Assessment of dosimetric errors induced by deformable image registration methods in 4D pencil beam scanned proton treatment planning for liver tumours

Ribeiro, Cássia O.; Knopf, Antje; Langendijk, Johannes A.; Weber, Damien Charles; Lomax, Anthony; Zhang, Ye

doi:10.1016/j.radonc.2018.03.001

Cited by 45 publications

(55 citation statements)

References 29 publications

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“…This study phase sorted the 4DCTs into ten phases; however, the type of sorting and number of phases used have both been shown to affect the resulting 4D‐dose distribution; some studies indicate that using more phases and/or interpolating between phases provides more accurate 4D‐dose assessment . Many different DIR algorithms exist with variations between metrics and transformation approaches, and these differences can have dosimetric effects: the CTV volume receiving 95% of the maximum dose can vary by 5–10% between DIR algorithms . For dose accumulation, DIMs and EMTMs use DVFs with opposite directionality, and thus, a true comparison between these methods should use a DIR method which is analytically invertible.…”

Section: Discussionmentioning

confidence: 99%

“…34 Many different DIR algorithms exist with variations between metrics and transformation approaches, 66 and these differences can have dosimetric effects: the CTV volume receiving 95% of the maximum dose can vary by 5-10% between DIR algorithms. 67 For dose accumulation, DIMs and EMTMs use DVFs with opposite directionality, and thus, a true comparison between these methods should use a DIR method which is analytically invertible. The free-form style transformation of MIM used for this study is not invertible, but, as a systematic comparison is beyond the scope of this work (see, e.g., Ref.…”

Section: B Uncertainties and Limitationsmentioning

confidence: 99%

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A Monte‐Carlo‐based and GPU‐accelerated 4D‐dose calculator for a pencil beam scanning proton therapy system

et al. 2018

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Section: Discussionmentioning

confidence: 99%

Section: B Uncertainties and Limitationsmentioning

confidence: 99%

A Monte‐Carlo‐based and GPU‐accelerated 4D‐dose calculator for a pencil beam scanning proton therapy system

et al. 2018

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“…For voxel mapping, deformation vector fields were generated between the planning and control 4D‐CTs using the built‐in hybrid deformable image registration algorithm ANACONDA of the treatment planning system RayStation 6 (RaySearch, Sweden). ANACONDA combines image information, such as intensities, with anatomical information provided by contoured image sets and its performance was recently assessed in comparison to various other deformable image registration methods . In our dataset, the lungs were used as controlling region of interest.…”

Section: Methodsmentioning

confidence: 99%

“…ANACONDA combines image information, such as intensities, with anatomical information provided by contoured image sets and its performance was recently assessed in comparison to various other deformable image registration methods. 13 In our dataset, the lungs were used as controlling region of interest. The quality of the deformation vector fields was assessed by mapping and manually reviewing the structures from the reference image to the other CT image datasets as well as checking the vector fields visually for consistency and plausibility.…”

Section: C Image Registrationmentioning

confidence: 99%

Log file‐based dose reconstruction and accumulation for 4D adaptive pencil beam scanned proton therapy in a clinical treatment planning system: Implementation and proof‐of‐concept

et al. 2019

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Background and purpose Motion‐induced uncertainties hamper the clinical implementation of pencil beam scanning proton therapy (PBS‐PT). Prospective pretreatment evaluations only provide multiscenario predictions without giving a clear conclusion for the actual treatment. Therefore, in this proof‐of‐concept study we present a methodology for a fraction‐wise retrospective four‐dimensional (4D) dose reconstruction and accumulation aiming at the evaluation of treatment quality during and after treatment. Material and methods We implemented an easy‐to‐use, script‐based 4D dose assessment of PBS‐PT for patients with moving tumors in a commercially available treatment planning system. This 4D dose accumulation uses treatment delivery log files and breathing pattern records of each fraction as well as weekly repeated 4D‐CT scans acquired during the treatment course. The approach was validated experimentally and was executed for an exemplary dataset of a lung cancer patient. Results The script‐based 4D dose reconstruction and accumulation was implemented successfully, requiring minimal user input and a reasonable processing time (around 10 min for a fraction dose assessment). An experimental validation using a dynamic CIRS thorax phantom confirmed the precision of the 4D dose reconstruction methodology. In a proof‐of‐concept study, the accumulation of 33 reconstructed fraction doses showed a linear increase of D98 values. Projected treatment course D98 values revealed a CTV underdosage after fraction 25. This loss of target coverage was confirmed in a dose volume histogram comparison of the nominal, the projected (after 16 fractions) and the accumulated (after 33 fractions) dose distribution. Conclusions The presented method allows for the assessment of the conformity between planned and delivered dose as the treatment course progresses. The implemented approach considers the influence of changing patient anatomy and variations in the breathing pattern. This facilitates treatment quality evaluation and supports decisions regarding plan adaptation. In a next step, this approach will be applied to a larger patient cohort to investigate its capability as 4D quality control and decision support tool for treatment adaptation.

