The human body is constantly exposed to ionizing radiation of different qualities. Especially the exposure to high-LET (linear energy transfer) particles increases due to new tumor therapy methods using e.g. carbon ions. Furthermore, upon radiation accidents, a mixture of radiation of different quality is adding up to human radiation exposure. Finally, long-term space missions such as the mission to mars pose great challenges to the dose assessment an astronaut was exposed to. Currently, DSB counting using γH2AX foci is used as an exact dosimetric measure for individuals. Due to the size of the γH2AX IRIF of ~ 0.6 μm, it is only possible to count DSB when they are separated by this distance. For high-LET particle exposure, the distance of the DSB is too small to be separated and the dose will be underestimated. In this study, we developed a method where it is possible to count DSB which are separated by a distance of ~ 140 nm. We counted the number of ionizing radiation-induced pDNA-PKcs (DNA-PKcs phosphorylated at T2609) foci (size = 140 nm ± 20 nm) in human HeLa cells using STED super-resolution microscopy that has an intrinsic resolution of 100 nm. Irradiation was performed at the ion microprobe SNAKE using high-LET 20 MeV lithium (LET = 116 keV/μm) and 27 MeV carbon ions (LET = 500 keV/μm). pDNA-PKcs foci label all DSB as proven by counterstaining with 53BP1 after low-LET γ-irradiation where separation of individual DSB is in most cases larger than the 53BP1 gross size of about 0.6 μm. Lithium ions produce (1.5 ± 0.1) IRIF/μm track length, for carbon ions (2.2 ± 0.2) IRIF/μm are counted. These values are enhanced by a factor of 2-3 compared to conventional foci counting of high-LET tracks. Comparison of the measurements to PARTRAC simulation data proof the consistency of results. We used these data to develop a measure for dosimetry of high-LET or mixed particle radiation exposure directly in the biological sample. We show that proper dosimetry for radiation up to a LET of 240 keV/μm is possible.
- MeSH
- biologické markery MeSH
- dávka záření MeSH
- dvouřetězcové zlomy DNA účinky záření MeSH
- fluorescenční mikroskopie metody MeSH
- fosforylace účinky záření MeSH
- HeLa buňky MeSH
- lidé MeSH
- lineární přenos energie MeSH
- lithium škodlivé účinky MeSH
- oprava DNA účinky záření MeSH
- proteinkinasy účinky záření MeSH
- radiační expozice MeSH
- radiometrie metody MeSH
- těžké ionty škodlivé účinky MeSH
- uhlík škodlivé účinky MeSH
- záření gama škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Plasmid DNA is commonly used as a simpler substitute for a cell in studies of early effects of ionizing radiation because it allows to determine yields of primary DNA lesions. Experimental studies often employ plasmids of different lengths, in different concentrations in the aqueous solution. Influence of these parameters on the heavy-ion induced yields of primary DNA damage has been studied, using plasmids pUC19 (2686 bp), pBR322 (4361 bp) and pKLAC2 (9107 bp) in 10 and 50 ng/μl concentration. Results demonstrate the impact of plasmid length, while no significant difference was observed between the two concentrations. The uncertainty of the results is discussed.
- MeSH
- algoritmy MeSH
- antioxidancia farmakologie MeSH
- DNA účinky záření MeSH
- ionizující záření MeSH
- lineární přenos energie MeSH
- metoda Monte Carlo MeSH
- nejistota MeSH
- plazmidy účinky záření MeSH
- polypropyleny chemie MeSH
- poškození DNA účinky záření MeSH
- těžké ionty MeSH
- vztah dávky záření a odpovědi MeSH
- záření gama MeSH
- Publikační typ
- časopisecké články MeSH
Track-etched detectors are commonly used also for radiation monitoring onboard International Space Station. To be registered in track-etched detectors, the particle needs to meet several criteria-it must have linear energy transfer above the detection threshold and strike the detector's surface under an angle higher than the so-called critical angle. Linear energy transfer is then estimated from calibration curve from the etch rate ratio V that is calculated from parameters of individual tracks appearing on the detector's surface after chemical etching. It has been observed that V can depend on the incident angle and this dependence can vary for different detector materials, etching and evaluating conditions. To investigate angular dependence, detectors (Harzlas TD-1) were irradiated at HIMAC by several ions under angles from 0° to 90°. The correction accounting not only for critical angle but also for dependence of V on the incident angle is introduced and applied to spectra measured onboard International Space Station.
