high dose gradient regions. Tolerances for each check were determined. To test the SCED method, 12 different types of errors were selected to modify the original plan. A series of angle-resolved predicted EPID images were artificially generated for each test case, resulting in a sequence of precalculated frames for each modified treatment plan. The SCED method was applied multiple times for each test case to assess the ability to detect introduced plan variations. To compare the performance of the SCED process with that of a standard gamma analysis, both error detection methods were applied to the generated test cases with realistic noise variations. RESULTS Averaged over ten test runs, 95.1% of all plan variations that resulted in relevant patient dose errors were detected within 2° and 100% within 14° (<4% of patient dose delivery). Including cases that led to slightly modified but clinically equivalent plans, 89.1% were detected by the SCED method within 2°. Based on the type of check that detected the error, determination of error sources was achieved. With noise ranging from no random noise to four times the established noise value, the averaged relevant dose error detection rate of the SCED method was between 94.0% and 95.8% and that of gamma between 82.8% and 89.8%. CONCLUSIONS An EPID-frame-based error detection process for VMAT deliveries was successfully designed and tested via simulations. The SCED method was inspected for robustness with realistic noise variations, demonstrating that it has the potential to detect a large majority of relevant dose errors. Compared to a typical (3%, 3 mm) gamma analysis, the SCED method produced a higher detection rate for all introduced dose errors, identified errors in an earlier stage, displayed a higher robustness to noise variations, and indicated the error source.
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Affiliation(s)
- Michelle Passarge
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital Bern University Hospital and University of Bern, Berne, 3010, Switzerland.,Department of Radiation Oncology, University of Virginia Health System, Charlottesville, 22908, Virginia, USA
| | - Michael K Fix
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital Bern University Hospital and University of Bern, Berne, 3010, Switzerland
| | - Peter Manser
- Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital Bern University Hospital and University of Bern, Berne, 3010, Switzerland
| | - Marco F M Stampanoni
- Institute for Biomedical Engineering, Swiss Federal Institute of Technology (ETH), Zurich, 8092, Switzerland.,Paul Scherrer Institute (PSI), Villigen, 5232, Switzerland
| | - Jeffrey V Siebers
- Department of Radiation Oncology, University of Virginia Health System, Charlottesville, 22908, Virginia, USA
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Spreeuw H, Rozendaal R, Olaciregui-Ruiz I, González P, Mans A, Mijnheer B, van Herk M. Online 3D EPID-based dose verification: Proof of concept. Med Phys 2017; 43:3969. [PMID: 27370115 DOI: 10.1118/1.4952729] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
PURPOSE Delivery errors during radiotherapy may lead to medical harm and reduced life expectancy for patients. Such serious incidents can be avoided by performing dose verification online, i.e., while the patient is being irradiated, creating the possibility of halting the linac in case of a large overdosage or underdosage. The offline EPID-based 3D in vivo dosimetry system clinically employed at our institute is in principle suited for online treatment verification, provided the system is able to complete 3D dose reconstruction and verification within 420 ms, the present acquisition time of a single EPID frame. It is the aim of this study to show that our EPID-based dosimetry system can be made fast enough to achieve online 3D in vivo dose verification. METHODS The current dose verification system was sped up in two ways. First, a new software package was developed to perform all computations that are not dependent on portal image acquisition separately, thus removing the need for doing these calculations in real time. Second, the 3D dose reconstruction algorithm was sped up via a new, multithreaded implementation. Dose verification was implemented by comparing planned with reconstructed 3D dose distributions delivered to two regions in a patient: the target volume and the nontarget volume receiving at least 10 cGy. In both volumes, the mean dose is compared, while in the nontarget volume, the near-maximum dose (D2) is compared as well. The real-time dosimetry system was tested by irradiating an anthropomorphic phantom with three VMAT plans: a 6 MV head-and-neck treatment plan, a 10 MV rectum treatment plan, and a 10 MV prostate treatment plan. In all plans, two types of serious delivery errors were introduced. The functionality of automatically halting the linac was also implemented and tested. RESULTS The precomputation time per treatment was ∼180 s/treatment arc, depending on gantry angle resolution. The complete processing of a single portal frame, including dose verification, took 266 ± 11 ms on a dual octocore Intel Xeon E5-2630 CPU running at 2.40 GHz. The introduced delivery errors were detected after 5-10 s irradiation time. CONCLUSIONS A prototype online 3D dose verification tool using portal imaging has been developed and successfully tested for two different kinds of gross delivery errors. Thus, online 3D dose verification has been technologically achieved.
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Affiliation(s)
- Hanno Spreeuw
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Roel Rozendaal
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Igor Olaciregui-Ruiz
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Patrick González
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Anton Mans
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Ben Mijnheer
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam 1066 CX, The Netherlands
| | - Marcel van Herk
- The University of Manchester, Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester M20 4BX, United Kingdom
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McCowan PM, Asuni G, Van Uytven E, VanBeek T, McCurdy BMC, Loewen SK, Ahmed N, Bashir B, Butler JB, Chowdhury A, Dubey A, Leylek A, Nashed M. Clinical Implementation of a Model-Based In Vivo Dose Verification System for Stereotactic Body Radiation Therapy-Volumetric Modulated Arc Therapy Treatments Using the Electronic Portal Imaging Device. Int J Radiat Oncol Biol Phys 2017; 97:1077-1084. [PMID: 28332992 DOI: 10.1016/j.ijrobp.2017.01.227] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Revised: 12/27/2016] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To report findings from an in vivo dosimetry program implemented for all stereotactic body radiation therapy patients over a 31-month period and discuss the value and challenges of utilizing in vivo electronic portal imaging device (EPID) dosimetry clinically. METHODS AND MATERIALS From December 2013 to July 2016, 117 stereotactic body radiation therapy-volumetric modulated arc therapy patients (100 lung, 15 spine, and 2 liver) underwent 602 EPID-based in vivo dose verification events. A developed model-based dose reconstruction algorithm calculates the 3-dimensional dose distribution to the patient by back-projecting the primary fluence measured by the EPID during treatment. The EPID frame-averaging was optimized in June 2015. For each treatment, a 3%/3-mm γ comparison between our EPID-derived dose and the Eclipse AcurosXB-predicted dose to the planning target volume (PTV) and the ≥20% isodose volume were performed. Alert levels were defined as γ pass rates <85% (lung and liver) and <80% (spine). Investigations were carried out for all fractions exceeding the alert level and were classified as follows: EPID-related, algorithmic, patient setup, anatomic change, or unknown/unidentified errors. RESULTS The percentages of fractions exceeding the alert levels were 22.6% for lung before frame-average optimization and 8.0% for lung, 20.0% for spine, and 10.0% for liver after frame-average optimization. Overall, mean (± standard deviation) planning target volume γ pass rates were 90.7% ± 9.2%, 87.0% ± 9.3%, and 91.2% ± 3.4% for the lung, spine, and liver patients, respectively. CONCLUSIONS Results from the clinical implementation of our model-based in vivo dose verification method using on-treatment EPID images is reported. The method is demonstrated to be valuable for routine clinical use for verifying delivered dose as well as for detecting errors.
