Estimated Radiation Dose Research Articles

Application of FISH based G2-PCC assay for the cytogenetic assessment of high radiation dose exposures: Potential implications for rapid triage biodosimetry.

The main goal of this study is to test the utility of calyculin A induced G2-PCC assay as a biodosimetry triage tool for assessing a wide range of low and acute high radiation dose exposures of photons. Towards this initiative, chromosome aberrations induced by low and high doses of x-rays were evaluated and characterized in G2-prematurely condensed chromosomes (G2-PCCs) by fluorescence in situ hybridization (FISH) using human centromere and telomere specific PNA (peptide nucleic acid) probes. A dose dependent increase in the frequency of dicentric chromosomes was observed in the G2-PCCs up to 20 Gy of x-rays. The combined yields of dicentrics and rings in the G2-PCCs showed a clear dose dependency up to 20 Gy from 0.02/cell for 0.1 Gy to 14.98/cell for 20 Gy. Centric rings were observed more frequently than acentric ring chromosomes in the G2-PCCs at all the radiation doses from 1 Gy to 20 Gy. A head-to-head comparison was also performed by FISH on the yields of chromosome aberrations induced by different doses of x-rays (0 Gy -7.5 Gy) in colcemid arrested metaphase chromosomes and calyculin A induced G2-PCCs. In general, the frequencies of dicentrics, rings and acentric fragments were slightly higher in G2-PCCs than in colcemid arrested metaphase chromosomes at all the radiation doses, but the differences were not statistically significant. To reduce the turnaround time for absorbed radiation dose estimation, attempt was made to obtain G2-PCCs by reducing the culture time to 36 hrs. The absorbed doses estimated in x-rays irradiated (0,1,2 and 4 Gy) G2-PCCs after 36 hrs of culture were grossly like that of G2-PCCs and colcemid arrested metaphase chromosomes prepared after 48 hrs of culture. Our study indicates that the shortened version of calyculin A induced G2-PCC assay coupled with the FISH staining technique can serve as an effective triage biodosimetry tool for large-scale radiological/nuclear incidents.

Estimation of the Effective Radiation Dose in Nuclear Medicine Workers from Dhaka by Measuring Radioactivity in Urine Sample Resulting from Internal Exposure

This study estimates the effective doses and activity concentration from 151 urine samples which are collected from 15 (Fifteen) occupational workers at National Institute of Nuclear Medicine and Allied Science (NINMAS) in Dhaka, Bangladesh. The radioactivity concentration in urine sample is due to intake of I-131, Tc-99m and F-18. The samples have been analyzed using High Purity Germanium (HPGe) detector. The radioactivity of I-131 and Tc-99m was found 0.91 ± 0.26 BqL-1 to 504.49 ± 6.03 BqL-1 and 0.15 ± 0.21 BqL-1 to 191.19 ± 6.98 BqL-1 respectively. Radioactivity of F-18 was found from 0.031 ± 0.022 BqL-1 to 0.282 ± 0.065 BqL-1. The effective doses of occupational workers have been also calculated using the radioactivity concentration and the dose coefficient according to ICRP publication 78. Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 64−80

Development, validation, and application of a generic image-based noise addition method for simulating reduced dose computed tomography images.

