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Because of the unique characteristics of polymer gel dosimeters, it appears that these gels might offer a reliable method for measuring absorbed radiation dose from various radiotherapy techniques, such as BNCT. In this study, the ability of NIPAM polymer gel to record the dose distribution from the BNCT treatment modality was evaluated by simulating the clinical conditions for treatment of shallow tumors. In this regards, two polymethyl methacrylate (PMMA) cylinder phantoms, measuring 8 cm in diameter and 6 cm in height with a wall thickness of 5 mm, were used for irradiating the gel in front of the BNCT beam of the Tehran Research Reactor (TRR). One of the phantoms was filled by only NIPAM gel prepared by standard formulation and the other one containing about 20 cc NIPAM gel with 30 ppm of 10 B which was embedded inside the standard gel, with no separating layer, at a depth of 1 cm from the phantom wall. From the results, 18% increased dose was recorded in the area that was loaded the 10 B doped gel in comparison with the pure NIPAM gel. It can be concluded that NIPAM gel has the potential to be used in verification of BNCT treatment planning.

In head computed tomography, radiation upon the eye lens (as an organ with high radiosensitivity) may cause lenticular opacity and cataracts. Therefore, quantitative dose assessment due to exposure of the eye lens and surrounding tissue is a matter of concern. For this purpose, an accurate eye model with realistic geometry and shape, in which different eye substructures are considered, is needed. To calculate the absorbed radiation dose of visual organs during head computed tomography scans, in this study, an existing sophisticated eye model was inserted at the related location in the head of the reference adult male phantom recommended by the International Commission on Radiological Protection (ICRP). Then absorbed doses and distributions of energy deposition in different parts of this eye model were calculated and compared with those based on a previous simple eye model. All calculations were done using the Monte Carlo code MCNP4C for tube voltages of 80, 100, 120 and 140 kVp. In spite of the similarity of total dose to the eye lens for both eye models, the dose delivered to the sensitive zone, which plays an important role in the induction of cataracts, was on average 3% higher for the sophisticated model as compared to the simple model. By increasing the tube voltage, differences between the total dose to the eye lens between the two phantoms decrease to 1%. Due to this level of agreement, use of the sophisticated eye model for patient dosimetry is not necessary. However, it still helps for an estimation of doses received by different eye substructures separately.

The behavior of radiation-induced fixed oxide traps and radiation-induced switching traps near and at Si/SiO 2 interface during gamma-ray irradiation up to 50 Gy and post-irradiation annealing at room temperature has been investigated. These processes lead to threshold voltage shift, Δ V T , which is dosimetric parameter employed in total absorbed radiation dose determination. Irradiation was performed with gate bias from 0 to 5 V and annealing was performed without gate bias. The midgap-subthreshold technique was used to separate fixed traps and switching traps which for p-channel MOSFETs contribute to Δ V T in the same direction. It was shown that the increase in gate bias lead to the increase in fixed oxide traps density and switching traps density, what further increases Δ V T for the same radiation dose. The density of fixed traps created during irradiation is higher than the switching traps density. Post irradiation annealing at room temperature without gate bias, for 100 days period, lead to relatively small decrease in Δ V T , what is a consequence of both, decrease in fixed oxide traps density and increase in switching traps density.

High-Z nanoparticles can increase the absorbed radiation dose if they are accumulated in tumor cells. The quantitative measure of this radiosensitization effect is the dose enhancement factor (DEF), that is, the ratio of the doses absorbed in the presence and in the absence of nanoparticles. In the present work, the values of the dose enhancement factors of Ta2O5, HfO2, and CeO2 ceramic nanoparticles were calculated analytically for monochromatic radiation of the X-ray energy range (1–180 keV) and for low-energy sources for brachytherapy: 103Pd (mean energy, 20.6 keV), 125I (26.7 keV), and 131Cs (30.4 keV). For all types of nanoparticles in the concentration of 5 mg/mL, the values of the dose enhancement factor were high both for monochromatic radiation and for brachytherapy sources. The highest DEF values of ~1.7 were obtained for nanoparticles of tantalum oxide. For brachytherapy sources, the highest dose enhancement factors (1.48 to 1.67) were obtained for Ta2O5 and HfO2 nanoparticles. These results confirm that ceramic nanoparticles are promising dose modifying agents for radiotherapy.

Background: Hysterosalpingography (HSG) is an indispensable tool for diagnosing infertility in females. The procedure exposes female reproductive organs to ionizing radiation as the genitals are irradiated during the process. Investigating patient absorbed dose during the procedures is essential for effective radiological protection of the patient. Objective: This study aims to investigate the radiation dose received by patient during HSG examination in the study environment in order to enhance optimization of procedures and the associated dose, thereby minimizing radiation risks. Material and Methods: The prospective pilot study, was conducted in four tertiary healthcare institutions in Southwest Nigeria. Thermoluminescence dosimeter (TLD 100) was used to determine the Entrance Surface Dose (ESD) of 80 patients presented for HSG investigation. The corresponding effective dose, ovary, uterus and urinary bladder doses were evaluated using PCXMC software. Results: The mean entrance surface doses (ESD) obtained from the four centers were 18.58±6.31 mGy, 15.18±2.27 mGy, 17.44±3.43 mGy and 34.24±11.98 mGy for SW1, SW2, SW3 and SW4 centers, respectively. The corresponding mean of effective doses were 1.54±0.63 mSv, 1.24±0.28 mSv, 1.41±0.30 mSv and 2.53±0.94 mSv for SW1, SW2, SW3 and SW4 centers, respectively. The resulting mean doses to the ovary, urinary bladder and uterus were also presented. Conclusion: The results obtained in general are comparable with international standards. It was, however, recommended that study centers with high doses should conduct dose audit in order to enhance patient safety.

We present the first reported use of a CMOS Single Photon Avalanche Diode (SPAD) arrays for the detection of high energy photons (X-rays), utilizing a 3D-stacked backside illuminated (BSI) SPAD image sensor, and cabinet biological X-ray irradiator. We detected photon peak energies from 30 to 120 keV, and an increase in SPAD bias voltage results in higher relative average counts per pixel. Furthermore, after an absorbed radiation dose of 3.75 Mrad, the difference in DCR was found to not be statistically significant, with a calculated two-sided P-value of 0.787. This unveils new applications in X-ray detection.

