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Delbaere A, Younes T, Khamphan C, Vieillevigne L. Experimental validation of absorbed dose-to-medium calculation algorithms in heterogeneous media. Phys Med Biol 2024; 69:055006. [PMID: 38266285 DOI: 10.1088/1361-6560/ad222e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 01/24/2024] [Indexed: 01/26/2024]
Abstract
Objective.The aim of this work was to determine heterogeneous correction factorshQclin,Qreffclin,frefdetm,wto validate absorbed dose-to-mediumDm,Qclinm,fclincalculation algorithms from detector readings. The impact of detector orientation perpendicular and parallel to the beam central axis on the correction factors was also investigated.Approach.ThehQclin,Qreffclin,frefdetm,wfactors were calculated for four types of detectors (PTW PinPoint T31016, PTW microDiamond T60019, PTW microSilicon T60023 and EBT3 film) placed in different media (cortical bone, lung, adipose tissue, Teflon and RW3) for the 6 MV energy beam with a 10 × 10 cm2field size. These corrections were then applied to the detector measurements performed at different depths in heterogeneous phantoms.Main results.ThehQclin,Qreffclin,frefdetm,wfactors mainly depended on the media and slightly on the type of detector. Considering all detectors, the largest corrections were found in high-density media with values ranging from 0.911 to 0.934 in cortical bone. For comparison, the corrections in other media were closer to unity with values from 0.966 (lung and RW3) to 0.991 (adipose tissue). Except for the PinPoint T31016, detector orientation-dependence was observed especially in high-density media. A good agreement (≤1.5%) was found betweenDm,Qclinm,fclincalculations and the detector readings corrected with thehQclin,Qreffclin,frefdetm,wfactor for all studied heterogeneous phantoms.Significance.This paper could serve as an initial guideline for medical physicists involved in the validation of the advanced type-b dose calculation algorithms reportingDm,Qclinm,fclin. To our knowledge, this is the first study to assess the impact of the orientation of different detectors in heterogeneous media. The orientation dependence of the detector response observed in water may not reflect what is observed in heterogeneous media, especially in high-density media. The knowledge of thehQclin,Qreffclin,frefdetm,wfactors becomes mandatory for accurate interpretation of detector readings and comparisons withDm,Qclinm,fclincalculations.
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Affiliation(s)
- Alexia Delbaere
- Department of Medical Physics, Oncopole Claudius Regaud - Institut Universitaire du Cancer de Toulouse, F-31059 Toulouse, France
- Centre de Recherches en Cancérologie de Toulouse, UMR1037 INSERM-Université Toulouse 3-ERL5294 CNRS, Oncopole, F-31037 Toulouse, France
| | - Tony Younes
- Department of Medical Physics, Oncopole Claudius Regaud - Institut Universitaire du Cancer de Toulouse, F-31059 Toulouse, France
- Centre de Recherches en Cancérologie de Toulouse, UMR1037 INSERM-Université Toulouse 3-ERL5294 CNRS, Oncopole, F-31037 Toulouse, France
| | - Catherine Khamphan
- Department of Medical Physics, Institut du Cancer-Avignon Provence, F-84000 Avignon, France
| | - Laure Vieillevigne
- Department of Medical Physics, Oncopole Claudius Regaud - Institut Universitaire du Cancer de Toulouse, F-31059 Toulouse, France
- Centre de Recherches en Cancérologie de Toulouse, UMR1037 INSERM-Université Toulouse 3-ERL5294 CNRS, Oncopole, F-31037 Toulouse, France
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Heng VJ, Serban M, Renaud MA, Freeman C, Seuntjens J. Robust mixed electron-photon radiation therapy planning for soft tissue sarcoma. Med Phys 2023; 50:6502-6513. [PMID: 37681990 DOI: 10.1002/mp.16709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 08/02/2023] [Accepted: 08/20/2023] [Indexed: 09/09/2023] Open
Abstract
BACKGROUND Mixed electron-photon beam radiation therapy (MBRT) is an emerging technique in which external electron and photon beams are simultaneously optimized into a single treatment plan. MBRT exploits the steep dose falloff and high surface dose of electrons while maintaining target conformity by leveraging the sharp penumbra of photons. PURPOSE This study investigates the dosimetric benefits of MBRT for soft tissue sarcoma (STS) patients. MATERIAL AND METHODS A retrospective cohort of 22 STS of the lower extremity treated with conventional photon-based Volumetric Modulated Arc Therapy (VMAT) were replanned with MBRT. Both VMAT and MBRT treatments were planned on the Varian TrueBeam linac using the Millenium multi-leaf collimator. No electron applicator, cutout or additional collimating devices were used for electron beams of MBRT plans. MBRT plans were optimized to use a combination of 6 MV photons and five electron energies (6, 9, 12, 16, 20 MeV) by a robust column generation algorithm. Electron beams in this study were planned at standard 100 cm source-axis distance (SAD). The dose to the clinical target volume (CTV), bone, normal tissue strip and other organs-at-risk (OARs) were compared using a Wilcoxon signed-rank test. RESULTS As part of the original VMAT treatment, tissue-equivalent bolus was required in 10 of the 22 patients. MBRT plans did not require bolus by virtue of the higher electron entrance dose. CTV coverage by the prescription dose was found to be clinically equivalent between plans of either modality:V 50Gy $V_{\text{50Gy}}$ (MBRT) = 97.9 ± 0.2% versusV 50Gy $V_{\text{50Gy}}$ (VMAT) = 98.1 ± 0.6% (p=0.34). Evaluating the absolute paired difference between doses to OARs in MBRT and VMAT plans, we observed lowerV 20Gy $V_{\text{20Gy}}$ to normal tissue in MBRT plans by 14.9 ± 3.2% (p < 10 - 6 $p<10^{-6}$ ). Similarly,V 50Gy $V_{\text{50Gy}}$ to bone was found to be decreased by 8.2 ± 4.0% (p < 10 - 3 $p<10^{-3}$ ) of the bone volume. CONCLUSION For STS with subcutaneous involvement, MBRT offers statistically significant sparing of OARs without sacrificing target coverage when compared to VMAT. MBRT plans are deliverable on conventional linacs without the use of electron applicators, shortened source-to-surface distance (SSD) or bolus. This study shows that MBRT is a logistically feasible technique with clear dosimetric benefits.
