MRA-guided stereotactic radiation treatment planning for cerebral angiomas

Ehricke, Hans-Heino; Schad, Lothar R.

doi:10.1016/0895-6111(92)90119-t

Cited by 13 publications

(7 citation statements)

References 22 publications

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“…Ehricke and Schad 1992 found that distortion depends very much on the condition of the scanner, namely the state of shimming and eddy currents compensation. Their experiments showed that for a given scanner condition and acquisition protocol, the spatial distortion pattern is very stable.…”

Section: Discussionmentioning

confidence: 99%

“…MR image distortions around the head may be signi cant, since some applications regarding this site require mm accuracy, e.g. stereotaxy Schad et al 1987a, stereotactic radiotherapy Ehricke and Schad 1992;Kooy et al 1994;Schad et al 1994, stereotactic neurosurgery Michiels et al 1994 and radiotherapy treatment planning of brain tumours Schad et al 1987b. Furthermore, distortions as a result of magnetic eld perturbations by external devices such as localization frames have not been fully explored yet.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic resonance imaging in radiotherapy treatment planning

Moerland¹

1997

Medical Physics

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The aim of this study is to investigate the capabilities of magnetic resonance imaging (MRI) in radiotherapy treatment planning (RTP) and to explore the MR image distortions and how these distortions can be reduced or, if necessary, corrected in order to integrate MRI into RTP in a reliable manner. Image distortions and the efficacy of correction methods were evaluated in phantom, volunteer, and patient studies. From the measurement, analysis, and correction of machine‐related geometric distortions in MRI, it was concluded that MR image corrections are necessary in applications which require mm accuracy and that correction methods, based on 3D maps of static field inhomogeneity and gradient nonlinearity, are feasible in clinical practice. From the measurement and numerical analysis of object‐related geometric distortions, it was concluded that these distortions can be reduced to the order of the pixel size by imaging at 0.5 T and using gradients on the order of 3 mT normalm−1. Furthermore, in a study on volunteers, fast MRI scan techniques were used to measure the respiration induced kidney movement and in a study on patients with prostate cancer, the value of MRI for the evaluation of brachytherapy was demonstrated. The MR image artifacts induced by the I‐125 seeds were used to evaluate the dose distributions and dose volume histograms of permanent prostate implants.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic resonance imaging in radiotherapy treatment planning

Moerland¹

1997

Medical Physics

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“…The groups at the German Cancer Research Center and University of Heidelberg have developed techniques to integrate MRI into stereotactic radiotherapy procedures of patients with lesions in the head and neck region [8,15,41]. In a study including 195 patients, a stereotactic frame attached to the patient's head was applied during imaging (CT, MRI) and irradiation [15].…”

Section: Clinical Applications Of Image Registration In Radiotherapy mentioning

confidence: 99%

Aspects of MR Image Distortions in Radiotherapy Treatment Planning

Andreo²,

2001

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Image protocols with high gradient bandwidths should be used to reduce the spatial distortions in MR images. Correction techniques based only on phantom measurements could be sufficient at low magnetic fields, while at higher fields additional corrections of patient-related distortions might be needed. Registration techniques based on matching of Landmark points located far from the magnet isocenter are especially prone to MR distortions.

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“…This means that the relationship between image space and stereotactic space cannot be expressed as a rigid-body transformation. A recent study of these effects on an up-to-date MRI scanner, and with gradient echo volume acquisitions reveals a maximum error of 1.2 mm for dis tance measurements [18], whereas another study on a variety of ma- chines gives a localization error of ±3 mm for axial slices [19]. Howev er, all studies reveal a considerable degradation of accuracy for sagittal and coronal images.…”

Section: Accuracy Of Conventional Stereotaxymentioning

confidence: 99%

“…Let us analyze these issues in some detail. Geometric distortions in MRI (tables 1, 2) [12][13][14][15][16][17][18][19] are mainly due to main field non-uni formity, but also result from eddy currents, gradient non-linearity, and differences in magnetic susceptibility, as well as chemical shift [19]. Most of these effects cause distortions in the frequency encoding direc tion, with linear displacements in direct proportion with the field anomaly, and give rise to a 'pincushion' distribution of artefact.…”

Section: Accuracy Of Conventional Stereotaxymentioning

confidence: 99%

Accuracy in Frame-Based and Frameless Stereotaxy

Kitchen¹,

Lemieux²,

Thomas³

1993

Stereotact Funct Neurosurg

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Stereotactic surgery is currently undergoing great changes with a large number of frameless methodologies being developed alongside traditional frame-based systems. As a result, there is considerable uncertainty over the future clinical roles of the numerous stereotactic options now offered. We have reviewed the current scientific issues regarding accuracy in both frame-based and frameless stereotaxy. Frame-based systems have the advantage of proven clinical utility and instrument carriage with a high degree of mechanical stability and accuracy. Frameless methods are more complex, but also more flexible, and may have wide applications in general neurosurgery if clinical efficacy is confirmed.

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MRA-guided stereotactic radiation treatment planning for cerebral angiomas

Cited by 13 publications

References 22 publications

Magnetic resonance imaging in radiotherapy treatment planning

Magnetic resonance imaging in radiotherapy treatment planning

Aspects of MR Image Distortions in Radiotherapy Treatment Planning

Accuracy in Frame-Based and Frameless Stereotaxy

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