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Gill A, Hirst AL, Rowshanfarzad P, Gill S, Bucknell N, Dass J, Sabet M. Stereotactic body radiotherapy for early-stage lung cancer: a systematic review on the choice of photon energy and linac flattened/unflattened beams. Radiat Oncol 2024; 19:1. [PMID: 38167095 PMCID: PMC10762943 DOI: 10.1186/s13014-023-02392-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 12/15/2023] [Indexed: 01/05/2024] Open
Abstract
SBRT is an effective local treatment for patients with early-stage non-small cell lung cancer (NSCLC). This treatment is currently used in patients who have poor lung function or who decline surgery. As SBRT usually has small PTV margins, reducing the beam-on-time (BOT) is beneficial for accurate dose delivery by minimising intrafraction motion as well as improved patient comfort. Removal of the linear accelerator flattening filter can provide a higher dose rate which results in a faster treatment. In addition, the choice of photon energy can also affect the dose distribution to the target and the organs-at-risk (OAR). In this systematic review, studies analysing the choice of various photon beam energies, with a flattening filter or flattening filter free (FFF), were compared for their overall dosimetric benefit in the SBRT treatment for early-stage NSCLC. It was found that FFF treatment delivers a comparatively more conformal dose distribution, as well as a better homogeneity index and conformity index, and typically reduces BOT by between 30 and 50%. The trade-off may be a minor increase in monitor units for FFF treatment found in some studies but not others. Target conformity and OAR sparing, particularly lung doses appear better with 6MV FFF, but 10MV FFF was marginally more advantageous for skin sparing and BOT reduction. The favourable beam modality for clinical use would depend on the individual case, for which tumour size and depth, radiotherapy technique, as well as fractionation scheme need to be taken into account.
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Affiliation(s)
- Ashlesha Gill
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia.
| | - Andrew L Hirst
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Pejman Rowshanfarzad
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Suki Gill
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Nicholas Bucknell
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Joshua Dass
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
| | - Mahsheed Sabet
- School of Physics, Mathematics and Computing, The University of Western Australia, Crawley, WA, 6009, Australia
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Nedlands, WA, 6009, Australia
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Fu C, Xu X, Zheng C, Liu X, Zhao D, Qiu W. Photocatalysis of aqueous PFOA by common catalysts of In 2O 3, Ga 2O 3, TiO 2, CeO 2 and CdS: influence factors and mechanistic insights. Environ Geochem Health 2022; 44:2943-2953. [PMID: 35064382 DOI: 10.1007/s10653-021-01127-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 10/09/2021] [Indexed: 06/14/2023]
Abstract
Gallium oxide (Ga2O3), titanium dioxide (TiO2), cerium dioxide (CeO2), indium oxide (In2O3) and cadmium sulfide (CdS) were commonly used under UV light as photocatalysis system for the pollutants' degradation. In this study, these five catalysts were applied for the photodegradation of perfluorooctanoic acid (PFOA), a well-known perfluoroalkyl substance (PFAS). As a result, the PFOA photodegradation performance was sequenced as: Ga2O3 > TiO2 > CeO2 > In2O3 > CdS. To further explain the photocatalysis mechanism, the effects of initial pH, photon energy and band gap were evaluated. The initial pH of 3 ± 0.2 hinders the catalytic reaction of CdS, resulting in low degradation of PFOA, while it has no significant effect on Ga2O3, TiO2, CeO2 and In2O3. In addition, quantum yield was sequenced as TiO2 > CeO2 > Ga2O3 > In2O3, which may not be the main factor determining the degradation effect. Notably, the band gap energy from large to narrow was as: Ga2O3 > TiO2 > CeO2 > In2O3 > CdS, which exactly matched their degradation performance.
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Affiliation(s)
- Caixia Fu
- School of Environment, Harbin Institute of Technology, Harbin, 150090, China
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiuru Xu
- School of Agricultural and Biological Technology, Wenzhou Vocational College of Science & Technology, Zhejiang, 325006, China.
| | - Chunmiao Zheng
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xinjie Liu
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Dandan Zhao
- Department of Built Environment, Aalto University, PO Box 15200, 00076, Espoo, Finland
| | - Wenhui Qiu
- School of Public Health and Emergency Management, Southern University of Science and Technology, Shenzhen, 518055, China.
