Automatic Substitute Computed Tomography Generation and Contouring for Magnetic Resonance Imaging (MRI)-Alone External Beam Radiation Therapy From Standard MRI Sequences

Dowling, Jason; Sun, Jidi; Pichler, Peter-Paul; Rivest-Hénault, David; Ghose, Soumya; Richardson, Haylea; Wratten, Chris; Martin, Jarad; Arm, Jameen; Best, Leah; Chandra, Shekhar S.; Fripp, Jürgen; Menk, F. W.; Greer, Peter B.

doi:10.1016/j.ijrobp.2015.08.045

Cited by 154 publications

(251 citation statements)

References 40 publications

Supporting

Mentioning

229

Contrasting

Unclassified

Order By: Relevance

“…However with MRXT, there has been success in directly converting MRI to pseudo or substitute CT images which can accurately reproduce the electron density information used for dose planning. 38,39,40 Such methods eliminate the requirement to acquire an initial patient CT dataset, while preserving the inherent soft tissue delineation shown in the MRI data. As described in Section 1.C, similar studies have been performed for proton therapy-based planning with mixed but promising results.…”

Section: A Mri-only Proton Therapy Planningmentioning

confidence: 99%

Future of medical physics: Real‐time MRI‐guided proton therapy

et al. 2017

View full text Add to dashboard Cite

With the recent clinical implementation of real-time MRI-guided x-ray beam therapy (MRXT), attention is turning to the concept of combining real-time MRI guidance with proton beam therapy; MRIguided proton beam therapy (MRPT). MRI guidance for proton beam therapy is expected to offer a compelling improvement to the current treatment workflow which is warranted arguably more than for x-ray beam therapy. This argument is born out of the fact that proton therapy toxicity outcomes are similar to that of the most advanced IMRT treatments, despite being a fundamentally superior particle for cancer treatment. In this Future of Medical Physics article, we describe the various software and hardware aspects of potential MRPT systems and the corresponding treatment workflow. Significant software developments, particularly focused around adaptive MRI-based planning will be required. The magnetic interaction between the MRI and the proton beamline components will be a key area of focus. For example, the modeling and potential redesign of a magnetically compatible gantry to allow for beam delivery from multiple angles towards a patient located within the bore of an MRI scanner. Further to this, the accuracy of pencil beam scanning and beam monitoring in the presence of an MRI fringe field will require modeling, testing, and potential further development to ensure that the highly targeted radiotherapy is maintained. Looking forward we envisage a clear and accelerated path for hardware development, leveraging from lessons learnt from MRXT development. Within few years, simple prototype systems will likely exist, and in a decade, we could envisage coupled systems with integrated gantries. Such milestones will be key in the development of a more efficient, more accurate, and more successful form of proton beam therapy for many common cancer sites.

show abstract

Section: A Mri-only Proton Therapy Planningmentioning

confidence: 99%

Future of medical physics: Real‐time MRI‐guided proton therapy

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The proposed MRI only workflows for EBRT of prostate present in the literature all depend on separate MRI sequences for GFM identification, target delineation, and sCT generation. 12,25,33,34 The use of separate sequences is unfavorable due to several reasons. First, multiple sequences increase the examination time.…”

