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Harrington K, Hall E, Hawkins M, Henry A, MacKay R, Maughan T, McDonald A, Nutting C, Oelfke U, Sebag-Montefiore D, Sharma RA, van Herk M, Faivre-Finn C. Introducing the Cancer Research UK Advanced Radiotherapy Technologies Network (ART-NET). Clin Oncol (R Coll Radiol) 2017; 29:707-710. [PMID: 28807360 PMCID: PMC6155492 DOI: 10.1016/j.clon.2017.07.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 06/30/2017] [Accepted: 07/08/2017] [Indexed: 12/25/2022]
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52
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Tsang HS, Kamerling CP, Ziegenhein P, Nill S, Oelfke U. A novel probabilistic approach to generating PTV with partial voxel contributions. Phys Med Biol 2017; 62:4917-4928. [PMID: 28379156 PMCID: PMC5953212 DOI: 10.1088/1361-6560/aa6b90] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/21/2017] [Accepted: 04/05/2017] [Indexed: 12/25/2022]
Abstract
Radiotherapy treatment planning for use with high-energy photon beams currently employs a binary approach in defining the planning target volume (PTV). We propose a margin concept that takes the beam directions into account, generating beam-dependent PTVs (bdPTVs) on a beam-by-beam basis. The resulting degree of overlaps between the bdPTVs are used within the optimisation process; the optimiser effectively considers the same voxel to be both target and organ at risk (OAR) with fractional contributions. We investigate the impact of this novel approach when applied to prostate radiotherapy treatments, and compare treatment plans generated using beam dependent margins to conventional margins. Five prostate patients were used in this planning study, and plans using beam dependent margins improved the sparing of high doses to target-surrounding OARs, though a trade-off in delivering additional low dose to the OARs can be observed. Plans using beam dependent margins are observed to have a slightly reduced target coverage. Nevertheless, all plans are able to satisfy 90% population coverage with the target receiving at least 95% of the prescribed dose to [Formula: see text].
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53
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Merrem A, Bartzsch S, Laissue J, Oelfke U. Computational modelling of the cerebral cortical microvasculature: effect of x-ray microbeams versus broad beam irradiation. Phys Med Biol 2017; 62:3902-3922. [PMID: 28333689 PMCID: PMC6050522 DOI: 10.1088/1361-6560/aa68d5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 03/15/2017] [Accepted: 03/23/2017] [Indexed: 12/31/2022]
Abstract
Microbeam Radiation Therapy is an innovative pre-clinical strategy which uses arrays of parallel, tens of micrometres wide kilo-voltage photon beams to treat tumours. These x-ray beams are typically generated on a synchrotron source. It was shown that these beam geometries allow exceptional normal tissue sparing from radiation damage while still being effective in tumour ablation. A final biological explanation for this enhanced therapeutic ratio has still not been found, some experimental data support an important role of the vasculature. In this work, the effect of microbeams on a normal microvascular network of the cerebral cortex was assessed in computer simulations and compared to the effect of homogeneous, seamless exposures at equal energy absorption. The anatomy of a cerebral microvascular network and the inflicted radiation damage were simulated to closely mimic experimental data using a novel probabilistic model of radiation damage to blood vessels. It was found that the spatial dose fractionation by microbeam arrays significantly decreased the vascular damage. The higher the peak-to-valley dose ratio, the more pronounced the sparing effect. Simulations of the radiation damage as a function of morphological parameters of the vascular network demonstrated that the distribution of blood vessel radii is a key parameter determining both the overall radiation damage of the vasculature and the dose-dependent differential effect of microbeam irradiation.
