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Pan L, Du B, Zhu Z, Meng Q, Zhong R, Wang S. A comparative study of volumetric modulated arc therapy plans based on the equivalent uniform dose optimization for left-sided breast cancer. Radiat Phys Chem Oxf Engl 1993 2023. [DOI: 10.1016/j.radphyschem.2023.110945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
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Wang S, Zhou L, Xue J, Lan J, Deng L, Yi T, Lu Y. Comparison of biologically effective dose for treatment planning in the fixed-beam intensity-modulated radiotherapy and the volumetric-modulated arc therapy for the typical types of cancer. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2018.12.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Li T, Scheuermann R, Lin A, Teo BKK, Zou W, Swisher-McClure S, Alonso-Basanta M, Lukens JN, Fotouhi Ghiam A, Kennedy C, Kim MM, Mihailidis D, Metz JM, Dong L. Impact of Multi-leaf Collimator Parameters on Head and Neck Plan Quality and Delivery: A Comparison between Halcyon™ and Truebeam® Treatment Delivery Systems. Cureus 2018; 10:e3648. [PMID: 30723647 PMCID: PMC6351111 DOI: 10.7759/cureus.3648] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Purpose A new dual-layer multi-leaf collimator (MLC) system with several improved characteristics was introduced with the Varian Halcyon™ treatment platform. This study evaluated this new MLC's impact on head and neck plan quality and delivery efficiency. Methods Nine patients were retrospectively studied with Institutional Review Board (IRB) approval. To compare plan quality between the Halcyon dual-layer MLC and Truebeam® MLC, all patients were replanned with the same prescription and target coverage following the institutional clinical protocol for both platforms and using both intensity modulated radiation therapy (IMRT) or volumetrically modulated arc therapy (VMAT) techniques. Organs-at-risk (OAR) dose-volume histogram (DVH) statistics were compared along with total plan monitor units (MU). To evaluate delivery efficiency, actual beam-on time for five patients' plans were recorded and compared. To evaluate the impact of MLC performance parameters on plan quality, virtual MLC models were generated by matching Truebeam MLC's parameters to those of the Halcyon dual-layer MLC both individually and combined. OAR doses were then compared between these virtual MLCs, the Truebeam MLC, and the actual Halcyon MLC. Results Overall the Halcyon dual-layer MLC provided similar plan quality compared to Truebeam MLC for VMAT plans, and improved sparing for majority of the OARs when using IMRT. Paired comparison showed median dose differences in mean doses to the parotids, cochlea, esophagus, and larynx ranged from -0.83 Gy to 0.37 Gy for VMAT, and from -4.79 Gy to -0.04 Gy for IMRT, with negative values indicating improved performance by Halcyon. Despite a slight increase in plan MU, the Halcyon reduced the total beam-on time by 42.8 ± 8.5%. Virtual MLC simulations demonstrated that matching MLC transmission accounted for nearly half of the total dose difference between Halcyon and Truebeam IMRT plans. Conclusion When compared to the Truebeam, the Halcyon's dual-layer MLC achieved similar plan quality using VMAT, and improved OAR sparing using IMRT, while providing nearly twice as fast treatment delivery. Reduction in MLC transmission is the dominating factor contributing to dosimetric differences in OAR sparing.
