REVIEW | doi:10.20944/preprints202312.0546.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: radiation, C-vitamin; solar particle event; SPE; antioxidants; radiation mitigator
Online: 7 December 2023 (19:55:54 CET)
Space exploration introduces astronauts to many challenges such as space radiation and microgravity. Researchers have investigated vitamin C as a potential radiation mitigator and antioxidants for sustaining astronaut health. Building on our own studies, which indicate vitamin C's life-saving radioprotective effects and its potential as a radiation mitigator, our research highlights its promise, even when administered 24 h post-exposure. This is particularly relevant in scenarios where astronauts may be exposed to sudden large solar particle events, potentially resulting in lethal doses of space radiation. The success of vegetable cultivation on the International Space Station using NASA's Veggie system offers fresh, vitamin C-rich food. While approved supplements address somatic function, further research is needed to optimize vitamin C's efficacy in humans and develop antioxidant cocktails for space missions. The variable vitamin C content in vegetables underscores the necessity for utilization of artificial intelligence (AI) to assist astronauts in selecting and cultivating vitamin C-rich vegetables that are best suited to combat high levels of space radiation and microgravity. Particularly, AI algorithms can be utilized in analyzing various factors such as nutritional content, growth patterns, and cultivation methods. In conclusion, vitamin C shows significant potential for mitigating space radiation, and ongoing research aims to enhance astronaut health through optimal dietary strategies.
ARTICLE | doi:10.20944/preprints202311.1861.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: THz radiation; femtosecond laser-induced breakdown; air breakdown; spatiotemporal control; coupling of temperature; density gradients in plasma; tunnelling ionisation
Online: 29 November 2023 (10:53:19 CET)
Two pre-pulses focused at different positions and at different time moments were used to enhance THz emission generated by the main pulse. The emission of THz radiation from air breakdown regions of focused ultrashort fs-laser pulses (800 nm/35 fs) at shockwave front prepared by pre-pulses was investigated, and a 3D spatio-temporal control was established for the most intense emission. The laser pulse-induced air breakdown forms a ~120 micrometers-long focal volume and generates a shockwave that delivers denser air into the focal region of the main pulse for enhanced generation of THz radiation at 0.1-2.5 THz spectral window. The intensity of pre- and main-pulses was at the tunneling ionisation intensities (1-3)x1016 W/cm2 and corresponded to sub-critical (transparent) plasma in air. Polarisation analysis revealed that the orientation of the air density gradients generated by pre-pulses and their time-space placement defined the ellipticity of the generated THz electrical field. The rotational electric current is the origin of THz radiation. The current is created by non-parallel gradients of electron density and temperature. Scaling dependencies of THz emission control are established.
ARTICLE | doi:10.20944/preprints202311.1566.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Diamond; NV centers; scattering; X-ray diffraction analysis; orientation of NV centers
Online: 24 November 2023 (10:38:00 CET)
It is well known that the basis of diffraction analysis of matter is scattering, including scattering of ultrashort laser pulses. In the theory of scattering of ultrashort pulses the pulse duration parameter is usually not taken into account, which leads to some error. This error may be more significant than the considered effects in the scattering of the pulse on the studied structure. In this paper it is shown that the pulse duration parameter should be taken into account when scattering X-ray pulses on oriented diamonds with NV-centers. It is shown that the scattering spectra can be used to judge the orientation of NV centers in the diamond structure. The obtained results may be very different from the widely used theory of diffraction analysis, which confirms the necessity of taking into account the pulse duration parameter in the diagnosis of complex structures.
REVIEW | doi:10.20944/preprints202311.1275.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Radiation; nuclear DNA; radiobiology; mitochondrion; GCR; DNA damage and re-pair mechanisms; mitochondrial DNA; organelles; HZE
Online: 21 November 2023 (07:24:39 CET)
Astronauts in space are subject to a continuous bombardment of ionizing radiation. The Earth's magnetic field and the ISS shield some biologically damaging particles traveling through. Still, travel beyond low-Earth orbit and extravehicular activities are exceedingly more dangerous and there is a concern for the acute and late-occurring adverse health effects befalling astronauts. So, it is vital to consider the current tools and models used to describe and study the organic consequences of ionizing radiation exposure. It is equally important to see where these models may improve. This article reviews the historical development and current state of knowledge of radiation effects impacting astronauts in orbit. We explain the space radiation environment, cellular microenvironment, and how these may be incorporated in radiobiological models to aid in our understanding of the influence space travel may have on astronaut health. The topics discussed in this paper include a review of DNA damage and repair mechanisms and the numerical models that aim to explain the biological effects resulting from ionizing radiation damage. Historically, radiobiological models focused on how radiation damages nuclear DNA, built upon the hypotheses of Crowther and Lea in the 1940s and 1960s, and neglected other sub-cellular targets outside of nuclear DNA.