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Affiliation(s)
- Peter M McCowan
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada.
| | - Ganiyu Asuni
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Eric Van Uytven
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Timothy VanBeek
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Boyd M C McCurdy
- Medical Physics Department, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Radiology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Shaun K Loewen
- Department of Oncology, University of Calgary, Calgary, Alberta, Canada
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Hsieh ES, Hansen KS, Kent MS, Saini S, Dieterich S. Can a commercially available EPID dosimetry system detect small daily patient setup errors for cranial IMRT/SRS? Pract Radiat Oncol 2016; 7:e283-e290. [PMID: 28336480 DOI: 10.1016/j.prro.2016.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/26/2016] [Accepted: 12/20/2016] [Indexed: 11/26/2022]
Abstract
PURPOSE The purpose of this study was to determine if the Sun Nuclear PerFRACTION electronic portal imager device dosimetry software would be able to detect setup errors in a clinical setting and would be able to correctly identify the direction in which the setup error was introduced. METHODS AND MATERIALS A 7-field intensity modulated radiation therapy (IMRT) treatment plan for a centrally located tumor was developed for 1 phantom and 5 canine cadaver heads. Systematic setup errors were introduced by manually moving the treatment couch by 1, 3, and 5 mm in each translational direction to assess stereotactic radiation surgery (SRS), IMRT, and 3-dimensional (3D) treatment tolerances after the initial alignment was performed. An angular setup error of 5° yaw was also assessed. The delivered treatment fluence was automatically imported in the PerFRACTION software and compared with the baseline fluence. RESULTS In the canine phantom, a 5-mm shift was undetected by gamma analysis, and up to a 2-cm shift had to be introduced for the gamma pass rate of 3%/3 mm to fall below a 95% pass rate criterion. The same 5-mm shift using 3% difference caused the pass rates for 2 fields to drop below the 95% tolerance. For each respective translational shift, the affected beam angles were consistent across the cadaver heads and correlated with the direction of translational shift. The best field pass rate, worst field pass rate, and average pass rate across all 7 fields was analyzed to develop clinical guidance on parameter settings for SRS, IMRT, and 3D tolerances. CONCLUSIONS PerFRACTION 2-dimensional mode successfully detected setup errors outside the systematic error tolerance for SRS, IMRT, and 3D when an appropriate analysis metric and pass/fail criteria was implemented. Our data confirm that percent difference may be more sensitive in detecting plan failure than gamma analysis.
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Affiliation(s)
- Emmelyn S Hsieh
- School of Veterinary Medicine, University of California, Davis, Davis, California
| | - Katherine S Hansen
- Department of Surgical and Radiological Sciences, UC, Davis School of Veterinary Medicine, Davis, California
| | - Michael S Kent
- Department of Surgical and Radiological Sciences, UC, Davis School of Veterinary Medicine, Davis, California
| | | | - Sonja Dieterich
- Department of Radiation Oncology, University of California Davis School of Medicine, Sacramento, California.
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Han B, Ding A, Lu M, Xing L. Pixel response-based EPID dosimetry for patient specific QA. J Appl Clin Med Phys 2016; 18:9-17. [PMID: 28291939 PMCID: PMC5393354 DOI: 10.1002/acm2.12007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/26/2016] [Indexed: 11/25/2022] Open
Abstract
Increasing use of high dose rate, flattening filter free (FFF), and/or small‐sized field beams presents a significant challenge to the medical physics community. In this work, we develop a strategy of using a high spatial resolution and high frame rate amorphous silicon flat panel electronic portal imaging device (EPID) for dosimetric measurements of these challenging cases, as well as for conventional external beam therapy. To convert a series of raw EPID‐measured radiation field images into water‐based dose distribution, a pixel‐to‐pixel dose–response function of the EPID specific to the linac is essential. The response function was obtained by using a Monte Carlo simulation of the photon transport in the EPID with a comprehensive calibration. After the raw image was converted into the primary incident photon fluence, the fluence was further convolved into a water‐based dose distribution of the dynamic field by using a pregenerated pencil‐beam kernel. The EPID‐based dosimetric measurement technique was validated using beams with and without flattening filter of all energies available in Varian TrueBeam STx™. Both regularly and irregularly shaped fields measured using a PTW 729 ion chamber array in plastic water phantom. The technique was also applied to measure the distribution for a total of 23 treatment plans of different energies to evaluate the accuracy of the proposed approach. The EPID measurements of square fields of 4 × 4 cm2 to 20 × 20 cm2, circular fields of 2–15 cm diameters, rectangular fields of various sizes, and irregular MLC fields were in accordance with measurements using a Farmer chamber and/or ion chamber array. The 2D absolute dose maps generated from EPID raw images agreed with ion chamber measurements to within 1.5% for all fields. For the 23 patient cases examined in this work, the average γ‐index passing rate were found to be 99.2 ± 0.6%, 97.4 ± 2.4%, and 72.6 ± 8.4%, respectively, for criterions of 3 mm/3%, 2 mm/2%, and 1 mm/1%. The high spatial resolution and high frame rate EPID provides an accurate and efficient dosimetric tool for QA of modern radiation therapy. Accurate absolute 2D dose maps can be generated from the system for an independent dosimetric verification of treatment delivery.
