Radiation And Environmental Biophysics[JOURNAL]
Sun
200 papers
Abrasive challenge effects on enamel and dentin from irradiated human teeth: an in vitro study.
Arid J, Palma-Dibb RG, Molena KF … +8 more , Faraoni JJ, Fillus TM, Tanimoto HM, Ranieri ALP, Paula-Silva FWG, Nelson-Filho P, de Macedo LD, Queiroz AM
Radiat Environ Biophys · 2024 Nov · PMID 39377786 · Publisher ↗
This study aimed to evaluate the effects of radiotherapy (RT) and chemoradiotherapy (CRT) on the wear and surface roughness of in vitro irradiated human enamel and dentin subjected to abrasive challenge. Enamel and denti...
This study aimed to evaluate the effects of radiotherapy (RT) and chemoradiotherapy (CRT) on the wear and surface roughness of in vitro irradiated human enamel and dentin subjected to abrasive challenge. Enamel and dentin specimens (n = 42) were prepared from teeth donated by healthy patients and those with head and neck cancer who had received radiotherapy (RT) or chemoradiotherapy (CRT). The specimens were categorized into three groups: control, RT, and CRT (n = 14 per group for both enamel and dentin). These samples were subjected to an in vitro abrasive experiment using a brushing machine, followed by wear and surface roughness assessments with a confocal laser scanning microscope conducted before and after the abrasive challenge, considering both exposed and non-exposed areas. Statistical analysis used Shapiro-Wilk tests for normality, Wilcoxon tests for comparing two means, and Kruskal-Wallis tests. A significance level of 5% was adopted. In enamel specimens, wear profile values of CRT and RT groups were not different from the control (p > 0.05). The RT group presents lower step values than the CRT and control groups (p < 0.001). No significant difference in final surface roughness was observed in all groups (p > 0.05). In dentin specimens, no significant difference in wear profile and step was observed in all groups (p > 0.05). However, CRT and RT groups present higher values in final surface roughness (p < 0.001). The exposure to ionizing radiation (associated or not to chemotherapy) influenced the surface roughness of dentin and the wear (step) of enamel after the in vitro abrasive challenge.Trial registration: Ethical procedures were approved by the FORP/USP Research Ethics Committee (CAAE: 61308416.4.0000.5419), and Hospital do Câncer de Barretos/Fundação Pio XII (CAAE: 61308416.4.3001.5437).
The system of radiological protection and the UN sustainable development goals.
Rühm W, Applegate K, Bochud F … +12 more , Laurier D, Schneider T, Bouffler S, Cho K, Clement C, German O, Hirth G, Kai M, Liu S, Mayall A, Romanov S, Wojcik A
Radiat Environ Biophys · 2024 Nov · PMID 39254690 · Full text
In 2015 the United Nations issued 17 Sustainable Development Goals (SDGs) addressing a wide range of global social, economic, and environmental challenges. The main goal of this paper is to provide an understanding of ho...
In 2015 the United Nations issued 17 Sustainable Development Goals (SDGs) addressing a wide range of global social, economic, and environmental challenges. The main goal of this paper is to provide an understanding of how the current System of Radiological Protection relates to these SDGs. In the first part it is proposed that the current System of Radiological Protection is implicitly linked to sustainable development. This is substantiated by analysing the features of the current System as set out by the International Commission on Radiological Protection (ICRP) in its publications. In the second part it is proposed that sustainability should be considered and more explicitly addressed in the next ICRP general recommendations, as part of the currently ongoing review and revision of the current System. A few examples are given of how this could be realised, and it is proposed that this issue should be discussed and developed together with the international community interested in radiological protection.
The scientific nature of the linear no-threshold (LNT) model used in the system of radiological protection.
Wojcik A, Zölzer F
Radiat Environ Biophys · 2024 Nov · PMID 39222266 · Full text
During the first half of the 20th century, it was commonly assumed that radiation-induced health effects occur only when the dose exceeds a certain threshold. This idea was discarded for stochastic effects when more know...
During the first half of the 20th century, it was commonly assumed that radiation-induced health effects occur only when the dose exceeds a certain threshold. This idea was discarded for stochastic effects when more knowledge was gained about the mechanisms of radiation-induced cancer. Currently, a key tenet of the international system of radiological protection is the linear no-threshold (LNT) model where the risk of radiation-induced cancer is believed to be directly proportional to the dose received, even at dose levels where the effects cannot be proven directly. The validity of the LNT approach has been questioned on the basis of a claim that only conclusions that can be verified experimentally or epidemiologically are scientific and LNT should, thus, be discarded because the system of radiological protection must be based on solid science. The aim of this publication is to demonstrate that the LNT concept can be tested in principle and fulfils the criteria of a scientific hypothesis. The fact that the system of radiological protection is also based on ethics does not render it unscientific either. One of the fundamental ethical concepts underlying the LNT model is the precautionary principle. We explain why it is the best approach, based on science and ethics (as well as practical experience), in situations of prevailing uncertainty.
