Development of Animation Projector System and Usefulness in Pediatric Head CT

According to the 2011 ICRP statement, the threshold in absorbed dose for the lens of the eye is now considered to be 0.5 Gy. Therefore, it is important to keep the eye lens doses during head computed tomography examination as low as reasonably achievable. In this study, the two lenses and the occiput doses associated with patient setup errors and head size were evaluated using phantoms developed for pediatric patients. The phantoms were made using flexible acrylic sheets in a cylindrical shape [diameters of 6 (premature baby), 8 (neonate), 10 (infant), and 12 cm (child)] and placed on the end of the CT bed. The bed position was raised from the center for each phantom size. The two lenses and the occiput doses at each setup were measured using radiochromic film. By raising the bed position, the two lenses doses decreased at all phantom sizes. However, the occiput doses changed in a complex manner according to the phantom size. In this study, decreasing the distance from the lens to the X-ray tube (i.e. raising the bed position) is an effective way to reduce the absorbed dose of the lens. However, when the occiput was positioned at the center of the gantry aperture, the occiput dose peaked in all phantom sizes. In addition, the results indicated a complex dose distribution in pediatric head CT when taking into account the bed position (patient setup errors) and phantom sizes. Furthermore, beam slice width and pitch are important factor in determining the maximum absorbed dose. To keep radiation doses during CT examination as low as reasonably achievable, it is important to clarify the influence of CT scanning settings on CT dose.

Medical radiation from CT should be kept as low as reasonably achievable (ALARA), particularly in young patients. To examine radiation dose from head CT in children in a trauma center (TC) and a regional children's hospital (RCH). A random sample of 240 children (0-3, 4-9, 10-14 years of age) from the TC were compared with a similar cohort from the RCH. All children had undergone at least one head CT scan without contrast enhancement; data from PACS and Department of Radiology Information System were used to estimate normalized effective dose (ED). Lifetime attributable risk of cancer incidence was estimated using the Biologic Effects of Ionizing Radiation (BEIR) VII report. The mean normalized ED was significantly higher in the youngest children at the TC (2.74 mSv in those aged 0-3 years vs. 2.23 mSv in those aged 10-14 years; P<0.001) and at the RCH (2.44 mSv in those aged 0-3 years vs. 1.71 mSv in those aged 10-14 years; P<0.001). Each decreasing year of age was independently associated with a 0.06 mSv higher mean normalized ED (P<0.001). After adjusting for the age difference between the institutions, the mean normalized ED was 0.44 mSv lower at the RCH than at the TC across all ages (95% CI 0.31-0.58, P<0.001). A higher lifetime attributable risk of cancer was associated with younger age. The radiation dose from head CT in children as defined by the normalized ED was highest in the youngest children and varied significantly between institutions in this bi-institutional study.

The establishment of local diagnostic reference levels for pediatric CT

Together with quantile regression methods, such a model would have the potential for clinical utility through automated quantitative comparison of individual cases relative to their age and gender-matched peer group. Our aim was to demonstrate the automated processing of digital clinical head CT data in the development of a clinically useful model of age-related changes of the brain in the first 2 decades of life. A total of 415 (209 female) consecutive, clinical head CTs with radiographically normal findings from patients from birth through 20 years of age were retrospectively selected and subjected to automated segmentation. Brain volume, brain parenchymal fraction, brain radiodensity, and brain radiomass were assessed as a function of patient age. Statistical modeling and quantile regression were performed. Brain volume increased from 400 cm3 at birth to 1350 cm3 at 20 years of age (>3-fold). Males had a slightly steeper growth trajectory than females, with approximately 8% difference in volume between the sexes established in the first few years of life. Brain parenchymal fraction was variable at younger than 2 years of age, stabilizing between 0.85 and 0.92 at 2-3 years of age. Brain mean radiodensity was lower at birth (24 HU) and increased through 3 years of age, after which it stabilized near 30 HU, an approximately 25% increase. The product of brain volume and mean brain radiodensity (radiomass), increased from 700 HU × mL at birth to 3900 HU × mL, a 5.6-fold increase, with approximately 5% difference between males and females at 20 years. Quantile regression enables a given metric to be interpreted relative to an age- and sex-matched peer group. Automated segmentation of clinical head CT images permitted the generation of a reference database for quantitative analysis of pediatric and adolescent brains. Quantile regression facilitates clinical application.