Major efforts in computed tomography (CT) have been focused on reducing radiation dose to patients while maintaining adequate diagnostic quality. To that end, research tools have been developed to simulate reduced-dose images via either image-based or projection-based methods. The former is limited to fully capturing realistic texture, streak, and non-stationary characteristics of reduced dose, while the latter is impractical clinically. To develop and validate an image-based noise addition method that accounts for such attributes while being practical in clinical settings. A noise addition method was developed to add realistic noise in the image domain. The method first estimates the noise power spectrum (NPS) of CT images, which are also forward-projected to form synthetic projections. The projection data are supplemented with random white noise proportional to their attenuation values. The noise sinogram is then back-projected onto the image, filtered by the NPS, and scaled according to the desired dose reduction level. The tool was evaluated using both phantom images and patient data. The phantom images were acquired using a multi-sized image quality phantom (Mercury Phantom 3.0, Duke University), and a thorax anthropomorphic phantom (Lungman Phantom, Kyoto Kagaku) at different dose levels and reconstruction settings. The patient images consisted of two dose levels of various CT examinations and reconstruction settings. The simulated and real reduced-dose images were compared in terms of the noise magnitude and texture (i.e., NPS average frequency, NPS-fav). The utility of this methodology was also assessed for routine clinical use for CT protocol review. For the phantom images, the percent errors in the noise magnitude between the simulated images and the actual images of the Mercury Phantom and anthropomorphic phantom images were 3.34% and 3.50%, respectively. The difference in fav was 0.07mm-1 for the Mercury Phantom and 0.06mm-1 for the anthropomorphic phantom between the simulated and actual images. The average noise magnitude percent error between the simulated and actual patient images was 4.61% with noise texture judged to be visually comparable with some kernel dependencies. When implemented clinically, the tool proved practical to simplify the process of estimating radiation dose reduction for CT protocols, resulting in a 50% dose reduction of our multiple myeloma protocol. The method generated simulated CT images with realistic noise properties similar to images acquired at the same radiation exposure without needing access to raw projection data.

Internal radiation dose estimates in organs of Wistar rats exposed to sprayed neutron-activated 31SiO2 microparticles: first results of international multicenter study.

Neutron-activated 31Si is an almost pure beta emitter and is one of the short-lived radionuclides, including beta-gamma emitter 56Mn, which were created in a form of residual radioactivity in the early period after the atomic bombing of Hiroshima and Nagasaki. The features of the biological effects of internal irradiation by these radionuclides are a subject of scientific discussions and research. The publication presents data on internal radiation doses in experimental Wistar rats that were exposed to sprayed neutron-activated microparticles of 31SiO2. Doses of internal radiation could be conditionally divided into three groups according to their values. It has been found that elevated values of internal radiation doses in rats' organs/tissues as a result of exposure to sprayed 31SiO2 microparticles with initial activity of 3.2 × 107Bq varied from 10 to 120mGy (eyes, lungs, skin, stomach, jejunum, large intestine). The moderate dose values were in the range from 1.9 to 3.7mGy (trachea, esophagus, ileum). The smallest doses were received by the kidney, testis, blood, cerebellum, heart, liver, cerebrum, bladder, spleen and thymus (from 0.11 to 0.94mGy). The obtained data are important for interpreting the results of ongoing and planned biological experiments with 31SiO2 microparticles-in comparison with the previously published data on features of biological effects caused by beta-gamma emitting 56MnO2 neutron-activated microparticles.

Introduction and evaluation of size-specific DLP for radiation dose estimation in CT examinations.

The increased utilization of computed tomography (CT) has raised concerns about patient radiation exposure. Effective dose (ED), which requires precise estimation, is crucial for assessing and managing these risks. Traditional ED estimation methods, which are based on the dose-length product (DLP), often lack accuracy due to variations in patient size and anatomy. This study aims to evaluate the efficacy of size-specific DLP (SS-DLP), a novel metric that combines the size-specific dose estimate (SSDE) with scan length, to provide a more accurate estimation of radiation exposure from CT examinations. Focusing on adult chest-abdomen-pelvis (CAP) scans, we calculated SSDE and SS-DLP and utilized two simulation tools, Radimetrics and WAZA-ARI, for a detailed analysis. Our findings indicate that SS-DLP is highly correlated with EDs from Monte Carlo simulations, suggesting its reliability. Additionally, SS-DLP showed a moderate reduction in errors based on patient sex and body mass index compared to traditional DLP-based methods. Thus, SS-DLP offers a more accurate and personalized radiation exposure estimate, potentially enhancing patient safety.

Dose Reconstruction for Epidemiological Studies among Ukrainian Chernobyl Cleanup Workers.

