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Kowatsch M, Szeverinski P, Clemens P, Künzler T, Söhn M, Alber M. Sensitivity and specificity of Monte Carlo based independent secondary dose computation for detecting modulation-related dose errors in intensity modulated radiotherapy. Z Med Phys 2023:S0939-3889(23)00117-4. [PMID: 37891103 DOI: 10.1016/j.zemedi.2023.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 08/09/2023] [Accepted: 10/06/2023] [Indexed: 10/29/2023]
Abstract
BACKGROUND The recent availability of Monte Carlo based independent secondary dose calculation (ISDC) for patient-specific quality assurance (QA) of modulated radiotherapy requires the definition of appropriate, more sensitive action levels, since contemporary recommendations were defined for less accurate ISDC dose algorithms. PURPOSE The objective is to establish an optimum action level and measure the efficacy of a Monte Carlo ISDC software for pre-treatment QA of intensity modulated radiotherapy treatments. METHODS The treatment planning system and the ISDC were commissioned by their vendors from independent base data sets, replicating a typical real-world scenario. In order to apply Receiver-Operator-Characteristics (ROC), a set of treatment plans for various case classes was created that consisted of 190 clinical treatment plans and 190 manipulated treatment plans with dose errors in the range of 1.5-2.5%. All 380 treatment plans were evaluated with ISDC in the patient geometry. ROC analysis was performed for a number of Gamma (dose-difference/distance-to-agreement) criteria. QA methods were ranked according to Area under the ROC curve (AUC) and optimum action levels were derived via Youden's J statistics. RESULTS Overall, for original treatment plans, the mean Gamma pass rate (GPR) for Gamma(1%, 1 mm) was close to 90%, although with some variation across case classes. The best QA criterion was Gamma(2%, 1 mm) with GPR > 90% and an AUC of 0.928. Gamma criteria with small distance-to-agreement had consistently higher AUC. GPR of original treatment plans depended on their modulation degree. An action level in terms of Gamma(1%, 1 mm) GPR that decreases with modulation degree was the most efficient criterion with sensitivity = 0.91 and specificity = 0.95, compared with Gamma(3%, 3 mm) GPR > 99%, sensitivity = 0.73 and specificity = 0.91 as a commonly used action level. CONCLUSIONS ISDC with Monte Carlo proves highly efficient to catch errors in the treatment planning process. For a Monte Carlo based TPS, dose-difference criteria of 2% or less, and distance-to-agreement criteria of 1 mm, achieve the largest AUC in ROC analysis.
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Affiliation(s)
- Matthias Kowatsch
- Institute of Medical Physics, Academic Teaching Hospital Feldkirch, Carinagasse 47, 6800 Feldkirch, Austria.
| | - Philipp Szeverinski
- Institute of Medical Physics, Academic Teaching Hospital Feldkirch, Carinagasse 47, 6800 Feldkirch, Austria
| | - Patrick Clemens
- Department of Radio-Oncology, Academic Teaching Hospital Feldkirch, Carinagasse 47, 6800 Feldkirch, Austria
| | - Thomas Künzler
- Institute of Medical Physics, Academic Teaching Hospital Feldkirch, Carinagasse 47, 6800 Feldkirch, Austria
| | - Matthias Söhn
- Scientific-RT GmbH, Welserstr. 7, 81373 München, Germany
| | - Markus Alber
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Scientific-RT GmbH, Welserstr. 7, 81373 München, Germany
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Electronic Portal Imaging Device in Pre-Treatment Patient-Specific Quality Assurance of volumetric-modulated arc therapy delivery. JOURNAL OF RADIOTHERAPY IN PRACTICE 2023. [DOI: 10.1017/s1460396922000334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Abstract
Background:
Radiotherapy treatment delivery is evaluated by a pre-treatment patient-specific quality assurance (PSQA) procedure to ensure the patient receives an accurate radiation dose. The current PSQA practice by using conventional phantoms requires more set-up time and cost of purchasing the tools. Therefore, this study aimed to investigate the efficiency of an electronic portal imaging device (EPID) of linear accelerator (LINAC) as a PSQA tool for volumetric-modulated arc therapy (VMAT) planning technique for nasopharyngeal carcinoma (NPC) treatment delivery.
Methods:
A NPC VMAT plan on a Rando phantom was performed by following the Radiation Therapy Oncology Group (RTOG) 0615 protocol. The gamma passing rate of the EPID and PSQA phantom (ArcCHECK) were compared among the gamma criteria of 3%/3 mm, 2%/2 mm and 1%/1 mm, respectively.
Results:
Both EPID and ArcCHECK phantom had distinguishable gamma passing rates in 3%/3 mm and 2%/2 mm with a difference of 0·87% and 0·30%, respectively. Meanwhile, the EPID system had a lower gamma passing rate than the ArcCHECK phantom in 1%/1 mm (21·23% difference). Furthermore, the sensitivity of the EPID system was evaluated and had the largest deviation in gamma passing rate from the reference position in gamma criteria of 2%/2 mm (41·14%) compared to the 3%/3 mm (25·45%) and 1%/1 mm (31·78%), discretely. The best fit line of the linear regression model for EPID was steeper than the ArcCHECK phantom in 3%/3 mm and 2%/2 mm, and vice versa in gamma criteria of 1%/1 mm. This indicates that the EPID had a higher sensitivity than the ArcCHECK phantom in 3%/3 mm and 2%/2 mm but less sensitivity in 1%/1 mm.
Conclusions:
The EPID system was efficient in performing the PSQA test of VMAT treatment in HUSM with the gamma criteria of 3%/3 mm and 2%/2 mm.
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Gong C, Zhu K, Lin C, Han C, Lu Z, Chen Y, Yu C, Hou L, Zhou Y, Yi J, Ai Y, Xiang X, Xie C, Jin X. Efficient dose-volume histogram-based pretreatment patient-specific quality assurance methodology with combined deep learning and machine learning models for volumetric modulated arc radiotherapy. Med Phys 2022; 49:7779-7790. [PMID: 36190117 DOI: 10.1002/mp.16010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 08/26/2022] [Accepted: 09/17/2022] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Weak correlation between gamma passing rates and dose differences in target volumes and organs at risk (OARs) has been reported in several studies. Evaluation on the differences between planned dose-volume histogram (DVH) and reconstructed DVH from measurement was adopted and incorporated into patient-specific quality assurance (PSQA). However, it is difficult to develop a methodology allowing the evaluation of errors on DVHs accurately and quickly. PURPOSE To develop a DVH-based pretreatment PSQA for volumetric modulated arc therapy (VMAT) with combined deep learning (DL) and machine learning models to overcome the limitation of conventional gamma index (GI) and improve the efficiency of DVH-based PSQA. METHODS A DL model with a three-dimensional squeeze-and-excitation residual blocks incorporated into a modified U-net was developed to predict the measured PSQA DVHs of 208 head-and-neck (H&N) cancer patients underwent VMAT between 2018 and 2021 from two hospitals, in which 162 cases was randomly selected for training, 18 for validation, and 28 for testing. After evaluating the differences between treatment planning system (TPS) and PSQA DVHs predicted by DL model with multiple metrics, a pass or fail (PoF) classification model was developed using XGBoost algorithm. Evaluation of domain experts on dose errors between TPS and reconstructed PSQA DVHs was taken as ground truth for PoF classification model training. RESULTS The prediction model was able to achieve a good agreement between predicted, measured, and TPS doses. Quantitative evaluation demonstrated no significant difference between predicted PSQA dose and measured dose for target and OARs, except for Dmean of PTV6900 (p = 0.001), D50 of PTV6000 (p = 0.014), D2 of PTV5400 (p = 0.009), D50 of left parotid (p = 0.015), and Dmax of left inner ear (p = 0.007). The XGBoost model achieved an area under curves, accuracy, sensitivity, and specificity of 0.89 versus 0.88, 0.89 versus 0.86, 0. 71 versus 0.71, and 0.95 versus 0.91 with measured and predicted PSQA doses, respectively. The agreement between domain experts and the classification model was 86% for 28 test cases. CONCLUSIONS The successful prediction of PSQA doses and classification of PoF for H&N VMAT PSQA indicating that this DVH-based PSQA method is promising to overcome the limitations of GI and to improve the efficiency and accuracy of VMAT delivery.
