Radiation Dose Levels Research Articles

An Image Quality-informed Framework for CT Characterization.

Background Lack of standardization in CT protocol choice contributes to radiation dose variation. Purpose To create a framework to assess radiation doses within broad CT categories defined according to body region and clinical imaging indication and to cluster indications according to the dose required for sufficient image quality. Materials and Methods This was a retrospective study using Digital Imaging and Communications in Medicine metadata. CT examinations in adults from January 1, 2016 to December 31, 2019 from the University of California San Francisco International CT Dose Registry were grouped into 19 categories according to body region and required radiation dose levels. Five body regions had a single dose range (ie, extremities, neck, thoracolumbar spine, combined chest and abdomen, and combined thoracolumbar spine). Five additional regions were subdivided according to dose. Head, chest, cardiac, and abdomen each had low, routine, and high dose categories; combined head and neck had routine and high dose categories. For each category, the median and 75th percentile (ie, diagnostic reference level [DRL]) were determined for dose-length product, and the variation in dose within categories versus across categories was calculated and compared using an analysis of variance. Relative median and DRL (95% CI) doses comparing high dose versus low dose categories were calculated. Results Among 4.5 million examinations, the median and DRL doses varied approximately 10 times between categories compared with between indications within categories. For head, chest, abdomen, and cardiac (3 266 546 examinations [72%]), the relative median doses were higher in examinations assigned to the high dose categories than in examinations assigned to the low dose categories, suggesting the assignment of indications to the broad categories is valid (head, 3.4-fold higher [95% CI: 3.4, 3.5]; chest, 9.6 [95% CI: 9.3, 10.0]; abdomen, 2.4 [95% CI: 2.4, 2.5]; and cardiac, 18.1 [95% CI: 17.7, 18.6]). Results were similar for DRL doses (all P < .001). Conclusion Broad categories based on image quality requirements are a suitable framework for simplifying radiation dose assessment, according to expected variation between and within categories. © RSNA, 2021 See also the editorial by Mahesh in this issue.

Irradiation influence on the chemical composition and morphological properties of the agricultural products

The article discusses the impact of radiation treatment of agricultural products on their chemical composition, which determines the nutritional value of products, as well as on the main properties of products. The main advantages of agricultural products that have undergone radiation treatment are given, related, inter alia, to an increase in their shelf life, prevention of diseases and insect damage. The world experience of increasing the volume of radiation processing products by type in comparison with the 2010 level is considered. The main criteria for radiation processing of food products and the levels of radiation doses required for absorption by products to achieve certain technological goals are presented. The influence of radiation doses of radiation on proteins, fats, carbohydrates and vitamins in agricultural products is indicated. The influence of radiation exposure on the growth and maturation of some crops is estimated. The possibility of the influence of changes in the structure and composition of irradiated food products on the human body is emphasized. The factors that ensure the profitability of farms that use the practice of radiation processing of agricultural products when supplying them to international markets are also given. The calculations are carried out on a model of a small farm specializing in the cultivation of cucumbers and tomatoes.

A Novel Approach to Dose De-Escalation in HPV-Positive Oropharyngeal Chemoradiotherapy Utilizing Adaptive Planning Based on Voxel-Level FDG Response

Definitive chemoradiation for HPV-positive oropharyngeal squamous cell carcinoma (HPV+ OPC) is associated with high cure rates, but also with significant patient morbidity. Using previously described techniques to create heterogenous radiotherapy dose level selection, combined with data from patients followed by serial FDG-PET/CT during definitive chemoradiation, we generated hypothetical adaptive radiation plans with the goal of decreasing dose to normal tissues while maintaining equivalent local control.Five patients with HPV+ OPC enrolled on a prospective single-institution protocol with serial FDG-PET/CT imaging during the course of definitive chemoradiation were analyzed. Two radiotherapy plans were then generated for each patient: one in which gross disease was prescribed a uniform dose of 60 Gy, and a second using adaptive tumor response to progressively reduce the prescription dose to gross disease in a heterogenous fashion. Voxel-level changes in FDG avidity were combined with a previously described tumor voxel control probability model to guide dose de-escalation in radiosensitive regions of tumor while maintaining equivalent local control. Dose accumulation to nearby organs at risk (OARs), incorporating changes due to progressive de-escalation, were then compared for the two sets of plans using the paired samples Wilcoxon test.The de-escalated plans created using voxel-level tumor response resulted in treatment plans with significantly reduced dose to all evaluated OARs. Significant improvements included a decreased spinal cord maximum dose, brainstem maximum dose, parotoid gland mean dose, constrictor muscle mean and maximum dose, and mandible maximum dose (P = 0.03). Projected tumor control probability remained high, despite de-escalation of dose in PET-sensitive areas of gross disease.Adaptive FDG-PET response can be used to guide de-escalation to reduce dose to nearby OARs. Using a novel technique for dose selection based on voxel-level tumor response, heterogeneous de-escalation can further reduce toxicity while maintaining optimal local control in most patients with HPV+ OPC. This concept will be used to design a non-randomized prospective trial investigating the role of heterogeneous de-escalation in this patient population.

