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Radiation dosimetry effect evaluation of a carbon fiber couch on novel uRT-linac 506c accelerator. Sci Rep 2021; 11:13504. [PMID: 34188139 PMCID: PMC8242010 DOI: 10.1038/s41598-021-92836-2] [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: 07/04/2020] [Accepted: 06/14/2021] [Indexed: 11/19/2022] Open
Abstract
Recently, a diagnostic helical CT is integrated into a linear accelerator, called uRT-linac 506c, whose CT scanning dataset can be directly used to do simulation. This novel structure provides a possibility for online adaptive radiotherapy. For adaptive radiotherapy, the carbon fiber couch is an essential external device for supporting and positioning patients. And the effect on dose attenuation and distribution caused by a couch is inevitable and vital for precise treatment. In this research, the couch equipped with uRT-linac 506c was evaluated on the radiation dosimetry effect. The treatment couch equipped on the uRT-linac 506c accelerator was evaluated, and its effect on the attenuation, surface dose and dose buildup were measured for different phantom positions (offset = 0 cm, offset = + 10 cm and offset = − 10 cm, respectively) and different gantry angles. Since uRT-linac 506c is exclusively capable to provide diagnostic CT scanning data with real relative electron density (RED), this CT scanning data of the couch can be used directly in uRT-TPS to design plans. This scanned couch dataset was designated as the model A. The model B was a dummy structure of a treatment couch inserted with artificially preset RED. The dose calculation accuracy of these two models was compared using PB, CC, and MC on uRT-TPS. With the effect of carbon fiber couch, the surface dose was increased at least 97.94% for 25 × 25 cm2 field and 188.83% for 10 × 10 cm2 field, compared with those without. At different phantom positions (offset = 0, + 10, − 10 cm), the attenuation for 6 MV photon beam at gantry angle 180° were 4.4%, 4.4%, and 4.3%, respectively, and varied with changes of gantry angle. There do exists dose deviation between measurement and TPS calculation with the involvement of treatment couch, among the three algorithms, MC presented the least deviation, and the model A made less and steadier deviation than the model B, showing promising superiority. The attenuation, surface dose, and buildup effects of the carbon fiber couch in this study were measured similarly to most counterparts. The dose deviation calculated based on the couch dataset scanned by the diagnostic helical CT was smaller than those based on a dummy couch. This result suggests that an accelerator equipped with a diagnostic CT, which can help reduce the dose deviation of the carbon fiber couch, is a promising platform for online adaptive radiotherapy.
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Aoyama T, Shimizu H, Isomura T, Kitagawa T, Tanaka K, Kodaira T. [Development of an In-house Couch Model to Improve Dose Attenuation Correction Accuracy for a Couch with Different Thickness in the Superior-inferior Direction]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2019; 75:1125-1134. [PMID: 31631105 DOI: 10.6009/jjrt.2019_jsrt_75.10.1125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
As the couch used in external radiation therapy attenuate radiation by interaction, it is necessary to correct attenuation of radiation by inserting a couch model in the treatment planning systems. For a couch whose thickness is different in the superior-inferior direction, it is possible to perform dose calculations with an error within ±1% by using separate different couch models provided by vendors. However, it is difficult to correct attenuation correction accurately with a single couch model. In this study, we created an in-house couch model which can set couch shape and physical density in detail by acquiring CT images of actual couch. When we performed dose calculation by optimizing the physical densities of in-house and vendor couch, it was found that the difference between the measured and the calculated values can be significantly reduced by using in-house couch model. Additionally, by using in-house couch model, it is found that the dose attenuation can be corrected within ±1% for a couch whose thickness is different in the superior-inferior direction.
