Influence of air cavity on dose distribution in photon beam radiation therapy

Sistemi za planiranje (TPS) u radioterapiji daju dobru procenu raspodele doze u homogenim sredinama, odnosno vrednosti koje su unutar preporučenih referntnih vrednosti [1-2].Postavlja se pitanje uticaja nehomogenosti tkiva odnosno regija sa različitom elektronskom koncentracijom na raspodelu doze. Uovom radu prikazan je uticaj vazdušne šupljine na raspodelu doze duž centralne ose snopa. Ukazano je na pojavu sekundarnog nagomilavanja doze izvan regije vazdušne šupljine kao i na isporučenje niže doze unutar regije vazdušne šupljine[3]. Studija je sprovedena pomoću Monte Karlo simulacija u programskom paketu EGSnrc. U cilju optimizacije izlaganja pacijenata u radijacionoj terapiji, ove efekte bi trebalo uvrstitiu algoritme za proračun doze koje koriste sistemi za planiranje terapije.Treatment planning systems (TPS) accurately assess dose distribution in homogeneous medium. Inhomogeneities, due to varying electron densities of organs, should be accounted for in dose distribution in order to accurately deliver dose to the patient. In this paper, the influence of an air cavity on dose distribution along the central axis of the beam was investigated using the EGSnrc Monte Carlo simulation package. Secondary build-up in absorbed dose was observed in the vicinity beyond the air cavity. Optimization of protection of patients in radiation therapy requires the TPS algorithms used to calculae the dose distribution, to include these effects.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

Influence of air cavity on dose distribution in photon beam radiation therapy

Sistemi za planiranje (TPS) u radioterapiji daju dobru procenu raspodele doze u homogenim sredinama, odnosno vrednosti koje su unutar preporučenih referntnih vrednosti [1-2].Postavlja se pitanje uticaja nehomogenosti tkiva odnosno regija sa različitom elektronskom koncentracijom na raspodelu doze. Uovom radu prikazan je uticaj vazdušne šupljine na raspodelu doze duž centralne ose snopa. Ukazano je na pojavu sekundarnog nagomilavanja doze izvan regije vazdušne šupljine kao i na isporučenje niže doze unutar regije vazdušne šupljine[3]. Studija je sprovedena pomoću Monte Karlo simulacija u programskom paketu EGSnrc. U cilju optimizacije izlaganja pacijenata u radijacionoj terapiji, ove efekte bi trebalo uvrstitiu algoritme za proračun doze koje koriste sistemi za planiranje terapije.Treatment planning systems (TPS) accurately assess dose distribution in homogeneous medium. Inhomogeneities, due to varying electron densities of organs, should be accounted for in dose distribution in order to accurately deliver dose to the patient. In this paper, the influence of an air cavity on dose distribution along the central axis of the beam was investigated using the EGSnrc Monte Carlo simulation package. Secondary build-up in absorbed dose was observed in the vicinity beyond the air cavity. Optimization of protection of patients in radiation therapy requires the TPS algorithms used to calculae the dose distribution, to include these effects.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

Postal dosimetry audit of radiotherapy centers in Serbia for the period from 2019. to 2022. in terms of absorbed dose to water

U svrhu osiguranja kvaliteta sprovođenja radioterapijskih procedura, radioterapijski centri širom sveta učestvuju u programu poštanske dozimetrije koju organizuje i sprovodi Međunarodna agencija za atomsku energiju putem globalne mreže Sekundarnih Standardnih Dozimetrijskih Laboratorija. Kontrola kvaliteta podrazumeva ozračivanje pasivnih detektora zračenja (prethodno termoluminiscentnih, danas radiofotoluminiscentnih dozimetara) na poznatu vrednost apsorbovane doze u vodi u visokoenergetskim poljima x-zračenja linearnih akceleratora koji su upotrebi u redovnoj teleterapijskoj praksi. Laboratorija za zaštitu od zračenja i zaštitu životne sredine je u periodu od 2019. do 2022. godine distribuirala pasivne dozimetre radioterapijskim centrima u Srbiji.In order to perform quality assurance of radiotherapy procedures, radiotherapy centers participate in a worldwide programme of postal dosimetry external audits, organized by the International Atomic Energy Agency via the global Secondary Standard Dosimetry Laboratory network. Quality control is performed by delivering a known absorbed dose to water value to the passive ionizing radiation detectors (previously thermoluminiscent, recently radiophotoluminiscent dosimeters) in the high-energy x-radiation fields of linear accelerators which are in regular hospital use in teletherapy. Laboratory for radiation and environmental protection has distributed the passive dosimeters to the radiotherapy centers in Serbia in the period from 2019. to 2022.XXXII симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 4-6. октобар 2023. годин

