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Sun W, Chen K, Li Y, Xia W, Dong L, Shi Y, Ge C, Yang X, Wang L, Wang H. Optimization of collimator angles in dual-arc volumetric modulated arc therapy planning for whole-brain radiotherapy with hippocampus and inner ear sparing. Sci Rep 2021; 11:19035. [PMID: 34561504 PMCID: PMC8463591 DOI: 10.1038/s41598-021-98530-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 09/03/2021] [Indexed: 11/29/2022] Open
Abstract
To optimize the collimator angles in dual-arc volumetric modulated arc therapy (VMAT) plans for whole-brain radiotherapy with hippocampus and inner ear sparing (HIS-WBRT). Two sets of dual-arc VMAT plans were generated for 13 small-cell lung cancer patients: (1) The collimator angles of arcs 1 and 2 (θ1/θ2) were 350°/10°, 350°/30°, 350°/45°, 350°/60°, and 350°/80°, i.e., the intersection angle of θ1 and θ2 (Δθ) increased. (2) θ1/θ2 were 280°/10°, 300°/30°, 315°/45°, 330°/60°, and 350°/80°, i.e., Δθ = 90°. The conformity index (CI), homogeneity index (HI), monitor units (MUs), and dosimetric parameters of organs-at-risk were analyzed. Quality assurance for Δθ = 90° plans was performed. With Δθ increasing towards 90°, a significant improvement was observed for most parameters. In 350°/80° plans compared with 350°/10° ones, CI and HI were improved by 1.1% and 25.2%, respectively; MUs were reduced by 16.2%; minimum, maximum, and mean doses (D100%, Dmax, and Dmean, respectively) to the hippocampus were reduced by 5.5%, 6.3%, and 5.4%, respectively; Dmean to the inner ear and eye were reduced by 0.7% and 5.1%, respectively. With Δθ kept at 90°, the plan quality was not significantly affected by θ1/θ2 combinations. The gamma-index passing rates in 280°/10° and 350°/80° plans were relatively lower compared with the other Δθ = 90° plans. Δθ showed a significant effect on dual-arc VMAT plans for HIS-WBRT. With Δθ approaching 90°, the plan quality exhibited a nearly continuous improvement, whereas with Δθ = 90°, the effect of θ1/θ2 combination was insignificant.
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Affiliation(s)
- Wuji Sun
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Kunzhi Chen
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Yu Li
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Wenming Xia
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Lihua Dong
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
- Jilin Provincial Key Laboratory of Radiation Oncology and Therapy, Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
- NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun, 130021, China
| | - Yinghua Shi
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Chao Ge
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Xu Yang
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Libo Wang
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China
| | - Huidong Wang
- Department of Radiation Oncology and Therapy, The First Hospital of Jilin University, Changchun, 130021, China.
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Su H, Zhao M, Zhang J, Dai Z. Dosimetric effects related to collimator angle optimization in intensity‐modulated radiotherapy planning for gastric cancer. PRECISION RADIATION ONCOLOGY 2021. [DOI: 10.1002/pro6.1108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Huan‐fan Su
- Department of Medical Imaging Jiangxi Medical College Shangrao China
| | - Man Zhao
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Shenzhen China
| | - Jun Zhang
- Department of Radiotherapy Zhongnan Hospital of Wuhan University Wuhan China
| | - Zhi‐tao Dai
- Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital Chinese Academy of Medical Sciences and Peking Union Medical College Shenzhen China
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Sang Y, Shan G, Shao K, Hu F, Liu T. Dosimetric effect of different isocenter for nasopharyngeal carcinoma with volumetric modulated arc therapy. PRECISION RADIATION ONCOLOGY 2019. [DOI: 10.1002/pro6.1079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Affiliation(s)
- Yong Sang
- Department of Radiation PhysicsZhejiang Cancer Hospital Hangzhou Zhejiang China
- Key Laboratory of Radiation Oncology in Zhejiang Province Hangzhou Zhejiang China
| | - Guoping Shan
- Department of Radiation PhysicsZhejiang Cancer Hospital Hangzhou Zhejiang China
- Key Laboratory of Radiation Oncology in Zhejiang Province Hangzhou Zhejiang China
| | - Kainan Shao
