Global impacts of an extreme solar particle event under different geomagnetic field strengths.

Solar particle events (SPEs) are short-lived bursts of high-energy particles from the solar atmosphere and are widely recognized as posing significant economic risks to modern society. Most SPEs are relatively weak and have minor impacts on the Earth's environment, but historic records contain much stronger SPEs which have the potential to alter atmospheric chemistry, impacting climate and biological life. The impacts of such strong SPEs would be far more severe when the Earth's protective geomagnetic field is weak, such as during past geomagnetic excursions or reversals. Here, we model the impacts of an extreme SPE under different geomagnetic field strengths, focusing on changes in atmospheric chemistry and surface radiation using the atmosphere-ocean-chemistry-climate model SOCOL3-MPIOM and the radiation transfer model LibRadtran. Under current geomagnetic conditions, an extreme SPE would increase NOx concentrations in the polar stratosphere and mesosphere, causing reductions in extratropical stratospheric ozone lasting for about a year. In contrast, with no geomagnetic field, there would be a substantial increase in NOx throughout the entire atmosphere, resulting in severe stratospheric ozone depletion for several years. The resulting ground-level ultraviolet (UV) radiation would remain elevated for up to 6 y, leading to increases in UV index up to 20 to 25% and solar-induced DNA damage rates by 40 to 50%. The potential evolutionary impacts of past extreme SPEs remain an important question, while the risks they pose to human health in modern conditions continue to be underestimated.

The addition of a leaded arm sleeve to leaded aprons further decreases operator upper outer quadrant chest wall radiation dose during fluoroscopically guided interventions.

OBJECTIVE: Breast cancer most commonly occurs in the upper outer quadrant (UOQ) chest wall (CW). The effectiveness of routine leaded aprons to protect this region of the body in interventionalists during fluoroscopically guided interventions (FGIs) is unknown. Given the high lifetime attributable risks of prolonged occupational exposure to ionizing radiation and the increasing number of practicing female vascular surgeons and interventionalists, we sought to determine if the use of a leaded arm shield would offer additional protection to the lateral CW and axilla in operators compared with routine leaded aprons. METHODS: Effectiveness of leaded sleeves in attenuating radiation dose to the axilla and UOQ was evaluated in clinical practice and simulated scenarios. In the clinical setting, optically stimulated luminescence nanoDot detectors were placed at the UOQ lateral CW position, both over and under a standard leaded apron vest with and without the addition of an antimony/bismuth Enviro-Lite sleeve on two vascular surgeons performing FGIs. In the simulation, nanoDots were similarly placed on an anthropomorphic phantom positioned to represent a primary operator performing right femoral access. Fluorography was performed on 12-inch-thick acrylic scatter phantom at 80 kVp for an exposure of 3 Gy reference air kerma. Experiments were done with and without the sleeve. Paired Wilcoxon and χ2 tests were performed to identify the statistical significance of radiation attenuation. RESULTS: Operator UOQ CW dose was measured during 61 FGIs: 33 cases (54%) with and 28 cases (46%) without the sleeve. Median procedure reference air kerma and fluoroscopy time was 180 mGy (interquartile range [IQR], 85-447 mGy) and 21 minutes (IQR, 11-39 minutes) when the sleeve was worn vs 100 mGy (IQR, 67-270 mGy) and 11 minutes (IQR, 6.3-25 minutes) without the sleeve. Radiation dose to the operator's UOQ was reduced by 96% (IQR, 85%-96%) when the sleeve was present and by 62% (IQR, 44%-82%; P < .001) without the sleeve. In the simulated setting, the sleeve reduced the radiation dose to the UOQ compared with the apron alone (96% vs 67%; P < .001). CONCLUSIONS: Routine leaded aprons do attenuate the majority of UOQ chest wall radiation dose; however, the addition of a lead-equivalent sleeve further significantly reduces this dose. Because this area of the body has a high incidence of cancer formation, additional protection, especially to female interventionalists, seems prudent. Vascular surgeons should consider using a protective sleeve with their personal protective equipment when performing complex fluoroscopically guided procedures.

The influence of different radiotherapy doses on the mechanical properties and microstructure of the enamel and dentin of human premolar teeth.