The present paper provides an overview of the methods and summarizes the results of estimating radiation doses and their uncertainties for Ukrainian-American epidemiological studies among the Chernobyl (Chornobyl) cleanup workers. After the Chernobyl accident occurred on April 26, 1986, more than 300,000 Ukrainian cleanup workers took part between 1986 and 1990 in decontamination and recovery activities at the site of the Chernobyl Nuclear Power Plant. The U.S. National Cancer Institute in collaboration with the Ukrainian National Research Center for Radiation Medicine conducted several epidemiological studies in this population. An important part of these studies was the reconstruction of the study participants' radiation doses and the assessment of uncertainties in doses. A method called realistic analytical dose reconstruction with uncertainty estimation (RADRUE) was used to calculate the doses from external irradiation during cleanup missions, which was the main exposure pathway for most study participants. At the initial phase of the accident during the atmospheric releases of radioactivity from the destroyed reactor, the cleanup workers also received doses from inhalation of radionuclides. In addition, study participants received doses at their places of residence, especially those who lived in highly contaminated areas. The radiation doses estimated for 2,048 male cleanup workers included in the Ukrainian-American epidemiological studies varied widely: (i) bone-marrow doses from external irradiation in the case-control study of leukemia of 1,000 cleanup workers ranged from 3.7 × 10-5 mGy to 3.3 Gy (mean = 92 mGy); (ii) thyroid doses in the case-control study of thyroid cancer in 607 persons from all exposure pathways combined were from 0.15 mGy to 9.0 Gy (mean = 199 mGy); (iii) gonadal doses in 183 cleanup workers from all exposure pathways combined in the study of germline mutations in the offspring after parental irradiation (trio study) ranged from 0.58 mGy to 4.1 Gy (mean = 392 mGy); (iv) thyroid doses in the human factor uncertainties study among 47 persons were from 20 mGy to 2.1 Gy (mean = 295 mGy); and (v) lung doses in the study of germline genetic variants associated with host susceptibility to COVID-19 estimated for 211 cleanup workers were from 0.024 mGy to 2.5 Gy (mean = 249 mGy). Doses of female cleanup workers were much lower than those of male cleanup workers: the mean doses for female cleanup workers were 27 mGy for 34 women included in the trio study and 56 mGy for 48 women participated in the study of germline genetic variants associated with host susceptibility to COVID-19. Uncertainties in dose estimates included two components: (i) inherent uncertainties arising from the stochastic random variability of the parameters used in exposure assessment and from a lack of knowledge about the true values of the parameters; and (ii) human factor uncertainties due to poor memory recall resulting in incomplete, inaccurate, or missing responses during personal interviews with cleanup workers conducted long after exposure. This paper also discusses possible developments and improvements in the methods to assess the radiation doses and associated uncertainties for cleanup workers.

Is clinical target volume necessary for locally advanced non-small cell lung cancer treated with 4D-CT intensity-modulated radiation therapy

BackgroundA dosimetric evaluation is still lacking in terms of clinical target volume (CTV) omission in stage III patients treated with 4D-CT Intensity-Modulated Radiation Therapy (IMRT).Methods49 stage III NSCLC patients received 4D-CT IMRT were reviewed. Target volumes and organs at risk (OARs) were re-delineated. Four IMRT plans were conducted retrospectively to deliver different prescribed dose (74 Gy–60 Gy), and with or without CTV implementation. Dose and volume histogram (DVH) parameters were collected and compared.ResultsIn the PTV-g 60 Gy plan (PTV-g refers to the PTV generated from the internal gross tumor volume), only 5 of 49 patients had the isodose ≥ 50 Gy line covering at least 95% of the PTV-c (PTV-c refers to the PTV generated from the internal CTV) volume. When the prescribed dose was elevated to 74 Gy to the PTV-g, 33 of 49 patients could have the isodose ≥ 50 Gy line covering at least 95% of the PTV-c volume. In terms of OARs protection, the SIB-IMRT plan showed the lowest value of V5, V20, and mean dose of lung, had the lowest V55 of esophagus, and the lowest estimated radiation doses to immune cells (EDIC). The V20, V30, and mean dose of heart was lower in the simultaneous integrated boost (SIB) IMRT (SIB-IMRT) plan than that of the PTV-c 60 Gy plan.ConclusionsCTV omission was not suitable for stage III patients when the prescribed dose to PTV-g was 60 Gy in the era of 4D-CT IMRT. CTV omission plus high dose to PTV-g (74 Gy for example) warranted further exploration. The SIB-IMRT plan had the best protection to normal tissue including lymphocytes, and might be the optimal choice.