Metal implants not only deteriorate image quality, but also increase radiation exposure. The purpose of this study was to evaluate the effect of metal hip prosthesis on absorbed radiation dose and assess the efficacy of organ dose modulation (ODM) and metal artifact reduction (MAR) protocols on dose reduction. An anthropomorphic phantom was scanned with and without bilateral metal hip prostheses, and surface and deep level radiation doses were measured at the abdomen and pelvis. Finally, the absorbed radiation doses at pelvic and abdominal cavities in the reference, ODM, and two MAR scans (Gemstone spectral imaging, GE) were compared. The Mann Whitney-U test and Kruskal-Wallis test were performed to compare the volume CT dose index (CTDIvol) and mean absorbed radiation doses. Unilateral and bilateral metal hip prostheses increased CTDIVOL by 14.4% and 30.5%, respectively. MAR protocols decreased absorbed radiation doses in the pelvis. MAR showed the most significant dose reduction in the deep pelvic cavity followed by ODM. However, MAR protocols increased absorbed radiation doses in the upper abdomen. ODM significantly reduced absorbed radiation in the pelvis and abdomen. In conclusion, metal hip implants increased radiation doses in abdominopelvic CT scans. MAR and ODM techniques reduced absorbed radiation dose in abdominopelvic CT scans with metal hip prostheses.

Computed Tomography Perfusion (CTP) imaging is a cost-effective and fast approach to provide diagnostic images for acute stroke treatment. Its cine scanning mode allows the visualization of anatomic brain structures and blood flow; however, it requires contrast agent injection and continuous CT scanning over an extended time. In fact, the accumulative radiation dose to patients will increase health risks such as skin irritation, hair loss, cataract formation, and even cancer. Solutions for reducing radiation exposure include reducing the tube current and/or shortening the X-ray radiation exposure time. However, images scanned at lower tube currents are usually accompanied by higher levels of noise and artifacts. On the other hand, shorter X-ray radiation exposure time with longer scanning intervals will lead to image information that is insufficient to capture the blood flow dynamics between frames. Thus, it is critical for us to seek a solution that can preserve the image quality when the tube current and the temporal frequency are both low. We propose STIR-Net in this paper, an end-to-end spatial-temporal convolutional neural network structure, which exploits multi-directional automatic feature extraction and image reconstruction schema to recover high-quality CT slices effectively. With the inputs of low-dose and low-resolution patches at different cross-sections of the spatio-temporal data, STIR-Net blends the features from both spatial and temporal domains to reconstruct high-quality CT volumes. In this study, we finalize extensive experiments to appraise the image restoration performance at different levels of tube current and spatial and temporal resolution scales.The results demonstrate the capability of our STIR-Net to restore high-quality scans at as low as 11% of absorbed radiation dose of the current imaging protocol, yielding an average of 10% improvement for perfusion maps compared to the patch-based log likelihood method.

Introduction: In this study, organ radiation doses were calculated for the renal agent 99mTc-DTPA in children. Bio-kinetic energy of 99mTc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques. Material and Methods: In this applied research, fourteen children patients (6 males and 8 females) were imaged using a series of planar and SPECT images after injecting with technetium-99m diethylenetriaminepentaacetic acid (99mTc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups. Results: Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were 213.5±47.8, 12.97±6.23, 12.0±2.5, 4.29±1.47, and 3.31±0.96, respectively. Furthermore, the mean effective dose was 17.5±3.7 µSv/ MBq. There was not any significant difference in the mean absorbed dose of the two groups. Conclusion: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with 99mTc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended. Citation: Ebrahimnejad Gorji K, Abedi Firouzjah R, Khanzadeh F, Abdi-Goushbolagh N, Banaei A, Ataei Gh. Estimating the Absorbed Dose of Organs in Pediatric Imaging of 99mTc-DTPA Radiopharmaceutical using MIRDOSE Software. J Biomed Phys Eng. 2019;9(3):285-294. https://doi.org/10.31661/jbpe.v0i0.984.

In order to track “small dose effect” leading to stabilization of RADFETs with 1 μm thick oxide fabricated at Tyndall National Institute, Cork, Ireland irradiation was performed with gamma-rays in the radiation dose interval from 1 to 5 cGy, followed with room temperature annealing for the time of 28 days. Gate bias during irradiation was 0, 2.5 and 5 V. Threshold voltage shift Δ V T determined from transfer characteristics in saturation were followed during irradiation and annealing. It was shown that there is significant increase in Δ V T for 1 cGy radiation dose and those are 36.3, 43.3 mV and 45.7 mV for gate bias 0, 2.5 V and 5 V, respectively. For higher radiation doses Δ V T also increases, however, such increase is much lower. RADFETs fading at room temperature lead to permanent decrease in Δ V T and after 28 days the threshold voltage for devices is returned to virgin device value. Small dose effect is confirmed and radiation dose of at least 5 cGy is necessary for RADFET stabilization before their use in dosimetric application. After RADFETs stabilization they were irradiated in dose interval from 10 to 50 cGy with gate bias of 0, 2.5 and 5 V. It was shown that there is a linear dependence between Δ V T and absorbed radiation dose D , for gate bias during irradiation 0, 2.5 and 5 V. Defects responsible for threshold voltage shift, formed during irradiation as well as their neutralization/compensation during annealing, are also discussed.

Polypropylene (PP) is used for different sectors of the industry and in consequence produces a large amount of waste discarded at landfills causing serious environmental impacts. Controlled degradation of PP can be achieved by exposing the polymers to defined parameters, such as absorbed radiation dose, weather, oxygen, etc. The aim of this study was to compare two methods of accelerated degradation: gamma irradiation of PP 20 kGy and the incorporation of the commercial pro-degradant d2w® (1 wt%) in PP. Dumbbell samples were manufactured by the injection process and exposed to the environment aging for 90 days. Structural changes in PP macromolecules are created upon exposure to ionizing radiation such as main chain scission, crosslinking and peroxidation (in presence of air). Differential scanning calorimetry (DSC), thermogravimetric analysis (TG), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), X-ray fluorescence, Fourier-transformed infrared spectroscopy (FTIR) and mechanical tests characterized the samples. The samples previously irradiated, PP 20 kGy, after natural aging showed higher oxidation and presence of surface cracks than the PP d2w®. They also showed presence of carbonyl groups and decrease of melting temperature corroborating with oxo-degradation.