Head CT scans are considered the imaging modality of choice to screen patients with head trauma for neurocranial injuries; however, widespread CT imaging is not recommended and much research has been conducted to establish objective clinical predictors of intracranial injury (ICI) in order to optimize the use of neuroimaging in children with minor head trauma. To evaluate whether a strict application of the New Orleans Criteria (NOC), Canadian CT Head Rule (CCHR) and National Emergency X-Radiography Utilization Study II (NEXUS II) in pediatric patients with head trauma presenting to a non-trauma center (level II) could reduce the number of cranial CT scans performed without missing clinically significant ICI. We conducted an IRB-approved retrospective analysis of pediatric patients with head trauma who received a cranial CT scan between Jan. 1, 2001, and Sept. 1, 2008, and identified which patients would have required a scan based on the criteria of the above listed decision instruments. We then determined the sensitivities, specificities and negative predictive values of these aids. In our cohort of 2,101 patients, 92 (4.4%) had positive head CT findings. The sensitivities for the NOC, CCHR and NEXUS II were 96.7% (95%CI 93.1-100), 65.2% (95%CI 55.5-74.9) and 78.3% (95%CI 69.9-86.7), respectively, and their negative predictive values were 98.7%, 97.6% and 97.2%, respectively. In contrast, the specificities for these aids were 11.2% (95%CI 9.8-12.6), 64.2% (95%CI 62.1-66.3) and 34.2% (95%CI 32.1-36.3), respectively. Therefore, in our population it would have been possible to scan at least 10.9% fewer patients. The number of cranial CT scans conducted in our pediatric cohort with head trauma would have been reduced had any of the three clinical decision aids been applied. Therefore, we recommend that further validation and adoption of pediatric head CT decision aids in non-trauma centers be considered to ultimately increase patient safety while reducing medical expense.

The purpose of this study was to investigate the effects of an organ-based tube-current modulation (OBTCM) system on image quality and age-specific dose in head and chest CT examinations. Image noise, contrast-to-noise ratio (CNR) and image entropy were assessed using statistical and entropy analyses. Radiation doses for newborn, 6-y-old child and adult phantoms were measured with in-phantom dosimetry systems. The quality of CT images obtained with OBTCM was not different from that obtained without OBTCM. In head CT scans, the eye lens dose decreased by 20-33 % using OBTCM. In chest CT scans, breast dose decreased by 5-32 % using OBTCM. Posterior skin dose, however, increased by 11-20 % using OBTCM in head and chest CT scans. The reduction of effective dose using OBTCM was negligibly small. Detailed image quality and dose information provided in this study can be effectively used for OBTCM application.

Deep learning-based organ dose prediction in pediatric head CT using fully automated tissue segmentation and newly developed voxelized phantoms in GATE/Geant4 simulation toolkit

Background: Basal ganglia calcification (BGC) is a well-known complication of hypoparathyroidism. It is currently thought that increased serum phosphate or calcium x phosphate product may be major risk factors. However, the pathophysiology of BGC is still unclear, since the literature is largely based on limited case series or case reports. Methods: We identified a large cohort of patients with hypoparathyroidism diagnosed between 2000 and 2020 and evaluated those with head CT scans performed over this interval. Etiology and date of onset of hypoparathyroidism were determined by medical records review. All head CT scan images were reviewed to confirm radiology reports reporting BGC. We retrieved laboratory data within 10 years before the first head CT that showed incident BGC. Three age- and sex- matched controls with head CT scans were selected for each patient, and compared to the patients with hypoparathyroidism. Results: Of 1014 unique patients with a verified diagnosis of hypoparathyroidism, 142 had a head CT scan performed between 2000 and 2020. Head CT scans were performed for reasons unrelated to hypoparathyroidism in 96.5% of patients. In this cohort, 80.3% of patients (n=114) had post-surgical hypoparathyroidism. Age at which the first head CT in patients was done was 62±20.6 (range 11–97), and duration of hypoparathyroidism at the time of first head CT was 11.0±14.4 years (0–71). Prevalence of BGC in patients with hypoparathyroidism was 25.4% (n=36), as compared with 7.3% in the control group (31/426) (P<0.001). Patients and controls were similar in terms of cardiovascular risk factors (diabetes, hypertension, dyslipidemia, alcohol consumption, smoking status and BMI). In patients with non-surgical hypoparathyroidism (n=28), prevalence of BGC was 71.4% vs. 14.0% in the postsurgical cohort (OR 15.4; 95% CI 5.8–40, P<0.001). Compared to patients with hypoparathyroidism without BGC, those with BGC had lower time-weighted average serum calcium (8.4±0.8 vs. 8.8±0.8, P=0.002; normal range, 8.6–10.2 mg/dL), and lower time-weighted average calcium/phosphate ratio (Ca/P) (1.83±0.52 vs. 2.13±0.47, P=0.007). Conclusions: Basal ganglia calcification in hypoparathyroidism is associated with low serum calcium and low Ca/P ratio. This may allow increased bioavailability of phosphate in the extracellular space, leading to calcium phosphate crystal formation within the basal ganglia. Assessing Ca/P ratio may be useful to identify patients at risk for BGC. Prevalence of BGC is significantly higher in patients with non-surgical hypoparathyroidism.

