Computed Tomography Protocol Research Articles

Analysis of the Relationship between Image Noise Value and Computed Tomography Dose Index (CTDI) on Pitch Variation of Routine Abdominal CT Protocol at Koja Regional Hospital, North Jakarta

Computed Tomography (CT) has become one of the primary diagnostic methods in modern medicine, allowing detailed and accurate visualization of the internal structures of the human body. In its use, the pitch value can affect the radiation dose received by the patient and the quality of the resulting image. This study aims to analyze the effect of pitch variations on the Computed Tomography Dose Index (CTDI) and image noise in Routine Abdominal CT to achieve the best image quality with minimal patient dose. This research method uses a quantitative design using a 32 cm diameter PMMA water phantom as a model. Eight pitch variations (0.40, 0.55, 0.60, 0.80, 0.90, 1.00, 1.35, and 1.50) were evaluated using a Siemens Somatom Perspective 128 Slice CT-Scan. Data were collected through experiments on the water phantom and analyzed using descriptive analysis, normality tests, and correlation tests. The results showed no significant relationship between CTDI values and image noise with pitch variations. Increasing the pitch value contributed to increasing CTDI but decreased image noise. These results indicate that a pitch of 0.60 has an optimal image noise value and minimal CTDI in the Routine CT Abdomen protocol at RSUD Koja, North Jakarta. This study provides a deeper understanding of the importance of selecting the correct pitch value in minimizing patient radiation dose while maintaining good image quality. The practical implication is using a pitch of 0.60 as the optimal value for the Routine CT Abdomen protocol, which can reduce the risk of excessive radiation exposure to patients. Keywords: CT-Scan, pitch, water phantom, CT Abdomen, noise, computed tomography dose index (CTDI)

Higher Validity, Lower Radiation: A New Ictal Single-Photon Emission Computed Tomography Framework.

To assess whether arterial spin labeling perfusion images of healthy controls can enhance ictal single-photon emission computed tomography analysis and whether the acquisition of the interictal image can be omitted. We developed 2 pipelines: The first uses ictal and interictal images and compares these to single-photon emission computed tomography and arterial spin labeling of healthy controls. The second pipeline uses only the ictal image and the analogous healthy controls. Both pipelines were compared to the gold standard analysis and evaluated on data of individuals with epilepsy who underwent ictal single-photon emission computed tomography imaging during presurgical evaluation between 2010 and 2022. Fifty healthy controls prospectively underwent arterial spin labeling imaging. The correspondence between the detected hyperperfusion and the postoperative resection cavity or the presumably affected lobe was assessed using Dice score and mean Euclidean distance. Additionally, the outcomes of the pipelines were automatically assigned to 1 of 5 concordance categories. Inclusion criteria were met by 43 individuals who underwent epilepsy surgery and by 73 non-surgical individuals with epilepsy. Compared to the gold standard analysis, both pipelines resulted in significantly higher Dice scores and lower mean distances (p < 0.05). The combination of both provided localizing results in 85/116 cases, compared to 54/116 generated by the current gold standard analysis and the ictal image alone produced localizing results in 60/116 (52%) cases. We propose a new ictal single-photon emission computed tomography protocol; it finds relevantly more ictal hyperperfusion, and halves the radiation dose in about half of the individuals. ANN NEUROL 2024;96:1160-1173.

The Effect of Low-Dose CT Protocols on Shoulder Model-Based Tracking accuracy Using Biplane Videoradiography.