ARTICLE | doi:10.20944/preprints202310.1381.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: patient dose; CT guided biopsy procedures; Diagnostic Reference Levels
Online: 21 October 2023 (17:40:38 CEST)
ABSTRACT Objectives: Typical Diagnostic Reference Levels (DRL) in terms of Computed Tomography Dose Index (CTDI) and patient dose in terms of Effective Dose (ED ) and Size Specific Dose Estimate (SSDE) were estimated in Computed Tomography (CT) guided biopsy procedures. Materials and Methods: A total of 226 CT biopsy procedures - Iliac bone, liver, lung, mediastinum and para-aortic tissue - were retrospectively analyzed and Typical DRL extracted based on ICRP 135 instructions. Results: For helical mode acquisitions, DRLs in terms of CTDIvol were 9.7 mGy for Iliac bone, 8.9 mGy for liver, 8.8 mGy for lung, 7.9 mGy for mediastinal mass and 9 mGy for para-aortic lymph nodes biopsy procedures. For biopsy acquisitions, DRL values were 7.3 mGy, 7.7 mGy, 5.6 mGy, 5.6 mGy and 7.4 mGy respectively. Also, SSDE median values ranged from 7.6 mGy to 10 mGy for biopsy acquisitions and 11,3 mGy to 12,6 mGy for helical acquisitions, as well as the median values for effective dose ranged from 1.6 mSv to 5,7 mSv for biopsy scans and 3.9 to 9.3 mSv for helical scans. Conclusions: The use of DLR as an optimization tool for CT-guided biopsy procedures revealed that helical scans across the entire anatomical region greatly affect radiation dose compared to biopsy acquisitions.
ARTICLE | doi:10.20944/preprints202310.0518.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Compton camera; wide-energy range; Monte Carlo simulation; scintillation detector; image reconstruction
Online: 9 October 2023 (11:08:24 CEST)
(1) Background: The imaging energy range of a typical Compton camera is limited due to the fact that scattered gamma photons are seldom fully absorbed when the incident energies are above 3 MeV. Further improving the upper energy limit of gamma-ray imaging has important application significance in active interrogation of special nuclear materials and chemical warfare agents, as well as range verification of proton therapy; (2) Methods: To realize gamma-ray imag-ing in a wide energy range of 0.3~7 MeV, a principle prototype, named a portable three-layer Compton camera, was developed using the scintillation detector that consist of an silicon photo-multiplier array coupled with a Gd3Al2Ga3O12:Ce pixelated scintillator array. Implemented in a list-mode maximum likelihood expectation maximization algorithm, a far-field energy-domain imaging method based on two-interaction and three-interaction events was applied to estimate the initial energy and spatial distribution of gamma-ray sources. The simulation model of detec-tors was established based on Monte Carlo simulation toolkit Geant4. The reconstructed images of a 133Ba, a 137Cs and a 60Co point-like sources were successfully obtained with our prototype in laboratory tests and compared with simulation studies; (3) Results: The proportion of effective imaging events accounted for about 2%, which made our prototype realize reconstructing the distribution of a 0.05 μSv/h 137Cs source in 10 seconds. The angular resolution for resolving two 137Cs point-like sources was 15°. Additional simulated imaging of the 6.13 MeV gamma-rays from 14.1 MeV neutron scattering with water preliminarily demonstrated the imaging capability for high incident energy; (4) Conclusions: We concluded that the prototype had good imaging per-formance in a wide energy range (0.3~7 MeV), which showed potential in several MeV gam-ma-ray imaging applications.
TECHNICAL NOTE | doi:10.20944/preprints202309.1575.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: semiconductor survey meter; calibration; medical X-ray system; calibration factor; time constant
Online: 25 September 2023 (11:44:59 CEST)
In recent years, semiconductor survey meters have been developed and are in increasing demand worldwide. This study aimed to investigate whether it is possible to calculate the time constant of the semiconductor survey meter using the X-ray equipment installed in each medical facility and whether it is possible to calibrate the semiconductor survey meter. Attach an additional filter to the medical X-ray system to satisfy the standards of N-60 to N-120, add more copper plates from there, and calculate the first and second half-value layers to compare with N-60 to N-120 values. Next, we will measure the leakage dose using a medical X-ray system and calculate the time constant of the survey meter. The survey meter is then calibrated and compared with the calibration factors in industrial X-ray system. Per experimental results, it is possible to reproduce the N-60 to N-120 radiation quality using a medical X-ray system and to calculate the time constant from the measured results assuming actual leakage dosimetry using that radiation quality. We also found that the calibration factor was equivalent to that of an industrial X-ray device. It was revealed that semiconductor survey meters can be calibrated using a medical X-ray system.
ARTICLE | doi:10.20944/preprints202309.1559.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: 3D printed anthropomorphic models; Educational phantoms; Higher education; Radiologic technologists; breast models
Online: 22 September 2023 (13:06:46 CEST)
The aim of this study is to introduce and evaluate a new approach by using 3D printed anthropomorphic breast phantoms in teaching X-ray mammography techniques Radiologic technologists. For this purpose, a physical anthropomorphic breast phantom is created, based on a computational breast version. The phantom is created by a stereolithography 3D printer. The practical exercises were conducted in three sessions with the participation of radiographers students first, second and third year of training, respectively. A survey was prepared to summarise the participants´ opinion about this new form of training in mammography technique. A total of 83 students were trained with the new approach. From these 52 responded to the survey questions. More than half of the students (71.2%) successfully handled the exercise with the physical breast phantom. The training provoked a substantial number of students to express the belief that incorporating modern methods based on digital technologies into their X-ray device training is essential. The instructor was well prepared and with the needed competence. The experience within this training convinces the future professionals to introduce the new technologies in their routine work, particularly for exercising the compression technique and breast positioning.