Our aim in the study was to assess the eye lens dose reduction resulting from the use of radioprotective bismuth garments to shield the eyes of pediatric patients undergoing head CT. The Monte Carlo N-particle transport code and mathematical humanoid phantoms representing the average individual at different ages were used to determine eye lens dose reduction accomplished with bismuth shielding of the eye in the following simulated CT scans: (a) scanning of the orbits, (b) scanning of the whole head, and (c) 20 degrees angled scanning of the brain excluding the orbits. The effect of bismuth shielding on the eye lens dose was also investigated using an anthropomorphic phantom and thermoluminescence dosimetry (TLD). Eye lens dose reduction achieved by bismuth shielding was measured in 16 patients undergoing multiphase CT scanning of the head. The patient's scans were divided in the following: CT examinations where the eye globes were entirely included (n=5), partly included (n=6) and excluded (n=5) from the scanned region. The eye lens dose reduction depended mainly on the scan boundaries set by an operator. The average eye lens dose reduction determined by Monte Carlo simulation was 38.2%, 33.0% and <1% for CT scans of the orbits, whole head, and brain with an angled gantry, respectively. The difference between the Monte Carlo derived eye lens dose reduction factor values and corresponding values determined directly by using the anthropomorphic phantom head was found less than 5%. The mean eye lens dose reduction achieved by bismuth shielding in pediatric patients were 34%, 20% and <2% when eye globes were entirely included, partly included and excluded from the scanned region, respectively. A significant reduction in eye lens dose may be achieved by using superficial orbital bismuth shielding during pediatric head CT scans. However, bismuth garments should not be used in children when the eyes are excluded from the primarily exposed region.

Purpose:To ascertain and implement the maximum level of adaptive statistical iterative reconstruction (ASiR) that can be used to establish dose reduced pediatric head CT protocols.Methods:Noise power spectrum (NPS), modulation transfer function (MTF), and qualitative visual assessment were used as image quality metrics to calculate image quality based on filtered back projection (FBP) and ASiR reconstruction. The effect on image quality as a function of level of ASiR implementation and tube current reduction was analyzed by comparing image noise magnitude and frequency, and spatial resolution with similar measured image quality for FBP. Relative patient dose reduction was estimated using both CTDIvol and effective dose calculated using pediatric sized physical anthropomorphic phantoms. Dose reduced protocols were investigated for CT head examinations (i.e. brain, orbits, sinus, maxillary and temporal bones) by implementing ASiR and lowering CT tube current.Results:An analysis of the effects on noise texture from implementation of statistical iterative reconstruction determined that the level of ASiR that correlated closest with FBP for the GE soft reconstruction kernel (for both 100 and 120 kVp) was determined to be 30%, and for the GE standard reconstruction kernel at 100 kVp was 20% ASiR. However, implementation of 60% ASiR (GE soft reconstruction kernel) and 30% ASiR (GE standard reconstruction kernel) led to an average relative reduction in CTDIvol by 40% (range: 30%‐47%) and effective dose by 36% (range: 12%‐54%) while maintaining the same overall noise magnitude and improving the CNR of the image as compared to FBP. A coarser noise texture was visualized at 60% ASiR.Conclusion:The data in this study are provided to allow customized selection of ASiR implementation relating to acceptable tolerance for change in noise texture appearance in reconstructed images, and level of relative dose reduction for a pediatric population undergoing head CT examination.

In emergency diagnostics, head CT and CT angiography (CTA) of craniocervical vasculature are indispensable for children, despite their increased radiation sensitivity. This study assesses the radiation dose metrics of head CT and CTA in pediatric patients managed in the trauma resuscitation unit (TRU). All patients aged 0-<15 years who underwent head CT and CTA in the TRU between April 2020 and August 2023 were included. CT dose index volume (CTDIvol) and dose-length product (DLP) were extracted from the Radimetrics Enterprise Platform, which also provided organ doses estimated via Monte Carlo simulations and effective doses (ED) derived from these estimates. Dose metrics were compared with national diagnostic reference levels (DRLs), defined for three pediatric age groups: I (0-<5 years), II (5-<10 years), and III (10-<15 years). Of 212 pediatric TRU patients, 62.7% (133/212) underwent CT and 72.2% (96/133) received combined CT and CTA. Median CTDIvol and DLP increased with age, whereas ED decreased. For head CT, CTDIvol ranged from 18.9 mGy to 29.4 mGy, DLP from 282 to 460 mGycm, and ED from 1.6 to 1.3 mSv. For CTA, CTDIvol ranged from 1.4 to 2.2 mGy, DLP from 40 to 83 mGycm, and ED from 1.0 to 0.8 mSv. All doses remained below national DRLs. Head CT and CTA in pediatric trauma can be performed with radiation doses well below national DRLs. Careful dose management is important to reduce potential long-term cancer risks and deterministic effects such as lens cataract formation.