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Affiliation(s)
- Taoran Li
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Ryan Scheuermann
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Alexander Lin
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Boon-Keng Kevin Teo
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Wei Zou
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Samuel Swisher-McClure
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Michelle Alonso-Basanta
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - John N Lukens
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Alireza Fotouhi Ghiam
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Chris Kennedy
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Michele M Kim
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Dimitris Mihailidis
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - James M Metz
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
| | - Lei Dong
- Department of Radiation Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, USA
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Zhu XR, Poenisch F, Li H, Zhang X, Sahoo N, Wu RY, Li X, Lee AK, Chang EL, Choi S, Pugh T, Frank SJ, Gillin MT, Mahajan A, Grosshans DR. A single-field integrated boost treatment planning technique for spot scanning proton therapy. Radiat Oncol 2014; 9:202. [PMID: 25212571 PMCID: PMC4262206 DOI: 10.1186/1748-717x-9-202] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Accepted: 09/05/2014] [Indexed: 01/25/2023] Open
Abstract
Purpose Intensity modulated proton therapy (IMPT) plans are normally generated utilizing multiple field optimization (MFO) techniques. Similar to photon based IMRT, MFO allows for the utilization of a simultaneous integrated boost in which multiple target volumes are treated to discrete doses simultaneously, potentially improving plan quality and streamlining quality assurance and treatment delivery. However, MFO may render plans more sensitive to the physical uncertainties inherent to particle therapy. Here we present clinical examples of a single-field integrated boost (SFIB) technique for spot scanning proton therapy based on single field optimization (SFO) treatment-planning techniques. Methods and materials We designed plans of each type for illustrative patients with central nervous system (brain and spine), prostate and head and neck malignancies. SFIB and IMPT plans were constructed to deliver multiple prescription dose levels to multiple targets using SFO or MFO, respectively. Dose and fractionation schemes were based on the current clinical practice using X-ray IMRT in our clinic. For inverse planning, dose constraints were employed to achieve the desired target coverage and normal tissue sparing. Conformality and inhomogeneity indices were calculated to quantify plan quality. We also compared the worst-case robustness of the SFIB, sequential boost SFUD, and IMPT plans. Results The SFIB technique produced more conformal dose distributions than plans generated by sequential boost using a SFUD technique (conformality index for prescription isodose levels; 0.585 ± 0.30 vs. 0.435 ± 0.24, SFIB vs. SFUD respectively, Wilcoxon matched-pair signed rank test, p < 0.01). There was no difference in the conformality index between SFIB and IMPT plans (0.638 ± 0.27 vs. 0.633 ± 0.26, SFIB vs. IMPT, respectively). Heterogeneity between techniques was not significantly different. With respect to clinical metrics, SFIB plans proved more robust than the corresponding IMPT plans. Conclusions SFIB technique for scanning beam proton therapy (SSPT) is now routinely employed in our clinic. The SFIB technique is a natural application of SFO and offers several advantages over SFUD, including more conformal plans, seamless treatment delivery and more efficient planning and QA. SFIB may be more robust than IMPT and has been the treatment planning technique of choice for some patients.
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Affiliation(s)
- Xiaorong Ronald Zhu
- Departments of Radiation Physics, The University of Texas MD Anderson Cancer Center, Unit 1150, 1515 Holcombe Boulevard, Houston, TX, USA.
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Wilkie JR, Matuszak MM, Feng M, Moran JM, Fraass BA. Use of plan quality degradation to evaluate tradeoffs in delivery efficiency and clinical plan metrics arising from IMRT optimizer and sequencer compromises. Med Phys 2014; 40:071708. [PMID: 23822412 DOI: 10.1118/1.4808118] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Plan degradation resulting from compromises made to enhance delivery efficiency is an important consideration for intensity modulated radiation therapy (IMRT) treatment plans. IMRT optimization and/or multileaf collimator (MLC) sequencing schemes can be modified to generate more efficient treatment delivery, but the effect those modifications have on plan quality is often difficult to quantify. In this work, the authors present a method for quantitative assessment of overall plan quality degradation due to tradeoffs between delivery efficiency and treatment plan quality, illustrated using comparisons between plans developed allowing different numbers of intensity levels in IMRT optimization and/or MLC sequencing for static segmental MLC IMRT plans. METHODS A plan quality degradation method to evaluate delivery efficiency and plan quality tradeoffs was developed and used to assess planning for 14 prostate and 12 head and neck patients treated with static IMRT. Plan quality was evaluated using a physician's predetermined "quality degradation" factors for relevant clinical plan metrics associated with the plan optimization strategy. Delivery efficiency and plan quality were assessed for a range of optimization and sequencing limitations. The "optimal" (baseline) plan for each case was derived using a clinical cost function with an unlimited number of intensity levels. These plans were sequenced with a clinical MLC leaf sequencer which uses >100 segments, assuring delivered intensities to be within 1% of the optimized intensity pattern. Each patient's optimal plan was also sequenced limiting the number of intensity levels (20, 10, and 5), and then separately optimized with these same numbers of intensity levels. Delivery time was measured for all plans, and direct evaluation of the tradeoffs between delivery time and plan degradation was performed. RESULTS When considering tradeoffs, the optimal number of intensity levels depends on the treatment site and on the stage in the process at which the levels are limited. The cost of improved delivery efficiency, in terms of plan quality degradation, increased as the number of intensity levels in the sequencer or optimizer decreased. The degradation was more substantial for the head and neck cases relative to the prostate cases, particularly when fewer than 20 intensity levels were used. Plan quality degradation was less severe when the number of intensity levels was limited in the optimizer rather than the sequencer. CONCLUSIONS Analysis of plan quality degradation allows for a quantitative assessment of the compromises in clinical plan quality as delivery efficiency is improved, in order to determine the optimal delivery settings. The technique is based on physician-determined quality degradation factors and can be extended to other clinical situations where investigation of various tradeoffs is warranted.