OBJECTIVE: Radiation therapy is applied in the treatment of head and neck cancer patients. However, oral-health-related side effects like hyposalivation and a higher prevalence of caries have been shown. This study aims to assess the influence of different radiotherapy doses on the mechanical properties, roughness, superficial microstructure, and crystallinity of the enamel and dentin of human premolar teeth. METHODS: Specimens (n = 25) were categorized into five groups based on the radiation dose received (0, 10, 30, 50, and 70 Gy). The enamel and dentin of these specimens were subjected to a microhardness tester, profilometer, atomic force microscopy (AFM), scanning electron microscopy (SEM), and X­ray diffraction (XRD) before and after different irradiation doses and compared to hydroxylapatite in each group. The data were analyzed using repeated-measures analysis of variance (ANOVA). RESULTS: Therapeutic radiation doses of 30, 50, and 70 Gy led to a decrease in the microhardness and an increase in the average roughness of the enamel, and rougher surfaces were observed in the mixed three-dimensional images. Moreover, in the dentin, a similar outcome could be observed for more than 10 Gy. The main crystalline phase structure remained hydroxylapatite, but the crystallinity decreased and the crystalline size increased above 10 Gy. The superficial micromorphology revealed granulation, fissures, and cracks in a dose-dependent manner. Radiation below 70 Gy had little effect on the hydroxylapatite concentration during the whole experiment. CONCLUSION: Above a radiation dose of 30 Gy, the micromorphology of the tooth enamel changed. This occurred for dentin above 10 Gy, which indicates that dentin is more sensitive to radiotherapy than enamel. The radiation dose had an effect on the micromorphology of the hard tissues of the teeth. These results illustrate the possible mechanism of radiation-related caries and have guiding significance for clinical radiotherapy.

Effect of simultaneous integrated boost concepts on photoneutron and distant out-of-field doses in VMAT for prostate cancer.

BACKGROUND: A simultaneous integrated boost (SIB) may result in increased out-of-field (DOOF) and photoneutron (HPN) doses in volumetric modulated arc therapy (VMAT) for prostate cancer (PCA). This work therefore aimed to compare DOOF and HPN in flattened (FLAT) and flattening filter-free (FFF) 6­MV and 10-MV VMAT treatment plans with and without SIB. METHODS: Eight groups of 30 VMAT plans for PCA with 6 MV or 10 MV, with or without FF and with uniform (2 Gy) or SIB target dose (2.5/3.0 Gy) prescriptions (CONV, SIB), were generated. All 240 plans were delivered on a slab-phantom and compared with respect to measured DOOF and HPN in 61.8 cm distance from the isocenter. The 6­ and 10-MV flattened VMAT plans with conventional fractionation (6- and 10-MV FLAT CONV) served as standard reference groups. Doses were analyzed as a function of delivered monitor units (MU) and weighted equivalent square field size Aeq. Pearson's correlation coefficients between the presented quantities were determined. RESULTS: The SIB plans resulted in decreased HPN over an entire prostate RT treatment course (10-MV SIB vs. CONV -38.2%). Omission of the flattening filter yielded less HPN (10-MV CONV -17.2%; 10-MV SIB -22.5%). The SIB decreased DOOF likewise by 39% for all given scenarios, while the FFF mode reduced DOOF on average by 60%. A strong Pearson correlation was found between MU and HPN (r > 0.9) as well as DOOF (0.7 < r < 0.9). CONCLUSION: For a complete treatment, SIB reduces both photoneutron and OOF doses to almost the same extent as FFF deliveries. It is recommended to apply moderately hypofractionated 6­MV SIB FFF-VMAT when considering photoneutron or OOF doses.

Long-term trends in total administered radiation dose from brain [18F]FDG-PET in children with drug-resistant epilepsy.