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Affiliation(s)
- Changfei Gong
- Radiation Oncology Department, 1st Affiliated Hospital of Nanchang Medical University, Nanchang, China.,Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Kecheng Zhu
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Chengyin Lin
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Ce Han
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhongjie Lu
- Radiation Oncology Department, 1st Affiliated Hospital of Medical School of Zhejiang University, Zhejiang, China
| | - Yuanhua Chen
- Radiation Oncology Department, 1st Affiliated Hospital of Medical School of Zhejiang University, Zhejiang, China
| | - Changhui Yu
- Radiation Oncology Department, Taizhou Hospital of Zhejiang Province, Taizhou, China
| | - Liqiao Hou
- Radiation Oncology Department, Taizhou Hospital of Zhejiang Province, Taizhou, China
| | - Yongqiang Zhou
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jinling Yi
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yao Ai
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiaojun Xiang
- Radiation Oncology Department, 1st Affiliated Hospital of Nanchang Medical University, Nanchang, China
| | - Congying Xie
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.,Radiation Oncology Department, 2nd Affiliated Hospital of Wenzhou Medical University, Wenzhou, China
| | - Xiance Jin
- Radiotherapy Center, 1st Affiliated Hospital of Wenzhou Medical University, Wenzhou, China.,School of Basic Medical Science, Wenzhou Medical University, Wenzhou, China
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Price RA, Veltchev I, Lin T, Eldib A, Chen L, Jin L, Chen X, Liu J, Wang L, Ma CMC. Evaluating suggested stricter gamma criteria for linac-based patient-specific delivery QA in the conventional and SBRT environments. Phys Med 2022; 100:72-80. [PMID: 35759942 DOI: 10.1016/j.ejmp.2022.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/01/2022] [Accepted: 06/11/2022] [Indexed: 10/17/2022] Open
Abstract
PURPOSE To evaluate AAPM TG-218 recommended tolerances for IMRT QA for conventional and SBRT delivery. METHODS QA analysis was repeated for 150 IMRT/VMAT patients with varying gamma criteria. True composite delivery was utilized, corrected for detector and output variation. Universal tolerance (TLuniv) and action limits (ALuniv) were compared with statistical process control (SPC) TLSPC and ALSPC values. Analysis was repeated as a function of plan complexity for 250 non-stereotactic body radiotherapy (SBRT) VMAT patients at 3%/2mm and a threshold of 10% and for 75 SBRT VMAT patients at 2%/2 mm and a threshold of 50% with results plotted as a function of PTV volume. Regions of failure were dose-scaled on the planning CT data sets based on delivery results. RESULTS The IMRT/VMAT TLSPC and ALSPC for gamma criteria of 3%/3 mm were 96.5% and 95.6% and for 3%/2 mm were 91.2% and 89.2%, respectively. Correlation with plan complexity for conventional fractionation VMAT was "low" for all sites with pelvis having the highest r value at -0.35. The equivalent SBRT PTV diameter ranged from 2.0 cm to 5.6 cm. Negative low correlation was found for 38 of 75 VMAT cases below ALuniv. CONCLUSIONS The ALuniv and ALSPC are similar for 3%/2 mm. However, our 5% failure rate for ALuniv, may result in treatment start delays approximately 2 times/month, given 40 new cases/month. VMAT QA failure at stricter criteria did not correlate strongly with plan complexity. Site-specific action limits vary less than 3% from the average. SBRT QA results do not strongly correlate with target size over the range studied.
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Affiliation(s)
- Robert A Price
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States.
| | - Iavor Veltchev
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Teh Lin
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Ahmed Eldib
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Lili Chen
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Lihui Jin
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Xiaoming Chen
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Jie Liu
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - Lu Wang
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
| | - C-M Charlie Ma
- Fox Chase Cancer Center, Department of Radiation Oncology, 333 Cottman Avenue, Philadelphia, PA 19111, United States
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Zhang H, Lu W, Cui H, Li Y, Yi X. Assessment of Statistical Process Control Based DVH Action Levels for Systematic Multi-Leaf Collimator Errors in Cervical Cancer RapidArc Plans. Front Oncol 2022; 12:862635. [PMID: 35664736 PMCID: PMC9157499 DOI: 10.3389/fonc.2022.862635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 04/19/2022] [Indexed: 11/18/2022] Open
Abstract
Background In the patient-specific quality assurance (QA), DVH is a critical clinically relevant parameter that is finally used to determine the safety and effectiveness of radiotherapy. However, a consensus on DVH-based action levels has not been reached yet. The aim of this study is to explore reasonable DVH-based action levels and optimal DVH metrics in detecting systematic MLC errors for cervical cancer RapidArc plans. Methods In this study, a total of 148 cervical cancer RapidArc plans were selected and measured with COMPASS 3D dosimetry system. Firstly, the patient-specific QA results of 110 RapidArc plans were retrospectively reviewed. Then, DVH-based action limits (AL) and tolerance limits (TL) were obtained by statistical process control. Secondly, systematic MLC errors were introduced in 20 RapidArc plans, generating 380 modified plans. Then, the dose difference (%DE) in DVH metrics between modified plans and original plans was extracted from measurement results. After that, the linear regression model was used to investigate the detection limits of DVH-based action levels between %DE and systematic MLC errors. Finally, a total of 180 test plans (including 162 error-introduced plans and 18 original plans) were prepared for validation. The error detection rate of DVH-based action levels was compared in different DVH metrics of 180 test plans. Results A linear correlation was found between systematic MLC errors and %DE in all DVH metrics. Based on linear regression model, the systematic MLC errors between -0.94 mm and 0.88 mm could be caught by the TL of PTV95 ([-1.54%, 1.51%]), and the systematic MLC errors between -1.00 mm and 0.80 mm could also be caught by the TL of PTVmean ([-2.06%, 0.38%]). In the validation, for original plans, PTV95 showed the minimum error detection rate of 5.56%. For error-introduced plans with systematic MLC errors more than 1mm, PTVmean showed the maximum error detection rate of 88.89%, and then was followed by PTV95 (86.67%). All the TL of DVH metrics showed a poor error detection rate in identifying error-induced plans with systematic MLC errors less than 1mm. Conclusion In 3D quality assurance of cervical cancer RapidArc plans, process-based tolerance limits showed greater advantages in distinguishing plans introduced with systematic MLC errors more than 1mm, and reasonable DVH-based action levels can be acquired through statistical process control. During DVH-based verification, main focus should be on the DVH metrics of target volume. OARs in low-dose regions were found to have a relatively higher dose sensitivity to smaller systematic MLC errors, but may be accompanied with higher false error detection rate.