- MeSH
- dávka záření MeSH
- ionty MeSH
- kalibrace MeSH
- kosmická loď * MeSH
- kosmické záření MeSH
- kosmický let přístrojové vybavení MeSH
- lineární přenos energie MeSH
- monitorování radiace přístrojové vybavení metody MeSH
- termoluminiscenční dozimetrie přístrojové vybavení metody MeSH
- těžké ionty * MeSH
- Publikační typ
- časopisecké články MeSH
A compromised detection of radiation-induced plasmid DNA fragments results in underestimation of calculated damage yields. Electrophoretic methods are easy and cheap, but they can only detect a part of the fragments, neglecting the shortest ones. These can be detected with atomic force microscopy, but at the expense of time and price. Both methods were used to investigate their capabilities to detect the DNA fragments induced by high-energetic heavy ions. The results were taken into account in calculations of radiation-induced yields of single and double strand breaks. It was estimated that the double strand break yield is twice as high when the fragments are at least partially detected with the agarose electrophoresis, compared to when they were completely omitted. Further increase by 13% was observed when the measured fragments were corrected for the fraction of the shortest fragments up to 300 base pairs, as detected with the atomic force microscopy. The effect of fragment detection on the single strand break yield was diminished.
Fundamental research on the harmful effects of ionizing radiation on living cells continues to be of great interest. Recently, priority has been given to the study of high-charge and high-energy (HZE) ions that comprise a substantial part of the galactic cosmic ray (GCR) spectra that would be encountered during long-term space flights. Moreover, predictions of the delayed genetic effects of high linear energy transfer (LET) exposure is becoming more important as heavy ion therapy use is increasing. This work focuses mainly on the basic research on the delayed effects of HZE ions on V79 Chinese hamster cells, with emphasis on the induction of HPRT mutations after prolonged expression times (ET). The research was conducted under various irradiation conditions with accelerated ions 18O (E=35.2MeV/n), 20Ne (E=47.7MeV/n and 51.8MeV/n), and 11B (E=32.4MeV/n), with LET in the range from 49 to 149 keV/μm and with 60Co γ-rays. The HPRT mutant fractions (MF) were detected in irradiated cells in regular intervals during every cell culture recultivation (every 3days) up to approximately 40days (70-80 generations) after irradiation. The MF maximum was reached at different ET depending on ionizing radiation characteristics. The position of the maximum was shifting towards longer ET with increasing LET. We speculate that the delayed mutations are created de novo and that they are the manifestation of genomic instability. Although the exact mechanisms involved in genomic instability initiation are yet to be identified, we hypothesize that differences in induction of delayed mutations by radiations with various LET values are related to variations in energy deposition along the particle track. A dose dependence of mutation yield is discussed as well.
- MeSH
- buněčné linie MeSH
- Cricetulus MeSH
- fibroblasty účinky záření MeSH
- hypoxanthinfosforibosyltransferasa genetika MeSH
- křečci praví MeSH
- lineární přenos energie MeSH
- mutace * MeSH
- nestabilita genomu účinky záření MeSH
- těžké ionty škodlivé účinky MeSH
- vztah dávky záření a odpovědi MeSH
- záření gama * MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The annual effective doses of aircrew members often exceed the limit of 1 mSv for the public due to the increased level of cosmic radiation at the flight altitudes, and thus, it is recommended to monitor them. Aircrew dosimetry is usually performed using special computer programs mostly based on results of Monte Carlo simulations. Contemporary, detectors are used mostly for validation of these computer codes, verification of effective dose calculations and for research purposes. One of such detectors is active silicon semiconductor deposited energy spectrometer Liulin. Output quantities of measurement with the Liulin detector are the absorbed dose in silicon D and the ambient dose equivalent H*(10); to determine it, two calibrations are necessary. The purpose of this work was to develop a calibration methodology that can be used to convert signal from the detector to D independently on calibration performed at Heavy Ion Medical Accelerator facility in Chiba, Japan.
- MeSH
- absorpce radiace MeSH
- design vybavení MeSH
- kalibrace MeSH
- kosmické záření * MeSH
- křemík MeSH
- letadla přístrojové vybavení MeSH
- lidé MeSH
- metoda Monte Carlo MeSH
- monitorování radiace přístrojové vybavení MeSH
- nadmořská výška MeSH
- neutrony MeSH
- polovodiče MeSH
- pracovní expozice analýza normy MeSH
- radiační expozice MeSH
- radionuklidy MeSH
- sluneční aktivita MeSH
- těžké ionty MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Track-etched detectors (TED) have been used as linear energy transfer (LET) spectrometers in heavy ion beams for many years. LET spectra and depth-dose distribution of a carbon ion beam were measured behind polymethylmethacrylate degraders at Heavy Ion Medical Accelerator in Chiba, Japan. The measurements were performed along monoenergetic beam with energy 290 MeV u(-1) in different positions: (1) at beam extraction area, (2) at beginning, (3) maximum and (4) behind the Bragg peak region (0, 117, 147 and 151 mm of water-equivalent depth, respectively). The LET spectra inside and outside of the primary ion beam have been evaluated. TED record only heavy charged particles with LET above 8-10 keV µm(-1), while electrons and ions with lower LET are not detected. The Geant4 simulation toolkit version 4.9.6.P01 has been used to estimate the contribution of non-detected particles to absorbed dose. Presented results demonstrate the applicability of TED for microdosimetry measurements in therapeutic carbon ion beams.