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Affiliation(s)
- Veng Jean Heng
- Department of Physics and Medical Physics Unit, McGill University, Montreal, Canada
| | - Monica Serban
- Princess Margaret Cancer Centre and Department of Radiation Oncology, University of Toronto, Toronto, Canada
- Gerald Bronfman Department of Oncology, Medical Physics Unit, McGill University, Montreal, Canada
| | | | | | - Jan Seuntjens
- Princess Margaret Cancer Centre and Department of Radiation Oncology, University of Toronto, Toronto, Canada
- Gerald Bronfman Department of Oncology, Medical Physics Unit, McGill University, Montreal, Canada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
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Decoene C, Crop F. Using density computed tomography images for photon dose calculations in radiation oncology: A patient study. Phys Imaging Radiat Oncol 2023; 27:100463. [PMID: 37497189 PMCID: PMC10366581 DOI: 10.1016/j.phro.2023.100463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/20/2023] [Accepted: 06/20/2023] [Indexed: 07/28/2023] Open
Abstract
Background and purpose Conventional workflows for dose calculations require conversions between Hounsfield Units (HU) and the mass or electron density for Computed Tomography (CT) images in the Treatment Planning System (TPS). These conversions are scanner- and mostly kVp-dependent. A density representation or reconstruction at the CT level can potentially simplify the workflow. This study aimed to investigate the agreement between these two methods for patients and different calculation algorithms. Materials and methods Density conversions for conventional HU-density conversions were first established using two phantoms with appropriate inserts. Next, the differences in density and dose calculations between both methods were assessed using 95% Limits of Agreement (LOA) Bland-Altman analysis for 44 consecutive clinical patient cases. These cases represented a mix of indications, algorithms (collapsed cone, convolution superposition, ray tracing, finite-size pencil beam, and Monte Carlo), and scan kVp (80 to 140) in two different commercial TPS. Results No statistically significant bias in density or dose calculations was found between the two methods. Furthermore, 95% LOAs between both methods were ±0.05 g/cm3 and ±0.1 Gy for density and dose, respectively. Small but clinically irrelevant dose differences were found in high-density gradient regions for convolution superposition calculations or CT scans with non-delayed contrast agent injections with targets nearby vessels. Conclusions The in vivo density-reconstructed images at the CT level were assessed to be equivalent. Therefore, they can simplify and improve clinical workflows, allowing patient-specific acquisitions for contouring and density-reconstructed images for dose calculations.
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Affiliation(s)
- Camille Decoene
- Corresponding author at: Service of Medical physics, Centre Oscar Lambret, 3, Rue Frédéric Combemale, Lille 59000.
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Jurado-Bruggeman D, Muñoz-Montplet C. Considerations for radiotherapy planning with MV photons using dose-to-medium. Phys Imaging Radiat Oncol 2023; 26:100443. [PMID: 37342209 PMCID: PMC10277912 DOI: 10.1016/j.phro.2023.100443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 04/23/2023] [Accepted: 04/25/2023] [Indexed: 06/22/2023] Open
Abstract
Background and purpose Radiotherapy planning considerations were developed for the previous calculation algorithms yielding dose to water-in-water (Dw,w). Advanced algorithms improve accuracy, but their dose values in terms of dose to medium-in-medium (Dm,m) depend on the medium considered. This work aimed to show how mimicking Dw,w planning with Dm,m can introduce new issues. Materials and methods A head and neck case involving bone and metal heterogeneities outside the CTV was considered. Two different commercial algorithms were used to obtain Dm,m and Dw,w distributions. First, a plan was optimised to irradiate the PTV uniformly and get a homogeneous Dw,w distribution. Second, another plan was optimised to achieve homogeneous Dm,m. Both plans were calculated with Dw,w and Dm,m, and the differences between their dose distributions, clinical impact, and robustness were evaluated. Results Uniform irradiation produced Dm,m cold spots in bone (-4%) and implants (-10%). Uniform Dm,m compensated them by increasing fluence but, when recalculated in Dw,w, the fluence compensations produced higher doses that affected homogeneity. Additionally, doses were 1% higher for the target, and + 4% for the mandible, thus increasing toxicity risk. Robustness was impaired when increased fluence regions and heterogeneities mismatched. Conclusion Planning with Dm,m as with Dw,w can impact clinical outcome and impair robustness. In optimisation, uniform irradiation instead of homogeneous Dm,m distributions should be pursued when media with different Dm,m responses are involved. However, this requires adapting evaluation criteria or avoiding medium effects. Regardless of the approach, there can be systematic differences in dose prescription and constraints.
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Affiliation(s)
- Diego Jurado-Bruggeman
- Medical Physics and Radiation Protection Department, Catalan Institute of Oncology Girona, Girona, Spain
| | - Carles Muñoz-Montplet
- Medical Physics and Radiation Protection Department, Catalan Institute of Oncology Girona, Girona, Spain
- Department of Medical Sciences, University of Girona, Girona, Spain
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Kolacio MŠ, Rajlić D, Radojčić M, Radojčić ĐS, Obajdin N, Debeljuh DD, Jurković S. Dosimetric accuracy of three dose calculation algorithms for radiation therapy of in situ non-small cell lung carcinoma. Rep Pract Oncol Radiother 2022; 27:86-96. [PMID: 35402037 PMCID: PMC8989458 DOI: 10.5603/rpor.a2022.0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 01/19/2022] [Indexed: 11/25/2022] Open
Abstract
Background Study determines differences in calculated dose distributions for non-small cell lung carcinoma (NSC LC) patients. NSC LC cases were investigated, being the most common lung cancer treated by radiotherapy in our clinical practice. Materials and methods A retrospective study of 15 NSCLC patient dose distributions originally calculated using standard superposition (SS) and recalculated using collapsed cone (CC ) and Monte Carlo (MC) based algorithm expressed as dose to medium in medium (MCDm) and dose to water in medium (MCDw,) was performed so that prescribed dose covers at least 99% of the gross target volume (GTV). Statistical analysis was performed for differences of conformity index (CI), heterogeneity index (HI), gradient index (GI), dose delivered to 2% of the volume (D2%), mean dose (Dmean) and percentage of volumes covered by prescribed dose (V70Gy). For organs at risk (OARs), Dmean and percentage of volume receiving 20 Gy and 5Gy (V20Gy, V5Gy) were analysed. Results Statistically significant difference for GTVs was observed between MCDw and SS algorithm in mean dose only. For planning target volumes (PTVs), statistically significant differences were observed in prescribed dose coverage for CC, MCDm and MCDw. The differences in mean CI value for the CC algorithm and mean HI value for MCDm and MCDw were statistically significant. There is a statistically significant difference in the number of MUs for MCDm and MCDw compared to SS. Conclusion All investigated algorithms succeed in managing the restrictive conditions of the clinical goals. This study shows the drawbacks of the CC algorithm compared to other algorithms used.