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Affiliation(s)
- Hanyin Zhang
- Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Wenli Lu
- Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Haixia Cui
- Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Ying Li
- Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xin Yi
- Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China
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Gray A, Bawazeer O, Arumugam S, Vial P, Descallar J, Thwaites D, Holloway L. Evaluation of the ability of three commercially available dosimeters to detect systematic delivery errors in step-and-shoot IMRT plans. Rep Pract Oncol Radiother 2021; 26:793-803. [PMID: 34760314 DOI: 10.5603/rpor.a2021.0093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 07/03/2021] [Indexed: 11/25/2022] Open
Abstract
Background There is limited data on error detectability for step-and-shoot intensity modulated radiotherapy (sIMRT) plans, despite significant work on dynamic methods. However, sIMRT treatments have an ongoing role in clinical practice. This study aimed to evaluate variations in the sensitivity of three patient-specific quality assurance (QA) devices to systematic delivery errors in sIMRT plans. Materials and methods Four clinical sIMRT plans (prostate and head and neck) were edited to introduce errors in: Multi-Leaf Collimator (MLC) position (increasing field size, leaf pairs offset (1-3 mm) in opposite directions; and field shift, all leaves offset (1-3 mm) in one direction); collimator rotation (1-3 degrees) and gantry rotation (0.5-2 degrees). The total dose for each plan was measured using an ArcCHECK diode array. Each field, excluding those with gantry offsets, was also measured using an Electronic Portal Imager and a MatriXX Evolution 2D ionisation chamber array. 132 plans (858 fields) were delivered, producing 572 measured dose distributions. Measured doses were compared to calculated doses for the no-error plan using Gamma analysis with 3%/3 mm, 3%/2 mm, and 2%/2 mm criteria (1716 analyses). Results Generally, pass rates decreased with increasing errors and/or stricter gamma criteria. Pass rate variations with detector and plan type were also observed. For a 3%/3 mm gamma criteria, none of the devices could reliably detect 1 mm MLC position errors or 1 degree collimator rotation errors. Conclusions This work has highlighted the need to adapt QA based on treatment plan type and the need for detector specific assessment criteria to detect clinically significant errors.
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Affiliation(s)
- Alison Gray
- Liverpool and Macarthur Cancer Therapy Centres, South Western Sydney Local Health District, Sydney, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Omemh Bawazeer
- Physics Department, Umm Al-Qura University, Mecca, Saudi Arabia
| | - Sankar Arumugam
- Liverpool and Macarthur Cancer Therapy Centres, South Western Sydney Local Health District, Sydney, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Philip Vial
- Liverpool and Macarthur Cancer Therapy Centres, South Western Sydney Local Health District, Sydney, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia
| | - Joseph Descallar
- Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - David Thwaites
- Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia
| | - Lois Holloway
- Liverpool and Macarthur Cancer Therapy Centres, South Western Sydney Local Health District, Sydney, NSW, Australia.,Ingham Institute for Applied Medical Research, Sydney, NSW, Australia.,South Western Sydney Clinical School, School of Medicine, University of New South Wales, Sydney, NSW, Australia.,Institute of Medical Physics, School of Physics, University of Sydney, Sydney, NSW, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW, Australia
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Baran M, Tabor Z, Tulik M, Kabat D, Rzecki K, Sośnicki T, Waligórski M. Are gamma passing rate and dose-volume histogram QA metrics correlated? Med Phys 2021; 48:4743-4753. [PMID: 34342005 DOI: 10.1002/mp.15142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 05/19/2021] [Accepted: 07/26/2021] [Indexed: 11/11/2022] Open
Abstract
PURPOSE The quality of a measured distribution of dose delivered against its corresponding radiotherapy plan is routinely assessed by gamma index (GI) and dose-volume histogram (DVH) metrics. Any correlation between error detection rates, as based on either of these approaches, while argued, has never been convincingly demonstrated. The dependence of the strength of correlation between the GI passing rate ( γ P ) and DVH quality assurance (QA) metrics on various elements of the therapy plan has not been systematically investigated. METHODS A formal analysis of the relation between γ P and DVH metrics has been undertaken, leading to a relationship which may partly approximate γ P with respect to the DVH. This relationship was further validated by studying examples of simulated clinical radiotherapy plans and by studying the correlation between γ P and the derived relationship using a simple two-dimensional representations of the planning target volume (PTV) and organs at risk (OAR), where penumbra regions, distance-to-agreement tolerances and dose delivery errors were systematically varied. RESULTS It is shown formally that there cannot be any correlation between γ P and other commonly applied DVH-derived QA measures. However, γ P may be partly approximated given the planned and measured DVH. The derived γ P approximation (the " γ -slope indicator") may be clinically useful in some practical cases of radiotherapy plan QA. CONCLUSIONS In formal terms, there cannot be any correlation between γ P and any common DVH-calculated patient-specific measures, with respect to PTV or OAR. However, as demonstrated analytically and further confirmed in our simulation studies, the γ P approximation derived in this study (the " γ -slope indicator") may in some cases offer a degree of correlation between γ P and the PTV and OAR DVH QA metrics in measured and planned patient-specific dose distributions-which may be potentially useful in clinical practice.
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Affiliation(s)
- Mateusz Baran
- AGH University of Science and Technology, Krakow, Poland.,Faculty of Materials Science and Physics, Cracow University of Technology, Krakow, Poland
| | - Zbisɫaw Tabor
- AGH University of Science and Technology, Krakow, Poland.,Faculty of Materials Science and Physics, Cracow University of Technology, Krakow, Poland
| | - Monika Tulik
- Maria Sklodowska-Curie National Research Institute of Oncology Krakow Branch, Krakow, Poland
| | - Damian Kabat
- Maria Sklodowska-Curie National Research Institute of Oncology Krakow Branch, Krakow, Poland
| | - Krzysztof Rzecki
- AGH University of Science and Technology, Krakow, Poland.,Faculty of Materials Science and Physics, Cracow University of Technology, Krakow, Poland
| | | | - Michael Waligórski
- Faculty of Materials Science and Physics, Cracow University of Technology, Krakow, Poland
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Hadsell CS, Lenards N, Hunzeker A, Tallhamer MJ, Hadsell MJ. The effect of measurement geometry on patient specific QA pass/fail rates for stereotactic body radiation therapy (SBRT) Plans. Med Dosim 2021; 46:389-397. [PMID: 34176732 DOI: 10.1016/j.meddos.2021.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 03/30/2021] [Accepted: 05/04/2021] [Indexed: 11/30/2022]
Abstract
Patient quality assurance (QA) is a required part of the treatment care path, and plan failure can lead to increased personnel hours or delay of treatment. The recommendation by the American Association of Physicists in Medicine is that gamma analysis be used to evaluate measured volumetric modulated arc therapy plans. Vendors have developed many different measurement geometries for patient QA devices which could yield varying pass rates when used with the recommended tolerances, normalization, and criterion. For this study, clinically treated stereotactic body radiation therapy plans were used to evaluate differences in gamma dose tolerances and sampled dose distribution complexity for centralized or peripheral measurement geometries on a cylindrical phantom. Random errors were then introduced into a subset of these plans, and the differences in pass rates between the geometries were correlated with differences in the observed mathematical differences. Finally, a single clinically relevant target coverage deviation was introduced to another subset of plans to evaluate whether a particular geometry is measurably better at identifying clinically relevant errors. It was found that centralized geometries resulted in more lenient dose tolerances and less complex sampled dose distributions compared to peripheral geometries. Pass rates were uniformly lower in the peripheral measurement geometry, and the difference in pass rates between the geometries correlated strongly with the difference in dose tolerance and weakly with the difference in the chosen complexity metrics. However, neither of the geometries were sufficiently sensitive enough to detect clinically relevant changes to target coverage when using recommended tolerances and criteria, and no statistically significant difference was found between their pass rates. Given these findings, the authors concluded that stereotactic body radiation therapy plans could fail patient QA when measured in the peripheral geometry but pass in the centralized geometry, with possibly neither having correlation to true clinical deviation.