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Affiliation(s)
- Bin Han
- Radiation Oncology Department, Stanford University, Stanford, CA, USA
| | - Aiping Ding
- Radiation Oncology Department, Stanford University, Stanford, CA, USA
| | - Minghui Lu
- Perkin Elmer Medical Imaging, Santa Clara, CA, USA
| | - Lei Xing
- Radiation Oncology Department, Stanford University, Stanford, CA, USA
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80
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In silico investigation of factors affecting the MV imaging performance of a novel water-equivalent EPID. Phys Med 2016; 32:1819-1826. [DOI: 10.1016/j.ejmp.2016.09.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 11/21/2022] Open
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81
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Jomehzadeh A, Shokrani P, Mohammadi M, Amouheidari A. Assessment of a 2D electronic portal imaging devices-based dosimetry algorithm for pretreatment and in-vivo midplane dose verification. Adv Biomed Res 2016; 5:171. [PMID: 28028511 PMCID: PMC5157032 DOI: 10.4103/2277-9175.194799] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 05/12/2014] [Indexed: 11/22/2022] Open
Abstract
Background: The use of electronic portal imaging devices (EPIDs) is a method for the dosimetric verification of radiotherapy plans, both pretreatment and in vivo. The aim of this study is to test a 2D EPID-based dosimetry algorithm for dose verification of some plans inside a homogenous and anthropomorphic phantom and in vivo as well. Materials and Methods: Dose distributions were reconstructed from EPID images using a 2D EPID dosimetry algorithm inside a homogenous slab phantom for a simple 10 × 10 cm2 box technique, 3D conformal (prostate, head-and-neck, and lung), and intensity-modulated radiation therapy (IMRT) prostate plans inside an anthropomorphic (Alderson) phantom and in the patients (one fraction in vivo) for 3D conformal plans (prostate, head-and-neck and lung). Results: The planned and EPID dose difference at the isocenter, on an average, was 1.7% for pretreatment verification and less than 3% for all in vivo plans, except for head-and-neck, which was 3.6%. The mean γ values for a seven-field prostate IMRT plan delivered to the Alderson phantom varied from 0.28 to 0.65. For 3D conformal plans applied for the Alderson phantom, all γ1% values were within the tolerance level for all plans and in both anteroposterior and posteroanterior (AP-PA) beams. Conclusion: The 2D EPID-based dosimetry algorithm provides an accurate method to verify the dose of a simple 10 × 10 cm2 field, in two dimensions, inside a homogenous slab phantom and an IMRT prostate plan, as well as in 3D conformal plans (prostate, head-and-neck, and lung plans) applied using an anthropomorphic phantom and in vivo. However, further investigation to improve the 2D EPID dosimetry algorithm for a head-and-neck case, is necessary.
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Affiliation(s)
- Ali Jomehzadeh
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran; Department of Medical Physics, School of Medicine, Rafsanjan University of Medical Sciences, Rafsanjan, Iran; Department of Medical Physics, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Parvaneh Shokrani
- Department of Medical Physics, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
| | | | - Alireza Amouheidari
- Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands
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Mans A, Schuring D, Arends MP, Vugts CAJM, Wolthaus JWH, Lotz HT, Admiraal M, Louwe RJW, Öllers MC, van de Kamer JB. The NCS code of practice for the quality assurance and control for volumetric modulated arc therapy. Phys Med Biol 2016; 61:7221-7235. [PMID: 27649474 DOI: 10.1088/0031-9155/61/19/7221] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In 2010, the NCS (Netherlands Commission on Radiation Dosimetry) installed a subcommittee to develop guidelines for quality assurance and control for volumetric modulated arc therapy (VMAT) treatments. The report (published in 2015) has been written by Dutch medical physicists and has therefore, inevitably, a Dutch focus. This paper is a condensed version of these guidelines, the full report in English is freely available from the NCS website www.radiationdosimetry.org. After describing the transition from IMRT to VMAT, the paper addresses machine quality assurance (QA) and treatment planning system (TPS) commissioning for VMAT. The final section discusses patient specific QA issues such as the use of class solutions, measurement devices and dose evaluation methods.
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Affiliation(s)
- Anton Mans
- Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands
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83
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Bojechko C, Ford EC. Quantifying the performance of in vivo portal dosimetry in detecting four types of treatment parameter variations. Med Phys 2016; 42:6912-8. [PMID: 26632047 DOI: 10.1118/1.4935093] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To quantify the ability of electronic portal imaging device (EPID) dosimetry used during treatment (in vivo) in detecting variations that can occur in the course of patient treatment. METHODS Images of transmitted radiation from in vivo EPID measurements were converted to a 2D planar dose at isocenter and compared to the treatment planning dose using a prototype software system. Using the treatment planning system (TPS), four different types of variability were modeled: overall dose scaling, shifting the positions of the multileaf collimator (MLC) leaves, shifting of the patient position, and changes in the patient body contour. The gamma pass rate was calculated for the modified and unmodified plans and used to construct a receiver operator characteristic (ROC) curve to assess the detectability of the different parameter variations. The detectability is given by the area under the ROC curve (AUC). The TPS was also used to calculate the impact of the variations on the target dose-volume histogram. RESULTS Nine intensity modulation radiation therapy plans were measured for four different anatomical sites consisting of 70 separate fields. Results show that in vivo EPID dosimetry was most sensitive to variations in the machine output, AUC = 0.70 - 0.94, changes in patient body habitus, AUC = 0.67 - 0.88, and systematic shifts in the MLC bank positions, AUC = 0.59 - 0.82. These deviations are expected to have a relatively small clinical impact [planning target volume (PTV) D99 change <7%]. Larger variations have even higher detectability. Displacements in the patient's position and random variations in MLC leaf positions were not readily detectable, AUC < 0.64. The D99 of the PTV changed by up to 57% for the patient position shifts considered here. CONCLUSIONS In vivo EPID dosimetry is able to detect relatively small variations in overall dose, systematic shifts of the MLC's, and changes in the patient habitus. Shifts in the patient's position which can introduce large changes in the target dose coverage were not readily detected.
