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Oliver PAK, Yip E, Tari SY, Wachowicz K, Reynolds M, Burke B, Warkentin B, Fallone BG. Skin dose investigations on a 0.5 T parallel rotating biplanar linac-MR using Monte Carlo simulations and measurements. Med Phys 2024. [PMID: 38873942 DOI: 10.1002/mp.17246] [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: 01/25/2024] [Revised: 05/06/2024] [Accepted: 05/30/2024] [Indexed: 06/15/2024] Open
Abstract
BACKGROUND The Alberta rotating biplanar linac-MR has a 0.5 T magnetic field parallel to the beamline. When developing a new linac-MR system, interactions of charged particles with the magnetic field necessitate careful consideration of skin dose and tissue interface effects. PURPOSE To investigate the effect of the magnetic field on skin dose using measurements and Monte Carlo (MC) simulations. METHODS We develop an MC model of our linac-MR, which we validate by comparison with ion chamber measurements in a water tank. Additionally, MC simulation results are compared with radiochromic film surface dose measurements on solid water. Variations in surface dose as a function of field size are measured using a parallel plate ion chamber in solid water. Using an anthropomorphic computational phantom with a 2 mm-thick skin layer, we investigate dose distributions resulting from three beam arrangements. Magnetic field on and off scenarios are considered for all measurements and simulations. RESULTS For a 20 × 20 cm2 field size,D 0.2 c c ${D_{0.2cc}}$ (the minimum dose to the hottest contiguous 0.2 cc volume) for the top 2 mm of a simple water phantom is 72% when the magnetic field is on, compared to 34% with magnetic field off (values are normalized to the central axis dose maximum). Parallel plate ion chamber measurements demonstrate that the relative increase in surface dose due to the magnetic field decreases with increasing field size. For the anthropomorphic phantom,D ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ (minimum skin dose in the hottest 1 × 1 × 1 cm3 cube) shows relative increases of 20%-28% when the magnetic field is on compared to when it is off. With magnetic field off, skinD ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ is 71%, 56%, and 21% for medial-lateral tangents, anterior-posterior beams, and a five-field arrangement, respectively. For magnetic field on, the corresponding skinD ∼ 0.2 c c ${D_{ \sim 0.2cc}}$ values are 91%, 67%, and 25%. CONCLUSIONS Using a validated MC model of our linac-MR, surface doses are calculated in various scenarios. MC-calculated skin dose varies depending on field sizes, obliquity, and the number of beams. In general, the parallel linac-MR arrangement results in skin dose enhancement due to charged particles spiraling along magnetic field lines, which impedes lateral motion away from the central axis. Nonetheless, considering the results presented herein, treatment plans can be designed to minimize skin dose by, for example, avoiding oblique beams and using a larger number of fields.
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Affiliation(s)
- Patricia A K Oliver
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
- Dept. of Medical Physics, Nova Scotia Health and Dept. of Radiation Oncology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Eugene Yip
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Shima Y Tari
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Keith Wachowicz
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Michael Reynolds
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
| | - Ben Burke
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Brad Warkentin
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
| | - Biagio G Fallone
- Dept. of Medical Physics, Cross Cancer Institute, Edmonton, Alberta, Canada
- Dept. of Oncology, Medical Physics Division, University of Alberta, Edmonton, Alberta, Canada
- MagnetTx Oncology Solutions, Edmonton, Alberta, Canada
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Miéville FA, Pitteloud N, Achard V, Lamanna G, Pisaturo O, Tercier PA, Allal AS. Post-mastectomy radiotherapy: Impact of bolus thickness and irradiation technique on skin dose. Z Med Phys 2023:S0939-3889(23)00041-7. [PMID: 37150728 DOI: 10.1016/j.zemedi.2023.03.004] [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: 01/02/2023] [Revised: 02/27/2023] [Accepted: 03/08/2023] [Indexed: 05/09/2023]
Abstract
