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    Wyświetlanie 1-4 z 4
    Tytuł:
    Monte Carlo study on a new concept of a scanning photon beam system for IMRT
    Autorzy:
    Wysocka-Rabin, A. M.
    Hartmann, G. H.
    Powiązania:
    https://bibliotekanauki.pl/articles/147603.pdf
    Data publikacji:
    2011
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    Monte Carlo (MC) simulations
    medical accelerators
    intensity-modulated radiation therapy (IMRT)
    Opis:
    Intensity-modulated radiation therapy (IMRT) is almost exclusively realized using a multi-leaf collimator (MLC). In this work we investigated alternative approaches to realize an IMRT - scanning photon beam system. The technical realization of this concept required investigating the influence of various design parameters on the final small photon beam. This was done using Monte Carlo (MC) simulation methods. The resulting photon beam that is to be scanned should have a diameter well less than 10 mm at a source-surface distance (SSD), and the penumbra should be as small as possible. A first draft for this system, based on the PRIMUS 6 MV accelerator at DKFZ (Deutsches Krebsforshungszentrum), was proposed and modeled using the BEAMnrc/EGSnrc MC code. We then proposed and studied a new geometry of the source-target-collimator system. Calculations were done for 108 particles, using an electron energy cut-off (ECUT) = 0.7 MeV, and a photon energy cut-off (PCUT) = 0.01 MeV. The influence of different collimator parameters, different target construction and various incident electron beam characteristics was studied. Calculations of the dose absorbed in the water were performed for 8 different collimators at a distance of 40 cm from the collimator exit, which is the medical requirement. Results of the dose distribution calculations are presented as photon beam profiles with the values of full width at half-maximum (FWHM) and penumbra (PM) for every beam profile. The influence of target construction was studied for different thicknesses of target and material minimizing electron contamination. The influence of the following characteristics of the incident electron beam was also investigated: size of electron beam, energy, displacement of the beam from the axis of target-collimator system, shape of the electron beam profile. The field dose distribution of the photon beam was calculated for the collimators giving the beam profiles. Basing on the work performed in this investigation, it will be possible to define adequate parameters for the target-collimator system as well as on the scanning electron beam for new IMRT system.
    Źródło:
    Nukleonika; 2011, 56, 4; 291-297
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Measurements of doses from photon beam irradiation and scattered neutrons in an anthropomorphic phantom model of prostate cancer: a comparison between 3DCRT, IMRT and tomotherapy
    Autorzy:
    Kowalik, A.
    Jackowiak, W.
    Malicki, J.
    Skórska, M.
    Adamczyk, M.
    Konstanty, E.
    Piotrowski, T.
    Polaczek-Grelik, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/146348.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    3DCRT
    IMRT
    low doses
    neutron doses
    thermoluminescent detectors (TLD)
    tomotherapy
    Opis:
    The rapid development of new radiotherapy technologies, such as intensity modulated radiotherapy (IMRT) or tomotherapy, has resulted in the capacity to deliver a more homogenous dose in the target. However, the higher doses associated with these techniques are a reason for concern because they may increase the dose outside the target. In the present study, we compared 3DCRT, IMRT and tomotherapy to assess the doses to organs at risk (OARs) resulting from photon beam irradiation and scattered neutrons. Material and methods. The doses to OARs outside the target were measured in an anthropomorphic Alderson phantom using thermoluminescence detectors (TLD 100) 6Li (7.5%) and 7Li (92.5%). The neutron fluence rate [cm–2·s–1] at chosen points inside the phantom was measured with gold foils (0.5 cm diameter, mean surface density of 0.108 g/cm3). Results. The doses [Gy] delivered to the OARs for 3DCRT, IMRT and tomotherapy respectively, were as follows: thyroid gland (0.62 ± 0.001 vs. 2.88 ± 0.004 vs. 0.58 ± 0.003); lung (0.99 ± 0.003 vs. 4.78 ± 0.006 vs. 0.67 ± 0.003); bladder (80.61 ± 0.054 vs. 53.75 ± 0.070 vs. 34.71 ± 0.059); and testes (4.38 ± 0.017 vs. 6.48 ± 0.013 vs. 4.39 ± 0.020). The neutron dose from 20 MV X-ray beam accounted for 0.5% of the therapeutic dose prescribed in the PTV. The further from the field edge the higher the contribution of this secondary radiation dose (from 8% to ~45%). Conclusion. For tomotherapy, all OARs outside the therapeutic field are well-spared. In contrast, IMRT achieved better sparing than 3DCRT only in the bladder. The photoneutron dose from the use of high-energy X-ray beam constituted a notable portion (0.5%) of the therapeutic dose prescribed to the PTV.
