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Characterization of photons and neutrons of megavoltage therapeutic accelerators

dc.contributor.advisorKrmar, Miodrag
dc.contributor.otherPetrović, Borislava
dc.contributor.otherKrmar, Miodrag
dc.contributor.otherKlisurić, Olivera
dc.contributor.otherNikolov, Jovana
dc.contributor.otherUdovičić, Vladimir
dc.creatorTot, Arpad
dc.date.accessioned2018-06-01T10:28:14Z
dc.date.available2018-06-01T10:28:14Z
dc.date.available2020-07-03T13:40:05Z
dc.date.issued2018-05-28
dc.identifier.urihttp://nardus.mpn.gov.rs/handle/123456789/9500
dc.identifier.urihttps://www.cris.uns.ac.rs/DownloadFileServlet/Disertacija151972730767145.pdf?controlNumber=(BISIS)107144&fileName=151972730767145.pdf&id=11005&source=NaRDuS&language=srsr
dc.identifier.urihttps://www.cris.uns.ac.rs/record.jsf?recordId=107144&source=NaRDuS&language=srsr
dc.identifier.urihttps://www.cris.uns.ac.rs/DownloadFileServlet/IzvestajKomisije151972731871988.pdf?controlNumber=(BISIS)107144&fileName=151972731871988.pdf&id=11006&source=NaRDuS&language=srsr
dc.description.abstractPoznavanje spektra x-zračenja kao i drugih osobina je od izuzetnog  značaja  kako za planiranje radijacione terapije tako i sa aspekta zaštite pacijenta i osoblja. Takođe, poznavanje svojstava  neutrona  nastalih  u interakciji fotona sa materijalima oko akceleratora, je od izuzetnog značaja sa dozimetrijskog aspekta. Poslednjih godina sve se više upotrebljavaju linearni akceleratori bez homogenizacionog filtera tzv. FFF (Flatteninig Filter Free), a kako su karakteristike snopa u toma načinu rada akceleratora još uvek nedovoljno ispitane, njima smo posvetili posebnu pažnju. Urađena su i detaljna dozimetrijska merenja fotona kako u radu sa homogenizacionim filterom (FF) tako i bez njega (FFF), kao i dozimetrijsko merenje neutrona. Direktno merenje samog spektra nekim od detektora (NaI ili HPGe) nije moguće zbog visokih intenziteta stoga smo u radu koristili indirektne metode i to aktivacionu analizu i atenuacionu analizu. Urađena su detaljna dozimetrijska merenja ekvivalentne doze neutrona u terapijskoj sobi sa dva zaokreta hodnika i na osnovu rezultata predložena je korekcija metode za izračunavanje neutronske doze na ulaznim vratima.  Fotoaktivacionimmerenjima, gde su se u oba načina rada terapijskog  akceleratora pratile aktivnosti izomera 115m In, ustanovljeno je da se kod dva tipa  akceleratora  (Elekta Versa HD, Varian TrueBeam)  oblik spektra u visokoenergetskom delu znatno razlikuje, kao i da postoji razlika u obliku spektra na ivici polja i u njegovoj sredini.  Atenuacionom analizom  na osnovu  standardnog metoda rekonstrukcije fotonskog spektra putem Laplasovih transforma, dobijene su izvesne razlike u oblicima spektara za dva režima rada. Takođe,  rekonstrukcijom spektra putem odabira parametara korekcine funkcije koja bi teorijski oblik spektra (Šifova funkcija) trebao da prevede u realan spektar za oba režima rada dobijene su izvesne razlike u oblicima spektra. Dozimetrijska merenja fotonske doze na ulaznim vratima terapijske sobe sa  jednim zaokretom, sa i bez homogenizacionog filtera za različite veličine polja i sa i bez vodenog kanistera koji simulira pacijenta u snopu, pokazuju da je izmerena  doza na ulaznim vratima u FFF modu rada uvek niža od izmerene doze u slučaju da se koristi homogenizacioni filter.sr
dc.description.abstractKnoweledge of the x-ray spectrum as well as other characteristics of the beam is of  great  importance both for the planning of radiotherapy as well as for the protection of patients and staff. Also, the knowledge of the neutron properties generated  in the interaction of photons with materials around the accelerator is of great importance from the dosimetric aspect. In recent years, linear accelerators are increasingly used without a flattening filter, so-called FFF (Flatteninig Filter Free), and as the characteristics of the  beam in this mode of operation of the accelerator  are still insufficiently  investigated, we paid special attention to them. Detailed dosimetric measurements of photons were performed both with (FFF) and without the flattening  filter (FF), as well as the dosimetric measurement of the neutron. Direct  measurement of the spectrum itself by detectors (NaI or HPGe) is not possible due to  high intensities, therefore, we used indirect methods in this work, both activation analysis and attenuation analysis. Detailed  dosimetric measurements of the  neutron  equivalent dose in the therapeutic  room with two band maze  were made and based on the results, correction of the method for calculating the neutron dose at the entrance door was proposed. It was found by photoactivation measurements, where the activities of the isomer 115mIn were investigated, that in the two types of accelerators (Elekta Versa HD, Varian TrueBeam) the spectrum shape in the high-energy part is significantly  different, and that there is a spectrum difference in the edge of the field and in the middle of the field. Attenuation analysis, based on the standard method of reconstructing the photon spectrum through Laplace transforms, showed  some differences in the spectra of  the two working  modes  of accelerators. Also, by reconstructing the spectrum by correction function  that  should transform  the  theoretical spectrum  form (the Schiff function)  into a real spectrum for both modes of operation, certain differences  in spectrum shapes were  obtained. Dosimetric measurements of the photon dose at the entrance door of treatment room  with a single maze with and without a homogenizing filter for different field sizes and with and without a water canister  which simulates  the patient in a beam showed  that the measured dose at the entrance door in the FFF mode is always lower  than the measured doses in FF mode.en
dc.languagesr (latin script)
dc.publisherУниверзитет у Новом Саду, Природно-математички факултетsr
dc.rightsopenAccessen
dc.sourceУниверзитет у Новом Садуsr
dc.subjectlinearni akceleratorisr
dc.subjectlinear acceleratorsen
dc.subjectfotnisr
dc.subjectneutronisr
dc.subjectdozimetrijasr
dc.subjectaktivaciona analizasr
dc.subjectatenuaciona analizasr
dc.subjectphotonsen
dc.subjectneutronsen
dc.subjectdosimetryen
dc.subjectactivation analysisen
dc.subjectattenuation analysisen
dc.titleKarakterizacija fotona i neutrona megavoltažnih terapijskih akceleratorasr
dc.title.alternativeCharacterization of photons and neutrons of megavoltage therapeutic acceleratorsen
dc.typedoctoralThesissr
dc.rights.licenseBY-NC-ND
dcterms.abstractКрмар, Миодраг; Николов, Јована; Петровић, Борислава; Удовичић, Владимир; Крмар, Миодраг; Клисурић, Оливера; Тот, Aрпад; Карактеризација фотона и неутрона мегаволтажних терапијских акцелератора; Карактеризација фотона и неутрона мегаволтажних терапијских акцелератора;
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/37268/Disertacija.pdf
dc.identifier.fulltexthttp://nardus.mpn.gov.rs/bitstream/id/37269/IzvestajKomisije.pdf


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