- Department of Radiation PhysicsZhejiang Cancer Hospital Hangzhou Zhejiang China
- Key Laboratory of Radiation Oncology in Zhejiang Province Hangzhou Zhejiang China
| | - Fujun Hu
- Key Laboratory of Radiation Oncology in Zhejiang Province Hangzhou Zhejiang China
- Department of Radiation OncologyZhejiang Cancer Hospital Hangzhou Zhejiang China
| | - Tongxing Liu
- Key Laboratory of Radiation Oncology in Zhejiang Province Hangzhou Zhejiang China
- Department of Radiation OncologyZhejiang Cancer Hospital Hangzhou Zhejiang China
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Murtaza G, Mehmood S, Rasul S, Murtaza I, Khan EU. Dosimetric effect of limited aperture multileaf collimator on VMAT plan quality: A study of prostate and head-and-neck cancers. Rep Pract Oncol Radiother 2018; 23:189-198. [PMID: 29760593 DOI: 10.1016/j.rpor.2018.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/29/2017] [Accepted: 02/16/2018] [Indexed: 12/25/2022] Open
Abstract
AIM The aim of study was to evaluate the dosimetric effect of collimator-rotation on VMAT plan quality, when using limited aperture multileaf collimator of Elekta Beam Modulator™ providing a maximum aperture of 21 cm × 16 cm. BACKGROUND The increased use of VMAT technique to deliver IMRT from conventional to very specialized treatments present a challenge in plan optimization. In this study VMAT plans were optimized for prostate and head and neck cancers using Elekta Beam-ModulatorTM, whereas previous studies were reported for conventional Linac aperture. MATERIALS AND METHODS VMAT plans for nine of each prostate and head-and-neck cancer patients were produced using the 6 MV photon beam for Elekta-SynergyS® Linac using Pinnacle3 treatment planning system. Single arc, dual arc and two combined independent-single arcs were optimized for collimator angles (C) 0°, 90° and 0°-90° (0°-90°; i.e. the first-arc was assigned C0° and second-arc was assigned C90°). A treatment plan comparison was performed among C0°, C90° and C(0°-90°) for single-arc dual-arc and two independent-single-arcs VMAT techniques to evaluate the influence of extreme collimator rotations (C0° and 90°) on VMAT plan quality. Plan evaluation criteria included the target coverage, conformity index, homogeneity index and doses to organs at risk. A 'two-sided student t-test' (p ≤ 0.05) was used to determine if there was a significant difference in dose volume indices of plans. RESULTS For both prostate and head-and-neck, plan quality at collimator angles C0° and C(0°-90°) was clinically acceptable for all VMAT-techniques, except SA for head-and-neck. Poorer target coverage, higher normal tissue doses and significant p-values were observed for collimator angle 90° when compared with C0° and C(0°-90°). CONCLUSIONS A collimator rotation of 0° provided significantly better target coverage and sparing of organs-at-risk than a collimator rotation of 90° for all VMAT techniques.
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Affiliation(s)
- Ghulam Murtaza
- School of Health Sciences, University of Management and Technology, Lahore, Pakistan
| | - Shahid Mehmood
- Medical Physics, Combined Military Hospital, Rawalpindi, Pakistan
| | - Shahid Rasul
- Oncology Department, Combined Military Hospital, Rawalpindi, Pakistan
| | - Imran Murtaza
- Physics Department, International Islamic University, Islamabad, Pakistan
| | - Ehsan Ullah Khan
- Physics Department, International Islamic University, Islamabad, Pakistan
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Wang K, Meng H, Chen J, Zhang W, Feng Y. Plan quality and robustness in field junction region for craniospinal irradiation with VMAT. Phys Med 2018; 48:21-26. [DOI: 10.1016/j.ejmp.2018.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 03/02/2018] [Accepted: 03/11/2018] [Indexed: 02/05/2023] Open