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Affiliation(s)
| | - David Rajlić
- Medical Physics Department, Clinical Hospital Center Rijeka, Rijeka, Croatia
| | - Milan Radojčić
- Clinic for Radiotherapy and Oncology, Clinical Hospital Center Rijeka, Rijeka, Croatia
| | - Đeni Smilović Radojčić
- Medical Physics Department, Clinical Hospital Center Rijeka, Rijeka, Croatia.,Department of Medical Physics and Biophysics, University of Rijeka Faculty of Medicine, Rijeka, Croatia
| | - Nevena Obajdin
- Medical Physics Department, Clinical Hospital Center Rijeka, Rijeka, Croatia
| | - Dea Dundara Debeljuh
- Medical Physics Department, Clinical Hospital Center Rijeka, Rijeka, Croatia.,Department of Medical Physics and Biophysics, University of Rijeka Faculty of Medicine, Rijeka, Croatia.,Radiology Department, General Hospital Pula, Pula, Croatia
| | - Slaven Jurković
- Medical Physics Department, Clinical Hospital Center Rijeka, Rijeka, Croatia.,Department of Medical Physics and Biophysics, University of Rijeka Faculty of Medicine, Rijeka, Croatia
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Feygelman V, Latifi K, Bowers M, Greco K, Moros EG, Isacson M, Angerud A, Caudell J. Maintaining dosimetric quality when switching to a Monte Carlo dose engine for head and neck volumetric-modulated arc therapy planning. J Appl Clin Med Phys 2022; 23:e13572. [PMID: 35213089 PMCID: PMC9121035 DOI: 10.1002/acm2.13572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 02/06/2022] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
Head and neck cancers present challenges in radiation treatment planning due to the large number of critical structures near the target(s) and highly heterogeneous tissue composition. While Monte Carlo (MC) dose calculations currently offer the most accurate approximation of dose deposition in tissue, the switch to MC presents challenges in preserving the parameters of care. The differences in dose‐to‐tissue were widely discussed in the literature, but mostly in the context of recalculating the existing plans rather than reoptimizing with the MC dose engine. Also, the target dose homogeneity received less attention. We adhere to strict dose homogeneity objectives in clinical practice. In this study, we started with 21 clinical volumetric‐modulated arc therapy (VMAT) plans previously developed in Pinnacle treatment planning system. Those plans were recalculated “as is” with RayStation (RS) MC algorithm and then reoptimized in RS with both collapsed cone (CC) and MC algorithms. MC statistical uncertainty (0.3%) was selected carefully to balance the dose computation time (1–2 min) with the planning target volume (PTV) dose‐volume histogram (DVH) shape approaching that of a “noise‐free” calculation. When the hot spot in head and neck MC‐based treatment planning is defined as dose to 0.03 cc, it is exceedingly difficult to limit it to 105% of the prescription dose, as we were used to with the CC algorithm. The average hot spot after optimization and calculation with RS MC was statistically significantly higher compared to Pinnacle and RS CC algorithms by 1.2 and 1.0 %, respectively. The 95% confidence interval (CI) observed in this study suggests that in most cases a hot spot of ≤107% is achievable. Compared to the 95% CI for the previous clinical plans recalculated with RS MC “as is” (upper limit 108%), in real terms this result is at least as good or better than the historic plans.
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Affiliation(s)
- Vladimir Feygelman
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
| | - Kujtim Latifi
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
| | - Mark Bowers
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
| | - Kevin Greco
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
| | - Eduardo G Moros
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
| | - Max Isacson
- RaySearch Laboratories AB, Stockholm, Sweden
| | | | - Jimmy Caudell
- Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, USA
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Jurado-Bruggeman D, Muñoz-Montplet C, Hernandez V, Saez J, Fuentes-Raspall R. Impact of the dose quantity used in MV photon optimization on dose distribution, robustness, and complexity. Med Phys 2021; 49:648-665. [PMID: 34855988 DOI: 10.1002/mp.15389] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 10/09/2021] [Accepted: 11/18/2021] [Indexed: 11/09/2022] Open
Abstract
PURPOSE Convolution/superposition algorithms used in megavoltage (MV) photon radiotherapy model radiation transport in water, yielding dose to water-in-water (Dw,w ). Advanced algorithms constitute a step forward, but their dose distributions in terms of dose to medium-in-medium (Dm,m ) or dose to water-in-medium (Dw,m ) can be problematic when used in plan optimization due to their different dose responses to some atomic composition heterogeneities. Failure to take this into account can lead to undesired overcorrections and thus to unnoticed suboptimal and unrobust plans. Dose to reference-like medium (Dref,m* ) was recently introduced to overcome these limitations while ensuring accurate transport. This work evaluates and compares the performance of these four dose quantities in planning target volume (PTV)-based optimization. METHODS We considered three cases with heterogeneities inside the PTV: virtual phantom with water surrounded by bone; head and neck; and lung. These cases were planned with volumetric modulated arc therapy (VMAT) technique, optimizing with the same setup and objectives for each dose quantity. We used different algorithms of the Varian Eclipse treatment planning system (TPS): Acuros XB (AXB) for Dm,m and Dw,m , and Analytical Anisotropic Algorithm (AAA) for Dw,w . Dref,m* was obtained from Dm,m distributions using an in-house software considering water as the reference medium (Dw,m* ). The optimization process consisted of: (1) common first optimization, (2) dose distribution computed for each quantity, (3) re-optimization, and (4) final calculation for each dose quantity. The dose distribution, robustness to patient setup errors, and complexity of the plans were analyzed and compared. RESULTS The quantities showed similar dose distributions after the optimization but differed in terms of plan robustness. The cases with soft tissue and high-density heterogeneities followed the same pattern. For AXB Dm,m , cold regions appeared in the heterogeneities after the first optimization. They were compensated in the second optimization through local fluence increases, but any positional mismatch impacted robustness, with clinical target volume (CTV) variations from the nominal scenario around +3% for bone and up to +7% for metal. For AXB Dw,m the pattern was inverse (hot regions compensated by fluence decreases) and more pronounced, with CTV dose variations around -7% for bone and up to -17% for metal. Neither AXB Dw,m* nor AAA Dw,w presented these dose inhomogeneities, which resulted in more robust plans. However, Dw,w differed markedly from the other quantities in the lung case because of its lower radiation transport accuracy. AXB Dm,m was the most complex of the four dose quantities and AXB Dw,m* the least complex, though we observed no major differences in this regard. CONCLUSIONS The dose quantity used in MV photon optimization can affect plan robustness. Dw,w distributions from convolution/superposition algorithms are robust but may not provide sufficient radiation transport accuracy in some cases. Dm,m and Dw,m from advanced algorithms can compromise robustness because their different responses to some composition heterogeneities introduce additional fluence compensations. Dref,m* offers advantages in plan optimization and evaluation, producing accurate and robust plans without increasing complexity. Dref,m* can be easily implemented as a built-in feature of the TPS and can facilitate and simplify the treatment planning process when using advanced algorithms. Final reporting can be kept in Dm,m or Dw,m for clinical correlations.
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Affiliation(s)
- Diego Jurado-Bruggeman
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Girona, Spain
| | - Carles Muñoz-Montplet
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Girona, Spain.,Department of Medical Sciences, University of Girona, Girona, Spain
| | - Victor Hernandez
- Department of Medical Physics, Hospital Universitari Sant Joan de Reus, IISPV, Tarragona, Spain.,Universitat Rovira i Virgili, Tarragona, Spain
| | - Jordi Saez
- Department of Radiation Oncology, Hospital Clínic de Barcelona, Barcelona, Spain
| | - Rafael Fuentes-Raspall
- Department of Medical Sciences, University of Girona, Girona, Spain.,Radiation Oncology Department, Institut Català d'Oncologia, Girona, Spain
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8
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Hardcastle N, Hughes J, Siva S, Kron T. Dose calculation and reporting with a linear Boltzman transport equation solver in vertebral SABR. Phys Eng Sci Med 2021; 45:43-48. [PMID: 34813052 DOI: 10.1007/s13246-021-01076-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 11/05/2021] [Indexed: 11/29/2022]
Abstract
Vertebral Stereotactic ablative body radiotherapy (SABR) involves substantial tumour density heterogeneities. We evaluated the impact of a linear Boltzmann transport equation (LBTE) solver dose calculation on vertebral SABR dose distributions. A sequential cohort of 20 patients with vertebral metastases treated with SABR were selected. Treatment plans were initially planned with a convolution style dose calculation algorithm. The plan was copied and recalculated with a LBTE algorithm reporting both dose to water (Dw) or dose to medium (Dm). Target dose as a function of CT number, and spinal cord dose was compared between algorithms. Compared with a convolution algorithm, there was minimal change in PTV D90% with LBTE. LBTE reporting Dm resulted in reduced GTV D50% by (mean, 95% CI) 2.2% (1.9-2.6%) and reduced Spinal Cord PRV near-maximum dose by 3.0% (2.0-4.1%). LBTE reporting Dw resulted in increased GTV D50% by 2.4% (1.8-3.0%). GTV D50% decreased or increased with increasing CT number with Dm or Dw respectively. LBTE, reporting either Dm or Dw resulted in decreased central spinal cord dose by 8.7% (7.1-10.2%) and 7.2% (5.7-8.8%) respectively. Reported vertebral SABR tumour dose when calculating with an LBTE algorithm depends on tumour density. Spinal cord near-maximum dose was lower when using LBTE algorithm reporting Dm, which may result in higher spinal cord doses being delivered than with a convolution style algorithm. Spinal cord central dose was significantly lower with LBTE, potentially reflecting LBTE transport approximations.