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Affiliation(s)
- Joel R Wilkie
- Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 48109, USA
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Wang S, Ai P, Xie L, Xu Q, Bai S, Lu Y, Li P, Chen N. Dosimetric comparison of different multileaf collimator leaves in treatment planning of intensity-modulated radiotherapy for cervical cancer. Med Dosim 2013; 38:454-9. [PMID: 24099965 DOI: 10.1016/j.meddos.2013.08.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2012] [Revised: 06/28/2013] [Accepted: 08/14/2013] [Indexed: 02/05/2023]
Abstract
To study the effect of multileaf collimator (MLC) leaf widths (standard MLC [sMLC] width of 10mm and micro-MLC [mMLC] width of 4mm) on intensity-modulated radiotherapy (IMRT) for cervical cancer. Between January 2010 and August 2010, a retrospective analysis was conducted on 12 patients with cervical cancer. The treatment plans for all patients were generated with the same machine setup parameters and optimization methods in a treatment planning system (TPS) based on 2 commercial Elekta MLC devices. The dose distribution for the planning tumor volume (PTV), the dose sparing for organs at risk (OARs), the monitor units (MUs), and the number of IMRT segments were evaluated. For the delivery efficiency, the MUs were significantly higher in the sMLC-IMRT plan than in the mMLC-IMRT plan (802 ± 56.9 vs 702 ± 56.7; p < 0.05). The number of segments in the plans were 58.75 ± 1.8 and 59 ± 1.04 (p > 0.05). For the planning quality, the conformity index (CI) between the 2 paired IMRT plans with the mMLC and the sMLC did not differ significantly (average: 0.817 ± 0.024 vs 0.810 ± 0.028; p > 0.05). The differences of the homogeneity index (HI) between the 2 paired plans were statistically significant (average: 1.122 ± 0.010 vs 1.132 ± 0.014; p < 0.01). For OARs, the rectum, bladder, small intestine, and bony pelvis were evaluated in terms of V10, V20, V30, and V40, percentage of contoured OAR volumes receiving 10, 20, 30, and 40Gy, respectively, and the mean dose (Dmean) received. The IMRT plans with the mMLC protected the OARs better than the plans with the sMLC. There were significant differences (p < 0.05) in evaluated parameters between the 2 paired IMRT plans, except for V30 and V40 of the rectum and V10, V20, V40, and Dmean of the bladder. IMRT plans with the mMLC showed advantages over the plans with the sMLC in dose homogeneity for targets, dose sparing of OARs, and fewer MUs in cervical cancer.