Comparison of Clinical Efficacy of Neoadjuvant Chemoradiation Therapy Between Lower and Higher Radiation Doses for Carcinoma of the Esophagus and Gastroesophageal Junction: A Systematic Review

<h3>Purpose</h3> Neoadjuvant concurrent chemoradiation therapy (nCRT) plus surgery has been a standard treatment for locoregionally advanced esophageal cancer and carcinoma of the gastroesophageal junction (EC/GEJ), but the optimal preoperative radiation dose is still unclear. We performed this systematic review to explore the treatment efficacy and toxicity of different radiation dose levels and find an optimal dose‐fractionation strategy in EC/GEJ patients receiving nCRT. <h3>Methods and Materials</h3> Embase and Ovid Medline were searched for articles involving cases of operable squamous and adenocarcinoma of the esophagus and GEJ in which patients received nCRT up to a dose of 50.4 Gy in 28 fractions that were published until July 2019, when the search was performed. Physical dose distributions were converted to biologically equivalent doses (BEDs), which were described in units of gray (alpha/beta). Pooled rates of overall survival (OS), progression-free survival (PFS), failure patterns, and toxicities were compared between lower-dose radiation therapy (LDRT; BED ≤48.85 Gy₁₀) and higher-dose radiation therapy (HDRT; BED >48.85 Gy₁₀) for patients treated with nCRT. <h3>Results</h3> A total of 110 studies with 7577 EC/GEJ patients receiving nCRT were included in this pooled analysis. Both the PFS and OS rates of patients receiving LDRT were significantly higher than those of patients receiving HDRT. Patients receiving LDRT had improved safety regarding treatment-related adverse events and lower distant failure rates than patients receiving HDRT. Utilization of modern radiation therapy (RT) techniques, including 3-dimensional conformal RT and intensity modulated RT, was associated with improved oncologic outcomes compared with 2-dimensional methods. Subgroup analysis showed that EC/GEJ patients receiving conventionally fractionated radiation to a dose of 40.0 to 41.4 Gy in 20-23 fractions showed improved OS compared with those receiving radiation above this dose. <h3>Conclusions</h3> Based on the limited data, nCRT using BED ≤48.85 Gy₁₀ was suitable for locoregionally advanced, resectable EC/GEJ. A total dose of 40.0 to 41.4 Gy in 20 to 23 fractions using modern RT techniques might provide the optimal therapeutic ratio.

Comparison of patient and staff temple dose during fluoroscopically guided coronary angiography, implantable cardiac devices, and electrophysiology procedures.

