Body Dose Research Articles

Investigation on the impact of the spatial arrangement of individuals in a standing-type in-vivo monitoring system

An automated standing type Quick Scan Whole Body Monitor (QS-WBM) has been developed for the measurement of internal radioactive contamination due to high energy photon (HEP) emitters (Eϒ >200keV). Individuals are monitored while standing on a platform inside QS-WBM at specified reference position. Instances may occur where individuals deviate from their monitoring position, potentially leading to errors in the measurement of the body content. Positional inaccuracies are estimated in three potential scenarios: lateral displacement of the individual, movement perpendicular to the detector face, and forward bending of the torso. The Monte Carlo particle transport code FLUKA is used for estimation of efficiencies for selected radionuclides across various geometrical positions for adult male radiation workers. Approximately, 8% variation in calibration factors (CFs) is noted for lateral movements up to 15 cm from the centerline regardless of the energy, while perpendicular movements from reference position exhibit variations ranging from 14 to 60 %. This study helps in quantifying uncertainties in the estimation of body content and dose, arising from deviations in position of individuals in QS-WBM enclosure during monitoring.

Ethnic Differences in Response to Oral Vitamin D Supplementation: A Systematic Review and Meta-analysis.

Individual variability in oral vitamin D supplement response hinders the understanding of its clinical impact, and while ethnicity has been implicated in this variability it has not been well described. The aim was to systematically assess the impact of ethnicity on response to oral vitamin D supplementation. The Web of Science and PubMed databases were searched for articles published from 1960 to the end of 2020. All trials in adults measuring 25(OH)D3 blood levels were included. Two reviewers independently extracted the data from the eligible studies. The change in 25(OH)D3 blood levels (95% CI) and P values were extracted, and grouped according to ethnicity, then subjected to random-effects meta-analysis. The primary outcome measurement was mean serum 25(OH)D3 levels and the secondary outcome was dose-adjusted mean serum 25(OH)D3 levels, both compared with baseline. A total of 18 studies were identified, and data from 1131 participants were extracted. Body mass index (BMI) and dose were significant covariates (Pearson correlation coefficient, P = .016 and .017) and were normalized in the meta-analysis to minimize heterogeneity, but latitude was not (P = .66). Meta-analysis showed an effect of ethnicity on dose and BMI-adjusted mean serum 25(OH)D3 levels compared with baseline (P < .00001, I2 = 98%). Asian and White study participants demonstrated a statistically higher increase in dose and BMI-adjusted 25(OH)D3 blood levels (183 nmol/L [95% CI, 163-203] and 173 nmol/L [95% CI, 152-194], respectively), compared with Arab and Black study participants (37 nmol/L [95% CI, 35-39] and 99 nmol/L [95% CI, 90-108]) using repeated t tests. Sensitivity analysis demonstrated that these findings were not impacted by potential study bias or the inclusion of immigrant populations. Ethnicity had an impact on oral vitamin D response. Further prospective studies should examine if ethnicity-based dose stratification in both clinical practice and clinical trials is warranted. PROSPERO registration no. CRD42023410076.

Correlation of dynamic blood dose with clinical outcomes in radiotherapy for head-and-neck cancer

Background and purposeRadiation-induced lymphopenia (RIL) during cancer radiotherapy is receiving growing attention due to its association with adverse clinical outcomes. Correlations between RIL and poorer locoregional control (LRC), distant-metastasis-free survival (DMFS), and overall survival (OS) have been demonstrated across multiple treatment sites. Estimates of radiation delivered to circulating blood or lymphocytes have been shown to be correlated with severe RIL. This study aims to evaluate whether blood dose estimates are equally correlated with patient outcomes directly. Materials and methodsFor 298 head-and-neck cancer patients, blood dose was estimated via the total body dose (Dbody), a static blood dose model considering the mean dose to relevant organs and tissues (Dstatic), and a dynamic model which further included temporal aspects such as blood flow and treatment delivery time (Ddynamic). The latter utilized hematological dose (HEDOS), an open-source computational tool for blood dose simulations. Survival analysis was performed to evaluate potential correlations between blood dose and LRC, DMFS, and OS. ResultsMultivariable Cox regression analysis found a statistically significant (p < 0.05) correlation between various dynamic blood dose metrics and clinical outcomes. Dbody and Dstatic did not correlate with any of the outcomes considered. ConclusionA statistically significant correlation between the dynamic blood dose model and adverse clinical outcomes was observed. During multivariable regression analysis, neither static blood dose model exhibited a statistically significant correlation with any of the outcomes studied.