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Affiliation(s)
- Nicholas Hardcastle
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC, 3012, Australia. .,Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia. .,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia.
| | - Jeremy Hughes
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC, 3012, Australia
| | - Shankar Siva
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC, 3012, Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia
| | - Tomas Kron
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, VIC, 3012, Australia.,Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, Australia.,Centre for Medical Radiation Physics, University of Wollongong, Wollongong, Australia
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Sanchez-Parcerisa D, Sanz-García I, Ibáñez P, España S, Espinosa A, Gutiérrez-Neira C, López A, Vera JA, Mazal A, Fraile LM, Udías JM. Radiochromic film dosimetry for protons up to 10 MeV with EBT2, EBT3 and unlaminated EBT3 films. Phys Med Biol 2021; 66. [PMID: 33910190 DOI: 10.1088/1361-6560/abfc8d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 04/28/2021] [Indexed: 11/12/2022]
Abstract
Passive dosimetry with radiochromic films is widely used in proton radiotherapy, both in clinical and scientific environments, thanks to its simplicity, high spatial resolution and dose-rate independence. However, film under-response for low-energy protons, the so-called linear-energy transfer (LET) quenching, must be accounted and corrected for. We perform a meta-analysis on existing film under-response data with EBT, EBT2 and EBT3 GAFchromic™ films and provide a common framework to integrate it, based on the calculation of dose-averaged LET in the active layer of the films. We also report on direct measurements with the 10 MeV proton beam at the Center for Microanalysis of Materials (CMAM) for EBT2, EBT3 and unlaminated EBT3 films, focusing on the 20-80 keVμm-1LET range, where previous data was scarce. Measured film relative efficiency (RE) values are in agreement with previously reported data from the literature. A model on film RE constructed with combined literature and own experimental values in the 5-80 keVμm-1LET range is presented, supporting the hypothesis of a linear decrease of RE with LET, with no remarkable differences between the three types of films analyzed.
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Affiliation(s)
- Daniel Sanchez-Parcerisa
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Sedecal Molecular Imaging, Algete, Madrid, Spain
| | - Irene Sanz-García
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain
| | - Paula Ibáñez
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Samuel España
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain.,Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Andrea Espinosa
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - Carolina Gutiérrez-Neira
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Centro de Microanálisis de Materiales (CMAM), Universidad Autónoma de Madrid, Spain.,ALBA Synchrotron Light Source (CELLS-ALBA), Cerdanyola del Vallès, Barcelona, Spain
| | - Alfonso López
- Dept. de Radiofísica y Protección Radiológica, Hospital de Fuenlabrada, Madrid, Spain
| | - Juan Antonio Vera
- Centro de Protonterapia de Quirónsalud, Pozuelo de Alarcón, Madrid, Spain
| | - Alejandro Mazal
- Centro de Protonterapia de Quirónsalud, Pozuelo de Alarcón, Madrid, Spain
| | - Luis Mario Fraile
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
| | - José Manuel Udías
- Grupo de Física Nuclear, EMFTEL and IPARCOS, Universidad Complutense de Madrid, CEI Moncloa, Madrid, Spain.,Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), Madrid, Spain
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Muñoz-Montplet C, Fuentes-Raspall R, Jurado-Bruggeman D, Agramunt-Chaler S, Onsès-Segarra A, Buxó M. Dosimetric Impact of Acuros XB Dose-to-Water and Dose-to-Medium Reporting Modes on Lung Stereotactic Body Radiation Therapy and Its Dependency on Structure Composition. Adv Radiat Oncol 2021; 6:100722. [PMID: 34258473 PMCID: PMC8256186 DOI: 10.1016/j.adro.2021.100722] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/22/2021] [Accepted: 05/07/2021] [Indexed: 11/28/2022] Open
Abstract
Purpose Our purpose was to assess the dosimetric effect of switching from the analytical anisotropic algorithm (AAA) to Acuros XB (AXB), with dose-to-medium (Dm) and dose-to-water (Dw) reporting modes, in lung stereotactic body radiation therapy patients and determine whether planning-target-volume (PTV) dose prescriptions and organ-at-risk constraints should be modified under these circumstances. Methods and Materials We included 54 lung stereotactic body radiation therapy patients. We delineated the PTV, the ipsilateral lung, the contralateral lung, the heart, the spinal cord, the esophagus, the trachea, proximal bronchi, the ribs, and the great vessels. We performed dose calculations with AAA and AXB, then compared clinically relevant dose-volume parameters. Paired t tests were used to analyze differences of means. We propose a method, based on the composition of the involved structures, for predicting differences between AXB Dw and Dm calculations. Results The largest difference between the algorithms was 4%. Mean dose differences between AXB Dm and AXB Dw depended on the average composition of the volumes. Compared with AXB, AAA underestimated all PTV dose-volume parameters (-0.7 Gy to -0.1 Gy) except for gradient index, which was significantly higher (4%). It also underestimated V5 of the contralateral lung (-0.3%). Significant differences in near-maximum doses (D2) to the ribs were observed between AXB Dm and AAA (1.7%) and between AXB Dw and AAA (-1.6%). AAA-calculated D2 was slightly higher in the remaining organs at risk. Conclusions Differences between AXB and AAA are below the threshold of clinical detectability (5%) for most patients. For a small subgroup, the difference in maximum doses to the ribs between AXB Dw and AXB Dm may be clinically significant. The differences in dose volume parameters between AXB Dw and AXB Dm can be predicted with reference to structure composition.