PURPOSE: To assess the trends in administered 2-[18F]fluoro-2-deoxy-D-glucose ([18F]FDG) doses, computed tomography (CT) radiation doses, and image quality over the last 15 years in children with drug-resistant epilepsy (DRE) undergoing hybrid positron emission tomography (PET) brain scans. METHODS: We retrospectively analyzed data from children with DRE who had [18F]FDG-PET/CT or magnetic resonance scans for presurgical evaluation between 2005 and 2021. We evaluated changes in injected [18F]FDG doses, administered activity per body weight, CT dose index volume (CTDIvol), and dose length product (DLP). PET image quality was assessed visually by four trained raters. Conversely, CT image quality was measured using region-of-interest analysis, normalized by signal-to-noise (SNR) and contrast-to-noise ratio (CNR). RESULTS: We included 55 children (30 male, mean age: 9 ± 6 years) who underwent 61 [18F]FDG-PET scans (71% as PET/CT). Annually, the injected [18F]FDG dose decreased by ~ 1% (95% CI: 0.92%-0.98%, p < 0.001), with no significant changes in administered activity per body weight (p = 0.51). CTDIvol and DLP decreased annually by 16% (95% CI: 9%-23%) and 15% (95% CI: 8%-21%, both p < 0.001), respectively. PET image quality improved by 9% year-over-year (95% CI: 6%-13%, p < 0.001), while CT-associated SNR and CNR decreased annually by 7% (95% CI: 3%-11%, p = 0.001) and 6% (95% CI: 2%-10%, p = 0.008), respectively. CONCLUSION: Our findings indicate stability in [18F]FDG administered activity per body weight alongside improvements in PET image quality. Conversely, CT-associated radiation doses reduced. These results reaffirm [18F]FDG-PET as an increasingly safer and higher-resolution auxiliary imaging modality for children with DRE. These improvements, driven by technological advancements, may enhance the diagnostic precision and patient outcomes in pediatric epilepsy surgery.

To shield or not to shield: shielding may have unintended effects on patient dose in CT.

OBJECTIVES: The aim of the patient out-of-plane shield is to reduce the patient radiation dose. Its effect on tube current modulation was evaluated with the out-of-plane shield visible in the localizer but absent in the scan range in chest CT with different CT scanners. METHODS: An anthropomorphic phantom was scanned with six different CT scanners from three different vendors. The chest was first scanned without any shielding, and then with the out-of-plane shield within the localizer but outside the imaged volume. All pitch values of each scanner were used. The tube current values with and without the out-of-plane shield were collected and used to evaluate the effect of overscanning and tube current modulation (TCM) on patient radiation dose. RESULTS: The highest increase in cumulative mA was 217%, when the pitch was 1.531. The tube current value increased already 8.9 cm before the end of the scanned anatomy and the difference between the tube current of the last slices (with and without the out-of-plane shield in the localizer) was 976%. CONCLUSION: Applying an out-of-plane shield outside the scanned volume but visible in the localizer images may increase the patient dose considerably if the scanner's TCM function is based only on localizer images. CLINICAL RELEVANCE STATEMENT: The use of an out-of-plane shield in CT may strongly increase the tube current modulation and thus provide the patient with a higher radiation dose. KEY POINTS: • Applying an out-of-plane shield outside the scanned volume but visible in the localizer images may increase patient radiation dose considerably. • The effect is visible with scanners that use solely localizer-based tube current modulation. • Features like overscanning may be difficult for the user to notice when planning the scanning, and yet they may affect tube current modulation and through it to patient dose.

Image quality of lung perfusion with photon-counting-detector CT: comparison with dual-source, dual-energy CT.

PURPOSE: To evaluate the quality of lung perfusion imaging obtained with photon-counting-detector CT (PCD-CT) in comparison with dual-source, dual-energy CT (DECT). METHODS: Seventy-one consecutive patients scanned with PCD-CT were compared to a paired population scanned with dual-energy on a 3rd-generation DS-CT scanner using (a) for DS-CT (Group 1): collimation: 64 × 0.6 × 2 mm; pitch: 0.55; (b) for PCD-CT (Group 2): collimation: 144 × 0.4 mm; pitch: 1.5; single-source acquisition. The injection protocol was similar in both groups with the reconstruction of perfusion images by subtraction of high- and low-energy virtual monoenergetic images. RESULTS: Compared to Group 1, Group 2 examinations showed: (a) a shorter duration of data acquisition (0.93 ± 0.1 s vs 3.98 ± 0.35 s; p < 0.0001); (b) a significantly lower dose-length-product (172.6 ± 55.14 vs 339.4 ± 75.64 mGy·cm; p < 0.0001); and (c) a higher level of objective noise (p < 0.0001) on mediastinal images. On perfusion images: (a) the mean level of attenuation did not differ (p = 0.05) with less subjective image noise in Group 2 (p = 0.049); (b) the distribution of scores of fissure visualization differed between the 2 groups (p < 0.0001) with a higher proportion of fissures sharply delineated in Group 2 (n = 60; 84.5% vs n = 26; 26.6%); (c) the rating of cardiac motion artifacts differed between the 2 groups (p < 0.0001) with a predominance of examinations rated with mild artifacts in Group 2 (n = 69; 97.2%) while the most Group 1 examinations showed moderate artifacts (n = 52; 73.2%). CONCLUSION: PCD-CT acquisitions provided similar morphologic image quality and superior perfusion imaging at lower radiation doses. CLINICAL RELEVANCE STATEMENT: The improvement in the overall quality of perfusion images at lower radiation doses opens the door for wider applications of lung perfusion imaging in clinical practice. KEY POINTS: The speed of data acquisition with PCD-CT accounts for mild motion artifacts. Sharply delineated fissures are depicted on PCD-CT perfusion images. High-quality perfusion imaging was obtained with a 52% dose reduction.

