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doctoral thesis
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Dosimetric uncertainness in verification of intensity modulated photon beams
Slaven Jurković (2010)
University of Zagreb
Faculty of Science
Department of Physics
Metadata
TitleDozimetrijske nesigurnosti pri verifikaciji fotonskih snopova linearnog akceleratora modulirane jakosti
AuthorSlaven Jurković
Mentor(s)Dario Faj
Abstract
U disertaciji je opisana metoda za izračun oblika modulatora jakosti snopa linearnog akceleratora Osobitost metode je to što kod snopova s izrazito nehomogenim poprečnim presjecima, raspršeno zračenje uzima u obzir na egzaktniji način nego što je to bilo činjeno ranije. Metoda je primjenjiva u većini kliničkih situacija, a njena verifikacija je napravljena dozimetrijom ionizacijskim komorama i radiografskim filmom u različitim fantomima. Pri tome je na temelju mjerenja ionizacijskim komorama procjenjivan oblik kompenzatora, a radiografskim filmom su mjerene dvo-dimenzionalne raspodjele doze. Poznato je da je dozimetrija fotonskih snopova linearnog akceleratora modulirane jakosti, zbog nehomogene raspodjele doze, vrlo složena. Posebno stoga što se modulacijom jakosti snopa mijenja i energijski spektar snopa. Zbog toga su ispitane mogućnost korištenja i točnost različitih tipova detektora za mjerenje doznih distribucija snopova fotona. Korištene su ionizacijske komore malog volumena, poluvodički detektori različitih volumena, detektor od amorfnog silicija i radiografski film. Izmjerene raspodjele doze su uspoređivane međusobno, kao i sa raspodjelama dobivenim pomoću Monte Carlo simulacije transporta čestica. Na temelju toga predložena je najtočnija metoda za verifikaciju raspodjele doze u fotonskim snopovima linearnog akceleratora modulirane jakosti.
Keywordsintensity modulation compenstators dosimetry Monte Carlo simulation
Parallel title (English)Dosimetric uncertainness in verification of intensity modulated photon beams
Committee MembersMladen Vrtar (committee chairperson)
Jasminka Brnjas Kranjević (committee member)
Dario Faj (committee member)
GranterUniversity of Zagreb
Faculty of Science
Lower level organizational unitsDepartment of Physics
PlaceZagreb
StateCroatia
Scientific field, discipline, subdisciplineNATURAL SCIENCES
Physics
UDK53
NATURAL SCIENCES
Physics
Study programme typeuniversity
Study levelpostgraduate
Study programmePhysics
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2010-11-12
Parallel abstract (English)
The doctoral thesis presents method for the calculation of the compensators’ shape to modulate linear accelerators’ beams. Characteristic of the method is more strict calculation of the scattered radiation in beams with an inhomogeneous cross-section than it was before. Method could be applied in various clinical situations. It's dosimetric verification was made in phantoms, measuring dose distributions using ionization chambers as well as radiographic film. Therefore, ionization chambers were used for the evaluation of modulator shape and film was used for the evaluation of two-dimensional dose distributions. It is well known that dosimetry of the intensity modulated photon beams is rather complicated regarding inhomogeneity of the dose ditribution. The main reason for that is the beam modulator which changes spectral distribution of the beam. Possibility of use different types of detectors for the measurements of dose distributions in modulated photon beams and their accuracy were examined. Small volume ionization chambers, different diodes and amorphus silicon detector and radigraphic film were used. Measured dose distributions were compared between each other as well as with distributions simulated using Monte Carlo particle transport algorithm. In this way the most accurate method for the verification of modulate photon beams is suggested.
Parallel keywords (Croatian)modulacija intenziteta kompenzatori dozimetrija Monte Carlo simulacija
Extent87 str.
Versionaccepted version
Resource typetext
Access conditionOpen access
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:217:429440