Computed Tomography Radiation Exposure Research Articles

Imaging the Impact: Computed Tomography Thorax in COVID-19 - A Comprehensive Review and Clinical Analysis

This comprehensive review and clinical analysis explore the pivotal role of thorax computed tomography (CT) in the context of COVID-19. As the world grapples with the ongoing pandemic, the need for effective diagnostic tools and management strategies remains paramount. This review meticulously examines the impact of thorax CT imaging on the understanding, diagnosis, and clinical management of COVID-19. The review encompasses an extensive analysis of the existing literature, shedding light on the nuances of thorax CT findings in COVID-19 patients. It explores the characteristic imaging features, such as ground-glass opacities, consolidations, and other pulmonary abnormalities, providing insights into the pathophysiology of the disease. Furthermore, the clinical analysis component synthesizes data from diverse studies to elucidate the diagnostic accuracy and sensitivity of thorax CT, particularly in cases where molecular testing may present challenges. The review also delves into the role of thorax CT in early detection, risk stratification, and longitudinal monitoring of patients with COVID-19, offering valuable perspectives for healthcare professionals. Importantly, considerations of radiation exposure and ethical use of thorax CT are addressed, emphasizing the judicious integration of imaging into clinical practice. The article concludes with practical recommendations for optimizing the utility of thorax CT in the broader context of COVID-19 diagnosis and patient care.

Quantitative assessment of occupational radiation exposure in CT: a comparative study using two radiation survey meters for year-long dose monitoring of staff

Introduction: Computed Tomography (CT) is crucial in medical imaging but exposes healthcare workers to ionizing radiation. It is essential to quantify and mitigate occupational radiation exposure. This study provides a comprehensive quantitative analysis of CT settings, using two radiation survey meters, over a year-long monitoring period. Methodology: Healthcare workers operating CT scanners were included. Two radiation survey meters, Meter A (GMC-300E, uSv/h) and Meter B (RAR R311516, uSv/h), were used concurrently for continuous measurement and recording of radiation doses. Statistical analysis compared data from both meters and assessed compliance with regulatory limits and quality assurance standards. Results: The study demonstrated excellent consistency in dose measurements between Meter A and Meter B throughout the year, with no statistically significant discrepancies (p≤; 0.05). Cumulative radiation doses of staff remained within legal limits, indicating the efficacy of current safety measures. Conclusion: The study highlights the reliability of Meter A and Meter B for measuring occupational radiation exposure in CT settings. The convergence of results emphasizes their suitability for healthcare settings requiring precise radiation dose monitoring, enhancing radiation safety in CT scanning and protecting healthcare personnel from ionizing radiation exposure.

Sparse-view image reconstruction with total-variation minimization applied to sparsely sampled projection data from SiPM-based photon-counting CT

We constructed a sparse-view computed tomography (CT) system that combines a compressed sensing (CS)-based image-reconstruction algorithm and SiPM-based photon-counting (PC) CT. CS-based image-reconstruction algorithms have been extensively studied for X-ray CT image reconstruction using fewer projections because they are expected to reduce CT imaging time and radiation exposure while maintaining CT image quality. In most previous studies, CS-based image-reconstruction algorithms have been applied to data obtained through numerical simulations or conventional dual-energy CT. However, studies on PC-CT have been scarce. Therefore, we applied a CS-based image-reconstruction algorithm to the projection data obtained using our previously established SiPM-based PC-CT system and evaluated its image quality. We prepared static phantoms equivalent to iodine-containing contrast agents and a mouse model injected with iodine-containing contrast agents as subjects. Thereafter, CT scanning was performed. The obtained projection data were downsampled to simulate a sparse-view situation, and a CS-based image-reconstruction algorithm with total-variation minimization was applied. Consequently, sparse-view CT images were successfully reconstructed, and the image quality was maintained even after downsampling the projection data (downsampling ratios of 1/10 and 1/2 for the rod phantom and mouse model, respectively). Thus, the imaging time and exposure dose could be remarkably reduced (by a factor of 10 or 2), indicating that the CS-based image-reconstruction algorithm is effective for PC-CT.