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Affiliation(s)
- Courtney S Hadsell
- Medical Dosimetry Program at the University of Wisconsin, La Crosse, WI, USA.
| | - Nishele Lenards
- Medical Dosimetry Program at the University of Wisconsin, La Crosse, WI, USA
| | - Ashley Hunzeker
- Medical Dosimetry Program at the University of Wisconsin, La Crosse, WI, USA
| | | | - Michael J Hadsell
- Departments of Radiation Oncology, Centura Health, Centennial, CO, USA
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Rosenfeld AB, Biasi G, Petasecca M, Lerch MLF, Villani G, Feygelman V. Semiconductor dosimetry in modern external-beam radiation therapy. Phys Med Biol 2020; 65:16TR01. [PMID: 32604077 DOI: 10.1088/1361-6560/aba163] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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10
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Tulik M, Kabat D, Baran M, Kycia R, Tabor Z. Use of statistical approaches to improve the quality control of the dose delivery in radiotherapy. ACTA ACUST UNITED AC 2019; 64:145018. [DOI: 10.1088/1361-6560/ab25ab] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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11
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Biondi M, Vanzi E, De Otto G, Belmonte G, Banci Buonamici F. A correlation study between clinical dose distribution and gamma passing rates in pre-treatment Tomotherapy quality assurance. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab27a3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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12
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Kaneko A, Sumida I, Mizuno H, Isohashi F, Suzuki O, Seo Y, Otani K, Tamari K, Ogawa K. Comparison of gamma index based on dosimetric error and clinically relevant dose-volume index based on three-dimensional dose prediction in breast intensity-modulated radiation therapy. Radiat Oncol 2019; 14:36. [PMID: 30808377 PMCID: PMC6390354 DOI: 10.1186/s13014-019-1233-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 01/27/2019] [Indexed: 12/04/2022] Open
Abstract
Background Measurement-guided dose reconstruction has lately attracted significant attention because it can predict the delivered patient dose distribution. Although the treatment planning system (TPS) uses sophisticated algorithm to calculate the dose distribution, the calculation accuracy depends on the particular TPS used. This study aimed to investigate the relationship between the gamma passing rate (GPR) and the clinically relevant dose–volume index based on the predicted 3D patient dose distribution derived from two TPSs (XiO, RayStation). Methods Twenty-one breast intensity-modulated radiation therapy plans were inversely optimized using XiO. With the same plans, both TPSs calculated the planned dose distribution. We conducted per-beam measurements on the coronal plane using a 2D array detector and analyzed the difference in 2D GPRs between the measured and planned doses by commercial software. Using in-house software, we calculated the predicted 3D patient dose distribution and derived the predicted 3D GPR, the predicted per-organ 3D GPR, and the predicted clinically relevant dose–volume indices [dose–volume histogram metrics and the value of the tumor-control probability/normal tissue complication probability of the planning target volume and organs at risk]. The results derived from XiO were compared with those from RayStation. Results While the mean 2D GPRs derived from both TPSs were 98.1% (XiO) and 100% (RayStation), the mean predicted 3D GPRs of ipsilateral lung (73.3% [XiO] and 85.9% [RayStation]; p < 0.001) had no correlation with 2D GPRs under the 3% global/3 mm criterion. Besides, this significant difference in terms of referenced TPS between XiO and RayStation could be explained by the fact that the error of predicted V5Gy of ipsilateral lung derived from XiO (29.6%) was significantly larger than that derived from RayStation (− 0.2%; p < 0.001). Conclusions GPR is useful as a patient quality assurance to detect dosimetric errors; however, it does not necessarily contain detailed information on errors. Using the predicted clinically relevant dose–volume indices, the clinical interpretation of dosimetric errors can be obtained. We conclude that a clinically relevant dose–volume index based on the predicted 3D patient dose distribution could add to the clinical and biological considerations in the GPR, if we can guarantee the dose calculation accuracy of referenced TPS.
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Affiliation(s)
- Akari Kaneko
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan. .,Department of Radiology, Suita Tokushukai Hospital, 21-1 Senrioka-nishi, Suita, 565-0814, Osaka, Japan.
| | - Iori Sumida
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Hirokazu Mizuno
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Fumiaki Isohashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Osamu Suzuki
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Keisuke Otani
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Keisuke Tamari
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, 565-0871, Osaka, Japan
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13
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Evaluating the dosimetric consequences of MLC leaf positioning errors in dynamic IMRT treatments. JOURNAL OF RADIOTHERAPY IN PRACTICE 2019. [DOI: 10.1017/s1460396918000705] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractPurposeThe purpose of this study was to evaluate the dosimetric impact of multileaf collimator (MLC) positional errors on dynamic intensity-modulated radiotherapy (IMRT) treatments through planning simulation. Secondly the sensitivity of IMRT MatriXX device for detecting the MLC leaf positional errors was also evaluated.Materials and methodsIn this study five dynamic IMRT plans, each for brain and head–neck (HN), were retrospectively included. An in-house software was used to introduce random errors (uniform distribution between −2·0 and +2·0 mm) and systematic errors [±0·5, ±0·75, ±1·0 and ±2·0 mm (+: open MLC error and −: close MLC error)]. The error-introduced MLC files were imported into the treatment planning system and new dose distributions were calculated. Furthermore, the dose–volume histogram files of all plans were exported to in-house software for equivalent uniform dose (EUD), tumour control probability and normal tissue complication probability calculations. The error-introduced plans were also delivered on LINAC, and the planar fluences were measured by IMRT MatriXX. Further, 3%/3 mm and 2%/2 mm γ-criteria were used for analysis.ResultsIn planning simulation study, the impact of random errors was negligible and ΔEUD was <0·5±0·7%, for both brain and HN. The impact of systematic errors was substantial, and on average, the maximum change in EUD for systematic errors (close 2 mm) was −10·7±3·1% for brain and −15·5±2·6% for HN.ConclusionsIt can be concluded that the acceptable systematic error was 0·4 mm for brain and 0·3 mm for HN. Furthermore, IMRT MatriXX device was able to detect the MLC errors ≥2 mm in HN and >3 mm errors in brain with 2%/2 mm γ-criteria.
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14
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Tamborra P, Martinucci E, Massafra R, Bettiol M, Capomolla C, Zagari A, Didonna V. The 3D isodose structure-based method for clinical dose distributions comparison in pretreatment patient-QA. Med Phys 2018; 46:426-436. [PMID: 30450559 DOI: 10.1002/mp.13297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 11/07/2018] [Accepted: 11/08/2018] [Indexed: 11/05/2022] Open
Abstract
INTRODUCTION Before the approval of any Intensity Modulated Radiation Therapy or Volumetric Modulated Arc Therapy treatment plan, quality assurance (QA) tests are needed to reveal potential errors such as an inaccurate calculation of the dose distribution, the failure of the record-and-verify system, or the delivery system of the linear accelerator. Currently, the method adopted to compare the measured dose distribution with the treatment planning system TPS calculated dose distribution is gamma analysis. However, gamma analysis has been shown to be ineffective for the clinical evaluation of treatment plans. We proposed and tested a new method (the isodose structures method) alternative to gamma analysis. METHOD Different errors were introduced in 33 error-free Head and Neck plans. The modified plans were recalculated using TPS software and the dose distributions obtained were compared to those of the original (error-free) plans. The comparison was performed using gamma analysis and the new method. The target was to calculate overall and organ-specific gamma passing rates as well as the overlapping ratio (OR) and volume ratio (VR) factors of the isodose structures method for each error-included plan. RESULTS Eight of the 33 plans passed both the gamma analysis and the isodose structures (IS) analysis, ten plans did not pass either of them, while 13 plans which did not pass the IS analysis, passed the gamma analysis. Two plans which did not pass gamma, passed IS analysis. Furthermore, Dose Volume Histogram (DVH) metrics could not detect the low agreement between the dose distributions of two error-free plans and the respective modified plans. In this case, the IS analysis also allowed us to detect clinically meaningful differences between measured and TPS dose distributions. CONCLUSIONS The IS method analysis clearly showed a high efficiency in detecting clinically relevant differences between TPS and measured dose distributions not seen in gamma analysis and in DVH-based metrics. Therefore, IS analysis proved to be a valid tool, alternative to gamma analysis for dose comparison in patient-specific QA test.