REVIEW | doi:10.20944/preprints202308.0657.v2
Subject: Physical Sciences, Radiation And Radiography Keywords: image quality; interventional radiology; pediatrics
Online: 30 August 2023 (04:05:02 CEST)
Pediatric interventional cardiology procedures are essential in diagnosing and treating congenital heart disease in children; however, they raise concerns about potential radiation exposure. Managing radiation doses and assessing image quality in angiographs becomes imperative for safe and effective interventions. This systematic review aims to comprehensively analyze the current understanding of physical image quality metrics relevant for characterizing X-ray systems used in fluoroscopy-guided pediatric cardiac interventional procedures, considering the main factors reported in the literature that influence this outcome. A search in Scopus and Web of Science, using relevant keywords and inclusion/exclusion criteria, yielded fourteen relevant articles published between 2000 and 2022. The physical image quality metrics reported were noise, signal-to-noise ratio, contrast, contrast-to-noise ratio, and high contrast spatial resolution. Various factors influencing image quality were investigated, such as polymethyl methacrylate thickness (often used to simulate water equivalent tissue thickness), operation mode, anti-scatter grid presence and tube voltage. Objective evaluations using these metrics ensure impartial assessments for main factors affecting image quality, improving in the characterization fluoroscopic X-ray systems, and aiding informed decisions to safeguard pediatric patients during procedures.
REVIEW | doi:10.20944/preprints202308.1323.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: hipoxya; carbon ions; LET; particle therapy
Online: 18 August 2023 (09:58:14 CEST)
Hypoxia, associated with abnormal vessel growth, is a characteristic feature of many solid tumors that increases their metastatic potential and resistance to radiotherapy. Carbon ion radiation therapy, alone or in combination with other treatments, is one of the most promising treatments for hypoxic tumors because the oxygen enhancement ratio decreases with increasing particle LET. Nevertheless, the current clinical practice does not yet fully benefit from using carbon ions for tackling hypoxia. Here we give an overview of the existing experimental and clinical evidence supporting the efficacy of C-ion radiotherapy in overcoming hypoxia-induced radioresistance, followed by a discussion of the strategies proposed to enhance it, including different approaches to maximize the LET in the tumors.
ARTICLE | doi:10.20944/preprints202307.1732.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Ultra wide band radar; Artificial Intelligence; 3D radar; MIMO radar; counter-terrorism
Online: 26 July 2023 (08:45:47 CEST)
DEXTER (Detection of EXplosives and firearms to counter TERrorism) is a project funded by NATO’s Science for Peace and Security (SPS) program with the goal of developing an integrated system capable of remotely and accurately detecting explosives and firearms in public places without impeding the flow of pedestrians. The active microwave component of the DEXTER project is referred to as MIC (Microwave Imaging Curtain), supported by the French SGDSN (General Secretariat of Defense and National Security), and utilizes a radar system capable of generating 3D images in real time to address non-checkpoint detection of explosives and fire-arms. The project, led by the ONERA (France), is based on a radar imaging system developed by the Fraunhofer FHR institute, using a MIMO architecture with an Ultra Wide-Band waveform. Although high-resolution 3D microwave imaging is already being used in expensive body scanners to detect firearms concealed under clothing, MIC's innovative approach lies in utilizing a high-resolution 3D imaging device that can detect larger dangerous objects carried by moving individuals at a longer range, in addition to providing discrete detection in pedestrian flow. Automatic detection and classification of these dangerous objects is carried out on 3D radar im-ages using a deep-learning network. This paper will outline the project's objectives and constraints, as well as the design, architecture, and performance of the final system. Additionally, it will present real-time imaging results ob-tained during a live demonstration in a relevant environment.
ARTICLE | doi:10.20944/preprints202307.1490.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Ir-192; HDR brachytherapy; dosimetry; Monte Carlo; EGS5
Online: 21 July 2023 (09:24:49 CEST)
After 2010, the source model of the microSelectron HDR Afterloader System was slightly modified from the previous model. Granero et al. named the modified source model “mHDR-v2r (revised model mHDR-v2)” and the previous model “mHDR-v2”. They concluded that the dosimetric diﬀerences arising from the dimensional changes between the mHDR-v2 and mHDR-v2r designs were negligible at almost all locations (within 0.5 % for r ≥ 0.25 cm), the two-dimensional anisotropy function diﬀerence between the two sources is found 2.1 % at r = 1.0 cm when compared with the results of the other experimental group. To confirm this diﬀerence, we performed a full Monte Carlo simulation without the energy fluence approximation. This is useful near the radiation source where charged-particle equilibrium does not hold. The two-dimensional anisotropy function of the TG-43U1 dataset showed a few percent difference between the mHDR-v2r and mHDR-v2 sources. There was no agreement in the immediate vicinity from the source (0.10 cm and 0.25 cm), when compared to Granero et al. in mHDR-v2r sources. The differences in these two-dimensional anisotropy functions were identified.