PAE planning: Radiation exposure and image quality of CT and CBCT

PurposeTo determine accurate organ doses, effective doses, and image quality of computed tomography (CT) compared with cone beam CT (CBCT) for correct identification of prostatic arteries. MethodA dual-energy CT scanner and a flat-panel angiography system were used. Dose measurements (gallbladder (g), intestine (i), bladder (b), prostate (p), testes (t), active bone marrow of pelvis (bmp) and femura (bmf)) were performed using an anthropomorphic phantom with 65 thermoluminescent dosimeters in the pelvis and abdomen region. For the calculation of the contrast-to-noise ratio (CNR) of the pelvic arteries, a patient whose weight and height were almost identical to those of the phantom was selected for each examination type. ResultsThe effective dose of CT was 2.7 mSv and that of CBCT was 21.8 mSv. Phantom organ doses were lower for CT than for CBCT in all organs except the testes (g: 1.2 mGy vs. 3.3 mGy, i: 5.8 mGy vs. 23.9 mGy, b: 6.9 mGy vs. 19.4 mGy, p: 6.4 mGy vs. 13.2 mGy, t: 4.7 mGy vs. 2.4 mGy, bmp: 5.1 mGy vs. 18.2 mGy, bmf: 3.3 mGy vs. 6.6 mGy). For human pelvic arteries, the CNR of CT was better than that of CBCT, with the exception of one prostate artery that showed stenosis on CT. Evaluation by experienced radiologists also confirmed the better detectability of prostate arteries on CT examination. ConclusionsIn our study preprocedural CT had lower organ doses and better image quality comparedd with CBCT and should be considered for the correct identification of prostatic arteries.

Risk of hematological malignancies from CT radiation exposure in children, adolescents and young adults

Over one million European children undergo computed tomography (CT) scans annually. Although moderate- to high-dose ionizing radiation exposure is an established risk factor for hematological malignancies, risks at CT examination dose levels remain uncertain. Here we followed up a multinational cohort (EPI-CT) of 948,174 individuals who underwent CT examinations before age 22 years in nine European countries. Radiation doses to the active bone marrow were estimated on the basis of body part scanned, patient characteristics, time period and inferred CT technical parameters. We found an association between cumulative dose and risk of all hematological malignancies, with an excess relative risk of 1.96 (95% confidence interval 1.10 to 3.12) per 100 mGy (790 cases). Similar estimates were obtained for lymphoid and myeloid malignancies. Results suggest that for every 10,000 children examined today (mean dose 8 mGy), 1–2 persons are expected to develop a hematological malignancy attributable to radiation exposure in the subsequent 12 years. Our results strengthen the body of evidence of increased cancer risk at low radiation doses and highlight the need for continued justification of pediatric CT examinations and optimization of doses.

Lowering head computed tomography radiation dose for craniosynostosis: An institutional change and review of literature

Definitive diagnosis of Craniosynostosis (CS) with computed tomography (CT) is readily available, however, exposure to ionizing radiation is often a hard stop for parents and practitioners. Lowering head CT radiation exposure helps mitigate risks and improves diagnostic utilization. The purpose of the study is to quantify radiation exposure from head CT in patients with CS using a ‘new’ (ultra-low dose) protocol; compare prior standard CT protocol; summarize published reports on cumulative radiation doses from pediatric head CT scans utilizing other low-dose protocols. A retrospective study was conducted on patients undergoing surgical correction of CS, aged less than 2 years, between August 2014 and February 2022. Cumulative effective dose (CED) in mSv was calculated, descriptive statistics were performed, and mean ± SD was reported. A literature search was conducted describing cumulative radiation exposure from head CT in pediatric patients and analyzed for ionizing radiation measurements. Forty-four patients met inclusion criteria: 17 females and 27 males. Patients who obtained head CT using the ‘New’ protocol resulted in lower CED exposure of 0.32 mSv ± 0.07 compared to the prior standard protocol at 5.25 mSv ± 2.79 (p < 0.0001). Five studies specifically investigated the reduction of ionizing radiation from CT scans in patients with CS via the utilization of low-dose CT protocols. These studies displayed overall CED values ranging from 0.015 mSv to 0.77 mSv. Our new CT protocol resulted in 94% reduction of ionizing radiation. Ultra-low dose CT protocols provide similar diagnostic data without loss of bone differentiation in CS and can be easily incorporated into the workflow of a children’s hospital.