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Szlazak K, Vass V, Hasslinger P, Jaroszewicz J, Dejaco A, Idaszek J, Scheiner S, Hellmich C, Swieszkowski W. X-ray physics-based CT-to-composition conversion applied to a tissue engineering scaffold, enabling multiscale simulation of its elastic behavior. Mater Sci Eng C Mater Biol Appl 2017; 95:389-396. [PMID: 30573263 DOI: 10.1016/j.msec.2017.11.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 09/05/2017] [Accepted: 11/29/2017] [Indexed: 12/13/2022]
Abstract
Nowadays, the assessment of the mechanical competence of tissue engineering scaffolds based on computer simulations is a well-accepted technology. Typically, such simulations are performed by means of the Finite Element (FE) method, with the underlying structural model being created based on micro-computed tomography (microCT). Here, this analysis modality is applied to a new, ternary composite, consisting of PHBV, i.e. poly(3-hydroxybutyrate-co-3-hydroxyvalerate), PLGA, i.e. poly(lactic-co-glycolide), as well as of TCP, i.e. tricalcium phosphate hydrate. The studied scaffold structure is made up by fibers of this new composite material, manufactured by means of the rapid prototyping method. The data collected from microCT is utilized for adequately defining the mechanical properties of the FE model. In particular, the three-dimensional field of grey values is interpreted in terms of the underlying field of attenuation coefficients, taking into account the photon energy employed in microCT imaging, eventually allowing for calculation of the three-dimensionally distributed, voxel-specific composition of the studied material. For the sake of keeping the FE simulations as efficient as possible, groups of voxels are combined into one finite element; the grey value of the latter is obtained by volume averaging. Employing a two-step micromechanical homogenization scheme, the experimentally accessible stiffness of the three constituents (PHBV, PLGA, and TCP) is then, finite element by finite element, upscaled to the composition-dependent stiffness of the composite material. The plausibility and adequacy of the FE model is demonstrated by simulating the effects of uniaxial compression on the scaffold structure, in terms of resulting stress and strain fields, highlighting the importance of the fiber junctions (as they are the mechanically most stressed regions), and that neglecting the material heterogeneity would lead to a potentially significant underestimation of stresses and strains. Finally, a comparison is made of the employed analysis modality of microCT data with a previously pursued, simplified analysis strategy, highlighting the conceptual superiority of the former, and pointing out the application limits of the latter.
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Affiliation(s)
- Karol Szlazak
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland
| | - Viktoria Vass
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| | - Patricia Hasslinger
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| | - Jakub Jaroszewicz
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland
| | - Alexander Dejaco
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| | - Joanna Idaszek
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland
| | - Stefan Scheiner
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria.
| | - Christian Hellmich
- Institute for Mechanics of Materials and Structures, TU Wien - Vienna University of Technology, Vienna, Austria
| | - Wojciech Swieszkowski
- Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland
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Hauri P, Schneider U. Whole-body dose and energy measurements in radiotherapy by a combination of LiF:Mg,Cu,P and LiF:Mg,Ti. Z Med Phys 2017; 28:96-109. [PMID: 28807441 DOI: 10.1016/j.zemedi.2017.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 06/07/2017] [Accepted: 07/09/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE Long-term survivors of cancer who were treated with radiotherapy are at risk of a radiation-induced tumor. Hence, it is important to model the out-of-field dose resulting from a cancer treatment. These models have to be verified with measurements, due to the small size, the high sensitivity to ionizing radiation and the tissue-equivalent composition, LiF thermoluminescence dosimeters (TLD) are well-suited for out-of-field dose measurements. However, the photon energy variation of the stray dose leads to systematic dose errors caused by the variation in response with radiation energy of the TLDs. We present a dosimeter which automatically corrects for the energy variation of the measured photons by combining LiF:Mg,Ti (TLD100) and LiF:Mg,Cu,P (TLD100H) chips. METHODS The response with radiation energy of TLD100 and TLD100H compared to 60Co was taken from the literature. For the measurement, a TLD100H was placed on top of a TLD100 chip. The dose ratio between the TLD100 and TLD100H, combined with the ratio of the response curves was used to determine the mean energy. With the energy, the individual correction factors for TLD100 and TLD100H could be found. The accuracy in determining the in- and out-of-field dose for a nominal beam energy of 6MV using the double-TLD unit was evaluated by an end-to-end measurement. Furthermore, published Monte Carlo (M.C.) simulations of the mean photon energy for brachytherapy sources, stray radiation of a treatment machine and cone beam CT (CBCT) were compared to the measured mean energies. Finally, the photon energy distribution in an Alderson phantom was measured for different treatment techniques applied with a linear accelerator. Additionally, a treatment plan was measured with a cobalt machine combined with an MRI. RESULTS For external radiotherapy, the presented double-TLD unit showed a relative type A uncertainty in doses of -1%±2% at the two standard deviation level compared to an ionization chamber. The type A uncertainty in dose was in agreement with the theoretically calculated type B uncertainty. The measured energies for brachytherapy sources, stray radiation of a treatment machine and CBCT imaging were in agreement with M.C. simulations. A shift in energy with increasing distance to the isocenter was noticed for the various treatment plans measured with the Alderson phantom. The calculated type B uncertainties in energy were in line with the experimentally evaluated type A uncertainties. CONCLUSION The double-TLD unit is able to predict the photon energy of scatter radiation in external radiotherapy, X-ray imagine and brachytherapy sources. For external radiotherapy, the individual energy correction factors enabled a more accurate dose determination compared to conventional TLD measurements.