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Affiliation(s)
- Pasquale Tamborra
- Department of Medical Physics, IRCCS Istituto Tumori "Giovanni Paolo II", Bari, 70124, Italy
| | - Erica Martinucci
- Department of Medical Physics, Hospital "Vito Fazzi" - Cancer Centre "Giovanni Paolo II", Lecce, 70130, Italy
| | - Raffaella Massafra
- Department of Medical Physics, IRCCS Istituto Tumori "Giovanni Paolo II", Bari, 70124, Italy
| | - Marco Bettiol
- Department of Medical Physics, IRCCS Istituto Tumori "Giovanni Paolo II", Bari, 70124, Italy
| | - Caterina Capomolla
- Department of Medical Physics, Hospital "Vito Fazzi" - Cancer Centre "Giovanni Paolo II", Lecce, 70130, Italy
| | - Annarita Zagari
- Department of Medical Physics, Hospital "Vito Fazzi" - Cancer Centre "Giovanni Paolo II", Lecce, 70130, Italy
| | - Vittorio Didonna
- Department of Medical Physics, IRCCS Istituto Tumori "Giovanni Paolo II", Bari, 70124, Italy
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15
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Kim DS, Kim S, Kang SH, Kim TH, Park SH, Kim KH, Cho MS, Shin DS, Noh YY, Chung JB, Suh TS. To propose adding index of achievement (IOA) to IMRT QA process. Radiat Oncol 2018; 13:112. [PMID: 29903025 PMCID: PMC6003087 DOI: 10.1186/s13014-018-1055-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 05/28/2018] [Indexed: 11/28/2022] Open
Abstract
Background In intensity modulated radiation therapy (IMRT) quality assurance (QA), evaluation of QA result using a pass/non-pass strategy under an acceptance criterion often suffers from lack of information on how good the plan is in absolute manner. In this study, we suggested adding an index system, previously developed for dose painting technique, to current IMRT QA process for better understanding of QA result. Methods The index system consists of three indices, index of achievement (IOA), index of hotness (IOH) and index of coldness (IOC). As indicated by its name, IOA does measure the level of agreement. IOH and IOC, on the other hand, measure the magnitude of overdose and underdose, respectively. A systematic analysis was performed with three 1-dimensional hypothetical dose distributions to investigate the characteristics of the index system. The feasibility of the system was also assessed with clinical volumetric modulated arc therapy (VMAT) QA cases from 8 head & neck and 5 prostate patients. In both simulation studies, certain amount of errors was intentionally induced to each dose distribution. Furthermore, we applied the proposed system to compare calculated with actual measured data for a total of 60 patients (30 head & neck and 30 prostate cases). QA analysis was made using both the index system and gamma method, and results were compared. Results While the gamma evaluation showed limited sensitivity in evaluating QA result depending on the level of tolerance criteria used, the proposed indices tended to better distinguish plans in terms of the amount of errors. Hotness and coldness of prescribed dose in the plan could be evaluated quantitatively by the indices. Conclusions The proposed index system provides information with which IMRT QA result would be better evaluated, especially when gamma pass rates are identical or similar among multiple plans. In addition, the independency of the index system on acceptance criteria would help making clear communications among readers of published articles and researchers in multi-institutional studies.
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Affiliation(s)
- Dong-Su Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Siyong Kim
- Department of Radiation Oncology, Virginia Commonwealth University, 401 College Street, Richmond, VA, 23298-0058, USA.
| | - Seong-Hee Kang
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea.,Department of Radiation Oncology, Seoul National University Bundang Hospital, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Tae-Ho Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - So-Hyun Park
- Department of Radiation Oncology, Jeju National University Hospital, 15, Aran 13-gil, Jeju-si, Jeju-do, 63241, South Korea
| | - Kyeong-Hyeon Kim
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Min-Seok Cho
- Department of Radiation Oncology, Asan Medical Center, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 05505, South Korea
| | - Dong-Seok Shin
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea
| | - Yu-Yun Noh
- Department of Radiation Oncology, Eulji University Hospital, 95, Dunsanseo-ro, Seo-gu, Daejeon, 35233, South Korea
| | - Jin-Beom Chung
- Department of Radiation Oncology, Seoul National University Bundang Hospital, Gumi-ro 173 beon-gil, Bundang-gu, Seongnam-si, Gyeonggi-do, 13620, South Korea
| | - Tae Suk Suh
- Department of Biomedical Engineering and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, 222. Banpo-daero, Seocho-gu, Seoul, 06591, South Korea.
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16
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Miften M, Olch A, Mihailidis D, Moran J, Pawlicki T, Molineu A, Li H, Wijesooriya K, Shi J, Xia P, Papanikolaou N, Low DA. Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218. Med Phys 2018; 45:e53-e83. [DOI: 10.1002/mp.12810] [Citation(s) in RCA: 373] [Impact Index Per Article: 62.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Revised: 12/10/2017] [Accepted: 01/11/2018] [Indexed: 11/07/2022] Open
Affiliation(s)
- Moyed Miften
- Department of Radiation Oncology; University of Colorado School of Medicine; Aurora CO USA
| | - Arthur Olch
- Department of Radiation Oncology; University of Southern California and Radiation Oncology Program; Childrens Hospital of Los Angeles; Los Angeles CA USA
| | - Dimitris Mihailidis
- Department of Radiation Oncology; University of Pennsylvania; Perelman Center for Advanced Medicine; Philadelphia PA USA
| | - Jean Moran
- Department of Radiation Oncology; University of Michigan; Ann Arbor MI USA
| | - Todd Pawlicki
- Department of Radiation Oncology; University of California San Diego; La Jolla CA USA
| | - Andrea Molineu
- Radiological Physics Center; UT MD Anderson Cancer Center; Houston TX USA
| | - Harold Li
- Department of Radiation Oncology; Washington University; St. Louis MO USA
| | - Krishni Wijesooriya
- Department of Radiation Oncology; University of Virginia; Charlottesville VA USA
| | - Jie Shi
- Sun Nuclear Corporation; Melbourne FL USA
| | - Ping Xia
- Department of Radiation Oncology; The Cleveland Clinic; Cleveland OH USA
| | - Nikos Papanikolaou
- Department of Medical Physics; University of Texas Health Sciences Center; San Antonio TX USA
| | - Daniel A. Low
- Department of Radiation Oncology; University of California Los Angeles; Los Angeles CA USA
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17
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Katsuta Y, Kadoya N, Fujita Y, Shimizu E, Matsunaga K, Sawada K, Matsushita H, Majima K, Jingu K. Patient-Specific Quality Assurance Using Monte Carlo Dose Calculation and Elekta Log Files for Prostate Volumetric-Modulated Arc Therapy. Technol Cancer Res Treat 2017; 16:1220-1225. [PMID: 29334027 PMCID: PMC5762095 DOI: 10.1177/1533034617745250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Log file–based methods are attracting increasing interest owing to their ability to validate volumetric-modulated arc therapy outputs with high resolution in the leaf and gantry positions and in delivered dose. Cross-validation of these methods for comparison with measurement-based methods using the ionization chamber/ArcCHECK-3DVH software (version 3.2.0) under the same conditions of treatment anatomy and plan enables an efficient evaluation of this method. In this study, with the purpose of cross-validation, we evaluate the accuracy of a log file–based method using Elekta log files and an X-ray voxel Monte Carlo dose calculation technique in the case of leaf misalignment during prostate volumetric-modulated arc therapy. In this study, 10 prostate volumetric-modulated arc therapy plans were used. Systematic multileaf collimator leaf positional errors (±0.4 and ±0.8 mm for each single bank) were deliberately introduced into the optimized plans. Then, the delivered 3-dimensional doses to a phantom with a certain patient anatomy were estimated by our system. These doses were compared with the ionization chamber dose and the ArcCHECK-3DVH dose. For the given phantom and patient anatomy, the estimated dose strongly coincided with the ionization chamber/ArcCHECK-3DVH dose (P < .01). In addition, good agreement between the estimated dose and the ionization chamber/ArcCHECK-3DVH dose was observed. The dose estimation accuracy of our system, which combines Elekta log files and X-ray voxel Monte Carlo dose calculation, was evaluated.