Lowering head computed tomography radiation dose for craniosynostosis: An institutional change and review of literature

Definitive diagnosis of Craniosynostosis (CS) with computed tomography (CT) is readily available, however, exposure to ionizing radiation is often a hard stop for parents and practitioners. Lowering head CT radiation exposure helps mitigate risks and improves diagnostic utilization. The purpose of the study is to quantify radiation exposure from head CT in patients with CS using a ‘new’ (ultra-low dose) protocol; compare prior standard CT protocol; summarize published reports on cumulative radiation doses from pediatric head CT scans utilizing other low-dose protocols. A retrospective study was conducted on patients undergoing surgical correction of CS, aged less than 2 years, between August 2014 and February 2022. Cumulative effective dose (CED) in mSv was calculated, descriptive statistics were performed, and mean ± SD was reported. A literature search was conducted describing cumulative radiation exposure from head CT in pediatric patients and analyzed for ionizing radiation measurements. Forty-four patients met inclusion criteria: 17 females and 27 males. Patients who obtained head CT using the ‘New’ protocol resulted in lower CED exposure of 0.32 mSv ± 0.07 compared to the prior standard protocol at 5.25 mSv ± 2.79 (p < 0.0001). Five studies specifically investigated the reduction of ionizing radiation from CT scans in patients with CS via the utilization of low-dose CT protocols. These studies displayed overall CED values ranging from 0.015 mSv to 0.77 mSv. Our new CT protocol resulted in 94% reduction of ionizing radiation. Ultra-low dose CT protocols provide similar diagnostic data without loss of bone differentiation in CS and can be easily incorporated into the workflow of a children’s hospital.

Risks of leukemia, intracranial tumours and lymphomas in childhood and early adulthood after pediatric radiation exposure from computed tomography.

Children are more susceptible to radiation-induced damage than adults, but little research has compared the risk of cancer after exposure to radiation during computed tomography (CT) among children at different ages. We aimed to explore the risk of intracranial tumours, leukemia or lymphoma among children, adolescents and young adults (aged < 25 yr) after radiation exposure from CT at or before the age of 18 years. We conducted a nested, population-based case-control study using data from Taiwan's publicly funded health care system. We identified participants younger than 25 years with newly diagnosed intracranial tumours, leukemia or lymphoma, from Jan. 1, 2000, to Dec. 31, 2013. We assigned 10 non-cancer controls for each case, matching by sex, date of birth and day of entry to the cohort. We considered CT scans received at or before the age of 18 years and 3 or more years before the index date (the date of cancer diagnosis for cases) as exposure. We used conditional logistic regression models and incidence rate ratios (IRRs) to estimate the relationship between risk of these cancers and CT radiation exposure. We identified 7807 cases and matched to 78 057 controls. Compared with no exposure, exposure to a single pediatric CT scan did not increase risk of intracranial tumours, leukemia or lymphoma. However, participants exposed to 4 or more CT scans had an elevated incidence (IRR 2.30, 95% confidence interval 1.43-3.71) of one of the cancer outcomes of interest. Receiving 4 or more CT scans at or before 6 years of age was associated with the highest risks of cancer, followed by ages 7-12 years and 13-18 years (p for trend < 0.001). Exposure to a single CT scan was not associated with increased risks of subsequent intracranial tumours, leukemia or lymphoma among children; however, we observed increased cancer risks among those with 4 or more CT scans, especially among younger children. Although these cancers are uncommon, the findings of this study underscore the importance of prudent use of CT in the pediatric population.

Tradeoffs between Radiation Exposure to the Lens of the Eyes and Diagnostic Image Quality in Pediatric Brain Computed Tomography.

Computed tomography (CT) of the brain is associated with radiation exposure to the lens of the eyes. Therefore, it is necessary to optimize scan settings to keep radiation exposure as low as reasonably achievable without compromising diagnostic image information. The aim of this study was to compare the effectiveness of the five practical techniques for lowering eye radiation exposure and their effects on diagnostic image quality in pediatric brain CT. The following scan protocols were performed: reference scan, 0.06-mm Pbeq bismuth shield, 30% globally lowering tube current (GLTC), reducing tube voltage (RTV) from 120 to 90 kVp, gantry tilting, and combination of gantry tilting with bismuth shielding. Radiation measurements were performed using thermoluminescence dosimeters. Objective and subjective image quality was evaluated. All strategies significantly reduced eye dose, and increased the posterior fossa artifact index and the temporal lobe artifact index, relative to the reference scan. GLTC and RTV increased image noise, leading to a decrease signal-to-noise ratio and contrast-to-noise ratio. Except for bismuth shielding, subjective image quality was relatively the same as the reference scan. Gantry tilting may be the most effective method for reducing eye radiation exposure in pediatric brain CT. When the scanner does not support gantry tilting, GLTC might be an alternative.