This study assessed the in vivo distribution of 11C-nicotine and the absorbed radiation dose from whole-body 11C-nicotine PET imaging of 11 healthy (5 male and 6 female) subjects. Methods: After an initial CT attenuation scan, 11C-nicotine was administered via intravenous injection. A dynamic PET scan was acquired for 90 s with the brain in the field of view, followed by a series of 13 whole-body PET scans acquired over a 90-min period. Regions of interest were drawn over organs visible in the reconstructed PET images. Time-activity curves were generated, and the residence times were calculated. The absorbed radiation dose for the whole body was calculated by entering the residence time in OLINDA/EXM 1.0 software to model the equivalent organ dose and the effective dose for a 70-kg man. Results: The mean residence times for 11C-nicotine in the liver, red marrow, brain, and lungs were 0.048 ± 0.010, 0.031 ± 0.005, 0.021 ± 0.004, and 0.020 ± 0.005 h, respectively. The mean effective dose for 11C-nicotine was 5.44 ± 0.67 μSv/MBq. The organs receiving the highest absorbed dose from the 11C-nicotine injection were the urinary bladder wall (14.68 ± 8.70 μSv/MBq), kidneys (9.56 ± 2.46 μSv/MBq), liver (8.94 ± 1.67 μSv/MBq), and spleen (9.49 ± 3.89 μSv/MBq). The renal and hepatobiliary systems were the major clearance and excretion routes for radioactivity. Conclusion: The estimated radiation dose from 11C-nicotine administration is relatively modest and would allow for multiple PET examinations on the same subject.

A study has been conducted with the goal of comparing the characteristics of TLD-K detectors based on sodium silicate ceramics to the characteristics of monocrystalline lithium fluoride detectors that contain traces of titanium and magnesium (TLD-100), as well as anion-defected aluminum oxide (TLD-500), which are widely used in thermoluminescent dosimetry. Because they are soil-equivalent, SiO2 detectors are well suited for measuring the absorbed radiation dose in soils. The results of the comparison indicate that TLD-K detectors are preferable to LiF detectors in environmental applications due to the better uniformity of the detector sensitivity in a batch, the wider range of measurable doses, and the lower threshold in determining small doses.

The higher energy and luminosity of future High Luminosity (HL) LHC, determines a significant increasing of the radiation background around the CMS subdetectors, and especially in the higher pseudorapidity region. Under such heavy conditions, the RPC (used in muon trigger) most probably could not operate effectively. GEM (Gas Electron Multiplier) detectors have been identified as a suitable technology to operate in the high radiation environment in that region and test at CMS will start in 2016. A monitoring system to control the absorbed radiation dose by the GEM under test is developed. Two types of sensors are used in it: RadFETs for total absorbed dose and p-i-n diodes for particle (proton and neutron) detection. The basic detector unit, called RADMON, contains two sensors of each type and can be installed at each GEM detector. The system has a modular structure, permitting to increase easily the number of controlled RADMONs: one module controls up to 12 RADMONs, organized in three group of four and communicates outside by RS 485 and CANBUS interfaces.

Objectives To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Background Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, antiscatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. Methods We used anthropomorphic phantoms (ages: newborn and 5 years old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies' Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20 cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. Results For the newborn and 5-year-old phantoms, respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20 cm increase in source-to-image-distance; −42% and −48% with addition of 1-inch periphery collimation; −31% and −46% with removal of the antiscatter grid. Compared with an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and fourfold (5 years old). Estimated cancer LAR from 30-min of posteroanterior fluoroscopy using optimized versus suboptimal imaging, respectively was 0.42% versus 1.23% (newborn female), 0.20% versus 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% versus 0.69% (5-year-old male). Conclusions Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. © 2016 Wiley Periodicals, Inc.

Background: 177Lu-octreotate is an effective treatment modality for patients with metastatic neuroendocrine tumors. The kidney is a critical dose-limiting organ in that modality. We investigated the absorbed doses in the kidney and compared whole kidney volume (WKV) and small (4 cm3) volume of the kidney (SV) methods. We also evaluated a new calculation method that was based on two single photon emission computed tomography/computed tomography (SPECT/CT) scans.Methods: Absorbed radiation doses in the kidneys were calculated for 24 patients with neuroendocrine tumors. All patients received four cycles of 177Lu-octreotate given at eight-week intervals with a mean activity of 7.1 GBq (range 3.28–8.79 GBq). Absorbed doses and half-lives were calculated by the WKV and SV methods. Dosimetry was determined for the cortex and medulla in the first treatment cycle.Results: The mean absorbed radiation dose was 0.44 ± 0.15 Gy/GBq for the WKV method and, 0.74 ± 0.28 Gy/GBq for the SV method. Three patients had...

The paper reports on the design of biological neutron shielding for IR-MPF100 plasma focus device which recently has been designed and constructed in plasma physics and nuclear fusion research institute. Plasma focus devices are known as pulsed intense sources of ionizing radiations such as hard X-ray and fast neutrons as a result of the formation of a hot dense plasma column then acceleration of energetic ions and electrons in the opposite directions. Therefore, taking into account a biological shield particularly for the operators of the PF device as radiation workers is crucial. Analytical calculations on the maximum permissible effective dose for radiation workers (for whole-body exposure) allow below 200 shots/year for IR-MPF100 operating at its nominal 115 kJ capacitor bank energy without any shielding wall. In order to decrease the personnel absorbed radiation dose and increase the maximum allowed shot per year the design considerations for a biological shield has been recognized using MCNP4C code. Our calculations was based on the effect of ordinary concrete, polyethylene mixed with 30 % natural boron and solid boric acid on the decrement of the absorbed dose. These calculations represent that using a double layer shield consists of 30 cm width of pure polyethylene as well as 10 cm lead, ends in appropriate decrement of the effective dose per shot from 0.1 mSv to 1.2 µSv, therefore increases the allowed usage of the device up to 15,600 annual shots.

Purpose: There is a need to rapidly triage individuals for absorbed radiation dose following a significant nuclear event. Since most exposed individuals will not have physical dosimeters, we are de...

This article presents the design results of the precision microcircuit of the instrumentation amplifier (IA) based on the fully differential difference op-amp (FDDA) and the double-channel low pass filter (LPF). It shows that the application of such IA leads to the high parameters of the sensor interface in the stability of output offset voltage (200uV oo n up to 1018 n/m2 and absorbed radiation dose D up to 1 Mrad. The results of the IA simulation designed on the base of radiation-hardened BiJFet technology (OJSC “Integral”, Minsk) are given.