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Bernstein D, Taylor A, Nill S, Oelfke U. EP-1715: Differences in delineation uncertainty using MR images only vs CT-MR in recurrent gynaecological GTV. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)32247-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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55
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Menten M, Bainbridge H, Fast M, Nill S., McDonald F, Oelfke U. PO-0916: Feasibility and potential for treating locally advanced non-small cell lung cancer with a MR-linac. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)31353-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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56
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Pathmanathan A, Mitchell A, Thomas K, Henderson D, Nill S, Oelfke U, Huddart R, Van As N, Tree A. PO-0828: Stereotactic body radiotherapy (SBRT) for localised prostate cancer on the MR-Linac. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)31265-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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57
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Eiben B, Fast M, Menten M, Bromma K, Wetscherek A, Hawkes D, McClelland J, Oelfke U. OC-0155: Automated lung tumour delineation in cine MR images for image guided radiotherapy with an MR-Linac. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)30598-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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58
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Gulliford S, Griffin C, Tree A, Murray J, Oelfke U, Syndikus I, Hall E, Dearnaley D. EP-1612: Estimates of the α/β ratio for prostate using data from recent hypofractionated RT trials. Radiother Oncol 2017. [DOI: 10.1016/s0167-8140(17)32047-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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59
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Guerreiro F, Burgos N, Dunlop A, Wong K, Petkar I, Nutting C, Harrington K, Bhide S, Newbold K, Dearnaley D, deSouza NM, Morgan VA, McClelland J, Nill S, Cardoso MJ, Ourselin S, Oelfke U, Knopf AC. Evaluation of a multi-atlas CT synthesis approach for MRI-only radiotherapy treatment planning. Phys Med 2017; 35:7-17. [PMID: 28242137 PMCID: PMC5368286 DOI: 10.1016/j.ejmp.2017.02.017] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 01/27/2017] [Accepted: 02/14/2017] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND AND PURPOSE Computed tomography (CT) imaging is the current gold standard for radiotherapy treatment planning (RTP). The establishment of a magnetic resonance imaging (MRI) only RTP workflow requires the generation of a synthetic CT (sCT) for dose calculation. This study evaluates the feasibility of using a multi-atlas sCT synthesis approach (sCTa) for head and neck and prostate patients. MATERIAL AND METHODS The multi-atlas method was based on pairs of non-rigidly aligned MR and CT images. The sCTa was obtained by registering the MRI atlases to the patient's MRI and by fusing the mapped atlases according to morphological similarity to the patient. For comparison, a bulk density assignment approach (sCTbda) was also evaluated. The sCTbda was obtained by assigning density values to MRI tissue classes (air, bone and soft-tissue). After evaluating the synthesis accuracy of the sCTs (mean absolute error), sCT-based delineations were geometrically compared to the CT-based delineations. Clinical plans were re-calculated on both sCTs and a dose-volume histogram and a gamma analysis was performed using the CT dose as ground truth. RESULTS Results showed that both sCTs were suitable to perform clinical dose calculations with mean dose differences less than 1% for both the planning target volume and the organs at risk. However, only the sCTa provided an accurate and automatic delineation of bone. CONCLUSIONS Combining MR delineations with our multi-atlas CT synthesis method could enable MRI-only treatment planning and thus improve the dosimetric and geometric accuracy of the treatment, and reduce the number of imaging procedures.
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Glitzner M, Fast MF, de Senneville BD, Nill S, Oelfke U, Lagendijk JJW, Raaymakers BW, Crijns SPM. Real-time auto-adaptive margin generation for MLC-tracked radiotherapy. Phys Med Biol 2017; 62:186-201. [PMID: 27991457 PMCID: PMC5952335 DOI: 10.1088/1361-6560/62/1/186] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Revised: 10/16/2016] [Accepted: 11/09/2016] [Indexed: 11/12/2022]
Abstract
In radiotherapy, abdominal and thoracic sites are candidates for performing motion tracking. With real-time control it is possible to adjust the multileaf collimator (MLC) position to the target position. However, positions are not perfectly matched and position errors arise from system delays and complicated response of the electromechanic MLC system. Although, it is possible to compensate parts of these errors by using predictors, residual errors remain and need to be compensated to retain target coverage. This work presents a method to statistically describe tracking errors and to automatically derive a patient-specific, per-segment margin to compensate the arising underdosage on-line, i.e. during plan delivery. The statistics of the geometric error between intended and actual machine position are derived using kernel density estimators. Subsequently a margin is calculated on-line according to a selected coverage parameter, which determines the amount of accepted underdosage. The margin is then applied onto the actual segment to accommodate the positioning errors in the enlarged segment. The proof-of-concept was tested in an on-line tracking experiment and showed the ability to recover underdosages for two test cases, increasing [Formula: see text] in the underdosed area about [Formula: see text] and [Formula: see text], respectively. The used dose model was able to predict the loss of dose due to tracking errors and could be used to infer the necessary margins. The implementation had a running time of 23 ms which is compatible with real-time requirements of MLC tracking systems. The auto-adaptivity to machine and patient characteristics makes the technique a generic yet intuitive candidate to avoid underdosages due to MLC tracking errors.