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Affiliation(s)
- Shichao Wang
- Radiation and Physics Center, Cancer Center, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China; State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
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Hopkins DN, Maqbool M, Islam MS. Linear attenuation coefficient and buildup factor of MCP-96 alloy for dose accuracy, beam collimation, and radiation protection. Radiol Phys Technol 2012; 5:229-36. [PMID: 22585280 DOI: 10.1007/s12194-012-0158-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 04/25/2012] [Accepted: 04/29/2012] [Indexed: 11/29/2022]
Abstract
The linear attenuation coefficients and buildup factor of MCP-96 alloy were determined for (60)Co, (54)Mn, and (137)Cs gamma emitters and a NaI detector. The thickness of the MCP-96 attenuator was varied from 1 to 4 cm. A collimated beam of gamma rays was allowed to pass through various thicknesses of the MCP-96 alloy. The attenuated beam was detected by a NaI detector, and data were recorded by a multichannel analyzer. The run was repeated without the collimator for broad-beam geometry. For each run, the attenuated beam intensity was normalized by the intensity of the unattenuated incident beam obtained by removing the attenuators. Linear attenuation coefficients were determined by plotting of the intensity of the collimated beam against the attenuator thickness. For every thickness of the alloy, the ratio of the attenuated to the unattenuated beam was found to be higher in broad-beam geometry as compared to the same ratio in narrow-beam geometry. We used the difference in these ratios in broad and narrow-beam geometries to calculate the buildup factor. The buildup factor was found to increase with beam energy and attenuator thickness. Variation in the source-to-detector distance gave a lower value of the buildup factor for a small and a large distance and a higher value for an intermediate distance. The buildup factor was found to be greater than 1 in all cases. We conclude that the buildup factor must be calculated and incorporated for dose correction and precision when the MCP-96 alloy is used for tissue compensation or radiation shielding and protection purposes.
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Affiliation(s)
- Deidre N Hopkins
- Department of Physics and Astronomy, Ball State University, Muncie, IN 47306, USA
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Intensity-modulated radiotherapy after extrapleural pneumonectomy in the combined-modality treatment of malignant pleural mesothelioma. J Thorac Oncol 2011; 6:1132-41. [PMID: 21532502 DOI: 10.1097/jto.0b013e3182199819] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Local therapy is becoming increasingly important as a part of the definitive treatment for malignant pleural mesothelioma after extrapleural pneumonectomy (EPP) because of the emergence of trimodality therapy consisted of chemotherapy, EPP, and adjuvant radiotherapy. Herein, we explore the current evidence and indications for adjuvant intensity-modulated radiotherapy (IMRT), as well as how to further improve this technique and adapt new technology in the delivering adjuvant radiotherapy in the setting of trimodality therapy. METHODS A systematic review of relevant studies identified through PubMed, ISI Web of Knowledge (Web of Science), the Cochrane Library, and the National Guideline Clearinghouse search engines was performed. RESULTS Local control remains poor despite the inclusion of conventional adjuvant radiation therapy in trimodality therapy. This can be improved by the delivery of adjuvant IMRT. However, IMRT can be associated with severe pulmonary toxicity if the radiation dose to the remaining lung is not kept to a very low level. This is especially true when patients are receiving chemotherapy. New advances in technology can allow for lower doses to the contralateral lung, decreased treatment delivery time, and improved target dose coverage. CONCLUSION Excellent local control can be achieved through adjuvant IMRT after EPP for malignant pleural mesothelioma. Severe pulmonary toxicity may be avoided by setting stringent dose constraints for the contralateral lung. This can be aided by the advances in technology. Post-treatment surveillance may be reliably conducted by periodical [18F]-fluorodeoxyglucose-positron emission tomography imaging.
