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Ong M, Schmidt A, Konstandin S, Benrath J, Eisele P, Schad L, Schönberg S, Haneder S. Cerebrale Natrium (23Na)-Bildgebung in Migränepatienten. ROFO-FORTSCHR RONTG 2017. [DOI: 10.1055/s-0037-1600402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- M Ong
- Universitätsmedizin Mannheim, Institut für klinische Radiologie und Nuklearmedizin, Mannheim
| | - A Schmidt
- Universitätsmedizin Mannheim, Institut für klinische Radiologie und Nuklearmedizin, Mannheim
| | | | - J Benrath
- Universitätsmedizin Mannheim, Klinik für Anästhesiologie und Operative Intensivmedizin, Mannheim
| | - P Eisele
- Universitätsmedizin Mannheim, Neurologische Klinik, Mannheim
| | - L Schad
- Universitätsmedizin Mannheim, Computer Assisted Clinical Medicine, Mannheim
| | - S Schönberg
- Universitätsmedizin Mannheim, Institut für klinische Radiologie und Nuklearmedizin, Mannheim
| | - S Haneder
- Universitätsklinik Köln, Institut für Diagnostische und Interventionelle Radiologie, Köln
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Rupp R, Blesch A, Schad L, Draganski B, Weidner N. [Novel aspects of diagnostics and therapy of spinal cord diseases]. Nervenarzt 2014; 85:946-54. [PMID: 25001239 DOI: 10.1007/s00115-014-4037-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
BACKGROUND Both non-traumatic and traumatic spinal cord injuries have in common that a relatively minor structural lesion can cause profound sensorimotor and autonomous dysfunction. Besides treating the cause of the spinal cord injury the main goal is to restore lost function as far as possible. AIM This article provides an overview of current innovative diagnostic (imaging) and therapeutic approaches (neurorehabilitation and neuroregeneration) aiming for recovery of function after non-traumatic and traumatic spinal cord injuries. MATERIAL AND METHODS An analysis of the current scientific literature regarding imaging, rehabilitation and rehabilitation strategies in spinal cord disease was carried out. RESULTS Novel magnetic resonance imaging (MRI) based techniques (e.g. diffusion-weighted MRI and functional MRI) allow visualization of structural reorganization and specific neural activity in the spinal cord. Robotics-driven rehabilitative measures provide training of sensorimotor function in a targeted fashion, which can even be continued in the homecare setting. From a preclinical point of view, defined stem cell transplantation approaches allow for the first time robust structural repair of the injured spinal cord. CONCLUSION Besides well-established neurological and functional scores, MRI techniques offer the unique opportunity to provide robust and reliable "biomarkers" for restorative therapeutic interventions. Function-oriented robotics-based rehabilitative interventions alone or in combination with stem cell based therapies represent promising approaches to achieve substantial functional recovery, which go beyond current rehabilitative treatment efforts.
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Affiliation(s)
- R Rupp
- Klinik für Paraplegiologie - Querschnittzentrum, Universitätsklinikum Heidelberg, Schlierbacher Landstr. 200a, 69118, Heidelberg, Deutschland
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Weisser G, Sauter E, Zöllner F, Weipert M, Schönberg SO, Schad L. UMMDiffusion: Eine OpenSource Software zur klinischen Evaluation der Kurtosis Bildgebung. ROFO-FORTSCHR RONTG 2014. [DOI: 10.1055/s-0034-1372714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Lassel EA, Daab M, Schülein P, Drechsler J, Schönberg SO, Schad L, Zöllner F, Weisser G. In-Haus-MPG-Zertifizierung von Software in der Radiologie am Beispiel von UMMPerfusion. ROFO-FORTSCHR RONTG 2013. [DOI: 10.1055/s-0033-1346267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Henzler T, Konstandin S, Schmid-Bindert G, Apfaltrer P, Haneder S, Wenz F, Schad L, Manegold C, Schoenberg S, Fink C. Imaging of Tumor Viability in Lung Cancer: Initial Results Using 23Na-MRI. ROFO-FORTSCHR RONTG 2012; 184:340-4. [DOI: 10.1055/s-0031-1299277] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- T. Henzler
- Institut of Clinical Radiology and Nuclear Medicine, University medical Center Mannheim, Medical Faculty Heidelberg University
| | - S. Konstandin
- Computer Assisted Clinical Medicine, Heidelberg University, Medical Faculty Mannheim
| | - G. Schmid-Bindert
- University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University, Interdisciplinary Thoracic Oncology, Department of Surgery
| | - P. Apfaltrer
- Institut of Clinical Radiology and Nuclear Medicine Mannheim, Germany, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University
| | - S. Haneder
- Institut of Clinical Radiology and Nuclear Medicine Mannheim, Germany, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University
| | - F. Wenz
- Department of Radiation Oncology, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University
| | - L. Schad