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Peterlin P, Stanič K, Méndez I, Strojnik A. Treating lung cancer with dynamic conformal arc therapy: a dosimetric study. Radiat Oncol 2017; 12:93. [PMID: 28578699 PMCID: PMC5457634 DOI: 10.1186/s13014-017-0823-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 05/16/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Lung cancer patients are often in poor physical condition, and a shorter treatment time would reduce their discomfort. Dynamic conformal arc therapy (DCAT) offers a shorter treatment time than conventional 3D conformal radiotherapy (3D CRT) and is usually available even in departments without inverse planning possibilities. We examined its suitability as a treatment modality for lung cancer patients. METHODS On a cohort of 35 lung cancer patients, relevant dosimetric parameters were compared in respective DCAT and 3D CRT treatment plans. Radiochromic film dosimetry in an anthropomorphic phantom was used to compare both DCAT and 3D CRT dose distributions against their planned counterparts. RESULTS In comparison with their 3D CRT counterparts, DCAT plans equal or exceed the agreement between the calculated dose and the dose measured using film dosimetry. In dosimetric comparison, DCAT performed significantly better than 3D CRT in dose conformity to PTV and the number of monitor units used per plan, and significantly worse in dose homogeneity, mean lung dose and lung volume exposed to 5 Gy or more (V5Gy). No significant difference was found in the V20Gy value to lung, dose to 1 cm3 of spinal cord, and the mean dose to oesophagus. Improvements in V20Gy and V5Gy were found to be negatively correlated. DCAT plans differ from 3D CRT by exhibiting a moderate negative correlation between target volume sphericity and dose homogeneity. CONCLUSIONS With respect to the agreement between the planned and the irradiated dose distribution, DCAT appears at least as reliable as 3D CRT. In specific conditions concerning the patient anatomy and treatment prescription, DCAT may yield more favourable dosimetric parameters. On average, however, conventional 3D CRT usually obtains better dosimetric parameters. We can thus only recommend DCAT as a complementary technique to the conventional 3D CRT.
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Affiliation(s)
- Primož Peterlin
- Institute of Oncology Ljubljana, Zaloška 2, Ljubljana, SI-1000, Slovenia.
| | - Karmen Stanič
- Institute of Oncology Ljubljana, Zaloška 2, Ljubljana, SI-1000, Slovenia
| | - Ignasi Méndez
- Institute of Oncology Ljubljana, Zaloška 2, Ljubljana, SI-1000, Slovenia
| | - Andrej Strojnik
- Institute of Oncology Ljubljana, Zaloška 2, Ljubljana, SI-1000, Slovenia
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Plan robustness in field junction region from arcs with different patient orientation in total marrow irradiation with VMAT. Phys Med 2015; 31:677-82. [DOI: 10.1016/j.ejmp.2015.05.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 01/19/2015] [Accepted: 05/18/2015] [Indexed: 11/21/2022] Open
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Kim JI, Park JM, Park SY, Choi CH, Wu HG, Ye SJ. Assessment of potential jaw-tracking advantage using control point sequences of VMAT planning. J Appl Clin Med Phys 2014; 15:4625. [PMID: 24710450 PMCID: PMC5875480 DOI: 10.1120/jacmp.v15i2.4625] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2013] [Revised: 01/02/2014] [Accepted: 11/25/2013] [Indexed: 11/23/2022] Open
Abstract
This study aims to evaluate the potential jaw-tracking advantage using control point sequences of volume volumetric modulated arc therapy (VMAT) planning. VMAT plans for patients with prostate and head and neck (H&N) cancers were converted into new static arc (SA) plans. The SA plan consisted of a series of static fields at each control point of the VMAT plan. All other machine parameters of the SA plan were perfectly identical to those of the original VMAT plan. The jaw-tracking static arc (JTSA) plans were generated with fields that closed the jaws of each SA field into the multileaf collimators (MLCs) aperture. The dosimetric advantages of JTSA over SA were evaluated in terms of a dose-volume histogram (DVH) of organ at risk (OAR) after renormalizing both plans to make the same target coverage. Both plans were delivered to the MatriXX-based COMPASS system for 3D volume dose verification. The average jaw size reduction of the JTSA along the X direction was 3.1 ± 0.9 cm for prostate patients and 6.9 ± 1.9 cm for H&N patients. For prostate patients, the organs far from the target showed larger sparing (3.7%-8.1% on average) in JTSA than the organs adjacent to the target (1.1%-1.5%). For the H&N plans, the mean dose reductions for all organs ranged from 4.3% to 11.9%. The dose reductions were more significant in the dose regions of D80, D90, and D95 than the dose regions of D5, D10, and D20 for all patients. Likewise, the deliverability and reproducibility of jaw-tracking plan were validated. The measured dosimetric advantage of JTSA over SA coincided with the calculated one above.