Evaluation of the conformity of intensity-modulated radiation therapy and volumetric modulated arc therapy using AAPM TG 119 protocol.
Tam DTM, Ho PL, Uy PQ … +8 more , Hieu NT, Linh VT, Hoa NT, Lam NTT, Nga BTT, Thanh TH, Thanh TT, Tao CV
Radiat Environ Biophys · 2024 Nov · PMID 39153061 · Publisher ↗
The aim of this work was to evaluate the conformity of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), and verify the accuracy of the planning and delivery system used in this wo...
The aim of this work was to evaluate the conformity of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT), and verify the accuracy of the planning and delivery system used in this work based on the AAPM TG-119 protocol. The Eclipse 13.6 treatment planning system (TPS) was used to plan the TG-119 test suite, which included four test cases: MultiTarget, Prostate, Head/Neck, and C-Shape for IMRT and VMAT techniques with 6 MV and 10 MV acceleration voltages. The results were assessed and discussed in terms of the TG-119 protocol and the results of previous studies. In addition, point dose and planar dose measurements were done using a semiflex ion chamber and an electronic portal imaging device (EPID), respectively. The planned doses of all test cases met the criteria of the TG-119 protocol, except those for the spinal cord of the C-Shape hard case. There were no significant differences between the treatment planning doses and the doses given in the TG-119 report, with p-values ranging from 0.974 to 1 (p > 0.05). Doses to the target volumes were similar in the IMRT and VMAT plans, but the organs at risk (OARs) doses were different depending on the test case. The planning results showed that IMRT is more conformal than VMAT in certain cases. For the point dose measurements, the confidence limit (CL) of 0.030 and 0.021 were better than the corresponding values of 0.045 and 0.047 given in the TG-119 report for high-dose and low-dose areas, respectively. Regarding the planar dose measurements, the CL value of 0.38 obtained in this work was lower than that given in the TG-119 report (12.4). It is concluded that the dosimetry measurements performed in this study showed better confidence limits than those provided in the TG 119 report. IMRT remains more conformal in certain circumstances than the more progressive VMAT. When selecting the method of delivering a dose to the patient, several factors must be considered, including the radiotherapy technique, energy, treatment site, and tumour geometry.
Thyroid cancer incidence in cohorts exposed in childhood to I released during the Windscale nuclear reactor accident at Sellafield, England, in 1957.
McNally RJQ, Wakeford R, Bunch KJ … +5 more , Hayes L, Vernon S, Jeffrey PA, Paley L, Elliott A
Radiat Environ Biophys · 2024 Nov · PMID 39150515 · Full text
A fire in one of the Windscale nuclear reactors at Sellafield (Cumbria, England) in October 1957 released 1,800 TBq of I (half-life, 8 days) to atmosphere. Measurements of I activity in thyroids of exposed children showe...
A fire in one of the Windscale nuclear reactors at Sellafield (Cumbria, England) in October 1957 released 1,800 TBq of I (half-life, 8 days) to atmosphere. Measurements of I activity in thyroids of exposed children showed typical thyroid doses of tens of milligray, but with some exceeding 100 mGy. Radiation exposure in childhood is known to increase the risk of thyroid cancer. Consequently, an investigation was conducted into whether raised numbers of thyroid cancer cases occurred in those exposed to I as young children in Cumbria. A database of Cumbrian births from 1950 onwards allowed cohorts of 56,086 births during 1950-1958 and 137,444 births during 1959-1980 to be constructed, periods including children potentially exposed and unexposed, respectively, to I. Three areas of Cumbria with different I contamination levels were identified from monitoring data, and births assigned to these three areas for the two periods of birth. Members of these six sub-cohorts were linked to incident thyroid cancer cases in Great Britain during 1981-2020 using national cancer registration databases, providing thyroid cancer incidence rates. Incidence rate ratios (IRRs), with the lowest contamination area as a reference, were computed. No IRR differed discernibly from unity. For births during 1950-1958, the IRR for the combined highest and intermediate I contamination areas was 0.68 (95% confidence interval: 0.24, 1.56), and no case of thyroid cancer was found in the small cohort born in the highest contamination area. In conclusion, no increased risk of thyroid cancer in those exposed to I as young children in Cumbria in 1957 was detected. This study adds to the evidence on the long-term risk of thyroid cancer following childhood exposure to low and moderate levels of I, such as occurred following the Fukushima nuclear accident in 2011.