Conquering the common bile duct: outcomes in minimally invasive transcystic common bile duct exploration versus ERCP.

Given the increasing interest for surgeons to reclaim the common bile duct in managing choledocholithiasis, there is a growing movement to perform common bile duct exploration (CBDE). Advantages of concomitant CBDE with cholecystectomy include fewer anesthetic events and decreased length of stay. As there is a paucity of literature evaluating the use of the robotic platform for CBDE, our study aims to compare intraoperative and post-operative outcomes between robotic-assisted one-stage and two-stage management of choledocholithiasis. A retrospective chart review was performed from May 1, 2022 to December 31, 2023, identifying patients with choledocholithiasis who underwent robot-assisted laparoscopic cholecystectomy and transcystic CBDE with choledochoscopy (one-stage management). Preoperative, intraoperative, and post-operative variables were compared to a control group of subjects with choledocholithiasis who underwent laparoscopic cholecystectomy with pre- or post-operative ERCP (two-stage management). Statistical analysis was performed using Chi-squared, Fisher's exact, Student's T, or Mann-Whitney test. Fifty-three subjects who underwent one-stage management and 101 subjects who underwent two-stage management met inclusion criteria. Groups had similar demographics and medical history. Time to CBD clearance (45.2h vs 47.0h, p = .036), total length of stay (3.9days vs 5.1days, p = .007), fluoroscopy time (70.3s vs 151.4s, p < .001), and estimated radiation dose (23.0mSv vs 40.3mSv, p = .002) were significantly lower in the one-stage group compared to two-stage. Clearance rates, complication rates, and 30-day readmission rates were similar for both groups. Total length of stay and radiation exposure remained significantly lower on subanalysis comparing one-stage management to two-stage management with ERCP either before or after cholecystectomy. Robotic-assisted laparoscopic cholecystectomy with transcystic common bile duct exploration via choledochoscopy is a safe and feasible option in the management of choledocholithiasis. It offers a shorter time to duct clearance, shorter length of stay, and less radiation exposure when compared to two-stage management.

Development of a Real-Time Radiation Exposure Estimation Method Using a Depth Camera for Radiation Protection Education

X-ray fluoroscopy causes relatively high radiation exposure to physicians, radiation professionals, and patients. Understanding the behavior of scattered radiation is crucial for reducing occupational exposure. We developed a system for estimating radiation exposure during fluoroscopy by monitoring the position of the physician using a depth camera for radiation protection education. The dose distribution of scattered radiation in an X-ray room was simulated using Monte Carlo code. The data were displayed using augmented reality markers, and the dose at each joint point location was estimated using body tracking. Additional functions were created, such as displaying arbitrary two-dimensional cross-sections. The system performance ranged from 9.0 to 11.0 FPS with or without motion and a protective apron. The estimated doses were 0.93 to 1.21 times the measured doses for all joint points, except for the chest and pelvis. The estimated doses for the chest and pelvis were lower than the measured dose, with the minimum values being 0.72 and 0.60 times lower for the chest and pelvis, respectively. The system provides valuable insight into the estimation of radiation dose at joint points based on the physician’s position and movements, the physician’s optimal fluoroscopy location, and warning of dangerous exposure doses.

Evaluating the Utility of Iron Oxide Nanoparticles for Pre-Clinical Radiation Dose Estimation

Evaluating the Utility of Iron Oxide Nanoparticles for Pre-Clinical Radiation Dose Estimation

Estimation of Radiation Dose to the Eye Lens in Cranial Computed Tomography Examinations in Federal Neuro-Psychiatric Hospital Maiduguri, Borno State, Nigeria

Estimation of Radiation Dose to the Eye Lens in Cranial Computed Tomography Examinations in Federal Neuro-Psychiatric Hospital Maiduguri, Borno State, Nigeria

Initial Results of Low Earth Orbit Space Radiation Dosimeter on Board the Next Generation Small Satellite-2