Ocular and the whole body radiation exposure during endoscopic retrograde cholangiopancreatography

Objective: This study aimed to analyze the average whole body radiation exposure, which changes significantly according to during endoscopic retrograde cholangiopancreatography (ERCP) difficulty and to determine whether an ocular protection device must be used by analyzing applied ocular radiation. Material and Methods: Patients &gt;18 years of age in whom an ERCP had been indicated were prospectively included in the study. Results: A total of 1173 patients were included. Increased applied radiation dose significantly correlated with increased shot rate (Rho= 0.789, p&lt; 0.001), ERCP duration (Rho= 0.487, p&lt; 0.001), cost (Rho= 0.129, p&lt; 0.001), and LOS (Rho= 0.109, p&lt; 0.001). The whole body, skin, and eye radiation exposure doses were found to be lower than the recommended limit per year (20 mSv/year). Conclusion: Limit of ocular radiation exposure during ERCP did not exceed the recommended annual limit (20 mSv/year), and it was also detected to be much lower than that. Therefore, the use of ocular visors is not recommended.

BAX and DDB2 as biomarkers for acute radiation exposure in the human blood ex vivo and non-human primate models

There are currently no available FDA-cleared biodosimetry tools for rapid and accurate assessment of absorbed radiation dose following a radiation/nuclear incident. Previously we developed a protein biomarker-based FAST-DOSE bioassay system for biodosimetry. The aim of this study was to integrate an ELISA platform with two high-performing FAST-DOSE biomarkers, BAX and DDB2, and to construct machine learning models that employ a multiparametric biomarker strategy for enhancing the accuracy of exposure classification and radiation dose prediction. The bioassay showed 97.92% and 96% accuracy in classifying samples in human and non-human primate (NHP) blood samples exposed ex vivo to 0–5 Gy X-rays, respectively up to 48 h after exposure, and an adequate correlation between reconstructed and actual dose in the human samples (R2 = 0.79, RMSE = 0.80 Gy, and MAE = 0.63 Gy) and NHP (R2 = 0.80, RMSE = 0.78 Gy, and MAE = 0.61 Gy). Biomarker measurements in vivo from four NHPs exposed to a single 2.5 Gy total body dose showed a persistent upregulation in blood samples collected on days 2 and 5 after irradiation. The data indicates that using a combined approach of targeted proteins can increase bioassay sensitivity and provide a more accurate dose prediction.

Clinical Factors Influencing the Radiation Dose of Circulating Immune Cells during Radiotherapy for Small Cell Lung Cancer.

Small cell lung cancer (SCLC) has garnered significant attention due to its high malignancy, propensity for distant metastasis, and poor prognosis. Radiotherapy remains the cornerstone of treatment for limited-stage small cell lung cancer (LS-SCLC). However, outcomes with radiotherapy alone or in combination with chemotherapy remain suboptimal. Radiotherapy can induce lymphopenia by directly irradiating hematopoietic organs or destroying mature circulating lymphocytes, leading to immunosuppression and consequently diminishing therapeutic efficacy. The estimated dose of radiation to immune cells (EDRIC) model integrates factors such as hemodynamics, lymphocyte radiosensitivity, and proliferation capacity. This study employs the EDRIC model with enhancements to calculate the circulating immune cell radiation dose. By utilizing the EDRIC methodology, the study explores the correlation between EDRIC and tumor target size, average lung dose, average heart dose, clinical features, and peripheral blood lymphocytopenia during radiotherapy for LS-SCLC, aiming to inform personalized patient treatment strategies. This study analyzed data from 64 LS-SCLC patients who met the inclusion criteria at the General Hospital of Ningxia Medical University from January 2023 to January 2024, all of whom received radical thoracic conventional fractionated radiotherapy. Lymphocyte counts were recorded at the following points: before radiotherapy, at the lowest observed value during radiotherapy, at the end of radiotherapy, and one-month post-radiotherapy. Dosimetric data, including average lung, heart, and body doses, were extracted from the treatment planning system, and the circulating EDRIC was calculated using this model. The relationship between EDRIC values and therapeutic outcomes was analyzed. In LS-SCLC, the EDRIC model effectively predicts lymphocyte count reduction, correlating with planning target volume (PTV; cm3), TNM stage, and the percentage of target lesion shrinkage. Post-radiotherapy, there was a significant decrease in peripheral blood lymphocyte counts, with greater EDRIC values indicating more pronounced lymphocyte reduction.