Radiosensitization with metallic nanoparticles under MeV proton beams: local dose enhancement.
Mansouri E, Almisned G, Tekin HO … +2 more , Rajabpour S, Mesbahi A
Radiat Environ Biophys · 2024 Nov · PMID 39150514 · Publisher ↗
In addition to specific dosimetric properties of protons, their higher biological effectiveness makes them superior to X-rays and gamma radiation, in radiation therapy. In recent years, enrichment of tumours with metalli...
In addition to specific dosimetric properties of protons, their higher biological effectiveness makes them superior to X-rays and gamma radiation, in radiation therapy. In recent years, enrichment of tumours with metallic nanoparticles as radiosensitizer agents has generated high interest, with several studies attempting to confirm the efficacy of nanoparticles in proton therapy. In the present study Geant4 Monte Carlo (MC) code was used to quantify the increased nanoscopic dose deposition of 50 nm metallic nanoparticles including gold, bismuth, iridium, and gadolinium in water upon exposure to 5, 25, and 50 MeV protons. Dose enhancement factors, radial dose distributions in nano-scale, as well as secondary electron and photon energy spectra were calculated for the studied nanoparticles and proton beams. The obtained results demonstrated that in the presence of metallic nanoparticles an increase in proton energy leads to a decrease in secondary electron and photon production yield. Additionally, an increase in the radial dose enhancement factor from 1.4 to 16 was calculated for the studied nanoparticles when the proton energy was increased from 5 to 50 MeV. It is concluded that the dosimetric advantages of proton beams could be improved significantly in the presence of metallic nanoparticles.
(Re)integrating radioactive materials and waste into a global sustainable development context.
Wimmers A, Böse F, Beppler J … +3 more , Morawe P, Weber M, von Hirschhausen C
Radiat Environ Biophys · 2024 Nov · PMID 39120613 · Full text
The 17 Sustainable Development Goals (SDGs) of the United Nations, established in 2015, aim to achieve global sustainability by 2030 through the improvement of environmental, social, and economic parameters. However, unl...
The 17 Sustainable Development Goals (SDGs) of the United Nations, established in 2015, aim to achieve global sustainability by 2030 through the improvement of environmental, social, and economic parameters. However, unlike earlier concepts such as the Agenda 21 of 1992, the SDGs overlook radioactive waste management and related challenges of radiation itself. First, we investigate the historic consideration and unexplained disappearance of radioactive waste in earlier sustainability concepts. Then, we propose amending seven SDGs to address this gap. For SDGs 6 (Clean Water and Sanitation), 14 (Life Below Water), and 15 (Life on Land), new or revised indicators should monitor the release of hazardous materials. SDGs 9 (Industry, Innovation and Infrastructure), 16 (Peace, Justice and Strong Institutions), and 17 (Partnerships for the Goals) require additional targets and indicators to integrate international cooperation and social implications of nuclear facilities' operation. Redefining "hazardous waste" in SDG 12 (Responsible Consumption and Production) and "environmentally sound technologies" in SDG 17 is necessary to encompass radioactive waste. Implementing these changes demands statistical efforts, but the existing monitoring infrastructure, particularly in Europe and North America, can facilitate this. As 2030 approaches, it is crucial to reintroduce radioactive waste management into sustainability agendas, whether within the SDGs themselves or in a subsequent framework.
Pilot screening of potential matrikines resulting from collagen breakages through ionizing radiation.
Montanari J, Schwob L, Marie-Brasset A … +6 more , Vinatier C, Lepleux C, Antoine R, Guicheux J, Poully JC, Chevalier F
Radiat Environ Biophys · 2024 Aug · PMID 39115696 · Full text
Little is known regarding radiation-induced matrikines and the possible degradation of extracellular matrix following therapeutic irradiation. The goal of this study was to determine if irradiation can cut collagen prote...
