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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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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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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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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: 8] [Impact Index Per Article: 2.7] [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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Hardcastle N, Kron T, Cook O, Lehmann J, Mitchell PLR, Siva S. Credentialing of vertebral stereotactic ablative body radiotherapy in a multi-centre trial. Phys Med 2020; 72:16-21. [PMID: 32193090 DOI: 10.1016/j.ejmp.2020.03.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Revised: 02/11/2020] [Accepted: 03/02/2020] [Indexed: 12/23/2022] Open
Abstract
PURPOSE/OBJECTIVE Stereotactic ablative body radiotherapy (SABR) in multi-centre trials requires rigorous quality assurance to ensure safe and consistent treatment for all trial participants. We report results of vertebral SABR dosimetry credentialing for the ALTG/TROG NIVORAD trial. MATERIAL/METHODS Centres with a previous SABR site visit performed axial film measurement of the benchmarking vertebral plan in a local phantom and submitted radiochromic film images for analysis. Remaining centres had on-site review of SABR processes and axial film measurement of the vertebral benchmarking plan. Films were analysed for dosimetric and positional accuracy: gamma analysis (>90% passing 2%/2mm/10% threshold) and ≤ 1 mm positional accuracy at target-cord interface was required. RESULTS 19 centres were credentialed; 11 had on-site measurement. Delivery devices included linear accelerator, TomoTherapy and CyberKnife systems. Five centres did not achieve 90% gamma passing rate. Of these, three were out of tolerance (OOT) in low (<5Gy) dose regions and > 80% passing rate and deemed acceptable. Two were OOT over the full dose range: one elected not to remeasure; the other also had positional discrepancy greater than 1 mm and repeat measurement with a new plan was in tolerance. The original OOT was attributed to inappropriate MLC constraints. All centres delivered planned target-cord dose gradient within 1 mm. CONCLUSION Credentialing measurements for vertebral SABR in a multi-centre trial showed although the majority of centres delivered accurate vertebral SABR, there is high value in independent audit measurements. One centre with inappropriate MLC settings was detected, which may have resulted in delivery of clinically unacceptable vertebral SABR plans.
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Affiliation(s)
- Nicholas Hardcastle
- Physical Sciences, Peter MacCallum Cancer Centre, VIC, Australia; Centre for Medical Radiation Physics, University of Wollongong, NSW, Australia.
| | - Tomas Kron
- Physical Sciences, Peter MacCallum Cancer Centre, VIC, Australia; Centre for Medical Radiation Physics, University of Wollongong, NSW, Australia; Sir Peter MacCallum Cancer Centre, University of Melbourne, VIC, Australia
| | - Olivia Cook
- Trans Tasman Radiation Oncology Group, NSW, Australia
| | - Joerg Lehmann
- Trans Tasman Radiation Oncology Group, NSW, Australia; School of Mathematical and Physical Sciences, The University of Newcastle, NSW, Australia; Department of Radiation Oncology, Calvary Mater Newcastle, NSW, Australia; Institute of Medical Physics, The University of Sydney, NSW, Australia
| | - Paul L R Mitchell
- Department of Medical Oncology, Olivia Newton John Cancer Centre, Austin Health, VIC, Australia
| | - Shankar Siva
- Radiation Oncology, Peter MacCallum Cancer Centre, VIC, Australia; Sir Peter MacCallum Cancer Centre, University of Melbourne, VIC, Australia
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