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Affiliation(s)
- Yoshiyuki Katsuta
- 1 Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan.,2 Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Noriyuki Kadoya
- 2 Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yukio Fujita
- 3 Department of Radiation Oncology, Tokai University Graduate School of Medicine, Isehara, Japan
| | - Eiji Shimizu
- 1 Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan
| | - Kenichi Matsunaga
- 1 Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan
| | - Kinya Sawada
- 1 Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan
| | - Haruo Matsushita
- 2 Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kazuhiro Majima
- 1 Department of Radiology, Takeda General Hospital, Aizuwakamatsu, Japan
| | - Keiichi Jingu
- 2 Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
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18
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Kantz S, Troeller McDermott A, Söhn M, Reinhardt S, Belka C, Parodi K, Reiner M. Practical implications for the quality assurance of modulated radiation therapy techniques using point detector arrays. J Appl Clin Med Phys 2017; 18:20-31. [PMID: 28857409 PMCID: PMC5689906 DOI: 10.1002/acm2.12157] [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] [Received: 03/09/2017] [Revised: 06/02/2017] [Accepted: 06/29/2017] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Linac parameters potentially influencing the delivery quality of IMRT and VMAT plans are investigated with respect to threshold ranges, consequently to be considered in a linac based quality assurance procedure. Three commercially available 2D arrays are used to further investigate the influence of the measurement device. METHODS Using three commercially available 2D arrays (Mx: MatriXXevolution , Oc: Octavius1500 , Mc: MapCHECK2), simple static measurements, measurements for MLC characterization and dynamic interplay of gantry movement, MLC movement and variable dose rate were performed. The results were evaluated with respect to each single array as well as among each other. RESULTS Simple static measurements showed different array responses to dose, dose rate and profile homogeneity and revealed instabilities in dose delivery and profile shape during linac ramp up. Using the sweeping gap test, all arrays were able to detect small leaf misalignments down to ±0.1 mm, but this test also demonstrated up to 15% dose deviation due to profile instabilities and fast accelerating leaves during linac ramp up. Tests including gantry rotation showed different stability of gantry mounts for each array. Including gantry movement and dose rate variability, differences compared to static delivery were smaller compared to dose differences when simultaneously controling interplay of gantry movement, leaf movement and dose rate variability. CONCLUSION Linac based QA is feasible with the tested commercially available 2D arrays. Limitations of each array and the linac ramp up characteristics should be carefully considered during individual plan generation and regularly checked in linac QA. Especially the dose and dose profile during linac ramp up should be checked regularly, as well as MLC positioning accuracy using a sweeping gap test. Additionally, dynamic interplay tests including various gantry rotation speeds and angles, various leaf speeds and various dose rates should be included.
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Affiliation(s)
- Steffi Kantz
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - Almut Troeller McDermott
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany.,Department of Radiation Oncology, Beaumont Health, Royal Oak, MI, USA
| | - Matthias Söhn
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - Sabine Reinhardt
- Faculty of Physics, Department of Medical Physics, LMU Munich, Munich, Germany
| | - Claus Belka
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
| | - Katia Parodi
- Faculty of Physics, Department of Medical Physics, LMU Munich, Munich, Germany
| | - Michael Reiner
- Department of Radiation Oncology, University Hospital, LMU Munich, Munich, Germany
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19
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Paudel NR, Narayanasamy G, Han EY, Penagaricano J, Mavroidis P, Zhang X, Pyakuryal A, Kim D, Liang X, Morrill S. Dosimetric and radiobiological comparison for quality assurance of IMRT and VMAT plans. J Appl Clin Med Phys 2017; 18:237-244. [PMID: 28771941 PMCID: PMC5874955 DOI: 10.1002/acm2.12145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Revised: 06/16/2017] [Accepted: 06/22/2017] [Indexed: 11/24/2022] Open
Abstract
Introduction The gamma analysis used for quality assurance of a complex radiotherapy plan examines the dosimetric equivalence between planned and measured dose distributions within some tolerance. This study explores whether the dosimetric difference is correlated with any radiobiological difference between delivered and planned dose. Methods VMAT or IMRT plans optimized for 14 cancer patients were calculated and delivered to a QA device. Measured dose was compared against planned dose using 2‐D gamma analysis. Dose volume histograms (for various patient structures) obtained by interpolating measured data were compared against the planned ones using a 3‐D gamma analysis. Dose volume histograms were used in the Poisson model to calculate tumor control probability for the treatment targets and in the Sigmoid dose–response model to calculate normal tissue complication probability for the organs at risk. Results Differences in measured and planned dosimetric data for the patient plans passing at ≥94.9% rate at 3%/3 mm criteria are not statistically significant. Average ± standard deviation tumor control probabilities based on measured and planned data are 65.8±4.0% and 67.8±4.1% for head and neck, and 71.9±2.7% and 73.3±3.1% for lung plans, respectively. The differences in tumor control probabilities obtained from measured and planned dose are statistically insignificant. However, the differences in normal tissue complication probabilities for larynx, lungs‐GTV, heart, and cord are statistically significant for the patient plans meeting ≥94.9% passing criterion at 3%/3 mm. Conclusion A ≥90% gamma passing criterion at 3%/3 mm cannot assure the radiobiological equivalence between planned and delivered dose. These results agree with the published literature demonstrating the inadequacy of the criterion for dosimetric QA and suggest for a tighter tolerance.
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Affiliation(s)
- Nava Raj Paudel
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
- Department of Radiation OncologyUPMC SusquehannaWilliamsportPAUSA
| | - Ganesh Narayanasamy
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
| | - Eun Young Han
- Department of Radiation PhysicsThe University of Texas MD Anderson Cancer CenterHoustonTexasUSA
| | - Jose Penagaricano
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
| | | | - Xin Zhang
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
| | | | - Dongwook Kim
- Department of Radiation OncologyKyung Hee University Hospital at GangdongSeoulKorea
| | - Xiaoying Liang
- Department of Radiation OncologyUniversity of FloridaGainesvilleFLUSA
| | - Steven Morrill
- Department of Radiation OncologyUniversity of Arkansas for Medical SciencesLittle RockARUSA
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20
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The sensitivity of gamma index analysis to detect multileaf collimator (MLC) positioning errors using Varian TrueBeam EPID and ArcCHECK for patient-specific prostate volumetric-modulated arc therapy (VMAT) quality assurance. JOURNAL OF RADIOTHERAPY IN PRACTICE 2017. [DOI: 10.1017/s1460396917000425] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractBackgroundDue to the increased degree of modulation and complexity of volumetric-modulated arc therapy (VMAT) plans, it is necessary to have a pre-treatment patient-specific quality assurance (QA) programme. The gamma index is commonly used to quantitatively compare two dose distributions. In this study we investigated the sensitivity of single- and multi-gamma criteria techniques to detect multileaf collimator (MLC) positioning errors using the Varian TrueBeam Electronic Portal Imaging DeviceTM (EPID) dosimetry and the ArcCHECKTM device.Materials and methodsAll active MLC positions of seven intact prostate patients VMAT plans were randomly changed with a mean value of 0.25, 0.5, 1 and 2 mm and a standard deviation of 0.1 mm on 25, 50, 75 and 100% of the control points. The change in gamma passing rates of six gamma criteria of 3%/3 mm, 3%/2 mm, 3%/1 mm, 2%/2 mm, 2%/1 mm and 1%/1 mm were analysed individually (single-gamma criterion) and as a group (multi-gamma criteria) as a function of the simulated errors. We used the improved and global gamma calculation algorithms with a low dose threshold of 10% in the EPID and ArcCHECK software, respectively. The changes in the planning target volume dose distributions and the organs at risk due to the MLC positioning errors were also studied.ResultsWhen 25, 50, 75 and 100% of the control points were modified by the introduction of the simulated errors, the smallest detectable errors with the EPID were 2, 1, 0.5 and 0.5 mm, respectively, using the multi-gamma criteria technique. Similarly for the single-gamma criteria technique errors as small as 2, 1, 1 and 1 mm applied to 25, 50, 75 and 100% of the control points, respectively, were detectable using a 2%/2 mm criterion. However, the smallest detectable errors with the ArcCHECK when using the multi-gamma criteria technique were 2, 2 and 1 mm when MLC errors were applied on 50, 75 and 100% of the control points. When only 25% of the control points were affected the ArcCHECK were unable to detect any of the errors applied. No noticeable difference was observed in the sensitivity using the single- or the multi-gamma criteria techniques with the ArcCHECK.ConclusionThe Varian TrueBeam EPID dosimetry shows a higher sensitivity in detecting MLC positioning errors compared with the ArcCHECK regardless of using the single- or the multi-gamma criteria techniques. Higher sensitivity was observed using the multi-gamma criteria technique compared with the single-criterion technique when using the EPID.