As human exploration goals shift from missions in low Earth orbit (LEO) to long-duration interplanetary missions, radiation protection remains one of the key technological issues that must be resolved. The low Earth orbit space radiation dosimeter (LEO-DOS) instrument to measure radiation levels and create a global dose map in the LEO on board the the next generation small satellite-2 (NEXTSat-2) was launched successfully on May 25, 2023 using the Nuri KSLV-III in Korea. The NEXTSat-2 orbits the Earth every 100 minutes, in an orbit with an inclination of 97.8° and an altitude of about 550 km above sea level. The LEO-DOS is equipped with a particle dosimeter (PD) and a neutron spectrometer (NS), which enable the measurement of dosimetric quantities such as absorbed dose (D), dose equivalent (H) for charged particles and neutrons. To verify the observations of LEO-DOS, we conducted a radiation dose estimation study based on the initial results of LEO-DOS, measured from June 2023 to September 2023. The study considered four source categories: (i) galactic cosmic ray particles; (ii) the South Atlantic Anomaly region of the inner radiation belt (IRB); (iii) relativistic electrons and/or bremsstrahlung in the outer radiation belt (ORB); and (iv) solar energetic particle (SEP) events.

Sex differences in constructing dose-response calibration curves for micronuclei using cytokinesis-blocked micronucleus assay for radiation biological dosimetry in the Iranian population

Biological dosimetry, using chromosome damage biomarkers, can be considered as a key measure for radiation overexposure assessment. Therefore, for accurate dose estimation through biodosimetry, it's imperative for each biological dosimetry laboratory to establish its own specific dose-response calibration curve. In this research, the cytokinesis-blocked micronucleus (CBMN) assay was utilized to determine the frequencies of micronuclei (MN) per binucleated cell in human peripheral blood lymphocytes exposed to x-ray radiation using a LINAC (6 MV) at doses up to 4 Gy. The aim was to establish an in vitro dose-response calibration curve in our laboratory for the Iranian demographic by analyzing blood samples of ten participants (5 males and 5 females) through CABAS and Dose Estimate software. Our findings indicate an over-dispersion of the Poisson distribution in the pooled data across both sexes, coupled with a linear-quadratic increase in MN yield with dose which was particularly pronounced in the female group. The constructed dose-response curves for micronuclei yield are represented by equations Y= (0.0102 ± 0.0016) +(0.0296 ± 0.0054) D+(0.0232 ± 0.0017) D2 and Y= (0.0084 ± 0.0010) +(0.0212 ± 0.0034) D+(0.0160 ± 0.0011) D2 for the female groups, respectively. The alpha and beta coefficients, derived from the Dose Estimate software for each male and female group, were closely comparable with those obtained from the CABAS program and previous studies. The analysis of statistical parameters such as the Weighted Chi Squared (χ2) and p-value suggests that using distinct curves for each sex, rather than a unified biodosimetry formula for pooled data, ensures more accurate radiation dose estimates. Consequently, the findings of this study provide us with the assurance to utilize the derived calibration curve of MN for upcoming biological dosimetry needs in Iran. However, to enhance the reliability of results, it's essential to use biodosimetry with diverse assays and consider all clinical and physical parameters, given the limitations of cytogenetic assays.

Quantitative and qualitative performance evaluation of commercial metal artifact reduction methods: Dosimetric effects on the treatment planning

The presence of metal implants within CT imaging causes severe attenuation of the X-ray beam. Due to the incomplete information recorded by CT detectors, artifacts in the form of streaks and dark bands would appear in the resulting CT images. The metal-induced artifacts would firstly affect the quantitative accuracy of CT imaging, and consequently, the radiation treatment planning and dose estimation in radiation therapy. To address this issue, CT scanner vendors have implemented metal artifact reduction (MAR) algorithms to avoid such artifacts and enhance the overall quality of CT images. The orthopedic-MAR (OMAR) and normalized MAR (NMAR) algorithms are the most well-known metal artifact reduction (MAR) algorithms, used worldwide. These algorithms have been implemented on Philips and Siemens scanners, respectively. In this study, we set out to quantitatively and qualitatively evaluate the effectiveness of these two MAR algorithms and their impact on accurate radiation treatment planning and CT-based dosimetry. The quantitative metrics measured on the simulated metal artifact dataset demonstrated superior performance of the OMAR technique over the NMAR one in metal artifact reduction. The analysis of radiation treatment planning using the OMAR and NMAR techniques in the corrected CT images showed that the OMAR technique reduced the toxicity of healthy tissues by 10% compared to the uncorrected CT images.