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Affiliation(s)
- Carles Muñoz-Montplet
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Avda. França s/n, 17007 Girona, Spain.,Department of Medical Sciences, University of Girona, C/Emili Grahit 77, 17003 Girona, Spain
| | - Rafael Fuentes-Raspall
- Department of Medical Sciences, University of Girona, C/Emili Grahit 77, 17003 Girona, Spain.,Radiation Oncology Department, Institut Català d'Oncologia, Avda. França s/n, 17007 Girona, Spain
| | - Diego Jurado-Bruggeman
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Avda. França s/n, 17007 Girona, Spain
| | - Sebastià Agramunt-Chaler
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Avda. França s/n, 17007 Girona, Spain
| | - Albert Onsès-Segarra
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Avda. França s/n, 17007 Girona, Spain
| | - Maria Buxó
- Girona Biomedical Research Institute (IDIBGI), Parc Hospitalari Martí i Julià, Edifici M2, 17190, Salt, Spain
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Dumas JL, Dal R, Zefkili S, Robilliard M, Losa S, Birba I, Vu-Bezin J, Beddok A, Calugaru V, Dutertre G, De Marzi L. Addressing the dosimetric impact of bone cement and vertebroplasty in stereotactic body radiation therapy. Phys Med 2021; 85:42-49. [PMID: 33965740 DOI: 10.1016/j.ejmp.2021.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 04/08/2021] [Accepted: 04/23/2021] [Indexed: 10/21/2022] Open
Abstract
PURPOSE Bone cement used for vertebroplasty can affect the accuracy on the dose calculation of the radiation therapy treatment. In addition the CT values of high density objects themselves can be misrepresented in kVCT images. The aim of our study is then to propose a streamlined approach for estimating the real density of cement implants used in stereotactic body radiation therapy. METHODS Several samples of cement were manufactured and irradiated in order to investigate the impact of their composition on the radiation dose. The validity of the CT conversion method for a range of photon energies was investigated, for the studied samples and on six patients. Calculations and measurements were carried out with various overridden densities and dose prediction algorithms (AXB with dose-to-medium reporting or AAA) in order to find the effective density override. RESULTS Relative dose differences of several percent were found between the dose measured and calculated downstream of the implant using an ion chamber and TPS or EPID dosimetry. If the correct density is assigned to the implant, calculations can provide clinically acceptable accuracy (gamma criteria of 3%/2 mm). The use of MV imaging significantly favors the attribution of a correct equivalent density to the implants compared to the use of kVCT images. CONCLUSION The porosity and relative density of the various studied implants vary significantly. Bone cement density estimations can be characterized using MV imaging or planar in vivo dosimetry, which could help determining whether errors in dose calculations are due to incorrect densities.
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Affiliation(s)
- Jean-Luc Dumas
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France.
| | - Romaric Dal
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Sofia Zefkili
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Magalie Robilliard
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Sandra Losa
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Imène Birba
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Jérémi Vu-Bezin
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Arnaud Beddok
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | - Valentin Calugaru
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France
| | | | - Ludovic De Marzi
- Institut Curie, PSL Research University, Radiation Oncology Department, Paris, France; Institut Curie, University Paris Saclay, PSL Research University, Inserm LITO, Orsay, France.
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Shaw M, Lye J, Alves A, Hanlon M, Lehmann J, Supple J, Porumb C, Williams I, Geso M, Brown R. Measuring the dose in bone for spine stereotactic body radiotherapy. Phys Med 2021; 84:265-273. [PMID: 33773909 DOI: 10.1016/j.ejmp.2021.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 02/08/2021] [Accepted: 03/05/2021] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Current quality assurance of radiotherapy involving bony regions generally utilises homogeneous phantoms and dose calculations, ignoring the challenges of heterogeneities with dosimetry problems likely occurring around bone. Anthropomorphic phantoms with synthetic bony materials enable realistic end-to-end testing in clinical scenarios. This work reports on measurements and calculated corrections required to directly report dose in bony materials in the context of comprehensive end-to-end dosimetry audit measurements (63 plans, 6 planning systems). MATERIALS AND METHODS Radiochromic film and microDiamond measurements were performed in an anthropomorphic spine phantom containing bone equivalent materials. Medium dependent correction factors, kmed, were established using 6 MV and 10 MV Linear Accelerator Monte Carlo simulations to account for the detectors being calibrated in water, but measuring in regions of bony material. Both cortical and trabecular bony material were investigated for verification of dose calculations in dose-to-medium (Dm,m) and dose-to-water (Dw,w) scenarios. RESULTS For Dm,m calculations, modelled correction factors for cortical and trabecular bone in film measurements, and for trabecular bone in microDiamond measurements were 0.875(±0.1%), 0.953(±0.3%) and 0.962(±0.4%), respectively. For Dw,w calculations, the corrections were 0.920(±0.1%), 0.982(±0.3%) and 0.993(±0.4%), respectively. In the audit, application of the correction factors improves the mean agreement between treatment plans and measured microDiamond dose from -2.4%(±3.9%) to 0.4%(±3.7%). CONCLUSION Monte Carlo simulations provide a method for correcting the dose measured in bony materials allowing more accurate comparison with treatment planning system doses. In verification measurements, algorithm specific correction factors should be applied to account for variations in bony material for calculations based on Dm,m and Dw,w.
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Affiliation(s)
- Maddison Shaw
- Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia; School of Health and Biomedical Sciences, RMIT University, Melbourne, Australia.
| | - Jessica Lye
- Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia; Olivia Newton John Cancer Wellness Centre, Melbourne, Australia
| | - Andrew Alves
- Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia
| | - Maximilian Hanlon
- Primary Standards Dosimetry Laboratory, ARPANSA, Melbourne, Australia
| | - Joerg Lehmann
- Department of Radiation Oncology, Calvary Mater Newcastle, Newcastle, Australia; School of Science, RMIT University, Melbourne, Australia; School of Mathematical and Physical Sciences, University of Newcastle, Australia; Institute of Medical Physics, University of Sydney, Australia
| | - Jeremy Supple
- Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia
| | - Claudiu Porumb
- Alfred Health Radiation Oncology, The Alfred Hospital, Melbourne, Australia
| | - Ivan Williams
- Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia
| | - Moshi Geso
- School of Health and Biomedical Sciences, RMIT University, Melbourne, Australia
| | - Rhonda Brown
- Australian Clinical Dosimetry Service, Australian Radiation Protection and Nuclear Safety Agency, Melbourne, Australia
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Report dose-to-medium in clinical trials where available; a consensus from the Global Harmonisation Group to maximize consistency. Radiother Oncol 2021; 159:106-111. [PMID: 33741471 DOI: 10.1016/j.radonc.2021.03.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 03/05/2021] [Accepted: 03/06/2021] [Indexed: 11/22/2022]
Abstract
PURPOSE To promote consistency in clinical trials by recommending a uniform framework as it relates to radiation transport and dose calculation in water versus in medium. METHODS The Global Quality Assurance of Radiation Therapy Clinical Trials Harmonisation Group (GHG; www.rtqaharmonization.org) compared the differences between dose to water in water (Dw,w), dose to water in medium (Dw,m), and dose to medium in medium (Dm,m). This was done based on a review of historical frameworks, existing literature and standards, clinical issues in the context of clinical trials, and the trajectory of radiation dose calculations. Based on these factors, recommendations were developed. RESULTS No framework was found to be ideal or perfect given the history, complexity, and current status of radiation therapy. Nevertheless, based on the evidence available, the GHG established a recommendation preferring dose to medium in medium (Dm,m). CONCLUSIONS Dose to medium in medium (Dm,m) is the preferred dose calculation and reporting framework. If an institution's planning system can only calculate dose to water in water (Dw,w), this is acceptable.
