A Device for Realtime 3D Image-Guided IMRT

Dempsey, James F.; Benoit, Danielle S. W.; Fitzsimmons, Jeffrey R.; Haghighat, Alireza; Li, J.G.; Low, Daniel A.; Mutic, Sasa; Palta, Jatinder; Romeijn, H. Edwin; Sjoden, Glenn

doi:10.1016/j.ijrobp.2005.07.349

Cited by 76 publications

(68 citation statements)

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“…Although labor intensive, this study offers an exploratory investigation into the potential use of MRI in abdominal radiotherapy, as emerging MRI-based technologies and onboard imaging devices start to become available for clinical use. 6-8 Results of this study support the use of MRI for abdominal radiotherapy planning and localization, as contouring precision was found to be adequate according to our metrics.…”

Section: Discussionsupporting

confidence: 72%

“…6-8 Onboard MRI is being investigated by many groups in aim of mitigating daily positioning inaccuracies and providing better anatomical information than standard onboard x-ray equipment for soft tissue visualization. The first clinical installation of a low-field MRI Cobalt-60 treatment device indicates real progress toward MRI-centered radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

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Segmentation precision of abdominal anatomy for MRI-based radiotherapy

et al. 2014

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The limited soft tissue visualization provided by computed tomography, the standard imaging modality for radiotherapy treatment planning and daily localization, has motivated studies on the use of magnetic resonance imaging (MRI) for better characterization of treatment sites, such as the prostate and head and neck. However, no studies have been conducted on MRI-based segmentation for the abdomen, a site that could greatly benefit from enhanced soft tissue targeting. We investigated the interobserver and intraobserver precision in segmentation of abdominal organs on MR images for treatment planning and localization. Manual segmentation of 8 abdominal organs was performed by 3 independent observers on MR images acquired from 14 healthy subjects. Observers repeated segmentation 4 separate times for each image set. Interobserver and intraobserver contouring precision was assessed by computing 3-dimensional overlap (Dice coefficient [DC]) and distance to agreement (Hausdorff distance [HD]) of segmented organs. The mean and standard deviation of intraobserver and interobserver DC and HD values were DCintraobserver = 0.89 ± 0.12, HDintraobserver = 3.6 mm ± 1.5, DCinterobserver = 0.89 ± 0.15, and HDinterobserver = 3.2 mm ± 1.4. Overall, metrics indicated good interobserver/intraobserver precision (mean DC > 0.7, mean HD < 4 mm). Results suggest that MRI offers good segmentation precision for abdominal sites. These findings support the utility of MRI for abdominal planning and localization, as emerging MRI technologies, techniques, and onboard imaging devices are beginning to enable MRI-based radiotherapy.

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Section: Discussionsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Segmentation precision of abdominal anatomy for MRI-based radiotherapy

et al. 2014

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“…Additionally, based on the growing importance of the exclusive use of MRI in radiotherapy (Raaymakers et al 2004, Dempsey et al 2005, Fallone et al 2009, we foresee that MR-based dose calculations will also be of increasing importance to radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

et al. 2017

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Magnetic resonance (MR)-only radiotherapy treatment planning requires pseudo-CT (pCT) images to enable MR-based dose calculations. To verify the accuracy of MR-based dose calculations, institutions interested in introducing MR-only planning will have to compare pCT-based and computer tomography (CT)-based dose calculations. However, interpreting such comparison studies may be challenging, since potential differences arise from a range of confounding factors which are not necessarily specific to MR-only planning. Therefore, the aim of this study is to identify and quantify the contribution of factors confounding dosimetric accuracy estimation in comparison studies between CT and pCT. The following factors were distinguished: set-up and positioning differences between imaging sessions, MR-related geometric inaccuracy, pCT generation, use of specific calibration curves to convert pCT into electron density information, and registration errors.The study comprised fourteen prostate cancer patients who underwent CT/ MRI-based treatment planning. To enable pCT generation, a commercial solution (MRCAT, Philips Healthcare, Vantaa, Finland) was adopted. IMRT plans were calculated on CT (gold standard) and pCTs. Dose difference maps in a high dose region (CTV) and in the body volume were evaluated, and the contribution to dose errors of possible confounding factors was individually quantified.We found that the largest confounding factor leading to dose difference was the use of different calibration curves to convert pCT and CT into electron density (0.7%). The second largest factor was the pCT generation Inter-scan differences due to patient repositioning, MR-related geometric inaccuracy, and registration errors did not significantly contribute to dose differences (0.01%). The proposed approach successfully identified and quantified the factors confounding accurate MRI-based dose calculation in the prostate. This study will be valuable for institutions interested in introducing MR-only dose planning in their clinical practice.

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“…Furthermore, if we assume that this imaging snap-shots the 'targets' during their intrafractional meanderings, then we can also build up a bespoke understanding of this component of positional uncertainty. An 'extreme IGRT' philosophy has been adopted by some investigators, who are advocating that the process should include interlaced or simultaneous imaging and treatment delivery, proposing the use of MR imaging [12,13] to circumvent the issue of concomitant dose. Clearly, such bold assertions need to be backedup by a model for constructing the associated adaptive therapy PTV.…”

Section: Discussionmentioning

confidence: 99%

Image-guided radiation therapy: what is our Utopia?

Beavis

2010

BJR

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A Device for Realtime 3D Image-Guided IMRT

Cited by 76 publications

References 0 publications

Segmentation precision of abdominal anatomy for MRI-based radiotherapy

Segmentation precision of abdominal anatomy for MRI-based radiotherapy

Quantification of confounding factors in MRI-based dose calculations as applied to prostate IMRT

Image-guided radiation therapy: what is our Utopia?

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