BACKGROUND: FLASH radiotherapy necessitates the development of advanced Quality Assurance methods and detectors for accurate monitoring of the radiation field. This study introduces enhanced time-resolution detection systems and methods used to measure the delivered number of pulses, investigate temporal structure of individual pulses and dose-per-pulse (DPP) based on secondary radiation particles produced in the experimental room. METHODS: A 20 MeV electron beam generated from a linear accelerator (LINAC) was delivered to a water phantom. Ultra-high dose-per-pulse electron beams were used with a dose-per-pulse ranging from ̴ 1 Gy to over 7 Gy. The pulse lengths ranged from 1.18 μs to 2.88 μs at a pulse rate frequency of 5 Hz. A semiconductor pixel detector Timepix3 was used to track single secondary particles. Measurements were performed in the air, while the detector was positioned out-of-field at a lateral distance of 200 cm parallel with the LINAC exit window. The dose deposited was measured along with the pulse length and the nanostructure of the pulse. RESULTS: The time of arrival (ToA) of single particles was measured with a resolution of 1.56 ns, while the deposited energy was measured with a resolution of several keV based on the Time over Threshold (ToT) value. The pulse count measured by the Timepix3 detector corresponded with the delivered values, which were measured using an in-flange integrating current transformer (ICT). A linear response (R2 = 0.999) was established between the delivered beam current and the measured dose at the detector position (orders of nGy). The difference between the average measured and delivered pulse length was ∼0.003(30) μs. CONCLUSION: This simple non-invasive method exhibits no limitations on the delivered DPP within the range used during this investigation.
Úvod: Práce na pracovištích nukleární medicíny představuje pracovní činnosti, při kterých dochází k expozici ionizujícím zářením. Expozice může být ovlivněna nejen druhem aplikovaného radiofarmaka a jeho aktivitou, ale i způsobem aplikace. Metoda: Práce sleduje a hodnotí výsledky osobní dozimetrie lékařů na pracovišti Oddělení nukleární medicíny Masarykova onkologického ústavu v Brně ovlivněné instrumentací pro aplikaci radiofarmak. Výsledky: Využití instrumentace k aplikaci radiofarmak umožňuje redukci profesního ozáření aplikujících lékařů o více než 90 % v prstové a celotělové dozimetrii. Závěr: Na základě našich zkušeností s instrumentací v nukleární medicíně lze tento princip radiační ochrany (RO) označit za velmi účinný nástroj optimalizace RO také při aplikaci radiofarmak. Takto optimalizovanou RO dochází k posílení bezpečnostních prvků ve vztahu k aplikujícím pracovníkům, čímž se vytváří prostor k možnému navyšování provozu a zvyšování dostupnosti péče v oblasti nukleární medicíny ve vztahu k pacientům.
Introduction: Exposition to radiation is necessarily connected with working at departments of nuclear medicine. The exposure can be influenced by the type of a radiopharmaceutical, its activity and the way of application. Method: This paper analyses the personal dosimetry of physicians at the Department of Nuclear Medicine, Masaryk Memorial Cancer Institute in Brno and evaluates the influence of instrumental application of radiopharmaceuticals on radiation exposure. Results: Use of instrumentation for application of radiopharmaceuticals results in reduction of occupational exposure of physicians by more than 90 % in ring and whole-body dosimetry. Conclusion: Based on our experience with instrumentation at department of nuclear medicine, this principle of radiation protection (RP) has proved to be a very effective tool of RP optimization in application of radiopharmaceuticals. Such optimization of RP reinforces safety elements in relation to the applicating staff, therefore enabling the increase in number of examined patients and increase in availability of nuclear medicine care in relation of patients.