PURPOSE To determine 10 MV IMRT and VMAT based protocols with a daily bolus targeting a skin dose of 45 Gy in order to replace the 6 MV tangential fields with a 5 mm thick bolus on alternate days method for post-mastectomy radiotherapy. METHOD We measured the mean surface dose along the chest wall PTV as a function of different bolus thicknesses for sliding window IMRT and VMAT plans. We analyzed surface dose profiles and dose homogeneities and compared them to our standard 6 MV strategy. All measurements were performed on a thorax phantom with Gafchromic films while dosimetric plans were computed using the Acuros XB algorithm (Varian). RESULTS We obtained the best compromise between measured surface dose (mean dose and homogeneity) and skin toxicity threshold obtained from the literature using a daily 3 mm thick bolus. Mean surface doses were 91.4 ± 2.8% [85.7% - 95.4%] and 92.2 ± 2.3% [85.6% - 95.2%] of the prescribed dose with IMRT and VMAT techniques, respectively. Our standard 6 MV alternate days 5 mm thick bolus leads to 89.0 ± 3.7% [83.6% - 95.5%]. Mean dose differences between measured and TPS results were < 3.2% for depths as low as 2 mm depth. CONCLUSION 10 MV IMRT-based protocols with a daily 3 mm thick bolus produce a surface dose comparable to the standard 6 MV 5 mm thick bolus on alternate days method but with an improved surface dose homogeneity. This allows for a better control of skin toxicity and target volume coverage.
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Affiliation(s)
- Frédéric A Miéville
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland.
| | - Nicolas Pitteloud
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Vérane Achard
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Giorgio Lamanna
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Olivier Pisaturo
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Pierre-Alain Tercier
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
| | - Abdelkarim S Allal
- Department of Radiation Oncology, Hôpital Fribourgeois, 2-6 Chemin des Pensionnats, 1752 Villars-sur-Glâne, Fribourg, Switzerland
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van Marlen P, van de Water S, Dahele M, Slotman BJ, Verbakel WFAR. Single Ultra-High Dose Rate Proton Transmission Beam for Whole Breast FLASH-Irradiation: Quantification of FLASH-Dose and Relation with Beam Parameters. Cancers (Basel) 2023; 15:cancers15092579. [PMID: 37174045 PMCID: PMC10177419 DOI: 10.3390/cancers15092579] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/25/2023] [Accepted: 04/27/2023] [Indexed: 05/15/2023] Open
Abstract
Healthy tissue-sparing effects of FLASH (≥40 Gy/s, ≥4-8 Gy/fraction) radiotherapy (RT) make it potentially useful for whole breast irradiation (WBI), since there is often a lot of normal tissue within the planning target volume (PTV). We investigated WBI plan quality and determined FLASH-dose for various machine settings using ultra-high dose rate (UHDR) proton transmission beams (TBs). While five-fraction WBI is commonplace, a potential FLASH-effect might facilitate shorter treatments, so hypothetical 2- and 1-fraction schedules were also analyzed. Using one tangential 250 MeV TB delivering 5 × 5.7 Gy, 2 × 9.74 Gy or 1 × 14.32 Gy, we evaluated: (1) spots with equal monitor units (MUs) in a uniform square grid with variable spacing; (2) spot MUs optimized with a minimum MU-threshold; and (3) splitting the optimized TB into two sub-beams: one delivering spots above an MU-threshold, i.e., at UHDRs; the other delivering the remaining spots necessary to improve plan quality. Scenarios 1-3 were planned for a test case, and scenario 3 was also planned for three other patients. Dose rates were calculated using the pencil beam scanning dose rate and the sliding-window dose rate. Various machine parameters were considered: minimum spot irradiation time (minST): 2 ms/1 ms/0.5 ms; maximum nozzle current (maxN): 200 nA/400 nA/800 nA; two gantry-current (GC) techniques: energy-layer and spot-based. For the test case (PTV = 819 cc) we found: (1) a 7 mm grid achieved the best balance between plan quality and FLASH-dose for equal-MU spots; (2) near the target boundary, lower-MU spots are necessary for homogeneity but decrease FLASH-dose; (3) the non-split beam achieved >95% FLASH for favorable (not clinically available) machine parameters (SB GC, low minST, high maxN), but <5% for clinically available settings (EB GC, minST = 2 ms, maxN = 200 nA); and (4) splitting gave better plan quality and higher FLASH-dose (~50%) for available settings. The clinical cases achieved ~50% (PTV = 1047 cc) or >95% (PTV = 477/677 cc) FLASH after splitting. A single UHDR-TB for WBI can achieve acceptable plan quality. Current machine parameters limit FLASH-dose, which can be partially overcome using beam-splitting. WBI FLASH-RT is technically feasible.