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Affiliation(s)
- Pascal Hauri
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland.
| | - Uwe Schneider
- Department of Physics, University of Zurich, Zurich, Switzerland; Radiotherapy Hirslanden, Hirslanden Medical Center, Aarau, Switzerland
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Yadav G, Bhushan M, Dewan A, Saxena U, Kumar L, Chauhan D, Raman K, Mitra S, Suhail M. Dosimetric influence of photon beam energy and number of arcs on volumetric modulated arc therapy in carcinoma cervix: A planning study. Rep Pract Oncol Radiother 2017; 22:1-9. [PMID: 27790072 PMCID: PMC5071544 DOI: 10.1016/j.rpor.2016.09.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 04/05/2016] [Accepted: 09/01/2016] [Indexed: 11/25/2022] Open
Abstract
AIM Aim of the present study was to compare the dosimetric impact of different photon beam energies and number of arcs in the treatment of carcinoma cervix. BACKGROUND Carcinoma cervix is a common cancer in women worldwide with a high morbidity rate. Radiotherapy is used to treat such tumours. Volumetric Modulated Arc Therapy (VMAT) is considered superior to other techniques with multiple arcs and energies. MATERIALS AND METHODS Twenty patients with carcinoma cervix underwent radiotherapy in a prospective observation study conducted at our institute. Volumetric modulated arc plans with 6 MV, 10 MV and 15 MV photon energies using single arc (SA) and dual arc (DA) were generated. Several physical indices for planning target volume (PTV) like V95%, V100%, V110%, D98%, D50%, D2% and total number of MUs were compared. Normal Tissue Integral Dose (NTID) and dose to a shell structure PHY2.5 and PHY5.0 were analyzed. RESULTS Comparable dose coverage to PTV was observed for all the energies and arcs. CI for DA6MV (1.095) was better than SA6MV (1.127), SA10MV (1.116) and SA15MV (1.116). Evaluated parameters showed significant reduction in OAR doses. Mean bladder dose for DA6MV (41.90 Gy) was better than SA6MV (42.48 Gy), SA10MV (42.08 Gy) and SA15MV (41.93 Gy). Similarly, p-value for the mean rectal dose calculated was 0.001 (SA6 vs 15), 0.013 (DA6 vs 10) and 0.003 (DA6 vs 15) and subsequently favoured DA6MV. Difference in NTID was very small. CONCLUSIONS The study showed no greater advantage of higher energy, and DA VMAT plan with 6 MV photon energy was a good choice of treatment for carcinoma cervix as it delivered a highly homogeneous and conformal plan with superior target coverage and better OAR sparing.