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21
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Gardner SJ, Lu S, Liu C, Wen N, Chetty IJ. Tuning of AcurosXB source size setting for small intracranial targets. J Appl Clin Med Phys 2017; 18:170-181. [PMID: 28470819 PMCID: PMC5689841 DOI: 10.1002/acm2.12091] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/13/2017] [Accepted: 03/17/2017] [Indexed: 11/16/2022] Open
Abstract
This study details a method to evaluate the source size selection for small field intracranial stereotactic radiosurgery (SRS) deliveries in Eclipse treatment planning system (TPS) for AcurosXB dose calculation algorithm. Our method uses end‐to‐end dosimetric data to evaluate a total of five source size selections (0.50 mm, 0.75 mm, 1.00 mm, 1.25 mm, and 1.50 mm). The dosimetric leaf gap (DLG) was varied in this analysis (three DLG values were tested for each scenario). We also tested two MLC leaf designs (standard and high‐definition MLC) and two delivery types for intracranial SRS (volumetric modulated arc therapy [VMAT] and dynamic conformal arc [DCA]). Thus, a total of 10 VMAT plans and 10 DCA plans were tested for each machine type (TrueBeam [standard MLC] and Edge [high‐definition MLC]). Each plan was mapped to a solid water phantom and dose was calculated with each iteration of source size and DLG value (15 total dose calculations for each plan). To measure the dose, Gafchromic film was placed in the coronal plane of the solid water phantom at isocenter. The phantom was localized via on‐board CBCT and the plans were delivered at planned gantry, collimator, and couch angles. The planned and measured film dose was compared using Gamma (3.0%, 0.3 mm) criteria. The vendor‐recommended 1.00 mm source size was suitable for TrueBeam planning (both VMAT and DCA planning) and Edge DCA planning. However, for Edge VMAT planning, the 0.50 mm source size yielded the highest passing rates. The difference in dose calculation among the source size variations manifested primarily in two regions of the dose calculation: (1) the shoulder of the high‐dose region, and (2) for small targets (volume ≤ 0.30 cc), in the central portion of the high‐dose region. Selection of a larger than optimal source size can result in increased blurring of the shoulder for all target volume sizes tested, and can result in central axis dose discrepancies in excess of 10% for target volumes sizes ≤ 0.30 cc. Our results indicate a need for evaluation of the source size when AcurosXB is used to model intracranial SRS delivery, and our methods represent a feasible process for many clinics to perform tuning of the AcurosXB source size parameter.
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Affiliation(s)
- Stephen J Gardner
- Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA
| | - Siming Lu
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, Commack, NY, USA
| | - Chang Liu
- Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA
| | - Ning Wen
- Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA
| | - Indrin J Chetty
- Department of Radiation Oncology, Henry Ford Health System, Detroit, MI, USA
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McCowan PM, Asuni G, van Beek T, van Uytven E, Kujanpaa K, McCurdy BMC. A model-based 3D patient-specific pre-treatment QA method for VMAT using the EPID. Phys Med Biol 2017; 62:1600-1612. [PMID: 28079525 DOI: 10.1088/1361-6560/aa590a] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
This study reports the development and validation of a model-based, 3D patient dose reconstruction method for pre-treatment quality assurance using EPID images. The method is also investigated for sensitivity to potential MLC delivery errors. Each cine-mode EPID image acquired during plan delivery was processed using a previously developed back-projection dose reconstruction model providing a 3D dose estimate on the CT simulation data. Validation was carried out using 24 SBRT-VMAT patient plans by comparing: (1) ion chamber point dose measurements in a solid water phantom, (2) the treatment planning system (TPS) predicted 3D dose to the EPID reconstructed 3D dose in a solid water phantom, and (3) the TPS predicted 3D dose to the EPID and our forward predicted reconstructed 3D dose in the patient (CT data). AAA and AcurosXB were used for TPS predictions. Dose distributions were compared using 3%/3 mm (95% tolerance) and 2%/2 mm (90% tolerance) γ-tests in the planning target volume (PTV) and 20% dose volumes. The average percentage point dose differences between the ion chamber and the EPID, AcurosXB, and AAA were 0.73 ± 1.25%, 0.38 ± 0.96% and 1.06 ± 1.34% respectively. For the patient (CT) dose comparisons, seven (3%/3 mm) and nine (2%/2 mm) plans failed the EPID versus AAA. All plans passed the EPID versus Acuros XB and the EPID versus forward model γ-comparisons. Four types of MLC sensitive errors (opening, shifting, stuck, and retracting), of varying magnitude (0.2, 0.5, 1.0, 2.0 mm), were introduced into six different SBRT-VMAT plans. γ-comparisons of the erroneous EPID dose and original predicted dose were carried out using the same criteria as above. For all plans, the sensitivity testing using a 3%/3 mm γ-test in the PTV successfully determined MLC errors on the order of 1.0 mm, except for the single leaf retraction-type error. A 2%/2 mm criteria produced similar results with two more additional detected errors.