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Affiliation(s)
- C Bojechko
- Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195
| | - E C Ford
- Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195
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84
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Ma T, Podgorsak MB, Kumaraswamy LK. Accuracy of one algorithm used to modify a planned DVH with data from actual dose delivery. J Appl Clin Med Phys 2016; 17:273-282. [PMID: 27685140 PMCID: PMC5874102 DOI: 10.1120/jacmp.v17i5.6344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/26/2016] [Accepted: 05/15/2016] [Indexed: 11/23/2022] Open
Abstract
Detection and accurate quantification of treatment delivery errors is important in radiation therapy. This study aims to evaluate the accuracy of DVH based QA in quantifying delivery errors. Eighteen previously treated VMAT plans (prostate, H&N, and brain) were randomly chosen for this study. Conventional IMRT delivery QA was done with the ArcCHECK diode detector for error-free plans and plans with the following modifications: 1) induced monitor unit differences up to ± 3.0%, 2) control point deletion (3, 5, and 8 control points were deleted for each arc), and 3) gantry angle shift (2° uniform shift clockwise and counterclockwise). 2D and 3D distance-to-agreement (DTA) analyses were performed for all plans with SNC Patient software and 3DVH software, respectively. Subsequently, accuracy of the reconstructed DVH curves and DVH parameters in 3DVH software were analyzed for all selected cases using the plans in the Eclipse treatment planning system as standard. 3D DTA analysis for error-induced plans generally gave high pass rates, whereas the 2D evaluation seemed to be more sensitive to detecting delivery errors. The average differences for DVH parameters between each pair of Eclipse recalculation and 3DVH prediction were within 2% for all three types of error-induced treatment plans. This illustrates that 3DVH accurately quantifies delivery errors in terms of actual dose delivered to the patients. 2D DTA analysis should be routinely used for clinical evaluation. Any concerns or dose discrepancies should be further analyzed through DVH-based QA for clinically relevant results and confirmation of a conventional passing-rate-based QA.
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Affiliation(s)
- Tianjun Ma
- Roswell Park Cancer Institute; State University of New York at Buffalo.
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85
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Investigation of a real-time EPID-based patient dose monitoring safety system using site-specific control limits. Radiat Oncol 2016; 11:106. [PMID: 27520279 PMCID: PMC4983007 DOI: 10.1186/s13014-016-0682-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 08/05/2016] [Indexed: 11/24/2022] Open
Abstract
Purpose The aim of this study is to investigate the performance and limitations of a real-time transit electronic portal imaging device (EPID) dosimetry system for error detection during dynamic intensity modulated radiation therapy (IMRT) treatment delivery. Sites studied are prostate, head and neck (HN), and rectal cancer treatments. Methods The system compares measured cumulative transit EPID image frames with predicted cumulative image frames in real-time during treatment using a χ comparison with 4 %, 4 mm criteria. The treatment site-specific thresholds (prostate, HN and rectum IMRT) were determined using initial data collected from 137 patients (274 measured treatment fractions) and a statistical process control methodology. These thresholds were then applied to data from 15 selected patients including 5 prostate, 5 HN, and 5 rectum IMRT treatments for system evaluation and classification of error sources. Results Clinical demonstration of real-time transit EPID dosimetry in IMRT was presented. For error simulation, the system could detect gross errors (i.e. wrong patient, wrong plan, wrong gantry angle) immediately after EPID stabilisation; 2 seconds after the start of treatment. The average rate of error detection was 7.0 % (prostate = 5.6 %, HN= 8.7 % and rectum = 6.7 %). The detected errors were classified as either clinical in origin (e.g. patient anatomical changes), or non-clinical in origin (e.g. detection system errors). Classified errors were 3.2 % clinical and 3.9 % non-clinical. Conclusion An EPID-based real-time error detection method for treatment verification during dynamic IMRT has been developed and tested for its performance and limitations. The system is able to detect gross errors in real-time, however improvement in system robustness is required to reduce the non-clinical sources of error detection.
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86
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Persoon L, Podesta M, Nijsten S, Troost E, Verhaegen F. Time-Resolved Versus Integrated Transit Planar Dosimetry for Volumetric Modulated Arc Therapy. Technol Cancer Res Treat 2016; 15:NP79-NP87. [PMID: 26655145 DOI: 10.1177/1533034615617668] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 09/16/2015] [Accepted: 10/23/2015] [Indexed: 11/16/2022] Open
Abstract
Purpose: It is desirable that dosimetric deviations during radiation treatments are detected. Integrated transit planar dosimetry is commonly used to evaluate external beam treatments such as volumetric-modulated arc therapy. This work focuses on patient geometry changes which result in differences between the planned and the delivered radiation dose. Integrated transit planar dosimetry will average out some deviations. Novel time-resolved transit planar dosimetry compares the delivered dose of volumetric-modulated arc therapy to the planned dose at various time points. Four patient cases are shown where time-resolved transit planar dosimetry detects patient geometry changes during treatment. Methods: A control point to control point comparison between the planned dose and the treatment dose of volumetric-modulated arc therapy beams is calculated using the planning computed tomography and the kV cone-beam computed tomography of the day and evaluated with a time-resolved γ function. Results were computed for 4 patients treated with volumetric-modulated arc therapy, each showing an anatomical change: pleural effusion, rectal gas pockets, and tumor regression. Results: In all cases, the geometrical change was detected by time-resolved transit planar dosimetry, whereas integrated transit planar dosimetry showed minor or no indication of the dose discrepancy. Both tumor regression cases were detected earlier in the treatment with time-resolved planar dosimetry in comparison to integrated transit planar dosimetry. The pleural effusion and the gas pocket were detected exclusively with time-resolved transit planar dosimetry. Conclusions: Clinical cases were presented in this proof-of-principle study in which integrated transit planar dosimetry did not detect dosimetrically relevant deviations to the same extent time-resolved transit planar dosimetry was able to. Time-resolved transit planar dosimetry also provides results that can be presented as a function of arc delivery angle allowing easier interpretation compared to integrated transit planar dosimetry.