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Colvill E, Booth J, Nill S, Fast M, Bedford J, Oelfke U, Nakamura M, Poulsen P, Hansen R, Worm E, Ravkilde T, Rydhoeg JS, Pommer T, Munck Af Rosenschoeld P, Lang S, Guckenberger M, Groh C, Herrmann C, Verellen D, Poels K, Wang L, Hadsell M, Blanck O, Sothmann T, Keall P. TH-AB-303-01: Benchmarking Real-Time Adaptive Radiotherapy Systems: A Multi- Platform Multi-Institutional Study. Med Phys 2016. [DOI: 10.1118/1.4926156] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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62
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Bainbridge H, Menten M, Fast M, Nill S, Nutting C, Harrington K, Oelfke U, McDonald F. Dosimetric Implications for Radical Radiation Therapy on the Magnetic Resonance–Linear Accelerator (MRL) in Locally Advanced Non-Small Cell Lung Cancer (LA NSCLC). Int J Radiat Oncol Biol Phys 2016. [DOI: 10.1016/j.ijrobp.2016.06.1803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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63
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Oelfke U, Bortfeld T. Optimization of Physical Dose Distributions with Hadron Beams: Comparing Photon IMRT with IMPT. Technol Cancer Res Treat 2016; 2:401-12. [PMID: 14529305 DOI: 10.1177/153303460300200505] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Intensity modulated radiotherapy with high enengy photons (IMRT) and with charged particles (IMPT) refer to the most advanced development in conformal radiation therapy. Their general aim is to increase local tumor control rates while keeping the radiation induced complications below desired thresholds. IMRT is currently widely introduced in clinical practice. However, the more complicated IMPT is still under development. Especially, spot-scanning techniques integrated in rotating gantries that can deliver proton or light ion-beams to a radiation target from any direction will be available in the near future. We describe the basic concepts of intensity modulated particle therapy (IMPT). Starting from the potential advantages of hadron therapy inverse treatment planning strategies are discussed for various dose delivery techniques of IMPT. Of special interest are the techniques of distal edge tracking (DET) and 3D-scanning. After the introduction of these concepts a study of comparative inverse treatment planning is presented. The study aims to identify the potential advantages of achievable physical dose distributions with proton and carbon beams, if different dose delivery techniques are employed. Moreover, a comparison to standard photon IMRT is performed. The results of the study are summarized as: i) IMRT with photon beams is a strong competitor to intensity modulated radiotherapy with charged particles. The most obvious benefit observed for charged particles is the reduction of medium and low doses in organs at risk. ii) The 3D-scanning technique could not improve the dosimetric results achieved with DET, although 10–15 times more beam spots were employed for 3D-scanning than for DET. However, concerns may arise about the application of DET, if positioning errors of the patient or organ movements have to be accounted for. iii) Replacing protons with carbon ions leads to further improvements of the physical dose distributions. However, the additional degree of improvement due to carbon ions is modest. The main clinical potential of heavy ion beams is probably related to their radiobiological properties.