Little is known regarding radiation-induced matrikines and the possible degradation of extracellular matrix following therapeutic irradiation. The goal of this study was to determine if irradiation can cut collagen proteins at specific sites, inducing potentially biologically active peptides against cartilage cells. Chondrocytes cultured as 3D models were evaluated for extracellular matrix production. Bystander molecules were analyzed in vitro in the conditioned medium of X-irradiated chondrocytes. Preferential breakage sites were analyzed in collagen polypeptide by mass spectrometry and resulting peptides were tested against chondrocytes. 3D models of chondrocytes displayed a light extracellular matrix able to maintain the structure. Irradiated and bystander chondrocytes showed a surprising radiation sensitivity at low doses, characteristic of the presence of bystander factors, particularly following 0.1 Gy. The glycine-proline peptidic bond was observed as a preferential cleavage site and a possible weakness of the collagen polypeptide after irradiation. From the 46 collagen peptides analyzed against chondrocytes culture, 20 peptides induced a reduction of viability and 5 peptides induced an increase of viability at the highest concentration between 0.1 and 1 µg/ml. We conclude that irradiation promoted a site-specific degradation of collagen. The potentially resulting peptides induce negative or positive regulations of chondrocyte growth. Taken together, these results suggest that ionizing radiation causes a degradation of cartilage proteins, leading to a functional unbalance of cartilage homeostasis after exposure, contributing to cartilage dysfunction.
Administration of low dose intranasal ketamine exerts a neuroprotective effect on whole brain irradiation injury model in wistar rats.
Yaprak G, Çini N, Atasoy ÖB … +3 more , Uyanikgil Y, Erdogan MA, Erbaş O
Radiat Environ Biophys · 2024 Aug · PMID 39066789 · Publisher ↗
Exposure to ionizing radiation leads to oxidative stress and neuroinflammation, resulting in neurocognitive impairments. Adverse effects are also associated with glutamate-induced excitotoxicity due to alterations in the...
Exposure to ionizing radiation leads to oxidative stress and neuroinflammation, resulting in neurocognitive impairments. Adverse effects are also associated with glutamate-induced excitotoxicity due to alterations in the composition of glutamate receptors. Ketamine, which is a noncompetitive NMDA glutamate receptor antagonist, has been stated to exert an impact on glutamatergic receptors. This study aims to reveal the possible alleviating or preventive effects of ketamine, which maintains glutamate homeostasis and decreases neurodegeneration, in a radiation-induced neurotoxicity model. Twenty-one female Wistar Queryrats were included in the study and 14 of these underwent whole brain irradiation (IR) with a 20 Gray single dose. Animals were allocated into three groups. Group 1: Normal control; Group 2: Placebo / IR + Saline; Group 3: IR + Ketamine. Ketamine was administered in addition to IR to rats in Group 3. The one-way ANOVA statistical test was used to compare groups. The value of p < 0.05 was considered statistically significant. When administered in addition to irradiation, ketamine treatment significantly increased scores in the three-chamber sociability test, open field test, and passive avoidance learning test. It also raised neuron counts in the hippocampal CA1 and CA3 regions as well as in Purkinje cells, and enhanced levels of brain-derived neurotrophic factor and tyrosine receptor kinase-B. Furthermore, ketamine administration resulted in decreased levels of glial fibrillary acidic protein, malondialdehyde, and tumor necrosis factor-alpha, indicating a reduction in neuroinflammation and oxidative stress. Ketamine exerted a significant protective impact on radiation-induced neurocognitive impairments and enhanced social-memory capacity by reducing neuronal loss, oxidative stress, and neuroinflammation. Our findings suggest that ketamine is beneficial in the treatment or prevention of neurodegeneration via the regulation of the BDNF/TrkB signaling pathway besides decreasing neuroinflammation and blocking NMDA receptors.
Effective dose assessment due to inhalation of Rn, Rn, and their progeny: highlighting the major contribution of thoron in a thoron-prone area in Cameroon.
Djeufack LB, Hamadou I, Kranrod C … +5 more , Mishra R, Hosoda M, Sapra BK, Saïdou, Tokonami S
Radiat Environ Biophys · 2024 Aug · PMID 39033202 · Publisher ↗
To assess public exposure to radon, thoron, and their progeny, measurements were conducted in 50 dwellings within the bauxite-rich area of Fongo-Tongo in western Cameroon. Passive integrating radon-thoron discriminative...
