Results and analysis of examination doses for paediatric CT procedures based on a nationwide survey in China.

OBJECTIVE: To report the results of a dose survey conducted across 31 provinces in mainland China from 2017 to 2018 and to analyse the dose level to determine the national diagnostic reference levels (DRLs) for paediatric CT procedures. METHODS: At least ten patients for each age group (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) and each procedure (head, chest and abdomen) for each CT scanner were selected from four to eight hospitals in each province. The dose information (CTDIvol and DLP) was collected from the HIS or RIS-PACS systems. The median values in each CT scanner were considered the representative dose values for the paediatric patients in CT scanning. The national DRLs were estimated based on the 75th percentile distribution of the median values. RESULTS: A total of 24,395 patients and 319 CT scanners were investigated across 262 hospitals. For paediatric CT scanning in 4 different age groups, the median (P50) and the 75th percentile (P75) of CTDIvol and DLP for each scanning procedure were calculated and reported. National DRLs were then proposed for each procedure and age group. CONCLUSION: The dose level of CT scanning for children in mainland China was reported for the first time. The DRLs for paediatric CT in the present study are similar to those in some Asian countries but higher than those in European countries. CLINICAL RELEVANCE STATEMENT: The paediatric CT is an extensively used tool in diagnosing paediatric disease; however, children are more sensitive to radiation. Establishing the diagnostic reference level of paediatric CT examination is necessary to reduce the dose of CT in children and promote the optimisation of medical exposure. KEY POINTS: • The DRLs for 3 paediatric CT procedures (head, chest and abdomen) and 4 age groups (0- < 1, 1- < 5, 5- < 10, 10- < 15 years) were proposed in mainland China first time. • The examination parameter and dose for children need to be further optimised in China, especially to lower the tube voltage in paediatric CT.

Personal exposure to radiofrequency electromagnetic fields: A comparative analysis of international, national, and regional guidelines.

A worldwide overview and analysis for the existing limits of human exposure to Radiofrequency Electromagnetic Fields (RF-EMF) is given in this paper. These reference levels have been established by different national and even regional governments, which can be based on the guidelines provided by the recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP), the International Committee on Electromagnetic Safety of the Institute of Electrical and Electronics Engineers (IEEE), and even in the United States of the Federal Communications Commission (FCC), as well as, are based on the so-called precautionary principle. Explicit reference is made to the exposure limits adopted in countries or regions, such as Canada, Italy, Poland, Switzerland, China, Russia, France, and regions of Belgium (Brussels, Flanders, Wallonia), where the limits are much lower than the international standards. The limits are compared to a selected set of in-situ measurements. This clearly shows that the measured values are typically very small compared to the international standards but could be somewhat higher compared to the reduced limits. Based on this observation and the reasonable assumption that the sensitivity of people to Electromagnetic Fields (EMF) is the same everywhere (whole-body), we propose the idea to establish a worldwide reference limit for the general public, thus applicable in all countries, if the ICNIRP considers it appropriate. Research must continue to generate measurement data that demonstrate the levels of exposure to which we are really exposed, and with this, provide arguments to the organizations that established the guidelines, especially the ICNIRP, to evaluate whether the current limits are too much. High and can be modified when considered pertinent. To the best of our knowledge, at no time has the reference level for the general public been exceeded.

Radiation doses and diagnostic reference levels for common CT scans in adults in Northwest region of Iran.

This study aims to estimate organ dose and cancer risks, establish region-specific diagnostic reference levels (DRLs), and determine achievable doses (ADs) for common CT procedures in adults in the northwest of Iran. Effective and organ doses were estimated using VirtualDoseCT software in a sample of 480 adult patients who underwent head, sinus, chest, and abdomen-pelvis (AP) CT scans. The guidelines provided by the BEIR VII report were utilized to estimate cancer risks. Effective and organ doses for specific procedures were determined, with the highest mean organ dose being observed in the brain during head CT examinations, with a value of 54.02 mGy. It was observed that the lungs in chest examinations and the colon in AP examinations had the highest risk of cancer, with rates of 30.72 and 21.37 per 100,000 persons, respectively. Higher cancer risk values were generally exhibited by females compared to males. The DRLs for common CT examinations were established as follows: Head CT (CTDIvol 41 mGy, DLP 760 mGy cm), Sinus CT (CTDIvol 16 mGy, DLP 261 mGy cm), Chest CT (CTDIvol 8 mGy, DLP 287 mGy cm), and AP CT (CTDIvol 9 mGy, DLP 508 mGy cm). Significant variations in dose distribution among facilities were identified, indicating the need for optimization. The study highlights the importance of minimizing radiation exposure to critical organs and promoting patient safety in CT examinations. The establishment of region-specific DRLs and ADs can help optimize radiation doses and reduce cancer risks for patients.