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Affiliation(s)
- Takahiro Aoyama
- Department of Radiation Oncology, Aichi Cancer Center Hospital
| | - Hidetoshi Shimizu
- Department of Radiation Oncology, Aichi Cancer Center Hospital.,Graduate School of Radiological Technology, Gunma Prefectural College of Health Sciences
| | - Taiki Isomura
- Department of Radiation Oncology, Aichi Cancer Center Hospital (Current address: Department of Proton Technology, Medipolis Proton Therapy and Research Center)
| | - Tomoki Kitagawa
- Department of Radiation Oncology, Aichi Cancer Center Hospital
| | - Kento Tanaka
- Department of Radiation Oncology, Aichi Cancer Center Hospital (Current address: Department of Radiology, Okazaki City Hospital)
| | - Takeshi Kodaira
- Department of Radiation Oncology, Aichi Cancer Center Hospital
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Bawazeer O, Herath S, Sarasanandarajah S, Kron T, Dunn L, Deb P. A simple and efficient method to measure beam attenuation through a radiotherapy treatment couch and immobilization devices. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2019; 42:1183-1189. [PMID: 31452056 DOI: 10.1007/s13246-019-00789-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 08/09/2019] [Indexed: 11/29/2022]
Abstract
We propose a simple and efficient method to measure beam attenuation in one or two dimensions using an amorphous silicon electronic portal imaging device (a-Si EPID). The proposed method was validated against ionization chamber measurements. Beam attenuation through treatment couches (Varian Medical Systems) and immobilization devices (CIVCO Radiotherapy, USA) was examined. The dependency of beam attenuation on field size, photon energy, thickness of the couch, and the presence of a phantom were studied. Attenuation images were derived by computing the percentage difference between images obtained without and with a couch or immobilization devices determining the percentage of attenuation at the center and the mean attenuation. The beam attenuation measurements obtained with an a-Si EPID and an ionization chamber agreed to within ± 0.10 to 1.80%. No difference was noted between the center and mean of an attenuated image for a small field size of 5 × 5 cm2, whereas a large field size of 15 × 15 cm2 exhibited differences of up to 1.13%. For an 18 MV beam, the a-Si EPID required additional build-up material for accurate assessment of beam attenuation. The a-Si EPID could measure differences in beam attenuation through an image guided radiotherapy (IGRT) couch regardless of the variabilities in couch thickness. Interestingly, the addition of a phantom reduced the magnitude of attenuation by approximately 1.20% for a field size of 15 × 15 cm2. A simple method is proposed that provides the user with beam attenuation data in either 2D or 1D within a few minutes.
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Affiliation(s)
- Omemh Bawazeer
- Discipline of Medical Radiations, RMIT University, Melbourne, Australia. .,Discipline of Sciences, Umm Al-Qura University, Mecca, Saudi Arabia.
| | - Sisira Herath
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia
| | - Sivananthan Sarasanandarajah
- Discipline of Medical Radiations, RMIT University, Melbourne, Australia.,Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia.,Department of Medical Imaging and Radiation Sciences, Monash University, Melbourne, Australia
| | - Tomas Kron
- Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, Australia.,Sir Peter MacCallum Cancer Institute, University of Melbourne, Melbourne, Australia
| | - Leon Dunn
- Epworth Radiation Oncology, Epworth Hospital, Melbourne, Australia
| | - Pradip Deb
- Discipline of Medical Radiations, RMIT University, Melbourne, Australia
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Zhang R, Gao Y, Bai W. Quantification and comparison the dosimetric impact of two treatment couch model in VMAT. J Appl Clin Med Phys 2017; 19:10-16. [PMID: 29094802 PMCID: PMC5768035 DOI: 10.1002/acm2.12206] [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: 04/06/2017] [Revised: 07/20/2017] [Accepted: 07/24/2017] [Indexed: 11/15/2022] Open
Abstract
The use of Monte Carlo treatment planning systems (TPS) in radiation therapy has increased the dosimetric accuracy of VMAT treatment sequences. However, this accuracy is compromised by not including the treatment couch into the treatment planning process. Therefore, the impact of the treatment couch on radiation delivery output was determined, and two different couch models (uniform couch model A vs two components model B) were included and tested in the Monaco TPS to investigate which model can better quantify the couch influence on radiation dose. Relative attenuation measurements were performed following procedures outlined by TG‐176 with three phantom positions for A–B direction: on the left half (L), in the center (C) and on the right half (R) of the couch. As well as absolute dose comparison of static fields of 10 × 10 cm2 that were delivered through the couch tops with that calculated in the TPS with the couch model at 2 mm and 5 mm computing grid size respectively. The most severe percentage deviation was 4.60% for the phantom positioned at the left half of the couch with 5 mm grid size at gantry angle 120°. The couch model was included in the TPS with a uniform ED of 0.26 g/cm3 or a two component model with a fiber 0.52 g/cm3 and foam core 0.1 g/cm3. After including the treatment couch, the maximum mean dose attenuation was reduced from 3.68% without couch included to (0.60, 0.83, 0.72, and 1.02) % for model A and model B at 2 and 5 mm voxel grid size. The results obtained showed that Model A performed better than the model B, demonstrating lower deviations from measurements and better robustness against dose grid resolution changes. Considering the results of this study, we propose the systematic introduction of the couch Model A in clinical routine. All the reported findings are valid for the Elekta iBEAM® evo Extension 415 couch and these methods can also be used for other couch model.
