Dose Estimates Research Articles

Thyroid doses for the Chornobyl Tissue Bank: improved estimates based on revised methodology and individual residence and diet history.

Increased thyroid cancer incidence has been one of the principal adverse health effects of the Chornobyl (Chernobyl) nuclear power plant accident. Accurate dose estimation is critical for assessing the radiation dose-response relationship. Current dosimetry estimates for individuals from the Chornobyl Tissue Bank (CTB) are based only on the limited information on their places of residence at the time of the accident and/or at the time of surgery for thyroid cancer. The present study aimed to assess whether additional residential and dietary history data collected during personal interviews would substantially impact dose estimates. This paper presents an assessment of thyroid doses from 131I intake for the 197 exposed individuals from the CTB with pathologically confirmed papillary thyroid cancer. Thyroid doses, which had been calculated for these individuals in 2010, were revised in this study using the recently substantially revised 'Thyroid Dosimetry 2020 system for Ukraine' (TDU20). In addition, residence and diet history data were collected during personal interviews with individuals for whom dosimetry-related data were scarce. The arithmetic mean of thyroid doses estimated in this study was 510 mGy (previously 700 mGy), while the median was 81 mGy (previously 120 mGy). A rather wide range of thyroid doses from zero to 11.9Gy (previously up to 15.0Gy) was observed among study participants. The uncertainties in doses were characterized by the geometric standard deviation of 1,000 individual stochastic doses. As a result, the geometric standard deviation varied from 1.3 to 5.3 with an overall arithmetic mean of 2.7 and a median of 2.9. This study clearly showed that the use of individual questionnaire data in dose assessment of individuals who completed personal dosimetry interviews had a noticeable impact on the thyroid dose values: the thyroid doses changed by more than 100 mGy in 31 out of 104 (29.8% of the total) individuals, while such changes due to the use of TDU20 were observed in 18 out of 104 (17.3%) individuals. Clearly, future focused studies using samples from the CTB would benefit from personal interviews to improve dose estimates. Another lesson learned from this study is that whenever a radiation accident occurs, it is important to ask affected people by health and radiation safety authorities to keep records of their own behavior and diet, and, if possible, those of their children.

Comparison of Water-Equivalent and Effective Diameter-Based Size-Specific Dose Estimates in Computed Tomography Pulmonary Angiography: Implications for Radiation Dose Optimization

This retrospective study investigates dose estimation in computed tomography pulmonary angiography (CTPA) by analyzing 200 examinations from 96 male and 104 female patients. Two size-specific dose estimation (SSDE) methods were evaluated: one based on effective diameter (SSDEDeff) and the other on water-equivalent diameter (SSDEDw). The effective diameter (Deff) was manually measured using the lateral (LAT) and anteroposterior (AP) dimensions, while the water-equivalent diameter (Dw) was calculated from the region of interest (ROI) using mean Hounsfield Unit (HU) values and cross-sectional area. SSDE calculations were compared to the conventional CT dose metric, CTDIvol, to assess its underestimation relative to SSDEDw. The findings revealed a dose underestimation of up to 18% for CTDIvol compared to SSDEDw, particularly for patients with larger body habitus. SSDEDeff consistently overestimated the dose by 7.73% compared to SSDEDw, as Deff relied only on external dimensions while Dw considered tissue attenuation for a more individualized dose assessment. High correlations were observed between lateral diameter (dLAT) and both Deff (R2 = 0.9175) and Dw (R2 = 0.7578). However, the systematic overestimation by SSDEDeff emphasizes the importance of clearly specifying the metric used for SSDE, as differences can influence reported doses by 5-10%, affecting clinical dose monitoring and adherence to diagnostic reference levels. This study highlights the limitations of CTDIvol and SSDEDeff compared to SSDEDw, especially in regions with heterogeneous tissue. The results support the use of individualized radiation dose assessments to improve radiation safety, particularly in CTPA, which has seen increased application during the COVID-19 pandemic.