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Affiliation(s)
- L.C.G.G. Persoon
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - M. Podesta
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - S.M.J.J.G. Nijsten
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - E.G.C. Troost
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - F. Verhaegen
- Department of Radiation Oncology (MAASTRO), GROW—School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, the Netherlands
- Medical Physics Unit, Department of Oncology, McGill University, Montréal, Québec, Canada
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87
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Huq MS, Fraass BA, Dunscombe PB, Gibbons JP, Ibbott GS, Mundt AJ, Mutic S, Palta JR, Rath F, Thomadsen BR, Williamson JF, Yorke ED. The report of Task Group 100 of the AAPM: Application of risk analysis methods to radiation therapy quality management. Med Phys 2016; 43:4209. [PMID: 27370140 PMCID: PMC4985013 DOI: 10.1118/1.4947547] [Citation(s) in RCA: 305] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 03/13/2016] [Accepted: 03/14/2016] [Indexed: 12/25/2022] Open
Abstract
The increasing complexity of modern radiation therapy planning and delivery challenges traditional prescriptive quality management (QM) methods, such as many of those included in guidelines published by organizations such as the AAPM, ASTRO, ACR, ESTRO, and IAEA. These prescriptive guidelines have traditionally focused on monitoring all aspects of the functional performance of radiotherapy (RT) equipment by comparing parameters against tolerances set at strict but achievable values. Many errors that occur in radiation oncology are not due to failures in devices and software; rather they are failures in workflow and process. A systematic understanding of the likelihood and clinical impact of possible failures throughout a course of radiotherapy is needed to direct limit QM resources efficiently to produce maximum safety and quality of patient care. Task Group 100 of the AAPM has taken a broad view of these issues and has developed a framework for designing QM activities, based on estimates of the probability of identified failures and their clinical outcome through the RT planning and delivery process. The Task Group has chosen a specific radiotherapy process required for "intensity modulated radiation therapy (IMRT)" as a case study. The goal of this work is to apply modern risk-based analysis techniques to this complex RT process in order to demonstrate to the RT community that such techniques may help identify more effective and efficient ways to enhance the safety and quality of our treatment processes. The task group generated by consensus an example quality management program strategy for the IMRT process performed at the institution of one of the authors. This report describes the methodology and nomenclature developed, presents the process maps, FMEAs, fault trees, and QM programs developed, and makes suggestions on how this information could be used in the clinic. The development and implementation of risk-assessment techniques will make radiation therapy safer and more efficient.
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Affiliation(s)
- M Saiful Huq
- Department of Radiation Oncology, University of Pittsburgh Cancer Institute and UPMC CancerCenter, Pittsburgh, Pennsylvania 15232
| | - Benedick A Fraass
- Department of Radiation Oncology, Cedars-Sinai Medical Center, Los Angeles, California 90048
| | - Peter B Dunscombe
- Department of Oncology, University of Calgary, Calgary T2N 1N4, Canada
| | | | - Geoffrey S Ibbott
- Department of Radiation Physics, UT MD Anderson Cancer Center, Houston, Texas 77030
| | - Arno J Mundt
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, San Diego, California 92093-0843
| | - Sasa Mutic
- Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Jatinder R Palta
- Department of Radiation Oncology, Virginia Commonwealth University, P.O. Box 980058, Richmond, Virginia 23298
| | - Frank Rath
- Department of Engineering Professional Development, University of Wisconsin, Madison, Wisconsin 53706
| | - Bruce R Thomadsen
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin 53705-2275
| | - Jeffrey F Williamson
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298-0058
| | - Ellen D Yorke
- Department of Medical Physics, Memorial Sloan-Kettering Center, New York, New York 10065
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88
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Kron T, Lehmann J, Greer PB. Dosimetry of ionising radiation in modern radiation oncology. Phys Med Biol 2016; 61:R167-205. [DOI: 10.1088/0031-9155/61/14/r167] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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89
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Yoon J, Jung JW, Kim JO, Yi BY, Yeo I. Four-dimensional dose reconstruction through in vivo
phase matching of cine images of electronic portal imaging device. Med Phys 2016; 43:4420. [DOI: 10.1118/1.4954317] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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90
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Schyns LEJR, Persoon LCGG, Podesta M, van Elmpt WJC, Verhaegen F. Time-resolved versus time-integrated portal dosimetry: the role of an object’s position with respect to the isocenter in volumetric modulated arc therapy. Phys Med Biol 2016; 61:3969-84. [PMID: 27156786 DOI: 10.1088/0031-9155/61/10/3969] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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91
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Ricketts K, Navarro C, Lane K, Moran M, Blowfield C, Kaur U, Cotten G, Tomala D, Lord C, Jones J, Adeyemi A. Implementation and evaluation of a transit dosimetry system for treatment verification. Phys Med 2016; 32:671-80. [PMID: 27134042 DOI: 10.1016/j.ejmp.2016.04.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 04/20/2016] [Accepted: 04/21/2016] [Indexed: 10/21/2022] Open
Abstract
PURPOSE To evaluate a formalism for transit dosimetry using a phantom study and prospectively evaluate the protocol on a patient population undergoing 3D conformal radiotherapy. METHODS Amorphous silicon EPIDs were calibrated for dose and used to acquire images of delivered fields. The measured EPID dose map was back-projected using the planning CT images to calculate dose at pre-specified points within the patient using commercially available software, EPIgray (DOSIsoft, France). This software compared computed back-projected dose with treatment planning system dose. A series of tests were performed on solid water phantoms (linearity, field size effects, off-axis effects). 37 patients were enrolled in the prospective study. RESULTS The EPID dose response was stable and linear with dose. For all tested field sizes the agreement was good between EPID-derived and treatment planning system dose in the central axis, with performance stability up to a measured depth of 18cm (agreement within -0.5% at 10cm depth on the central axis and within -1.4% at 2cm off-axis). 126 transit images were analysed of 37 3D-conformal patients. Patient results demonstrated the potential of EPIgray with 91% of all delivered fields achieved the initial set tolerance level of ΔD of 0±5-cGy or %ΔD of 0±5%. CONCLUSIONS The in vivo dose verification method was simple to implement, with very few commissioning measurements needed. The system required no extra dose to the patient, and importantly was able to detect patient position errors that impacted on dose delivery in two of cases.