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“…An interesting approach has been recently proposed by Ribeiro et al . Here the authors exploit the use of ground truth DVFs extracted from a 4DMRI to be compared to estimated DVFs computed from a 4DCT‐MRI (i.e., 3DCT warped with DVFs extracted from the 4DMRI).…”

Section: The Geometric Accuracy Paradigmmentioning

confidence: 99%

“Patient‐specific validation of deformable image registration in radiation therapy: Overview and caveats”

et al. 2018

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Over the last few decades, deformable image registration (DIR) has gained popularity in image-guided radiation therapy for a number of applications, such as contour propagation, dose warping, and accumulation. Although this raises promising perspectives for the improvement of treatment outcomes and quality of radiotherapy clinical practice, the variety of proposed DIR algorithms, combined with the lack of an effective quantitative quality control metric of the registration, is slowing the transfer of DIR into the clinical routine. Recently, a task group (AAPM TG132) report was published outlining the essential aspects of DIR for image guidance in radiotherapy. However, an accurate and efficient patient-specific validation is not yet defined, and appropriate metrics should be identified to achieve the definition of both geometric and dosimetric accuracy. In this respect, the use of a dense set of anatomical landmarks, along with additional evaluations on contours or deformation field analysis, are likely to drive patient-specific DIR validation in clinical image-guided radiotherapy applications to account for geometric inaccuracies. Automatic and efficient strategies able to provide spatial information of DIR uncertainties and to evaluate monomodal and multimodal image registration, as well as to describe homogenous and un-contrasted regions are believed to represent the future direction in DIR validation. But especially in the case of DIR applications for dose mapping and accumulation, the need of accurate patient-specific validation is not only limited to the evaluation of geometric accuracy. In fact, the need to account for dosimetric inaccuracies due to DIR represents another important area in the field of adaptive treatments. Different approaches are currently being investigated to quantify the effect of DIR error on dose analysis, mainly relying on clinically relevant dose metrics, or on the study of deformation field properties for a voxel-by-voxel evaluation. However, novel research is required for the definition of dedicated and personalized measures capable to relate the geometric and dosimetric inaccuracies, thus bearing useful information for a safe use of DIR by clinical end users. In this paper we provide insights on DIR results evaluation on a patient-specific basis, facing the issues of both geometric and dosimetric paradigms. Challenges on DIR validation are overviewed and discussed, in order to push preliminary clinical guidelines forward on this fundamental topic and boost the implementation of more robust and reliable patient-specific evaluation metrics.

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Assessment of dosimetric errors induced by deformable image registration methods in 4D pencil beam scanned proton treatment planning for liver tumours

Abstract: Intrinsic geometric errors by DIR can influence the clinical evaluation of liver 4D PBS-PT plans. We recommend the use of an error bar for correctly interpreting individual 4D dose distributions.

Cited by 45 publications

References 29 publications

A Monte‐Carlo‐based and GPU‐accelerated 4D‐dose calculator for a pencil beam scanning proton therapy system

A Monte‐Carlo‐based and GPU‐accelerated 4D‐dose calculator for a pencil beam scanning proton therapy system

Log file‐based dose reconstruction and accumulation for 4D adaptive pencil beam scanned proton therapy in a clinical treatment planning system: Implementation and proof‐of‐concept

“Patient‐specific validation of deformable image registration in radiation therapy: Overview and caveats”

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