Cone beam <scp>CT</scp> for <scp>QA</scp> of synthetic <scp>CT</scp> in <scp>MRI</scp> only for prostate patients

Palmér, Emilia; Persson, Erik; Ambolt, Petra; Gustafsson, Christian Jamtheim; Gunnlaugsson, Adalsteinn; Olsson, Lars

doi:10.1002/acm2.12429

Cited by 22 publications

(23 citation statements)

References 22 publications

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“…Even though sCT dosecalculation has been widely investigated, there still seems to be a need for QA to detect large dosimetric errors. In clinical routine, the sCT error detection could be performed directly after the first fraction using CBCT [34].…”

Section: Discussionmentioning

confidence: 99%

MR-PROTECT: Clinical feasibility of a prostate MRI-only radiotherapy treatment workflow and investigation of acceptance criteria

et al. 2020

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Background: Retrospective studies on MRI-only radiotherapy have been presented. Widespread clinical implementations of MRI-only workflows are however limited by the absence of guidelines. The MR-PROTECT trial presents an MRI-only radiotherapy workflow for prostate cancer using a new single sequence strategy. The workflow incorporated the commercial synthetic CT (sCT) generation software MriPlanner™ (Spectronic Medical, Helsingborg, Sweden). Feasibility of the workflow and limits for acceptance criteria were investigated for the suggested workflow with the aim to facilitate future clinical implementations. Methods: An MRI-only workflow including imaging, post imaging tasks, treatment plan creation, quality assurance and treatment delivery was created with questionnaires. All tasks were performed in a single MR-sequence geometry, eliminating image registrations. Prospective CT-quality assurance (QA) was performed prior treatment comparing the PTV mean dose between sCT and CT dose-distributions. Retrospective analysis of the MRI-only gold fiducial marker (GFM) identification, DVH-analysis, gamma evaluation and patient setup verification using GFMs and cone beam CT were performed. Results: An MRI-only treatment was delivered to 39 out of 40 patients. The excluded patient was too large for the predefined imaging field-of-view. All tasks could successfully be performed for the treated patients. There was a maximum deviation of 1.2% in PTV mean dose was seen in the prospective CT-QA. Retrospective analysis showed a maximum deviation below 2% in the DVH-analysis after correction for rectal gas and gamma pass-rates above 98%. MRI-only patient setup deviation was below 2 mm for all but one investigated case and a maximum of 2.2 mm deviation in the GFM-identification compared to CT.

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Section: Discussionmentioning

confidence: 99%

MR-PROTECT: Clinical feasibility of a prostate MRI-only radiotherapy treatment workflow and investigation of acceptance criteria

et al. 2020

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“…The systematic review identified 6 articles investigating MR-only commissioning processes. 15,21,[35][36][37][38] A key summary of study results can be found in Table 5.…”

Section: Mr-only Commissioning Processesmentioning

confidence: 99%

“…Palmer et al 38 developed and validated a quality assurance procedure for assessing synthetic CT clinical feasibility using kV-CBCT, where CBCT scans were used to recalculate the synthetic CT treatment plan as a check of its dose calculation accuracy.…”

Section: Mr-only Commissioning Processesmentioning

confidence: 99%

“…Palmer et al 38 present a method of validating synthetic CT generations using collected patient CBCT data and provide a tool by which commissioning centers can ensure further confidence over the accuracy of their treatment planning pathway. As previously discussed by Kim et al, 36 the generation of synthetic CTs is a major risk in the MRonly pathway, and the challenge of ensuring robust patient treatment on an individual basis is nontrivial.…”

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confidence: 99%

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A Systematic Review of the Clinical Implementation of Pelvic Magnetic Resonance Imaging–Only Planning for External Beam Radiation Therapy