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Martin-Martin G, Walter S, Guibelalde E. Dose accuracy improvement on head and neck VMAT treatments by using the Acuros algorithm and accurate FFF beam calibration. ACTA ACUST UNITED AC 2021; 26:73-85. [PMID: 33948305 DOI: 10.5603/rpor.a2021.0014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/22/2020] [Indexed: 11/25/2022]
Abstract
Background The purpose of this study was to assess dose accuracy improvement and dosimetric impact of switching from the anisotropic analytical algorithm (AA) to the Acuros XB algorithm (AXB) when performing an accurate beam calibration in head and neck (H&N) FFF-VMAT treatments. Materials and methods Twenty H&N cancer patients treated with FFF-VMAT techniques were included. Calculations were performed with the AA and AXB algorithm (dose-to-water - AXBw- and dose-to-medium - AXBm-). An accurate beam calibration was used for AXB calculations. Dose prescription to the tumour (PTV70) and at-risk-nodal region (PTV58.1) were 70 Gy and 58.1 Gy, respectively. A PTV70_bone including bony structures in PTV70 was contoured. Dose-volume parameters were compared between the algorithms. Statistical tests were used to analyze the differences in mean values and the correlation between compliance with the D95 > 95% requirement and occurrence of local recurrence. Results AA systematically overestimated the dose compared to AXB algorithm with mean dose differences within 1.3 Gy/2%, except for the PTV70_bone (2.2 Gy/3.2%). Dose differences were significantly higher for AXBm calculations when including accurate beam calibration (maximum dose differences up to 2.8 Gy/4.1% and 4.2 Gy/6.3% for PTV70 and PTV70_bone, respectively). 80% of AA-calculated plans did not meet the D95 > 95% requirement after recalculation with AXBm and accurate beam calibration. The reduction in D95 coverage in the tumour was not clinically relevant. Conclusions Using the AXBm algorithm and carefully reviewing the beam calibration procedure in H&N FFF-VMAT treatments ensures (1) dose accuracy increase by approximately 3%; (2) a consequent dose increase in targets; and (3) a dose reporting mode that is consistent with the trend of current algorithms.
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Affiliation(s)
- Guadalupe Martin-Martin
- Medical Physics and Radiation Protection Service, Hospital Universitario de Fuenlabrada, Madrid, Spain
| | - Stefan Walter
- Department of Medicine and Public Health, Rey Juan Carlos University, Alcorcón, Spain
| | - Eduardo Guibelalde
- Medical Physics Group, Department of Radiology, University Complutense of Madrid, Madrid, Spain
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Younes T, Chauvin M, Delbaere A, Labour J, Fonteny V, Simon L, Fares G, Vieillevigne L. Towards the standardization of the absorbed dose report mode in high energy photon beams. Phys Med Biol 2021; 66:045009. [PMID: 33296874 DOI: 10.1088/1361-6560/abd22c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The benefits of using an algorithm that reports absorbed dose-to-medium have been jeopardized by the clinical experience and the experimental protocols that have mainly relied on absorbed dose-to-water. The aim of the present work was to investigate the physical aspects that govern the dosimetry in heterogeneous media using Monte Carlo method and to introduce a formalism for the experimental validation of absorbed dose-to-medium reporting algorithms. Particle fluence spectra computed within the sensitive volume of two simulated detectors (T31016 Pinpoint 3D ionization chamber and EBT3 radiochromic film) placed in different media (water, RW3, lung and bone) were compared to those in the undisturbed media for 6 MV photon beams. A heterogeneity correction factor that takes into account the difference between the detector perturbation in medium and under reference conditions as well as the stopping-power ratios was then derived for all media using cema calculations. Furthermore, the different conversion approaches and Eclipse treatment planning system algorithms were compared against the Monte Carlo absorbed dose reports. The detectors electron fluence perturbation in RW3 and lung media were close to that in water (≤1.5%). However, the perturbation was greater in bone (∼4%) and impacted the spectral shape. It was emphasized that detectors readings should be corrected by the heterogeneity correction factor that ranged from 0.932 in bone to 0.985 in lung. Significant discrepancies were observed between all the absorbed dose reports and conversions, especially in bone (exceeding 10%) and to a lesser extent in RW3. Given the ongoing advances in dose calculation algorithms, it is essential to standardize the absorbed dose report mode with absorbed dose-to-medium as a favoured choice. It was concluded that a retrospective conversion should be avoided and switching from absorbed dose-to-water to absorbed dose-to-medium reporting algorithm should be carried out by a direct comparison of both algorithms.
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Affiliation(s)
- Tony Younes
- Department of Medical Physics, Institut Claudius Regaud-Institut Universitaire du Cancer de Toulouse Oncopole, 1 avenue Irène Joliot Curie, F-31059 Toulouse Cedex 9, France. Centre de Recherche et de Cancérologie de Toulouse, UMR1037 INSERM-Université Toulouse 3-ERL5294 CNRS, 2 avenue Hubert Curien, F-31037 Toulouse Cedex 1, France. Laboratoire de 'Mathématiques et Applications', Unité de recherche 'Mathématiques et Modélisation', Centre d'analyses et de recherche, Faculté des sciences, Université Saint-Joseph, Beyrouth 1104 2020, Lebanon
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Kolacio MŠ, Brkić H, Faj D, Radojčić ĐS, Rajlić D, Obajdin N, Jurković S. Validation of two calculation options built in Elekta Monaco Monte Carlo based algorithm using MCNP code. Radiat Phys Chem Oxf Engl 1993 2021. [DOI: 10.1016/j.radphyschem.2020.109237] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Jurado-Bruggeman D, Muñoz-Montplet C, Vilanova JC. A new dose quantity for evaluation and optimisation of MV photon dose distributions when using advanced algorithms: proof of concept and potential applications. Phys Med Biol 2020; 65:235020. [PMID: 32906107 DOI: 10.1088/1361-6560/abb6bc] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Advanced algorithms used in MV photon radiotherapy model radiation transport in any media. They represent a step forward but introduce new uncertainties and questions, including whether to report the doses to water (Dw,m) or medium (Dm,m) voxels, and the impact of fluence changes introduced by surrounding media. These aspects can compromise consistency between both reporting modes and with previous algorithms in which clinical experience is based. This study introduces a new dose quantity, the dose-to-reference-like medium, to overcome the aforementioned shortcomings. It is linked to a reference medium, water in this study (Dw,m*), and defined as the absorbed dose in a voxel of this reference medium surrounded by a reference-like medium with the same radiation transport characteristics as the original one. We propose to derive Dw,m* distributions by post-processing Dw,m or Dm,m applying a correction factor (CF) to each voxel which depends on its composition. We present and justify a simple and straightforward method to obtain CFs that only involves two phantoms with the same density: one with the considered composition and the other with that of the reference medium. A proof of concept was performed in a clinical environment for Acuros XB (AXB) advanced algorithm and 6 MV photon beams. The CFs were derived for the tissues characterised in Acuros. Dw,m* was compared to Dw,m, Dm,m, and Dw,w from AAA analytical algorithm for some virtual and clinical cases. All the previous quantities presented limitations that can be solved by Dw,m*. This new quantity allows the applicability of evaluation parameters, traceability to clinical experience, and isolation of heterogeneity effects to identify optimum plans, offering useful characteristics for plan evaluation and optimisation in clinical practice. Additionally, it also has potential applications in automated treatment planning and multi-centre activities such as clinical trials, audits, benchmarking, and shared models for automation.