    Źródło:
    Nukleonika; 2017, 62, 1; 29-35
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wyznaczanie jednorodnych dawek równoważnych dla pacjentów leczonych techniką Simultaneous Integrated Boost
    Determination of Equivalent Uniform Doses for patient treated with the Simultaneous Integrated Boost technique
    Autorzy:
    Araszkiewicz, Martyna
    Korgul, Agnieszka
    Kukołowicz, Paweł
    Powiązania:
    https://bibliotekanauki.pl/articles/2146769.pdf
    Data publikacji:
    2020
    Wydawca:
    Indygo Zahir Media
    Tematy:
    jednorodna dawka równoważna
    radioterapia
    IMRT
    Simultaneous Integrated Boost
    PTV
    equivalent Uniform Dose
    radiotherapy
    Opis:
    Celem radioterapii jest dostarczenie zaplanowanej dawki promieniowania do targetu przy jednoczesnym zminimalizowaniu dawki deponowanej w narządach krytycznych. Istnieją przypadki, gdzie w planie leczenia jednego pacjenta uwzględniono kilka obszarów tarczowych (ang. Planning Target Volume – PTV). Jedną z możliwych technik napromieniania jest wtedy tzw. technika Simultaneous Integrated Boost (SIB). Polega ona na jednoczesnym napromienianiu różnymi dawkami więcej niż jednej objętości tarczowej. Ze względu na konieczność jednoczesnego podania dawek w kilku targetach otrzymują one dawkę różną od zleconej. W pracy, stosując koncepcję jednorodnej dawki równoważnej (ang. Equivalent Uniform Dose – EUD), oceniono wzajemny wpływ dawek deponowanych w poszczególnych targetach.
    Radiotherapy aims to deliver an appropriate dose of ionizing radiation to the target, minimizing the doses in critical organs. There are cases where several Planning Target Volume (PTV) are planned in the treatment plan for one patient that require different doses to be deposited. In such cases, one of the possible irradiation techniques is the so-called Simultaneous Integrated Boost (SIB) technique, in which all PTV are simultaneously irradiated with different doses. Due to the existing Beam Penumbra Effect, the application of a dose in one PTV affects the doses in the second PTV receiving a lower dose. In this paper, using the concept of the Equivalent Uniform Dose – EUD (EUD) the mutual influence of doses deposited in particular PTVs was assessed.
    Źródło:
    Inżynier i Fizyk Medyczny; 2020, 9, 3; 159--160
    2300-1410
    Pojawia się w:
    Inżynier i Fizyk Medyczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of set-up verification with the analysis of systematic and random errors in radiotherapy - a study of the Great Poland Cancer Centre
    Autorzy:
    Szczurek, Ł.
    Skrobała, A.
    Piotrowski, T.
    Jodda, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/147744.pdf
    Data publikacji:
    2008
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    electronic portal devices
    positioning patient
    three-dimensional-conformal radiation therapy (3D-CRT)
    intensity-modulated radiation therapy (IMRT)
    oncology
    Opis:
    The aim of this study was the examination of influence of location tumors and methods of immobilizing on values of geometrical errors during treatment, and the analysis of set-up errors in reference to the method of irradiation in three groups of patients before and after corrections. This study included three groups of patients with prostate cancer (59 patients, 277 portal images), head and neck (60 patients, 285 portal images) and brain tumor (45 patients, 175 portal images). Ratios of IMRT vs. 3D-CRT were respectively: in I group 76% vs. 24%, in II group 95% vs. 5% and III group 83% vs. 17%. Set-up errors were compared in reference to the technique of irradiation and stage of treatment. The displacements were significantly higher in the first group compared with head, neck and brain tumors; 5.66, 4.05, 3.93 mm, respectively. The values of the vector lengths were significantly dependent on the type of irradiation technique (3D-CRT vs. IMRT) only in the first group (p < 0.001). The average of vector length in I, II and III group were significantly reduced from; 5.67, 4.02, 3.91 mm to 5.13, 3.63, 3.57 mm after correction, respectively. The Spearman test is indicating a low negative correlation between set-up errors and the following fractions. The applied methods of patients positioning with prostate cancer produce a worse repeatability than the ones used for patients with head, neck and brain cancers. Portal verification reduces values of set-up errors. Significant differences in the magnitude of displacements before and after correction were observed. No significant differences between value of displacement and number of fraction were revealed.
    Źródło:
    Nukleonika; 2008, 53, 4; 167-171
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-4 z 4

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