Automatic reconstruction of the delivered dose of the day using MR-linac treatment log files and online MR imaging

Menten, Martin J.; Mohajer, J.; Nilawar, Rahul; Bertholet, Jenny; Dunlop, A.; Pathmanathan, A.; Moreau, M.; Marshall, S. G.; Wetscherek, Andreas; Nill, Simeon; Tree, A.; Oelfke, Uwe

doi:10.1016/j.radonc.2019.12.010

Cited by 58 publications

(81 citation statements)

References 36 publications

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“…We utilized 3D cine-MR with high spatial and temporal frequency to extract the prostate motion with six degrees of freedom instead of 2D surrogates like implanted markers [19, ] and 2D cine-MR imaging [16, ] during each fraction. Our soft-tissue based registration method yields rigid transformations and thus limits us to prostate translation and rotation excluding the tissue deformations that take place in the surrounding organs.…”

Section: Discussionmentioning

confidence: 99%

“…The PV scan was only used as reference in the limited number of fractions in which a virtual couch shift was performed to correct for unacceptable intrafraction motion compared to REF. In contrast to using the PV scan as the reference of the registration [16] , we incorporate the motion that occurred in the anatomy over the total time the patient was lying on the treatment couch prior to beam-on, thus yielding a better representation of the true delivered dose to the patient.…”

Section: Discussionmentioning

confidence: 99%

“…Previously we have published our method to calculate the impact of prostate intrafraction motion on the planned dose distribution as obtained from 3D cine-MR, but used cine-MR images that were acquired after radiotherapy, essentially simulating an online MRI-guided treatment [15] . The impact on delivered dose in MRI-guided prostate patients based on anterior-posterior (AP) and cranial-caudal (CC) translations extracted from intrafraction 2D cine-MR imaging and treatment log files was recently presented [16] .…”

Section: Introductionmentioning

confidence: 99%

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Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5T magnetic resonance imaging and linear accelerator system

Kontaxis

Keizer

Kerkmeijer

et al. 2020

Physics and Imaging in Radiation Oncology

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Background and purpose: Monitoring the intrafraction motion and its impact on the planned dose distribution is of crucial importance in radiotherapy. In this work we quantify the delivered dose for the first prostate patients treated on a combined 1.5T Magnetic Resonance Imaging (MRI) and linear accelerator system in our clinic based on online 3D cine-MR and treatment log files. Materials and methods: A prostate intrafraction motion trace was obtained with a soft-tissue based rigid registration method with six degrees of freedom from 3D cine-MR dynamics with a temporal resolution of 8.5-16.9 s. For each fraction, all dynamics were also registered to the daily MR image used during the online treatment planning, enabling the mapping to this reference point. Moreover, each fraction's treatment log file was used to extract the timestamped machine parameters during delivery and assign it to the appropriate dynamic volume. These partial plans to dynamic volume combinations were calculated and summed to yield the delivered fraction dose. The planned and delivered dose distributions were compared among all patients for a total of 100 fractions. Results: The clinical target volume underwent on average a decrease of 2.2% ± 2.9% in terms of D99% coverage while bladder V62Gy was increased by 1.6% ± 2.3% and rectum V62Gy decreased by 0.2% ± 2.2%. Conclusions: The first MR-linac dose reconstruction results based on prostate tracking from intrafraction 3D cine-MR and treatment log files are presented. Such a pipeline is essential for online adaptation especially as we progress to MRI-guided extremely hypofractionated treatments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5T magnetic resonance imaging and linear accelerator system

Kontaxis

Keizer

Kerkmeijer

et al. 2020

Physics and Imaging in Radiation Oncology

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“…Online plan adaptation, in particular where the CTV is re-contoured online, eliminates interfractional geometric uncertainty. Menten et al [29] analysed the intrafractional motion of the prostate using template matching in cine-MR for five Unity MR-Linac prostate cancer patients treated with 60 Gy in 20 fractions. For the duration of treatment delivery (5.5 ± 0.8 min), mean and standard deviation CTV positional shifts of 0.0 ± 0.8 mm (posterior direction) and 0.1 ± 0.9 mm (caudal direction) were reported.…”

Section: Discussionmentioning

confidence: 99%

Feasibility of MR-guided ultrahypofractionated radiotherapy in 5, 2 or 1 fractions for prostate cancer

Mohajer

Dunlop

Mitchell

et al. 2021

Clinical and Translational Radiation Oncology

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This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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“…With the dose delivery status recorded every 40 ms in treatment log files and online MR imaging data, the dosimetric impacts of anatomical motion for targets and OARs can be retrospectively assessed on a daily basis. 98,99 It can be possible in the future to enable real time adaptive replanning if the system is robust for reoptimizing the plan. The DIR dose accumulation, therefore, has to be very efficient (i.e., low latency) with desired automated contouring of the targets and OARs and ensured in vivo verification for patient delivery quality assurance.…”

Section: Respiratory Gating Using Internal Markersmentioning

confidence: 99%

Patient-Specific Planning Target Volume Margins for Liver Stereotactic Robotic Radiosurgery

Liu¹

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Purpose: To create analytical tools for a proposed clinical workflow, which implements patientspecific planning target volume (PTV) margins for liver radiation therapy treatments. Methods and Materials: Treatment log files are analyzed for liver treatments to assess tumour motion-tracking accuracy. A uniform PTV margin is estimated that considers motion-tracking errors and deformations, provided that the impact of uncorrected rotations is minimized. A supervised machine learning algorithm employing retrospective data, which emulates a dry-run session prior to treatment planning, is used to investigate if motion-tracking errors are less than 2 mm, and consequently, the standard PTV margins can be reduced by 2 mm. For a safer implementation in the clinic, we employ a warning system that quantifies the probability of a geographic miss if the PTV margin is reduced for every subsequent fraction. A dosimetric analytical tool is proposed to retrospectively assess the dose to a target against different types of delivery errors. The tool is validated by radiochromic film measurements for two very different types of treatments, liver and trigeminal neuralgia (a cranial nerve disorder). Case studies are conducted to access the suitability of a selected PTV margin based on the geometrical and dosimetric coverage of targets. The range of rotations that can be safely allowed for trigeminal neuralgia treatments is quantified since rotational corrections cannot be applied by the system for this specific disease site. Results: Isotropic 4 mm PTV margins are sufficient to account for tracking errors and deformations for 95% of patients. For patient-specific PTV margins, the accuracy of predicting if motion-tracking errors are less than 2 mm is 0.84 ± 0.06 using 5-fold cross-validation. Using the warning system, 11 out of 64 cases predicted to be treated with 2 mm reduced PTV margins might

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Automatic reconstruction of the delivered dose of the day using MR-linac treatment log files and online MR imaging

Cited by 58 publications

References 36 publications

Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5T magnetic resonance imaging and linear accelerator system

Delivered dose quantification in prostate radiotherapy using online 3D cine imaging and treatment log files on a combined 1.5T magnetic resonance imaging and linear accelerator system

Feasibility of MR-guided ultrahypofractionated radiotherapy in 5, 2 or 1 fractions for prostate cancer

Patient-Specific Planning Target Volume Margins for Liver Stereotactic Robotic Radiosurgery

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