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Affiliation(s)
- Ruohui Zhang
- Department of Biomedical Engineering, Tianjin University, Tianjin, China.,Department of Radiation Oncology, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China
| | - Yulan Gao
- Department of Gastroenterology, Hebei General Hospital, Shijiazhuang, China
| | - Wenwen Bai
- Department of Radiation Oncology, The Fourth Hospital of Hebei Medical University, Shijiazhuang, China
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Yu CY, Chou WT, Liao YJ, Lee JH, Liang JA, Hsu SM. Impact of radiation attenuation by a carbon fiber couch on patient dose verification. Sci Rep 2017; 7:43336. [PMID: 28240236 PMCID: PMC5327409 DOI: 10.1038/srep43336] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 01/25/2017] [Indexed: 11/09/2022] Open
Abstract
The aim of this study was to understand the difference between the measured and calculated irradiation attenuations obtained using two algorithms and to identify the influence of couch attenuation on patient dose verification. We performed eight tests of couch attenuation with two photon energies, two longitudinal couch positions, and two rail positions. The couch attenuation was determined using a radiation treatment planning system. The measured and calculated attenuations were compared. We also performed 12 verifications of head-and-neck and rectum cases by using a Delta phantom. The dose deviation (DD), distance to agreement (DTA), and gamma index of pencil-beam convolution (PBC) verifications were nearly the same. The agreement was least consistent for the anisotropic analytical algorithm (AAA) without the couch for the head-and-neck case, in which the DD, DTA, and gamma index were 74.4%, 99.3%, and 89%, respectively; for the rectum case, the corresponding values were 56.2%, 95.1%, and 92.4%. We suggest that dose verification should be performed using the following three metrics simultaneously: DD, DTA, and the gamma index.
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Affiliation(s)
- Chun-Yen Yu
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, ROC.,Medical Physics and Radiation Measurements Laboratory, Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,3Department of Biomedical Imaging and Radiological Science, China Medical University, Taichung, Taiwan, ROC
| | - Wen-Tsae Chou
- Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu, Taiwan, ROC
| | - Yi-Jen Liao
- School of Medical Laboratory Science and Biotechnology, Collage of Medical Science and Technology, Taipei Medical University, Taipei, Taiwan, ROC
| | - Jeng-Hung Lee
- Health Physics Division, Institute of Nuclear Energy Research, Longtan, Taiwan, ROC
| | - Ji-An Liang
- Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan, ROC
| | - Shih-Ming Hsu
- Medical Physics and Radiation Measurements Laboratory, Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan, ROC
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Sheykhoo A, Abdollahi S, Hadizadeh Yazdi MH, Ghorbani M, Mohammadi M. Effects of Siemens TT-D carbon fiber table top on beam attenuation, and build up region of 6 MV photon beam. Rep Pract Oncol Radiother 2017; 22:19-28. [PMID: 27790074 PMCID: PMC5071548 DOI: 10.1016/j.rpor.2016.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 06/29/2016] [Accepted: 09/01/2016] [Indexed: 10/20/2022] Open
Abstract
AIM This study deals with Monte Carlo simulations of the effects which the 550 TXT carbon fiber couch can have on the relevant parameters of a 6 MV clinical photon beam in three field sizes. BACKGROUND According to the reports issued by the International Commission on Radiation Units and Measurements (ICRU), the calculated dose across a high gradient distribution should be within 2% of the relative dose, or within 0.2 cm of the isodose curve position in the target volume. Nowadays, the use of posterior oblique beam has become a common practice. It is clear that, in radiotherapy, the presence of the couch affects the beam intensity and, as a result, the skin dose. MATERIALS AND METHODS Firstly, Siemens linear accelerator validation for 6 MV photon beam was performed, and satisfactory agreement between Monte Carlo and experimental data for various field sizes was observed. Secondly, the couch transmission factor for the reference field size and depth was computed, and the skin dose enhancement by the couch was assessed. RESULTS The largest impact of the carbon fiber couch effect was observed for the 5 × 5 cm2 field size. Such evaluation has not been reported for this couch before. CONCLUSION Despite providing minimal attenuation for the primary radiation, the assumption that carbon fiber couches are radiotranslucent is not valid, and the effects of couches of this type on the transmission factor, and on the skin dose should be carefully investigated for each field size and depth.