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Zhang X, Li X, Quan EM, Pan X, Li Y. A methodology for automatic intensity-modulated radiation treatment planning for lung cancer. Phys Med Biol 2011; 56:3873-93. [PMID: 21654043 DOI: 10.1088/0031-9155/56/13/009] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In intensity-modulated radiotherapy (IMRT), the quality of the treatment plan, which is highly dependent upon the treatment planner's level of experience, greatly affects the potential benefits of the radiotherapy (RT). Furthermore, the planning process is complicated and requires a great deal of iteration, and is often the most time-consuming aspect of the RT process. In this paper, we describe a methodology to automate the IMRT planning process in lung cancer cases, the goal being to improve the quality and consistency of treatment planning. This methodology (1) automatically sets beam angles based on a beam angle automation algorithm, (2) judiciously designs the planning structures, which were shown to be effective for all the lung cancer cases we studied, and (3) automatically adjusts the objectives of the objective function based on a parameter automation algorithm. We compared treatment plans created in this system (mdaccAutoPlan) based on the overall methodology with plans from a clinical trial of IMRT for lung cancer run at our institution. The 'autoplans' were consistently better, or no worse, than the plans produced by experienced medical dosimetrists in terms of tumor coverage and normal tissue sparing. We conclude that the mdaccAutoPlan system can potentially improve the quality and consistency of treatment planning for lung cancer.
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Affiliation(s)
- Xiaodong Zhang
- Department of Radiation Physics, Unit 94, MD Anderson Cancer Center, The University of Texas, 1515 Holcombe Blvd, Houston, TX 77030, USA.
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Intensity modulated radiosurgery for the spine: Dosimetric impact of beamlet size variation in the leaf travel direction. Radiother Oncol 2011; 98:227-33. [DOI: 10.1016/j.radonc.2010.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 09/07/2010] [Accepted: 10/03/2010] [Indexed: 01/09/2023]
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Gong Y, Wang S, Zhou L, Liu Y, Xu Y, Lu Y, Bai S, Fu Y, Xu Q, Jiang Q. Dosimetric comparison using different multileaf collimeters in intensity-modulated radiotherapy for upper thoracic esophageal cancer. Radiat Oncol 2010; 5:65. [PMID: 20633283 PMCID: PMC2912923 DOI: 10.1186/1748-717x-5-65] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Accepted: 07/15/2010] [Indexed: 02/05/2023] Open
Abstract
Purpose To study the impacts of multileaf collimators (MLC) width [standard MLC width of 10 mm (sMLC) and micro-MLC width of 4 mm (mMLC)] in the intensity-modulated radiotherapy (IMRT) planning for the upper thoracic esophageal cancer (UTEC). Methods and materials 10 patients with UTEC were retrospectively planned with the sMLC and the mMLC. The monitor unites (MUs) and dose volume histogram-based parameters [conformity index (CI) and homogeneous index (HI)] were compared between the IMRT plans with sMLC and with mMLC. Results The IMRT plans with the mMLC were more efficient (average MUs: 703.1 ± 68.3) than plans with the sMLC (average MUs: 833.4 ± 73.8) (p < 0.05). Also, compared to plans with the sMLC, the plans with the mMLC showed advantages in dose coverage of the planning gross tumor volume (Pgtv) (CI 0.706 ± 0.056/HI 1.093 ± 0.021) and the planning target volume (PTV) (CI 0.707 ± 0.029/HI 1.315 ± 0.013) (p < 0.05). In addition, the significant dose sparing in the D5 (3260.3 ± 374.0 vs 3404.5 ± 374.4)/gEUD (1815.1 ± 281.7 vs 1849.2 ± 297.6) of the spinal cord, the V10 (33.2 ± 6.5 vs 34.0 ± 6.7), V20 (16.0 ± 4.6 vs 16.6 ± 4.7), MLD (866.2 ± 174.1 vs 887.9 ± 172.1) and gEUD (938.6 ± 175.2 vs 956.8 ± 171.0) of the lungs were observed in the plans with the mMLC, respectively (p < 0.05). Conclusions Comparing to the sMLC, the mMLC not only demonstrated higher efficiencies and more optimal target coverage, but also considerably improved the dose sparing of OARs in the IMRT planning for UTEC.