Serum GFAP and UCH-L1 for prediction of absence of intracranial injuries on head CT (ALERT-TBI): a multicentre observational study

Background: Timely and accurate diagnosis of large vessel occlusions in CT head and CTA scans is crucial for stroke patient management. Maximum Intensity Projection (MIP) reconstructions have emerged as a potential aid in improving diagnostic accuracy for large vessel occlusions. Methods: This comparative diagnostic accuracy study was conducted at the Dammam Medical Complex in Saudi Arabia, involving ten radiology residents from different experience levels. Residents reviewed 10 cases each, with half accompanied by MIP reconstructions. They assessed occlusion presence and rated their confidence using a Likert scale. Results: Junior and senior residents exhibited similar correct detection rates (86.0% vs. 78.0%, p = 0.298) and confidence levels (4.3 vs. 4.3, p = 0.772) but differed in evaluation time (201.9 seconds vs. 133.7 seconds, p &lt; 0.001). MIP usage exhibited positive trends in correct detection rates and shorter evaluation times for senior residents but lacked statistical significance. In the feedback analysis, a clear majority of 90% of the residents expressed agreement or strong agreement that MIP enhanced their confidence in scan interpretation. Conclusion: While no statistically significant differences were found in accuracy or confidence levels, MIP reconstructions showed promise in enhancing correct detection rates and expediting case evaluations, especially among senior residents. The majority of participants expressed strong confidence enhancement due to MIP usage.

BackgroundPrimary intraventricular hemorrhage (IVH) or IVH secondary to intracerebral (ICH) and subarachnoid hemorrhage (SAH) are known to have a very poor prognosis, with an expected mortality between 50 and 80% (Hinson et al. Current Neurology and Neuroscience Reports 10:73–82, 2010). Clearance of IVH might improve patient outcome.MethodsThe study is designed as an investigator-initiated, comparative, prospective, multi-center, 1:1 randomized phase 2 trial evaluating the efficacy and safety of active irrigation in external ventricular drainage (intervention arm—IRRAflow) compared to passive external ventricular drainage (control arm—EVD).The trial will enroll 58 patients with primary or secondary IVH. Major eligibility criteria include age ≥18 years of age, IVH documented on head CT or MRI scan (Graeb score ≥3), need of cerebrospinal fluid drainage, deterioration of consciousness or medical sedation at the time of enrollment, and indication for active treatment evaluated by the treating physicians. Exclusion criteria included patients with fixed and dilated pupils and pregnant or nursing women.The primary endpoint of the study is catheter occlusion evaluated by time to first observed occlusion from VC placement. Secondary endpoints include clearance of ventricular blood as measured by head CT scan, rates of catheter-related infection and shunt dependency, length of intensive care unit stay, functional status—Extended Glascow Outcome Scale (eGOS) and modified Rankin scale (mRS) at discharge to rehabilitation and 90 days—and mortality rates at 30 days and 90 days.DiscussionWith no standardized treatment for IVH and a poor prognosis, new treatments are needed. IVH patients often need CSF drainage to treat hydrocephalus and to decrease ICP. Standard treatment with passive external ventricular drainage is related to an increased risk of infections which is found in up to 22% of treated cases. The passive VC is known to have a risk of occlusion and is seen in 19–47% of the cases.We hypothesize that the use of active fluid change using the IRRAflow system will be safe and feasible and will reduce the occlusion and infection rates in patients with IVH.Trial registrationClicalTrials.gov NCT05204849. Registered 15 December 2021. Updated 24 January 2022

To characterize variations among pediatric emergency physicians and their hospital facilities regarding sedation of the uncooperative, stable child for head CT following closed head injury. Mail survey with two follow-up mailings. Surveys were sent to all members of the Emergency Medicine Section of the American Academy of Pediatrics (AAP). Of 596 surveys sent, 431 (72%) were returned, with 304 (51%) usable responses. Respondents annually sedate over 17,500 children for post-traumatic head CT. Formal training to sedate children for head CT was noted by 73%. Published guidelines for sedation are followed by 74%; 10% were unaware of the existence of published guidelines for sedation. Twenty-six percent of the respondents were very or somewhat dissatisfied with their sedation-related practices. In response to three clinical scenarios involving sedation of 8-month-old, 3-year-old, and 6-year-old children for head CT, midazolam was the most commonly chosen drug. Over 20 different sedation strategies were selected for each scenario. Sedation practices for post-traumatic pediatric head CT vary widely, among both physicians and individual practitioners. Institutional and individual sedation-relation policies vary widely as well. Variation and dissatisfaction with sedation practices may reflect uncertainty regarding optimal sedation strategies. Further cost-effectiveness research is necessary.