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Affiliation(s)
- Diego Jurado-Bruggeman
- Medical Physics and Radiation Protection Department, Institut Català d'Oncologia, Girona, Spain
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Dosimetric impact of switching from AAA to Acuros dose-to-water and dose-to-medium for RapidArc plans of nasopharyngeal carcinomas. Cancer Radiother 2020; 24:842-850. [PMID: 33153875 DOI: 10.1016/j.canrad.2020.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/12/2020] [Accepted: 05/16/2020] [Indexed: 11/22/2022]
Abstract
PURPOSE This work aims to evaluate the dosimetric consequences of replacing the Anisotropic Analytical Algorithm (AAA) by Acuros XB (AXB), dose-to-water (Dw) or dose-to-medium (Dm), for RapidArc plans of nasopharyngeal carcinomas (NPC). MATERIALS AND METHODS Seventeen NPC plans created with AAA (v15.6) were recalculated with AXB (v15.6) Dw and Dm. The dose-volume parameters to the planning target volumes (PTV) and relevant organs at risk (OAR) were compared. The high dose PTV was divided into bone, air and tissue components and the comparison was performed for each of them. RESULTS AXB Dw revealed no significant differences in the PTVs compared to AAA. Lower values were observed to spinal cord, brainstem, oral cavity and parotids (0.5% to 2.3%), and higher values to cochleas (up to 5.4%) and mandible (up to 6.7%). AXB Dm predicted lower values than AAA for all PTVs and OARs (2.0% to 6.1%). For the bone PTV subvolume, AXB Dw and Dm predicted respectively higher (2.4%) and lower (2.2% to 3.4%) values. No significant differences were noted in air. AXB predicted lower values than AAA in soft tissues (0.4% to 1.6%). The largest difference was found to the mandible V60Gy parameter, with median differences of 6.7% for AXB Dw and -6.0% for AXB Dm. CONCLUSION Significant dose differences are expected when switching from AAA to AXB in NPC cases. The dose prescriptions and the tolerance limits for some OARs, especially those of high density, may need to be adjusted depending on the selected dose calculation algorithm and reporting mode.
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Radojcic DS, Casar B, Rajlic D, Kolacio MS, Mendez I, Obajdin N, Debeljuh DD, Jurkovic S. Experimental validation of Monte Carlo based treatment planning system in bone density equivalent media. Radiol Oncol 2020; 54:495-504. [PMID: 32936784 PMCID: PMC7585341 DOI: 10.2478/raon-2020-0051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/09/2020] [Indexed: 11/20/2022] Open
Abstract
Introduction Advanced, Monte Carlo (MC) based dose calculation algorithms, determine absorbed dose as dose to medium-in-medium (Dm,m) or dose to water-in-medium (Dw,m). Some earlier studies identified the differences in the absorbed doses related to the calculation mode, especially in the bone density equivalent (BDE) media. Since the calculation algorithms built in the treatment planning systems (TPS) should be dosimetrically verified before their use, we analyzed dose differences between two calculation modes for the Elekta Monaco TPS. We compared them with experimentally determined values, aiming to define a supplement to the existing TPS verification methodology. Materials and methods In our study, we used a 6 MV photon beam from a linear accelerator. To evaluate the accuracy of the TPS calculation approaches, measurements with a Farmer type chamber in a semi-anthropomorphic phantom were compared to those obtained by two calculation options. The comparison was made for three parts of the phantom having different densities, with a focus on the BDE part. Results Measured and calculated doses were in agreement for water and lung equivalent density materials, regardless of the calculation mode. However, in the BDE part of the phantom, mean dose differences between the calculation options ranged from 5.7 to 8.3%, depending on the method used. In the BDE part of the phantom, neither of the two calculation options were consistent with experimentally determined absorbed doses. Conclusions Based on our findings, we proposed a supplement to the current methodology for the verification of commercial MC based TPS by performing additional measurements in BDE material.
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Affiliation(s)
- Djeni Smilovic Radojcic
- Medical Physics Department, University Hospital Rijeka, Rijeka, Croatia
- Department of Medical Physics and Biophysics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Bozidar Casar
- Department for Dosimetry and Quality of Radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
| | - David Rajlic
- Medical Physics Department, University Hospital Rijeka, Rijeka, Croatia
| | | | - Ignasi Mendez
- Department for Dosimetry and Quality of Radiological procedures, Institute of Oncology Ljubljana, Ljubljana, Slovenia
| | - Nevena Obajdin
- Medical Physics Department, University Hospital Rijeka, Rijeka, Croatia
| | - Dea Dundara Debeljuh
- Medical Physics Department, University Hospital Rijeka, Rijeka, Croatia
- General Hospital Pula, Radiology Department, Pula, Croatia
| | - Slaven Jurkovic
- Medical Physics Department, University Hospital Rijeka, Rijeka, Croatia
- Department of Medical Physics and Biophysics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
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Kumar S, Nahum AE, Chetty IJ. Monte-Carlo-computed dose, kerma and fluence distributions in heterogeneous slab geometries irradiated by small megavoltage photon fields. ACTA ACUST UNITED AC 2020; 65:175012. [DOI: 10.1088/1361-6560/ab98d1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Dubus F, Talbot A, Maurice JB, Devos L, Reyns N, Vermandel M. Evaluation and validation of the convolution algorithm for Leksell Gamma knife radiosurgery. ACTA ACUST UNITED AC 2020; 65:155012. [DOI: 10.1088/1361-6560/ab91da] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Heng VJ, Renaud MA, Zerouali K, Doucet R, Diamant A, Bahig H, DeBlois F, Seuntjens J. Large-scale dosimetric assessment of Monte Carlo recalculated doses for lung robotic stereotactic body radiation therapy. Phys Med 2020; 76:7-15. [PMID: 32569954 DOI: 10.1016/j.ejmp.2020.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 04/11/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022] Open
Abstract
Owing to its short computation time and simplicity, the Ray-Tracing algorithm (RAT) has long been used to calculate dose distributions for the CyberKnife system. However, it is known that RAT fails to fully account for tissue heterogeneity and is therefore inaccurate in the lung. The aim of this study is to make a dosimetric assessment of 219 non-small cell lung cancer CyberKnife plans by recalculating their dose distributions using an independent Monte Carlo (MC) method. For plans initially calculated by RAT without heterogeneity corrections, target coverage was found to be significantly compromised when considering MC doses. Only 35.4% of plans were found to comply to their prescription doses. If the normal tissue dose limits were respected in the treatment planning dose, the MC recalculated dose did not exceed these limits in over 97% of the plans. Comparison of RAT and recalculated-MC doses confirmed the overestimation of RAT doses observed in previous studies. An inverse correlation between the RAT/MC dose ratio and the target size was also found to be statistically significant (p<10-4), consistent with other studies. In addition, the inaccuracy and variability in target coverage incurred from dose calculations using RAT without heterogeneity corrections was demonstrated. On average, no clinically relevant differences were observed between MC-calculated dose-to-water and dose-to-medium for all tissues investigated (⩽1%). Patients receiving a dose D95% larger than 119 Gy in EQD210 (or ≈52 Gy in 3 fractions) as recalculated by MC were observed to have significantly superior loco-regional progression-free survival rates (p=0.02) with a hazard ratio of 3.45 (95%CI: 1.14-10.5).