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Mancosu P, Navarria P, Castagna L, Reggiori G, Sarina B, Tomatis S, Alongi F, Nicolini G, Fogliata A, Cozzi L, Scorsetti M. Interplay effects between dose distribution quality and positioning accuracy in total marrow irradiation with volumetric modulated arc therapy. Med Phys 2013; 40:111713. [DOI: 10.1118/1.4823767] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Broggi S, Cantone MC, Chiara A, Di Muzio N, Longobardi B, Mangili P, Veronese I. Application of failure mode and effects analysis (FMEA) to pretreatment phases in tomotherapy. J Appl Clin Med Phys 2013; 14:265-77. [PMID: 24036868 PMCID: PMC5714567 DOI: 10.1120/jacmp.v14i5.4329] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 04/04/2013] [Accepted: 03/19/2013] [Indexed: 11/23/2022] Open
Abstract
The aim of this paper was the application of the failure mode and effects analysis (FMEA) approach to assess the risks for patients undergoing radiotherapy treatments performed by means of a helical tomotherapy unit. FMEA was applied to the preplanning imaging, volume determination, and treatment planning stages of the tomotherapy process and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system; and 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. A total of 74 failure modes were identified: 38 in the stage of preplanning imaging and volume determination, and 36 in the stage of planning. The threshold of 125 for RPN was exceeded in four cases: one case only in the phase of preplanning imaging and volume determination, and three cases in the stage of planning. The most critical failures appeared related to (i) the wrong or missing definition and contouring of the overlapping regions, (ii) the wrong assignment of the overlap priority to each anatomical structure, (iii) the wrong choice of the computed tomography calibration curve for dose calculation, and (iv) the wrong (or not performed) choice of the number of fractions in the planning station. On the basis of these findings, in addition to the safety strategies already adopted in the clinical practice, novel solutions have been proposed for mitigating the risk of these failures and to increase patient safety.
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Cantone MC, Ciocca M, Dionisi F, Fossati P, Lorentini S, Krengli M, Molinelli S, Orecchia R, Schwarz M, Veronese I, Vitolo V. Application of failure mode and effects analysis to treatment planning in scanned proton beam radiotherapy. Radiat Oncol 2013; 8:127. [PMID: 23705626 PMCID: PMC3679803 DOI: 10.1186/1748-717x-8-127] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 05/19/2013] [Indexed: 11/21/2022] Open
Abstract
Background A multidisciplinary and multi-institutional working group applied the Failure Mode and Effects Analysis (FMEA) approach to the actively scanned proton beam radiotherapy process implemented at CNAO (Centro Nazionale di Adroterapia Oncologica), aiming at preventing accidental exposures to the patient. Methods FMEA was applied to the treatment planning stage and consisted of three steps: i) identification of the involved sub-processes; ii) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system, iii) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. Results Thirty-four sub-processes were identified, twenty-two of them were judged to be potentially prone to one or more failure modes. A total of forty-four failure modes were recognized, 52% of them characterized by an RPN score equal to 80 or higher. The threshold of 125 for RPN was exceeded in five cases only. The most critical sub-process appeared related to the delineation and correction of artefacts in planning CT data. Failures associated to that sub-process were inaccurate delineation of the artefacts and incorrect proton stopping power assignment to body regions. Other significant failure modes consisted of an outdated representation of the patient anatomy, an improper selection of beam direction and of the physical beam model or dose calculation grid. The main effects of these failures were represented by wrong dose distribution (i.e. deviating from the planned one) delivered to the patient. Additional strategies for risk mitigation, easily and immediately applicable, consisted of a systematic information collection about any known implanted prosthesis directly from each patient and enforcing a short interval time between CT scan and treatment start. Moreover, (i) the investigation of dedicated CT image reconstruction algorithms, (ii) further evaluation of treatment plan robustness and (iii) implementation of independent methods for dose calculation (such as Monte Carlo simulations) may represent novel solutions to increase patient safety. Conclusions FMEA is a useful tool for prospective evaluation of patient safety in proton beam radiotherapy. The application of this method to the treatment planning stage lead to identify strategies for risk mitigation in addition to the safety measures already adopted in clinical practice.