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Affiliation(s)
- Patricia van Marlen
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Steven van de Water
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Max Dahele
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Berend J Slotman
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
| | - Wilko F A R Verbakel
- Department of Radiation Oncology, Amsterdam UMC, Vrije Universiteit Amsterdam, Cancer Center Amsterdam, De Boelelaan 1117, 1118, 1081 HV Amsterdam, The Netherlands
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He Y, Chen S, Gao X, Fu L, Kang Z, Liu J, Shi L, Li Y. Robustness of VMAT to setup errors in postmastectomy radiotherapy of left-sided breast cancer: Impact of bolus thickness. PLoS One 2023; 18:e0280456. [PMID: 36693073 PMCID: PMC9873183 DOI: 10.1371/journal.pone.0280456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 12/30/2022] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Volumetric modulated arc therapy (VMAT) with varied bolus thicknesses has been employed in postmastectomy radiotherapy (PMRT) of breast cancer to improve superficial target coverage. However, impact of bolus thickness on plan robustness remains unclear. METHODS The study enrolled ten patients with left-sided breast cancer who received radiotherapy using VMAT with 5 mm and 10 mm bolus (VMAT-5B and VMAT-10B). Inter-fractional setup errors were simulated by introducing a 3 mm shift to isocenter of the original plans in the anterior-posterior, left-right, and inferior-superior directions. The plans (perturbed plans) were recalculated without changing other parameters. Dose volume histograms (DVH) were collected for plan evaluation. Absolute dose differences in DVH endpoints for the clinical target volume (CTV), heart, and left lung between the perturbed plans and the original ones were used for robustness analysis. RESULTS VMAT-10B showed better target coverage, while VMAT-5B was superior in organs-at-risk (OARs) sparing. As expected, small setup errors of 3 mm could induce dose fluctuations in CTV and OARs. The differences in CTV were small in VMAT-5B, with a maximum difference of -1.05 Gy for the posterior shifts. For VMAT-10B, isocenter shifts in the posterior and right directions significantly decreased CTV coverage. The differences were -1.69 Gy, -1.48 Gy and -1.99 Gy, -1.69 Gy for ΔD95% and ΔD98%, respectively. Regarding the OARs, only isocenter shifts in the posterior, right, and inferior directions increased dose to the left lung and the heart. Differences in VMAT-10B were milder than those in VMAT-5B. Specifically, mean heart dose were increased by 0.42 Gy (range 0.10 ~ 0.95 Gy) and 0.20 Gy (range -0.11 ~ 0.72 Gy), and mean dose for the left lung were increased by 1.02 Gy (range 0.79 ~ 1.18 Gy) and 0.68 Gy (range 0.47 ~ 0.84 Gy) in VMAT-5B and VMAT-10B, respectively. High-dose volumes in the organs were increased by approximate 0 ~ 2 and 1 ~ 3 percentage points, respectively. Nevertheless, most of the dosimetric parameters in the perturbed plans were still clinically acceptable. CONCLUSIONS VMAT-5B appears to be more robust to 3 mm setup errors than VMAT-10B. VMAT-5B also resulted in better OARs sparing with acceptable target coverage and dose homogeneity. Therefore 5 mm bolus is recommended for PMRT of left-sided breast cancer using VMAT.