Evaluation of diagnostic radiology detector performance in reference mammography radiation fields

Recommendations on diagnostic radiology calibrations are defined by the IEC and IAEA documents for molybdenum anode target material and molybdenum primary beam filtration (abbreviated as the RQR-M series). Calibration of diagnostic radiology dosimeters (ionization chambers and X-ray multimeters) can also be performed for other anode/filter combinations, including the tungsten anode / aluminium filtration setup. Performance of dosimeters can significantly vary in radiation fields defined by different anode materials and primary beam filtrations, where different spectra and first half-value layers are obtained for the same nominal X-ray tube voltages. Therefore it is important to calibrate or test dosimeters for the range of radiation qualities or conditions in which they will be used. Performance of two such detectors was evaluated.XXXII симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 4-6. октобар 2023. годин

Design and Development of OECT Logic Circuits for Electrical Stimulation Applications

This paper presents the first successful implementation of fully printed electronics for flexible and wearable smart multi-pad stimulation electrodes intended for use in medical, sports and lifestyle applications. The smart multi-pad electrodes with the electronic circuits based on organic electrochemical transistor (OECT)-based electronic circuits comprising the 3–8 decoder for active pad selection and high current throughput transistors for switching were produced by multi-layer screen printing. Devices with different architectures of switching transistors were tested in relevant conditions for electrical stimulation applications. An automated testbed with a configurable stimulation source and an adjustable human model equivalent circuit was developed for this purpose. Three of the proposed architectures successfully routed electrical currents of up to 15 mA at an output voltage of 30 V, while one was reliably performing even at 40 V. The presented results demonstrate feasibility of the concept in a range of conditions relevant to several applications of electrical stimulation.This research is part of the WEARPLEX project, funded by the European Commission’s Horizon 2020 research program under grant agreement number 825339

Growth Effects of Some Platinum(II) Complexes with Sulfur-Containing Carrier Ligands on MCF7 Human Breast Cancer Cell Line upon Simultaneous Administration with Taxol

The platinum (II)complexes, cis-[PtCl2(CH3SCH2CH2SCH3)] (Pt1), cis-[PtCl2(dmso)2] (dmso is dimethylsulfoxide; Pt2) and cis-[PtCl2(NH3)2] (cisplatin), and taxol (T) have been tested at different equimolar concentrations. Cells were exposed to complexes for 2 h and left to recover in fresh medium for 24, 48 or 72 h. Growth inhibition was measured by tetrazolium WST1 assay Analyses of the cell cycle, and apoptosis were performed by flow cytometry, at the same exposure times. The IC50 value of each platinum(II) complex as well as combination index (CI; platinum(II) complex + taxol) for various cytotoxicity levels were determined by median effects analysis

Synthesis and biological activity of new thiazole isosteres of goniofufurone and 7-epi-goniofufurone

Herein we report a total synthesis of two novel (7-epi-)goniofufurone isosteres bearing a 2-thiazolyl-4-carboxylic acid ethyl ester moiety instead of the aromatic ring at C-7

Results of IMS participation in international intercomparisons for whole body dosemeters – 10 years of study