To assess public exposure to radon, thoron, and their progeny, measurements were conducted in 50 dwellings within the bauxite-rich area of Fongo-Tongo in western Cameroon. Passive integrating radon-thoron discriminative detectors (specifically RADUET) were employed for radon and thoron measurements. Additionally, concentrations of short-lived radon and thoron progeny were estimated using Direct Radon Progeny Sensors (DRPSs) and Direct Thoron Progeny Sensors (DTPSs) based on LR-115 detectors. The findings revealed indoor radon concentrations ranging from 31 to 123 Bq m with a geometric mean (GM) of 62 Bq m, and indoor thoron concentrations ranging from 36 to 688 Bq m with a GM of 242 Bq m. The Equilibrium Equivalent Radon Concentration (EERC) ranged from 3 to 86 Bq m with a GM of 25 Bq m, while the Equilibrium Equivalent Thoron Concentration (EETC) ranged from 1.2 to 12.5 Bq m with a GM of 7.6 Bq m. Notably, all dwellings recorded radon concentrations below 100 Bq m. Arithmetic means of radon and thoron equilibrium factors were calculated as 0.47 and 0.04, respectively. To assess annual effective doses from radon and thoron inhalation, equilibrium factors were used along with direct measurements of EERC and EETC. The differences observed in annual effective doses were 4.5% for radon and 42.5% for thoron. Furthermore, the contribution of thoron and its decay products to the annual effective dose from radon, thoron, and their progeny ranged from 12 to 94%, with an average contribution of 58%. Thus, this study found that the effective dose due to thoron inhalation in the study area exceeded that due to radon inhalation. It is concluded that, when evaluating radiation doses and health risks, it is crucial to consider both thoron and its progeny alongside radon and its progeny. This underscores the importance of considering direct measurements for accurately estimating radiation doses.
Thyroid ultrasound findings in young and middle-aged adults living in the region of the Chornobyl Nuclear Power Plant.
Zabirova A, Saiko A, Orita M … +3 more , Furuya F, Yamashita S, Takamura N
Radiat Environ Biophys · 2024 Aug · PMID 39031188 · Full text
Nearly forty years have passed since the Chornobyl Nuclear Power Plant accident, which resulted in childhood and adolescent thyroid cancers increasing due to internal exposure to iodine-131. Therefore, the Fukushima Daii...
Nearly forty years have passed since the Chornobyl Nuclear Power Plant accident, which resulted in childhood and adolescent thyroid cancers increasing due to internal exposure to iodine-131. Therefore, the Fukushima Daiichi Nuclear Power Station accident, in 2011, raised serious anxiety about potential risks of thyroid cancers. Considering the causal relationship between thyroid cancer and the Chornobyl accident, radiation dose to the thyroid due to this accident should be considered carefully. In addition, a thorough investigation of any influence of ultrasound screening of the thyroid on the detection of thyroid diseases was still missing. Consequently, from 2019 to 2021, the frequency of abnormal thyroid findings from screening of residents in Zhytomyr, Ukraine, which was heavily contaminated by the accident, was evaluated in this study. For this, the same diagnostic classification of any thyroid ultrasound findings as those of the Fukushima Health Management Survey were used. This classification used the categories "A1" (no findings), "A2" (thyroid cysts less than 20 mm and/or thyroid nodules less than 5 mm), and "B" (thyroid cysts more than 20 mm and/or thyroid nodules more than 5 mm). 2,978 participants were analyzed. It was found that the frequency of "B" findings increased with age. This may be due to the observed increased incidence of not only malignant but also benign thyroid nodules. It may well be that such an increase will also be observed in Fukushima in the future. It is concluded that future thyroid examiners in Fukushima should be aware of findings specific to adults, such as chronic thyroiditis. For comparison, it will be necessary to perform longitudinal studies in the Japanese population not exposed to radiation from the Fukushima accident.
Actinium-225 as an example for monitoring of internal exposure of occupational intakes of radionuclides in face of new nuclear-medical applications for short-lived alpha emitting particles.
Hartmann S, Taubner K, Vogt T … +5 more , Meisenberg O, Schkade UK, Steyer C, Meckel M, Kesenheimer C
Radiat Environ Biophys · 2024 Aug · PMID 39031187 · Full text
Monitoring of internal exposure to short-lived alpha-emitting radionuclides such as actinium-225 (Ac), which are becoming increasingly important in nuclear medicine, plays an important role in the radiation protection of...
Monitoring of internal exposure to short-lived alpha-emitting radionuclides such as actinium-225 (Ac), which are becoming increasingly important in nuclear medicine, plays an important role in the radiation protection of occupationally exposed persons. After having tested gamma spectrometry, liquid scintillation counting and alpha spectrometry for monitoring of internal exposure, the focus of the present study was on solid phase extraction of Ac from urine in combination with alpha spectrometry. The development of the method was based on recent findings from the literature on this topic. The method was used in a pilot phase to monitor internal exposure of four workers who were directly or indirectly involved in the manufacture and/or use of Ac. The monitoring protocol allowed a relatively short 24-hour urine sample analysis with excellent recovery of the internal standard, but it did not allow for a detection limit of less than 1 mBq nor a sufficient yield of Ac. Based on these results it is concluded that an in vitro excretion analysis alone is not appropriate for monitoring internal exposure to Ac. Instead, different radiation monitoring techniques have to be combined to ensure the radiation protection of employees.