There is a paucity of literature comparing patient and staff dose during coronary angiography (CA), implantable cardiac devices, permanent pacemakers (PPM) and electrophysiology (EP) procedures and little noting dose to staff other than cardiologists. This study sought to compare patient and occupational dose during a range of fluoroscopically guided cardiac procedures. Radiation dose levels for the patients (n=1651), cardiologists (n=24), scrub (n=32) and scout nurses (n=35) were measured in a prospective single-centre study between February 2017 and August 2019. A comparison of dose during CA, device implantation, PPM insertion and EP studies was performed. Three angiographic units were used, with dosimeters worn on the temple of staff. Results indicated that occupational dose during PPM was significantly higher than other procedures. The cardiologist had the highest mean dose during biventricular implantable cardioverter-defibrillators; levels were approximately five times that of 'normal' pacemaker insertions. Transcatheter aortic valve implantations (TAVI) were associated with relatively high mean doses for both staff and patients and had a statistically significant higher (>2 times) mean patient dose area product than all other categories. TAVI workups were also related to higher mean cardiologist and scrub nurse dose. It was observed that the mean scrub nurse dose can exceed that of the cardiologist. The highest mean dose for Scout nurses were recorded during EP studies. Given the significantly higher temple dose associated with PPM insertion, cardiologists should consider utilizing ceiling mounted lead shields, lead glasses and/or skull caps where possible. Efforts should also be made to minimize the use of DSA during TAVI and TAVI workups to reduce cardiologist, nurse and patient dose.

Establishing a diagnostic reference level of radiation dose in coronary angiography and intervention: A prospective evaluation

IntroductionInvasive Coronary Angiography (CAG) leads to significant radiation exposure to the patients. Guidelines suggest that a local landmark or Diagnostic Reference Level (DRL) for these procedures should be established for every region and country. This study attempts to create a DRL for a tertiary care hospital, acting as an interim DRL for the country/region. MethodsRadiation exposure data for all coronary procedures done at a tertiary care hospital between October 2016 to September 2018 were collected. Data was segregated into diagnostic Coronary Angiography (CAG) and single-vessel Percutaneous Intervention (PCI). The parameters collected include dose surface product (PKA), skin surface entry dose (KAR), and fluoroscopy time (FT). The 75th percentile of the PKA was used to define the DRL. Results500 Patients were included in the CAG group, in which the Median KAR was 412.05 mGy, Median PKA was 2635.7 μGysqm, and median FT was 2.25 min. The DRL for coronary angiography was calculated as 3695.1 μGysqm. Two hundred fifty patients were in the PCI group, the Median KAR was 1649 mGy, Median PKA was 8822.1 μGysqm, the median FT being 8.2 min. The DRL for single-vessel coronary intervention was calculated as 11038 μGysqm. ConclusionThis study establishes a benchmark for radiation dose for diagnostic coronary angiography and single-vessel coronary intervention at a tertiary care hospital in NCR. It establishes an interim DRL that can be used for future studies in other institutions in the region and country and to compare with other countries.

Coronary Calcium Scoring with First Generation Dual-Source Photon-Counting CT-First Evidence from Phantom and In-Vivo Scans.

We evaluated the accuracy of coronary artery calcium (CAC) scoring on a dual-source photon-counting detector CT (PCD-CT). An anthropomorphic chest phantom underwent ECG-gated sequential scanning on a PCD-CT at 120 kV with four radiation dose levels (CTDIvol, 2.0–8.6 mGy). Polychromatic images at 120 kV (T3D) and virtual monoenergetic images (VMI), from 60 to 75 keV without quantum iterative reconstruction (no QIR) and QIR strength levels 1–4, were reconstructed. For reference, the same phantom was scanned on a conventional energy-integrating detector CT (120 kV; filtered back projection) at identical radiation doses. CAC scoring in 20 patients with PCD-CT (120 kV; no QIR and QIR 1–4) were included. In the phantom, there were no differences between CAC scores of different radiation doses (all, p > 0.05). Images with 70 keV, no QIR (CAC score, 649); 65 keV, QIR 3 (656); 65 keV; QIR4 (648) and T3D, QIR4 (656) showed a <1% deviation to the reference (653). CAC scores significantly decreased at increasing QIR levels (all, p < 0.001) and for each 5 keV-increase (all, p < 0.001). Patient data (median CAC score: 86 [inter-quartile range: 38–978] at 70 keV) confirmed relationships and differences between reconstructions from the phantom. First phantom and in-vivo experience with a clinical dual-source PCD-CT system shows accurate CAC scoring with VMI reconstructions at different radiation dose levels.

