Wyniki wyszukiwania - Biblioteka Nauki

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High resolution 2D plastic scintillator detectors for radiotherapy departments

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Woźniak G. Z. , Kozłowska B.

Polish Journal of Medical Physics and Engineering

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2023

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tom Vol. 29, Iss. 2

92--103

EN

Plastic scintillation detectors (PSD) have been developed for over four decades and are widely used in a variety of fields, but one can find relatively few reports of their clinical use compared to other dosimetric solutions. The inexpensive detector setup made of a Saint-Gobain BC-400 plastic scintillator and commercially available on the market CMOS-based DSLR Pentax camera was investigated. Build PSD detectors were irradiated with 6, 10 and 15 MV flattening filtered (FF) and 6 and 10 MV flattening filter free (FFF) photon beams using a clinical linear accelerator. Data were processed using Matlab software to remove background and artefacts. A comparison of the spatial resolution parameters to the Gafchromic EBT3 films was performed. Average dose difference between TPS and PSD was 1.1%. The measured spatial resolution was 0.29 mm, and it differed from the film by 1.1%. MTF50 for PSD was 0.57 mm higher than the Gafchromic film. Signal to dose fit function with an R-square equal to 0.999 was established. The standard deviation of mean pixels value for a series of measurements was below 0.1%, for variable dose rate dependence was below 0.6% and for different energies 1.1%. It was demonstrated that such a setup allows a satisfactory signal-to-dose dependence and provides high spatial resolution at an affordable price compared to a 2D ion chamber or a diode detector array. Moreover, PSDs are reusable and provide a simple readout compared to Gafchromic films commonly used in radiotherapy departments. Variable parameters of the camera allow to select signal values at the optimal level. The system presented excellent signal stability, high image resolution and a simple signal-to-dose relationship which encourages further work to investigate PSDs for use in radiation therapy departments.

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Clinical advantages of using unflattened 6-MV and 10-MV photon beams generated by the medical accelerator Elekta Versa HD based on their dosimetric parameters in comparison to conventional beams

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Baic B. , Kozłowska B. , Kwiatkowski R. , Dybek M.

Nukleonika

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2019

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tom Vol. 64, No. 3

77--86

EN

Photon beams with wide energy ranges from 4 MV to 25 MV are commonly used in radiotherapy nowadays. In recent years, there has been a strong interest in a certain modification of a radiotherapeutic apparatus by the application of the so-called flattening filter-free (FFF) beam. Several advantages of FFF beams over standard flattening filter (FF) beams are noticed, and this technical solution has aroused great interest among radiotherapeutic facilities. The goal of the present study is to investigate the differences between the conventional FF and unflattened FFF 6-MV and 10-MV photon beams in some basic dosimetric parameters and their influence on the whole radiotherapeutic treatment. The data provided here include the detailed characteristics as follows: percent depth dose (PDD), beam profile, edge of a half-profile, total scatter correction factor (TSCF) and head scatter correction factor (HSCF) for FF and FFF 6-MV and 10-MV photon beams from the Elekta Versa HD accelerator in the Katowice Oncology Center in Poland.

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Comparison of dose distributions in target areas and organs at risk in conformal and VMAT techniques and dose verifications with the use of thermoluminescence dosimetry

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Paluch-Ferszt M. , Kozłowska B. , Dybek M.

Nukleonika

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2020

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tom Vol. 65, No. 4

217--222

EN

The aim of the present study is to compare dose distributions and their verification in target areas and organs at risk (OAR) in conformal and volumetric modulated arc therapy (VMAT) techniques. Proper verification procedures allow the removal of the major sources of errors, such as incorrect application of a planning system, its insufficient or cursory commissioning, as well as an erroneous interpretation of the obtained results. Three target areas (head and neck, chest, and pelvic) were selected and the treatment was delivered based on plans made using collapsed cone convolution and Monte Carlo algorithms with 6-MV photon beams, adopting conformal and VMAT techniques, respectively. All the plans were prepared for the anthropomorphic phantom. Dose measurements were performed with TL detectors made of LiF phosphor doped with magnesium and titanium (LiF:Mg,Ti). This paper presents the results of TL measurements and calculated doses, as well as their deviations from the treatment planning system (TPS) in the three planned target areas. It was established that the algorithms subject to analysis differ, particularly in dose calculations for highly inhomogeneous regions (OAR). Aside from the need to achieve the dose intended for the tumour, the choice of irradiation technique in teleradiotherapy should be dictated by the degree of exposure toindividual critical organs during irradiation. While nothing deviated beyond the bounds of what is acceptable by international regulatory bodies in plans from TPS, clinically one must be more cautious with the OAR areas.