ARTICLE | doi:10.20944/preprints202307.0242.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Homogeneous phantom; heterogeneous phantom; radiation dosimetry
Online: 5 July 2023 (02:45:28 CEST)
Introduction: To compare the results of patient-specific absolute dosimetry using homogeneous slab phantom and anthropomorphic heterogeneous female pelvic phantom in cervical cancer patients. Materials and method: Thirty RapidArc plans already planned on treatment planning system (TPS) for cervical cancer patients were exported on both the phantoms viz. RW3 slab phantom and AHFP and dose were calculated using an anisotropic analytic algorithm (AAA). All the plans were delivered by linear accelerator (LA) and the dose for each plan was measured by a 0.6cc ion chamber. The percentage (%) variation between planned and measured doses were calculated and analyzed.Results: In the case of slab phantom, the mean percentage variations between planned and measured doses of all rapid arc QA plans were as 1.4299 and standard deviation 0.768 (t=0.00508, ρ= 0.497982) The result is not significant at p < .05. For the AHFP phantom, the mean percentage variations between planned and measured doses of all rapid arc QA plans were as 6.890 and standard deviation 2.565 (t= 3.21604, ρ= 0.001063 <0.05), the outcome is significant. Discussion: In the case of homogenous slab phantom, there is less than a 3% difference in percentage between planned and measured doses with a standard deviation of 0.7682 (t=0.00508, p= .497982. The result is not significant at p< 0.05). The deviations of planned and measured value of dose in the AHFP phantom were found as 10.67% (maximum value), 2.31% (minimum value) and 6.89% (average value) with standard deviation 2.565 (t=3.21604, p=0.001063. The result is significant at p<0.05). Also, the percentage of variation between homogeneous slab phantoms with AHFP phantom, the t-value is -11.17016. The p-value is < .00001. The result is significant at p<0.05. We can see that the outcomes differ significantly due to the influence of heterogeneous media.Conclusion: AHFP phantom results showed more dose variability than slab homogenous phantom outcomes. Therefore, patient-specific absolute dosimetry should be performed using a heterogeneous phantom that closely resembles the actual human body in terms of both density and design.
ARTICLE | doi:10.20944/preprints202306.1370.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: adolescent idiopathic scoliosis; pose estimation; posture parameters; mobile devices; deep learning; clinical photography; mobile applications; MoveNet, convolutional neural network; kinematics; posture; reliability; validity
Online: 19 June 2023 (14:27:12 CEST)
Background. Pose estimation based on deep learning has been expected to be a breakthrough method to increase the accuracy of clinical photographic evaluation and to decrease interobserver errors. The purpose is to quantify pose estimation from photography of patients with adolescent idiopathic scoliosis (AIS) using open-source software packages and determine correlations between parameters obtained by radiography and photography. Methods. We included 12 consecutive patients with AIS treated with spinal correction surgery. Photographs were taken preoperatively using a tripod-mounted camera (iPhone 13Pro) on an X-ray tube head. To assess photographic parameters obtained by photography, we defined 17 points to analyze posture and define parameters. Results. In the sagittal plane, there was a significant correlation between the radiographic trunk tilt angle and the photographic sagittal trunk tilt angle of the shoulder–hip and ear–hip. In the coronal plane, there was a significant correlation between the radiographic clavicle angle and the photographic shoulder height angle, and the radiographic C7–CSVL and the photographic coronal trunk tilt angle. Conclusions. Posture analysis by photography using popular mobile devices has clinical utility for improving and promoting the screening and early detection of AIS because it is simple, without patient exposure to X-ray radiation.
ARTICLE | doi:10.20944/preprints202304.0525.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: MOS semiconductor; Zinc Oxide; Radiation Simulation; Finite Element Analysis; Radiation damage; Space application
Online: 19 April 2023 (02:38:32 CEST)
In this paper, we present the investigation results of radiation-induced effects in metal-oxide-semiconductor (MOS) doped with moderate amounts of Zinc Oxide (ZnO) as a potential candidate for space-borne application. The samples were fabricated via the sputtering method at a working pressure of 3mTorr and a deposition temperature of 300oC. The ZnO samples were exposed to 1.25-MeV gamma-ray utilizing Co60 source, and their electronic response was measured at ionizing doses ranging from 10 kGy to 300 kGy. A comparative work was performed through finite element method to simulate the electronic response of the PN junction diode due to ionizing radiation. The results indicate that the ideality factor of the MOS diode increases as the ionizing dose increases, rendering it unsuitable for use as a diode. The degradation of the electrical parameters was also simulated, showing the increase in hole concentration. These findings suggest that the ejection of electrons occurred, which agrees with the gamma radiation effects trend. Furthermore, as the intensity of radiation increases, the spatial charge that arises from the separation of hole-electron pairs results in a substantial reduction of the electric field in the central portion of the n-type region. These findings provide insights into the degradation of electrical parameters in MOS devices under gamma radiation and have implications for their use in space-borne applications.