Proposed DRLs for mammography in Switzerland.

The aim of this study is to propose diagnostic reference levels (DRLs) values for mammography in Switzerland. For the data collection, a survey was conducted among a sufficient number of centres, including five University hospitals, several cantonal hospitals, and large private clinics, covering all linguistic regions of Switzerland to be representative of the clinical practice. The data gathered contained the mean glandular dose (MGD), the compressed breast thickness (CBT), the mammography model and the examination parameters for each acquisition. The data collected was sorted into the following categories: 2D or digital breast tomosynthesis (DBT) examination, craniocaudal (CC) or mediolateral oblique (MLO) projection, and eight categories of CBT ranging from 20 mm to 100 mm in 10 mm intervals. A total of 24 762 acquisitions were gathered in 31 centres on 36 mammography units from six manufacturers. The analysis showed that the data reflects the practice in Switzerland. The results revealed that the MGD is larger for DBT than for 2D acquisitions for the same CBT. From 20-30 mm to 90-100 mm of CBT, the 75th percentile of the MGD values obtained increased from 0.81 mGy to 2.55 mGy for 2D CC acquisitions, from 0.83 mGy to 2.96 mGy for 2D MLO acquisitions, from 1.22 mGy to 3.66 mGy for DBT CC acquisitions and from 1.33 mGy to 4.04 mGy for DBT MLO acquisitions. The results of the survey allow us to propose Swiss DRLs for mammography according to the examination type (2D/DBT), projection (CC/MLO) and CBT. The proposed values are very satisfactory in comparison with other studies.

National survey to update the diagnostic reference levels in interventional radiology procedures in Italy: working methodology.

Interventional Radiology (IR) deals with the diagnosis and treatment of various diseases through medically guided imaging. It provides unquestionable benefits to patients, but requires, in many cases, the use of high doses of ionizing radiation with a high impact on radiation risks to patients and to overall dose to the population. The International Commission on Radiological Protection introduced Diagnostic reference levels (DRLs) as an effective tool to facilitate dose verification and optimize protection for patients undergoing radiological procedures. In addition, EURATOM Council Directive 2013/59 and its Italian transposition (Legislative Decree 101/2020) have reiterated that DRLs must be established for many common radiological diagnostic procedures to compare the radiation dose delivered for the same diagnostic examination. Within this framework, Istituto Superiore di Sanità-Italian National Institute of Health (ISS)-, in collaboration with relevant Italian Scientific Societies, has provided documents on DRLs in radiological practices such as diagnostic and IR and diagnostic nuclear medicine. These reference documents enable National Hospitals to comply national regulation. The implementation of DRLs in IR is a difficult task because of the wide distribution of doses to patients even within the same procedure. Some studies have revealed that the amount of radiation in IR procedures is influenced more by the complexity of the procedure than by the weight of the patient, so complexity should be included in the definition of DRLs. For this reason, ISS promoted a survey among a sample of Italian Centers update national DRL in IR procedures with related complexity factors than can be useful for other radiological centers and to standardize the DRLs values. In the present paper the procedural methodology developed by ISS and used for the survey will be illustrated.

Towards the establishment of national diagnostic reference levels for abdomen, KUB, and lumbar spine x-ray examinations in Sri Lanka: a multi-centric study.