Addressing lung truncation in 99mTc-MAA SPECT/CT for 90Y microsphere radioembolization treatment planning

BackgroundPrior studies have established that macroaggregated albumin (MAA)-SPECT/CT offers more robust lung shunt fraction (LSF) and lung mean absorbed dose (LMD) estimates in 90Y radioembolization in comparison to planar imaging. However, incomplete SPECT/CT coverage of the lungs is common due to clinical workflows, complicating its potential use for LSF and LMD calculations. In this work, lung truncation in MAA-SPECT/CT was addressed via correction strategies to improve 90Y treatment planning.MethodsLung truncation was simulated in 56 cases with adequate (> 90%, mean: 98%) lung coverage in MAA-SPECT/CT by removing slices in ~ 5 mm increments from the lung apices to the diaphragm. A wide range of lung coverages from 100% to < 1% in ~ 2% increments were created. LSF and LMD were calculated with four methods. (1) 2D planar imaging standard (not truncated), truncated lung SPECT/CT data was: (2) used with no corrections (SPECTTrunc), (3) uniformly extrapolated to full lung coverage (SPECTUniform), (4) fit with an empirical model to predict lung counts at full lung coverage (SPECTFit). To determine counts for LSF, full lung volumes, those modified at the lung/liver boundary (Lungs 2-cm), and those isolated to the left lung (Left Lung) were used. The correction methods were then applied to 31 independent cases without full lung coverage (< 90%, mean: 74%). The variations in LSF and LMD estimates from each correction method were analyzed.ResultsAveraged across simulated lung coverages from 40 to 80%, percent errors relative to non-truncated data for SPECTTrunc were (mean ± σ) − 22% ± 15% for LSF and 34% ± 29% for LMD. SPECTUniform had similar errors with 29% ± 26% for both LSF and LMD. SPECTFit yielded the most accurate and precise estimates for LSF and LMD, with errors of 11% ± 20% for both. The Left Lung approach equalized LMD errors in all three correction methods, with percent errors of 3% ± 17% (SPECTTrunc), 2% ± 17% (SPECTUniform), and 4% ± 13% (SPECTFit). In the 31 cases without ground truth LSF or LMD, Left Lung produced highly comparable LMD estimates, with a mean (max) coefficient of variation across the three correction methods of 4% (20%).ConclusionLSF and LMD can be estimated for 90Y radioembolization using truncated lung coverage data in MAA-SPECT/CT. Empirical models to predict lung counts at full lung coverage produced LSF and LMD estimates with minimal bias and uncertainty. With lung/liver boundary adjustments, all SPECT/CT methods assessed in this work yielded LMD estimates comparable to ground truth, even down to 50% lung coverage.

Establishment of baseline size-specific dose estimate (SSDE) for paediatric head computed tomography (CT) examinations

BackgroundIn recent times, size-specific dose estimate (SSDE) has been the ideal metric for accurate estimation of individual patient doses in computed tomography (CT) examinations. The objective of this study was to estimate patient radiation doses based on SSDE and the water-equivalent diameter (DW) as an effect tool for dose optimization in paediatric head CT at two facilities in Tamale Metropolis, in the northern region of Ghana. This is a preliminary retrospective study conducted on 57 paediatric patients (comprising 32 males and 25 females), aged newborns to 16 years old, who underwent head CT examinations. Patient head sizes were determined in terms DW, which was calculated by manual contouring the circumference of the CT images excluding the background to measure the region of interest (ROI) using the mid-slice axial CT images. SSDE was calculated as the product of CTDIvol and the size-specific conversion coefficients (CTDIvol, 16 to SSDE) obtained from the American Association of Physicists in Medicine (AAPM) Report 293.ResultsAt facility ‘A’, the median SSDE values for patients, aged 3 months to 1 year, 1 to 6 years, and older than 6 years were 46.1 mGy, 39.6 mGy, and 48.2 mGy, respectively. The corresponding CTDIvol values were 42.3 mGy, 39.1 mGy, and 51.7 mGy. Facility ‘B’ reported median SSDE values of 36.0, 39.2, and 43.8 mGy, with corresponding CTDIvol values of 28.7, 39.8, and 46.9 mGy for the same age categories. For all age groups, the two facilities showed significant differences in SSDE values (44.72 mGy vs. 39.77 mGy, p = 0.009) and CTDIvol values (45.72 mGy vs. 40.60 mGy, p = 0.03). Some of the age group doses were up to 25.3% in CTDIvol and 25.8% in SSDE higher than those found in published data.ConclusionsThe SSDEs estimated showed significant variations between the two facilities, indicating a possible variability of scan protocols for paediatric head CT examinations. The SSDEs obtained in this study could be useful for optimization of paediatric routine head CT examinations.