Thoron (220 Rn) is a natural radioactive gas, tasteless, odourless, colourless, undetectable without proper equipment. This gas is carcinogenic, just like radon (222 Rn) but due to the short half-life (55.6s) and a small amount in the environment, its share in the absorbed radiation dose is often neglected. However, in areas rich in thorium (232Th), the radiation dose from the thoron can be much larger and quite significant. The problem is to measure the concentration of the thoron due to its short decay time as well as the fact that it is alpha-emitting as radon. An even greater challenge is to determine the emanation coefficient for the thoron. The method used in this experiment was developed by S.D. Kanse based on the work of D.J Greeman and adapted to the equipment used in Laboratory of Radiometric Expertise IFJ PAN. In the technique used to determine the thoron emanation coefficient, a closed loop system is used in which thoron is pushed out by means of a flow system from the sample and measured by a AlphaGuad DF2000 detector that is adapted to determine concentration of this gas. A sample of the material is placed between 2 filters in the geometry of the sandwich. This arrangement ensures that the thickness of the powder sample is significantly less than the length of the thoron diffusion, thus avoiding significant loss of the thoron due to intergranular absorption and facilitates the complete removal of this gas escaping from the powder. Using this technique, it is important to determine the concentration of 226Ra and the 232Th, since for the AlphaGuard detector, the ratio between thoron and radon should not exceed 5:1 for proper determination of the thoron concentration. Measurements of 226Ra and 232Th activity were carried out using gamma spectroscopy (HPGe detector). It was examined how the type of filter and grain size of sample affects the obtained results.

Sophisticated techniques employed in radiotherapy for irradiation of tumours require comprehensive dosimetry allowing for precise, high resolution measurements of radiation dose distribution in three dimensions and verification of treatment planning systems. Polymer gel dosimetry has been shown to be a unique technique for three-dimensional high resolution measurements of absorbed radiation dose distributions. If exposed to ionizing radiation, radical polymerisation and crosslinking of monomeric components take place in a 3D polymer gel dosimeter, leading to the formation of large polymeric structures that scatter visible light. This feature allows for optical observation of the effects of the absorbed dose and its distribution. Presently, magnetic resonance imaging is employed the most often for analysis of 3D polymer gel dosimeters. However, much attention is also being given to the development of optical computed tomography since this technique is hoped to serve as a substitute for expensive and not easily available magnetic resonance imaging. The optical scanner presented in this work consists of a laser diode, a scanning system and a signal detector. A 3D polymer gel dosimeter is measured in an immersion liquid in order to reduce deflection of the light from the dosimeter phantom. The very first results were obtained with the newly constructed scanner for PABIGnx 3D polymer gel dosimeter, which was inhomogeneously irradiated with 192Ir brachytherapy source. The results have been contrasted with those for magnetic resonance imaging and are presented in this work together with the description of the optical scanner. Currently, optimization of the optical scanner is performed.

Use of ionizing radiation (IR) in various industrial, medical and other applications can potentially increase the risk of medical, occupational or accidental human exposure. Additionally, in the event of a radiological or nuclear (R/N) incident, several tens of hundreds and thousands of people are likely to be exposed to IR. IR causes serious health effects including mortality from acute radiation syndrome and therefore it is imperative to determine the absorbed radiation dose, which will enable physicians in making an appropriate clinical 'life-saving' decision. The 'Dicentric Chromosome Assay (DCA)' is the gold standard for estimating the absorbed radiation dose but its performance is time consuming and laborious. Further, timely evaluation of dicentric chromosomes (DCs) for dose estimation in a large number of samples provides a bottleneck because of a limited number of trained personnel and a prolonged time for manual analysis. To circumvent some of these technical issues, we developed and optimized a miniaturized high throughput version of DCA (mini-DCA) in a 96-microtube matrix with bar-coded 1.4 ml tubes to enable the processing of a large number of samples. To increase the speed of DC analysis for radiation dose estimation, a semi-automated scoring was optimized using the Metafer DCScore algorithm. The accuracy of mini-DCA in dose estimation was verified and validated though comparison with conventional DCA performed in 15 ml conical tubes. The mini-DCA considerably reduced the sample processing time by a factor of 4 when compared to the conventional DCA. Further, the radiation doses estimated by mini-DCA using the triage mode of scoring (50 cells or 30 DCs) were similar to that of conventional DCA using 300-500 cells. The mini-DCA coupled with semi-automated DC scoring not only reduced the sample processing and analysis times by a factor of 4 but also enabled the processing of a large number of samples at once. Our mini-DCA method, once automated for high throughput robotic platforms, will be an effective radiological triage tool for mass casualty incidents.