Diagnostic reference levels (DRLs) and achievable doses (ADs) provide guidance to optimise radiation doses for patients undergoing medical imaging procedures. This multi-centre study aimed to compare institutional DRLs (IDRLs) across hospitals, propose ADs and multi-centric DRLs (MCDRLs) for four common x-ray examinations in Sri Lanka, and assess the potential for dose reduction. A prospective cross-sectional study of 894 adult patients referred for abdomen anteroposterior (AP), kidney-ureter-bladder (KUB) AP, lumbar spine AP, and lumbar spine lateral (LAT) x-ray examinations was conducted. Patient demographic information (age, sex, weight, BMI) and exposure parameters (tube voltage, tube current-exposure time product) were collected. Patient dose indicators were measured in terms of kerma-area product (PKA) using a PKAmeter. IDRLs, ADs, and MCDRLs were calculated following the International Commission on Radiological Protection guidelines, with ADs and MCDRLs defined as the 50th and 75th percentiles of the median PKAdistributions, respectively. IDRL ranges varied considerably across hospitals: 1.42-2.42 Gy cm2for abdomen AP, 1.51-2.86 Gy cm2for KUB AP, 0.83-1.65 Gy cm2for lumbar spine AP, and 1.76-4.10 Gy cm2for lumbar spine LAT. The proposed ADs were 1.82 Gy cm2(abdomen AP), 2.03 Gy cm2(KUB AP), 1.27 Gy cm2(lumbar spine AP), and 2.21 Gy cm2(lumbar spine LAT). MCDRLs were 2.24 Gy cm2(abdomen AP), 2.40 Gy cm2(KUB AP), 1.43 Gy cm2(lumbar spine AP), and 2.38 Gy cm2(lumbar spine LAT). Substantial intra- and inter-hospital variations in PKAwere observed for all four examinations. Although ADs and MCDRLs in Sri Lanka were comparable to those in the existing literature, the identified intra- and inter-hospital variations underscore the need for dose reduction without compromising diagnostic information. Hospitals with high IDRLs are recommended to review and optimise their practices. These MCDRLs serve as preliminary national DRLs, guiding dose optimisation efforts by medical professionals and policymakers.

Establishing national diagnostic reference levels in radiography, mammography, and dual-energy x-ray absorptiometry services in Ireland and comparing these with European diagnostic reference levels.

OBJECTIVES: The aim of this work was to establish national diagnostic reference levels (DRLs) in Ireland and compare these to existing European DRLs where available. This work surveyed all radiological facilities providing radiography, mammography, and dual-energy x-ray absorptiometry (DXA) services in Ireland. METHODS: A list of common procedures and clinical tasks was established. A national database of service providers was used to identify the appropriate medical radiological facilities providing these services. These facilities were issued with an online survey. National DRLs were set as the 75th percentile of the distribution of median values obtained. A national median dose was also established. The broad categorisation of equipment type was also considered. Where differences between DRLs established using different detector types were deemed statistically significant, equipment-specific national DRLs were established. RESULTS: National DRLs were established for 12 adult radiography projections. Equipment-specific (computed radiography and digital radiography) adult DRLs were established for four radiography projections. Paediatric DRLs were established for 11 radiography projections, including two based on clinical indications, for a range of paediatric weight categories. National DRLs were established for unilateral two-view mammography and breast tomosynthesis as well as for four DXA clinical indications and projections. All but one Irish DRL figure was found to be below or equal to European data. CONCLUSIONS: This work provided a unique opportunity to establish national DRLs based on census data for a range of procedures and clinical tasks across radiography, mammography and DXA and compare these with European levels. CLINICAL RELEVANCE STATEMENT: This work established national diagnostic reference levels (DRLs) based on census data for a range of procedures and clinical tasks across radiography, mammography and dual-energy x-ray absorptiometry. The establishment of national DRLs is an essential component in the optimisation of patient radiation dose. KEY POINTS: • Diagnostic reference levels are easily measured quantities intended for use as an aid to optimise patient dose and to identify when levels of patient dose are unusually high. • Data from all medical radiological facilities in Ireland was obtained to establish national diagnostic reference level (DRL) values and national median dose values in radiography, x-ray breast imaging and dual-energy x-ray absorptiometry (DXA) scanning and these were compared to existing European DRLs where available. • National DRL values were established for the first time in breast tomosynthesis, DXA scanning, and paediatric radiography.