Influence of statistical methods on lower limits of dose estimation in biological dosimetry

Purpose In cases of radiological or nuclear events, biological dosimetry enables decisions whether an individual was exposed to ionizing radiation and the estimation of the dose. Several statistical methods are used to assess uncertainties. The stringency of the applied method has an impact on the lowest dose that can be detected. To obtain reliable and comparable results, it is crucial to harmonize the applied statistical methods. Materials and methods The decision threshold and detection limit of the statistical methods were derived for variable cell numbers. The coverage of the 95% confidence intervals as well as the false-positive and false-negative rates of the methods were compared based on simulations. The evaluated methods included a graphical method, the propagation of errors and a Bayesian method. Results The minimum resolvable doses, the doses at the detection limit and the coverage were relatively variable between the compared methods. The Bayesian method showed the best coverage, lowest resolvable doses and had false-positive rates close to 5%. The graphical method with the combination of two 83% confidence intervals also showed promising results. The other methods were either too conservative or underestimated the uncertainties for some doses or cell numbers. Conclusions The assessment of the lower dose limits is a central part of biological dosimetry and the applied statistical methods have a strong influence on the interpretation of the results. Simulations enable comparisons between methods and provide important information for the harmonization and standardization of the uncertainty assessment.

Dose Estimation for Indoor Radon, Occupational Radiation, and Electromagnetic Field Exposure in a Nuclear Medicine Department in Turkiye.

In this study, the occupational radiation dose, radon gas, and non-ionizing radiation doses originating from electromagnetic fields (EMF) to which radiation workers are exposed were monitored and evaluated for 1 y. Using electronic personnel dosimeters (EPD), average daily radiation doses based on the number of patients and annual average effective dose results of radiation workers were obtained over a period of 1 y. Also, the annual effective dose and risk values were calculated for 8 h and 24 h by taking radon gas measurements at 2-mo intervals in the nuclear medicine department. Finally, electric field measurements were made one day a week in the selected areas. All the results obtained were compared with national and international dose limits. The results obtained as a result of EPD, radon gas, and EMF measurements made in the nuclear medicine department were found to be far below the international and national legal dose limits.

Estimation of heart dose in left breast cancer radiotherapy: Assessment of vDIBH feasibility using the supervised machine learning algorithm.

The volunteer deep inspiration breath hold (vDIBH) technique is used to reduce the heart dose in left breast cancer radiotherapy. Many times, it is faced that despite rigorous exercise and training, not all patients get benefited as expected. The primary objective of this study was to develop a machine learning program for prediction of mean heart dose before left breast radiotherapy under vDIBH. The present work is based on the dosimetric parameters of eighty-two left breast cancer patients, who have undergone modified radical mastectomy, enrolled for their radiation treatment. The trained machine learning algorithm employed linear regression to establish a correlation between Haller Index and heart mean dose (HMD) received during the ca left breast cancer radiotherapy. Subsequently, HMD values were used to model the regression relationship with maximum heart distance (MHD). The method adopted is beneficial in patient selection and assessment for suitability of patients' radiotherapy planning under vDIBH treatment technique. For data from 21 test patients, the mean of HMD obtained from the treatment planning system (TPS) and the mean of predicted HMD by developed program were found to be 468.76 cGy and 464.66 cGy, respectively. The present work facilitates precise HMD prediction in left breast cancer radiation therapy even before starting the treatment planning process. Additionally, this program offers suggestions in terms of modifications in treatment settings for even better results of vDIBH techniques if not matches with the anticipated results.