Assessment of dentists' knowledge and practice regarding the principles of protection against ionizing radiation

Background: Today, the use of dental radiography equipment in dental centers has increased due to its high application in the diagnosis of dental diseases. As a result, concerns are increasing regarding repeated exposure to this low dose level of radiation. Therefore, the knowledge and practice of dentists about radiation protection are essential for themselves and the patients. This study aimed to assess the knowledge and practice of dentists about radiation protection. Materials and Methods: This cross-sectional study was performed based on a questionnaire in several cities of Iran. The first part of the questionnaire included such information as gender, years of work experience, and participation in radiation protection workshops. The second, third, and fourth sections consisted of questions on radiobiology, radiation protection, and performance, respectively. Results: In this study, 94 dentists participated, and the mean scores of dentists (out of 5 points) for radiobiology knowledge, radiation protection knowledge, and performance were obtained at 2.66±1.1, 2.80±1.01, and 2.87±1.37, respectively. The results of Pearson analysis showed that general knowledge had a significant relationship with performance (P=0.014). There was also a significant relationship between the history of participation in radiation protection workshops and performance (P=0.01). Conclusion: It was found that more knowledge about the effects of ionizing radiation on the body and more awareness of the principles of radiation protection would help dentists to better observe the practical principles of radiation protection. Also, participating in radiation protection workshops could increase dentists' knowledge, and therefore, improve their performance.

Optimization of cone beam computed tomography for the assessment of alterations of the maxillary sinuses

Objective: To test the standard protocols of a CBCT unit in order to find lower-dose alternatives with diagnostically acceptable image quality for the maxillary sinuses visualization. Study design: An observational study was performed. Two dry skulls were used to simulate four conditions of the maxillary sinuses: normality, mucous retention pseudocyst, membrane thickening and bone graft. Cone beam computed tomography scans were obtained with an i-CAT classic unit using different acquisition protocols and a box of polystyrene to simulate soft tissue attenuation. All the protocols were established by the manufacturer, combining different energy parameters, fields of view and voxel sizes. Multiplanar reconstructions were presented to three Oral Radiologists through blind and randomized distribution. The specialists judged general image quality, sharpness, contrast, and the presence of noise and artifacts based on a 4-points scale. Results: Protocols with higher energy parameters had significant association with higher scores for general quality, sharpness and contrast (p&lt;0.05). Protocols with intermediate level of radiation dose had also significant association with good and excellent image quality; for the presence of noise and artifacts the images were rated acceptable. Conclusion: i-CAT default protocols with lower dose of radiation were able to deliver acceptable image quality for the visualization of the maxillary sinuses.

Personalized Chest Computed Tomography: Minimum Diagnostic Radiation Dose Levels for the Detection of Fibrosis, Nodules, and Pneumonia.

ObjectivesThe purpose of this study was to evaluate the minimum diagnostic radiation dose level for the detection of high-resolution (HR) lung structures, pulmonary nodules (PNs), and infectious diseases (IDs).Materials and MethodsA preclinical chest computed tomography (CT) trial was performed with a human cadaver without known lung disease with incremental radiation dose using tin filter-based spectral shaping protocols. A subset of protocols for full diagnostic evaluation of HR, PN, and ID structures was translated to clinical routine. Also, a minimum diagnostic radiation dose protocol was defined (MIN). These protocols were prospectively applied over 5 months in the clinical routine under consideration of the individual clinical indication. We compared radiation dose parameters, objective and subjective image quality (IQ).ResultsThe HR protocol was performed in 38 patients (43%), PN in 21 patients (24%), ID in 20 patients (23%), and MIN in 9 patients (10%). Radiation dose differed significantly among HR, PN, and ID (5.4, 1.2, and 0.6 mGy, respectively; P < 0.001). Differences between ID and MIN (0.2 mGy) were not significant (P = 0.262). Dose-normalized contrast-to-noise ratio was comparable among all groups (P = 0.087). Overall IQ was perfect for the HR protocol (median, 5.0) and decreased for PN (4.5), ID-CT (4.3), and MIN-CT (2.5). The delineation of disease-specific findings was high in all dedicated protocols (HR, 5.0; PN, 5.0; ID, 4.5). The MIN protocol had borderline IQ for PN and ID lesions but was insufficient for HR structures. The dose reductions were 78% (PN), 89% (ID), and 97% (MIN) compared with the HR protocols.ConclusionsPersonalized chest CT tailored to the clinical indications leads to substantial dose reduction without reducing interpretability. More than 50% of patients can benefit from such individual adaptation in a clinical routine setting. Personalized radiation dose adjustments with validated diagnostic IQ are especially preferable for evaluating ID and PN lesions.