Urinary levels of 30 metal/metalloids in the Brazilian southeast population: Findings from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

The assessment of risks associated with environmental exposure to metals/metalloids requires well-established reference values for each population since it varies considerably according to distinct local/regional characteristics. However, very few studies establish baseline values for these elements (essential and toxic) in large population groups, especially in Latin American countries. This study was aimed at establishing urinary reference levels of 30 metals/metalloids: aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), cadmium (Cd), cerium (Ce), cesium (Cs), chromium (Cr), cobalt (Co), copper (Cu), lanthanum (La), lead (Pb), lithium (Li), strontium (Sr), manganese (Mn), mercury (Hg), molybdenum (Mo), nickel (Ni), platinum (Pt), rubidium (Rb), selenium (Se), silver (Ag), tin (Sn), tellurium (Te), thallium (Tl), thorium (Th), tungsten (W), uranium (U) and zinc (Zn) in a Brazilian southeast adult population. This pilot study is a cross-sectional analysis conducted with the first wave of the ELSA-Brasil cohort (baseline examination). A total of 996 adults (45.5% men, N = 453, mean age: 50.5, and 54.5% women, N = 543, mean age: 50.6) were included in the study. Sample analyses were performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Percentiles (2.5, 10, 25, 50, 75, 95 (CI95%), and 97.5) of each element (µg/g of creatinine) in the study are presented according to sex. Moreover, differences in the mean metal/metalloid urinary levels according to age, education, smoking, and alcohol intake are also presented. Finally, median found values were compared to established values of large human biomonitoring surveys previously conducted in North America and France. This is the first comprehensive and systematic human biomonitoring study that established population reference ranges for 30 (essential and/or toxic elements) in a Brazilian population group.

Subclinical hypothyroidism in pregnancy - assessment of offspring thyroid status and mitochondrial robustness to stress.

Subclinical hypothyroidism's clinical implications on pregnancy are controversial. Consequently, thyrotropin (TSH) cutoff-values for pregnancy are continuously a subject for debate. In subclinical hypothyroidism, altered levels of thyroid hormones may affect mitochondrial function.Objectives were i) to analyze thyroid hormone levels in offspring of women with and without subclinical hypothyroidism ii) to analyze mitochondrial "robustness" in terms of MTG/TMRM ratio in pregnant women and their offspring in relation to thyroid function and iii) to perform differentiate analyses on different TSH thresholds to determine the importance of cutoff-values to results.Pregnant women were included by blood collections prior to a planned cesarean section, and cord samples were collected after delivery. Thyroid status (analyzed by Siemens Healthcare Diagnostics by an electrochemical luminescent immunoassay based on LOCI-technology) grouped the women and their offspring in euthyroid or subclinical hypothyroid, with groups established from previous recommended third-trimester cutoff-value (TSH > 3.0 mIU/L) and the recently recommended cutoff-value in Denmark (TSH > 3.7 mIU/L). Flow cytometric measurements of mitochondrial function in mononuclear blood cells with the fluorophores TetraMethylRhodamine Methyl Ester (TMRM) and Mitotracker Green (MTG) were used to evaluate mitochondrial robustness as the MTG/TMRM ratio.No significant differences in mitochondrial robustness between euthyroid and subclinical hypothyroid cohorts were observed, irrespective of TSH-cutoff applied. Maternal and cord MTG/TMRM ratios were positively correlated. Cord-TSH was elevated in subclinical hypothyroid offspring, independent of TSH cutoff applied. Cord-TSH was associated with maternal TSH-level, maternal smoking and cord arterial-pH.

Establishment of local diagnostic reference levels for common adult CT examinations: a multicenter survey in Addis Ababa.