The Effect of Air Exchange Rate and Room Size on Dose Estimation of Partial Substitution of Tin Slag 2 on Fine Aggregate in Making Mortar in Buildings

Tin slag 2 is a by-product of the tin processing and smelting industry. Tin slag 2 contains radioactive from the uranium and thorium decay series with specific activity concentrations. The current condition of tin slag 2 is still stored in storage. This study aims to simulate using tin slag 2 as a partial substitute for fine aggregate in making mortar, used as a floor or wall plastering material. Dose analysis of the use of mortar–tin slag 2 using RESRAD-BUILD. Several radionuclides were measured in tin slag 2, such as 226Ra 5.72 Bq/gram, 228Th 14.29 Bq/gram, 228Ra 16.59 Bq/gram, and potassium 1.16 Bq/gram. According to the regulations, the activity concentration limit is 1 Bq/gram for the uranium and thorium decay series radionuclide and 10 Bq/g for the potassium. Simulations were performed using RESRAD-BUILD software with scenarios of 2 room sizes against one assumption of the building/air exchange rate. In 2 room size assumptions, namely 4x3x2.5 m and 4x5x2.8 m, the results showed that the larger the room size, the smaller the dose received. Assuming the same building exchange rate, because the sizes used are different, the amount of air exchanged will also be different and affect the dose received by the receptor. The challenge that must be considered is that the air exchange rate is greatly influenced by various factors such as design, ventilation systems, natural or mechanical, environmental conditions, etc. Keywords: tin, slag 2, partial, substitution, mortar

Breast radiotherapy planning: A decision-making framework using deep learning.

Effective breast cancer treatment planning requires balancing tumor control while minimizing radiation exposure to healthy tissues. Choosing between intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) remains pivotal, influenced by patient anatomy and dosimetric constraints. This study aims to develop a decision-making framework utilizing deep learning to predict dose distributions, aiding in the selection of optimal treatmenttechniques. A 2D U-Net convolutional neural network (CNN) model was used to predict dose distribution maps and dose-volume histogram (DVH) metrics for breast cancer patients undergoing IMRT and 3D-CRT. The model was trained and fine-tuned using retrospective datasets from two medical centers, accounting for variations in CT systems, dosimetric protocols, and clinical practices, over 346 patients. An additional 30 consecutive patients were selected for external validation, where both 3D-CRT and IMRT plans were manually created. To show the potential of the approach, an independent medical physicist evaluated both dosimetric plans and selected the most appropriate one based on applicable clinical criteria. Confusion matrices were used to compare the decisions of the independent observer with the historical decision and the proposed decision-makingframework. Evaluation metrics, including dice similarity coefficients (DSC) and DVH analyses, demonstrated high concordance between predicted and clinical dose distribution for both IMRT and 3D-CRT techniques, especially for organs at risk (OARs). The decision-making framework demonstrated high accuracy (90 ), recall (95.7 ), and precision (91.7 ) when compared to independent clinical evaluations, while the historical decision-making had lower accuracy (50 ), recall (47.8 ), and precision (78.6 ). The proposed decision-making model accurately predicts dose distributions for both 3D-CRT and IMRT, ensuring reliable OAR dose estimation. This decision-making framework significantly outperforms historical decision-making, demonstrating higher accuracy, recall, and precision.

Evaluation of Environmental Radiation Exposure and Algorithms for Determining the Occupational Effective Dose During 99mTc-MDP Bone Scintigraphy: A Comprehensive Analysis