CONCEPT PAPER | doi:10.20944/preprints202301.0444.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: radioactive waste; radioactive waste processing; radioactive waste disposal; trinitite; radioactive gemstones; radioactive corundum; radioactive sapphire; radioactive ruby
Online: 25 January 2023 (04:14:53 CET)
The possibility of making precious stones from radioactive waste is being considered. Vitrified and cemented radioactive waste (RW) is considered as an artificial rock belonging to aluminosilicates and calcites. Two methods are proposed for the manufacture of radioactive gemstones from RW and their subsequent storage with the possibility of sale, resale, inheritance, and so on. That is, RW is considered as real estate in which capital can be invested. After decontamination in hundreds and thousands of years, it will be of scientific, historical, jewelry interest.
ARTICLE | doi:10.20944/preprints202212.0248.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Detector Response Unfolding; Neutron Spectrum Unfolding; Machine Learning; Neural Network; Feature Engineering
Online: 14 December 2022 (06:43:36 CET)
Neural networks require a large quantity of training spectra and detector responses in order to learn to solve the inverse problem of neutron spectrum unfolding. In addition, due to the under-determined nature of unfolding, non-physical spectra which would not be encountered in usage should not be included in the training set. While physically realistic training spectra are commonly determined experimentally or generated through Monte Carlo simulation, this can become prohibitively expensive when considering the quantity of spectra needed to effectively train an unfolding network. In this paper, we present three algorithms for the generation of large quantities of realistic and physically motivated neutron energy spectra. Using an IAEA compendium of 251 spectra, we compare the unfolding performance of neural networks trained on spectra from these algorithms, when unfolding real-world spectra, to two baselines. We also investigate general methods for evaluating the performance of and optimizing feature engineering algorithms.
ARTICLE | doi:10.20944/preprints202209.0468.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Diamond; NV centre; ultrashort pulse; scattering; scattering spectra; X-ray diffraction analysis
Online: 29 September 2022 (11:04:56 CEST)
Scattering of ultrashort X-ray pulses (USP) is an important component of the diffraction analysis of matter using modern USP sources. Usually, the specific scattering of such USPs is not taken into account to determine the structure of a substance. Taking into account the specifics of scattering on complex structures will give more accurate results when deciphering complex structures. In this work, it is shown that when X-ray USPs are scattered on diamond with NV centers, it is necessary to take into account the pulse duration. The results obtained can be very different from the widely used theory of diffraction analysis, which confirms the need to take into account the specifics of USP scattering when diagnosing complex structures. It is also shown that scattering spectra are quite sensitive to the concentration of NV centres in the diamond structure and this can be used in diffraction analysis.
ARTICLE | doi:10.20944/preprints202207.0188.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: recycling; radioactive waste; radioactive nanopowders; radioactive nanocomposites; radioactive semiconductor devices; radioactive space microelectronics; space industry
Online: 12 July 2022 (10:08:57 CEST)
The article provides an overview of nanocomposites and microelectronic elements used in space electronics and radiation control systems of nuclear reactors. Only those nanocomposites and microelectronic elements are taken into account that improve their characteristics in radiation fields or remain indifferent when exposed to ionizing radiation. Considering the chemical composition of the materials of these nanocomposites and microelectronic elements, it is analyzed from which radioactive materials (RM) obtained by recycling radioactive waste (RW) such composites and microelectronic parts can be made. Thus, an alternative way of radioactive waste disposal is proposed, when these wastes are used in the form of microelectronic elements designed to operate under conditions of cosmic radiation.
ARTICLE | doi:10.20944/preprints202205.0198.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: radioactive waste; radioactive waste recycling; industrial slag; industrial ash; aerospace industry
Online: 16 May 2022 (07:50:42 CEST)
The article discusses an alternative way of recycling radioactive waste (RW), presented in the form of radioactive building materials - concrete and reinforced concrete structures and metal fittings, with the further use of materials, obtained during recycling, in the space industry. That is, it is supposed to send radioactive waste into space not as a passive ballast, but as a payload that will operate in space under conditions of increased radiation.
ARTICLE | doi:10.20944/preprints202203.0044.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: energetic material; plasma; detonation; electromagnetism; high temperature
Online: 2 March 2022 (10:39:48 CET)
In the process of deflagration of energetic materials, strong electromagnetic radiation is to be generated, which causes the surrounding electronic equipment to fail to work normally. To solve this problem, it is necessary to clarify the mechanism of electromagnetic radiation generated by energetic materials. The mechanism of plasma changed by the deflagration of energetic materials is an important topic in the aerospace and geophysics fields. The academic community holds two main viewpoints on the mechanism of electromagnetic radiation generated by energetic materials: one is that the solid material is squeezed and deformed during the deflagration of energetic materials, and the charges of different polarities rub in space to form effective electric dipoles, which eventually generate electromagnetic radiation. Another view is that the deflagration of energetic materials causes the temperature of the medium to rise sharply, and bremsstrahlung is formed during the compression and diffusion of the high-temperature wave front, resulting in the generation of electromagnetic radiation. This paper, based on theoretical analysis and experimental data, holds the view that electromagnetic radiation is generated by the high-temperature thermal effect. It studies the relationship between temperature and electromagnetic radiation and obtains quantitative analysis conclusions.