A model study on the effect of human's height variability in particle deposition and retained dose in the respiratory tract.

The objective of the current study was to investigate the impact of human's height variability to the deposition percentage, the deposited and the retained dose of particulate matter in the respiratory tract. In addition, the dose to the oesophagus, blood and lymph nodes was evaluated after particle clearance. A methodology which correlates anatomical and physiological parameters with height was adopted into an existing particle dosimetry model (Exposure Dose Model 2, ExDoM2). Model results showed that deposition of particles with aerodynamic diameter (dae) ranging from 0.001 to 10 μm depends on the competition between anatomical/physiological parameters, with the maximum effect induced from height variability to be observed for particles in the size range of 0.30 μm <dae <1.5 μm. Specifically, a decrease in the subject's height by 100 cm (from 175 to 75 cm) caused a 60.5 ± 6.8% increase in the total deposition percentage during light exercise. Contrarily, an increase in the subject's height by 100 cm (from 75 to 175 cm) caused a 376% increase in the daily deposited dose of PM10 in the respiratory tract. Investigating the inter-subject variability of PM10 dose showed that the extrathoracic region was characterized by lower variability (10.0%) compared to the thoracic region (16.2%). After clearance, the highest variability was observed for blood (15.7%), followed by the respiratory tract (12.1%), lymph nodes (10.4%) and oesophagus (10.1%). Results of the current study highlight the impact induced by incorporating height to scale the inter-subject variability in particle deposition and dose in the human body.

Stereotactic body radiation therapy for prostate cancer: a dosimetric comparison of IMRT and VMAT using flattening filter and flattening filter-free beams.

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 36.25Gy 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.

A feasibility study of dosimetry for breast cancer radiotherapy based on body surface changes.

The requirement for precise and effective delivery of the actual dose to the patient grows along with the complexity of breast cancer radiotherapy. Dosimetry during treatment has become a crucial component of guaranteeing the efficacy and security. To propose a dosimetry method during breast cancer radiotherapy based on body surface changes. A total of 29 left breast cancer radiotherapy cases were retroactively retrieved from an earlier database for analysis. Non-rigid image registration and dose recalculation of the planning computed tomography (CT) referring to the Cone-beam computed tomography were performed to obtain dose changes. The study used 3D point cloud feature extraction to characterize body surface changes. Based on the correlation proof, a mapping model is developed between body surface changes and dose changes using neural network framework. The MSE metrics, the Euclidean distances of feature points and the 3D gamma pass rate metric were used to assess the prediction accuracy. A strong correlation exist between body surface changes and dose changes (first canonical correlation coefficient=0.950). For the dose deformation field and dose amplitude difference in the test set, the MSE of the predicted and actual values were 0.136 pixels and 0.229 cGy, respectively. After deforming the planning dose into a deformed one, the feature points' Euclidean distance between it and the recalculated dose changes from 9.267±1.879mm to 0.456±0.374mm. The 3D gamma pass rate of 90% or higher for the 2mm/2% criteria were achieved by 80.8% of all cases, with a minimum pass rate of 75.9% and a maximum pass rate of 99.6%. Pass rate for the 3mm/2% criteria ranged from 87.8% to 99.8%, with 92.3% of the cases having a pass rate of 90% or higher. This study provides a dosimetry method that is non-invasive, real-time, and requires no additional dose for breast cancer radiotherapy.