This study evaluated the occupational exposure of radiopharmacists, nurses, radiological technologists, and radiological technologist assistants involved in 99mTc-MDP bone scintigraphy procedures. Actual occupational effective doses for individual staff needed ascertaining. An environmental radiation exposure audit revealed all nuclear medicine areas were compliant with ICRP and IAEA guidelines. To ascertain individual doses, they were recorded by OSL badges. The highest exposure was to the radiopharmacists, Hp(0.07) 2.19 µSv during radiolabeling. The nurse administering 99mTc-MDP recorded a dose of 0.27 µSv at Hp(0.07), 26.01% of the total occupational effective dose. The radiological technologist and assistant receive 73.05% of the total effective dose. However, the highest effective dose was received by the technologist assistant positioning patients for SPECT/CT scans, with an effective dose of 32.03 µSv. Single and double dosimetry effective dose estimate algorithms were evaluated, resulting in the double dosimetry being more accurate. The Padovani et al. algorithm was found to most closely align with 99mTc-MDP actual effective dose values (p &gt; 0.05), thereby validating the measurement methods used in this study. The research offers benchmark environmental exposure and effective doses applicable in audits and the continuous effort to enhance radiation safety for personnel during 99mTc-MDP bone scintigraphy.

Trends of invitro pharmacological potency and invivo pharmacokinetics parameters of modern drugs: Can the therapeutic/subtherapeutic dose be estimated from invitro Ki and pharmacokinetic parameters?

In drug discovery and development, estimating therapeutic and subtherapeutic doses is crucial for designing early-phase clinical trials, particularly first-in-human (FIH) studies. While increasing the invitro pharmacological potency (lowering Ki) of a compound to its target is expected to decrease the therapeutic dose, its benefit is not necessarily clarified. We analyzed invitro Ki, human invivo pharmacokinetics (PK) parameters, and therapeutics doses of 144 oral small-molecule drugs approved in Japan (2010-2021). The data on classic drugs were obtained from Goodman and Gilman's textbook, 9th ed. (published in 1996). Modern drugs had lower Ki (2.5 nM) and daily doses (88 μmol/day) than classic drugs (33 nM and 313 μmol/day), but 3.6-fold higher intrinsic clearance (CLint; 171 vs. 47 L/h), suggest that increasing potency over the years has not resulted in a reduction in dosage as expected. Estimating therapeutic doses using target receptor occupancy (tRO)-optimized approach improved estimation accuracy (63% within 10-fold of observed values) compared with tRO-fixed approaches. Subtherapeutic dose estimations revealed a risk of overdosing in FIH trials, indicating that these estimates are not necessarily as conservative as is generally understood. Notably, the unbound average concentration-to-Ki ratio (Cave,u/Ki) varied among drugs and correlated negatively with Ki, suggesting the possible necessity of incorporating it into dose estimation methods. This study provides insights into the relationship between invitro Ki, invivo PK parameters, and therapeutic dose of modern drugs, proposing strategies and revealing the risk for dose estimation and drug development in the era of highly potent small molecules.

Assessment of individual external exposure doses based on environmental radiation in areas affected by the Fukushima Daiichi Nuclear Power Station accident

Assessing individual external exposure doses from ambient dose equivalents is valuable for predictive and retrospective purposes when personal dosimeters are impractical. This study developed a model to assess individual external exposure doses from ambient dose equivalents, considering daily life patterns (location and time spent in various places), and evaluated parameters associated with individual external exposure doses, such as the reduction effects of radiation due to buildings and vehicles. The model parameters were evaluated using the robust datasets of environmental radiation measured in areas affected by the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The effective dose estimated by the model was compared to 106 daily personal dose equivalents measured using personal dosimeters in the residents’ living environments near the FDNPS. The estimated effective dose well consists with the measured personal dose equivalents, particularly when considering natural radiation in indoor dose estimation. This model is adequate for radiation protection, enabling the predictive and retrospective estimation of individual external exposure doses using environmental radiation monitoring data.