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Affiliation(s)
- K Ricketts
- Division of Surgery and Interventional Sciences, University College London, London, UK; Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK.
| | - C Navarro
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - K Lane
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - M Moran
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - C Blowfield
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - U Kaur
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - G Cotten
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - D Tomala
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - C Lord
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - J Jones
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
| | - A Adeyemi
- Department of Radiotherapy Physics, Royal Berkshire NHS Foundation Trust, Reading, UK
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92
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Clinical Experience and Evaluation of Patient Treatment Verification With a Transit Dosimeter. Int J Radiat Oncol Biol Phys 2016; 95:1513-1519. [PMID: 27262359 DOI: 10.1016/j.ijrobp.2016.03.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 11/21/2022]
Abstract
PURPOSE To prospectively evaluate a protocol for transit dosimetry on a patient population undergoing intensity modulated radiation therapy (IMRT) and to assess the issues in clinical implementation of electronic portal imaging devices (EPIDs) for treatment verification. METHODS AND MATERIALS Fifty-eight patients were enrolled in the study. Amorphous silicon EPIDs were calibrated for dose and used to acquire images of delivered fields. Measured EPID dose maps were back-projected using the planning computed tomographic (CT) images to calculate dose at prespecified points within the patient and compared with treatment planning system dose offline using point dose difference and point γ analysis. The deviation of the results was used to inform future action levels. RESULTS Two hundred twenty-five transit images were analyzed, composed of breast, prostate, and head and neck IMRT fields. Patient measurements demonstrated the potential of the dose verification protocol to model dose well under complex conditions: 83.8% of all delivered beams achieved the initial set tolerance level of ΔD of 0 ± 5 cGy or %ΔD of 0% ± 5%. Importantly, the protocol was also sensitive to anatomic changes and spotted that 3 patients from 20 measured prostate patients had undergone anatomic change in comparison with the planning CT. Patient data suggested an EPID-reconstructed versus treatment planning system dose difference action level of 0% ± 7% for breast fields. Asymmetric action levels were more appropriate for inversed IMRT fields, using absolute dose difference (-2 ± 5 cGy) or summed field percentage dose difference (-6% ± 7%). CONCLUSIONS The in vivo dose verification method was easy to use and simple to implement, and it could detect patient anatomic changes that impacted dose delivery. The system required no extra dose to the patient or treatment time delay and so could be used throughout the course of treatment to identify and limit systematic and random errors in dose delivery for patient groups.
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93
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Gadhi MA, Fatmi S, Chughtai GM, Arshad M, Shakil M, Rahmani UM, Imran MY, Buzdar SA. Verification of absorbed dose using diodes in cobalt-60 radiation therapy. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2016; 39:211-9. [PMID: 26753835 DOI: 10.1007/s13246-016-0422-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 01/06/2016] [Indexed: 10/22/2022]
Abstract
The objective of this work was to enhance the quality and safety of dose delivery in the practice of radiation oncology. To achieve this goal, the absorbed dose verification program was initiated by using the diode in vivo dosimetry (IVD) system (for entrance and exit). This practice was implemented at BINO, Bahawalpur, Pakistan. Diodes were calibrated for making absorbed dose measurements. Various correction factors (SSD, dose non-linearity, field size, angle of incidence, and wedge) were determined for diode IVD system. The measurements were performed in phantom in order to validate the IVD procedure. One hundred and nineteen patients were monitored and 995 measurements were performed. For phantom, the percentage difference between measured and calculated dose for entrance setting remained within ±2% and for exit setting ±3%. For patient measurements, the percentage difference between measured and calculated dose remained within ±5% for entrance/open fields and ±7% for exit/wedge/oblique fields. One hundred and nineteen patients and 995 fields have been monitored during the period of 6 months. The analysis of all available measurements gave a mean percent deviation of ±1.19% and standard deviation of ±2.87%. Larger variations have been noticed in oblique, wedge and exit measurements. This investigation revealed that clinical dosimetry using diodes is simple, provides immediate results and is a useful quality assurance tool for dose delivery. It has enhanced the quality of radiation dose delivery and increased/improved the reliability of the radiation therapy practice in BINO.
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Affiliation(s)
- Muhammad Asghar Gadhi
- Medical Physics Department, Bahawalpur Institute of Nuclear Medicine and Oncology (BINO), Bahawalpur, Pakistan. .,Medical Physics Research Group, Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan.