Upotreba kompjuterizovane tomografije (CT) je veoma frekventna, kako u humanoj, tako i u veterinarskoj medicini. Imajući u vidu činjenicu da su doze zračenja koje pacijent primi prilikom CT pregleda višestruko veće od doza koje primi tokom konvencionalne rendgenografije, velika paţnja se posvećuje proceni opravdanosti ove vrste dijagnostičkog postupka i njegovoj optimizaciji, uz minimalno izlaganje pacijenata radijacionom opterećenju. Shodno tome, osnovni cilj ovog istraţivanja je podrazumevao ispitivanje korelacije izmeĎu apsorbovanih doza zračenja i stepena aktivnosti antioksidativnih enzima u pojedinim organima kunića nakon CT pregleda obavljenog pri različitim vrednosti napona i jačine struje u rendgenskoj cevi. Eksperiment je izvršen na 66 polno zrelih muţjaka novozelandskog belog kunića, rasporeĎenih u 11 eksperimentalnih grupa, sa po šest ţivotinja u svakoj. Kontrolne grupe kunića nisu izlagane zračenju već su ţrtvovane odmah (grupa NT), odnosno dva sata (grupa A1) i sedam dana (grupa A2) nakon primene anestezije koja je postignuta upotrebom ketamina i ksilazina. Ţivotinje iz preostalih osam grupa su, pre izlaganja x-zračenju, najpre anestezirane, kako bi se obezbedilo njihovo mirovanje tokom CT pregleda. Sva snimanja su izvršena pod sledećim uslovima: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17,9 mGy (I1 i I2 grupa); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25,2 mGy (II1 i II2 grupa); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29,8 mGy (III1 i III2 grupa) i U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42,1 mGy (IV1 i IV2 grupa). Ţivotinje iz I1, II1, III1 i IV1 grupe su bile ţrtvovane dva sata nakon snimanja, dok su kunići iz I2, II2, III2 i IV2 grupe ţrtvovani nakon sedam dana. Neposredno po ţrtvovanju obavljenom metodom dekapitacije, od svih ţivotinja je prikupljan biološki materijal (uzorci krvi eritrocita, mozga, pluća, srca, jetre, slezine, bubrega, tankog creva i semenika) u kojima je odreĎivana aktivnost sledećih antioksidativnih enzima: superoksid dismutaze (SOD), mangan superoksid dismutaze (MnSOD), bakar-cink superoksid dismutaze (CuZnSOD), katalaze (CAT), glutation peroksidaze (GSH-Px) i glutation reduktaze (GR). Izmerene aktivnosti antioksidativnih enzima u ispitivanim uzorcima su komparirane sa vrednostima asporbovanih doza koje su izračunate na predhodno konstruisanom voksel fantomu reprezentativnog kunića. S obzirom na činjenicu da eritrocite i tanko crevo nije moguće prikazati u voksel geometriji, stepen oksidativnih promena u ovim strukturama je poreĎen sa CTDIw vrednostima... Usage of computed tomography (CT) is very frequent, both in human and veterinary medicine. Bearing in mind that the radiation dose, that patient receive during CT examination, is several times higher than during conventional radiography, much attention is devoted to evaluate necessity of this diagnostic procedure and its optimization, along with the minimal exposure of patients to the radiation load. According to this, the main goal of these investigations was to explore a correlation between absorbed radiation doses and the degree of activity of antioxidant enzymes in rabbit organs following CT examination performed by different tube voltage and amperage values. Experiment was conducted on 66 mature male New Zealand rabbits divided in 11 groups, consisting of six animals each. Animals from the control groups (NT) were not irradiated and were sacrificed immediately after two hours (group A1) and seven days (group A2) following anesthesia induced by ketamine and xylasine. Animals from the remaining eight groups were anesthetized, prior to irradiation, to ensure still positioning during CT examination. All examinations were performed under the following conditions: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17.9 mGy (groups I1 and I2); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25.2 mGy (groups II1 and II2); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29.8 mGy (groups III1 and III2) and U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42.1 mGy (groups IV1 and IV2). Animals from the groups I1, II1, III1 and IV1 were sacrificed two hours following irradiation, while rabbits from the groups I2, II2, III2 and IV2 were sacrificed after seven days. Immediately after sacrifice, performed by decapitation method, organ samples were taken (blood – erythrocytes, brain, lungs, heart, liver, spleen, kidney, small intestine and testicles) for estimation of the following antioxidant enzyme activity: superoxide dismutase (SOD), Mn superoxide dismutase (MnSOD), Copper-Zinc superoxide dismutase CuZnSOD, catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR). Values, of the antioxidant enzyme activities in investigated samples, were then compared with values of the absorbed doses calculated on the previously constructed voxel phantom of the representative rabbit. According to the fact, that erythrocytes and small intestine can't be presented in voxel geometry, the degree of oxidative changes in these structures was compared to CTDIw values...

We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements.

Usage of computed tomography (CT) is very frequent, both in human and veterinary medicine. Bearing in mind that the radiation dose, that patient receive during CT examination, is several times higher than during conventional radiography, much attention is devoted to evaluate necessity of this diagnostic procedure and its optimization, along with the minimal exposure of patients to the radiation load. According to this, the main goal of these investigations was to explore a correlation between absorbed radiation doses and the degree of activity of antioxidant enzymes in rabbit organs following CT examination performed by different tube voltage and amperage values. Experiment was conducted on 66 mature male New Zealand rabbits divided in 11 groups, consisting of six animals each. Animals from the control groups (NT) were not irradiated and were sacrificed immediately after two hours (group A1) and seven days (group A2) following anesthesia induced by ketamine and xylasine. Animals from the remaining eight groups were anesthetized, prior to irradiation, to ensure still positioning during CT examination. All examinations were performed under the following conditions: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17.9 mGy (groups I1 and I2); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25.2 mGy (groups II1 and II2); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29.8 mGy (groups III1 and III2) and U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42.1 mGy (groups IV1 and IV2). Animals from the groups I1, II1, III1 and IV1 were sacrificed two hours following irradiation, while rabbits from the groups I2, II2, III2 and IV2 were sacrificed after seven days. Immediately after sacrifice, performed by decapitation method, organ samples were taken (blood – erythrocytes, brain, lungs, heart, liver, spleen, kidney, small intestine and testicles) for estimation of the following antioxidant enzyme activity: superoxide dismutase (SOD), Mn superoxide dismutase (MnSOD), Copper-Zinc superoxide dismutase CuZnSOD, catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR). Values, of the antioxidant enzyme activities in investigated samples, were then compared with values of the absorbed doses calculated on the previously constructed voxel phantom of the representative rabbit. According to the fact, that erythrocytes and small intestine can't be presented in voxel geometry, the degree of oxidative changes in these structures was compared to CTDIw values... Upotreba kompjuterizovane tomografije (CT) je veoma frekventna, kako u humanoj, tako i u veterinarskoj medicini. Imajući u vidu činjenicu da su doze zračenja koje pacijent primi prilikom CT pregleda višestruko veće od doza koje primi tokom konvencionalne rendgenografije, velika paţnja se posvećuje proceni opravdanosti ove vrste dijagnostičkog postupka i njegovoj optimizaciji, uz minimalno izlaganje pacijenata radijacionom opterećenju. Shodno tome, osnovni cilj ovog istraţivanja je podrazumevao ispitivanje korelacije izmeĎu apsorbovanih doza zračenja i stepena aktivnosti antioksidativnih enzima u pojedinim organima kunića nakon CT pregleda obavljenog pri različitim vrednosti napona i jačine struje u rendgenskoj cevi. Eksperiment je izvršen na 66 polno zrelih muţjaka novozelandskog belog kunića, rasporeĎenih u 11 eksperimentalnih grupa, sa po šest ţivotinja u svakoj. Kontrolne grupe kunića nisu izlagane zračenju već su ţrtvovane odmah (grupa NT), odnosno dva sata (grupa A1) i sedam dana (grupa A2) nakon primene anestezije koja je postignuta upotrebom ketamina i ksilazina. Ţivotinje iz preostalih osam grupa su, pre izlaganja x-zračenju, najpre anestezirane, kako bi se obezbedilo njihovo mirovanje tokom CT pregleda. Sva snimanja su izvršena pod sledećim uslovima: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17,9 mGy (I1 i I2 grupa); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25,2 mGy (II1 i II2 grupa); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29,8 mGy (III1 i III2 grupa) i U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42,1 mGy (IV1 i IV2 grupa). Ţivotinje iz I1, II1, III1 i IV1 grupe su bile ţrtvovane dva sata nakon snimanja, dok su kunići iz I2, II2, III2 i IV2 grupe ţrtvovani nakon sedam dana. Neposredno po ţrtvovanju obavljenom metodom dekapitacije, od svih ţivotinja je prikupljan biološki materijal (uzorci krvi eritrocita, mozga, pluća, srca, jetre, slezine, bubrega, tankog creva i semenika) u kojima je odreĎivana aktivnost sledećih antioksidativnih enzima: superoksid dismutaze (SOD), mangan superoksid dismutaze (MnSOD), bakar-cink superoksid dismutaze (CuZnSOD), katalaze (CAT), glutation peroksidaze (GSH-Px) i glutation reduktaze (GR). Izmerene aktivnosti antioksidativnih enzima u ispitivanim uzorcima su komparirane sa vrednostima asporbovanih doza koje su izračunate na predhodno konstruisanom voksel fantomu reprezentativnog kunića. S obzirom na činjenicu da eritrocite i tanko crevo nije moguće prikazati u voksel geometriji, stepen oksidativnih promena u ovim strukturama je poreĎen sa CTDIw vrednostima...