- MeSH
- bezpečnost MeSH
- dávka záření MeSH
- infuzní pumpy * klasifikace MeSH
- ionizující záření MeSH
- lidé MeSH
- nemoci z povolání prevence a kontrola MeSH
- nukleární lékařství metody přístrojové vybavení statistika a číselné údaje MeSH
- radiační ochrana metody přístrojové vybavení MeSH
- radiofarmaka * aplikace a dávkování MeSH
- radiometrie metody přístrojové vybavení škodlivé účinky statistika a číselné údaje MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Objective.There is an increasing interest in calculating and measuring linear energy transfer (LET) spectra in particle therapy in order to assess their impact in biological terms. As such, the accuracy of the particle fluence energy spectra becomes paramount. This study focuses on quantifying energy depositions of distinct proton, helium, carbon, and oxygen ion beams using a silicon pixel detector developed at CERN to determine LET spectra in silicon.Approach.While detection systems have been investigated in this pursuit, the scarcity of detectors capable of providing per-ion data with high spatial and temporal resolution remains an issue. This gap is where silicon pixel detector technology steps in, enabling online tracking of single-ion energy deposition. The used detector consisted of a 300μm thick silicon sensor operated in partial depletion.Main results.During post-processing, artifacts in the acquired signals were identified and methods for their corrections were developed. Subsequently, a correlation between measured and Monte Carlo-based simulated energy deposition distributions was performed, relying on a two-step recalibration approach based on linear and saturating exponential models. Despite the observed saturation effects, deviations were confined below 7% across the entire investigated range of track-averaged LET values in silicon from 0.77 keVμm-1to 93.16 keVμm-1.Significance.Simulated and measured mean energy depositions were found to be aligned within 7%, after applying artifact corrections. This extends the range of accessible LET spectra in silicon to clinically relevant values and validates the accuracy and reliability of the measurements. These findings pave the way towards LET-based dosimetry through an approach to translate these measurements to LET spectra in water. This will be addressed in a future study, extending functionality of treatment planning systems into clinical routine, with the potential of providing ion-beam therapy of utmost precision to cancer patients.
- MeSH
- křemík MeSH
- lineární přenos energie * MeSH
- metoda Monte Carlo MeSH
- radiometrie přístrojové vybavení MeSH
- Publikační typ
- časopisecké články MeSH
Kontroly kvality měřidel aktivity jsou nedílnou součástí rutinní praxe na pracovištích nukleární medicíny. Technický způsob jejich provádění je do jisté míry variabilní. Námi navržený způsob vychází z požadavků klinické praxe a z potřeby způsob provádění kontrol co nejvíce zefektivnit. Popisované technické řešení umožňuje přímé vyčtení dat z měřiče aktivity do počítače (tabletu, chytrého telefonu a podobně) a jejich následné okamžité zpracování. Pro komunikaci mezi měřicím přístrojem a počítačem byla zkonstruována převodní jednotka využívající technologii Bluetooth. Práce s ionizační komorou je řízena přes makro psané ve VBA (Excel). Data načtená do Excelu jsou následně zpracována a vyhodnocena dle požadavků uživatele. Předkládané řešení je levné a snadno modifikovatelné, jeho velkou výhodou je využívání MS Office, které je v současné době snadno dostupné všem uživatelům na pracovištích nukleární medicíny.
Quality control tests of dose calibrators are an integral part of routine practice in all departments of nuclear medicine. They should be carried out regularly to ensure their optimum performance at all times and to determine the rate and extend of any deterioration in time. However, when there is no additional software purchased for these particular purposes, data collecting, and subsequent processing could sometimes be a tedious and time-consuming process. Based on the requirements of clinical practice an efficient method was developed to facilitate data handling. The described technical solution enables direct reading of data from the dose calibrator to a computer (tablet, smartphone, etc.) and their subsequent immediate processing. A conversion unit using Bluetooth technology was designed for communication between the measuring device and the computer. Communication with the ionization chamber is controlled by a macro written in VBA (Visual basic for applications). The data loaded into Excel are subsequently processed and evaluated according to the user's requirements. The presented solution is cheap and easy to modify, its big advantage is the compatibility with MS Office, which is currently easily accessible to all users at nuclear medicine workplaces.