ARTICLE | doi:10.20944/preprints202203.0043.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: explosion; energetic material; electromagnetic radiation; characteristic
Online: 2 March 2022 (10:37:39 CET)
During the explosion of energetic materials, obvious electromagnetic interference will be generated, which will affect the normal operation of surrounding electronic equipment. Experiments are still an important means to study this issue. A set of electromagnetic radiation measurement device based on short-wave omnidirectional antenna and ultra-wideband omnidirectional antenna is designed to measure the electromagnetic radiation generated by the explosion of energetic materials of different masses, and the electromagnetic radiation characteristics are obtained through data processing. The results show that the mass of the energetic material has a significant effect on the time-domain characteristics of the electromagnetic radiation generated by the explosion: the higher the mass of the energetic material, the shorter the delay response of the electromagnetic signal, the longer the duration, and the earlier the peak appears. The frequency of electromagnetic radiation signals generated by the explosion of energetic materials is mainly concentrated below 100 MHz, and the energy is most concentrated in the frequency band of 0~50 MHz. The composition of energetic materials has the greatest influence on the spectral distribution, and the spectral distribution of electromagnetic radiation produced by the explosion of explosives with different compositions has obvious specificity. The electromagnetic radiation intensity generated by the explosion of energetic materials has a strong correlation with the distance from the explosion center, and it decreases with the increase of the distance, and the decreasing range is large. The structure and detonation method of energetic materials can change the geometrical motion mode during the explosion, resulting in the non-uniformity of electromagnetic radiation propagation.
ARTICLE | doi:10.20944/preprints202112.0245.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: radiotherapy electron beams; output factors; tubular applicator; solid-state detector
Online: 14 December 2021 (15:55:57 CET)
High-energy small electron beams generated by linear accelerators are used for radiotherapy of localized superficial tumors. The aim of the present study is to assess the dosimetric performance under small radiation therapy electron beams of the novel PTW microSilicon detector by comparison with commercially available dosimeters. Relative dose measurements of circular fields with 20, 30, 40 and 50 mm aperture diameters were performed for 4 to 12 MeV energy range of electron beams generated by an Elekta Synergy linac. Percentage depth dose, transverse profiles and output factors normalized to the 10 × 10 cm2 reference field were measured. All dosimetric data were collected in a PTW MP3 motorized water phantom at SSD of 100cm by using the novel PTW microSilicon detector. The PTW diode E and the PTW microDiamond were also used in all beam aperture for benchmarking. Data for the biggest field size were also measured by the PTW Advanced Markus ionization chamber.Measurements performed by the microSilicon are in good agreement with the reference values for all the tubular applicators and beam energies, within the stated uncertainties. This confirms the reliability of the microSilicon detector for relative dosimetry of small radiation therapy electron beams collimated by tubular applicators.
ARTICLE | doi:10.20944/preprints202111.0521.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Multi-beam profile fast test method; Phased array antenna; Source reconstruction; Antenna test method
Online: 29 November 2021 (11:34:30 CET)
The testing requirements of the active phased array antennas are very different from those of traditional passive antennas, due to its beam steering capability. Usually, each beam profile of the active phased array needs a separate radiation pattern test, which makes the overall testing time extremely long. Thus the traditional antenna test method can no longer meet the efficiency and cost requirements of new active phased array antennas test. In this paper, a fast test method tailored for phased array antennas is proposed that offers significantly reduced testing time at the expense of slight sacrifice of the accuracy. Using the simulated element pattern in array and ideal port excitation, the beam profile in any direction can be predicted by testing only a certain beam profile. Through theoretical derivation and experiments, the effectiveness of the method is verified, and the testing efficiency of the phased array antenna is demonstrated to be improved by ten times or even more.
ARTICLE | doi:10.20944/preprints202108.0018.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: deep reinforcement learning; source search and localization; active search; gamma radiation; source parameter estimation; sequential decision making; non-convex environment}
Online: 2 August 2021 (11:14:24 CEST)
Rapid search and localization for nuclear sources can be an important aspect in preventing human harm from illicit material in dirty bombs or from contamination. In the case of a single mobile radiation detector, there are numerous challenges to overcome such as weak source intensity, multiple sources, background radiation, and the presence of obstructions, i.e., a non-convex environment. In this work, we investigate the sequential decision making capability of deep reinforcement learning in the nuclear source search context. A novel neural network architecture (RAD-A2C) based on the actor critic (A2C) framework and a particle filter gated recurrent unit for localization is proposed. Performance is studied in a randomized 20 x 20 m convex and non-convex environment across a range of signal-to-noise ratio (SNR)s for a single detector and single source. RAD-A2C performance is compared to both an information-driven controller that uses a bootstrap particle filter and to a gradient search (GS) algorithm. We find that the RAD-A2C has comparable performance to the information-driven controller across SNR in a convex environment and at lower computational complexity per action. The RAD-A2C far outperforms the GS algorithm in the non-convex environment with greater than 95% median completion rate for up to seven obstructions.