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Affiliation(s)
- Youling Gong
- Department of Thoracic Oncology, Cancer Center, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China
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Wang S, Gong Y, Xu Q, Bai S, Lu Y, Jiang Q, Chen N. Impacts of multileaf collimators leaf width on intensity-modulated radiotherapy planning for nasopharyngeal carcinoma: analysis of two commercial elekta devices. Med Dosim 2010; 36:153-9. [PMID: 20488691 DOI: 10.1016/j.meddos.2010.02.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 01/12/2010] [Accepted: 02/18/2010] [Indexed: 02/05/2023]
Abstract
We compared the impacts of multileaf collimator (MLC) widths (standard MLC width of 10 mm [SMLC] and micro-MLC width of 4 mm [MMLC]) on intensity-modulated radiotherapy (IMRT) planning for nasopharyngeal carcinoma (NPC). Ten patients with NPC were recruited in this study. In each patient's case, plans were generated with the same machine setup parameter and optimizing methods in a treatment planning system according to 2 commercial Elekta MLC devices. All of the parameters were collected from dose-volume histograms of paired plans and evaluated. The average conformity index (CI) and homogeneous index (HI) for the planning gross target volume in IMRT plans with MMLC were 0.790 ± 0.036 and 1.062 ± 0.011, respectively. Data in plans with SMLC were 0.754 ± 0.038 and 1.070 ± 0.010, respectively. The differences were statistically significant (p < 0.05). Compared with CI and HI for planning target volume in paired plans, data with MMLC obviously were better than those with SMLC (CI: 0.858 ± 0.026 vs. 0.850 ± 0.021, p < 0.05; and HI: 1.185 ± 0.011 vs. 1.195 ± 0.011, p < 0.05). However, there was no statistical significance between evaluated parameters (Dmean, Dmax, D₅, gEUD, or NTCP) for organs at risk (OARs) in the 2 paired IMRT plans. According to these two kinds of Elekta MLC devices, IMRT plans with the MMLC have significant advantages in dose coverage for the targets, with more efficiency in treatment for NPC but fail to improve dose sparing of the OARs.
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Affiliation(s)
- Shichao Wang
- Radiation and Physics Center, West China Hospital, Sichuan University, Chengdu, Sichuan Province, PR China
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Radiotherapy in Malignant Pleural Mesothelioma. Int J Radiat Oncol Biol Phys 2009; 75:326-37. [PMID: 19735859 DOI: 10.1016/j.ijrobp.2009.06.037] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Revised: 06/03/2009] [Accepted: 06/04/2009] [Indexed: 11/21/2022]
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Jang SY, Liu HH, Mohan R. Underestimation of Low-Dose Radiation in Treatment Planning of Intensity-Modulated Radiotherapy. Int J Radiat Oncol Biol Phys 2008; 71:1537-46. [PMID: 18513883 DOI: 10.1016/j.ijrobp.2008.04.014] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2007] [Revised: 03/26/2008] [Accepted: 04/07/2008] [Indexed: 11/18/2022]
Affiliation(s)
- Si Young Jang
- Department of Radiation Physics, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA
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Sterzing F, Sroka-Perez G, Schubert K, Münter MW, Thieke C, Huber P, Debus J, Herfarth KK. Evaluating target coverage and normal tissue sparing in the adjuvant radiotherapy of malignant pleural mesothelioma: helical tomotherapy compared with step-and-shoot IMRT. Radiother Oncol 2008; 86:251-7. [PMID: 18207597 DOI: 10.1016/j.radonc.2007.12.010] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2007] [Revised: 12/08/2007] [Accepted: 12/11/2007] [Indexed: 02/08/2023]
Abstract
PURPOSE To evaluate the potential of helical tomotherapy in the adjuvant treatment of malignant pleural mesothelioma and compare target homogeneity, conformity and normal tissue dose with step-and-shoot intensity-modulated radiotherapy. METHODS AND MATERIALS Ten patients with malignant pleural mesothelioma who had undergone neoadjuvant chemotherapy with cisplatin and permetrexed followed by extrapleural pneumonectomy (EPP) were treated in our department with 54 Gy to the hemithorax delivered by step-and-shoot IMRT. A planning comparison was performed by creating radiation plans for helical tomotherapy. The different plans were compared by analysing target homogeneity using the homogeneity indices HI(max) and HI(min) and target conformity by using the conformity index CI(95). To assess target coverage and normal tissue sparing TV(90), TV(95) and mean and maximum doses were compared. RESULTS Both modalities achieved excellent dose distributions while sparing organs at risk. Target coverage and homogeneity could be increased significantly with helical tomotherapy compared with step-and-shoot IMRT. Mean dose to the contralateral lung could be lowered beyond 5 Gy. CONCLUSIONS Our planning study showed that helical tomotherapy is an excellent option for the adjuvant intensity-modulated radiotherapy of MPM. It is capable of improving target coverage and homogeneity.