CT Noise-Reduction Methods for Lower-Dose Scanning: Strengths and Weaknesses of Iterative Reconstruction Algorithms and New Techniques.

Iterative reconstruction (IR) algorithms are the most widely used CT noise-reduction method to improve image quality and have greatly facilitated radiation dose reduction within the radiology community. Various IR methods have different strengths and limitations. Because IR algorithms are typically nonlinear, they can modify spatial resolution and image noise texture in different regions of the CT image; hence traditional image-quality metrics are not appropriate to assess the ability of IR to preserve diagnostic accuracy, especially for low-contrast diagnostic tasks. In this review, the authors highlight emerging IR algorithms and CT noise-reduction techniques and summarize how these techniques can be evaluated to help determine the appropriate radiation dose levels for different diagnostic tasks in CT. In addition to advanced IR techniques, we describe novel CT noise-reduction methods based on convolutional neural networks (CNNs). CNN-based noise-reduction techniques may offer the ability to reduce image noise while maintaining high levels of image detail but may have unique drawbacks. Other novel CT noise-reduction methods are being developed to leverage spatial and/or spectral redundancy in multiphase or multienergy CT. Radiologists and medical physicists should be familiar with these different alternatives to adapt available CT technology for different diagnostic tasks. The scope of this article is (a) to review the clinical applications of IR algorithms as well as their strengths, weaknesses, and methods of assessment and (b) to explore new CT image reconstruction and noise-reduction techniques that promise to facilitate radiation dose reduction. ©RSNA, 2021.

Modeling of the ambient radiation dose level by using passive moss biomonitoring in Macedonia

Modeling of the ambient radiation dose level by using passive moss biomonitoring in Macedonia

Dose reduction potential of vendor-agnostic deep learning model in comparison with deep learning-based image reconstruction algorithm on CT: a phantom study.

ObjectivesTo compare the dose reduction potential (DRP) of a vendor-agnostic deep learning model (DLM, ClariCT.AI) with that of a vendor-specific deep learning–based image reconstruction algorithm (DLR, TrueFidelity™).MethodsComputed tomography (CT) images of a multi-sized image quality phantom (Mercury v4.0) were acquired under six radiation dose levels (0.48/0.97/1.93/3.87/7.74/15.47 mGy) and were reconstructed using filtered back projection (FBP) and three strength levels of the DLR (low/medium/high). The FBP images were denoised using the DLM. For all DLM and DLR images, the detectability index (d′) (a task-based detection performance metric) was obtained, under various combinations of three target sizes (10/5/1 mm), five inlets (CT value difference with the background; −895/50/90/335/1000 HU), five phantom diameters (36/31/26/21/16 cm), and six radiation dose levels. Dose reduction potential (DRP) measures the dose reduction made by using DLM or DLR, while yielding d′ equivalent to that of FBP at full dose.ResultsThe DRPs of the DLM, DLR-low, DLR-medium, and DLR-high were 86% (81–88%), 60% (46–67%), 76% (60–81%), and 87% (78–92%), respectively. For 10-mm targets, the DRP of the DLM (87%) was higher than that of all DLR algorithms (58–86%). However, for smaller targets (5 mm/1 mm), the DRPs of the DLR-high (89/88%) were greater than those of the DLM (87/84%).ConclusionThe dose reduction potential of the vendor-agnostic DLM was shown to be comparable to that of the vendor-specific DLR at high strength and superior to those of the DLRs at medium and low strengths.Key Points• DRP of the vendor-agnostic model was comparable to that of high-strength vendor-specific model and superior to those of medium- and low-strength models.• Under various radiation dose levels, the deep learning model shows higher detectability indexes compared to FBP.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00330-021-08199-9.