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Affiliation(s)
- Asma Sheykhoo
- Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
- Medical Physics Department, Reza Radiation Oncology Center, Mashhad, Iran
| | - Sara Abdollahi
- Medical Physics Department, Reza Radiation Oncology Center, Mashhad, Iran
| | | | - Mahdi Ghorbani
- Medical Physics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Mohammadi
- Department of Medical Physics, Faculty of Medicine, Hamadan University of Medical Sciences, Hamadam, Iran
- Department of Medical Physics, Royal Adelaide Hospital, Adelaide, South Australia, Australia
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Radiotherapy couches: is kevlar an obstacle? Attenuation study of three different tabletops. JOURNAL OF RADIOTHERAPY IN PRACTICE 2016. [DOI: 10.1017/s1460396916000297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractIntroductionTreatment tabletops are usually made of carbon fibre due to its high mechanical strength and rigidity, low specific density, extremely light and regularly considered radiotranslucent. Our clinic acquired a Calypso 4D Localization System where electromagnetic (EM) frequencies to detect implanted transponders in the patient are used. Carbon fibre is an electrical conductive material which interferes with EM frequencies. Therefore, in order to be able to use the Calypso System the carbon fibre tabletop in the treatment room must be replaced. It is our goal to determine the attenuation of the new, non-carbon fibre, tabletop in treatment delivery.Materials and MethodsMeasurements were performed using an ionisation chamber inserted in a slab phantom positioned at the isocenter for 6, 10 MV, 6 and 10 flattening filter free (FFF) MV photon beams. These measurements were performed with and without tabletop for 0°, 30° and 60° beam angle for a True Beam STx linac, for 5×5 cm2 and 10×10 cm2 field size beams. The attenuation was calculated for each measurement for each tabletop.ResultsAt 0° incidence on the Exact IGRT Couch, the measured attenuation for 10×10 cm2 was 2·8 and 2·1% for 6 and 10 MV beams, respectively. For the same field size was measured 3·3 and 2·6% attenuation for 6 and 10 FFF MV beams, respectively. At the same incidence and regarding the other tabletops, the calculated attenuation is lower. For 10×10 cm2 field, there is 2·0, 1·4, 2·1 and 2·6% attenuation for 6, 10 MV, 6 and 10 FFF MV energy beams on the kVueTM Universal Couch. For the KvueTM Calypso® Couch 10×10 cm2 irradiation field, the measurements were 1·6, 1·3, 1·9 and 1·5%, respectively. This tendency is observed for all gantry angles.DiscussionThe attenuation outputs were definitely higher for the Varian Exact IGRT Couch when compared with the kVue tabletops. The attenuation measurements for the kVue tabletops were closer to each other. Nevertheless kVueTM Calypso® Varian tabletop showed smaller mean attenuation of the beams than kVueTM Universal Tip Insert for all measurements.ConclusionsThere was no loss in treatment quality administration due to beam attenuation in the tabletop when tabletops were exchanged because of Calypso system integration. There is no need to change between kVue tabletops whenever there is a regular treatment or a Calypso System guided treatment.