Is It Possible to Replace Conventional Radiography (CR) with a Dose Neutral Computed Tomography (CT) of the Cervical Spine in Emergency Radiology-An Experimental Cadaver Study.

The purpose of this experimental study on recently deceased human cadavers was to investigate whether (I) the radiation exposure of the cervical spine CT can be reduced comparable to a dose level of conventional radiography (CR); and (II) whether and which human body parameters can be predictive for higher dose reduction potential (in this context). Materials and Methods: Seventy serial CT scans of the cervical spine of 10 human cadavers undergoing postmortem virtual autopsy were taken using stepwise decreasing upper limits of the tube current (300 mAs, 150 mAs, 110 mAs, 80 mAs, 60 mAs, 40 mAs, and 20 mAs) at 120 kVp. An additional scan acquired at a fixed tube current of 300 mAs served as a reference. Images were reconstructed with filtered back projection and the upper (C1-4) and lower (C4-7) cervical spine were evaluated by three blinded readers for image quality, regarding diagnostic value and resolution of anatomical structures according to a semiquantitative three-point-scale. Dose values and individual physical parameters were recorded. The relationship of diagnostic IQ, dose reduction level, and patients’ physical parameters were investigated. The high-contrast resolution of the applied CT protocols was tested in an additional phantom study. Results: The IQ of the upper cervical spine was diagnostic at 1.69 ± 0.58 mGy (CTDI) corresponding to 0.20 ± 0.07 mSv (effective dose) in all cadavers. IQ of the lower cervical spine was diagnostic at 4.77 ± 1.86 mGy corresponding to 0.560 ± 0.21 mSv (effective dose) in seven cadavers and at 2.60 ± 0.93 mGy corresponding to 0.31 ± 0.11 mSv in four cadavers. Significant correlation was detected for BMI (0.8366; p = 0.002548) and the anteroposterior (a.p.) chest diameter (0.8363; p = 0.002566), shoulder positioning (0.79799; p = 0.00995), and radiation exposure. Conclusions: Conventional radiography can be replaced with a nearly dose-neutral CT scan of the cervical spine.

Understanding the harm of low-dose computed tomography radiation to the body (Review).

Computed tomography (CT) is a modern examination method whose radiation characteristics vary depending on the population groups, the part of the body being examined, and other implementation conditions. The use of CT has become increasingly widespread. However, there is a growing concern regarding the harm caused by CT radiation. The opinions regarding whether low-dose CT can induce cancer differ. It is necessary to consider the research population, radiation characteristics, and different parts of the body being exposed to radiation before the application of radiation to ensure the knowledge used is scientifically sound and reasonable. Therefore, different studies have different opinions on whether low-dose CT induces cancer, and not all physicians are aware of this. The present review article aimed to impart relevant insights and a correct understanding of the hazardous effects of low-dose CT radiation on the human body and help physicians reduce unnecessary CT radiation exposure.

Non-Hemorrhagic Adrenal Infarction during Pregnancy: The Diagnostic Imaging Keys.

