Kooperativer Bibliotheksverbund

Language: English

In: Radiotherapy and Oncology, Dec, 2004, Vol.73, p.S99-S101

Description: Byline: Ulla Ramm ((a)), Jussi Moog ((a)), Belinda Spielberger ((b)), Achim Bankamp ((c)), Heinz-Dietrich Bottcher ((a)), Gerhard Kraft ((b)) Abstract: In this presentation BANG[R] polymer-gel dosimetry using magnetic resonance imaging (MRI) is applied to densely ionizing radiation such as carbon ion beams. BANG[R] polymer-gels were irradiated with monoenergetic.sup.12C ions at an energy of 205 MeVu.sup.-1. The irradiation of the gels with doses up to 100 Gy were performed at the radiotherapy facility of the GSI, Darmstadt, Germany. For comparison with sparsely ionizing radiation data were obtained for 6 MV photon radiation, too. It was the object to examine the saturation effect for densely ionizing radiation that occurs at high values of linear energy transfer (LET). Up to now the dose response is unknown for mixed radiation fields of primary carbon ions. Therefore, to facilitate such conversions of measured MR signals into dose model calculations are proposed. This model relies only on heavy ion track structure and the experimentally determined photon response. Author Affiliation: ((a)) Universitatsklinikum, Klinik f. Strahlentherapie, 60590 Frankfurt/Main, Germany ((b)) Gesellschaft f. Schwerionenforschung (GSI), 64291 Darmstadt, Germany ((c)) Deutsches Krebsforschungszentrum (DKFZ), 69120 Heidelberg, Germany

Keywords: Radiation (Physics) -- Investigations

ISSN: 0167-8140

Source: Cengage Learning, Inc.

Language: English

In: Strahlentherapie und Onkologie, August, 2009, Vol.185(2), p.530(7)

Description: Byline: Christian Scherf (1,3), Christiane Peter (1,2), Jussi Moog (1), Jorg Licher (1), Eugen Kara (1), Klemens Zink (2), Claus Rodel (1), Ulla Ramm (1) Keywords: Dosimetry diode; Diamond detector; Water phantom; Depth dose curve; Lateral dose profile; Dosimetriediode; Diamantsonde; Wasserphantom; Tiefendosiskurve; Dosisquerprofil Abstract: Background: Depth dose curves and lateral dose profiles should correspond to relative dose to water in any measured point, what can be more or less satisfied with different detectors. Diamond as detector material has similar dosimetric properties like water. Silicon diodes and ionization chambers are also commonly used to acquire dose profiles. Material and Methods: The authors compared dose profiles measured in an MP3 water phantom with a diamond detector 60003, unshielded and shielded silicon diodes 60008 and 60012 and a 0.125-cm.sup.3 thimble chamber 233642 (PTW, Freiburg, Germany) for 6- and 25-MV photons. Electron beams of 6, 12 and 18 MeV were investigated with the diamond detector, the unshielded diode and a Markus chamber 23343. Results: The unshielded diode revealed relative dose differences at the water surface below +10% for 6-MV and +4% for 25-MV photons compared to the diamond data. These values decreased to less than 1% within the first millimeters of water depth. The shielded diode was only