Adaptive radiotherapy for muscle invasive bladder cancer: a retrospective audit of two bladder filling protocols

BackgroundRadical radiotherapy for muscle-invasive bladder cancer (MIBC) is challenging due to large variations in bladder shape, size and volume during treatment, with drinking protocols often employed to mitigate geometric uncertainties. Utilising adaptive radiotherapy together with CBCT imaging to select a treatment plan that best fits the bladder target and reduce normal tissue irradiation is an attractive option to compensate for anatomical changes. The aim of this retrospective study was to compare a bladder empty (BE) protocol to a bladder filling (BF) protocol with regards to variations in target volumes, plan of the day (PoD) selection and plan dosimetry throughout treatment.MethodsForty patients were included in the study; twenty were treated with a BE protocol and twenty with a BF protocol to a total prescribed dose of 55 Gy in 20 fractions. Small, medium and large bladder plans were generated using three different CTV to PTV margins. Bladder (CTV) volumes were delineated on planning CTs and online pre-treatment CBCTs. Differences in CTV volumes throughout treatment, plan selection, PTV volumes and resulting dose metrics were compared for both protocols.ResultsMean bladder volume differed significantly on both the planning CTs and online pre-treatment CBCTs between the protocols (p < 0.05). Significant differences in bladder volumes were observed between the planning CT and pre-treatment CBCTs for BF (p < 0.05) but not for BE (p = 0.11). Both protocols saw a significant decrease in bladder volume between first and final treatment fractions (p < 0.05). Medium plans were preferentially selected for BE whilst when using the BF protocol the small plan was chosen most frequently. With no significant change to PTV coverage between the protocols, the volume of body receiving 25.0–45.8 Gy was found to be significantly smaller for BE patients (p < 0.05).ConclusionsThis work provides evidence in favour of a BE protocol compared to a BF protocol for radical radiotherapy for MIBC. The smaller treatment volumes observed in the BE protocol led to reduced OAR and total body doses and were also observed to be more consistent throughout the treatment course. These results highlight improvements in dosimetry for patients who undergo a BE protocol for MIBC.

G0-PCC-FISH derived multi-parametric biodosimetry methodology for accidental high dose and partial body exposures

High dose radiation exposures are rare. However, medical management of such incidents is crucial due to mortality and tissue injury risks. Rapid radiation biodosimetry of high dose accidental exposures is highly challenging, considering that they usually involve non uniform fields leading to partial body exposures. The gold standard, dicentric assay and other conventional methods have limited application in such scenarios. As an alternative, we propose Premature Chromosome Condensation combined with Fluorescent In-situ Hybridization (G0-PCC-FISH) as a promising tool for partial body exposure biodosimetry. In the present study, partial body exposures were simulated ex-vivo by mixing of uniformly exposed blood with unexposed blood in varying proportions. After G0-PCC-FISH, Dolphin’s approach with background correction was used to provide partial body exposure dose estimates and these were compared with those obtained from conventional dicentric assay and G0-PCC-Fragment assay (conventional G0-PCC). Dispersion analysis of aberrations from partial body exposures was carried out and compared with that of whole-body exposures. The latter was inferred from a multi-donor, wide dose range calibration curve, a-priori established for whole-body exposures. With the dispersion analysis, novel multi-parametric methodology for discerning the partial body exposure from whole body exposure and accurate dose estimation has been formulated and elucidated with the help of an example. Dose and proportion dependent reduction in sensitivity and dose estimation accuracy was observed for Dicentric assay, but not in the two PCC methods. G0-PCC-FISH was found to be most accurate for the dose estimation. G0-PCC-FISH has potential to overcome the shortcomings of current available methods and can provide rapid, accurate dose estimation of partial body and high dose accidental exposures. Biological dose estimation can be useful to predict progression of disease manifestation and can help in pre-planning of appropriate & timely medical intervention.

Evaluation of uncertainty in personal dose measured using CaSO4:Dy-based TLD badge at different workplaces.

The metrological quality of a measurement is characterised by evaluating the uncertainty in the measurement. In this paper, uncertainty in personal dose measured using individual monitoring CaSO4:Dy-based thermoluminescence dosimeter badge is evaluated by application of the guide to the expression of uncertainty in measurement method. The present dose reporting quantity, whole body dose (WBD) and the proposed quantity, personal dose equivalent, Hp(10) has been used as measurands. The influence of various input quantities on the measurement were analyzed through tests that conform to the requirements of the International Electrotechnical Commission IEC 62387. The study found that the expanded uncertainties for WBD and Hp(10) measurements were 63.4% and 41.4%, respectively, corresponding to a 95% coverage probability for workplace fields covering a wide photon energy range (33-1250keV). However, the uncertainty estimates were quite lower for the type of workplaces that are identified using the dose evaluation algorithm. The input quantities, namely, the response to a mixture of photon beam qualities and photon energy and angular dependence contribute the most to the total uncertainty.