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Gul A, Liaquat M, Kanwal A, Abbasi NZ, Kakakhel MB, Ali A. Assessment of dose error due to nylon mesh of treatment couch. Phys Med 2015; 31:1080-1084. [DOI: 10.1016/j.ejmp.2015.08.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Revised: 08/02/2015] [Accepted: 08/10/2015] [Indexed: 11/28/2022] Open
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Olch AJ, Gerig L, Li H, Mihaylov I, Morgan A. Dosimetric effects caused by couch tops and immobilization devices: Report of AAPM Task Group 176. Med Phys 2014; 41:061501. [DOI: 10.1118/1.4876299] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Foo J, Stensmyr R. Depth dose comparison of measured and calculated dose for the Eclipse virtual carbon couch top models with air gap variation. AUSTRALASIAN PHYSICAL & ENGINEERING SCIENCES IN MEDICINE 2013; 36:457-63. [PMID: 24132584 DOI: 10.1007/s13246-013-0224-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/08/2013] [Indexed: 11/26/2022]
Abstract
This study assessed the accuracy of Eclipse™ (Varian Medical Systems, Palo Alto, CA, USA) treatment planning system (TPS) dose calculations when using virtual couch top models to account for couch presence in patient treatments. The Flat panel and Unipanel couch tops for the Varian Exact Couch were used in this study. Assigned Hounsfield unit (HU) for the virtual couch tops were varied and TPS calculated dose was compared to measured data to determine an optimal assigned HU. Air gaps of up to 10 cm were introduced between couch and phantom to assess the ability of the models to replicate dose in this situation, commonly seen clinically. Dose was measured at a range of depths, for each air gap thickness, in order to assess the model both near surface and at various depths beyond the dose maximum. Optimal HU was taken to be that which had the best agreement between measured and calculated dose over the range of gaps and depths tested. For the Flat panel couch top this was found to be -500 HU and for the Unipanel couch top, -200 HU. Default HU parameters originally set in the models was found to be not optimal for the whole range of depths studied. With optimal HU parameters set, there was good agreement between calculated and measured dose for depths greater than 0.5 cm, but discrepancies were still observed near surface. When implementing virtual couch top models, users could improve dose calculation accuracy by determining the optimal HU from comparisons over several clinical depths rather than a single depth.
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Affiliation(s)
- Jacqueline Foo
- Nepean Cancer Care Centre, Nepean Hospital, Cnr Great Western Highway and Somerset St, Kingswood, NSW, 2747, Australia,
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Kinhikar RA, Pandey VP, Jose RK, Mahantshetty U, Dhote DS, Deshpande DD, Shrivastava SK. Investigation on the effect of sharp phantom edges on point dose measurement during patient-specific dosimetry with Rapid Arc. J Med Phys 2013; 38:139-42. [PMID: 24049321 PMCID: PMC3775038 DOI: 10.4103/0971-6203.116373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/18/2013] [Accepted: 07/05/2013] [Indexed: 11/21/2022] Open
Abstract
The objective of this work was to investigate and quantify the effect of sharp edges of the phantom on the point dose measurement during patient-specific dosimetry with Rapid Arc (RA). Ten patients with carcinoma of prostate were randomly selected for this dosimetric study. Rapid Arc plans were generated with 6 MV X-rays in the Eclipse (v 8.6.14) with single arc (clockwise). Dosimetry verification plans were generated for two phantoms (cylindrical and rectangular). The cylindrical phantom was solid water (diameter 34 cm) and the rectangular phantom was a water phantom (25 cm × 25 cm × 10 cm). These phantoms were pre-scanned in computed tomography (CT) machine with cylindrical ionization chamber (FC65) in place. The plans were delivered with Novalis Tx linear accelerator with 6 MV X-rays for both the phantoms separately. The measured dose was compared with the planned dose for both the phantoms. Mean percentage deviation between measured and planned doses was found to be 4.19 (SD 0.82) and 3.63 (SD 0.89) for cylindrical and rectangular phantoms, respectively. No significant dosimetric variation was found due to the geometry (sharp edges) of the phantom. The sharp edges of the phantom do not perturb the patient specific Rapid Arc dosimetry significantly.