- Computer Assisted Clinical Medicine Mannheim, Germany, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University
| | - C. Manegold
- Interdisciplinary Thoracic Oncology, Department of Surgery, University Medical Center Mannheim, Medical Faculty Mannheim, Heidelberg University
| | - S. Schoenberg
- Institute of Clinical Radiology and Nuclear Medicine, University Medical Center Mannheim
| | - C. Fink
- Institut für Klinische Radiologie und Nuklearmedizin, Universitätsmedizin Mannheim, Universität Heidelberg
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Boda-Heggemann J, Haneder S, Konstandin S, Schad L, Wenz F, Michaely H, Lohr F. Assessment of 3D-conformal Radiotherapy (3DCRT) and Image-guided Intensity Modulated Radiotherapy (IG-IMRT) Induced Renal Damage by Means of Functional MR-imaging and 23Na-MR-imaging. Int J Radiat Oncol Biol Phys 2011. [DOI: 10.1016/j.ijrobp.2011.06.534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Zhang Y, Schuff N, Jahng GH, Bayne W, Mori S, Schad L, Mueller S, Du AT, Kramer JH, Yaffe K, Chui H, Jagust WJ, Miller BL, Weiner MW. Diffusion tensor imaging of cingulum fibers in mild cognitive impairment and Alzheimer disease. Neurology 2007; 68:13-9. [PMID: 17200485 PMCID: PMC1941719 DOI: 10.1212/01.wnl.0000250326.77323.01] [Citation(s) in RCA: 368] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Neuroimaging in mild cognitive impairment (MCI) and Alzheimer disease (AD) generally shows medial temporal lobe atrophy and diminished glucose metabolism and cerebral blood flow in the posterior cingulate gyrus. However, it is unclear whether these abnormalities also impact the cingulum fibers, which connect the medial temporal lobe and the posterior cingulate regions. OBJECTIVE To use diffusion tensor imaging (DTI), by measuring fractional anisotropy (FA), to test 1) if MCI and AD are associated with DTI abnormalities in the parahippocampal and posterior cingulate regions of the cingulum fibers; 2) if white matter abnormalities extend to the neocortical fiber connections in the corpus callosum (CC); 3) if DTI improves accuracy to separate AD and MCI from healthy aging vs structural MRI. METHODS DTI and structural MRI were preformed on 17 patients with AD, 17 with MCI, and 18 cognitively normal (CN) subjects. RESULTS FA of the cingulum fibers was significantly reduced in MCI, and even more in AD. FA was also significantly reduced in the splenium of the CC in AD, but not in MCI. Adding DTI to hippocampal volume significantly improved the accuracy to separate MCI and AD from CN. CONCLUSION Assessment of the cingulum fibers using diffusion tensor imaging may aid early diagnosis of Alzheimer disease.
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Affiliation(s)
- Y Zhang
- MR Unit (114M), VA Medical Center, 4150, Clement Street, San Francisco, CA 94121, USA.
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Huttner HB, Nielles-Vallespin S, Meinck HM, Schad L, Wöhrle J, Essig M, Weber MA. 23Na-Magnetresonanztomographie (MRT) bei Patienten mit Paramyotonia congenita (Eulenburg). Akt Neurol 2004. [DOI: 10.1055/s-2004-833427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Abstract
PURPOSE The purpose of this study was to evaluate the diagnostic potential of a high resolution MR venography technique in patients with cerebral arteriovenous malformations (AVM). A high-resolution 3D gradient echo sequence was used with a long echo time TE to obtain venous information down to sub-pixel sized vessel diameters of several hundred microns. The method is based on the paramagnetic property of deoxyhemoglobin and the resulting developing phase difference between veins and brain parenchyma at long echo times which leads to signal cancellation. The reconstructed venograms were compared with TOF-MR angiography using qualitative and quantitative criteria with the conventional DSA serving as the reference gold standard. METHODS In 17 patients with angiographically proven cerebral AVM the method indicates its potential in clinical applications. Venography was able to detect all AVM whereas TOF-MRA failed in three patients. In the delineation of venous drainage patterns MR venography was superior to TOF-MRA, however, as expected the method detected only about half of the main feeding arteries. Due to susceptibility artifacts at air/tissue boundaries or interference with paramagnetic hemosiderin, MR venography was limited with respect to the delineation of the exact nidus sizes and shapes in ten patients with AVM located close to the skull base or in patients having suffered from previous bleeding. RESULTS Although the visualization of draining veins represents an important prerequisite in the surgical and radiosurgical treatment planning of cerebral AVM, there exist limitations of the technique in regions where strong induced static field inhomogeneities are present. CONCLUSIONS Due to its high sensitivity the method may be of special importance in the early detection and assessment of small AVM which are difficult to diagnose with other MR methods.