Diagnostic reference levels in interventional neuroradiology procedures - a systematic review.

INTRODUCTION: The establishment of diagnostic reference levels (DRLs) is challenge for interventional neuroradiology (INR) due to the complexity and variability of its procedures. OBJECTIVE: The main objective of this systematic review is to analyse and compare DRLs in fluoroscopy-guided procedures in INR. METHODS: An observational study reporting DRLs in INR procedures, specifically cerebral arteriography, cerebral aneurysm embolisation, cerebral thrombectomy, embolisation of arteriovenous malformations (AVM), arteriovenous fistulas (AVF), retinoblastoma embolisation, and spinal cord arteriography. Comprehensive literature searches for relevant studies published between 2017 and 2023 were conducted using the Scopus, PubMed, and Web of Science databases. RESULTS: A total of 303 articles were identified through an extensive literature search, with 159 removed due to duplication. The title and abstract of 144 studies were assessed and excluded if they did not meet the inclusion criteria. Thirty-one out of the 144 articles were selected for a thorough full-text screening. Twenty-one articles were included in the review after the complete text screening. CONCLUSION: The different conditions of patients undergoing INR procedures pose a barrier to the standardization of DRLs; nevertheless, they are extremely important for monitoring and optimising radiological practices.

Comparison of 96-kV and 120-kV cone-beam CT for the assessment of cochlear implants.

BACKGROUND: To compare the diagnostic value of 120-kV with conventional 96-kV Cone-Beam CT (CBCT) of the temporal bone after cochlear implant (CI) surgery. METHODS: This retrospective study included CBCT scans after CI surgery between 06/17 and 01/18. CBCT allowed examinations with 96-kV or 120-kV; other parameters were the same. Two radiologists independently evaluated following criteria on 5-point Likert scales: osseous spiral lamina, inner and outer cochlear wall, semi-circular canals, mastoid trabecular structure, overall image quality, metal and motion artefacts, depiction of intracochlear electrode position and visualisation of single electrode contacts. Effective radiation dose was assessed. RESULTS: Seventy-five patients (females, n = 39 [52.0%], mean age, 55.8 ± 16.5 years) were scanned with 96-kV (n = 32, 42.7%) and 120-kV (n = 43, 57.3%) protocols including CI models from three vendors (vendor A n = 7; vendor B n = 43; vendor C n = 25). Overall image quality, depiction of anatomical structures, and electrode position were rated significantly better in 120-kV images compared to 96-kV (all p < = 0.018). Anatomical structures and electrode position were rated significantly better in 120-kV CBCT for CI models from vendor A and C, while 120-kV did not provide improved image quality in CI models from vendor B. Radiation doses were significantly higher for 120-kV scans compared to 96-kV (0.15 vs. 0.08 mSv, p < 0.001). CONCLUSIONS: 120-kV and 96-kV CBCT provide good diagnostic images for the postoperative CI evaluation. While 120-kV showed improved depiction of temporal bone and CI electrode position compared to 96-kV in most CI models, the 120-kV protocol should be chosen wisely due to a substantially higher radiation exposure.

A new era of high-resolution CT diagnostics of the lung: improved image quality, detailed morphology, and reduced radiation dose with high-resolution photon-counting CT of the lungs compared to high-resolution energy-integrated CT.