ARTICLE | doi:10.20944/preprints202107.0282.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: PADC; poly(allyl diglycol carbonate); latent track; track core radius; G value; layered structure; REFIT; NISE; detection threshold; chemical criterion
Online: 13 July 2021 (09:34:32 CEST)
Modified structure along latent tracks and track formation process have been investigated in poly(allyl diglycol carbonate), PADC, which is well recognized as a sensitive etched track detector. This knowledge is essential to develop novel detectors with improved track registration property. The track structures of protons and heavy ions (He, C, Ne, Ar, Fe, Kr and Xe) have been examined by means of FT-IR spectrometry, covering the stopping power region between 1.2 to 12,000 eV/nm. Through a set of experiments on low-LET radiations – such as gamma ray -, multi-step damage process by electron hits was confirmed in the radiation-sensitive parts of the PADC repeat-unit. From this result, we unveiled for the first-time the layered structure in tracks, in relation with the number of secondary electrons. We also proved that etch pit was formed when at least two repeat-units were destroyed along the track radial direction. To evaluate the number of secondary electrons around tracks, a series of numerical simulations were performed with Geant4-DNA. Therefore, we are proposing new physical criterions to describe the detection thresholds. Futhermore, we propose a present issue of the definition of detection threshold for semi-relativistic C ions. And as a possible chemical criterion, formation density of hydroxyl group is suggested to express the response of PADC.
ARTICLE | doi:10.20944/preprints201907.0269.v3
Subject: Physical Sciences, Radiation And Radiography Keywords: Computed Tomography; radiation dose; cancer risk; CTPA; effective diameter
Online: 3 January 2020 (11:21:25 CET)
This study aims to evaluate the patient’s dose exposure from Computed Tomography Pulmonary Angiography (CTPA) examination and to estimates the cancer risk induced from the examinations based on the patient’s size. One hundred patients were recruited, and data information was collected retrospectively. A multi-detector (MDCT) (Philips Brilliance 128, USA) scanner were utilized for the CTPA examination, and dose data were obtained from the system. The effective diameter of each subjects’ image was measured for the Size-specific dose estimates (SSDEs). All subjects divided into Group 1 (19 – 25 cm), Group 2 (25-28 cm) and Group 3 (28-38 cm), where the association between gender were analysed. Effective dose (E), SSDE, organ dose and cancer risk of each group were evaluated and compared statistically using independent t-test and one-way ANOVA. The range of mean CTDIvol, DLP and E values were (6.44 – 17.42 mGy), (239 – 631 mGy), (5.19 – 13.90 mSv), respectively. In respective with the patient’s effective diameter, the mean SSDE value for Group 1, Group 2 and Group 3 were 9.93 ± 3.89 mGy, 13.70 ± 9.04 mGy and 22.29 ± 7.35 mGy. The organ dose and cancer risk attained for breast, lung and liver were 17.05 ± 10.40 mGy (194 per one million procedure), 17.55 ± 10.86 mGy (192 per one million procedure) and 15.04 ± 9.75 mGy (53 per one million procedure), respectively. Lung and breast with more massive patient’s effective diameter received the highest dose exposure which increases the probability of the cancer risk. CTDIvol was found to be underestimated, and SSDE provides more accurate in describing the radiation dose and cancer risk. Body effective diameter found to be significant on the estimation except for gender. Therefore, it is essential to apply optimised protocols in order to reduce patient’s exposure during CTPA examination.
Subject: Physical Sciences, Radiation And Radiography Keywords: radiation track chemistry; chemical track structure; oxygen effect; oxygen depletion; ion beam therapy; ROS; superoxide anion
Online: 5 December 2019 (03:32:18 CET)
The radiosensitivity of biological systems is strongly affected by the system oxygenation. On the nanoscopic scale and molecular level, this effect is considered to be strongly related to the indirect damage of radiation. Even though particle track radiolysis has been the object of several studies, still little is known about the nanoscopic impact of target oxygenation on the radical yields. We present here an extension of the chemical module of the Monte Carlo particle track structure code TRAX, taking into account the presence of dissolved molecular oxygen in the target material. The impact of the target oxygenation level on the chemical track evolution and the yields of all the relevant chemical species is studied in water under different irradiation conditions: different linear energy transfer (LET) values, different oxygenation levels, and different particle types. Especially for low LET radiation, a large production of two highly toxic species (HO2• and O2•− ), which are not produced in anoxic conditions, is predicted and quantified in oxygenated solutions. The remarkable correlation between the HO2• and O2•− production yield and the oxygen enhancement ratio observed in biological systems suggests a direct or indirect involvement of HO2• and O2•− in the oxygen sensitization effect. The results are in agreement with available experimental data and previous computational approaches. An analysis of the oxygen depletion rate in different radiation conditions is also reported.
ARTICLE | doi:10.20944/preprints201910.0168.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: neutron imaging; neutron detector; X-ray detector; CCD camera; CMOS camera; collimator; X-rays; image processing; computed tomography; CT reconstruction
Online: 15 October 2019 (11:15:26 CEST)
Neutron computed tomography (nCT) has been established at many major neutron sources worldwide, using high-end equipment requiring major investment and development. Many older and smaller reactors would be capable of doing nCT as well, but cannot afford the investment before feasibility is proven. We have developed a compact low-cost but high-quality detection system using a new cooled CMOS camera that can either be fully integrated into a sophisticated setup, or used with a rudimentary CT control and motion system to quickly evaluate feasibility of neutron CT at a given beam line facility. Exchanging the scintillation screen makes it feasible for X-rays as well, even for visible light (and transparent samples) using a matte screen. The control system uses a hack to combine motion control with existing imaging software so it can be used to test several dozen different cameras without writing specific drivers. Freeware software can do reconstruction and 3D imaging.