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Affiliation(s)
- M Essig
- Forschungsschwerpunkt Radiologische Diagnostik und Therapie, Deutsches Krebsforschungszentrum, Im Neuenheimer Feld 280, 69120 Heidelberg.
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Debus J, Schulz-Ertner D, Schad L, Essig M, Rhein B, Thillmann CO, Wannenmacher M. Stereotactic fractionated radiotherapy for chordomas and chondrosarcomas of the skull base. Int J Radiat Oncol Biol Phys 2000; 47:591-6. [PMID: 10837940 DOI: 10.1016/s0360-3016(00)00464-8] [Citation(s) in RCA: 211] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE To investigate the treatment outcome of patients suffering from skull base chordoma or chondrosarcoma after fractionated stereotactic radiotherapy. METHODS AND MATERIALS We report 45 patients treated for chordoma or chondrosarcoma with postoperative fractionated stereotactic radiotherapy between 1990 and 1997. Patients had CT and MRI for 3D treatment planning performed under stereotactic guidance. Median dose at isocenter was 66.6 Gy for chordomas and 64.9 Gy for chondrosarcomas. MRI imaging was obtained in intervals after therapy to evaluate local relapse. Survival was calculated according to the Kaplan-Meier method. RESULTS All chondrosarcomas had achieved and maintained local control and recurrence-free status at follow-up of 5 years. Local control rate of chordomas was 82% at 2 years and 50% at 5 years. Survival was 97% at 2 years and 82% at 5 years. At maximum follow-up of 8 years local control and survival rate of chordomas was 40% (82%). Clinically significant late toxicity developed in one patient. CONCLUSIONS Our results demonstrate the feasibility of fractionated photon beam therapy and its success in the treatment of skull base tumors. Modern 3D treatment techniques provide superior results compared to conventional techniques. The role of high-precision radiotherapy compared to particle beam therapy in the treatment of these tumors is not yet fully clear and further research is needed.
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Affiliation(s)
- J Debus
- Department of Clinical Radiology, University of Heidelberg, Germany.
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Schoenberg SO, Knopp MV, Bock M, Kallinowski F, Just A, Essig M, Hawighorst H, Zuna I, Schad L, Allenberg JR, van Kaick G. [Classification of hemodynamic changes in renal artery stenosis using cine magnetic resonance phase contrast flow measurements]. Radiologe 1997; 37:651-62. [PMID: 9411483 DOI: 10.1007/s001170050267] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
PURPOSE To evaluate the use of high-temporal resolution cine MR phase-contrast flow measurements for assessment of flow dynamics in renal artery stenosis (RAS). MATERIAL AND METHODS In a dog model, cine MR flow measurements were validated by comparing the MR flow data to an invasive transit-time ultrasound reference technique for different degrees of RAS. Cardiac-gated MR flow curves were recorded in 56 renal arteries of 28 patients with a temporal resolution of at least 32 ms. In all cases RAS was confirmed by digital subtraction angiography (DSA). Abnormalities of flow dynamics were assessed in the calculated flow curves using the MR parameters mean flow, maximum velocity, and time to systolic maximum. RESULTS By means of the MR blood flow parameters high-grade stenoses (> 50%, n = 23) were detected with sensitivity of 100% and specificity of 94% with reference to DSA. The overall differentiation between stenoses (n = 37) and non-stenosed vessels (n = 19) revealed a sensitivity of 87% and a specificity of 100%. CONCLUSION Analysis of cardiac-gated MR flow curves provides a non-invasive method to assess the hemodynamic significance of RAS and thus allows a functional evaluation in relation to the morphologic characteristics of the stenosis.