A machine learning-based pipeline for multi-organ/tissue patient-specific radiation dosimetry in CT.

To develop a machine learning-based pipeline for multi-organ/tissue personalized radiation dosimetry in CT. For the study, 95 chest CT scans and 85 abdominal CT scans were collected retrospectively. For each CT scan, a personalized Monte Carlo (MC) simulation was carried out. The produced 3D dose distributions and the respective CT examinations were utilized for the development of organ/tissue-specific dose prediction deep neural networks (DNNs). A pipeline that integrates a robust open-source organ segmentation tool with the dose prediction DNNs was developed for the automatic estimation of radiation doses for 30 organs/tissues including sub-volumes of the heart and lungs. The accuracy and time efficiency of the presented methodology was assessed. Statistical analysis (t-tests) was conducted to determine if the differences between the ground truth organ/tissue radiation dose estimates and the respective dose predictions were significant. The lowest median percentage differences between MC-derived organ/tissue doses and DNN dose predictions were observed for the lung vessels (4.3%), small bowel (4.7%), pulmonary artery (4.7%), and colon (5.2%), while the highest differences were observed for the right lung's upper lobe (13.3%), spleen (13.1%), pancreas (12.1%), and stomach (11.6%). Statistical analysis showed that the differences were not significant (p-value > 0.18). Furthermore, the mean inference time, regarding the validation cohort, of the developed methodology was 77.0 ± 11.0 s. The proposed workflow enables fast and accurate organ/tissue radiation dose estimations. The developed algorithms and dose prediction DNNs are publicly available ( https://github.com/eltzanis/multi-structure-CT-dosimetry ). The accuracy and time efficiency of the developed pipeline compose a useful tool for personalized dosimetry in CT. By adopting the proposed workflow, institutions can utilize an automated pipeline for patient-specific dosimetry in CT. Personalized dosimetry is ideal, but is time-consuming. The proposed pipeline composes a tool for facilitating patient-specific CT dosimetry in routine clinical practice. The developed workflow integrates a robust open-source segmentation tool with organ/tissue-specific dose prediction neural networks.

Variations in head tilt during the acquisition of CBCT scans and their effects on effective radiation dose.

This study evaluated the impact of variations in anteroposterior and lateral tilts of patients' head on radiation-weighted doses to organs/tissues and effective doses using three different cone beam computed tomography machines. An anthropomorphic phantom was used to estimate radiation doses in three CBCT machines (OP300, Eagle X 3D, and Eagle Edge). Thermoluminescent dosimeters were placed in regions corresponding to pre-stablished organ/tissues. CBCT examinations from the posterior mandible and anterior maxilla regions were acquired, with three different anteroposterior angulations (0°, 30°, and 45°), and from the posterior mandible in three different lateral angulations (0°, 20° to the left, and 20° to the right side). Radiation-weighted doses for each organ/tissue and effective doses were calculated for each machine and angulation. For the posterior mandible acquisitions, anteroposterior angulations of the head at 30° and 45° yielded a reduction in effective doses in all three devices. A 20° tilt to the right side resulted in lower doses than to the left (same side as the FOV). For the anterior maxilla, increased anteroposterior angulation was associated with reduction in effective dose in two devices. Effective doses are lower when small FOV CBCT exams of the posterior mandible and anterior maxilla are acquired with increased anteroposterior head angulation at 30° and 45°. For FOV in the posterior mandible, a 20° lateral tilt towards the side opposite to the FOV also yields lower effective doses. The main contribution to these dose reductions is the decrease in dose to salivary glands.

Effective dose assessment due to inhalation of 222Rn, 220Rn, and their progeny: highlighting the major contribution of thoron in a thoron-prone area in Cameroon.