BACKGROUND: High-resolution computed tomography (HRCT) is dependent on detailed morphology in diagnostic assessment of interstitial lung diseases. Photon-counting CT (PCCT) enables improved resolution while reducing radiation. PURPOSE: To compare if the image quality, detailed morphology, and radiation dose in HRCT of the lung improves with PCCT compared to energy-integrated CT (EICT). MATERIAL AND METHODS: HRCT with PCCT in patients with body mass index (BMI) from normal to obese, previously examined with different EICT were included. They were evaluated in a five-step scale for image quality according to Quality Criteria for CT (Diagnostic Requirement of the ImPACT group-European standardization). In addition, ground-glass opacities, bronchiectasis, emphysema, nodules, and subpleural detailed morphology (≤1 cm from the pleural border) were evaluated by three independent thoracic and/or pediatric radiologists. Visual grading characteristics (VGC) were used for comparison of image quality and detailed morphology and Fleiss kappa for intra-observer variability. Dose-length product (DLP) and CT dose index-volume (CTDIvol) were collected to calculate effective radiation dose. RESULTS: HRCT with PCCT in 52 women and 48 men (mean age=67.2 ± 13.6 years; age range=27-87 years; BMI=26.9 kg/m2; range=18.6-45 kg/m2) previously examined with EICT (mean age=65.3 ± 13.6 years; age range=27-85 years; BMI=27 kg/m2; range=18.9-45 kg/m2) were included. There were significant differences in image quality for all entities in favor of PCCT. The radiation dose was reduced with PCCT by 47% in all, particularly pronounced in obese with 48.5%. CONCLUSION: Image quality, detailed morphology, and radiation dose, particularly in obese patients, were significantly improved in HRCT with PCCT compared to conventional EICT. The new technique enables visualization of subpleural structures.

Comparison of CBCT radiation doses with conventional radiographs in TMJ imaging using Monte Carlo simulations.

Three-dimensional imaging methods are widely used for evaluation of bony changes of temporomandibular joint (TMJ). Besides, lateral and posterio-anterior TMJ projections in both closed- and open-jaw positions for each temporomandibular joint are used as two-dimensional diagnostic tools. The purpose of the present study was to compare effective and mean organ absorbed doses of plain radiography techniques with those of different modalities of cone beam computed tomography (CBCT) scanning of an adult's temporomandibular joint. PCXMC 2.0 software was used to calculate mean organ and effective doses. A NewTom CBCT device (Newtom 5G XL; QR systems; Verona, Italy) was simulated at 360° rotation using a 6 × 6 cm2 FOV in standard and high-resolution modes. Lateral and posterio-anterior TMJ plain projections were simulated according to recommendations of the manufacturer of the Planmeca ProMax® 2D S3 device. Doses for both projections were simulated with Monte Carlo methods and the International Commission on radiological protection adult reference computational phantoms. The highest mean organ absorbed doses occurred in bone surfaces, salivary glands, and skull for posterio-anterior TMJ and lateral TMJ, and for CBCT scanning in all examinations. The effective doses of posterio-anterior and lateral TMJ plain radiographs were found to be higher than those of the Standard Mode-Eco Scan CBCT. Therefore, the lowest effective dose was calculated in Standard Mode-Eco Scan CBCT. It is concluded that NewTom 5G XL Standard Mode-Eco Scan CBCT can be used instead of plain radiographs (lateral and posterio-anterior TMJ) in temporomandibular joint imaging as it allows visualizing the three-dimensional structure of the temporomandibular joint as an advantage.

Impact of upgrading from a 25-cm to a 30-cm z-axis field of view digital PET/CT in a pediatric hospital.