Advanced image guidance for prostatic artery embolization \u2013 a multicenter technical note

BackgroundProstatic artery embolization (PAE) is associated with patients’ quality of life improvements and limited side effects compared to surgery. However, this procedure remains technically challenging due to complex vasculature, anatomical variations and small arteries, inducing long procedure times and high radiation exposure levels both to patients and medical staff. Moreover, the risk of non-target embolization can lead to relevant complications. In this context, advanced imaging can constitute a solid ally to address these challenges and deliver good clinical outcomes at acceptable radiation levels.Main textThis technical note aims to share the consolidated experience of four institutions detailing their optimized workflow using advanced image guidance, discussing variants, and sharing their best practices to reach a consensus standardized imaging workflow for PAE procedure, as well as pre and post-operative imaging.ConclusionsThis technical note puts forth a consensus optimized imaging workflow and best practices, with the hope of helping drive adoption of the procedure, deliver good clinical outcomes, and minimize radiation dose levels and contrast media injections while making PAE procedures shorter and safer.

Radiation dose levels in chest computed tomography scans of coronavirus disease 2019 pneumonia: A survey of 2119 patients in Chongqing, southwest China.

To investigate computed tomography (CT) diagnostic reference levels for coronavirus disease 2019 (COVID-19) pneumonia by collecting radiation exposure parameters of the most performed chest CT examinations and emphasize the necessity of low-dose CT in COVID-19 and its significance in radioprotection.The survey collected RIS data from 2119 chest CT examinations for 550 COVID-19 patients performed in 92 hospitals from January 23, 2020 to May 1, 2020. Dose data such as volume computed tomography dose index, dose-length product, and effective dose (ED) were recorded and analyzed. The radiation dose levels in different hospitals have been compared, and average ED and cumulative ED have been studied.The median dose-length product, volume computed tomography dose index, and ED measurements were 325.2 mGy cm with a range of 6.79 to 1098 mGy cm, 9.68 mGy with a range of 0.62 to 33.80 mGy, and 4.55 mSv with a range of 0.11 to 15.37 mSv for COVID-19 CT scanning protocols in Chongqing, China. The distribution of all observed EDs of radiation received by per patient undergoing CT protocols during hospitalization yielded a median cumulative ED of 17.34 mSv (range, 2.05–53.39 mSv) in the detection and management of COVID-19 patients. The average number of CT scan times for each patient was 4.0 ± 2.0, and the average time interval between 2 CT scans was 7.0 ± 5.0 days. The average cumulative ED of chest CT examinations for COVID-19 patients in Chongqing, China greatly exceeded public limit and the annual dose limit of occupational exposure in a short period.For patients with known or suspected COVID-19, a chest CT should be performed on the principle of rapid-scan, low-dose, single-phase protocol instead of routine chest CT protocol to minimize radiation doses and motion artifacts.

The Use of Cone Beam CT in Dental, Oral, and Maxillofacial Surgery, and Otolaryngology Settings

&#x0D; The objective of this Environmental Scan was to determine how cone beam CT (CBCT) is being used in Canada, to identify the types of professionals conducting CBCT exams, and to identify the training requirements for CBCT operators.&#x0D; This scan was informed by a literature search and survey of a sample representation from various clinical settings across Canada. Survey responses were received from Ontario, British Columbia, Manitoba, Prince Edward Island, and Alberta. More than a third of responses were received from dentists in Ontario.&#x0D; Ionizing radiation has been shown to be a risk factor for the development of malignancy. Since CBCT delivers a higher dose of radiation compared to conventional 2-D imaging, it is important to ensure that the level of exposure to radiation is as low as possible.&#x0D; Based on responses from the survey, CBCT scans appear to be most commonly being used for dental implantology planning in adults. CBCT also appears to be commonly used for detection of impacted teeth, detection of oral and facial cysts, tumours, and endodontic imaging in adults.&#x0D; Survey feedback suggests that CBCT is rarely used in children, who are the most sensitive to the effects of ionizing radiation. With the exception of 1 respondent, survey feedback suggested that CBCT is not typically being used for infants and children younger than the age of 5. Respondents rarely used CBCT for children aged 5 to 9 years. The most common procedures used in children 5 years to 17 years of age appear to be for the detection of impacted teeth and the detection of oral and facial cysts, and tumours.&#x0D; Across all age groups, respondents rarely used CBCT for caries (tooth decay) detection, gum disease detection, nasal septum imaging, and cleft palate imaging. No respondents reported using CBCT for plastic surgery, inner ear imaging, or skull and cranial imaging; however, this may be because of the responses being primarily from dentists.&#x0D; A wide range of radiation dose levels associated with CBCT use were reported in the survey, depending on the age group, specific procedure, and the radiation dose metric used.&#x0D; Educational provisions in place for CBCT operators to ensure safety and technical competence differs between the provinces, with some taking more structured approaches than others. The health professionals allowed to operate CBCT scanners also vary between provinces. Based on the survey results, dentists made up the bulk of health professionals currently conducting CBCT scans; however, dentists were also the most well-represented among survey respondents, which may have influenced this result.&#x0D; Several CBCT scanner models are currently being used in Canada. Most respondents indicated that CBCT scanners have imaging pre-sets that they use for the procedures they perform. Approximately half of respondents indicated that they have also defined their own imaging parameters for some procedures. Most of the CBCT systems being used include exposure tables, which the majority of respondents found easy to understand.&#x0D;