Quantitative stakeholder-driven assessment of radiation protection issues via a PIANOFORTE online survey.
Groma V, Madas B, Rauser F … +9 more , Birschwilks M, Blume A, Real A, Murakas R, Michalik B, Paiva I, Sjømoen TM, Tkaczyk AH, Popic JM
Radiat Environ Biophys · 2024 Aug · PMID 39020222 · Full text
To enhance stakeholder engagement and foster the inclusion of interests of citizens in radiation protection research, a comprehensive online survey was developed within the framework of the European Partnership PIANOFORT...
To enhance stakeholder engagement and foster the inclusion of interests of citizens in radiation protection research, a comprehensive online survey was developed within the framework of the European Partnership PIANOFORTE. This survey was performed in 2022 and presented an opportunity for a wide range of stakeholders to voice their opinions on research priorities in radiation protection for the foreseeable future. Simultaneously, it delved into pertinent issues surrounding general radiation protection. The PIANOFORTE e-survey was conducted in the English language, accommodating a diverse range of participants. Overall, 440 respondents provided their insights and feedback, representing a broad geographical reach encompassing 29 European countries, as well as Canada, China, Colombia, India, and the United States. To assess the outcomes, the Positive Matrix Factorization numerical model was applied, in addition to qualitative and quantitative assessment of individual responses, enabling the discernment of four distinct stakeholder groups with varying attitudes. While the questionnaire may not fully represent all stakeholders due to the limited respondent pool, it is noteworthy that approximately 70% of the participants were newcomers to comparable surveys, demonstrating a proactive attitude, a strong willingness to collaborate and the necessity to continuously engage with stakeholder groups. Among the individual respondents, distinct opinions emerged particularly regarding health effects of radiation exposure, medical use of radiation, radiation protection of workers and the public, as well as emergency and recovery preparedness and response. In cluster analysis, none of the identified groups had clear preferences concerning the prioritization of future radiation protection research topics.
Patient dose and associated exposure parameters in pelvic x-ray examinations: dependence on radiographic system.
Welarathna S, Velautham S, Sarasanandarajah S
Radiat Environ Biophys · 2024 Aug · PMID 39020221 · Publisher ↗
Technological differences between computed radiography (CR) and digital radiography (DR) systems can influence patient doses and exposure parameters in pelvic x-ray examinations. The presence of radiosensitive organs in...
Technological differences between computed radiography (CR) and digital radiography (DR) systems can influence patient doses and exposure parameters in pelvic x-ray examinations. The presence of radiosensitive organs in the pelvic region underscores the need to optimize these parameters for both CR and DR systems. This prospective study aimed to compare the patient doses and exposure parameters for adult patients undergoing pelvic x-ray examinations using CR and DR systems, based on data from Sri Lanka. The study included data from 56 x-ray examinations, with 25 using CR and 31 using DR. Patient demographic characteristics and exposure parameters (kVp: kilovoltage peak, mAs: tube current-exposure time product) were recorded, and patient doses were measured in terms of the kerma-area product (P) using a P meter. Despite similar mean weight and body mass index (BMI), the CR systems showed significantly higher mean kVp (7.4%), mAs (16.4%), and P (29.7%) than the DR systems (CR - kVp: 73.2, mAs: 37.8, P: 2.29 Gy cm; DR - kVp: 67.8, mAs: 31.6, P: 1.61 Gy cm). The Mann-Whitney U test revealed statistically significant differences in P and kVp between the CR and DR systems (p < 0.05). Furthermore, even with lower patient weight and BMI, the mean mAs and P in this study were substantially higher than those reported in the literature for both CR and DR systems. These results suggest the need to optimize current mAs settings for the studied hospitals and introduce radiographic system-specific exposure parameters and reference dose levels for pelvic x-ray examinations in order to enhance patient protection.
Reduction of detection limits in monitoring of internal exposures by a combined evaluation of emissions and spectra.
Meisenberg O
Radiat Environ Biophys · 2024 Aug · PMID 38980362 · Full text
Routine monitoring of internal exposures requires the detection of effective doses of at most 1 mSv per calendar year. For some radionuclides, this requirement cannot be satisfied by a conventional evaluation of the spec...