This study reports development of graphene reinforced nanocomposites of carboxymethyl cellulose and polyvinyl alcohol for controlled drug release applications. The nanocomposites were synthesized through solution blending coupled with sonication assisted dispersion. The matrices were crosslinked to different extent by imparting different high energy radiation doses. The elastic modulus of the polymer nanocomposites increased by fourfold with the increase in graphene content from 1 to 3 wt% with no further significant change in elastic modulus at higher graphene content. The crystalline content did not change with addition of graphene and was ∼40% for all nanocomposites. Addition of 3 wt% graphene marginally increased the time for 60% drug release (T60). However, T60 increased by ∼100% with an increase in radiation dose from 25 to 150 kGy, suggesting absorbed radiation dose to be a critical factor for graphene based nanocomposites for controlled drug release applications. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

The most frequently used and the best established method of biological dosimetry at present is the dicentric chromosome assay, which is poorly suitable for a mass casualties scenario. This gives rise to the need for the development of new, high-throughput assays for rapid identification of the subjects exposed to ionizing radiation. In the present study, we tested the usefulness of gene expression analysis in blood cells for biological dosimetry. Human peripheral blood from three healthy donors was X-irradiated with doses of 0 (control), 0.6, and 2 Gy. The mRNA level of 16 genes (ATF3, BAX, BBC3, BCL2, CDKN1A, DDB2, FDXR, GADD45A, GDF15, MDM2, PLK3, SERPINE1, SESN2, TNFRSF10B, TNFSF4, and VWCE) was assessed by reverse transcription quantitative PCR 6, 12, 24, and 48 h after exposure with ITFG1 and DPM1 used as a reference genes. The panel of radiation-responsive genes was selected comprising GADD45A, CDKN1A, BAX, BBC3, DDB2, TNFSF4, GDF15, and FDXR. Cluster analysis showed that ΔCt values of the selected genes contained sufficient information to allow discrimination between irradiated and non-irradiated blood samples. The samples were clearly grouped according to the absorbed doses of radiation and not to the time interval after irradiation or to the blood donor. Electronic supplementary material The online version of this article (doi:10.1007/s00411-015-0603-8) contains supplementary material, which is available to authorized users.

The paper reports synthesis of a new film dosimeter based on a solvent-free route. Methyl red (MR) dye was introduced into poly(chloroprene) (PC) in various concentrations. The films were intensely red with λmax ~515 nm. The absorbance decreased linearly with absorbed radiation dose up to 30 kGy without a significant change in λmax. Color coordinates of the films were also analyzed. Optical micrographs of the films showed no signs of inhomogeneous distribution of MR in the PC matrix, which was attributed to the polarity of PC. Radiation sensitivity, dose response linearity, effects of irradiation temperature and humidity, as well as the rate of fading, were also investigated.

Objectives The aim of this study was to estimate the effective absorbed radiation dose to human organs following promising in-vivo results of intravenous administration of 4-benzyl-1-(3-[125I]-iodobenzylsulfonyl)piperidine (4-B-[125I]-IBSP) using normal biodistribution data obtained from rats. Materials and methods Five rats were killed at exact time intervals and the percentage of injected dose per gram of each organ was measured by direct counting from rat data. The medical internal radiation dose formulation was applied to extrapolate from rats to humans and to project the absorbed radiation dose for various human organs. Results The dose estimation shows that the organs that received the highest absorbed dose were the brain, bone surface, and red marrow (10.51, 0.69, and 0.08 μGy/MBq, respectively). Our prediction shows that a 185 MBq injection of 4-B-[125I]-IBSP into humans might result in an estimated absorbed dose of 49.39 μGy for the whole body. The highest effective absorbed dose for 4-B-[125I]-IBSP was in the brain (19.4 μSv) and the organs that received the next highest doses were the bone surface, red marrow, muscle, and thyroid, with magnitudes of 15.27, 1.81, 0.15, and 0.10 μSv, respectively. Conclusion The results of this study suggest that 4-B-[125I]-IBSP is a suitable and safe candidate in clinical studies and in lung malignancies.

Radionuclide therapy with low-energy auger electron emitters may provide high antitumor efficacy while keeping the toxicity to normal organs low. Here we evaluated the usefulness of an auger electron emitter and compared it with that of a beta emitter for tumor treatment in in vitro models and conducted a dosimetry simulation using radioiodine-labeled metaiodobenzylguanidine (MIBG) as a model compound. We evaluated the cellular uptake of 125I-MIBG and the therapeutic effects of 125I- and 131I-MIBG in 2D and 3D PC-12 cell culture models. We used a Monte Carlo simulation code (PHITS) to calculate the absorbed radiation dose of 125I or 131I in computer simulation models for 2D and 3D cell cultures. In the dosimetry calculation for the 3D model, several distribution patterns of radionuclide were applied. A higher cumulative dose was observed in the 3D model due to the prolonged retention of MIBG compared to the 2D model. However, 125I-MIBG showed a greater therapeutic effect in the 2D model compared to the 3D model (respective EC50 values in the 2D and 3D models: 86.9 and 303.9 MBq/cell), whereas 131I-MIBG showed the opposite result (respective EC50 values in the 2D and 3D models: 49.4 and 30.2 MBq/cell). The therapeutic effect of 125I-MIBG was lower than that of 131I-MIBG in both models, but the radionuclide-derived difference was smaller in the 2D model. The dosimetry simulation with PHITS revealed the influence of the radiation quality, the crossfire effect, radionuclide distribution, and tumor shape on the absorbed dose. Application of the heterogeneous distribution series dramatically changed the radiation dose distribution of 125I-MIBG, and mitigated the difference between the estimated and measured therapeutic effects of 125I-MIBG. The therapeutic effect of 125I-MIBG was comparable to that of 131I-MIBG in the 2D model, but the efficacy was inferior to that of 131I-MIBG in the 3D model, since the crossfire effect is negligible and the homogeneous distribution of radionuclides was insufficient. Thus, auger electrons would be suitable for treating small-sized tumors. The design of radiopharmaceuticals with auger electron emitters requires particularly careful consideration of achieving a homogeneous distribution of the compound in the tumor.

