Dynamic determination of equivalent CT source models for personalized dosimetry

With improvements in CT technology, the need for reliable patient-specific dosimetry increased in the recent years. The accuracy of Monte-Carlo simulations for absolute dose estimation is related to scanner specific information on the X-ray spectra of the scanner as well as the form filter geometries and compositions. In this work a mobile measurement setup is developed, which allows both to determine the X-ray spectra and equivalent form filter of a specific scanner from just one helical scan in less than 2 minutes

First international comparison of primary absorbed dose to water standards in the medium-energy X-ray range

International audienceThis report presents the results of the first international comparison of primary measurement standards of absorbed dose to water for the medium-energy X-ray range. Three of the participants (VSL, PTB, LNE-LNHB) used their existing water calorimeter based standards and one participant (ENEA) recently developed a new standard based on a water-graphite calorimeter. The participants calibrated three transfer chambers of the same type in terms of absorbed dose to water (NDw) and in addition in terms of air kerma (NK) using the CCRI radiation qualities in the range 100 kV to 250 kV. The additional NK values were intended to be used for a physical analysis of the ratios NDw/NK.All participants had previously participated in the BIPM.RI(I)-K3 key comparison of air kerma standards. Ratios of pairs of NMI's NK results of the current comparison were found to be consistent with the corresponding key comparison results within the expanded uncertainties of 0.6 % - 1 %. The NDw results were analysed in terms of the degrees of equivalence with the comparison reference values which were calculated for each beam quality as the weighted means of all results. The participant's results were consistent with the reference value within the expanded uncertainties. However, these expanded uncertainties varied significantly and ranged between about 1-1.8 % for the water calorimeter based standards and were estimated at 3.7 % for the water-graphite calorimeter.It was shown previously that the ratios NDw/NK for the type of ionization chamber used as transfer chamber in this comparison were very close (within less than 1 %) to the calculated values of (bar muen/ρ)w,ad, the mean values of the water-to-air ratio of the mass-energy-absorption coefficients at the depth d in water. Some of the participant's results deviated significantly from the expected behavior

Ionisierende Strahlung in der Medizin (Auszug aus: PTB-Mitteilungen 2013, Band 123, Heft 2. ISSN 0030-834X)

PTB-Mitteilungen. Band 123 (2013), Heft 2, Seite 1 - 81. ISSN 0030-834X1.: Janßen, Herbert: Vorwort 2.: Ankerhold, Ulrike: Ionisierende Strahlung in Diagnostik und Therapie 3.: Büermann, Ludwig: Metrologische Aspekte der Dosimetrie in der Röntgendiagnostik 4.: Kossert, Karsten: Aktivitätsbestimmung von Radionukliden für Diagnostik und Therapie 5.: Ankerhold, Ulrike und Thorsten Schneider: Dosimetrie für die Brachytherapie 6.: Krauss, Achim: Kalorimetrische Bestimmung der Wasser-Energiedosis 7.: Kapsch, Ralf-Peter: Dosimetrie mit Ionisationskammern in der externen Strahlentherapie 8.: Anton, Mathias: Dosimetrie für die externe Strahlentherapie: Dosimetrie mit Alanin 9.: Ambrosi, Peter: Strahlenschutz in der Medizin 10.: Hupe, Oliver: Messgeräte und Herausforderungen in der Strahlenschutzmesstechnik 11.: Ambrosi,Peter, Oliver Hupe und H.-M. Kramer: Messgrößen im Strahlenschutz 12.: Hupe, Oliver: Amtliche Personendosimetrie für Medizin-Personal 13.: Hupe, Oliver: Dosis für helfende Personen in der Human-, Zahn- und Tiermedizin 14: Behrens, Rolf: Teilkörperdosimetrie für Photonen und Betastrahlung 15.: Hupe, Oliver, Hayo Zutz und Peter Ambrosi: Elektronische Dosimeter für gepulste Strahlung 16.: Zutz, Hayo: Messung der Strahlung im Beschleuniger-Therapieraum 17.: Hans Rabus: Strahlenwirkung 18.: Arndt, Alexander und Woon Yong Baek: Strahlenwirkung auf Biomoleküle 19.: Bug, Marion und Heidi Nettelbeck: Simulation der Strahlenwirkung auf biologische Objekte 20.: Hilgers, Gerhard: Messung der Spurstruktur ionisierender Strahlung 21.: Giesen, Ulrich: Strahlenwirkung auf zellulärer Eben