BACKGROUND: In medical imaging, a computed tomography (CT) scanner is a major source of ionizing radiation. All medical radiation exposures should be justified and optimized to meet the clinical diagnosis. Thus, to avoid unnecessary radiation doses for patients, diagnostic reference levels (DRLs) have been used. The DRLs are used to identify unusually high radiation doses during CT procedures, which are not appropriate for the clinical diagnosis. It has been successfully implemented in Europe, Canada, Australia, the United States, several industrialized countries, and a few underdeveloped countries. The present study aimed to establish DRLs for the head, chest, and abdominopelvic (AP) CT procedures in Addis Ababa, Ethiopia. METHODS: A pilot study identified the most frequent CT examinations in the city. At the time of the pilot, eighteen CT scan facilities were identified as having functioning CT scanners. Then, on nine CT facilities (50% of functional CT scanners), a prospective analysis of volume CT dose index (CTDIvol) and dose length product (DLP) was performed. We collected data for 838 adult patients' head, chest, and AP CT examinations. SPSS version 25 was used to compute the median values of the DLP and CTDIvol dose indicators. The rounded 75th percentile of CTDIvol and DLP median values were used to define the DRLs. The results are compared to DRL data from the local, regional, and international levels. RESULT: The proposed DRLs using CTDIvol (mGy) are 53, 13, and 16 for the head, chest, and AP examinations respectively, while the DLP (mGy.cm) for the respective examinations were 1210, 635, and 822 mGy.cm. CONCLUSION: Baseline CT DRLs figures for the most frequently performed in Addis Ababa were provided. The discrepancies in dose between CT facilities and as well as between identical scanners suggests a large potential for dose optimization of examinations. This can be actually achieved through appropriate training of CT technologists and continuous dose audits.

Patient exposure dose in interventional cardiology per clinical and technical complexity levels. Part 1: results of the VERIDIC project.

BACKGROUND: Patients can be exposed to high skin doses during complex interventional cardiology (IC) procedures. PURPOSE: To identify which clinical and technical parameters affect patient exposure and peak skin dose (PSD) and to establish dose reference levels (DRL) per clinical complexity level in IC procedures. MATERIAL AND METHODS: Validation and Estimation of Radiation skin Dose in Interventional Cardiology (VERIDIC) project analyzed prospectively collected patient data from eight European countries and 12 hospitals where percutaneous coronary intervention (PCI), chronic total occlusion PCI (CTO), and transcatheter aortic valve implantation (TAVI) procedures were performed. A total of 62 clinical complexity parameters and 31 technical parameters were collected, univariate regressions were performed to identify those parameters affecting patient exposure and define DRL accordingly. RESULTS: Patient exposure as well as clinical and technical parameters were collected for a total of 534 PCI, 219 CTO, and 209 TAVI. For PCI procedures, body mass index (BMI), number of stents ≥2, and total stent length >28 mm were the most prominent clinical parameters, which increased the PSD value. For CTO, these were total stent length >57 mm, BMI, and previous anterograde or retrograde technique that failed in the same session. For TAVI, these were male sex, BMI, and number of diseased vessels. DRL values for Kerma-area product (PKA), air kerma at patient entrance reference point (Ka,r), fluoroscopy time (FT), and PSD were stratified, respectively, for 14 clinical parameters in PCI, 10 in CTO, and four in TAVI. CONCLUSION: Prior knowledge of the key factors influencing the PSD will help optimize patient radiation protection in IC.

Establishment of diagnostic reference levels in low-dose renal computed tomography.

BACKGROUND: Increased radiation doses from computed tomography (CT) examinations is well known with proven risks of inducing cancers for effective dose >100 mSv (according to some studies >50 mSvs). PURPOSE: To establish the diagnostic reference level (DRL) for low-dose renal CT examinations in the evaluation of renal stones. MATERIAL AND METHODS: Patient demographics, CT parameters, and dosimetric indices (CTDIvol and dose length product [DLP]) were collected from 12 tertiary hospitals that routinely perform renal CT in the detection and evaluation of renal stones over a period of 12 weeks. Data obtained from 1418 average-sized patients in each category were recorded. The median values of dosimetric indices for each site were calculated. The DRL values were defined as the 75th percentile of the distribution of the median values of CTDIvol and DLP. RESULTS: There were no significant differences between patient demographics. Mean kVp and mAs for protocols were 121.67 ± 11.56 and 226.91 ± 78.44, respectively. The CTDIvol values were in the range of 2-36.2 mGy, while the DLP values were in the range of 43-1942 mGy.cm. The DRL for the CTDIvol was 16.15 mGy and for the DLP 851.77 mGy.cm. The local median values of CDTIvol and DLP are higher than DRL in two hospitals. CONCLUSION: Comparison of local median values of CDTIvol and DLP with DRL suggests the needs of an optimization strategy in some hospitals.