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Erratum to “Radon incomparison tests – Katowice, 2016” [Nukleonika 2020;65(2):127-132, doi:10.2478/nuka-2020-0020]

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Chałupnik S. , Skubacz K. , Wysocka M. , Mazur J. , Bonczyk M. , Kozak K. , Grządziel D. , Urban P. , Tchorz-Trzeciakiewicz D. , Kozłowska B. , Walencik-Łata A. , Podstawczyńska A. , Olszewski J. , Bartak J. , Karpińska M. , Wołoszczuk K. , Dohojda M. , Nowak J. , Długosz-Lisiecka M. , Foerster E. , Przylibski T. A.

Nukleonika

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2021

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tom Vol. 66, No. 2

80

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Radon intercomparison tests : Katowice, 2016

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Chałupnik S. , Skubacz K. , Wysocka M. , Mazur J. , Bonczyk M. , Kozak K. , Grządziel D. , Urban P. , Tchorz-Trzeciakiewicz D. , Kozłowska B. , Walencik-Łata A. , Podstawczyńska A. , Olszewski J. , Bartak J. , Karpińska M. , Wołoszczuk K. , Dohojda M. , Nowak J. , Długosz-Lisiecka M. , Foerster E. , Przylibski T. A.

Nukleonika

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2020

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tom Vol. 65, No. 2

127--132

EN

At the beginning of the year 2016, the representatives of the Polish Radon Centre decided to organize proficiency tests (PTs) for measurements of radon gas and radon decay products in the air, involving radon monitors and laboratory passive techniques. The Silesian Centre for Environmental Radioactivity of the Central Mining Institute (GIG), Katowice, became responsible for the organization of the PT exercises. The main reason to choose that location was the radon chamber in GIG with a volume of 17 m3 , the biggest one in Poland. Accordingly, 13 participants from Poland plus one participant from Germany expressed their interest. The participants were invited to inform the organizers about what types of monitors and methods they would like to check during the tests. On this basis, the GIG team prepared the proposal for the schedule of exercises, such as the required level(s) of radon concentrations, the number and periods of tests, proposed potential alpha energy concentration (PAEC) levels and also the overall period of PT. The PT activity was performed between 6th and 17th June 2016. After assessment of the results, the agreement between radon monitors and other measurement methods was confirmed. In the case of PAEC monitors and methods of measurements, the results of PT exercises were consistent and confirmed the accuracy of the calibration procedures used by the participants. The results of the PAEC PTs will be published elsewhere; in this paper, only the results of radon intercomparison are described.

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National comparison of methods for determination of radon in water

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Mazur J. , Kozak K. , Grządziel D. , Guguła S. , Mroczek M. , Kozłowska B. , Walencik-Łata A. , Podgórska Z. , Wołoszczuk K. , Przylibski T. A. , Kowalska A. , Domin E. , Wysocka M. , Chałupnik S. , Chmielewska I. , Długosz-Lisiecka M. , Szajerski P. , Chau N. D. , Krakowska P. , Pliszczyński T. , Ośko J. , Dymecka M. , Mazurek D.

Nukleonika

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2020

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tom Vol. 65, No. 2

77--81

EN

The article describes three interlaboratory experiments concerning 222Rn determination in water samples. The first two experiments were carried out with the use of artificial radon waters prepared by the Laboratory of Radiometric Expertise (LER), Institute of Nuclear Physics, Polish Academy of Sciences in Kraków in 2014 and 2018. The third experiment was performed using natural environment waters collected in the vicinity of the former uranium mine in Kowary in 2016. Most of the institutions performing radon in water measurements in Poland were gathered in the Polish Radon Centre Network, and they participated in the experiments. The goal of these exercises was to evaluate different measurement techniques used routinely in Polish laboratories and the laboratories’ proficiency of radon in water measurements. In the experiment performed in 2018, the reference values of 222Rn concentration in water were calculated based on the method developed at LER. The participants’ results appeared to be worse for low radon concentration than for high radon concentrations. The conclusions drawn on that base indicated the weaknesses of the used methods and probably the sampling. The interlaboratory experiments, in term, can help to improve the participants’ skills and reliability of their results.