| | - Shahab Fatmi
- Medical Physics Department, Bahawalpur Institute of Nuclear Medicine and Oncology (BINO), Bahawalpur, Pakistan
| | | | - Muhammad Arshad
- Medical Physics Department, Bahawalpur Institute of Nuclear Medicine and Oncology (BINO), Bahawalpur, Pakistan
| | - Muhammad Shakil
- Department of Physics, University of Gujrat, Gujrat, Pakistan
| | - Uzma Mahmood Rahmani
- Medical Physics Department, Bahawalpur Institute of Nuclear Medicine and Oncology (BINO), Bahawalpur, Pakistan
| | - Malik Younas Imran
- Medical Physics Department, Bahawalpur Institute of Nuclear Medicine and Oncology (BINO), Bahawalpur, Pakistan
| | - Saeed Ahmad Buzdar
- Medical Physics Research Group, Department of Physics, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
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94
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Chuter RW, Rixham PA, Weston SJ, Cosgrove VP. Feasibility of portal dosimetry for flattening filter-free radiotherapy. J Appl Clin Med Phys 2016; 17:112-120. [PMID: 26894337 PMCID: PMC5690198 DOI: 10.1120/jacmp.v17i1.5686] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 09/21/2015] [Accepted: 09/16/2015] [Indexed: 11/23/2022] Open
Abstract
The feasibility of using portal dosimetry (PD) to verify 6 MV flattening filter‐free (FFF) IMRT treatments was investigated. An Elekta Synergy linear accelerator with an Agility collimator capable of delivering FFF beams and a standard iViewGT amorphous silicon (aSi) EPID panel (RID 1640 AL5P) at a fixed SSD of 160 cm were used. Dose rates for FFF beams are up to four times higher than for conventional flattened beams, meaning images taken at maximum FFF dose rate can saturate the EPID. A dose rate of 800 MU/min was found not to saturate the EPID for open fields. This dose rate was subsequently used to characterize the EPID for FFF portal dosimetry. A range of open and phantom fields were measured with both an ion chamber and the EPID, to allow comparison between the two. The measured data were then used to create a model within The Nederlands Kanker Instituut's (NKI's) portal dosimetry software. The model was verified using simple square fields with a range of field sizes and phantom thicknesses. These were compared to calculations performed with the Monaco treatment planning system (TPS) and isocentric ion chamber measurements. It was found that the results for the FFF verification were similar to those for flattened beams with testing on square fields, indicating a difference in dose between the TPS and portal dosimetry of approximately 1%. Two FFF IMRT plans (prostate and lung SABR) were delivered to a homogeneous phantom and showed an overall dose difference at isocenter of ∼0.5% and good agreement between the TPS and PD dose distributions. The feasibility of using the NKI software without any modifications for high‐dose‐rate FFF beams and using a standard EPID detector has been investigated and some initial limitations highlighted. PACS number: 87.55.Qr
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95
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Imae T, Takenaka S, Watanabe Y, Okano Y, Nedu M, Saegusa S, Takeuchi Y, Yano K, Haga A, Shiraishi K, Yamashita H, Nakagawa K. [Evaluation of In Vivo Volumetric Dosimetry for Prostate Cancer Using Electronic Portal Imaging Device]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2016; 72:1128-1136. [PMID: 27867173 DOI: 10.6009/jjrt.2016_jsrt_72.11.1128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
PURPOSE Volumetric modulated arc therapy (VMAT) is capable of acquiring projection images using electronic portal imaging device (EPID). Commercial EPID-based dosimetry software, dosimetry check (DC), allows in vivo dosimetry using projection images. The purpose of this study was to evaluate in vivo dosimetry for prostate cancer using VMAT. METHOD VMAT plans were generated for eight patients with prostate cancer using treatment planning system (TPS), and patient quality assurances (QAs) were carried out with phantom. We analyzed five plans as phantom study and five plans as patient study. Projection images were acquired during VMAT delivery. DC converted acquired images into fluence images and used a pencil beam algorithm to calculate dose distributions delivered on the CT images of the phantom and the patients. We evaluated isocenter point doses and gamma analysis in both studies and dose indexes of planning target volume (PTV), bladder and rectum in patient study. RESULTS AND DISCUSSION Dose differences at the isocenter were less than a criterion in both studies. Pass rates of the gamma analysis were less than a criterion by two plans in the phantom study. Dose indexes of reconstructed distribution were lower than original plans and standard deviations of PTV in reconstructed distribution were larger than original plans. The errors were caused by some issues, such as the commissioning of DC, variations in patient anatomy, and patient positioning. CONCLUSION The method was feasible to non-invasively perform in vivo dose evaluation for prostate cancer using VMAT.
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Use of electronic portal imaging devices for electron treatment verification. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2015; 39:199-209. [PMID: 26581763 DOI: 10.1007/s13246-015-0401-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 11/04/2015] [Indexed: 11/27/2022]
Abstract
This study aims to help broaden the use of electronic portal imaging devices (EPIDs) for pre-treatment patient positioning verification, from photon-beam radiotherapy to photon- and electron-beam radiotherapy, by proposing and testing a method for acquiring clinically-useful EPID images of patient anatomy using electron beams, with a view to enabling and encouraging further research in this area. EPID images used in this study were acquired using all available beams from a linac configured to deliver electron beams with nominal energies of 6, 9, 12, 16 and 20 MeV, as well as photon beams with nominal energies of 6 and 10 MV. A widely-available heterogeneous, approximately-humanoid, thorax phantom was used, to provide an indication of the contrast and noise produced when imaging different types of tissue with comparatively realistic thicknesses. The acquired images were automatically calibrated, corrected for the effects of variations in the sensitivity of individual photodiodes, using a flood field image. For electron beam imaging, flood field EPID calibration images were acquired with and without the placement of blocks of water-equivalent plastic (with thicknesses approximately equal to the practical range of electrons in the plastic) placed upstream of the EPID, to filter out the primary electron beam, leaving only the bremsstrahlung photon signal. While the electron beam images acquired using a standard (unfiltered) flood field calibration were observed to be noisy and difficult to interpret, the electron beam images acquired using the filtered flood field calibration showed tissues and bony anatomy with levels of contrast and noise that were similar to the contrast and noise levels seen in the clinically acceptable photon beam EPID images. The best electron beam imaging results (highest contrast, signal-to-noise and contrast-to-noise ratios) were achieved when the images were acquired using the higher energy electron beams (16 and 20 MeV) when the EPID was calibrated using an intermediate (12 MeV) electron beam energy. These results demonstrate the feasibility of acquiring clinically-useful EPID images of patient anatomy using electron beams and suggest important avenues for future investigation, thus enabling and encouraging further research in this area. There is manifest potential for the EPID imaging method proposed in this work to lead to the clinical use of electron beam imaging for geometric verification of electron treatments in the future.