Fully automated whole-liver volume quantification on CT-image data: Comparison with manual volumetry using enhanced and unenhanced images as well as two different radiation dose levels and two reconstruction kernels.

ObjectivesTo evaluate the accuracy of fully automated liver volume quantification vs. manual quantification using unenhanced as well as enhanced CT-image data as well as two different radiation dose levels and also two image reconstruction kernels.Material and methodsThe local ethics board gave its approval for retrospective data analysis. Automated liver volume quantification in 300 consecutive livers in 164 male and 103 female oncologic patients (64±12y) performed at our institution (between January 2020 and May 2020) using two different dual-energy helicals: portal-venous phase enhanced, ref. tube current 300mAs (CARE Dose4D) for tube A (100 kV) and ref. 232mAs tube current for tube B (Sn140kV), slice collimation 0.6mm, reconstruction kernel I30f/1, recon. thickness of 0.6mm and 5mm, 80–100 mL iodine contrast agent 350 mg/mL, (flow 2mL/s) and unenhanced ref. tube current 100mAs (CARE Dose4D) for tube A (100 kV) and ref. 77mAs tube current for tube B (Sn140kV), slice collimation 0.6mm (kernel Q40f) were analyzed. The post-processing tool (syngo.CT Liver Analysis) is already FDA-approved. Two resident radiologists with no and 1-year CT-experience performed both the automated measurements independently from each other. Results were compared with those of manual liver volume quantification using the same software which was supervised by a senior radiologist with 30-year CT-experience (ground truth).ResultsIn total, a correlation of 98% was obtained for liver volumetry based on enhanced and unenhanced data sets compared to the manual liver quantification. Radiologist #1 and #2 achieved an inter-reader agreement of 99.8% for manual liver segmentation (p<0.0001). Automated liver volumetry resulted in an overestimation (>5% deviation) of 3.7% for unenhanced CT-image data and 4.0% for contrast-enhanced CT-images. Underestimation (<5%) of liver volume was 2.0% for unenhanced CT-image data and 1.3% for enhanced images after automated liver volumetry. Number and distribution of erroneous volume measurements using either thin or thick slice reconstructions was exactly the same, both for the enhanced as well for the unenhanced image data sets (p> 0.05).ConclusionResults of fully automated liver volume quantification are accurate and comparable with those of manual liver volume quantification and the technique seems to be confident even if unenhanced lower-dose CT image data is used.

STATUS OF RADIATION DOSE LEVELS IN PAEDIATRIC CHEST RADIOGRAPHY IN A TERTIARY HOSPITAL IN GHANA.

Determination of appropriate radiation doses to paediatric patients in accordance with the as low as reasonably achievable (ALARA) principle is important, as it allows for effective optimization of imaging techniques. This study assessed the status of radiation dose levels in paediatric patients undergoing chest X-ray examinations at a tertiary hospital in Ghana. A population encompassing 86 paediatric patients categorised as infants (<1y), young children (1-5y) and older children (6-12y) was selected using a quasi-experimental study design. The patients' anatomical data and X-ray beam exposure parameters were used to indirectly calculate the entrance surface doses (ESDs) received during the examinations. The infants received the highest mean ESD of 196 μGy (uncertainty=0.37) compared to 158 μGy (uncertainty=0.46) among the older children. The risk of developing radiation-induced biological effects was therefore higher for infant patients. The ESDs were generally higher than the internationally recommended reference doses. Careful adoption of internationally accepted exposure factors (high tube voltage and low tube load) is most recommended to optimise the dose.