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Affiliation(s)
- Florian Sterzing
- Department of Radiation Oncology, University of Heidelberg, Germany.
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Invasive Thymoma: Postoperative Mediastinal Irradiation, and Low-Dose Entire Hemithorax Irradiation in Patients with Pleural Dissemination. J Thorac Oncol 2008; 3:75-81. [DOI: 10.1097/jto.0b013e31815e8b73] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Achterberg N, Müller RG. Multibeam tomotherapy: a new treatment unit devised for multileaf collimation, intensity-modulated radiation therapy. Med Phys 2007; 34:3926-42. [PMID: 17985638 DOI: 10.1118/1.2779129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A fully integrated system for treatment planning, application, and verification for automated multileaf collimator (MLC) based, intensity-modulated, image-guided, and adaptive radiation therapy (IMRT, IGRT and ART, respectively) is proposed. Patient comfort, which was the major development goal, will be achieved through a new unit design and short treatment times. Our device for photon beam therapy will consist of a new dual energy linac with five fixed treatment heads positioned evenly along one plane but one electron beam generator only. A minimum of moving parts increases technical reliability and reduces motion times to a minimum. Motion is allowed solely for the MLCs, the robotic patient table, and the small angle gantry rotation of +/- 36 degrees. Besides sophisticated electron beam guidance, this compact setup can be built using existing modules. The flattening-filter-free treatment heads are characterized by reduced beam-on time and contain apertures restricted in one dimension to the area of maximum primary fluence output. In the case of longer targets, this leads to a topographic intensity modulation, thanks to the combination of "step and shoot" MLC delivery and discrete patient couch motion. Owing to the limited number of beam directions, this multislice cone beam serial tomotherapy is referred to as "multibeam tomotherapy." Every patient slice is irradiated by one treatment head at any given moment but for one subfield only. The electron beam is then guided to the next head ready for delivery, while the other heads are preparing their leaves for the next segment. The "Multifocal MLC-positioning" algorithm was programmed to enable treatment planning and optimize treatment time. We developed an overlap strategy for the longitudinally adjacent fields of every beam direction, in doing so minimizing the field match problem and the effects of possible table step errors. Clinical case studies show for the same or better planning target volume coverage, better organ-at-risk sparing, and comparable mean integral dose to the normal tissue a reduction in treatment time by more than 50% to only a few minutes in comparison to high-quality 3-D conformal and IMRT treatments. As a result, it will be possible to incorporate features for better patient positioning and image guidance, while sustaining reasonable overall treatment times at the same time. The virtual multibeam tomotherapy design study TOM'5-CT contains a dedicated electron beam CT (TOM'AGE) and an objective optical topometric patient positioning system (TOPOS). Thanks to the wide gantry bore of 120 cm and slim gantry depths of 70 cm, patients can be treated very comfortably, in all cases tumor-isocentrically, as well as with noncoplanar beam arrangements as in stereotactic radiosurgery with a couch rotation of up to +/- 54 degrees. The TOM'5 treatment unit on which this theoretical concept is based has a stand-alone depth of 40 cm and an outer diameter of 245 cm; the focus-isocenter distance of the heads is 100 cm with a field size of 40 cm x 7 cm and 0.5 cm leaves, which operate perpendicular to the axis of table motion.
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Affiliation(s)
- Nils Achterberg
- Strahlenklinik, Universitätsklinikum Erlangen, Universitätstrasse 27, 91054 Erlangen, Germany.