РЕЗУЛЬТАТЫ ДЛИТЕЛЬНОГО МЕДИЦИНСКОГО НАБЛЮДЕНИЯ НЕПОСРЕДСТВЕННЫХ УЧАСТНИКОВ АВАРИИ НА ЧАЭС В РОССИЙСКОЙ ФЕДЕРАЦИИ

Purpose: to present the materials of long-term (38 years) monitoring of the health status of a group of patients who had underwent acute radiation syndrome (ARS) in 1986 as a result of the Chernobyl accident and had been living in the territory of the Russian Federation. Materials and methods: the results of cytogenetic dynamic observation of 74 direct participants in the Chernobyl accident who had been examining at the clinic in the period from 1986 to 2012, as well as the results of dynamic inpatient observation of 10 of them permanently residing in Moscow, are summarized. Medical supervision consisted of annual planned hospitalizations in connection with patient requests, or emergency hospitalizations in connection with the detection of acute or exacerbation of a chronic disease. Laboratory and instrumental examination of organs and organ systems critical to the effects of radiation, as well as an extended cancer search, was carried out. Results: according to cytogenetic studies for all degrees of severity of ARS, starting from the 1st degree, the frequency of translocations in blood lymphocytes significantly exceeds the spontaneous level. The initial level of translocations depends on the initial dose estimate. The time of decrease in the frequency of translocations due to the presence of part of the translocations in unstable cells, from the initial value to an established constant level, apparently occurs in the first 5-8 years. Analysis of individual blood curves revealed transient moderate cytopenia, most often thrombocytopenia. Myelodysplastic syndrome (MDS) and leukemias were detected in 5 patients (2- Moscow group, 3- Ukranian group) from the entire group who underwent ARS as a result of the Chernobyl accident, which significantly exceeds the expected level. The diagnosis of radiation cataract was established in 11 patients. Two patients underwent surgical treatment. In the acute period ARS local radiation injuries (LRI) was detected in 59 patients. By 2005, 38 patients with the effects of LRI were observed (33 in Ukraine and 5 in Moscow). The most severe long-term consequences in the form of pronounced cicatricial atrophic changes, radiation fibrosis, and late radiation ulcers were detected in patients with grade III – IV LRI. 1 out of 10 observed patients developed primary multiple metachronous cancer of the genitourinary system, 2 patients – prostate cancer, 1 – metastatic lesion with an undetected primary tumor, 3 – multiple foci of basal cell skin cancer. The causes of death in 8 out of 10 patients were: cardiovascular pathology, MDS and leukemia, cirrhosis of the liver, oncological disease with undetected primary localization of the tumor, suicide in an oncological patient. Conclusions: The experience of providing medical care to victims of the Chernobyl accident with acute radiation injuries and further in the period of long-term consequences indicates the need to maintain constant readiness to provide medical care in case of a radiation accident, as well as adequate information during and after the accident, which will reduce the long-term consequences. Patients who have undergone ARS need lifelong medical supervision and the provision of necessary medical care. The main causes of permanent disability of patients who have undergone ARS are the consequences of LRI (recurrent late radiation ulcers, radiation fibrosis, contractures, scars, etc.). Radiation cataract is the cause of temporary disability (before surgical treatment). Patients who have undergone ARS need adequate social adaptation. The revealed effect of exposure to relatively uniform radiation is an increase in the frequency of MDS and leukemia.

Estimating occupational exposure in interventional radiology through Air Kerma Area Product - calculation of Effective Dose conversion factors

During interventional radiology procedures, interventionists are positioned close to the patient and directly exposed to ionizing radiation. This study presents a methodology to estimate the effective dose of interventionists through Air Kerma Area Product (PKA) in three interventional procedure modalities: coronary, cerebral, and peripheral. Optically stimulated luminescence dosimeters were used in several body regions (thyroid, eye lens, abdomen, feet, and hands) to assess equivalent doses and to convert external to internal doses – leading to effective doses related to each modality. These effective doses were then correlated to the total PKA given by the equipment. Thus, an effective dose estimate factor was calculated to represent the conversion between equipment parameters and the effective dose obtained from dosimeters, resulting in a novel methodology. The agreement between the methods was in the range of ± 0.13 μSv for angiographies and -8.3 to 5.3 μSv for angioplasties. These findings underscore the reliability of PKA as a predictor of effective dose, facilitating a rapid and precise assessment of occupational exposure in IR. This novel approach has the potential to enhance radiation safety protocols and optimize protection strategies for IR professionals, ensuring more accurate monitoring and control of radiation exposure in clinical settings.