Background: non-hemorrhagic adrenal infarction (NHAI) is a rare cause of acute abdominal/flank pain during pregnancy; in order to ensure prompt and appropriate treatment, this diagnosis should not be overlooked. This case series highlights pertinent imaging findings, including ultrasounds (USs), computed tomography (CT), and magnetic resonance imaging (MRI) of recent NHAI cases. Methods: we compiled all consecutive NHAI cases from two university hospitals over a two-year period and checked the relevant clinical, laboratory, and imaging findings. Relevant articles on NHAI published from January 2010 to March 2021 were analyzed. Results: six cases were found in our database. CT-scans typically showed enlarged, hypodense, and non-enhanced adrenal glands. Unenhanced MRIs allowed for diagnoses and showed enlarged adrenal glands in the signal hyperintensity on T2 and diffusion-weighted imaging, without any signal hyperintensity on T1. In two of our six cases, USs showed swollen adrenal glands with fluid collection. Conclusion: NHAI and its differential diagnosis—in cases of acute pain during pregnancy—highlight the crucial roles of integrated radiological examination and cooperation between obstetricians and radiologists, both of whom should consider the location of the pain, the accessibility and tolerance of MRI, and the radiation exposure of CT. Despite its supposed poor sensitivity, an US performed because the patient reports pain should also be used to examine the adrenal gland regions. Non-enhanced MRI is clearly of value and access to it in emergencies is important to avoid radiation exposure

Prospective evaluation of an evidence-based decision tool to assess pediatric blunt abdominal trauma (BAT).

Computed tomography (CT) is currently the standard for evaluation of intra-abdominal injury (IAI) after BAT. Pediatric patients receiving CT scans based on adult clinical protocols are potentially exposed to unnecessary radiation. The purpose of this study is to determine the rate of CT scans before and after implementation of a pediatric BAT decision tool. We adapted and implemented an evidence-based decision tool for pediatric BAT based on five clinical variables. We reviewed patient charts 18months pre- and post-implementation. Demographics and outcomes were compared using Chi-square and Fisher's exact test, accordingly. The pre and post-implementation groups were uniform when comparing age, sex, mechanism, and Injury Severity Score. The decision tool was utilized in 85% of patients post-implementation. Fewer CT scans were obtained in the post-implementation group (28 vs. 21%, p = 0.215) with no missed injuries or late diagnoses. Implementation of a pediatric BAT decision tool decreased CT usage and radiation exposure without an obvious compromise to patient care. This experience supports the utilization of these tools for the assessment of IAI after BAT and have resulted in more selective use of CT during pediatric BAT in our program.

The association between exposure to radiation and the incidence of cataract.

To examine the association between exposure to radiation from computed tomography (CT) studies and the incidence of cataract. In a nested case-control study, all cataract cases and their matched controls were sampled from a retrospective cohort of Israeli residents who underwent CT scans or ultrasonic tests in Soroka Medical Center, Beer-Sheva, Israel, between the years 1996 and 2014. The risk of cataract associated with head, neck or the rest of the body CT was assessed using Poisson survival analysis. The nested matched sample included 3841 cataract cases and their age- and sex-matched controls (n = 228,743). CT radiation exposure was more frequent in the cataract group, with 9.7% head CT, 1.2% neck CT and 6.6% other CT, compared to 5%, 0.7% and 3.7% among person-years without cataract (p < 0.001). In a multivariate analysis, a similar increased risk of cataract associated with head (hazard ratio (HR): 1.24, 95% confidence interval (CI): 1.11; 1.38) and other CT (HR: 1.25, 95% CI: 1.10; 1.43) was found. No association with neck CT (HR: 1.07, 95% CI: 0.80; 1.43) was observed. In our study population, a similar risk of cataract with head, neck or the rest of the body CT was detected.

Radiologists' Knowledge and Attitudes towards CT Radiation Dose and Exposure in Saudi Arabia-A Survey Study.

Computed tomography (CT) is a key imaging technique in diagnostic radiology, providing highly sensitive and specific information. While its use has increased dramatically in recent years, the quantity and associated risks of radiation from CT scans present major challenges, particularly in paediatrics. The fundamental principles of radiation protection require that radiation quantities be as low as reasonably achievable and CT use must be justified, particularly for paediatric patients. CT radiation knowledge is a key factor in optimising and minimising radiation risk. The objective of this study was to analyse knowledge level, expertise, and competency regarding CT radiation dose and its hazards in paediatrics among radiologists in Saudi Arabian hospitals. A self-reported, multiple-choice questionnaire assessed the attitudes and opinions of radiologists involved in imaging studies using ionising radiation. Among the total respondents, 65% ± 13.5% had a good comprehension of the dangers of carcinogenicity to the patient resulting from CT scans, with 80% presuming that cancer risks were elevated. However, only 48.5%, 56.5%, and 65% of the respondents were aware of specific radiation risks in head, chest, and abdominal paediatric examinations, respectively. Regular, frequent, and specific training courses are suggested to improve the fundamental knowledge of CT radiation among radiologists and other physicians.