required to obtain correct data of the fall-off zones for photon beams larger than 10 x 10 cm.sup.2 because of important contributions of low-energy scattered photons. For electron radiation the largest relative dose difference of --2% was observed with the unshielded silicon diode for 6 MeV within the build-up zone. Spatial resolutions were always best with the small voluminous silicon diodes. Conclusion: Relative dose profiles obtained with the two silicon diodes have the same degree of accuracy as with the diamond detector. Abstract (German): Hintergrund: Tiefendosiskurven und Dosisquerprofile sollten in allen Messpunkten der relativen Wasserenergiedosis entsprechen, was mit verschiedenen Messsonden mehr oder weniger gut erreicht wird. Diamantsonden verhalten sich dosimetrisch fast wasseraquivalent. P-Typ-Siliciumdioden und Ionisationskammern werden ebenfalls haufig zur Messung von Dosisprofilen genutzt. Material und Methodik: In einem MP3-Wasserphantom wurden gemessene Tiefendosiskurven und Dosisquerprofile einer Diamantsonde 60003, je einer ungekapselten und einer gekapselten Si-Diode 60012 und 60008 und einer 0,125-cm.sup.3-Schlauchkammer 233642 (alle von PTW, Freiburg) fur 6- und 25-MV-Photonenstrahlung verglichen. Elektronenfelder (6, 12 und 18 MeV) wurden mit der Diamantsonde, der ungekapselten Diode und einer Markus-Kammer 23343 untersucht. Ergebnisse: Bei Photonenstrahlung konnte fur die ungekapselte Diode an der Wasseroberflache eine Abweichung der relativen Tiefendosis im Vergleich zur Diamantsonde kleiner +10% bei 6 MV und kleiner +4% bei 25 MV festgestellt werden. Diese Abweichungen sanken bereits in einigen Millimetern Wassertiefe auf unter 1% ab. Die gekapselte Diode war ausschliesslich fur die korrekte Messung der abfallenden Bereiche von Tiefendosiskurven bei Feldern uber 10 x 10 cm.sup.2 erforderlich, da die hier hohen Beitrage der niederenergetischen Streustrahlungsphotonen von Silicium uberproportional stark absorbiert und registriert werden. Die maximal gemessene Abweichung der relativen Tiefendosis mit der ungekapselten Diode bei Elektronenstrahlung betrug --2% innerhalb der Aufbauzone bei 6 MeV. Bei allen untersuchten Strahlenarten ubertraf das raumliche Auflosungsvermogen der kleinvolumigen Dioden das der Diamantsonde. Schlussfolgerung: Mit den beiden Dioden gemessene relative Dosisprofile sind vergleichbar genau wie die mit der Diamantsonde gemessenen. Author Affiliation: (1) Department of Radiotherapy and Oncology, Center of Radiology, University Hospital, Johann Wolfgang Goethe University Frankfurt/Main, Frankfurt/Main, Germany (2) Institute for Medical Physics and Radiation Protection, KMUB Faculty, Advanced Technical College Giessen-Friedberg, Frankfurt/Main, Germany (3) Klinik fur Strahlentherapie und Onkologie, Medizinische Physik, Goethe-Universitat Frankfurt/Main, Theodor-Stern-Kai 7, 60590, Frankfurt/Main, Germany Article History: Registration Date: 01/01/2009 Received Date: 17/02/2009 Accepted Date: 05/03/2009 Online Date: 04/08/2009