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Affiliation(s)
- Marie Claire Cantone
- Dipartimento di Fisica, Università degli Studi di Milano, Via Celoria 16, 20133, Milano, Italy
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Lee YK, Bedford JL, McNair HA, Hawkins MA. Comparison of deliverable IMRT and VMAT for spine metastases using a simultaneous integrated boost. Br J Radiol 2013; 86:20120466. [PMID: 23385999 DOI: 10.1259/bjr.20120466] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To effectively treat spine metastases, significant dose must be delivered to regions surrounding the spinal cord. We present a study comparing both step-and-shoot intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) techniques to deliver a concomitant hypofractionated prescription dose to the diseased region and to the involved vertebrae. METHODS Seven-field IMRT and a single arc VMAT were inversely planned on five (two cervical and three thoracic) spinal metastatic patients. Planning target volumes PTVm (macroscopic) and PTVe (elective involved vertebrae) and associated organs at risk were localised. Mean doses of 35 Gy to PTVm and 20 Gy to PTVe were prescribed in five fractions. Dose statistics, estimated delivery time and results of verification using Delta(4) (ScandiDos, Uppsala, Sweden) were compared. RESULTS Deliverable plans were achieved with both IMRT and VMAT. The coverage to PTV was similar for both IMRT and VMAT (p=0.5) and the dose to the regions adjacent to the spinal cord was 1% higher with VMAT (p=0.04). The mean delivery time for VMAT was 3.5 min compared with 10.5 min for IMRT. Fewer monitor units were required to deliver IMRT than to deliver VMAT. The median (range) percentage of measured points with a γ-index <1 with 3%/3 mm was 100 (99.9-100)% for IMRT and 100 (88.5-100)% for VMAT. CONCLUSION Both VMAT and IMRT can deliver the concomitant hypofractionated regime proposed, and both offer different benefits in dose delivery. IMRT is currently preferred for its superior pre-treatment verification results and shorter planning times. ADVANCES IN KNOWLEDGE This study explores the feasibility of delivering tumouricidal doses of radiation to metastatic spine disease in the vicinity of the spinal cord.
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Affiliation(s)
- Y K Lee
- Joint Department of Physics, The Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Sutton, UK.
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Mancosu P, Castiglioni S, Reggiori G, Catalano M, Alongi F, Pellegrini C, Arcangeli S, Tozzi A, Lobefalo F, Fogliata A, Navarria P, Cozzi L, Scorsetti M. Stereotactic body radiation therapy for liver tumours using flattening filter free beam: dosimetric and technical considerations. Radiat Oncol 2012; 7:16. [PMID: 22296849 PMCID: PMC3292972 DOI: 10.1186/1748-717x-7-16] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 02/01/2012] [Indexed: 12/25/2022] Open
Abstract
Purpose To report the initial institute experience in terms of dosimetric and technical aspects in stereotactic body radiation therapy (SBRT) delivered using flattening filter free (FFF) beam in patients with liver lesions. Methods and Materials From October 2010 to September 2011, 55 consecutive patients with 73 primary or metastatic hepatic lesions were treated with SBRT on TrueBeam using FFF beam and RapidArc technique. Clinical target volume (CTV) was defined on multi-phase CT scans, PET/CT, MRI, and 4D-CT. Dose prescription was 75 Gy in 3 fractions to planning target volume (PTV). Constraints for organs at risk were: 700 cc of liver free from the 15 Gy isodose, Dmax < 21 Gy for stomach and duodenum, Dmax < 30 Gy for heart, D0.1 cc < 18 Gy for spinal cord, V15 Gy < 35% for kidneys. The dose was downscaled in cases of not full achievement of dose constraints. Daily cone beam CT (CBCT) was performed. Results Forty-three patients with a single lesion, nine with two lesions and three with three lesions were treated with this protocol. Target and organs at risk objectives were met for all patients. Mean delivery time was 2.8 ± 1.0 min. Pre-treatment plan verification resulted in a Gamma Agreement Index of 98.6 ± 0.8%. Mean on-line co-registration shift of the daily CBCT to the simulation CT were: -0.08, 0.05 and -0.02 cm with standard deviations of 0.33, 0.39 and 0.55 cm in, vertical, longitudinal and lateral directions respectively. Conclusions SBRT for liver targets delivered by means of FFF resulted to be feasible with short beam on time.
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Affiliation(s)
- Pietro Mancosu
- IRCCS Istituto Clinico Humanitas, Rozzano (Milano), Italy.