Úvod: V návrhu doporučení SÚJB jsou pro měřidla aktivity předepsány tyto zkoušky zajištění kvality: pozadí, krátkodobá stabilita, dlouhodobá stabilita, linearita, geometrická účinnost (objemová závislost). U zkoušky linearity systému je v doporučení jen metoda založená na rozpadu zdroje nicméně AtomLab 500 obsahuje vestavěné testy linearity jak pro tuto metodu, tak i pro metodou s atenuačními trubicemi (lineátorem). Účelem článku je porovnání obou vestavěných metod a poukázání na vzájemné výhody a nevýhody. Metoda: Automatizovaná zkouška linearity založená na rozpadu zdroje, a zkouška linearity s atenuačními trubicemi (lineátorem) podle pokynů výrobce AtomLabu 500 (Biodex). Výchozí aktivity 99mTc u první metody byly 13,08 GBq a dodatečná 37,4 MBq, intervaly měření 6 h a ukončení testu pod 0,37 MBq, u druhé metody byly aktivity 99mTc pro 2 různé kombinace trubic lineátoru 11,53 GBq a 1811 MBq a provedení testu do 6 minut. Naměřená data byla vyhodnocena pomocí software měřiče aktivity (grafy, tabulky, odchylky od linearity – přípustné jsou ±5 %). Výsledky: Tabulky a semilogaritmické grafy s naměřenými hodnotami zkoušky linearity založené na rozpadu zdroje pro dvě výchozí aktivity (druhá nízká byla dodatečná, viz dále) a tabulky s hodnotami zkoušky linearity s lineátorem pro dvě aktivity a vypočtenými odchylkami od linearity systému. Test s druhou nízkou aktivitou (37,4 MBq 99mTc) u první metody byl doplněn kvůli nevyhovující poslední hodnotě testu s vysokou aktivitou (13,08 GBq 99mTc) – přístroj celkově prošel. Závěr: Test linearity prováděný u AtomLabu 500 dle pokynů výrobce 1× za 3 měsíce se zkracuje z původních 3–4 d u metody založené na rozpadu zdroje na zhruba 25 min (i s přípravou vzorků) u metody s lineátorem a přístroj není zbytečně blokován. Nevýhodou je nutnost kalibrace lineátoru před jeho 1. použitím, po výměně, poškození, po zásahu do přístroje a prokázání linearity systému výchozí metodou založenou na rozpadu zdroje před započetím využívání metody s lineátorem.
Introduction: In the draft recommendation of the State Office for Nuclear Safety (SÚJB) the following quality assurance tests are prescribed for radionuclide calibrators: background, short-term stability, long-term stability, linearity, geometric efficiency (volume dependence). For the system linearity test, only the method based on source decay is recommended, however AtomLab 500 includes built-in linearity tests for both this method and the method with attenuation tubes (lineator). The purpose of the article is to compare both built-in methods and point out mutual advantages and disadvantages. Method: Automated linearity test based on source decay and linearity test with attenuation tubes (lineator) according to the manufacturer's instructions AtomLab 500 (Biodex). Initial 99mTc activities for the first method were 13.08 GBq and additional 37.4 MBq, measurement intervals of 6 h and test completion below 0.37 MBq, for the second method, 99mTc activities for 2 different combinations of lineator tubes were 11.53 GBq and 1811 MBq and test execution within 6 minutes. The measured data were evaluated using radionuclide calibrator software (graphs, tables, deviations from linearity – ±5 % are allowed). Results: Tables and semilogarithmic graphs of measured linearity test values based on source decay for two default activities (second low one was additional, see below) and tables of linearity test values with lineator for two activities and calculated deviations from system linearity. The test with the second low activity (37.4 MBq 99mTc) in the first method was supplemented due to the unsatisfactory last value of the test with high activity (13.08 GBq 99mTc) – the device passed overall. Conclusion: The linearity test performed with the AtomLab 500 according to the manufacturer's instructions once every 3 months is shortened from the original 3–4 d for the method based on the decay of the source to approximately 25 min (including sample preparation) for the lineator method and the device is not blocked unnecessarily. The disadvantage is the necessity of calibrating the lineator before its 1st use, after replacement, damage, after intervention in the device and proving the linearity of the system by the default method based on the decay of the source before starting to use the lineator method.
Neutron detection using nuclear emulsions can offer an alternative in personal dosimetry. The production of emulsions and their quality have to be well controlled with respect to their application in dosimetry. Nuclear emulsions consist mainly of gelatin and silver halide. Gelatin contains a significant amount of hydrogen, which can be used for fast neutron detection. The addition of B-10 in the emulsion is convenient for thermal neutron detection. In this paper, standard nuclear emulsions BR-2 and nuclear emulsions BR-2 enriched with boron produced at the Slavich Company, Russia, were applied for evaluation of fast and thermal neutron fluences. The results were obtained by calculation from the presumed emulsion composition without prior calibration. Evidence that nuclear emulsions used in the experiment are suitable for neutron dosimetry is provided.