Local reference and achievable dose levels for vascular and enterostomy access procedures in pediatric interventional radiology.

BACKGROUND: Knowledge of radiation quantities delivered in routine practice is an essential responsibility of a pediatric interventional radiology department. OBJECTIVE: To review radiation indices in frequently performed vascular and enterostomy access procedures at a quaternary pediatric hospital to formulate dosimetric reference levels and achievable levels. MATERIALS AND METHODS: A retrospective review of patient demographics, procedure information and quantitative dose metrics over a 2-year period was performed. Dosimetric details for common procedures (central line insertions, gastrostomy/gastrojejunostomy insertions and maintenance) were evaluated, correlated with demographic data and stratified across five weight groups (0-5 kg, 5-15 kg, 15-30 kg, 30-50 kg, 50-80 kg). Achievable (50th percentile) and reference (75th percentile) levels with confidence intervals were established for each procedure. RESULTS: Within the evaluation period, 3,165 studies satisfied the inclusion criteria. Five were classified as device insertions (peripherally inserted central catheter, n=1,145; port-a-catheter, n=321; central venous line, n=285; gastrostomy-tube [G-tube], n=262, and gastrojejunostomy-tube [GJ-tube], n=66), and two were classified as maintenance procedures (G-tube, n=358, and GJ-tube, n=728, checks, exchanges and reinsertions). Representative reference and achievable levels were calculated for each procedure category and weight group. CONCLUSION: This work highlights the creation of local reference and achievable levels for common pediatric interventional procedures. These data establish a dosimetric reference to understand the quantity of radiation routinely applied, allowing for improved relative radiation risk assessment and enriched communication to interventionalists, health care providers, parents and patients.

Assessment of diagnostic reference levels for paediatric cardiac computed tomography in accordance with European guidelines.

Recently, paediatric cardiac computed tomography (CCT) has caused concerns that diagnostic image quality and dose reduction may require further improvement. Consequently, this study aimed to establish institutional (local) diagnostic reference levels (LDRLs) for CCT for paediatric patients, and assess the impact of tube voltage on proposed DRLs in terms of the volume computed tomography index (CTDIvol) and dose length product (DLP). In addition, effective doses (EDs) of exposure were estimated. A population of 453 infants, whose mass and age were less than 12 kg and 2 years, respectively, were considered from January 2018 to August 2021. Based on previous studies, this number of patients was considered to be sufficient for establishing LDRLs. A group of 245 patients underwent CCT examinations at 70 kVp tube voltage with an average scan range of 23.4 cm. Another set of 208 patients underwent CCT examinations at 100 kVp tube voltage with an average scan range of 15.8 cm. The observed CTDIvol and DLP values were 2.8 mGy and 54.8 mGy.cm, respectively. The mean effective dose (ED) was 1.2 mSv. It is concluded that provisional establishment and use of DRLs for cardiac computed tomography in children are crucial, and further research is needed to develop regional and international DRLs.

Attributable patient risk in nuclear medicine procedures and establishment of diagnostic reference levels.

The assessment of risk related to medical exposures as a justification tool to assist decision-making of the medical team is not available in clinical routine. The determination of diagnostic reference levels (DRLs) for nuclear medicine (NM) procedures has been proposed as an optimization tool, but this tool has still been aimed at a standard adult individual. It is known that the activity administered, and the consequent absorbed doses in critical organs, represents the risk of a procedure being cancer induction the greatest concern, especially for young patients. Thus, the adjustment of administered activity and procedure risk to promote risk-benefit assessment is a promising tool for routine clinical use. This work aims to present a tool for determining DRLs in the administered activity related to the patient's characteristics-age group, sex, and body mass index (BMI), in order to assist the medical decision regarding the risk-benefit ratio. Thus, it is possible to assess the risk of carcinogenesis in groups of patients, considering absorbed doses in organs, cancer incidence, and mortality rates in our country. NIREA is an IT tool developed in PHP language for web environment as a friendly software. It allows the establishment of DRL and risk of cancer induced by radiation assessment through the estimation of absorbed doses in specific organs and based on the risk methodology of BEIR VII. The absorbed and effective doses were estimated based on the dose conversion factors of the radiopharmaceuticals published by the International Commission on Radiological Protection adjusted for the patient groups. Based on data from 2256 patients who underwent diagnostic procedures at National Cancer Institute between 2017 and 2019, the program was used, resulting in important information for conducting the clinical routine extracted as DRL, absorbed doses, and risk assessments, considering patient-specific data such as age, sex, and BMI. The methodology developed in this work allows NM services to keep their data available and updated regarding local DRLs, in addition to allowing the nuclear physician to know the risk of each procedure performed, extracted by individual characteristics of the patient. The affirmative is significant because the data could be used by the regulatory body of practices with ionizing radiation in Brazil to establish a reference level in Activity that has not yet existed in the country.