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 123Bqm-3 with a geometric mean (GM) of 62Bqm-3, and indoor thoron concentrations ranging from 36 to 688Bqm-3 with a GM of 242Bqm-3. The Equilibrium Equivalent Radon Concentration (EERC) ranged from 3 to 86Bqm-3 with a GM of 25Bqm-3, while the Equilibrium Equivalent Thoron Concentration (EETC) ranged from 1.2 to 12.5Bqm-3 with a GM of 7.6Bqm-3. Notably, all dwellings recorded radon concentrations below 100Bqm-3. 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.

Comparative analysis of the yields of dicentrics and chromosomal translocations

Purpose Chromosomal dicentrics and translocations are commonly employed as biomarkers to estimate radiation doses. The main goal of this article is to perform a comparative analysis of yields of both types of aberrations. The objective is to determine if there are relevant distinctions between both yields, allowing for a comprehensive assessment of their respective suitability and accuracy in the estimation of radiation doses. Materials and methods The analysis involved data from a partial-radiation simulation study with the calibration data obtained through two scoring methods: conventional and PAINT modified. Subsequently, a Bayesian bivariate zero-inflated Poisson model was employed to compare the posterior marginal density of the mean of dicentrics and translocations and assess the differences between them. Results When employing the conventional method of scoring, the findings indicate that there is no notable disparity between the yield of observed translocations and dicentrics. However, when utilizing the PAINT modified method, a notable discrepancy is observed for higher doses, indicating a relevant difference in the mean number of the two types of aberrations. Conclusions The choice of scoring method significantly influences the analysis of radiation-induced aberrations, especially when distinguishing between complex and simple chromosomal formations. Further research and analysis are necessary to gain a deeper understanding of the factors and mechanisms impacting the formation of dicentrics and translocations.

Molecular mechanisms of neutron radiation dose effects on M1 generation peas

The dose effect of radiation has long been a topic of concern, but the molecular mechanism behind it is still unclear. In this study, dried pea seeds were irradiated with 252Cf fission neutron source. Through analyzing the transcriptome and proteome of M1 generation pea (Pisum sativum L.) leaves, we studied the molecular rule and mechanism of neutron dose effect. Our results showed three important rules of global gene expression in the studied dose range. The rule closely related to the neutron absorbed dose at the transcription and translation levels is: the greater the difference in neutron absorbed dose between two radiation treatment groups, the greater the difference in differential expression between the two groups and the control group. We also obtained important sensitive metabolic pathways of neutron radiation, as well as related key genes. Furthermore, the overall molecular regulation mechanism of dose effect was revealed based on the main functional items obtained. Our research results can be applied to appropriate radiation dose estimation and agricultural production practice.

Enhanced internal dosimetry for alimentary tract organs in nuclear medicine based on the ICRP mesh-type reference phantoms

This study introduces a refined approach for more accurately estimating radiation doses to alimentary tract organs in nuclear medicine, by utilizing the ICRP pediatric and adult mesh-type reference computational phantoms (MRCPs) that improved the anatomical representation of these organs. Our initial step involved compiling a comprehensive dataset of electron Specific Absorbed Fractions (SAFs) for all source-target pairs of alimentary tract organs in both adult and pediatric phantoms, calculating SAFs for all cases in the present study only except those computed in the previous study for certain pediatric phantom cases. Subsequently, we determined S values for 1252 radionuclides, facilitating dosimetry applications. The consistency of target and source masses for alimentary tract organs in the MRCPs with the reference values in ICRP Publication 89 led to noticeable differences in SAF, S values, and consequently, absorbed dose coefficients when compared to the stylized models in ICRP Publication 100. Notably, the S value ratios (MRCP/stylized) for selected radionuclides—11C, 18F, 68Ga, and 131I—ranged from 0.41 to 7.60. Particularly for therapeutic 131I-iodide in thyroid cancer, the use of MRCPs resulted in up to 1.49 times higher absorbed dose coefficients for the colon than those derived from stylized models, while the stomach dose coefficients decreased by a factor of 0.72. The application of our findings promises enhanced, more realistic dosimetry for alimentary tract organs, especially beneficial for radiopharmaceuticals likely to accumulate within these organs.