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97
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Van Uytven E, Van Beek T, McCowan PM, Chytyk-Praznik K, Greer PB, McCurdy BMC. Validation of a method for in vivo
3D dose reconstruction for IMRT and VMAT treatments using on-treatment EPID images and a model-based forward-calculation algorithm. Med Phys 2015; 42:6945-54. [DOI: 10.1118/1.4935199] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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98
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Woodruff HC, Fuangrod T, Van Uytven E, McCurdy BM, van Beek T, Bhatia S, Greer PB. First Experience With Real-Time EPID-Based Delivery Verification During IMRT and VMAT Sessions. Int J Radiat Oncol Biol Phys 2015; 93:516-22. [DOI: 10.1016/j.ijrobp.2015.07.2271] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 06/25/2015] [Accepted: 07/13/2015] [Indexed: 10/23/2022]
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Cilla S, Meluccio D, Fidanzio A, Azario L, Ianiro A, Macchia G, Digesù C, Deodato F, Valentini V, Morganti AG, Piermattei A. Initial clinical experience with Epid-based in-vivo dosimetry for VMAT treatments of head-and-neck tumors. Phys Med 2015; 32:52-8. [PMID: 26511150 DOI: 10.1016/j.ejmp.2015.09.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 07/29/2015] [Accepted: 09/28/2015] [Indexed: 11/17/2022] Open
Abstract
We evaluated an EPID-based in-vivo dosimetry algorithm (IVD) for complex VMAT treatments in clinical routine. 19 consecutive patients with head-and-neck tumors and treated with Elekta VMAT technique using Simultaneous Integrated Boost strategy were enrolled. In-vivo tests were evaluated by means of (i) ratio R between daily in-vivo isocenter dose and planned dose and (ii) γ-analysis between EPID integral portal images in terms of percentage of points with γ-value smaller than one (γ%) and mean γ-values (γmean), using a global 3%-3 mm criteria. Alert criteria of ±5% for R ratio, γ% < 90% and γmean > 0.67 were chosen. A total of 350 transit EPID images were acquired during the treatment fractions. The overall mean R ratio was equal to 1.002 ± 0.019 (1 SD), with 95.9% of tests within ±5%. The 2D portal images of γ-analysis showed an overall γmean of 0.42 ± 0.16 with 93.3% of tests within alert criteria, and a mean γ% equal to 92.9 ± 5.1% with 85.9% of tests within alert criteria. Relevant discrepancies were observed in three patients: a set-up error was detected for one patient and two patients showed major anatomical variations (weight loss/tumor shrinkage) in the second half of treatment. The results are supplied in quasi real-time, with IVD tests displayed after only 1 minute from the end of arc delivery. This procedure was able to detect when delivery was inconsistent with the original plans, allowing physics and medical staff to promptly act in case of major deviations between measured and planned dose.
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Affiliation(s)
- Savino Cilla
- Medical Physics Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy; Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, Roma, Italy.
| | - Daniela Meluccio
- Medical Physics Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy
| | - Andrea Fidanzio
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, Roma, Italy; Medical Physics Unit, Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Luigi Azario
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, Roma, Italy; Medical Physics Unit, Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Anna Ianiro
- Medical Physics Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy
| | - Gabriella Macchia
- Radiotherapy Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy
| | - Cinzia Digesù
- Radiotherapy Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy
| | - Francesco Deodato
- Radiotherapy Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy
| | - Vincenzo Valentini
- Radiotherapy Unit, Fondazione di Ricerca e Cura "Giovanni Paolo II", Campobasso, Italy; Radiotherapy Department, Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Alessio G Morganti
- Radiation Oncology Center, Department of Experimental, Diagnostic and Specialty Medicine - DIMES University of Bologna, S. Orsola-Malpighi Hospital, Bologna, Italy
| | - Angelo Piermattei
- Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Roma Tre, Roma, Italy; Medical Physics Unit, Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Roma, Italy
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do Amaral LL, de Oliveira HF, Pavoni JF, Sampaio F, Ghillardi Netto T. A new transmission methodology for quality assurance in radiotherapy based on radiochromic film measurements. J Appl Clin Med Phys 2015; 16:1-12. [PMID: 26699306 PMCID: PMC5690170 DOI: 10.1120/jacmp.v16i5.5497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 05/06/2015] [Accepted: 04/29/2015] [Indexed: 11/23/2022] Open
Abstract
Despite individual quality assurance (QA) being recommended for complex techniques in radiotherapy (RT) treatment, the possibility of errors in dose delivery during therapeutic application has been verified. Therefore, it is fundamentally important to conduct in vivo QA during treatment. This work presents an in vivo transmission quality control methodology, using radiochromic film (RCF) coupled to the linear accelerator (linac) accessory holder. This QA methodology compares the dose distribution measured by the film in the linac accessory holder with the dose distribution expected by the treatment planning software. The calculated dose distribution is obtained in the coronal and central plane of a phantom with the same dimensions of the acrylic support used for positioning the film but in a source-to-detector distance (SDD) of 100 cm, as a result of transferring the IMRT plan in question with all the fields positioned with the gantry vertically, that is, perpendicular to the phantom. To validate this procedure, first of all a Monte Carlo simulation using PENELOPE code was done to evaluate the differences between the dose distributions measured by the film in a SDD of 56.8 cm and 100 cm. After that, several simple dose distribution tests were evaluated using the proposed methodology, and finally a study using IMRT treatments was done. In the Monte Carlo simulation, the mean percentage of points approved in the gamma function comparing the dose distribution acquired in the two SDDs were 99.92% ± 0.14%. In the simple dose distribution tests, the mean percentage of points approved in the gamma function were 99.85% ± 0.26% and the mean percentage differences in the normalization point doses were -1.41%. The transmission methodology was approved in 24 of 25 IMRT test irradiations. Based on these results, it can be concluded that the proposed methodology using RCFs can be applied for in vivo QA in RT treatments.
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