BACKGROUND: Increased positron emission tomography (PET) scanner z-axis coverage provides an opportunity in pediatrics to reduce dose, anesthesia, or repeat scans due to motion. OBJECTIVE: Recently, our digital PET scanner was upgraded from a 25-cm to a 30-cm z-axis coverage. We compare the two systems through National Electrical Manufacturing Association (NEMA) testing and evaluation of paired images from patients scanned on both systems. MATERIALS AND METHODS: NEMA testing and a retrospective review of pediatric patients who underwent clinically indicated 18F-fluorodeoxyglucose (FDG) PET computed tomography (PET/CT) on both systems with unchanged acquisition parameters were performed. Image quality was assessed with liver signal to noise ratio (SNR-liver) and contrast to noise ratio (CNR) in the thigh muscle and liver with results compared with an unpaired t-test. Three readers independently reviewed paired (25 cm and 30 cm) images from the same patient, blinded to scanner configuration. RESULTS: Expansion to 30 cm increased system sensitivity to 29.8% (23.4 cps/kBq to 30.4 cps/kBq). Seventeen patients (6 male/11 female, median age 12.5 (IQR 8.3-15.0) years, median weight 53.7 (IQR 34.2-68.7) kg) were included. SNR-liver and CNR increased by 35.1% (IQR 19.0-48.4%) and 43.1% (IQR 6.2-50.2%) (P-value <0.001), respectively. All readers preferred images from the 30-cm configuration. A median of 1 (IQR 1-1) for fewer bed positions was required with the 30-cm configuration allowing a median of 91 (IQR 47-136) s for shorter scans. CONCLUSION: Increasing z-axis coverage from 25 to 30 cm on a current-generation digital PET scanner significantly improved PET system performance and patient image quality, and reduced scan duration.

The scientific nature of the linear no-threshold (LNT) model used in the system of radiological protection.

During the first half of the 20th century, it was commonly assumed that radiation-induced health effects occur only when the dose exceeds a certain threshold. This idea was discarded for stochastic effects when more knowledge was gained about the mechanisms of radiation-induced cancer. Currently, a key tenet of the international system of radiological protection is the linear no-threshold (LNT) model where the risk of radiation-induced cancer is believed to be directly proportional to the dose received, even at dose levels where the effects cannot be proven directly. The validity of the LNT approach has been questioned on the basis of a claim that only conclusions that can be verified experimentally or epidemiologically are scientific and LNT should, thus, be discarded because the system of radiological protection must be based on solid science. The aim of this publication is to demonstrate that the LNT concept can be tested in principle and fulfils the criteria of a scientific hypothesis. The fact that the system of radiological protection is also based on ethics does not render it unscientific either. One of the fundamental ethical concepts underlying the LNT model is the precautionary principle. We explain why it is the best approach, based on science and ethics (as well as practical experience), in situations of prevailing uncertainty.

X-ray Doses in Relation to Body Mass, Indication, and Substrate During Pediatric Electrophysiological Procedures on the Heart.

The main goal of this study is to determine typical values of dose area product (DAP) and difference in the effective dose (ED) for pediatric electrophysiological procedures on the heart in relation to patient body mass. This paper also shows DAP and ED in relation to the indication, the arrhythmia substrate determined during the procedure, and in relation to the reason for using radiation. Organ doses are described as well. The subjects were children who have had an electrophysiological study done with a 3D mapping system and X-rays in two healthcare institutions. Children with congenital heart defects were excluded. There were 347 children included. Significant difference was noted between mass groups, while heavier children had higher values of DAP and ED. Median DAP in different mass groups was between 4.00 (IQR 1.00-14.00) to 26.33 (IQR 8.77-140.84) cGycm2. ED median was between 23.18 (IQR 5.21-67.70) to 60.96 (IQR 20.64-394.04) µSv. The highest DAP and ED in relation to indication were noted for premature ventricular contractions and ventricular tachycardia-27.65 (IQR 12.91-75.0) cGycm2 and 100.73 (IQR 53.31-258.10) µSv, respectively. In arrhythmia substrate groups, results were similar, and the highest doses were in ventricular substrates with DAP 29.62 (IQR 13.81-76.0) cGycm2 and ED 103.15 (IQR 60.78-266.99) µSv. Pediatric electrophysiology can be done with very low doses of X-rays when using 3D mapping systems compared to X-rays-based electrophysiology, or when compared to pediatric interventional cardiology or adult electrophysiology.

Technical specifications of dose management systems: An international atomic energy agency survey.