Deep learning-based body weight from scout images can be an alternative to actual body weight in CT radiation dose management.

PURPOSE: Accurate body weight measurement is essential to promote computed tomography (CT) dose optimization; however, body weight cannot always be measured prior to CT examination, especially in the emergency setting. The aim of this study was to investigate whether deep learning-based body weight from chest CT scout images can be an alternative to actual body weight in CT radiation dose management. METHODS: Chest CT scout images and diagnostic images acquired for medical checkups were collected from 3601 patients. A deep learning model was developed to predict body weight from scout images. The correlation between actual and predicted body weight was analyzed. To validate the use of predicted body weight in radiation dose management, the volume CT dose index (CTDIvol ) and the dose-length product (DLP) were compared between the body weight subgroups based on actual and predicted body weight. Surrogate size-specific dose estimates (SSDEs) acquired from actual and predicted body weight were compared to the reference standard. RESULTS: The median actual and predicted body weight were 64.1 (interquartile range: 56.5-72.4) and 64.0 (56.3-72.2) kg, respectively. There was a strong correlation between actual and predicted body weight (ρ = 0.892, p < 0.001). The CTDIvol and DLP of the body weight subgroups were similar based on actual and predicted body weight (p < 0.001). Both surrogate SSDEs based on actual and predicted body weight were not significantly different from the reference standard (p = 0.447 and 0.410, respectively). CONCLUSION: Predicted body weight can be an alternative to actual body weight in managing dose metrics and simplifying SSDE calculation. Our proposed method can be useful for CT radiation dose management in adult patients with unknown body weight.

Sievert or Gray: Dose Quantities and Protection Levels in Emergency Exposure.

Mitigation or even elimination of adverse effects caused by ionizing radiation is the main scope of the radiation protection discipline. The interaction of radiation with living matter is quantified and correlated with biological effects by dose. The Sievert is the most well-known quantity, and it is used with the equivalent and effective dose to minimize stochastic effects. However, Gray is the reference quantity for sizing tissue reactions that could occur under high-exposure conditions such as in a radiation emergency. The topics addressed in this review are the choice to move from Sievert to Gray, how the operational quantities for environmental and individual monitoring of the detectors should consider such a change of units, and why reference levels substitute dose levels in emergency exposure.

Towards the establishment of national diagnostic reference levels for chest x-ray examinations in Sri Lanka: a multi-centric study.

The establishment of diagnostic reference levels (DRLs) is an effective tool for optimising radiation doses delivered to patients during medical imaging procedures. This study aimed to compare the institutional DRLs (IDRLs) and propose a multi-centric diagnostic reference level (MCDRL) for chest x-ray examinations in adult patients in Sri Lanka. A prospective cross-sectional study was conducted with 1091 adult patients across six major tertiary care hospitals. Data on patient characteristics, such as age, sex, weight, and body mass index, and exposure parameters, such as tube voltage (kVp) and the product of tube current and exposure time (mAs), were collected. Patient doses were measured in terms of kerma-area product (PKA) using a PKAmeter mounted on the collimator of the x-ray tube. IDRLs were computed for each hospital according to the International Commission on Radiological Protection guidelines, and the 75th percentile PKAwas used to propose the MCDRL. The relationship between patient weight and exposure parameters was examined using Spearman's rank correlation to investigate the radiographic practice among hospitals. Results showed that IDRLs varied from 0.10 to 0.26 Gy cm2. The proposed MCDRL was 0.23 Gy cm2, substantially higher than the recently published DRLs from other countries. The median kVp ranged from 95 to 104, while mAs ranged from 2.5 to 5.6. Large variations in the PKAand exposure parameters were observed within and among hospitals. The elevated PKAvalues observed in this study were mostly due to the use of high mAs in clinical practice. The weak correlation observed between patient weight and exposure parameters suggests the need to standardise examination protocols concerning patient size. The observed dose variations demonstrate the need for the establishment of national DRLs. Until then, the proposed MCDRL can be considered as the benchmark dose level for chest x-ray examinations in Sri Lanka.