Radiation Exposure Associated With Computed Tomography in Childhood and the Subsequent Risk of Cancer: A Meta-Analysis of Cohort Studies.

Background:Computed tomography (CT) is used worldwide; however, recent studies suggest that CT radiation exposure during childhood may be a risk factor for cancer, although the data are inconsistent.Methods:A comprehensive search of electronic databases including PubMed, SpringerLink, Embase, Cochrane Library, Elsevier/ScienceDirect, Medline, Orbis, and Web of Science databases from January 1990 to November 2018 for observational epidemiologic studies reporting associations between radiation exposure from CT in childhood and the subsequent risk of cancer was conducted. A linear model was used to explore the dose–response relationship.Results:Seven studies with 1180 987 children enrolled were included. The risk of later cancer was 1.32-fold higher for children exposed to CT than those without exposure. Compared to those not exposed to pediatric CT, the relative risk (RRs) were larger for the higher doses but with wider CIs (RR for 5-10 mGy: 0.90, 95% CI: 0.69-1.12; RR for 10-15 mGy: 1.02, 95% CI: 0.86-1.18; RR for >15 mGy: 1.13, 95% CI: 0.97-1.30), the leukemia risk was higher in exposed children (RR: 1.23, 95% CI: 1.10-1.36), and brain cancer risk was higher in exposed children (RR: 1.54, 95% CI: 0.84-2.45).Conclusions:Our analysis suggested that radiation exposure from CT during childhood is associated with a subsequently elevated risk of cancer. However, caution is needed when interpreting these results because of the heterogeneity among the studies. The findings should be confirmed in further studies with longer follow-up periods.

The Feasibility of Fast MRI to Reduce CT Radiation Exposure With Acute Traumatic Head Injuries.

* Abbreviations: CT — : computed tomography ED — : emergency department TBI — : traumatic brain injury Traumatic brain injuries (TBIs) are among the most common causes of pediatric morbidity and mortality globally. After acute head trauma, children at risk for clinical deterioration must be identified rapidly and accurately, usually in the emergency department (ED) setting. Neuroimaging by computed tomography (CT) for pediatric head trauma proliferated rapidly in the late 1990s1 and remains the diagnostic gold standard for the identification of clinically important TBIs. Therein lies the problem: the risk of missing significant intracranial pathology must be weighted against the risks of radiation-induced malignancy associated with CT imaging.2–4 Reducing CT scans for head-injured children has been the focus of international research5–8 and educational campaigns for nearly 2 decades.9–11 Despite these long-standing efforts, neuroimaging of head-injured children by CT remains elevated.12 MRI presents a potentially attractive alternative to CT that would not expose children to the harmful effects of ionizing radiation. However, the use of MRI for pediatric head trauma has traditionally been limited by the need to remain motionless for a prolonged period and frequently necessitates procedural sedation with its additional inherent risks. A fast MRI protocol that is motion tolerant and sensitive for brain injury would curtail the limitations of conventional MRI. Previous … Address correspondence to Brett Burstein, MDCM, PhD, MPH, Division of Pediatric Emergency Medicine, Department of Pediatrics, Montreal Children’s Hospital, McGill University Health Center, 1001 Decarie Blvd, Montreal, QC H4C 3J1, Canada. E-mail: brett.burstein{at}mail.mcgill.ca

Comparison of the Harms, Advantages, and Costs Associated With Alternative Guidelines for the Evaluation of Hematuria