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Affiliation(s)
- Yipeng He
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Sijia Chen
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Xiang Gao
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Lirong Fu
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Zheng Kang
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Jun Liu
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Liwan Shi
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Yimin Li
- Department of Radiation Oncology, The First Affiliated Hospital of Xiamen University, Xiamen, China
- * E-mail:
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Nour Y, Pöttgen C, Kebir S, Lazaridis L, Lüdemann L, Guberina M, Gauler T, Scheffler B, Jabbarli R, Pierscianek D, Sure U, Schmidt T, Oster C, Hau P, Glas M, Lübcke W, Stuschke M, Guberina N. Dosimetric impact of the positioning variation of tumor treating field electrodes in the PriCoTTF-phase I/II trial. J Appl Clin Med Phys 2021; 22:242-250. [PMID: 33389825 PMCID: PMC7856507 DOI: 10.1002/acm2.13144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 11/06/2020] [Accepted: 12/04/2020] [Indexed: 12/25/2022] Open
Abstract
Purpose The aim of the present study based on the PriCoTTF‐phase I/II trial is the quantification of skin‐normal tissue complication probabilities of patients with newly diagnosed glioblastoma multiforme treated with Tumor Treating Field (TTField) electrodes, concurrent radiotherapy, and temozolomide. Furthermore, the skin‐sparing effect by the clinically applied strategy of repetitive transducer array fixation around their center position shall be examined. Material and Methods Low‐dose cone‐beam computed tomography (CBCT) scans of all fractions of the first seven patients of the PriCoTTF‐phase I/II trial, used for image guidance, were applied for the dosimetric analysis, for precise TTField transducer array positioning and contour delineation. Within this trial, array positioning was varied from fixation‐to‐fixation period with a standard deviation of 1.1 cm in the direction of the largest variation of positioning and 0.7 cm in the perpendicular direction. Physical TTField electrode composition was examined and a respective Hounsfield Unit attributed to the TTField electrodes. Dose distributions in the planning CT with TTField electrodes in place, as derived from prefraction CBCTs, were calculated and accumulated with the algorithm Acuros XB. Dose‐volume histograms were obtained for the first and second 2 mm scalp layer with and without migrating electrodes and compared with those with fixed electrodes in an average position. Skin toxicity was quantified according to Lyman's model. Minimum doses in hot‐spots of 0.05 cm2 and 25 cm2 (ΔD0.05cm2, ΔD25cm2) size in the superficial skin layers were analyzed. Results Normal tissue complication probabilities (NTCPs) for skin necrosis ranged from 0.005% to 1.474% (median 0.111%) for the different patients without electrodes. NTCP logarithms were significantly dependent on patient (P < 0.0001) and scenario (P < 0.0001) as classification variables. Fixed positioning of TTField arrays increased skin‐NTCP by a factor of 5.50 (95%, CI: 3.66–8.27). The variation of array positioning increased skin‐NTCP by a factor of only 3.54 (95%, CI: 2.36–5.32) (P < 0.0001, comparison to irradiation without electrodes; P = 0.036, comparison to irradiation with fixed electrodes). NTCP showed a significant rank correlation with D25cm2 over all patients and scenarios (rs = 0.76; P < 0.0001). Conclusion Skin‐NTCP calculation uncovers significant interpatient heterogeneity and may be used to stratify patients into high‐ and low‐risk groups of skin toxicity. Array position variation may mitigate about one‐third of the increase in surface dose and skin‐NTCP by the TTField electrodes.
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Affiliation(s)
- Youness Nour
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Christoph Pöttgen
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Sied Kebir
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Lazaros Lazaridis
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Lutz Lüdemann
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Maja Guberina
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Thomas Gauler
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Björn Scheffler
- DKFZ-Division Translational Neurooncology at the West German Cancer Centre (WTZ), German Cancer Consortium (DKTK), Partner Site University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Ramazan Jabbarli
- Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Daniela Pierscianek
- Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Ulrich Sure
- German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany.,Department of Neurosurgery, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Teresa Schmidt
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Christoph Oster
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Peter Hau
- Department of Neurology and Wilhelm Sander-NeuroOncology Unit, Regensburg University Hospital, Germany
| | - Martin Glas
- Division of Clinical Neurooncology, Department of Neurology and West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Wolfgang Lübcke
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
| | - Martin Stuschke
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany.,German Cancer Consortium (DKTK), Partner Site University Hospital Essen, Germany
| | - Nika Guberina
- Department of Radiotherapy, West German Cancer Center, University Hospital Essen, University of Duisburg, Essen, Germany
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