Mass spectrometric study of variation in kinin peptide profiles in nasal fluids and plasma of adult healthy individuals.

BACKGROUND: The kallikrein-kinin system is assumed to have a multifunctional role in health and disease, but its in vivo role in humans currently remains unclear owing to the divergence of plasma kinin level data published ranging from the low picomolar to high nanomolar range, even in healthy volunteers. Moreover, existing data are often restricted on reporting levels of single kinins, thus neglecting the distinct effects of active kinins on bradykinin (BK) receptors considering diverse metabolic pathways. A well-characterized and comprehensively evaluated healthy cohort is imperative for a better understanding of the biological variability of kinin profiles to enable reliable differentiation concerning disease-specific kinin profiles. METHODS: To study biological levels and variability of kinin profiles comprehensively, 28 healthy adult volunteers were enrolled. Nasal lavage fluid and plasma were sampled in customized protease inhibitor prespiked tubes using standardized protocols, proven to limit inter-day and interindividual variability significantly. Nine kinins were quantitatively assessed using validated LC-MS/MS platforms: kallidin (KD), Hyp4-KD, KD1-9, BK, Hyp3-BK, BK1-8, BK1-7, BK1-5, and BK2-9. Kinin concentrations in nasal epithelial lining fluid were estimated by correlation using urea. RESULTS: Circulating plasma kinin levels were confirmed in the very low picomolar range with levels below 4.2 pM for BK and even lower levels for the other kinins. Endogenous kinin levels in nasal epithelial lining fluids were substantially higher, including median levels of 80.0 pM for KD and 139.1 pM for BK. Hydroxylated BK levels were higher than mean BK concentrations (Hyp3-BK/BK = 1.6), but hydroxylated KD levels were substantially lower than KD (Hyp4-KD/KD = 0.37). No gender-specific differences on endogenous kinin levels were found. CONCLUSIONS: This well-characterized healthy cohort enables investigation of the potential of kinins as biomarkers and would provide a valid control group to study alterations of kinin profiles in diseases, such as angioedema, sepsis, stroke, Alzheimer's disease, and COVID-19.

Assessment of task-based image quality for abdominal CT protocols linked with national diagnostic reference levels.

OBJECTIVES: To assess task-based image quality for two abdominal protocols on various CT scanners. To establish a relationship between diagnostic reference levels (DRLs) and task-based image quality. METHODS: A protocol for the detection of focal liver lesions was used to scan an anthropomorphic abdominal phantom containing 8- and 5-mm low-contrast (20 HU) spheres at five CTDIvol levels (4, 8, 12, 16, and 20 mGy) on 12 CTs. Another phantom with high-contrast calcium targets (200 HU) was scanned at 2, 4, 6, 10, and 15 mGy using a renal stones protocol on the same CTs. To assess the detectability, a channelized Hotelling observer was used for low-contrast targets and a non-prewhitening observer with an eye filter was used for high contrast targets. The area under the ROC curve and signal to noise ratio were used as figures of merit. RESULTS: For the detection of 8-mm spheres, the image quality reached a high level (mean AUC over all CTs higher than 0.95) at 11 mGy. For the detection of 5-mm spheres, the AUC never reached a high level of image quality. Variability between CTs was found, especially at low dose levels. For the search of renal stones, the AUC was nearly maximal even for the lowest dose level. CONCLUSIONS: Comparable task-based image quality cannot be reached at the same dose level on all CT scanners. This variability implies the need for scanner-specific dose optimization. KEY POINTS: • There is an image quality variability for subtle low-contrast lesion detection in the clinically used dose range. • Diagnostic reference levels were linked with task-based image quality metrics. • There is a need for specific dose optimization for each CT scanner and clinical protocol.