REVIEW | doi:10.20944/preprints201906.0231.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: bystander effect, genomic instability, lethal mutations,radiotherapy, diagnostic radiology
Online: 24 June 2019 (08:34:26 CEST)
Non-targeted effects (NTE) such as bystander effects or genomic instability have been known for many years but their significance for radiotherapy or medical diagnostic radiology are far from clear. Central to the issue are reported differences in response of normal and tumour tissues to signals from directly irradiated cells. This review will discuss possible mechanisms and implications of these different responses and will then discuss possible new therapeutic avenues suggested by the analysis. Finally, the importance of NTE for diagnostic radiology and nuclear medicine which stems from the dominance of NTE in the low dose region of the dose response curve will be presented. Areas such as second cancer induction and microenvironment plasticity will be discussed.
ARTICLE | doi:10.20944/preprints201805.0386.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: magnetic resonance imaging; arterial spin labelling; renal MRI; perfusion; renal ASL
Online: 28 May 2018 (06:26:31 CEST)
Purpose: A number of imaging readout schemes have been proposed for renal arterial spin labelling (ASL) to quantify kidney cortex perfusion, including gradient echo based methods of balanced fast field echo (bFFE) and gradient-echo echo-planar imaging (GE-EPI), or spin echo based schemes of spin-echo echo planar imaging (SE-EPI) and turbo spin-echo (TSE). Here, we compare these imaging schemes to evaluate the optimal imaging scheme for pulsed ASL (PASL) assessment of human kidney cortex perfusion at 3 T. Methods: Ten healthy volunteers with normal renal function were scanned using each 2D multislice imaging scheme, in combination with a respiratory triggered FAIR (flow-sensitive alternating inversion recovery) ASL scheme on a 3 T Philips Achieva scanner. All volunteers returned for a second identical scan session within two weeks of the first scan session. Comparisons were made between the imaging schemes in terms of perfusion weighted image (PWI) signal-to-noise ratio (SNR) and perfusion quantification, temporal SNR (tSNR), spatial coverage, and repeatability. Results: For each imaging scheme, renal cortex perfusion was calculated (bFFE: 276 ± 29 mL/100 g/min, GE-EPI: 222 ± 18 mL/100 g/min, SE-EPI: 201 ± 36 mL/100 g/min, TSE: 200 ± 20 mL/100 g/min). Perfusion was found to be higher for GE based readouts compared to SE based readouts, with significantly higher measured perfusion for the bFFE readout compared to all other schemes (P < 0.05), attributed to the greater vascular signal present. Despite the PWI-SNR being significantly lower for SE-EPI compared to all other schemes (P < 0.05), the SE-EPI readout gave the highest tSNR and was found to be the most reproducible scheme for the assessment of kidney cortex, with a CoV of 17.2%, whilst minimizing variability of the perfusion weighted signal across slices for whole kidney perfusion assessment. Conclusion: For the assessment of kidney cortex perfusion, SE-EPI provides optimal tSNR, minimal variability across slices and repeatable data acquired in a short scan time with low specific absorption rate.
ARTICLE | doi:10.20944/preprints201805.0176.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: gel dosimetry; radiation dosimetry; radio-fluorogenic gel, luminescent dosimetry
Online: 11 May 2018 (05:29:00 CEST)
In radiotherapy, accurate deposition of energy to the targeted volume is vital to ensure effective treatment. Gel dosimeters are attractive detection systems, as tissue substitutes with potential to yield three-dimensional dose distributions. Radio-fluorogenesis is creation fluorescent chemical products in response to energy deposition from high-energy radiation. This report shares studies of a radio-fluorogenic gel dosimetry system, gelatin with coumarin-3-carboxlyic acid (C3CA), for the quantification of imparted energy. Aqueous solutions exposed to ionizing radiation result in the production of hydroxyl free radicals through water radiolysis. Interactions between hydroxyl free radicals and coumarin-3-carboxylic acid produce a fluorescent product. 7-hydroxy-coumarin-3-carboxylic acid has a blue (445 nm) emission, following UV to near UV (365–405 nm) excitation. Effects of C3CA concentration and pH buffers were investigated for this system. The response of the system was explored with respect to strength, type, and exposure rate of high-energy radiation. Results show a linear dose response relationship with a dose-rate dependency and no energy or type dependencies. This report supports the utility of gelatin-C3CA for phantom studies of radio-fluorogenic processes.
ARTICLE | doi:10.20944/preprints201607.0009.v1
Subject: Physical Sciences, Radiation And Radiography Keywords: Antennas; Communication systems; Electromagnetic analysis; Measurements; Radio propagation; Waveguides
Online: 8 July 2016 (03:44:51 CEST)
In this research paper, design and development of pyramidal horn antenna for J-band application is reported. It is particularly designed for 17 dB gain and half beam width about 25 degrees at 6.93 GHz. Horn aperture, horn axial length and distance from the throat of the antenna to aperture are the main design constraints which are calculated and used for the antenna design and simulation. Beam width in E-plane and H-plane horn is calculated and it is 19.18 dB and 22.86 dB respectively. The reported antenna design shows good performance for J-band in radiometry, satellite, and radar applications.