Measurements of ambient gamma radiation dose and radioactivity of soil and rocks samples have been carried out in 103 sites located in the region of Marrah mountain (western Sudan) using survey meters and gamma spectrometry techniques, respectively. The ambient dose varied from 0.05 to 0.25 µSv/h with mean value of 0.18 ± 0.05 (SD) µSv/h. At high altitudes (> 1500 m), relatively high values were observed (0.18–0.22 µSv/h). The levels of 238U, 232Th and 40K in soil–rocks were in the ranges 12–80, 12–66 and 120–937 Bq/kg with mean ± SD of (41 ± 6.9), (24 ± 12) and (540 ± 99) Bq/kg, respectively, equivalent to total gamma absorbed dose of 23–142 (66 ± 20) nGy/h. The ambient dose data were presented in cartography format, and correlation to geological maps was attempted. Surface map of the absorbed dose created using geostatistical kriging tools showed the spatial distribution of dose. Analyses showed that trends of high values were located in and around areas characterized by local flow and basaltic flow lithology, while the low values were observed at locations of basement rocks (granitic) in general. That was attributed to the differences in environmental conditions in various altitude and weathering processes. The highest readings (0.25 µSv/h and 142 nGy/h) were found in Deriba Complex Pumice air-fall deposits (younger explosive phase). Health risk was assessed by calculating annual effective dose for the inhabitants resulted in values range between 0.14 and 1.4 mSv/y (mean ± SD of 0.40 ± 0.12 mSv/y). The observed values of dose rates are comparable with some countries but higher than the worldwide average for outdoor annual affective dose of 0.07 mSv/y.

The possibility of developing radiation detectors based on field-effect transistors (FET) is investigated. Transistor saturation current is chosen as an informative parameter for modeling. Experimental results show that the drain saturation current of the FET with p-n junction as a gate is decreasing after irradiation. In metal-oxide-semiconductor (MOS) FETs during radiation-induced defect formation two effects are competing, therefore the result of radiation influence is highly dependent on the electro-physical properties of transistors before irradiation and on the absorbed radiation dose. It is shown that saturation current increases with absorbed radiation dose for all the transistors with low electron concentration in a channel above certain levels of absorbed radiation. While the opposite effect is observed for high electron concentration in a channel, i.e. the saturation current drops. Obtained dependences of the drain saturation current of FET on the irradiation dose facilitated development of simple detector design for low levels of radiation. The bridge circuit is used in the radiation sensor to minimize the effect of temperature fluctuations. The sensitivity of the detector is enhanced several times with the help of two pairs of FETs with the opposite sign of radiation sensitivity.

Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

In this study, Electron Paramagnetic Resonance (EPR) spectra of unirradiated and γ-irradiated at doses of 1, 5, 10, 12 and 15 kGy norfloxacin (NOF) were investigated. Before irradiation no EPR signal were observed. After irradiation a weak singlet signal at g = 2.0039 were obtained at room temperature. In order to describe the variation of EPR signal intensity with absorbed radiation dose, several mathematical equations were tried. Increasing irradiation dose up to 15 kGy has increased the signal intensity of the central signal however, no significant changes were observed in g spectroscopic splitting factor. The stability of signal intensity of irradiated NOF was studied over a storage period of 200 days. According to analyses conducted, EPR spectroscopy can be used to distinguish irradiated and unirradiated samples from each other.

The effect of three different acrylate group monomers, namely n-butyl acrylate, methacrylic acid and tripropylene glycol diacrylate of radiation induced grafting onto waste rubber was studied. The electron beam accelerator operated at voltage of 2MeV was used to irradiate the waste rubber at 10 kGy and 100 kGy absorbed radiation dose, respectively. The formation of grafting was observed from the increase in the grafting yield and confirmed by Transformed Infra-Red Spectroscopy results. According to the result obtained, only tripropylene glycol diacrylate was selected to graft onto waste rubber. The carbonyl bond from acrylate groups was seen at 1726 cm -1 band which confirmed the presence of TPGDA in the polymer matrix. This indicates the successful preparation of the TPGDA-grafted waste rubber via radiation induced grafting techniques.

By means of a recently-proposed metric or structural derivative, called scale-q-derivative approach, we formulate differential equation that models the cell death by a radiation exposure in tumor treatments. The considered independent variable here is the absorbed radiation dose D instead of usual time. The survival factor, Fs, for radiation damaged cell obtained here is in agreement with the literature on the maximum entropy principle, as it was recently shown and also exhibits an excellent agreement with the experimental data. Moreover, the well-known linear and quadratic models are obtained. With this approach, we give a step forward and suggest other expressions for survival factors that are dependent on the complex tumor structure., Comment: 6 pages, 2 collumns

This study develops and compares different, increasingly detailed anatomical phantoms for rainbow trout (Oncorhynchus mykiss) for the purpose of estimating organ absorbed radiation dose and dose rates from (131)I uptake in multiple organs. The models considered are: a simplistic geometry considering a single organ, a more specific geometry employing additional organs with anatomically relevant size and location, and voxel reconstruction of internal anatomy obtained from CT imaging (referred to as CSUTROUT). Dose Conversion Factors (DCFs) for whole body as well as selected organs of O. mykiss were computed using Monte Carlo modeling, and combined with estimated activity concentrations, to approximate dose rates and ultimately determine cumulative radiation dose (μGy) to selected organs after several half-lives of (131)I. The different computational models provided similar results, especially for source organs (less than 30% difference between estimated doses), and whole body DCFs for each model (∼3 × 10(-3) μGy d(-1) per Bq kg(-1)) were comparable to DCFs listed in ICRP 108 for (131)I. The main benefit provided by the computational models developed here is the ability to accurately determine organ dose. A conservative mass-ratio approach may provide reasonable results for sufficiently large organs, but is only applicable to individual source organs. Although CSUTROUT is the more anatomically realistic phantom, it required much more resource dedication to develop and is less flexible than the stylized phantom for similar results. There may be instances where a detailed phantom such as CSUTROUT is appropriate, but generally the stylized phantom appears to be the best choice for an ideal balance between accuracy and resource requirements.