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Affiliation(s)
- R A Kinhikar
- Department of Medical Physics, Tata Memorial Hospital, Mumbai, India
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Pair ML, Du W, Rojas HD, Kanke JE, McGuire SE, Lee AK, Kuban DA, Kudchadker RJ. Dosimetric effects of weight loss or gain during volumetric modulated arc therapy and intensity-modulated radiation therapy for prostate cancer. Med Dosim 2013; 38:251-4. [DOI: 10.1016/j.meddos.2013.02.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 01/28/2013] [Accepted: 02/19/2013] [Indexed: 11/29/2022]
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Zou W, Betancourt R, Yin L, Metz J, Avery S, Kassaee A. Effects on the photon beam from an electromagnetic array used for patient localization and tumor tracking. J Appl Clin Med Phys 2013; 14:4138. [PMID: 23652247 PMCID: PMC5714422 DOI: 10.1120/jacmp.v14i3.4138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 01/08/2013] [Indexed: 11/23/2022] Open
Abstract
One of the main components in a Calypso 4D localization and tracking system is an electromagnetic array placed above patients that is used for target monitoring during radiation treatment. The beam attenuation and beam spoiling properties of the Calypso electromagnetic array at various beam angles were investigated. Measurements were performed on a Varian Clinac iX linear accelerator with 6 MV and 15 MV photon beams. The narrow beam attenuation properties were measured under a field size of 1 cm × 1 cm, with a photon diode placed in a cylindrical graphite buildup cap. The broad beam attenuation properties were measured under a field size of 10 cm × 10 cm, with a 0.6 cc cylindrical Farmer chamber placed in a polystyrene buildup cap. Beam spoiling properties of the array were studied by measuring depth-dose change from the array under a field size of 10 cm × 10 cm in a water-equivalent plastic phantom with an embedded Markus parallel plate chamber. Change in depth doses were measured with the array placed at distances of 2, 5, and 10 cm from the phantom surface. Narrow beam attenuation and broad beam attenuation from the array were found to be less than 2%-3% for both 6 MV and 15 MV beams at angles less than 40°, and were more pronounced at more oblique angles. Spoiling effects are appreciable at beam buildup region, but are insignificant at depths beyond dmax. Dose measurements in a QA phantom using patient IMRT and VMAT treatment plans were shown to have less than 2.5% dose difference with the Calypso array. The results indicate that the dose difference due to the placement of Calypso array is clinically insignificant.
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Affiliation(s)
- Wei Zou
- Department of Radiation Oncology, Cancer Institute of New Jersey, New Brunswick, NJ 08903, USA.
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Tominaga H, Araki F, Shimohigashi Y, Kanetake N, Tomiyama Y, Kawasaki K, Iwashita Y, Sakata J, Okuda T. [Dose impact of a carbon fiber couch for stereotactic body radiation therapy of lung tumors]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2013; 69:400-6. [PMID: 23609862 DOI: 10.6009/jjrt.2013_jsrt_69.4.400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The aim of this study was to measure the dose attenuation caused by a carbon fiber radiation therapy table (Imaging Couch Top; ICT, BrainLab) and to evaluate the dosimetric impact of ICT during stereotactic body radiation therapy (SBRT) in lung tumors. The dose attenuation of ICT was measured using an ionization chamber and modeled by means of a treatment planning system (TPS). SBRT was planned with and without ICT in a lung tumor phantom and ten cases of clinical lung tumors. The results were analyzed from isocenter doses and a dose-volume histogram (DVH): D95, Dmean, V20, V5, homogeneity index (HI), and conformity index (CI). The dose attenuation of the ICT modeled with TPS agreed to within ±1% of the actually measured values. The isocenter doses, D95 and Dmean with and without ICT showed differences of 4.1-5% for posterior single field and three fields in the phantom study, and differences of 0.6-2.4% for five fields and rotation in the phantom study and six fields in ten clinical cases. The dose impact of ICT was not significant for five or more fields in SBRT. It is thus possible to reduce the dose effect of ICT by modifying the beam angle and beam weight in the treatment plan.