Routine monitoring of internal exposures requires the detection of effective doses of at most 1 mSv per calendar year. For some radionuclides, this requirement cannot be satisfied by a conventional evaluation of the spectra that are gained in alpha or gamma spectrometry. However, since several measurements are conducted per calendar year on a regular basis, a combined evaluation of measurements, i.e. the evaluation of sum spectra, is possible. Additionally, radionuclides that feature several emissions of alpha or gamma radiation allow a combined evaluation of their emissions. Both methods can lead to significantly smaller detection limits as compared to a separate evaluation of spectra in many cases. However, the variation of parameters that influence the evaluation such as the measurement efficiency, abundance and chemical yield requires specific calculations and treatments of the spectra as well as a manipulation of the channel contents: In a combination of emissions, energy regions are summed and evaluated with a combined efficiency that is weighted by the abundances. In a combination of spectra, the channel contents must be scaled by the ratio of the calibration factors before the summation of the spectra. In the routine monitoring of short-lived radionuclides that feature a variety of emissions such as Ac, these combinations are particularly effective in reducing the detectable annual effective dose. For alpha spectrometry of Ac, both methods applied together can lead to a detectable effective dose of about 1 mSv per year as compared to a dose of about 90 mSv with a conventional separate evaluation.
Stereotactic body radiation therapy for prostate cancer: a dosimetric comparison of IMRT and VMAT using flattening filter and flattening filter-free beams.
El-Sayed SM, El-Gebaly RH, Fathy MM … +1 more , Abdelaziz DM
Radiat Environ Biophys · 2024 Aug · PMID 38969869 · Publisher ↗
This retrospective study was performed to evaluate plan quality and treatment delivery parameters of stereotactic body radiation therapy (SBRT) for prostate cancer. The study utilized different isocentric modulated techn...
This retrospective study was performed to evaluate plan quality and treatment delivery parameters of stereotactic body radiation therapy (SBRT) for prostate cancer. The study utilized different isocentric modulated techniques: intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using 6 MV flattening filter (FF) and 10 MV flattening filter-free beams (FFF). Fifteen retrospective prostate cancer patients were selected for this study. Sixty plans were created with an SBRT-prescribed dose of 36.25 Gy delivered in five fractions. Planning target volume (PTV) coverage, plan quality indices, doses delivered to organs at risk (OARs), and treatment delivery parameters were compared for all plans. It turned out that VMAT plans, particularly those using the FFF beam, provided superior target conformality and a steeper dose gradient as compared to IMRT plans. Additionally, VMAT plans showed better OARs sparing compared to IMRT plans. However, IMRT plans delivered a lower maximum dose to the target than VMAT plans. Importantly, the VMAT plans resulted in reduced treatment delivery parameters, including beam on time (BOT), monitor unit (MU), and modulation factor (MF), compared to IMRT plans. Furthermore, a statistically significant difference was observed in BOT and mean body dose between FF and FFF beams, with FFF beams showing superior performance. Considering all results, VMAT using 10 MV (FFF) is suggested for treating prostate cancer patients with SBRT. This offers the fastest delivery in addition to maintaining the highest plan quality.
Note on dose conversion for radon exposure.
Beck TR
Radiat Environ Biophys · 2024 Aug · PMID 38884804 · Full text
The epidemiological approach to converting radon exposure to effective dose is examined. Based on the definition of the effective dose, the dose conversion is obtained from the equivalence of lung-specific detriment asso...
The epidemiological approach to converting radon exposure to effective dose is examined. Based on the definition of the effective dose, the dose conversion is obtained from the equivalence of lung-specific detriment associated with low-LET radiation and with radon exposure. This approach most reliably estimates effective dose per radon exposure on the basis of epidemiological data and implicitly includes the radiation weighting factor required to calculate the effective dose from radon exposure using the dosimetric approach, applying biokinetic and dosimetric models. Consistency between the results of the epidemiological and dosimetric approaches is achieved by using a radiation weighting factor of about 10 for alpha particles instead of the current ICRP value of 20. In contrast, the epidemiological approach implemented in ICRP 65, and referred to as dose conversion convention, was based on direct comparison of total radiation detriment with lung detriment from radon exposure. With the revision of radiation detriments in ICRP 103, this approach can be judged to overestimate the effective dose per radon exposure by about a factor of two because the tissue weighting factor for lung differs from the value of relative detriment to which it relates.
Home-made low-cost dosemeter for photon dose measurements in radiobiological experiments and for education in the field of radiation sciences.
Blomgren A, Tartas A, Meher PK … +3 more , Silverstein S, Wojcik A, Brzozowska B
Radiat Environ Biophys · 2024 Aug · PMID 38847828 · Full text
Reliable dosimetry systems are crucial for radiobiological experiments either to quantify the biological consequences of ionizing radiation or to reproduce results by other laboratories. Also, they are essential for dida...