PURPOSE: Dose management systems (DMS) have been introduced in radiological services to facilitate patient radiation dose management and optimization in medical imaging. The purpose of this study was to gather as much information as possible on the technical characteristics of DMS currently available, regarding features that may be considered essential for simply ensuring regulatory compliance or desirable to fully utilize the potential role of DMS in optimization of many aspects of radiological examinations. METHODS: A technical survey was carried out and all DMS developers currently available (both commercial and open source) were contacted and were asked to participate. An extensive questionnaire was prepared and uploaded in the IAEA International Research Integration System (IRIS) online platform which was used for data collection process. Most of the questions (93%) required a "Yes/No" answer, to facilitate an objective analysis of the survey results. Some free text questions and comments' slots were also included, to allow participants to give additional information and clarifications where necessary. Depending on the answer, they were considered either as "Yes" or "No." RESULTS: Given the way that the questions were posed, every positive response indicated that a feature was offered. Thus, the percentage of positive responses was used as a measure of adherence. The percentages of positive answers per section (and sub-section) are presented in graphs and limitations of this type of analysis are discussed in detail. CONCLUSIONS: The results of this survey clearly exhibit that large differences exist between the various DMS developers. Consequently, potential end users of a DMS should carefully determine which of the features available are essential for their needs, prioritize desirable features, but also consider their infrastructure, the level of support required and the budget available before selecting a DMS.

CT image denoising methods for image quality improvement and radiation dose reduction.

With the ever-increasing use of computed tomography (CT), concerns about its radiation dose have become a significant public issue. To address the need for radiation dose reduction, CT denoising methods have been widely investigated and applied in low-dose CT images. Numerous noise reduction algorithms have emerged, such as iterative reconstruction and most recently, deep learning (DL)-based approaches. Given the rapid advancements in Artificial Intelligence techniques, we recognize the need for a comprehensive review that emphasizes the most recently developed methods. Hence, we have performed a thorough analysis of existing literature to provide such a review. Beyond directly comparing the performance, we focus on pivotal aspects, including model training, validation, testing, generalizability, vulnerability, and evaluation methods. This review is expected to raise awareness of the various facets involved in CT image denoising and the specific challenges in developing DL-based models.

Machine learning-based estimation of patient body weight from radiation dose metrics in computed tomography.

PURPOSE: Currently, precise patient body weight (BW) at the time of diagnostic imaging cannot always be used for radiation dose management. Various methods have been explored to address this issue, including the application of deep learning to medical imaging and BW estimation using scan parameters. This study develops and evaluates machine learning-based BW prediction models using 11 features related to radiation dose obtained from computed tomography (CT) scans. METHODS: A dataset was obtained from 3996 patients who underwent positron emission tomography CT scans, and training and test sets were established. Dose metrics and descriptive data were automatically calculated from the CT images or obtained from Digital Imaging and Communications in Medicine metadata. Seven machine-learning models and three simple regression models were employed to predict BW using features such as effective diameter (ED), water equivalent diameter (WED), and mean milliampere-seconds. The mean absolute error (MAE) and correlation coefficient between the estimated BW and the actual BW obtained from each BW prediction model were calculated. RESULTS: Our results found that the highest accuracy was obtained using a light gradient-boosting machine model, which had an MAE of 1.99 kg and a strong positive correlation between estimated and actual BW (ρ = 0.972). The model demonstrated significant predictive power, with 73% of patients falling within a ±5% error range. WED emerged as the most relevant dose metric for BW estimation, followed by ED and sex. CONCLUSIONS: The proposed machine-learning approach is superior to existing methods, with high accuracy and applicability to radiation dose management. The model's reliance on universal dose metrics that are accessible through radiation dose management software enhances its practicality. In conclusion, this study presents a robust approach for BW estimation based on CT imaging that can potentially improve radiation dose management practices in clinical settings.

Preoperative Planning for Shoulder Arthroplasty is Feasible with Computed Tomography at Lower-Than-Conventional Radiation Doses.