Determination of the Last Semester Radiology Technology Students’ Knowledge About Radiation Protection, Radiation Exposure and Cancer Risk of Diagnostic Examinations With Lonizing Radiation

Background and Objectives: Radiology technicians have a critical role in protecting patients along with providing high-quality images. The present study assessed radiology students' last semester about the principles of protection, dose level, and cancer risk of ionizing radiation applied for diagnostic imaging. This study was conducted in training hospitals of Ahvaz Jundishapur University of Medical Sciences, Ahvaz City, Iran. Subjects and Methods This cross-sectional descriptive study was performed using a study-designed questionnaire. The sample size was 40, and statistical analysis was performed in SPSS v. 24. Results Only 15% of students correctly answered the question of ionizing radiation stochastic effect. While 70% of students stated the average dose of an abdominal ultrasound correctly, only 2.5% of them determined the average dose of a myocardial nuclear medicine scan correctly. In total, the respondents received 35% of the overall score of knowledge about cancer risk caused by ionizing radiation of imaging examinations. Conclusion The students' knowledge about the principles of radiation protection was moderate, and their knowledge about the level of radiation dose and cancer risk caused by various imaging procedures was insufficient. Theoretical and practical education has a significant role in improving the knowledge and skills of radiology technicians. So, repeating and emphasizing the principles of radiation protection and paying more attention to these topics in the courses and internships of radiology technology students seems necessary. These measures will improve the performance of students and make them prepared to accept their future professional responsibilities.

First Performance Evaluation of an Artificial Intelligence-Based Computer-Aided Detection System for Pulmonary Nodule Evaluation in Dual-Source Photon-Counting Detector CT at Different Low-Dose Levels.

The aim of this study was to evaluate the image quality (IQ) and performance of an artificial intelligence (AI)-based computer-aided detection (CAD) system in photon-counting detector computed tomography (PCD-CT) for pulmonary nodule evaluation at different low-dose levels. An anthropomorphic chest-phantom containing 14 pulmonary nodules of different sizes (range, 3-12 mm) was imaged on a PCD-CT and on a conventional energy-integrating detector CT (EID-CT). Scans were performed with each of the 3 vendor-specific scanning modes (QuantumPlus [Q+], Quantum [Q], and High Resolution [HR]) at decreasing matched radiation dose levels (volume computed tomography dose index ranging from 1.79 to 0.31 mGy) by adapting IQ levels from 30 to 5. Image noise was measured manually in the chest wall at 8 different locations. Subjective IQ was evaluated by 2 readers in consensus. Nodule detection and volumetry were performed using a commercially available AI-CAD system. Subjective IQ was superior in PCD-CT compared with EID-CT (P < 0.001), and objective image noise was similar in the Q+ and Q-mode (P > 0.05) and superior in the HR-mode (PCD 55.8 ± 11.7 HU vs EID 74.8 ± 5.4 HU; P = 0.01). High resolution showed the lowest image noise values among PCD modes (P = 0.01). Overall, the AI-CAD system delivered comparable results for lung nodule detection and volumetry between PCD- and dose-matched EID-CT (P = 0.08-1.00), with a mean sensitivity of 95% for PCD-CT and of 86% for dose-matched EID-CT in the lowest evaluated dose level (IQ5). Q+ and Q-mode showed higher false-positive rates than EID-CT at lower-dose levels (IQ10 and IQ5). The HR-mode showed a sensitivity of 100% with a false-positive rate of 1 even at the lowest evaluated dose level (IQ5; CDTIvol, 0.41 mGy). Photon-counting detector CT was superior to dose-matched EID-CT in subjective IQ while showing comparable to lower objective image noise. Fully automatized AI-aided nodule detection and volumetry are feasible in PCD-CT, but attention has to be paid to false-positive findings.