Bird

Henry

Sebag‐Montefiore

et al. 2019

International Journal of Radiation Oncology*Biology*Physics

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The use of magnetic resonance (MR) imaging scans alone for radiation therapy treatment planning (MR-only planning) has been highlighted as one method of improving patient outcomes. Recent technologic advances have meant that introducing MR-only planning to the clinic is becoming a reality, with several specialist radiation therapy clinics using this technique for treatment. As such, substantial efforts are being made to introduce this technique into widespread clinical implementation. A systematic review of publications investigating the clinical implementation of pelvic MR-only radiation therapy treatment planning was undertaken following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The Medline, Embase, Scopus, Science Direct, Cumulative Index to Nursing and Allied Health Literature, and Web of Science databases were searched (timespan: all years to January 2, 2019). Twenty-six articles met the inclusion criteria. The studies were grouped into the following categories: (1) MR acquisition and synthetic computed tomography generation verification, (2) MR distortion quantification and phantom development, (3) clinical validation of patient treatment positioning in an MRonly workflow, and (4) MR-only commissioning processes. Key conclusions from this review are (1) MR-only planning has been implemented clinically for prostate cancer treatments; (2) a substantial amount of work remains to translate MR-only planning into widespread clinical implementation for all pelvic sites; (3) MR scanner distortions are no longer a barrier to MR-only planning, but they must be managed appropriately; (4) MR-onlyebased patient positioning verification shows promise, but limited evidence is reported in the literature and further investigation is required; and (5) a number of MR-only commissioning processes have been reported, which can aid centers as they undertake local commissioning; however, this needs to be formalized in guidance from national bodies.

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“…The use of magnetic resonance imaging (MRI) for radiation therapy simulations has gained popularity because it provides superior soft tissue contrast compared with conventional computed tomography (CT), potentially allowing more accurate target delineation without exposing the patient to unnecessary ionizing radiation. Co‐registration of two image sets using deformable image registration (DIR) before and during treatment is used to create a foundation for delineating targets to judge the need for adaptive radiation therapy. However, DIR errors in commercial software used with MRI have not been widely reported.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the accuracy of deformable image registration on MRI with a physical phantom

Liu

Yang

et al. 2019

J Applied Clin Med Phys

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Background and purpose: Magnetic resonance imaging (MRI) has gained popularity in radiation therapy simulation because it provides superior soft tissue contrast, which facilitates more accurate target delineation compared with computed tomography (CT) and does not expose the patient to ionizing radiation. However, image registration errors in commercial software have not been widely reported. Here we evaluated the accuracy of deformable image registration (DIR) by using a physical phantom for MRI.Methods and materials: We used the "Wuphantom" for end-to-end testing of DIR accuracy for MRI. This acrylic phantom is filled with water and includes several fillable inserts to simulate various tissue shapes and properties. Deformations and changes in anatomic locations are simulated by changing the rotations of the phantom and inserts. We used Varian Velocity DIR software (v4.0) and CT (head and neck protocol) and MR (T1-and T2-weighted head protocol) images to test DIR accuracy between image modalities (MRI vs CT) and within the same image modality (MRI vs MRI) in 11 rotation deformation scenarios. Large inserts filled with Mobil DTE oil were used to simulate fatty tissue, and small inserts filled with agarose gel were used to simulate tissues slightly denser than water (e.g., prostate). Contours of all inserts were generated before DIR to provide a baseline for contour size and shape. DIR was done with the MR Correctable Deformable DIR method, and all deformed contours were compared with the original contours. The Dice similarity coefficient (DSC) and mean distance to agreement (MDA) were used to quantitatively validate DIR accuracy. We also used large and small regions of interest (ROIs) during between-modality DIR tests to simulate validation of DIR accuracy for organs at risk (OARs) and propagation of individual clinical target volume (CTV) contours.Results: No significant differences in DIR accuracy were found for T1:T1 and T2:T2 comparisons (P > 0.05). DIR was less accurate for between-modality comparisons than for same-modality comparisons, and was less accurate for T1 vs CT than for T2

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Cone beam CT for QA of synthetic CT in MRI only for prostate patients

Cited by 22 publications

References 22 publications

MR-PROTECT: Clinical feasibility of a prostate MRI-only radiotherapy treatment workflow and investigation of acceptance criteria

MR-PROTECT: Clinical feasibility of a prostate MRI-only radiotherapy treatment workflow and investigation of acceptance criteria

A Systematic Review of the Clinical Implementation of Pelvic Magnetic Resonance Imaging–Only Planning for External Beam Radiation Therapy

Evaluation of the accuracy of deformable image registration on MRI with a physical phantom

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