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Mancosu P, Navarria P, Castagna L, Roggio A, Pellegrini C, Reggiori G, Fogliata A, Lobefalo F, Castiglioni S, Alongi F, Cozzi L, Santoro A, Scorsetti M. Anatomy driven optimization strategy for total marrow irradiation with a volumetric modulated arc therapy technique. J Appl Clin Med Phys 2012; 13:3653. [PMID: 22231216 PMCID: PMC5716136 DOI: 10.1120/jacmp.v13i1.3653] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 09/05/2011] [Accepted: 09/03/2011] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to evaluate the possibility of dose distribution optimization for total marrow irradiation (TMI) employing volumetric‐modulated arc therapy (VMAT) with RapidArc (RA) technology setting isocenter's positions and jaw's apertures according to patient's anatomical features. Plans for five patients were generated with the RA engine (PROIII): eight arcs were distributed along four isocenters and simultaneously optimized with collimator set to 90°. Two models were investigated for geometrical settings of arcs: (1) in the “symmetric” model, isocenters were equispaced and field apertures were set the same for all arcs to uniformly cover the entire target length; (2) in the “anatomy driven” model, both field sizes and isocenter positions were optimized in order to minimize the target volume near the field edges (i.e., to maximize the freedom of motion of MLC leaves inside the field aperture (for example, avoiding arcs with ribs and iliac wings in the same BEV)). All body bones from the cranium to mid of the femurs were defined as PTV; the maximum length achieved in this study was 130 cm. Twelve (12) Gy in 2 Gy/fractions were prescribed in order to obtain the covering of 85% of the PTV by 100% of the prescribed dose. For all organs at risk (including brain, optical structures, oral and neck structures, lungs, heart, liver, kidneys, spleen, bowels, bladder, rectum, genitals), planning strategy aimed to maximize sparing according to ALARA principles, looking to reach a mean dose lower than 6 Gy (i.e., 50% of the prescribed dose). Mean MU/fraction resulted 3184±354 and 2939±264 for the two strategies, corresponding to a reduction of 7% (range −2% to 13%) for (1) and (2). Target homogeneity, defined as D2%−D98% was 18% better for (2). Mean dose to the healthy tissue, defined as body minus PTV, had 10% better reduction with (2). The isocenter's position and the jaw's apertures are significant parameters in the optimization of the TMI with RA technique, giving the medical physicist a crucial role in driving the optimization and thus obtaining the best plan. A clinical protocol started in our department in October 2010. PACS numbers: 87.55.de, 87.55.dk, 87.56.nk, 87.57.uq
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Affiliation(s)
- Pietro Mancosu
- Radiation Oncology Dept., Humanitas Cancer Center, Milano (Rozzano), Italy.
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Bedford JL, Convery HM, Hansen VN, Saran FH. Paraspinal volumetric modulated arc therapy. Br J Radiol 2012; 85:1128-33. [PMID: 22215885 DOI: 10.1259/bjr/83207140] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The processes involved in the treatment of paraspinal tumours by volumetric modulated arc therapy (VMAT) are described here by means of an illustrative case. METHODS Az single anticlockwise arc from gantry angle 179° to 181° was constructed using SmartArc (Philips Radiation Oncology Systems, Fitchburg, WI) with control points spaced at 2°. The dose prescription was 60 Gy in 30 fractions to cover the planning target volume (PTV) as uniformly as possible while sparing the 0.3-cm planning risk volume (PRV) around the spinal cord. The plan was verified before treatment using a diode array phantom and radiochromic film. Treatment delivery was on a Synergy linear accelerator with a beam modulator head (Elekta Ltd, Crawley, UK). RESULTS Homogeneous dose coverage of the PTV was achieved with a D(2%) of 62.0 Gy and D(98%) of 55.6 Gy. Maximum spinal cord dose was 49.9 Gy to 0.1 cm(3) and maximum dose to the spinal cord PRV was 55.4 Gy to 0.1 cm(3). At pre-treatment verification, the percentage of the high-dose region receiving a dose within 3% and 3 mm of the planned dose was 98.8% with the diode array and 93.4% with film. Delivery time was 2 min 15 s and the course of treatment was successfully completed. CONCLUSIONS VMAT was successfully planned, verified and delivered for this challenging tumour site. VMAT provides a very suitable method of treating complex paraspinal tumours, offering a high-quality conformal dose distribution with a short delivery time.
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Affiliation(s)
- J L Bedford
- The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, Sutton, UK.
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