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Affiliation(s)
- S O Schoenberg
- Deutsches Krebsforschungszentrum (DKFZ), Abteilung Radiologische Diagnostik und Therapie, Heidelberg
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Schoenberg SO, Knopp MV, Bock M, Kallinowski F, Just A, Essig M, Hawighorst H, Schad L, van Kaick G. Renal artery stenosis: grading of hemodynamic changes with cine phase-contrast MR blood flow measurements. Radiology 1997; 203:45-53. [PMID: 9122415 DOI: 10.1148/radiology.203.1.9122415] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
PURPOSE To analyze the blood flow dynamics in renal artery stenosis with high-temporal-resolution cine phase-contrast magnetic resonance (MR) flow measurements. MATERIALS AND METHODS Cine phase-contrast MR flow measurements were invasively validated with real-time intraoperative transit-time ultrasound (US). In 23 patients, 48 renal artery stenoses were confirmed at digital subtraction angiography. Cardiac-gated cine phase-contrast MR flow measurements were obtained in 32-msec intervals, and flow curves were calculated for the whole cardiac cycle. Hemodynamic parameters evaluated included the decrease in mean flow and the delay and reduction in the systolic velocity maximum due to decrease in or absence of the early systolic peak. RESULTS Overall differentiation between renal artery stenosis (n = 31) and nonstenosed vessels (n = 17) with cine phase-contrast MR revealed a sensitivity of 90% and specificity of 94% compared with findings at digital subtraction angiography. High-grade stenoses (>50%, n = 19) were detected with cine phase-contrast MR with sensitivity of 100% and specificity of 93%. CONCLUSION Quantitative and qualitative analysis of cardiac-gated cine phase-contrast MR flow velocity curves provided a highly accurate method to detect hemodynamic abnormalities in patients with suspected renal artery stenosis.
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Affiliation(s)
- S O Schoenberg
- Department of Radiology, German Cancer Research Center, Heidelberg
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Abstract
We report our preliminary results using a new magnetic resonance imaging technique for visualization of the urinary tract. Using the paramagnetic contrast medium gadolinium diethylene triamine penta-acetic acid (DTPA), we were able to obtain images of the urinary tract comparable to those obtained by conventional excretory urography. The major advantage of our technique is that besides good morphologic visualization, the excretion of gadolinium-DTPA can be studied simultaneously. We demonstrate our preliminary results in selected cases.
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Affiliation(s)
- J Dörsam
- Abteilung Urologie und Poliklinik, Universität Heidelberg
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Dörsam J, Knopp MV, Carl S, Oesingmann N, Schad L, Brkovic D, van Kaick G, Staehler G. Ureteral complications after kidney transplantation--evaluation with functional magnetic resonance urography. Transplant Proc 1997; 29:132-5. [PMID: 9122928 DOI: 10.1016/s0041-1345(96)00035-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J Dörsam
- Department of Urology, University of Heidelberg, Germany
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Gerdsen I, Frost S, Schröder J, Essig M, Baudendistel K, Schad L. Evidence for medial temporal lobe changes in schizophrenia: A quantitative MRI study. Eur Psychiatry 1996. [DOI: 10.1016/0924-9338(96)89342-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Affiliation(s)
- J. Dörsam
- Department of Urology, University of Heidelberg Heidelberg, Germany
| | - M. V. Knopp
- German Cancer Research Center (DKFZ) Heidelberg, Germany
| | - L. Schad
- German Cancer Research Center (DKFZ) Heidelberg, Germany
| | - S. Piesche
- German Cancer Research Center (DKFZ) Heidelberg, Germany
| | - S. Carl
- Department of Urology, University of Heidelberg Heidelberg, Germany
| | - N. Oesingmann
- German Cancer Research Center (DKFZ) Heidelberg, Germany
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Debus J, Engenhart R, Rhein B, Schlegel W, Schad L, Pastyr O, Wannenmacher M. Clinical application of conformal radiosurgery using multileaf-collimators. Int J Radiat Oncol Biol Phys 1994. [DOI: 10.1016/0360-3016(94)90819-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Gademann G, Schlegel W, Debus J, Schad L, Bortfeld T, Höver KH, Lorenz WJ, Wannenmacher M. Fractionated stereotactically guided radiotherapy of head and neck tumors: a report on clinical use of a new system in 195 cases. Radiother Oncol 1993; 29:205-13. [PMID: 8310147 DOI: 10.1016/0167-8140(93)90248-7] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Between November 1988 and December 1992, 195 patients with tumors of the head and neck (low grade gliomas, meningiomas, neurinomas, chordomas and miscellaneous) were treated with a newly developed stereotactical system for fractionated, conformal, high-precision radiotherapy. The overall preparation time, including head mask production for fixation, CT, MRI, 3-D treatment planning and stereotactical localisation could be reduced to 4-5 h per patient. The use of MR in the target definition was increased to a mean of about 60%. The medial follow-up time is 22 months. Three different patient groups were selected according to pretreatment. Patients with full high-precision radiotherapy survived in 95% of cases, patients with boost treatment in 86% and patients with preirradiated recurrent disease in 64%. Meningiomas as the largest histology group (n = 62) showed partial response in 27% and complete response in 10% of cases. Progression occurred in two patients. All patients are alive. Acute side-effects were minimal and of the order of 10%, no late complications occurred despite tumor doses ranging up to 72 Gy. High-precision radiotherapy as it is performed in Heidelberg can be regarded as an effective, reliable and tolerable system for selected tumors of the head and neck.