Keywords: Silicon -- Measurement ; Ghosts -- Measurement ; Ionization -- Measurement ; Universities And Colleges -- Measurement ; Detection Equipment -- Measurement

ISSN: 0179-7158

Source: Cengage Learning, Inc.

Language: English

In: Strahlentherapie und Onkologie, 2008, Vol.184(7), pp.376-380

Description: Byline: Ulla Ramm (1,3), Jorg Licher (1), Jussi Moog (1), Christian Scherf (1), Eugen Kara (1), Heinz-Dietrich Bottcher (1), Claus Rodel (1), Stephan Mose (1,2) Keywords: Total-body irradiation; In vivo dosimetry; Semiconductor detectors; Ganzkorperbestrahlung; In-vivo-Dosimetrie; Halbleiters Abstract: Background and Purpose: For total-body irradiation (TBI) using the translation method, dose distribution cannot be computed with computer-assisted three-dimensional planning systems. Therefore, dose distribution has to be primarily estimated based on CT scans (beam-zone method) which is followed by in vivo measurements to ascertain a homogeneous dose delivery. The aim of this study was to clinically establish semiconductor probes as a simple and fast method to obtain an online verification of the dose at relevant points. Patients and Methods: In 110 consecutively irradiated TBI patients (12.6 Gy, 2 x 1.8 Gy/day), six semiconductor probes were attached to the body surface at dose-relevant points (eye/head, neck, lung, navel). The mid-body point of the abdomen was defined as dose reference point. The speed of translation was optimized to definitively reach the prescribed dose in this point. Based on the entrance and exit doses, the mid-body doses at the other points were computed. The dose homogeneity in the entire target volume was determined comparing all measured data with the dose at the reference point. Results: After calibration of the semiconductor probes under treatment conditions the dose in selected points and the dose homogeneity in the target volume could be quantitatively specified. In the TBI patients, conformity of calculated and measured doses in the given points was achieved with small deviations of adequate accuracy. The data of 80% of the patients are within an uncertainty of +- 5%. Conclusion: During TBI using the translation method, dose distribution and dose homogeneity can be easily controlled in selected points by means of semiconductor probes. Semiconductor probes are recommended for further use in the physical evaluation of TBI. Abstract (German): Hintergrund und Ziel: Die Dosisverteilung bei Ganzkorperbestrahlung (TBI) mit Translationstechnik lasst sich in der klinischen Routine bisher nicht mit computergestutzten dreidimensionalen Planungssystemen berechnen. Die notwendige Kontrolle der auf der Basis von CT-Daten mit Hilfe von Abschatzverfahren manuell berechneten Dosisverteilung (Feldzonenverfahren) lasst sich nur mittels In-vivo-Messungen durchfuhren, um eine homogene Dosisverteilung abzusichern. Ziel dieser Studie war es, Halbleitersonden als eine einfache und schnelle Methode zu etablieren, um eine Onlineverifikation an relevanten Punkten zu ermoglichen. Patienten und Methodik: Bei 110 konsekutiv bestrahlten TBI-Patienten (12,6 Gy, 2 x 1,8 Gy/Tag) wurden sechs Halbleitersonden an dosisrelevanten Punkten der Korperoberflache (Auge/Kopf, Hals, Lunge, Bauchnabel) befestigt. Der Punkt in der Abdomenmitte wurde als Dosisreferenzpunkt definiert. Die Translationsgeschwindigkeit wurde derart optimiert, dass an diesem Punkt die vorgeschriebene Herddosis erreicht wurde. Basierend auf der Eintritts- und Austrittsdosis an den jeweils anderen Punkten wurde die Dosis in der dortigen Korpermitte berechnet. Die Dosishomogenitat im gesamten Zielvolumen wurde durch den Vergleich der einzelnen Messwerte mit der Dosis am Referenzpunkt ermittelt. Ergebnisse: Nach Kalibrierung der Halbleitersonden unter Bestrahlungsbedingungen konnten die Dosis in ausgewahlten Punkten und die Dosishomogenitat im Zielvolumen quantitativ angegeben werden. Dosismessungen wahrend der TBI zeigten eine Ubereinstimmung der erwarteten und der gemessenen Dosis mit Abweichungen in den untersuchten Punkten mit hinreichender Genauigkeit. Die Daten zeigen fur 80% der Patienten eine Unsicherheit von weniger als +- 5%. Schlussfolgerung: Mit Halbleitersonden konnen in der klinischen Routine mit geringem Aufwand die Dosis wahrend der Translations-TBI in ausgewahlten Punkten gemessen und die Dosishomogenitat im Zielvolumen uberpruft werden. Daher bieten sich Halbleitersonden fur die physikalische Uberprufung der TBI an. Author Affiliation: (1) Department of Radiotherapy and Oncology, Center of Radiology, University Hospital, Johann Wolfgang Goethe University, Frankfurt/Main, Germany (2) Department of Radiotherapy and Radiooncology, Schwarzwald-Baar Hospital, Villingen-Schwenningen, Germany (3) Klinik fur Strahlentherapie und Onkologie, Medizinische Physik, Johann Wolfgang Goethe-Universitat, Theodor-Stern-Kai 7, 60590, Frankfurt, Germany Article History: Registration Date: 01/01/2008 Received Date: 17/10/2007 Accepted Date: 26/03/2008 Online Date: 01/10/2008

Keywords: Total-body irradiation ; In vivo dosimetry ; Semiconductor detectors

ISSN: 0179-7158

E-ISSN: 1439-099X

DOI: 10.1007/s00066-008-1823-5

URL: View full text in Springer (Subscribers only)

Language: English

In: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology, December 2004, Vol.73 Suppl 2, pp.S99-101

Description: In this presentation BANG polymer-gel dosimetry using magnetic resonance imaging (MRI) is applied to densely ionizing radiation such as carbon ion beams. BANG polymer-gels were irradiated with monoenergetic 12C ions at an energy of 205 MeVu(-1). The irradiation of the gels with doses up to 100 Gy were performed at the radiotherapy facility of the GSI, Darmstadt, Germany. For comparison with sparsely ionizing radiation data were obtained for 6 MV photon radiation, too. It was the object to examine the saturation effect for densely ionizing radiation that occurs at high values of linear energy transfer (LET). Up to now the dose response is unknown for mixed radiation fields of primary carbon ions. Therefore, to facilitate such conversions of measured MR signals into dose model calculations are proposed. This model relies only on heavy ion track structure and the experimentally determined photon response.