Commissioning of the first hospital-based PET radiopharmaceutical cyclotron in Greece: personnel dose assessment

The role of 18F–fluoro–deoxy–glucose in positron emission tomography (PET) imaging is well established in diagnosis and management of cancer patients. Installations of on-site self-shielded mini cyclotrons are increasing. The Dose on Demand Biomarker Generator BG-75 was installed at Metaxa Cancer Hospital, Greece, in May 2021 and is the first hospital-based PET radiopharmaceutical cyclotron in the country. Personnel expected external exposure was established during commissioning; internal exposure is not expected. Personnel dose was estimated with two methods: survey meter measurements in various locations combined with the time spent in each location, and direct measurement using electronic personal dosemeters. Gamma and neutron radiation readings outside the cyclotron vault were at background levels. Inside the cyclotron vault, the highest recorded radiation readings by the target were 18 μSv h−1 for both gammas and neutrons with cyclotron in operational mode; at one meter, the values were 5 μSv h−1 and 4 μSv h−1, respectively. The annual expected whole body dose per cyclotron operator is 0.6 mSv, and the respective extremity dose 16 mSv. The annual expected whole body and extremity dose for the radiochemist is 0.3 mSv and 25 mSv, respectively. The respective annual dose estimates for the medical physicists are < 1 mSv. The expected personnel doses are well below the regulatory limits and local as low as reasonably achievable (ALARA) levels. With experience and a robust ALARA program, personnel exposure could be further reduced.

Impact of radiation dose to the immune cells in stage IV non-small cell lung cancer in the era of immunotherapy.

e20608 Background: Thoracic radiotherapy now is widely accepted in advanced lung cancer. It is not only been used as palliative therapy but also been involved in Systemic treatments in advanced lung cancer, especially in immune era. However, radiotherapy impairs immune system which can be evaluated by estimated dose of radiation to immune cells (EDRIC). Here, we sought to examine the prognostic impact of the EDRIC in advanced NSCLC in the context of immunotherapy, and to identify the factors influencing EDRIC in this population. Methods: We retrospectively enrolled patients with stage IV NSCLC who had received first-line immunotherapy and thoracic radiation therapy. EDRIC is a specific formulation using a model developed by Jin et al and improved by Ladbury et al, calculated using radiation fraction, mean lung dose (MLD), mean heart dose (MHD), and mean body dose (MBD). Spearman’s rank correlation was used to assess the correlation between variables.Associations between EDRIC [analyzed continuously and categorically (&lt;5.7Gy vs ≥5.7Gy)] and overall survival (OS) and progression-free survival (PFS) were evaluated by Kaplan-Meier and Cox proportional methods. Results: We conducted a retrospectively analysis of 152 patients with stage IV NSCLC patients. GTV (r = 0.2023, p = 0.0137), PTV (r = 0.4139, p &lt; 0.0001) and N (r = 0.1897, p = 0.0193) stage showed a positive correlation with EDRIC. Negative correlations of lymphocyte nadir with EDRIC (r = -0.3172, p &lt; 0.0001), during/pre lymphocyte nadir with EDRIC (r = -0.2102, p = 0.0093), during/post lymphocyte nadir with EDRIC (r = -0.2750, p = 0.0006) were found. Median PFS was shorter among the EDRIC ≥5.7Gy group (10.2months vs 18.6months; p &lt; 0.0001). Median OS was also shorter among the EDRIC ≥5.7Gy group (19.8 months vs 30.2months; p = 0.024). For ORR (38% vs 46%; p = 0.413) and DCR (84% vs 92%; p = 0.304), there was no statistical significance between EDRIC≥5.7Gy and EDRIC &lt; 5.7Gy. Analyzed as a continuous variable, EDRIC was the only factor associated with worse PFS (HR = 1.001, p = 0.018) and OS (HR = 1.002, p = 0.001) in multivariate analysis. Conclusions: In the era of immunotherapy, EDRIC is an independent predictor for PFS and OS in advanced NSCLC, warranting investigation into techniques to optimize radiation dose to the immune compartment.