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Affiliation(s)
- G Gademann
- Radiotherapy Department, University of Heidelberg, Germany
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Schlegel W, Pastyr O, Bortfeld T, Becker G, Schad L, Gademann G, Lorenz WJ. Computer systems and mechanical tools for stereotactically guided conformation therapy with linear accelerators. Int J Radiat Oncol Biol Phys 1992; 24:781-7. [PMID: 1429105 DOI: 10.1016/0360-3016(92)90729-2] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
An integrated system for fractionated, stereotactically guided conformation radiotherapy has been developed. The system components are a stereotactic fixation system that can be used each treatment day, a localization, and positioning unit that can be used during x-ray computer tomography, magnetic resonance imaging, positron emission tomography, and radiographical examinations as well as for treatment. Conformal precision radiotherapy is planned with a new three-dimensional treatment planning system (Voxel-Plan-Heidelberg) which comprises, among others options, a three-dimensional image correlation procedure as well as routines for the calculation of coplanar and non-coplanar irradiations with irregularly shaped fields. Two different multi-leaf collimators have been designed for precision radiotherapy in the head and neck region. A manual multi-leaf collimator is used for irradiations with stationary beams or for moving beam treatments with invariable irregularly shaped fields. This collimator system is now being used for patient treatments. The design of a computer controlled multi-leaf collimator unit for multiple fixed field irradiation techniques is discussed. All system components are aimed at conforming dose distributions for fractionated radiotherapy treatments to the target to improve sparing of adjacent normal tissues, and at achieving a sufficient geometrical accuracy in the dose application.
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Affiliation(s)
- W Schlegel
- Institute of Radiology and Pathophysiology, German Cancer Research Center, Heidelberg
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Schlegel W, Pastyr O, Boesecke R, Bortfeld T, Schad L, Gademann G, Lorenz W. Computer systems and mechanical tools for stereotactically guided conformation therapy with linear accelerators. Int J Radiat Oncol Biol Phys 1990. [DOI: 10.1016/0360-3016(90)90670-f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Schad L, Lott S, Schmitt F, Sturm V, Lorenz WJ. Correction of spatial distortion in MR imaging: a prerequisite for accurate stereotaxy. J Comput Assist Tomogr 1987; 11:499-505. [PMID: 3553251 DOI: 10.1097/00004728-198705000-00025] [Citation(s) in RCA: 92] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
With magnetic resonance (MR) imaging, accurate spatial information--critical for effective stereotaxy--demands a homogeneous static field and linear gradients. Inhomogeneities and nonlinearities induced by eddy currents during the pulse sequences distort the images and produce spurious displacements of the stereotactic coordinates in both the x-y plane and the z axis. These errors in position can be assessed by means of two phantoms placed within the stereotactic guidance system--a "two-dimensional phantom" displaying "pincushion" distortion in the image (i.e., x, y) plane, and the "three-dimensional phantom" displaying displacement, warp, and tilt of the image plane itself. The pincushion distortion can be "corrected" (reducing displacements from 5 to 1-2 mm) by calculations based on modeling the distortion as a fourth order two-dimensional polynomial. Based on these corrected images, errors in the z coordinate and tilt of image planes may be corrected by adjustment of the gradient shimming currents. Such correction not only implements stereotaxy under MR guidance but also provides for the accurate transfer of anatomic/pathologic information between MR and CT images.
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Schad L. Ueber einige aus Brucin und Bromäthylen entstehende Verbindungen. European J Org Chem 1861. [DOI: 10.1002/jlac.18611180207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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