Estimation of Organ Dose, Effective Dose, and Cancer Risk in Abdominal CT Scan Patients

Computed tomography scan (CT scan) is a modality that is used to diagnose diseases inside the human body. In the scanning process, the patient will receive radiation from the CT scanner, so that it is necessary to calculate the amount of radiation dose. The purpose of this study was to determine the organ dose, effective dose, and cancer risk received by abdominal examination patients. Data taken from the results of abdominal examination patients at Radiology Installation of A.W. Sjahranie Regional Hospital Samarinda using 16-slice CT scan modality GE BRIVO type D3161T. The data collected included 150 patients, both female and male, with ages ranging from 15 to 79 years. Dosimetry parameters taken from CT scan results are the exposure factor (kV, mAs), scan length, computed tomography dosimetry indeks volume (CTDIvol), and dose length product (DLP) of the patient. CTDIvol and DLP of the patient are used to calculate the organ dose, effective dose, and cancer risk values of abdominal CT scan patients. Then the effective dose value received by the abdominal CT scan examination patient is compared with the Nuclear Energy Regulatory Agency of Indonesia (BAPETEN) standard based on the CTDIvol and DLP values of the patient, and also compared with the International Commission Radiological Protection (ICRP) standard. Based on the results of organ dose estimation calculations, the average value of the stomach is 0.82 mSv, the gonads are 0.54 mSv, and the bladder is 0.28 mSv. Meanwhile, the average value of effective dose received by abdominal examination patients is 5.28 mSv with an average cancer risk of 0.029 %. Based on the CTDIvol and DLP values of the patients, the 3rd quartile values of the patients were 8.25 mGy and 413.84 mGy.cm. This value is still below the value recommended by BAPETEN when viewed from the 2021 Diagnostic Reference Level (DRL) guidelines. The effective dose received by one patient exceeded the standard set by the ICRP. Meanwhile, the cancer risk received by patients is still in a low percentage.

Estimation and analysis of S values for 131I using paediatric mesh type reference computational phantoms

This study examines the effect of paediatric mesh-type reference computational phantoms on organSvalues resulting from radioiodine (131I) intake. Using Geant4, we estimated131ISvalues for 30 radiosensitive target tissues due to emission from the thyroid (Target ← Thyroid) in these phantoms. Our results show thatSvalues differ between male and female phantoms of the same age andSvalues also decrease as phantom age increases. The male-to-femaleSvalue ratio typically varies within 10%, with larger differences observed for the esophagus, extra-thoracic regions, muscles, bladder, and sex organs. On average,Svalues for mesh phantoms are approximately 17% higher than those for voxel phantoms, with larger discrepancies for organs remodelled separately in mesh phantoms. The study provides organSvalues for the paediatric population due to131I exposure from the thyroid, based on the reference mesh-type computational phantoms, enhancing organ dose estimation in emergency situations and during radioiodine treatment.

Radon quantification in water and dose estimation via inhalation and ingestion across age groups in the Pattan region of North Kashmir, India.

Human survival hinges on access to water, which provides vital necessities. It is crucial to secure reliable, affordable, and uncontaminated water to maintain health and sustain life. For the potential impact of radioactive water pollution on human well-being, a scintillation-based smart RnDuo detector was employed in the Pattan region of North Kashmir Baramulla to quantify radon levels in diverse underground water. The dose contribution to various organs through inhalation and ingestion pathways has been analyzed. The study assesses the levels of radon in water, which varied from 19.88 to 74.37Bq/L with an average of 37.65Bq/L. All of the values were higher than the United States Environmental Protection Agency(USEPA) suggested guideline of 11Bq/L but lower than the 100Bq/L prescribed by the World Health Organization (WHO). The age group-wise inhalation and ingestion doses are higher than the 100 μSv/y recommended by WHO but within the prescribed range of 3-10mSv/y as suggested by the International Commission on Radiological Protection (ICRP). Doses to various organs (lungs and stomach) are also calculated in the present study. The results of the present investigation will help to enhance the quality of the water and guide future epidemiological studies.