1981: Spleen and vertebral body dose associations with lymphopenia after ablative pancreas radiotherapy

1981: Spleen and vertebral body dose associations with lymphopenia after ablative pancreas radiotherapy

Effectiveness and safety of immune response to SARS‑CoV‑2 vaccine in patients with chronic kidney disease and dialysis: A systematic review and meta‑analysis.

The coronavirus disease 2019 (COVID-19) vaccination is the most effective way to prevent COVID-19. However, for chronic kidney disease patients on long-term dialysis, there is a lack of evidence regarding the efficacy and safety of the immune response to the vaccine. The present meta-analysis explores the efficacy and safety of COVID-19 vaccine in the immune response of patients with chronic kidney disease (CKD) undergoing dialysis. PubMed, Web of Science, Science Direct, and Cochrane Library databases were systematically searched from January 1, 2020, to December 31, 2022. Data analysis was performed using REVMAN 5.1s and Stata14 software. Baseline data and endpoint events were extracted, mainly including age, sex, dialysis vintage, body mass index (BMI), vaccine type and dose, history of COVID-19 infection, seropositivity rate, antibody titer, pain at injection site, headache and other safety events. The meta-analysis included 33 trials involving 81,348 patients. The immune efficacy of patients with CKD and dialysis was 80% (95 CI, 73-87%). The seropositivity rate of individuals without COVID-19 infection was 76.48% (3,824/5,000), while the seropositivity rate of individuals with COVID-19 infection was 80.82% (1,858/2,299). The standard mean difference of antibody titers in CKD and dialysis patients with or without COVID-19 infection was 27.73 (95% CI, -19.58-75.04). A total of nine studies reported the most common adverse events: Pain at the injection site, accounting for 18% (95 CI, 6-29%), followed by fatigue and headache, accounting for 8 (95 CI, 4-13%) and 6% (95 CI, 2-9%), respectively. COVID-19 vaccine benefitted patients with CKD undergoing dialysis with seropositivity rate ≥80%. Adverse events such as fatigue, headache, and pain at the injection site may occur after COVID-19 vaccination but the incidence is low.

The RADTRAD analysis methodology for the Fuel Handling Accident during the long-term shutdown period of Chinshan Nuclear Power Plant

Abstract This study presents a methodology for the Fuel Handling Accident (FHA) analysis during the long-term shutdown period with the fuels still residing in the reactor core for the Chinshan BWR/4 Nuclear Power Plant. This methodology can be used to calculate the radiation dose received by the control room personnel, assuming failure in safety systems, facilities or structures. The computer code RADTRAD is employed to perform the transport and release of radioactive inventories first, and then calculate the control room dose based on appropriate dose conversion factor for the FHA. The results show that even failure in safety systems, facilities or structures, the whole body dose, thyroid dose and beta-skin dose are well below the acceptance limits specified in the Standard Review Plan.

Anti-radiation effect of MRN-100: a hydro-ferrate fluid, in vivo.

Ionizing radiation (IR) severely harms many organs, especially the hematopoietic tissue, mandating the development of protective nutraceuticals. MRN-100, a hydro-ferrate fluid, has been shown to protect γ-radiated fish against hematopoietic tissue damage and lethality. The current study aimed to examine MRN-100's protective effect against irradiated mice and explore the mechanisms underlying its effect. Mice received a single acute, sub-lethal, 5Gy, whole body dose of X-ray IR. MRN-100 treatment was administered daily for 2-weeks pre-irradiation until 1-week post-irradiation. Spleen and blood were analysed for oxidative stress, hematological, histological and biochemical parameters. Radiation exposure markedly decreased complete blood count (CBC) parameters including hemoglobin, hematocrit, red blood cells, platelets, white blood cells and lymphocytes, and significantly increased neutrophils. In contrast, MRN-100 supplementation to irradiated mice ameliorated all CBC parameters and protected against DNA damage in both splenic cells and serum. It also had an antioxidant effect, increasing the levels of glutathione, superoxide dismutase, catalase and total antioxidant capacity, which were otherwise decreased by irradiation. MRN-100 intake reduced the oxidative stress biomarker levels of nitric oxide, protein carbonyl, malondialdehyde, reactive oxygen species and 8-hydroxydeoxyguanosine, a marker specific to DNA damage. Furthermore, MRN-100 enhanced serum iron and reversed the radiation-induced elevations of liver enzymes. Finally, MRN-100 protected splenic tissue from irradiation as observed by histology. We conclude that MRN-100 consumption may protect against oxidative stress generated by radiation exposure, suggesting that it may be employed as an adjuvant treatment to prevent radiation's severe damage to important organs.