Existing recommendations for the diagnostic testing of hematuria range from uniform evaluation of varying intensity to patient-level risk stratification. Concerns have been raised about not only the costs and advantages of computed tomography (CT) scans but also the potential harms of CT radiation exposure. To compare the advantages, harms, and costs associated with 5 guidelines for hematuria evaluation. A microsimulation model was developed to assess each of the following guidelines (listed in order of increasing intensity) for initial evaluation of hematuria: Dutch, Canadian Urological Association (CUA), Kaiser Permanente (KP), Hematuria Risk Index (HRI), and American Urological Association (AUA). Participants comprised a hypothetical cohort of patients (n = 100 000) with hematuria aged 35 years or older. This study was conducted from August 2017 through November 2018. Under the Dutch and CUA guidelines, patients received cystoscopy and ultrasonography if they were 50 years or older (Dutch) or 40 years or older (CUA). Under the KP and HRI guidelines, patients received different combinations of cystoscopy, ultrasonography, and CT urography or no evaluation on the basis of risk factors. Under the AUA guidelines, all patients 35 years or older received cystoscopy and CT urography. Urinary tract cancer detection rates, radiation-induced secondary cancers (from CT radiation exposure), procedural complications, false-positive rates per 100 000 patients, and incremental cost per additional urinary tract cancer detected. The simulated cohort included 100 000 patients with hematuria, aged 35 years or older. A total of 3514 patients had urinary tract cancers (estimated prevalence, 3.5%; 95% CI, 3.0%-4.0%). The AUA guidelines missed detection for the fewest number of cancers (82 [2.3%]) compared with the detection rate of the HRI (116 [3.3%]) and KP (130 [3.7%]) guidelines. However, the simulation model projected 108 (95% CI, 34-201) radiation-induced cancers under the KP guidelines, 136 (95% CI, 62-229) under the HRI guidelines, and 575 (95% CI, 184-1069) under the AUA guidelines per 100 000 patients. The CUA and Dutch guidelines missed detection for a larger number of cancers (172 [4.9%] and 251 [7.1%]) but had 0 radiation-induced secondary cancers. The AUA guidelines cost approximately double the other 4 guidelines ($939/person vs $443/person for Dutch guidelines), with an incremental cost of $1 034 374 per urinary tract cancer detected compared with that of the HRI guidelines. In this simulation study, uniform CT imaging for patients with hematuria was associated with increased costs and harms of secondary cancers, procedural complications, and false positives, with only a marginal increase in cancer detection. Risk stratification may optimize the balance of advantages, harms, and costs of CT.

Computed Tomography Radiation Exposure Among Referred Kidney Stone Patients: Results from the Registry for Stones of the Kidney and Ureter.

Purpose: Kidney stone patients routinely have CT scans during diagnostic work-up before being referred to a tertiary center. How often these patients exceed the recommended dose limits for occupational radiation exposure of >100 mSv for 5 years and >50 mSv in a single year from CT alone remains unknown. This study aimed to quantify radiation doses from CTs received by stone patients before their evaluation at a tertiary care stone clinic. Methods: From November 2015 to March 2017, consecutive new patients enrolled into the Registry for Stones of the Kidney and Ureter (ReSKU™) had the dose-length product of every available CT abdomen/pelvis within 5 years of their initial visit recorded, allowing for an effective dose (EDose) calculation. Multivariate logistic regression analysis identified factors associated with exceeding recommended dose limits. Models were created to test radiation reducing effects of low-dose and phase-reduction CT protocols. Results: Of 343 noncontrast CTs performed, only 29 (8%) were low-dose CTs (calculated EDose <4 mSv). Among 389 total patients, 101 (26%) and 25 (6%) had an EDose >20 mSv and >50 mSv/year, respectively. Increased body mass index, number of scans, and multiphase scans were associated with exceeding exposure thresholds (p < 0.01). The implementation of a low-dose CT protocol decreased the estimated number of scans contributing to overexposure by >50%. Conclusions: Stone patients referred to a tertiary stone center may receive excessive radiation from CT scans alone. Unnecessary phases and underutilization of low-dose CT protocols continue to take place. Enacting new approaches to CT protocols may spare stone patients from exceeding recommended dose limits.

Domain Progressive 3D Residual Convolution Network to Improve Low-Dose CT Imaging.

The wide applications of X-ray computed tomography (CT) bring low-dose CT (LDCT) into a clinical prerequisite, but reducing the radiation exposure in CT often leads to significantly increased noise and artifacts, which might lower the judgment accuracy of radiologists. In this paper, we put forward a domain progressive 3D residual convolution network (DP-ResNet) for the LDCT imaging procedure that contains three stages: sinogram domain network (SD-net), filtered back projection (FBP), and image domain network (ID-net). Though both are based on the residual network structure, the SD-net and ID-net provide complementary effect on improving the final LDCT quality. The experimental results with both simulated and real projection data show that this domain progressive deep-learning network achieves significantly improved performance by combing the network processing in the two domains.