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Affiliation(s)
- P M McCowan
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada. Medical Physics Department, CancerCare Manitoba, 675 McDermot Ave., Winnipeg, Manitoba, R3E 0V9, Canada
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Liang B, Liu B, Zhou F, Yin FF, Wu Q. Comparisons of volumetric modulated arc therapy (VMAT) quality assurance (QA) systems: sensitivity analysis to machine errors. Radiat Oncol 2016; 11:146. [PMID: 27821135 PMCID: PMC5100111 DOI: 10.1186/s13014-016-0725-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 11/02/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In volumetric modulated arc therapy (VMAT), gantry angles, dose rate and the MLC positions vary with the radiation delivery. The quality assurance (QA) system should be able to catch the planning and machine errors. The aim of this study was to investigate the sensitivity of three VMAT QA systems to machine errors. METHODS Several types of potential linac machine errors unique to VMAT delivery were simulated in sinusoidal function of gantry angle, including gantry angle itself, MLC position and linac output. Two commercial QA systems, ArcCheck and Delta4, and an in-house developed EPID technique were compared in this study. Fifteen full arcs from head and neck plans were selected and modified to include five magnitudes of each type of error, resulting in measurements and γ analyses of 240 arcs on each system. Both qualitative and quantitative comparisons were performed using receiver operating characteristic (ROC), γ pass rate gradient, and overlap histogram methods. RESULTS In ROC analysis, the area under curve (AUC) represents the sensitivity and increases with the error magnitude. Using the criteria of 2 %/2 mm/2° (angle to agreement, ATA, only for EPID) and keeping AUC > 0.95, the minimum error detectable of ArcCheck, Delta4 and EPID are (2, 3, 3)° in gantry angle and (4, 2, 3) mm in MLC positions for the head and neck plans. No system is sensitive to the simulated output error, the AUC values were all below 0.70 even with 5 % output error. The γ gradient for gantry angle, MLC position and output errors are (-5.1, -2.6, -3.6)%/°, (-2.6, -7.1, -3.3)%/mm and (-0.2, -0.2, -0.3)%/% for ArcCheck, Delta4 and EPID, respectively. Therefore, these two analyses are consistent and support the same conclusion. The ATA parameter in EPID technique can be adjusted to tune its sensitivity. CONCLUSIONS We found that ArcCheck is more sensitive to gantry angle error and Delta4 is more sensitive to MLC position error. All three systems are not sensitive to the simulated output error. With additional analysis parameter, the EPID technique can be tuned to have optimal sensitivity and is able to perform QA for full field size with highest resolution. In addition, ROC analysis avoids the choice of γ pass rate threshold and is more robust compared with other analysis methods.
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Affiliation(s)
- Bin Liang
- Image Processing Center, Beihang University, Beijing, 100191, People's Republic of China
| | - Bo Liu
- Image Processing Center, Beihang University, Beijing, 100191, People's Republic of China.
| | - Fugen Zhou
- Image Processing Center, Beihang University, Beijing, 100191, People's Republic of China
| | - Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, PO Box 3295, Durham, NC, 27710, USA
| | - Qiuwen Wu
- Department of Radiation Oncology, Duke University Medical Center, PO Box 3295, Durham, NC, 27710, USA.
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24
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Yoon MS, Jeong JU, Nam TK, Ahn SJ, Chung WK, Song JY. Evaluation of Dose Distribution in Intensity Modulated Radiosurgery for Lung Cancer under Condition of Respiratory Motion. PLoS One 2016; 11:e0163112. [PMID: 27648949 PMCID: PMC5029809 DOI: 10.1371/journal.pone.0163112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/04/2016] [Indexed: 11/26/2022] Open
Abstract
The dose of a real tumor target volume and surrounding organs at risk (OARs) under the effect of respiratory motion was calculated for a lung tumor plan, based on the target volume covering the whole tumor motion range for intensity modulated radiosurgery (IMRS). Two types of IMRS plans based on simulated respiratory motion were designed using humanoid and dynamic phantoms. Delivery quality assurance (DQA) was performed using ArcCHECK and MapCHECK2 for several moving conditions of the tumor and the real dose inside the humanoid phantom was evaluated using the 3DVH program. This evaluated dose in the tumor target and OAR using the 3DVH program was higher than the calculated dose in the plan, and a greater difference was seen for the RapidArc treatment than for the standard intensity modulated radiation therapy (IMRT) with fixed gantry angle beams. The results of this study show that for IMRS plans based on target volume, including the whole tumor motion range, tighter constraints of the OAR should be considered in the optimization process. The method devised in this study can be applied effectively to analyze the dose distribution in the real volume of tumor target and OARs in IMRT plans targeting the whole tumor motion range.
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Affiliation(s)
- Mee Sun Yoon
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
| | - Jae-Uk Jeong
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
| | - Taek-Keun Nam
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
| | - Sung-Ja Ahn
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
| | - Woong-Ki Chung
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
| | - Ju-Young Song
- Department of Radiation Oncology, Chonnam National University Medical School, Gwangju, Korea
- * E-mail:
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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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26
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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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27
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Gamma index comparison of three VMAT QA systems and evaluation of their sensitivity to delivery errors. Phys Med 2015; 31:720-5. [DOI: 10.1016/j.ejmp.2015.05.016] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 05/18/2015] [Accepted: 05/30/2015] [Indexed: 11/19/2022] Open
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Stojadinovic S, Ouyang L, Gu X, Pompoš A, Bao Q, Solberg TD. Breaking bad IMRT QA practice. J Appl Clin Med Phys 2015; 16:5242. [PMID: 26103484 PMCID: PMC5690124 DOI: 10.1120/jacmp.v16i3.5242] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 12/22/2014] [Accepted: 12/17/2014] [Indexed: 11/23/2022] Open
Abstract
Agreement between planned and delivered dose distributions for patient-specific quality assurance in routine clinical practice is predominantly assessed utilizing the gamma index method. Several reports, however, fundamentally question current IMRT QA practice due to poor sensitivity and specificity of the standard gamma index implementation. An alternative is to employ dose volume histogram (DVH)-based metrics. An analysis based on the AAPM TG 53 and ESTRO booklet No.7 recommendations for QA of treatment planning systems reveals deficiencies in the current "state of the art" IMRT QA, no matter which metric is selected. The set of IMRT benchmark plans were planned, delivered, and analyzed by following guidance of the AAPM TG 119 report. The recommended point dose and planar dose measurements were obtained using a PinPoint ionization chamber, EDR2 radiographic film, and a 2D ionization chamber array. Gamma index criteria {3% (global), 3 mm} and {3% (local), 3 mm} were used to assess the agreement between calculated and delivered planar dose distributions. Next, the AAPM TG 53 and ESTRO booklet No.7 recommendations were followed by dividing dose distributions into four distinct regions: the high-dose (HD) or umbra region, the high-gradient (HG) or penumbra region, the medium-dose (MD) region, and the low-dose (LD) region. A different gamma passing criteria was defined for each region, i.e., a "divide and conquer" (D&C) gamma method was utilized. The D&C gamma analysis was subsequently tested on 50 datasets of previously treated patients. Measured point dose and planar dose distributions compared favorably with TG 119 benchmark data. For all complex tests, the percentage of points passing the conventional {3% (global), 3 mm} gamma criteria was 97.2% ± 3.2% and 95.7% ± 1.2% for film and 2D ionization chamber array, respectively. By dividing 2D ionization chamber array dose measurements into regions and applying 3mm isodose point distance and variable local point dose difference criteria of 7%, 15%, 25%, and 40% for HD, HG, MD, and LD regions, respectively, a 93.4% ± 2.3% gamma passing rate was obtained. Identical criteria applied using the D&C gamma technique on 50 clinical treatment plans resulted in a 97.9% ± 2.3% gamma passing score. Based on the TG 119 standard, meeting or exceeding the benchmark results would indicate an exemplary IMRT QA program. In contrast to TG 119 analysis, a different scrutiny on the same set of data, which follows the AAPM TG 53 and ESTRO booklet No.7 guidelines, reveals a much poorer agreement between calculated and measured dose distributions with large local point dose differences within different dose regions. This observation may challenge the conventional wisdom that an IMRT QA program is producing acceptable results.
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Louwe RJW, Wendling M, Monshouwer R, Satherley T, Day RA, Greig L. Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT a). Med Phys 2015; 42:1625-39. [PMID: 25832053 DOI: 10.1118/1.4914395] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Affiliation(s)
- Robert J W Louwe
- Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242, New Zealand
| | - Markus Wendling
- Department of Radiation Oncology, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands
| | - René Monshouwer
- Department of Radiation Oncology, Radboud University Medical Center, Nijmegen 6500 HB, The Netherlands
| | - Thomas Satherley
- Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242, New Zealand
| | - Rebecca A Day
- Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242, New Zealand
| | - Lynne Greig
- Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242, New Zealand
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