INTRODUCTION: Computed tomography (CT) offers a detailed assessment of the shoulder for preoperative shoulder arthroplasty planning; however, this technique exposes the patient to ionizing radiation. The purpose of this study was to prospectively evaluate the practicality of reducing the CT radiation dose compared to conventional dose levels for manual and preoperative planning software measurements for shoulder arthroplasty. METHODS: A total of 10 shoulder CT examinations were performed for preoperative planning purposes on a dual x-ray source CT scanner. A specialized dose-split scan technique was utilized to reconstruct CT images corresponding to 100%, 70%, and 30% radiation dose relative to our institution's standard of care imaging protocol. Glenoid version, inclination, and humeral head subluxation were measured manually by three authors and by commercially available software platforms. These measurements were analyzed for agreement between the 100%, 70%, and 30% dose levels for each patient. Tolerances of 5° of glenoid version, 5° of glenoid inclination, and 10% humeral head subluxation were used as equivalent for preoperative planning. RESULTS: Automated measurements of 70% dose images were within 5° of version, 5° of inclination, and 10% subluxation in 95.0% of cases. Manual measurements of 70% RD images were within 5° of version for 90.0% of cases, 5° of inclination in 86.7% of cases, and 10% subluxation in 100% of cases. Automated measurements from the 30% dose images were within 5° of version, 5° of inclination, and 10% subluxation for 100% of cases. Manual measurements from the 30% dose images were within 5° of version for 86.7% of cases, 5° of inclination in 76.7% of cases, and 10% subluxation in 100% of cases. The mean absolute difference in software measurement of glenoid version (p = 0.96), glenoid inclination (p = 0.64), or humeral head subluxation (p = 0.09) or in aggregated manual mean absolute difference of version (p = 0.22), inclination (p = 0.31), or humeral head subluxation (p = 0.56) was not significant. Good to excellent reliability was determined by interclass correlation coefficients among the manual observers and automatic software platforms for measurements at all doses (P<0.001) CONCLUSIONS: The results indicate that both preoperative planning software platforms and human observers produced similar measurements of glenoid version, inclination, and humeral head subluxation from reduced-dose images compared to standard of care doses. By implementing reduced dose techniques in preoperative shoulder CT, the potential risks associated with radiation exposure could be reduced for patients undergoing shoulder arthroplasty.

Factors affecting radiation dose, radiation exposure time and procedural time in arterial embolization for active hemorrhage.

PURPOSE: To evaluate patient and procedure-related factors contributing to the radiation dose, cumulative fluoroscopy time (CFT), and procedural time (PT) of Arterial Embolization (AE) for suspected active bleeding. METHODS: Data on patients who underwent AE for suspected bleeding was retrospectively gathered between January 2019 and April 2022. Data collected included the dependent variables consisting of dose-area product (DAP), CFT, PT, and independent variables consisting of demographic, bleeding-specific, and procedure-specific parameters. All statistical computations were performed in SPSS statistics. The alpha value was set at 0.05. RESULTS: Data from a total of 148 AE were collected with an average patient's age of 61.06 ± 21.57 years. Higher DAP was independently associated with male sex (p < 0.002), age ranges between 46 and 65 years (p = 0.019) and > 66 years (p = 0.027), BMI above 30 (p = 0.016), attending with less than 10 years of experience (p = 0.01), and bleeding in the abdomen and pelvis (p = 0.027). Longer CFT was independently associated with attending with less than 10 years of experience (p < 0.001), having 2 (p = 0.004) or > 3 (p = 0.005) foci of bleed, and age between 46 and 65 years (p = 0.007) and ≥ 66 years (p = 0.017). Longer PT was independently associated with attending with less than 10 years of experience (p < 0.001) and having 2 (p = 0.014) or > 3 (p = 0.005) foci of bleed. CONCLUSION: The interventionist experience influenced radiation dose, CFT and PT. Dose was also affected by patients' sex, age, BMI, as well as bleeding location. CFT was also affected by patients' age, and both CFT and PT were also affected by the number of bleeding foci. These findings highlight the multifaceted factors that affect radiation dose and procedural time, emphasizing the importance of interventionist expertise, patient's age, sex, BMI, location and number of bleeds.

XMEA: A New Hybrid Diamond Multielectrode Array for the In Situ Assessment of the Radiation Dose Enhancement by Nanoparticles.

This work presents a novel multielectrode array (MEA) to quantitatively assess the dose enhancement factor (DEF) produced in a medium by embedded nanoparticles. The MEA has 16 nanocrystalline diamond electrodes (in a cell-culture well), and a single-crystal diamond divided into four quadrants for X-ray dosimetry. DEF was assessed in water solutions with up to a 1000 µg/mL concentration of silver, platinum, and gold nanoparticles. The X-ray detectors showed a linear response to radiation dose (r2 ≥ 0.9999). Overall, platinum and gold nanoparticles produced a dose enhancement in the medium (maximum of 1.9 and 3.1, respectively), while silver nanoparticles produced a shielding effect (maximum of 37%), lowering the dose in the medium. This work shows that the novel MEA can be a useful tool in the quantitative assessment of radiation dose enhancement due to nanoparticles. Together with its suitability for cells' exocytosis studies, it proves to be a highly versatile device for several applications.