«Ποσοτικοποίηση του κλινικού οφέλους της χρήσεως νέων προγραμμάτων σχεδιασμού βραχυθεραπείας του μαστού»

Η εργασία αυτή πραγματεύεται την ποσοτικοποίηση του κλινικού οφέλους της χρήσεως νέων προγραμμάτων σχεδιασμού βραχυθεραπείας του μαστού. Σκοπός είναι η σύγκριση δυο αλγορίθμων υπολογισμού της δόσης που απορροφάται από ασθενείς οι οποίοι υποβάλλονται σε βραχυθεραπεία. Ο ένας αλγόριθμος που τίθεται υπό σύγκριση είναι ο αλγόριθμος TG43 – AAPM (American Association of Physicists in Medicine) - ο οποίος βασίζεται σε υπέρθεση δεδομένων από Monte Carlo προσομοίωση κατά την οποία η εκάστοτε πηγή βραχυθεραπείας θεωρείται στο κέντρο ομογενούς ομοιώματος νερού. Συνεπώς αγνοείται η γεωμετρία του ασθενούς, και επομένως οι διαφορετικές συνθήκες σκέδασης που υπάρχουν σε μια πραγματική γεωμετρία, καθώς και η εγγενώς ανομοιογενής γεωμετρία του ασθενούς. Ο δεύτερος αλγόριθμος είναι ο TG186 – ACE (Advanced Collapsed cone Engine) - ο οποίος παράγει δεδομένα μέσω της μεθόδου υπέρθεσης/συνέλιξης Collapsed Cone, και έχει τη δυνατότητα να λαμβάνει υπόψιν του όλα τα παραπάνω. Η σύγκριση πραγματοποιήθηκε σε δείγμα 21 ασθενών οι οποίοι υπεβλήθησαν σε βραχυθεραπεία του μαστού με πηγή 192Ir. O αλγόριθμος TG43 βρέθηκε να υπερεκτιμά την απορροφούμενη δόση μακριά από την πηγή σε σημεία όπου υπερτερεί η δευτερογενής ακτινοβολία, καθώς και στις διεπιφάνειες ανατομικών δομών (παραδείγματος χάριν στους πνεύμονες) λόγω συνθηκών έλλειψης της οπισθοσκεδαζόμενης ακτινοβολίας. Ο δε αλγόριθμος TG186, παρουσιάζει υποεκτίμηση της απορροφούμενης δόσης κοντά στις πηγές. Επιπλέον, ο TG186 μεταβάλλει τη διακριτοποίηση του χώρου χρησιμοποιώντας μεγαλύτερα voxels σχετικά μακριά από τις θέσεις πηγών, προκειμένου να αυξήσει την ταχύτητα υπολογισμών. Αυτό έχει ως αποτέλεσμα την εμφάνιση συστηματικών σφαλμάτων ή τεχνουργημάτων στις κατανομές δόσης.This paper deals with the quantification of the clinical benefit of using new breast brachytherapy design programs. The purpose is to compare two dose calculation algorithms absorbed by patients undergoing brachytherapy. One algorithm to be compared is the TG43 - AAPM (American Association of Physicists in Medicine) algorithm - which is based on the Monte Carlo data overlay simulation in which each source of brachytherapy is considered in the homogeneous water model. Therefore, the geometry of the patient, and thus the different scattering conditions present in a real geometry, as well as the inherently heterogeneous geometry of the patient, are ignored. The second algorithm is the Advanced Collapsed Cone Engine (TG186) - which produces data through the Collapsed Cone overlay / convolution method, and has the ability to take into account all of the above. The comparison was performed on a sample of 21 patients who underwent breast brachytherapy with a 192Ir source. The TG43 algorithm was found to overestimate the absorbed dose away from the source at sites where secondary radiation prevails, as well as in the interfaces of anatomic structures (for example, lungs) due to lack of backscatched radiation. The TG186 algorithm shows underestimation of the absorbed dose near the sources. In addition, the TG186 modifies spatial discretization by using larger voxels relatively far from the source locations in order to increase the calculation speed. This results in systematic errors or artifacts in dose distributions

Status of the detector design studies for ESSν\nuSB

International audienceThe European Spallation Source Neutrino Super Beam (ESSnuSB) project aims at a discovery of leptonic CP violation with a precise measurement of the CP phase angle. ESSnuSB is characterized by an intense neutrino beam to be produced at ESS by a 5-MW proton beam, and the placement of the far detector at the second oscillation maximum. The aims of the near detector for ESSnuSB are neutrino flux and interaction cross section measurements. For this purpose, designs consisting of a fine-grained tracker and a 1-kiloton water Cherenkov detector are under investigation. On the other hand, the far detector will be a water Cherenkov detector with an estimated fiducial volume of 500 kilotons. The design considerations include an evaluation of the stability of the detector hall and excavation sites in deep underground mines. All of the detector simulations are based on frameworks which involve Geant4. A versatile event display toolkit for visualization and physics outreach activities has been developed

The ESSννSB project

International audienceThe ESSνSB project aims to produce a neutrino beam of unique intensity for a long-baseline oscillation measurement of CP-violation in the leptonic sector. The project, supported within the H2020 framework programme of the European Union, is currently in a conceptual design study phase, and work is ongoing within the project to develop viable solutions for the upgrade of the linear accelerator of the European Spallation Source (ESS), for the associated ring accumulator and the high-power target stations, as well as to establish solutions for the near and far detectors. The unique strength of the project lies in the capability to produce a neutrino beam that is intense enough to place the far detector at the second oscillation maximum. Such a placement will reduce the sensitivity of the experiment to systematic errors, which, due to the recently established value of the neutrino mixing angle θ13, is now known to limit the measurement precision at the first oscillation maximum. In this paper we outline the basic components of the project and discuss the status of the ongoing conceptual design study

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy

Observation of WWWWWW Production in pppp Collisions at s\sqrt s =13 TeV with the ATLAS Detector

International audienceThis Letter reports the observation of $WWW$ production and a measurement of its cross section using 139 fb$^{-1}$ of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. Events with two same-sign leptons (electrons or muons) and at least two jets, as well as events with three charged leptons, are selected. A multivariate technique is then used to discriminate between signal and background events. Events from $WWW$ production are observed with a significance of 8.0 standard deviations, where the expectation is 5.4 standard deviations. The inclusive $WWW$ production cross section is measured to be $820 \pm 100\,\text{(stat)} \pm 80\,\text{(syst)}$ fb, approximately 2.6 standard deviations from the predicted cross section of $511 \pm 18$ fb calculated at next-to-leading-order QCD and leading-order electroweak accuracy