Reliable dosimetry systems are crucial for radiobiological experiments either to quantify the biological consequences of ionizing radiation or to reproduce results by other laboratories. Also, they are essential for didactic purposes in the field of radiation research. Professional dosemeters are expensive and difficult to use in exposure facilities with closed exposure chambers. Consequently, a simple, inexpensive, battery-driven dosemeter was developed that can be easily built using readily available components. Measurements were performed to validate its readout with photons of different energy and dose rate and to demonstrate the applicability of the dosemeter. It turned out that the accuracy of the dose measurements using the developed dosemeter was better than 10%, which is satisfactory for radiobiological experiments. It is concluded that this dosemeter can be used both for determining the dose rates of an exposure facility and for educational purposes.
Radiation doses and diagnostic reference levels for common CT scans in adults in Northwest region of Iran.
Mardfar S, Ghaziyani MF, Mortezazadeh T … +3 more , Zamani H, Rahimiyan M, Khezerloo D
Radiat Environ Biophys · 2024 Nov · PMID 38839606 · Publisher ↗
This study aims to estimate organ dose and cancer risks, establish region-specific diagnostic reference levels (DRLs), and determine achievable doses (ADs) for common CT procedures in adults in the northwest of Iran. Eff...
This study aims to estimate organ dose and cancer risks, establish region-specific diagnostic reference levels (DRLs), and determine achievable doses (ADs) for common CT procedures in adults in the northwest of Iran. Effective and organ doses were estimated using VirtualDoseCT software in a sample of 480 adult patients who underwent head, sinus, chest, and abdomen-pelvis (AP) CT scans. The guidelines provided by the BEIR VII report were utilized to estimate cancer risks. Effective and organ doses for specific procedures were determined, with the highest mean organ dose being observed in the brain during head CT examinations, with a value of 54.02 mGy. It was observed that the lungs in chest examinations and the colon in AP examinations had the highest risk of cancer, with rates of 30.72 and 21.37 per 100,000 persons, respectively. Higher cancer risk values were generally exhibited by females compared to males. The DRLs for common CT examinations were established as follows: Head CT (CTDIvol 41 mGy, DLP 760 mGy cm), Sinus CT (CTDIvol 16 mGy, DLP 261 mGy cm), Chest CT (CTDIvol 8 mGy, DLP 287 mGy cm), and AP CT (CTDIvol 9 mGy, DLP 508 mGy cm). Significant variations in dose distribution among facilities were identified, indicating the need for optimization. The study highlights the importance of minimizing radiation exposure to critical organs and promoting patient safety in CT examinations. The establishment of region-specific DRLs and ADs can help optimize radiation doses and reduce cancer risks for patients.
Model of age-dependent dynamics and biokinetics of T-cells as natural biodosimeters.
Tolstykh EI, Vozilova AV, Akleyev AV … +1 more , Zalyapin VI
Radiat Environ Biophys · 2024 Aug · PMID 38829435 · Publisher ↗
Circulating T-lymphocytes are used as "natural biodosimeters" for estimating radiation doses, since the frequency of chromosomal aberrations induced in them is proportional to the accumulated dose. Moreover, stable chrom...
Circulating T-lymphocytes are used as "natural biodosimeters" for estimating radiation doses, since the frequency of chromosomal aberrations induced in them is proportional to the accumulated dose. Moreover, stable chromosomal aberrations (translocations) are detected years and decades after exposure. Internal incorporation of radionuclides often leads to non-uniform exposure, which resulted in difficulties in the application of retrospective biodosimetry using T-lymphocytes. Some properties of T-lymphocytes complicate retrospective biodosimetry in this case: (1) the thymic production of T-cells depends significantly on age, the maximum is observed in early childhood; (2) the "lymphocyte-dosimeter" accumulates changes (translocations) while circulating through the body. The objective of this paper is to describe the technical characteristics of the model of age dynamics and T-cell biokinetics and approaches to assessing the dose to circulating lymphocytes under various exposure scenarios. The model allows to quantify the fractions of T-lymphocytes that were formed before and after exposure. The model takes into account the time fractions that circulating lymphocytes spend in various lymphoid organs. Age-related thymic involution was also considered. The model predicts that after internal exposure to Sr, the doses to T-lymphocytes can differ significantly from the doses to the bone marrow and other tissues. For uniform external γ-exposure, and for internal exposure due to non-bone -seeking radionuclides (for example, Ce), predicted doses to T-lymphocytes are very close to bone marrow doses. The model allows to quantify the correction factors for FISH-based doses to obtain doses to organs and tissues.
About
- Frequency
- Sun
- Papers found
- 200
- RSS feed
- Subscribe