The regular participation of an accredited individual monitoring service (IMS) in the international and/or interlaboratory intercomparisons (IC) is required according to ISO/IEC 17025:2017 standard, General requirements for the competence of testing and calibration laboratories. By taking the part in an IC, IMS shows competence, reliability, and has an opportunity to learn further and improve its measurement method. The European Dosimetry Group (EURADOS) Working Group 2 (WG2) has acknowledged the value of the regular IC and also found that data and results from it are fundamental for the harmonization of the measurement process [1]. Thus, EURADOS started a self-sustained program of IC for IMS for external radiation on a biannual basis. The results of an accredited IMS at the Department of Radiation and Environmental Protection, “VINČA” Institute of Nuclear Sciences, Belgrade, Serbia (IMS VINS) in the EURADOS IC for the period 2010-2020 (excluding 2014) are presented. IMS VINS use thermoluminescent whole body dosemeters based on two TLD-100TM (Thermo Scientific™ Harshaw™, USA) detectors. The readouts are done on the Harshaw TLD™ Model 6600 Plus Automated Reader (Thermo Fisher Scientific, USA). The whole glow curve is used for dose estimation (all of 200 channels). The calibration of the dosimetric system is done twice a year in S-Cs (previously in S-Co) field at the secondary standard dosimetry laboratory (SSDL VINS), according to ISO 4037-3:2019. The IC had 40 different reference values of personal dose equivalent, Hp(10) in noted period ranging from 0.431 mSv to 501 mSv. There were 20, 16, 22, 22, 20 dosemeters irradiated in year 2010, 2012, 2016, 2018, 2020, respectively. The radiations were done in 12 different fields: N-60, S-Co, S-Cs, N-40, N-150, S-Cs+Sr90, S-Cs+N-40, W-110, S-Cs+W-250, W-60, S-Cs+W-80, and S-Cs+N-150. The relative response (R) range is from 0.23 to 2.26. Quantile values for R are: 0.23, 0.79, 0.90, 1.1, and 2.26, respectively for (0%, 25 %, 50 %, 75 % and 100 % of points). Mean and standard deviation of R are 0.97 and 0.30, respectively. The performance limits are established according to ISO 14146 trumpet-curve [1]. Due to trumpet-curve there were 6 outliers (2 in 2010, 4 in 2016). All of the outliers were for reference dose around 1 mSv and lower. One outlier from 2010 was irradiated in N-40 field and 30° of incident angle. The other outlier was irradiated in the S-Cs field, without any rotation, and thus should have had a satisfying response. The possible explanation is an insensitive TL detector. The outliers in 2016 were all for N-40 quality and ±60° angle. Thus, considering the low number of outliers (only one true outlier) and expected dosemeters faulty response for given irradiation parameters, we conclude that the IMS VINS dosimetry system had satisfactory behavior during IC from 2010-2020.X JUBILEE International Conference on Radiation in Various Fields of Research : RAD 2022 (Spring Edition) : book of abstracts; June 13-17, 2022; Herceg Novi, Montenegr

Echocardiography-based Left Ventricle Cardiac Hypertrophy Simulations

Clinical scenarios can be evaluated using numerical modeling of the cardiac cycle prior to experimental or clinical application. Changes in wall thickness, displacement fields, and general cardiac function are all affected by hypertrophy. In our study, we calculated the effects of eccentric and concentric hypertrophy and monitored changes in ventricular thickness and shape. Concentric hypertrophy results in thicker walls, while eccentric hypertrophy results in thinner walls. Passive stresses were calculated using recently established material modals based on Holzapfel’s work. Our modeling approach is based on composite shell finite elements, allowing easier and more efficient modeling compared to traditional 3D finite elements. A left ventricular model was constructed using echocardiographic images. Our modeling technology is based on accurate patient-specific geometries and realistic constitutive curves, so it can be used as the basis for real-world applications. Our model can be used to test medical hypotheses about the development of hypertrophy in healthy and diseased hearts under the influence of different conditions and factors.Book of abstract: 4th Belgrade Bioinformatics Conference, June 19-23, 202