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Inverse planned constant dose rate volumetric modulated arc therapy (VMAT) as an efficient alternative to five-field intensity modulated radiation therapy (IMRT) for prostate. JOURNAL OF RADIOTHERAPY IN PRACTICE 2013. [DOI: 10.1017/s1460396913000083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractPurposeThe aim of this work was to determine if volumetric modulated arc therapy (VMAT) plans, created for constant dose-rate (cdrVMAT) delivery are a viable alternative to step and shoot five-field intensity modulated radiation therapy (IMRT).Materials and methodsThe cdrVMAT plans, inverse planned on a treatment planning system with no solution to account for couch top or rails, were created for delivery on a linear accelerator with no variable dose rate control system. A series of five-field IMRT and cdrVMAT plans were created using dual partial arcs (gantry rotating between 260° and 100°) with 4° control points for ten prostate patients with the average rectal constraint incrementally increased. Pareto fronts were compared for the planning target volume homogeneity and average rectal dose between the two techniques for each patient. Also investigated were tumour control probability and normal tissue complication probability values for each technique. The delivery parameters [monitor units (MU) and time] and delivery accuracy of the IMRT and VMAT plans were also compared.ResultsPareto fronts showed that the dual partial arc plans were superior to the five-field IMRT plans, particularly for the clinically acceptable plans where average rectal doses were less for rotational plans (p = 0·009) with no statistical difference in target homogeneity. The cdrVMAT plans had significantly more MU (p = 0·005) but the average delivery time was significantly less than the IMRT plans by 42%. All clinically acceptable cdrVMAT plans were accurate in their delivery (gamma 99·2 ± 1·1%, 3%3 mm criteria).ConclusionsAccurate delivery of dual partial arc cdrVMAT avoiding the couch top and rails has been demonstrated.
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Njeh CF, Parker J, Spurgin J, Rhoe E. A validation of carbon fiber imaging couch top modeling in two radiation therapy treatment planning systems: Philips Pinnacle3 and BrainLAB iPlan RT Dose. Radiat Oncol 2012; 7:190. [PMID: 23140425 PMCID: PMC3549905 DOI: 10.1186/1748-717x-7-190] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/25/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Carbon fiber (CF) is now the material of choice for radiation therapy couch tops. Initial designs included side metal bars for rigidity; however, with the advent of IGRT, involving on board imaging, new thicker CF couch tops without metal bars have been developed. The new design allows for excellent imaging at the expense of potentially unacceptable dose attenuation and perturbation. OBJECTIVES We set out to model the BrainLAB imaging couch top (ICT) in Philips Pinnacle(3) treatment planning system (TPS), to validate the already modeled ICT in BrainLAB iPlan RT Dose treatment planning system and to compute the magnitude of the loss in skin sparing. RESULTS Using CF density of 0.55 g/cm(3) and foam density of 0.03 g/cm(3), we demonstrated an excellent agreement between measured dose and Pinnacle(3) TPS computed dose using 6 MV beam. The agreement was within 1% for all gantry angle measured except for 120°, which was 1.8%. The measured and iPlan RT Dose TPS computed dose agreed to within 1% for all gantry angles and field sizes measured except for 100° where the agreement was 1.4% for 10 cm × 10 cm field size. Predicted attenuation through the couch by iPlan RT Dose TPS (3.4% - 9.5%) and Pinnacle(3) TPS (2% - 6.6%) were within the same magnitude and similar to previously reported in the literature. Pinnacle(3) TPS estimated an 8% to 20% increase in skin dose with increase in field size. With the introduction of the CF couch top, it estimated an increase in skin dose by approximately 46 - 90%. The clinical impact of omitting the couch in treatment planning will be dependent on the beam arrangement, the percentage of the beams intersecting the couch and their angles of incidence. CONCLUSION We have successfully modeled the ICT in Pinnacle(3) TPS and validated the modeled ICT in iPlan RT Dose. It is recommended that the ICT be included in treatment planning for all treatments that involve posteriors beams. There is a significant increase in skin dose that is dependent on the percentage of the beam passing through the couch and the angle of incidence.
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