Purpose To characterize the distribution of absorbed radiation dose after glass microsphere radioembolization for hepatocellular carcinoma (HCC) using yttrium-90 ( 90 Y) positron emission tomography/computed tomography (PET/CT). Materials and Methods In this retrospective study, 64 90 Y PET/CT scans performed after treatment were evaluated following 90 Y glass-bead radioembolization in patients with advanced HCC. The intended dose to the target volume ranged from 83–129 Gy. Three-dimensional "dose maps" were created from reconstructed PET images using a voxel-based S-value transformation. Liver parenchyma and liver tumors were contoured on cross-sectional imaging and aligned with the created dose maps. Results There were 113 tumors examined as part of 64 lobar treatments. The average tumor size was 4.8 cm ± 4.0 with an average tumor dose of 173 Gy ± 109. The average dose to the nontumor parenchyma within the target volume was 93.4 Gy ± 32.6, with on average 50% of the parenchymal voxels receiving > 79 Gy ± 23 and 10% receiving > 173 Gy ± 55. The average and median tumor-to-parenchymal weighted dose ratios were 2.2 and 1.9, respectively. Conclusions Using recommended dosimetry and administration techniques for lobar glass microsphere radioembolization, high doses to target tumors as well as background parenchyma were achieved on average with modest preferential uptake within tumors. There was wide variation in measured tumor and parenchymal doses after hepatic radioembolization for HCC, suggesting the need for continued development of patient-specific dosimetry.

There is a concern regarding the adverse effects of increasing radiation doses due to repeated computed tomography (CT) scans, especially in radiosensitive organs and portions thereof, such as the lenses of the eyes. Bismuth shielding with an adaptive statistical iterative reconstruction (ASIR) algorithm was recently introduced in our clinic as a method to reduce the absorbed radiation dose. This technique was applied to the lens of the eye during CT scans. The purpose of this study was to evaluate the reduction in the absorbed radiation dose and to determine the noise level when using bismuth shielding and the ASIR algorithm with the GE DC 750 HD 64-channel CT scanner for CT of the head of a humanoid phantom. With the use of bismuth shielding, the noise level was higher in the beam-hardening artifact areas than in the revealed artifact areas. However, with the use of ASIR, the noise level was lower than that with the use of bismuth alone; it was also lower in the artifact areas. The reduction in the radiation dose with the use of bismuth was greatest at the surface of the phantom to a limited depth. In conclusion, it is possible to reduce the radiation level and slightly decrease the bismuth-induced noise level by using a combination of ASIR as an algorithm process and bismuth as an in-plane hardware-type shielding method.

In this paper, the results of radiation sensitive field effect transistors (Al-gate p-channel metal-oxide-semiconductor field effect transistors) sensitivity to gamma and X-ray irradiation are presented. Radiation fields were created using 60Co source for three dose ranges (0-1 Gy, 0-5 Gy, and 0-50 Gy), as well as X-ray unit of 280 kVp spectrum for a single dose range from 0 to 5 Gy. The sensitivity was characterized by the threshold voltage shift, determined from reader circuit measurements, as a function of absorbed radiation dose. It was shown that for the three dose ranges of gamma radiation, as well as for the X-ray range from 0 Gy to 5 Gy there is approximately a linear dependence between threshold voltage shift DVT and radiation dose D. The application of positive bias of +5 V at the RADFET gate during irradiation, for these ranges of gamma radiation, also for X-ray dose range, leads to the increase in DVT and also, approximately a linear dependence between DVT and D, is established. Moreover, it was shown that the sensitivity of RADFET is much higher in the case of X-ray irradiation then in the case of gamma-ray irradiation for the same dose range. [Projekat Ministarstva nauke Republike Srbije, br. 171007]

Quantification of radiation dose to normal tissue during radiotherapy is critical for assessing risk for radiotherapy-related late effects, including subsequent neoplasms (SNs). Case-control studies of SNs typically reconstruct absorbed radiation dose to the specific SN location using individual treatment parameters. A simplified method estimates the maximum prescribed target dose to the body region in which the SN arises. We compared doses and risk estimates from these methods using data from case-control studies of subsequent brain tumors (64 cases, 244 controls) and breast cancer (94 cases, 358 controls) nested within the Childhood Cancer Survivor Study (≥5-year survivors of childhood cancer diagnosed 1970–1986). The weighted kappa statistic [95% confidence interval (CI)] evaluating agreement between categorical (>0–9.9/10–19.9/20–29.9/≥30 Gy) body-region and tumor location-specific doses was 0.95 (0.91–0.98) for brain and 0.76 (0.69–0.82) for breast. The body-region and location-specific doses were assigned to the same dose category for a smaller proportion of patients treated with fields delivering a heterogeneous dose across the tissue of interest (e.g., partial brain field = 57.1%; mantle field = 61.3%) than patients treated with fields delivering a more homogeneous dose (e.g., whole brain field = 100%). Excess odds ratios per Gy (95% CI) from conditional logistic regression were 1.25 (0.33–6.33) and 1.20 (0.31–6.14) for brain tumors and 0.21 (0.05–0.77) and 0.10 (0.02–0.44) for breast cancer, using location-specific and body-region doses, respectively. We observed that body-region doses can approximate location-specific doses when the tissue of interest is clearly in the radiation field or outside the treated body region. Agreement is lower when there is greater ambiguity of SN location relative to the treatment field.

Un-irradiated potassium citrate exhibited a weak ESR singlet at g = 2.0045 ± 0.0003 with peak-to-peak line-width of ΔHpp = 0.16 mT. However, multi-resonance signals spreading over a magnetic field range of ~5 mT were observed in gamma irradiated potassium citrate. A linear function of absorbed radiation dose was found to describe well the dose-response curves of the resonance signals A, B and C in a dose range of 5–5000 Gy. Room temperature fading study showed that radiation-induced radicals in potassium citrate are highly stable but less stable when exposed to the sunlight. Three different radical species were found to describe well experimental room temperature ESR spectrum of irradiated potassium citrate. The resonance signal B can be used in measuring the accidental radiation doses and the radiation doses used in food industry, at least up to a dose of 5 kGy. Further studies were needed in order to increase the sensitivity of potassium citrate at low radiation doses.