- MeSH
- bor chemie MeSH
- bromidy chemie MeSH
- emulze * MeSH
- fantomy radiodiagnostické MeSH
- helium analýza MeSH
- kalibrace MeSH
- lithium analýza MeSH
- neutrony * MeSH
- počítačové zpracování obrazu MeSH
- radiometrie přístrojové vybavení metody MeSH
- rychlé neutrony * MeSH
- sloučeniny stříbra chemie MeSH
- vodík chemie MeSH
- želatina chemie MeSH
- Publikační typ
- časopisecké články MeSH
Linearity of response belongs to fundamental characteristics of neutron detection systems. Research reactors are valuable tools for neutron detector non-linearity studies as they offer a wide range of neutron fluxes. For neutron detection systems working in pulse mode they enable to characterise detector response non-linearity from some hundreds of cps up to the maximum reachable count rates. The paper presents comparison of two methods for neutron pulse-mode detector non-linearity characterisation using VR-1 zero power reactor: (1) comparative method utilising the comparison of studied pulse-mode detection system with a response of gamma compensated ionisation chamber working in current mode, and (2) kinetics method utilising the asymptotic exponential power rise after positive reactivity insertion as a source of information on true signal. Further several approaches for dead time determination based on theoretical formulae describing paralysable and non-paralysable dead time behaviour of detectors were studied and their usability to characterise the count-rate dependent detector response was analysed.
- MeSH
- algoritmy * MeSH
- lidé MeSH
- metoda Monte Carlo MeSH
- neutrony * MeSH
- radiometrie přístrojové vybavení MeSH
- záření gama MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
Unique 3D tomography apparatus was built and successfully tested in Research Centre Rez. The apparatus allows three-dimensional view into the interior of low-dimension radioactive samples with a diameter up to several tens of millimeters with a betterresolution then 1 mm3 and is designed to detect domains with different levels of radioactivity. Structural inhomogeneities such as cavities, cracks or regions with different chemical composition can be detected using this equipment. The SPECT scanner has been successfully tested on several samples composed of a 3-mm radionuclide source located eccentrically within homogeneous steel bushings. To detect fine cracks inside a small sample, an ultrafine scan of the sample was carried out in the course of 24 hours with a 0.5-mm longitudinal and transverse step and 18° angular step. The exact location and orientation of a fine crack artificially formed inside a sample has been detected.
- MeSH
- algoritmy MeSH
- difuze MeSH
- geologie MeSH
- jednofotonová emisní výpočetní tomografie * MeSH
- oxid křemičitý MeSH
- počítačové zpracování obrazu metody MeSH
- poréznost MeSH
- radioizotopy kobaltu MeSH
- radiometrie přístrojové vybavení metody MeSH
- radon MeSH
- scintilace - počítání MeSH
- software MeSH
- teoretické modely MeSH
- wolfram MeSH
- záření gama MeSH
- zobrazování trojrozměrné * MeSH
- Publikační typ
- časopisecké články MeSH
Mobile phones and common chip cards are very widespread items that almost everyone owns. They contain some radiation-sensitive materials that can be used for dosimetry based on stimulated luminescence. We investigated and compared reproducibility, dose response and fading of luminescence signal for the particular materials. Subsequently, we performed an experiment of a dose reconstruction using mobile phones and chip cards, which were fixed to a slab phantom and irradiated by a 137Cs radiation source in our laboratory. Doses obtained were compared with reference values. The materials investigated can be used for dosimetry in cases of serious radiation accidents or malevolent acts with radioactive materials, when it is extremely important to identify as quickly as possible individuals who received high-radiation doses.
- MeSH
- dávka záření MeSH
- design vybavení MeSH
- fantomy radiodiagnostické MeSH
- kalibrace MeSH
- luminiscence * MeSH
- mobilní telefon * MeSH
- radioizotopy cesia analýza MeSH
- radiometrie přístrojové vybavení metody MeSH
- reprodukovatelnost výsledků MeSH
- teplota MeSH
- termoluminiscenční dozimetrie MeSH
- únik radioaktivních látek * MeSH
- vztah dávky záření a odpovědi MeSH
- Publikační typ
- časopisecké články MeSH