Fast and precise dose estimation for very high energy electron radiotherapy with graph neural networks

IntroductionExternal beam radiotherapy (RT) is one of the most common treatments against cancer, with photon-based RT and particle therapy being commonly employed modalities. Very high energy electrons (VHEE) have emerged as promising candidates for novel treatments, particularly in exploiting the FLASH effect, offering potential advantages over traditional modalities.MethodsThis paper introduces a Deep Learning model based on graph convolutional networks to determine dose distributions of therapeutic VHEE beams in patient tissues. The model emulates Monte Carlo (MC) simulated doses within a cylindrical volume around the beam, enabling high spatial resolution dose calculation along the beamline while managing memory constraints.ResultsTrained on diverse beam orientations and energies, the model exhibits strong generalization to unseen configurations, achieving high accuracy metrics, including a δ-index 3% passing rate of 99.8% and average relative error &lt;1% in integrated dose profiles compared to MC simulations.DiscussionNotably, the model offers three to six orders of magnitude increased speed over full MC simulations and fast MC codes, generating dose distributions in milliseconds on a single GPU. This speed could enable direct integration into treatment planning optimization algorithms and leverage the model’s differentiability for exact gradient computation.

A mapping-free natural language processing-based technique for sequence search in nanopore long-reads

BackgroundIn unforeseen situations, such as nuclear power plant’s or civilian radiation accidents, there is a need for effective and computationally inexpensive methods to determine the expression level of a selected gene panel, allowing for rough dose estimates in thousands of donors. The new generation in-situ mapper, fast and of low energy consumption, working at the level of single nanopore output, is in demand. We aim to create a sequence identification tool that utilizes natural language processing techniques and ensures a high level of negative predictive value (NPV) compared to the classical approach.ResultsThe training dataset consisted of RNA sequencing data from 6 samples. Multiple natural language processing models were examined, differing in the type of dictionary components (word length, step, context) as well as the encoding length and number of sequences required for algorithm training. The best configuration analyses the entire sequence and uses a word length of 3 base pairs with one-word neighbor on each side. For the considered FDXR gene, the achieved mean balanced accuracy (BACC) was 98.29% and NPV was 99.25%, compared to minimap2’s performance in a cross-validation scenario. The next stage focused on exploring the dictionary components and attempting to optimize it, employing statistical techniques as well as those relying on the explainability of the decisions made. Reducing the dictionary from 1024 to 145 changed BACC to 96.49% and the NPV to 98.15%. Obtained model, validated on an external independent genome sequencing dataset, gave NPV of 99.64% for complete and 95.87% for reduced dictionary. The salmon-estimated read counts differed from the classical approach on average by 3.48% for the complete dictionary and by 5.82% for the reduced one.ConclusionsWe conclude that for long Oxford nanopore reads, a natural language processing-based approach can reliably replace classical mapping when there is a need for fast, reliable and energy and computationally efficient targeted mapping of a pre-defined subset of transcripts. The developed model can be easily retrained to identify selected transcripts and/or work with various long-read sequencing techniques. Our results of the study clearly demonstrate the potential of applying techniques known from classical text processing to nucleotide sequences.

Statistical-based modeling strategy for entrance skin dose estimation in patient undergoing body interventional radiology.

Interventional radiology (IR) provides significant advancements in diagnostic and therapeutic procedures, yet concerns persist regarding radiological risks such as erythema, burns, and epilation. Direct dose measurements observed difficulties regarding the perturbation of the detector probe in X-ray images during fluoroscopy-guided procedures, high-cost expenses, and non-compliant patients. This study aims to develop a statistical-based model for estimating entrance skin dose (ESD) in body IR procedures using patient radiation-dose recording data. Models are categorized into vascular and non-vascular procedures. This study demonstrates that the simplified models are sufficient in estimating patient ESDs for both IR groups, with a 95% confidence interval. This user-friendly method enables radiologists to calculate doses without complex parameters such as the backscatter factor and mass-energy absorption coefficient, as required in conventional calculation methods. It not only does this support to radiologists in effectively refining treatment protocols, but also enables patients to monitor their received doses immediately after treatment ends.