Estimation of Entrance Surface Radiation Dose to Thyroid and Gonads during Computed Tomography Thorax Examination

ABSTRACT Introduction: The organ’s sensitivity to radiation exposure varies depending on the cells in that organ. The thyroid and gonads have an increased radiation risk since the cells in those organs divide faster. This study aimed to estimate the radiation dose and to compare gender-related variations in entrance dose to the thyroid and gonads during computed tomography (CT) thorax examination. Materials and Methods: We used data from 43 patients prescribed thorax CT examinations. Thermoluminescent dosimeter (TLD) discs detect the scattered radiation dose to the thyroid and gonads. Four discs were used for each patient, two at the thyroid level and two at the gonad region. The exposed and a control TLD disc with the appropriate identifications are sent to Avanttec Laboratories, India, for readings. Results: The median thyroid dose for males and females was 7.55 mSv and 9.42 mSv, respectively. The median gonad dose was 0.11 mSv and 0.25 mSv for males and females, respectively. Gonad dose has a statistically significant difference between males and females (P &lt; 0.001). Karl Pearson’s correlation coefficient was used to check the relationship between body mass index (BMI) and dose length product (DLP), and it showed a correlation coefficient value of 0.611 in males and 0.715 in females, a strong positive correlation between BMI and DLP, irrespective of gender. Conclusion: The scattered entrance radiation dose to the thyroids and gonads was minimal during CT thorax when compared with the literature. However, we recommend providing better care using an optimized protocol with only the required area coverage to protect the thyroid and gonad.

Standardizing and improving dose predictions for head and neck cancers using complete sets of OAR contours.

Radiotherapy dose predictions have been trained with data from previously treated patients of similar sites and prescriptions. However, clinical datasets are often inconsistent and do not contain the same number of organ at risk (OAR) structures. The effects of missing contour data in deep learning-based dose prediction models have not been studied. The purpose of this study was to investigate the impacts of incomplete contour sets in the context of deep learning-based radiotherapy dose prediction models trained with clinical datasets and to introduce a novel data substitution method that utilizes automated contours for undefined structures. We trained Standard U-Nets and Cascade U-Nets to predict the volumetric dose distributions of patients with head and neck cancers (HNC) using three input variations to evaluate the effects of missing contours, as well as a novel data substitution method. Each architecture was trained with the original contour (OC) inputs, which included missing information, hybrid contour (HC) inputs, where automated OAR contours generated in software were substituted for missing contour data, and automated contour (AC) inputs containing only automated OAR contours. 120 HNC treatments were used for model training, 30 were used for validation and tuning, and 44 were used for evaluation and testing. Model performance and accuracy were evaluated with global whole body dose agreement, PTV coverage accuracy, and OAR dose agreement. The differences in these values between dataset variations were used to determine the effects of missing data and automated contour substitutions. Automated contours used as substitutions for missing data were found to improve dose prediction accuracy in the Standard U-Net and Cascade U-Net, with a statistically significant difference in some global metrics and/or OAR metrics. For both models, PTV coverage between input variations was unaffected by the substitution technique. Automated contours in HC and AC datasets improved mean dose accuracy for some OAR contours, including the mandible and brainstem, with a greater improvement seen with HC datasets. Global dose metrics, including mean absolute error, mean error, and percent error were different for the Standard U-Net but not for the Cascade U-Net. Automated contours used as a substitution for contour data improved prediction accuracy for some but not all dose prediction metrics. Compared to the Standard U-Net models, the Cascade U-Net achieved greater precision.