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Kamerling CP, Fast MF, Ziegenhein P, Nill S, Oelfke U. TH-CD-202-12: Online Inter-Beam Replanning Based On Real-Time Dose Reconstruction. Med Phys 2016. [DOI: 10.1118/1.4958169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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65
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Bernstein D, Kamerling C, Nill S, Taylor A, Oelfke U. SU-C-BRB-04: Delineation Uncertainty Maps: Proof of Concept Study for Recurrent Gynaecological Cancers. Med Phys 2016. [DOI: 10.1118/1.4955558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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66
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Glitzner M, Fast M, Denis de Senneville B, Nill S, Oelfke U, Lagendijk J, Raaymakers B, Crijns S. TH-AB-202-04: Auto-Adaptive Margin Generation for MLC-Tracked Radiotherapy. Med Phys 2016. [DOI: 10.1118/1.4958068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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67
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Tsang H, Kamerling CP, Ziegenhein P, Nill S, Oelfke U. WE-AB-209-08: Novel Beam-Specific Adaptive Margins for Reducing Organ-At-Risk Doses. Med Phys 2016. [DOI: 10.1118/1.4957777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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68
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Menten MJ, Fast MF, Nill S, Oelfke U. SU-G-BRA-16: Target Dose Comparison for Dynamic MLC Tracking and Mid- Ventilation Planning in Lung Radiotherapy Subject to Intrafractional Baseline Drifts. Med Phys 2016. [DOI: 10.1118/1.4956940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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69
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Reinhart M, Fast MF, Nill S, Oelfke U. SU-F-T-672: A Novel Kernel-Based Dose Engine for KeV Photon Beams. Med Phys 2016. [DOI: 10.1118/1.4956858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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70
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Kieselmann J, Bartzsch S, Oelfke U. TU-AB-BRC-06: Dose Calculation in Curved Space. Med Phys 2016. [DOI: 10.1118/1.4957400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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71
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Fast M, Kamerling C, Crijns S, Menten M, Nill S, Raaymakers B, Oelfke U. TH-AB-202-03: A Novel Tool for Computing Deliverable Doses in Dynamic MLC Tracking Treatments. Med Phys 2016. [DOI: 10.1118/1.4958067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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72
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Donzelli M, Braeuer-Krisch E, Oelfke U. PO-0885: Brain motion induced artefacts in microbeam radiation therapy: a Monte Carlo study. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)32135-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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73
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Tsang H, Kamerling C, Nill S, Oelfke U. OC-0380: Moving away from binary definition of PTVs: a novel probabilistic approach to PTV definition. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)31629-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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74
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Fast MF, Kamerling CP, Ziegenhein P, Menten MJ, Bedford JL, Nill S, Oelfke U. Assessment of MLC tracking performance during hypofractionated prostate radiotherapy using real-time dose reconstruction. Phys Med Biol 2016; 61:1546-62. [PMID: 26816273 PMCID: PMC5390952 DOI: 10.1088/0031-9155/61/4/1546] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 11/25/2015] [Accepted: 12/16/2015] [Indexed: 11/16/2022]
Abstract
By adapting to the actual patient anatomy during treatment, tracked multi-leaf collimator (MLC) treatment deliveries offer an opportunity for margin reduction and healthy tissue sparing. This is assumed to be especially relevant for hypofractionated protocols in which intrafractional motion does not easily average out. In order to confidently deliver tracked treatments with potentially reduced margins, it is necessary to monitor not only the patient anatomy but also the actually delivered dose during irradiation. In this study, we present a novel real-time online dose reconstruction tool which calculates actually delivered dose based on pre-calculated dose influence data in less than 10 ms at a rate of 25 Hz. Using this tool we investigate the impact of clinical target volume (CTV) to planning target volume (PTV) margins on CTV coverage and organ-at-risk dose. On our research linear accelerator, a set of four different CTV-to-PTV margins were tested for three patient cases subject to four different motion conditions. Based on this data, we can conclude that tracking eliminates dose cold spots which can occur in the CTV during conventional deliveries even for the smallest CTV-to-PTV margin of 1 mm. Changes of organ-at-risk dose do occur frequently during MLC tracking and are not negligible in some cases. Intrafractional dose reconstruction is expected to become an important element in any attempt of re-planning the treatment plan during the delivery based on the observed anatomy of the day.
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Donzelli M, Bräuer-Krisch E, Oelfke U. Brain motion induced artefacts in Microbeam Radiation Therapy: a Monte Carlo study. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)30070-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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