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Affiliation(s)
- Veng Jean Heng
- Medical Physics Unit, McGill University and Cedars Cancer Center, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada.
| | - Marc-André Renaud
- Medical Physics Unit, McGill University and Cedars Cancer Center, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Karim Zerouali
- Department of Radiation Oncology, Centre Hospitalier de l'Université de Montréal, 1051 Rue Sanguinet, Montréal, QC H2X 3E4, Canada
| | - Robert Doucet
- Department of Radiation Oncology, Centre Hospitalier de l'Université de Montréal, 1051 Rue Sanguinet, Montréal, QC H2X 3E4, Canada
| | - André Diamant
- Medical Physics Unit, McGill University and Cedars Cancer Center, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
| | - Houda Bahig
- Department of Radiation Oncology, Centre Hospitalier de l'Université de Montréal, 1051 Rue Sanguinet, Montréal, QC H2X 3E4, Canada
| | - François DeBlois
- Department of Radiation Oncology, Centre Hospitalier de l'Université de Montréal, 1051 Rue Sanguinet, Montréal, QC H2X 3E4, Canada
| | - Jan Seuntjens
- Medical Physics Unit, McGill University and Cedars Cancer Center, 1001 Boulevard Décarie, Montréal, QC H4A 3J1, Canada
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Improving the accuracy of converting dose to medium to dose to water algorithms in small megavoltage photon fields in dose to medium based treatment planning systems. Phys Med 2020; 71:62-70. [DOI: 10.1016/j.ejmp.2020.01.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 01/17/2020] [Accepted: 01/26/2020] [Indexed: 11/18/2022] Open
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Cabanas ML, Yan C, Lalonde RJ, Heron DE, Huq MS. Which Dose Specification Should Be Used for NRG Radiation Therapy Trials: Dose-to-Medium or Dose-to-Water? Pract Radiat Oncol 2020; 10:e103-e110. [DOI: 10.1016/j.prro.2019.08.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 08/06/2019] [Accepted: 08/25/2019] [Indexed: 10/26/2022]
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25
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Kry SF, Feygelman V, Balter P, Knöös T, Charlie Ma C, Snyder M, Tonner B, Vassiliev ON. AAPM Task Group 329: Reference dose specification for dose calculations: Dose‐to‐water or dose‐to‐muscle? Med Phys 2020; 47:e52-e64. [DOI: 10.1002/mp.13995] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 12/03/2019] [Accepted: 12/19/2019] [Indexed: 11/09/2022] Open
Affiliation(s)
| | | | | | - Tommy Knöös
- Skåne University Hospital and Lund University Malmo Sweden
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Ma CMC, Chetty IJ, Deng J, Faddegon B, Jiang SB, Li J, Seuntjens J, Siebers JV, Traneus E. Beam modeling and beam model commissioning for Monte Carlo dose calculation-based radiation therapy treatment planning: Report of AAPM Task Group 157. Med Phys 2019; 47:e1-e18. [PMID: 31679157 DOI: 10.1002/mp.13898] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 10/01/2019] [Accepted: 10/18/2019] [Indexed: 11/07/2022] Open
Abstract
Dose calculation plays an important role in the accuracy of radiotherapy treatment planning and beam delivery. The Monte Carlo (MC) method is capable of achieving the highest accuracy in radiotherapy dose calculation and has been implemented in many commercial systems for radiotherapy treatment planning. The objective of this task group was to assist clinical physicists with the potentially complex task of acceptance testing and commissioning MC-based treatment planning systems (TPS) for photon and electron beam dose calculations. This report provides an overview on the general approach of clinical implementation and testing of MC-based TPS with a specific focus on models of clinical photon and electron beams. Different types of beam models are described including those that utilize MC simulation of the treatment head and those that rely on analytical methods and measurements. The trade-off between accuracy and efficiency in the various source-modeling approaches is discussed together with guidelines for acceptance testing of MC-based TPS from the clinical standpoint. Specific recommendations are given on methods and practical procedures to commission clinical beam models for MC-based TPS.
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Affiliation(s)
- Chang Ming Charlie Ma
- Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Indrin J Chetty
- Radiation Oncology Department, Henry Ford Health System, Detroit, MI, 48188, USA
| | - Jun Deng
- Department of Therapeutic Radiology, Yale University, New Haven, CT, 06032, USA
| | - Bruce Faddegon
- Department of Radiation Oncology, UCSF, San Francisco, CA, 94143, USA
| | - Steve B Jiang
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | | | - Jan Seuntjens
- Medical Physics Unit, McGill University, Montreal, QC, H4A 3J1, Canada
| | - Jeffrey V Siebers
- Department of Radiation Oncology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Erik Traneus
- RaySearch Laboratories AB, SE-103 65, Stockholm, Sweden
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Delbaere A, Younes T, Vieillevigne L. On the conversion from dose-to-medium to dose-to-water in heterogeneous phantoms with Acuros XB and Monte Carlo calculations. ACTA ACUST UNITED AC 2019; 64:195016. [DOI: 10.1088/1361-6560/ab3df3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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28
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Thi Oanh L, Tai DT, Thi Hong Loan T, Minh TH, Van Minh T, Chow JCL. Dosimetric evaluation of lung treatment plans produced by the Prowess Panther system using Monte Carlo simulation. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/ab367d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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29
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Hardcastle N, Montaseri A, Lydon J, Kron T, Osbourne G, Casswell G, Taylor D, Hall L, McDowell L. Dose to medium in head and neck radiotherapy: Clinical implications for target volume metrics. Phys Imaging Radiat Oncol 2019; 11:92-97. [PMID: 33458286 PMCID: PMC7807679 DOI: 10.1016/j.phro.2019.08.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/21/2019] [Accepted: 08/28/2019] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE In radiotherapy dose calculation, advanced type-B dose calculation algorithms can calculate dose to medium (Dm ), as opposed to Type-B algorithms which compute dose to varying densities of water (Dw ). We investigate the impact of Dm on calculated dose and target coverage metrics in head and neck cancer patients. METHODS AND MATERIALS We reviewed 27 successfully treated (disease free at two-years post-(chemo)radiotherapy) human papillomavirus-associated (HPV) oropharyngeal cancer (ONC) patients treated with IMRT. Doses were calculated with Type-B and Linear Boltzman Transport Equation (LBTE) algorithms in a commercial treatment planning system, with the treated multi-leaf collimator patterns and monitor units. Coverage for primary Gross Tumour Volume (GTVp), high dose Planning Target Volume (PTV) (PTV_High), mandible within PTV_High (Mand ∩ PTV) and PTV_High excluding bone (PTV-bone) were compared between the algorithms. RESULTS Dose to 95% of PTV_High with LBTE was on average 1.1 Gy/1.7% lower than with Type-B (95%CI 1.5-1.9%, p < 0.0001). This magnitude was inversely linearly correlated with the relative volume of the PTV_High containing bone (pearson r = -0.81). Dose to 98% of the GTVp was 0.9 Gy/1.3% lower with LBTE compared with Type-B (95%CI 1.1-1.5%, p < 0.05). Dose to 98% of Mand ∩ PTV was on average 3.4 Gy/5.0% lower with LBTE than with Type-B (95%CI 4.6-5.4%, p < 0.0001). CONCLUSION In OPC treated with IMRT, Dm results in significant reductions in dose to bone in high dose PTVs. Reported GTVp dose was reduced, but by a lower magnitude. Reduced coverage metrics should be expected for OPC patients treated with IMRT, with dose reductions limited to regions of bone.
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Affiliation(s)
- Nicholas Hardcastle
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
- Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522, Australia
| | - Atousa Montaseri
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - Jenny Lydon
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - Tomas Kron
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria, Australia
| | - Glen Osbourne
- Department of Radiation Therapy, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - Georgina Casswell
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - David Taylor
- Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - Lisa Hall
- Department of Radiation Therapy, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
| | - Lachlan McDowell
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Victoria, Australia
- Department of Radiation Oncology, Peter MacCallum Cancer Centre, 305 Grattan St, Melbourne, Victoria 3000, Australia
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