Keywords: Gels ; Heavy Ion Radiotherapy ; Polymers ; Carbon -- Therapeutic Use

ISSN: 0167-8140

Source: MEDLINE/PubMed (U.S. National Library of Medicine)

URL: View this record in MEDLINE/PubMed

Language: English

In: Radiotherapy and Oncology, 2004, Vol.73, pp.S99-S101

Description: In this presentation BANG® polymer-gel dosimetry using magnetic resonance imaging (MRI) is applied to densely ionizing radiation such as carbon ion beams. BANG® polymer-gels were irradiated with monoenergetic C ions at an energy of 205 MeVu . The irradiation of the gels with doses up to 100 Gy were performed at the radiotherapy facility of the GSI, Darmstadt, Germany. For comparison with sparsely ionizing radiation data were obtained for 6 MV photon radiation, too. It was the object to examine the saturation effect for densely ionizing radiation that occurs at high values of linear energy transfer (LET). Up to now the dose response is unknown for mixed radiation fields of primary carbon ions. Therefore, to facilitate such conversions of measured MR signals into dose model calculations are proposed. This model relies only on heavy ion track structure and the experimentally determined photon response.

Keywords: Heavy Ion ; Dosimetry ; Dose Verification ; Polymer Gels ; Medicine

ISSN: 0167-8140

E-ISSN: 1879-0887

DOI: 10.1016/S0167-8140(04)80025-2

URL: View record in ScienceDirect (Access to full text may be restricted)

Language: English

In: Strahlentherapie und Onkologie, 2009, Vol.185(8), pp.530-536

Description: Depth dose curves and lateral dose profiles should correspond to relative dose to water in any measured point, what can be more or less satisfied with different detectors. Diamond as detector material has similar dosimetric properties like water. Silicon diodes and ionization chambers are also commonly used to acquire dose profiles. The authors compared dose profiles measured in an MP3 water phantom with a diamond detector 60003, unshielded and shielded silicon diodes 60008 and 60012 and a 0.125-cm(3) thimble chamber 233642 (PTW, Freiburg, Germany) for 6- and 25-MV photons. Electron beams of 6, 12 and 18 MeV were investigated with the diamond detector, the unshielded diode and a Markus chamber 23343. The unshielded diode revealed relative dose differences at the water surface below +10% for 6-MV and +4% for 25-MV photons compared to the diamond data. These values decreased to less than 1% within the first millimeters of water depth. The shielded diode was only required to obtain correct data of the fall-off zones for photon beams larger than 10 x 10 cm(2) because of important contributions of low-energy scattered photons. For electron radiation the largest relative dose difference of -2% was observed with the unshielded silicon diode for 6 MeV within the build-up zone. Spatial resolutions were always best with the small voluminous silicon diodes. Relative dose profiles obtained with the two silicon diodes have the same degree of accuracy as with the diamond detector.

Keywords: Dosimetry diode ; Diamond detector ; Water phantom ; Depth dose curve ; Lateral dose profile

ISSN: 0179-7158

E-ISSN: 1439-099X

DOI: 10.1007/s00066-009-2004-x

URL: View full text in Springer (Subscribers only)

Language: English

In: International Journal of Oncology, October 2005, Vol.27(4), pp.1029-1037

Description: Acquisition of P-gp-mediated multidrug-resistance does not always correlate with observed malignant behavior of NB. To characterize alterations accompanying development of multidrug-resistance in NB we established two neuroblastoma cell sublines resistant to vincristine (UKF-NB-3rVCR10) and doxorubicin (UKF-NB-3rDOX20). UKF-NB-3rVCR10 and UKF-NB-3rDOX20 overexpressed functional P-gp and developed an increased malignant phenotype: presented constitutive phosphorylation of AKT, resistance to γ-irradiation, and had increased survival in serum-free medium. Inhibition of P-gp restored chemosensitivity but did not affect increased survival in serum-free medium and sensitivity to γ-irradiation. Inhibition of AKT had no influence on chemoresistance but restored sensitivity to serum starvation. Both resistant cell lines acquired additional chromosomal changes. UKF-NB-3rVCR10 cells acquired a missense P53 mutation in exon 5, an increased MYCN amplification, an enhanced adhesion to endothelium, a decreased NCAM expression, a distinctly higher clonogenicity, and an increased in vivo tumorigenicity. We conclude that acquisition of increased malignant behavior in neuroblastoma occurs concomitantly with multidrug-resistance and is P-gp-independent.

Keywords: Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; ATP Binding Cassette Transporter, Subfamily B, Member 1 -- Metabolism ; Neuroblastoma -- Pathology;

ISSN: 1019-6439

E-ISSN: 17912423

URL: View this record in Spandidos Publications

In: International Journal of Oncology, 10/01/2005

ISSN: 1019-6439

E-ISSN: 1791-2423

DOI: 10.3892/ijo.27.4.1029

Source: CrossRef