Section: Introductionmentioning

confidence: 99%

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

et al. 2017

View full text Add to dashboard Cite

Purpose: The superior soft tissue contrast of magnetic resonance imaging (MRI) compared to computed tomography (CT) has urged the integration of MRI and elimination of CT in radiotherapy treatment (RT) for prostate. An intraprostatic gold fiducial marker (GFM) appears hyperintense on CT. On T2-weighted (T2w) MRI target delineation images, the GFM appear as a small signal void similar to calcifications and post biopsy fibrosis. It can therefore be difficult to identify the markers without CT. Detectability of GFMs can be improved using additional MR images, which are manually registered to target delineation images. This task requires manual labor, and is associated with interoperator differences and image registration errors. The aim of this work was to develop and evaluate an automatic method for identification of GFMs directly in the target delineation images without the need for image registration. Methods: T2w images, intended for target delineation, and multiecho gradient echo (MEGRE) images intended for GFM identification, were acquired for prostate cancer patients. Signal voids in the target delineation images were identified as GFM candidates. The GFM appeared as round, symmetric, signal void with increasing area for increasing echo time in the MEGRE images. These image features were exploited for automatic identification of GFMs in a MATLAB model using a patient training dataset (n = 20). The model was validated on an independent patient dataset (n = 40). The distances between the identified GFM in the target delineation images and the GFM in CT images were measured. A human observatory study was conducted to validate the use of MEGRE images. Results: The sensitivity, specificity, and accuracy of the automatic method and the observatory study was 84%, 74%, 81% and 98%, 94%, 97%, respectively. The mean absolute difference in the GFM distances for the automatic method and observatory study was 1.28 AE 1.25 mm and 1.14 AE 1.06 mm, respectively. Conclusions: Multiecho gradient echo images were shown to be a feasible and reliable way to perform GFM identification. For clinical practice, visual inspection of the results from the automatic method is needed at the current stage.

show abstract

“…3, where we observe that an increase in segmentation overlap corresponds to a decrease in CT synthesis error. When evaluating the segmentation accuracy obtained with their method, Dowling et al [8] reported mean DSCs of 0.80, 0.86 and 0.84 for the prostate, bladder and rectum, respectively. Wong et al [12] assessed the performance of several multi-atlas segmentation methods.…”

Section: Discussionmentioning

confidence: 99%

“…The technique was later extended to the synthesis of images by propagating intensity images instead of segmented images, for example CT images [3]. Multi-atlas CT synthesis methods have been developed for RTP [4][5][6] but only a few have been applied outside of the brain [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…This is not guaranteed if the segmentation and CT synthesis tasks are handled separately. Dowling et al [8] proposed to combine CT synthesis and segmentation using a database of atlases each composed of an MR, a CT and a segmented image. The atlas MR images were first registered to the target MR image and the same transformations were applied to both the atlas CT and segmented images.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Joint Segmentation and CT Synthesis for MRI-only Radiotherapy Treatment Planning

Burgos

Guerreiro

McClelland

et al. 2016

Medical Image Computing and Computer-Assisted Intervention – MICCAI 2016

View full text Add to dashboard Cite

Abstract. Accurate knowledge of organ location and tissue attenuation properties are the two essential components to perform radiotherapy treatment planning (RTP). Computed tomography (CT) has been the modality of choice for RTP as it easily provides electron density information. However, its low soft tissue contrast limits the accuracy of organ delineation. On the contrary, magnetic resonance (MR) provides images with excellent soft tissue contrast but its use for RTP is limited by the fact that it does not readily provide tissue attenuation information. In this work we propose a multi-atlas information propagation scheme that jointly segments the organs at risk and generates pseudo CT data from MR images. We demonstrate that the proposed framework is able to automatically generate accurate pseudo CT images and segmentations in the pelvic region, bypassing the need for CT scan for accurate RTP.

show abstract

Automatic Substitute Computed Tomography Generation and Contouring for Magnetic Resonance Imaging (MRI)-Alone External Beam Radiation Therapy From Standard MRI Sequences

Abstract: The MR-Sim setup and automatic sCT generation methods using standard MR sequences generates realistic contours and electron densities for prostate cancer radiation therapy dose planning and digitally reconstructed radiograph generation.

Cited by 154 publications

References 40 publications

Future of medical physics: Real‐time MRI‐guided proton therapy

Future of medical physics: Real‐time MRI‐guided proton therapy

Registration free automatic identification of gold fiducial markers in MRI target delineation images for prostate radiotherapy

Joint Segmentation and CT Synthesis for MRI-only Radiotherapy Treatment Planning

Contact Info

Product

Resources

About