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Topolnjak R, van der Heide UA, Meijer GJ, van Asselen B, Raaijmakers CPJ, Lagendijk JJW. Influence of the linac design on intensity-modulated radiotherapy of head-and-neck plans. Phys Med Biol 2006; 52:169-82. [PMID: 17183134 DOI: 10.1088/0031-9155/52/1/011] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, we quantify the impact of linac/MLC design parameters on IMRT treatment plans. The investigated parameters were leaf width in the MLC, leaf transmission, related to the thickness of the leaves, and penumbra related primarily to the source size. Seven head-and-neck patients with stage T1-T3N0-N2cM0 oropharyngeal cancer were studied. For each patient nine plans were made with a different set of linac/MLC parameters. The plans were optimized in Pinnacle(3) v7.6c and PLATO RTS v2.6.4, ITP v1.1.8. A hypothetical ideal linac/MLC was introduced to investigate the influence of one parameter at a time without interaction of other parameters. When any of the three parameters was increased from the ideal set-up values (leaf width 2.5 mm, transmission 0%, penumbra 3 mm), the mean dose to the parotid glands increased, given the same tumour coverage. The largest increase was found for increasing leaf transmission. The investigation showed that by changing more than one parameter of the ideal linac/MLC set-up, the increase in the mean dose was smaller than the sum of dose increments for each parameter separately. As a reference to clinical practice, we also optimized the plans of the seven patients with the clinically used Elekta SLi 15, equipped with a standard MLC with a leaf width of 10 mm. As compared to the ideal linac, this resulted in an increase of the average dose to the parotid glands of 5.8 Gy.
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Affiliation(s)
- R Topolnjak
- Department of Radiotherapy, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
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Komaki R, Liao Z, Liu H, Tucker S, Rice D. Fatal pneumonitis associated with intensity-modulated radiation therapy for mesothelioma: In regard to Allen et al. (Int J Radiat Oncol Biol Phys 2006;65:640–645). Int J Radiat Oncol Biol Phys 2006; 66:1595-6; author reply 1596. [PMID: 17126220 DOI: 10.1016/j.ijrobp.2006.09.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Accepted: 09/01/2006] [Indexed: 10/23/2022]
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Jang SY, Liu HH, Wang X, Vassiliev ON, Siebers JV, Dong L, Mohan R. Dosimetric verification for intensity-modulated radiotherapy of thoracic cancers using experimental and Monte Carlo approaches. Int J Radiat Oncol Biol Phys 2006; 66:939-48. [PMID: 17011466 DOI: 10.1016/j.ijrobp.2006.06.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Revised: 06/21/2006] [Accepted: 06/23/2006] [Indexed: 11/23/2022]
Abstract
PURPOSE To investigate the dosimetric accuracy of commercial treatment planning systems used in intensity-modulated radiotherapy (IMRT) for thoracic cancer. METHODS AND MATERIALS Clinical IMRT plans for lung and esophageal cancers and mesothelioma were used to investigate the accuracy of dose calculations from two commercial treatment planning systems (Pinnacle and Corvus systems). Dose distributions were measured with ion chambers and thermoluminescent dosimeters for individual IMRT fields and composite treatment plans in water phantoms and anthropomorphic phantoms. A Monte Carlo-based system was established to compute three-dimensional dose distributions to compare with the treatment planning system calculations. RESULTS Dose calculations from the Pinnacle system were acceptable within 5% of the local dose or a 5-mm distance-to-agreement for 80% of the points measured with ion chambers, 74% of the points measured with thermoluminescent dosimeters, and 96% of the points compared with the Monte Carlo calculations. For the Corvus system, 89% of the points agreed with the measured dose and 98% agreed with the Monte Carlo calculations. Underestimation of the dose from the treatment planning system was found in the low-dose regions (<50% of the prescribed dose), possibly caused by inadequate modeling of the multileaf collimators. CONCLUSION The Pinnacle and Corvus dose calculations were acceptable for thoracic IMRT in high-dose regions. Beam modeling is likely the most critical factor for the accuracy of IMRT dose calculations.
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Affiliation(s)
- Si Young Jang
- Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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