- MeSH
- částice - urychlovače přístrojové vybavení MeSH
- dávka záření MeSH
- design vybavení MeSH
- elektrony MeSH
- kalibrace MeSH
- lineární přenos energie účinky záření MeSH
- mikrotechnologie metody MeSH
- počítačová simulace MeSH
- polymethylmethakrylát chemie MeSH
- radiometrie přístrojové vybavení MeSH
- těžké ionty * MeSH
- uhlík * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Conventional radiotherapy with X- and gamma-rays is one of the common and effective treatments of cancer. High energy hadrons, i.e., charged particles like protons and (12)C ions, due to their specific physics and radiobiological advantages are increasingly used. In this study, effectiveness of different radiation types is evaluated on the radio-resistant human HTB140 melanoma cells. The cells were irradiated with gamma-rays, the 62 MeV protons at the Bragg peak and in the middle of the spread-out Bragg peak (SOBP), as well as with the 62 MeV/u (12)C ions. The doses ranged from 2 to 24 Gy. Cell survival and proliferation were assessed 7 days after irradiation, whereas apoptosis was evaluated after 48 h. The acquired results confirmed the high radio-resistance of cells, showing better effectiveness of protons than gamma-rays. The best efficiency was obtained with (12)C ions due to higher linear energy transfer. All analyzed radiation qualities reduced cell proliferation. The highest proliferation was detected for (12)C ions because of their large killing capacity followed by small induction of reparable lesions. This enabled unharmed cells to preserve proliferative activity. Irradiations with protons and (12)C ions revealed similar moderate pro-apoptotic ability that is in agreement with the level of cellular radio-resistance.
- MeSH
- financování organizované MeSH
- ionizující záření klasifikace MeSH
- lidé MeSH
- melanom radioterapie MeSH
- nádorové buněčné linie účinky záření MeSH
- proliferace buněk účinky léků účinky záření MeSH
- protony MeSH
- radiační účinky MeSH
- radioterapie metody využití MeSH
- statistika jako téma MeSH
- těžké ionty terapeutické užití MeSH
- tolerance záření účinky záření MeSH
- uhlík MeSH
- viabilita buněk účinky záření MeSH
- vysokoenergetická radioterapie metody využití MeSH
- Check Tag
- lidé MeSH
Five various materials employed as track-etched detectors (TEDs) were exposed in beams of carbon ions with energy 290 MeV. u(-1) in the HIMAC-BIO facility in Japan. The exposures were performed behind various types of polymethyl methacrylate shielding. The beam had two possible set-ups--monoenergetic set-up and modulated spread-out Bragg peak set-up. All used TEDs are polyallyl diglycol carbonates (PADCs): Page from Mouldings (Pershore) Ltd, Tastrak from Track Analysis Systems Ltd, both from the UK; USF4 from American Technical Plastics from the USA and two products of Japan Fukuvi Chemical Industry Co., Ltd--TD1 and Baryotrak. Spectra of linear energy transfer and depth-dose distributions were obtained. Besides, differences among PADCs are discussed.
Active mobile dosimetry unit (Liulin), passive plastic nuclear track detectors (PNTD) and thermoluminescent detectors (TLD) were exposed in a C290 MeV/n beam at HIMAC-BIO (NIRS, Japan). Two different types of beam configuration were used--monoenergetic beam (MONO) and spread-out Bragg peak (SOBP); the detectors were placed at several depths from the entrance up to the depths behind the Bragg peak. Relative response of TLDs in beams has been studied as a function of the depth, and it was re-proved that it can depend on the linear energy transfer (LET). Liulin measures energy deposition in Si; the spectra of energy deposited in Si can be transformed to the spectra of lineal energy or LET. PNTDs are able to determine the LET of registered particles directly. The limitation of both methods is in the range in which they can determine the LET-Liulin is able to measure perpendicularly incident charged particles up to ∼35 keV/µm (in water), PNTD can measure from ∼7 to 400 keV/µm, independently of the registration angle. The results from both methods are compared and combined for both beams' configuration, and a good agreement is observed.
- MeSH
- analýza selhání vybavení MeSH
- částice - urychlovače přístrojové vybavení MeSH
- design vybavení MeSH
- lineární přenos energie MeSH
- radiometrie přístrojové vybavení MeSH
- těžké ionty terapeutické užití MeSH
- Publikační typ
- časopisecké články MeSH
- hodnotící studie MeSH
- srovnávací studie MeSH
- Geografické názvy
- Japonsko MeSH