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Affiliation(s)
| | - Manindra Bhushan
- Division of Medical Physics & Department of Radiation Oncology, Rajiv Gandhi Cancer Institute and Research Centre, Sector-5, Rohini, New Delhi 110085, India
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Sung W, Park JM, Choi CH, Ha SW, Ye SJ. The effect of photon energy on intensity-modulated radiation therapy (IMRT) plans for prostate cancer. Radiat Oncol J 2012; 30:27-35. [PMID: 23120741 PMCID: PMC3475960 DOI: 10.3857/roj.2012.30.1.27] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 03/05/2012] [Accepted: 03/09/2012] [Indexed: 01/10/2023] Open
Abstract
Purpose To evaluate the effect of common three photon energies (6-MV, 10-MV, and 15-MV) on intensity-modulated radiation therapy (IMRT) plans to treat prostate cancer patients. Materials and Methods Twenty patients with prostate cancer treated locally to 81.0 Gy were retrospectively studied. 6-MV, 10-MV, and 15-MV IMRT plans for each patient were generated using suitable planning objectives, dose constraints, and 8-field setting. The plans were analyzed in terms of dose-volume histogram for the target coverage, dose conformity, organs at risk (OAR) sparing, and normal tissue integral dose. Results Regardless of the energies chosen at the plans, the target coverage, conformity, and homogeneity of the plans were similar. However, there was a significant dose increase in rectal wall and femoral heads for 6-MV compared to those for 10-MV and 15-MV. The V20 Gy of rectal wall with 6-MV, 10-MV, and 15-MV were 95.6%, 88.4%, and 89.4% while the mean dose to femoral heads were 31.7, 25.9, and 26.3 Gy, respectively. Integral doses to the normal tissues in higher energy (10-MV and 15-MV) plans were reduced by about 7%. Overall, integral doses in mid and low dose regions in 6-MV plans were increased by up to 13%. Conclusion In this study, 10-MV prostate IMRT plans showed better OAR sparing and less integral doses than the 6-MV. The biological and clinical significance of this finding remains to be determined afterward, considering neutron dose contribution.
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Affiliation(s)
- Wonmo Sung
- Interdisciplinary Program in Radiation Applied Life Science, Seoul National University College of Medicine, Seoul, Korea. ; Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea
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Tyagi A, Supe SS, Sandeep, Singh MP. A dosimetric analysis of 6 MV versus 15 MV photon energy plans for intensity modulated radiation therapy (IMRT) of carcinoma of cervix. Rep Pract Oncol Radiother 2010; 15:125-31. [PMID: 24376938 DOI: 10.1016/j.rpor.2010.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Revised: 07/23/2010] [Accepted: 08/04/2010] [Indexed: 10/19/2022] Open
Abstract
BACKGROUND Intensity modulated radiotherapy (IMRT) is being used to treat carcinoma of cervix (Ca Cx). Integral dose to normal tissue and increased leakage are the concern about IMRT. 6 MV photon beam is a good choice of energy for Ca Cx IMRT treatment. AIM The objective of this study was to compare intensity modulated radiotherapy (IMRT) plans generated by 6 MV and 15 MV photon energies for carcinoma of cervix (Ca Cx) with regards to dosimetric parameters of planning target volume (PTV) and organs at risk (OAR), homogeneity index (HI), conformity index at 98% level (CI 98%), integral dose to normal tissue (NTID) and total number of monitor units (MUs). MATERIAL AND METHODS A cohort of 16 patients was selected for this study. All patients were to receive a dose of 50 Gy in 25 fractions. IMRT plans were generated for both energies using same dose-volume constraints. RESULTS Our results show a comparable coverage of planning target volume (PTV) for both energies. Volume of PTV receiving a prescription dose is 97.8 ± 0.5% and 98.8 ± 0.4% for the 6 MV and the 15 MV plans. Volume of PTV receiving a dose of 107% is 4.4 ± 7.8% and 16.1 ± 22.2%. Bladder and rectum mean doses for the 6 MV and the 15 MV photon plans were 39.8 ± 3.0 Gy and 40.0 ± 3.2 Gy, and 35.8 ± 3.1 Gy and 36.0 ± 3.1 Gy, respectively. Homogeneity index (HI) for both energies was 1.04. The conformity indices at 98% isodose (CI 98%) were 1.3 ± 0.1 and 1.4 ± 0.1 for 6 MV and 15 MV photon plans, respectively. CONCLUSIONS We conclude that a 6 MV photon is a good choice for Ca Cx IMRT as it produces a highly conformal, homogeneous plan with superior target coverage and better OAR sparing.
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Affiliation(s)
- Atul Tyagi
- Department of Radiation Oncology, BLK Memorial Hospital, New Delhi, India ; Department of Physics, MMH College, Ghaziabad, UP, India
| | - Sanjay S Supe
- Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Bangalore, Karnataka, India
| | - Sandeep
- Department of Radiation Oncology, BLK Memorial Hospital, New Delhi, India
| | - Man P Singh
- Department of Physics, MMH College, Ghaziabad, UP, India
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