Model-based tracking is being increasingly used to quantify shoulder kinematics and typically employs computed tomography (CT) to create the 3D bone volumes, which adds to the total radiation exposure. Lower-dose CT protocols may be possible given the contrast between bone and the surrounding soft tissues. The purpose of this study was to describe the dose-accuracy tradeoff between low-dose CT scans and the kinematic tracking accuracy of the humerus, scapula, and clavicle when tracked using an intensity-based registration algorithm. Three fresh-frozen cadavers consisting of the torso and bilateral shoulders were tested. The CT protocols investigated included a full-dose protocol and 4 experimental low-dose protocols that modulated x-raytube current and peak voltage. Bead-based tracking (i.e., radiostereometric analysis) served as the reference standard to which model-based tracking results were compared. Accuracy was described in terms of both segmental (humerus, scapula, and clavicle) and joint (glenohumeral, acromioclavicular) kinematics using root-mean-square (RMSE), bias, precision, and worst-case errors. The low-dose CT scans resulted in an average dose reduction of 70.6-92.8%. RMSEs tended to increase as CT dose decreased with average glenohumeral errors increasing from 0.5° and 0.6 mm to 0.6° and 0.6 mm between the highest and lowest-dose protocols, and average acromioclavicular errors increasing from 0.6° and 0.8 mm to 0.7° and 0.9 mm. However, the difference in joint kinematic errors between the highest and lowest-dose CT scanning protocols was generally small (≤0.3°, ≤ 0.1 mm). It is possible to substantially reduce the CT dose associated with shoulder motion analysis using biplane videoradiography without significantly impacting data fidelity.

Development of a user-friendly calculator for a pediatric split-bolus polytrauma computed tomography protocol

We present here a user-friendly calculator for the setting of a pediatric split-bolus polytrauma computed tomography (CT) protocol with a mixed arterial and venous phase, aiming to both reduce radiation dose and improve workflow while assuring optimal image quality. All the different parameters are calculated based on patient’s weight with rapid computation of the injected contrast media and saline volumes, injection’s flow rate, injection’s timing, and optimal acquisition time. The designed calculator is built in a widely available Google Sheets file, accessible by a quick response (QR) code. Although polytrauma imaging represents the main goal of the technique, it can be used in a wide variety of contexts, including oncological, infectious, and vascular pathologies.Graphical

The overview of imaging protocols for chest CT

Computed Tomography (CT) is a common method of choice in the diagnosis of thoracic diseases. Since CT operates on the principle of ionizing radiation and frequently involves the use of contrast agents, it is crucial to standardize CT protocols to reduce the need for repeat imaging and, consequently, minimize patient exposure to radiation. The selection of a CT protocol primarily depends on the patient’s clinical indications and needs. The main classification of CT protocols distinguishes between the use of contrast agents (CECT) and non-contrast protocols (NCCT). The LDCT protocol is characterized by a low radiation dose and high sensitivity for detecting pulmonary nodules, making it suitable for lung cancer screening. Ultra-LDCT yields satisfactory results in diagnosing pneumonia and pneumothorax. Cine CT enables the assessment of cardiac function throughout the entire cardiac cycle, though it involves a high radiation dose and low temporal resolution. The use of contrast agents is particularly beneficial for differentiating adjacent non-vascular structures, more accurately identifying vascular anatomy, and improving the detection and characterization of pathological lesions. For diagnosing vascular pathologies, CTA is used, while CTPA is essential for diagnosing pulmonary embolism (PE) with high sensitivity and specificity. TRO CT is useful in cases of acute chest pain to rule out emergencies. Dynamic changes in tissue perfusion are monitored with DCE-CT, which is also valuable in tumor diagnostics. In pediatric applications of CT for the chest, it is essential to emphasize the use of the lowest possible radiation dose and contrast agent to minimize risks.

Factors affecting radiation exposure in patients undergoing endoscopic treatment for urolithiasis.

Imaging techniques, such as computed tomography (CT) and fluoroscopy, are essential for the diagnosis and treatment of urolithiasis. There is increasing concern regarding the cumulative radiation dose associated with medical imaging and its adverse effects. This study aimed to assess radiation exposure in patients undergoing endoscopic management of urolithiasis and to identify factors associated with increased exposure.A retrospective analysis of all consecutive symptomatic urolithiasis cases who underwent endoscopic surgery over a two-year period at a tertiary referral center was performed. The cumulative radiation dose was recorded per stone episode, and the effective dose (ED) then calculated. Multivariable regression analysis was performed to determine the association between ED and patient, stone, and procedural characteristics.Between January 2020 and December 2021, 250 patients underwent endoscopic intervention for urolithiasis; 71% (n = 178) were male with a median age of 48 years (IQR 35-59). The median stone size was 6mm (IQR, 5-8mm) and the median stone volume was 110 mm3 (IQR, 60-206 mm3). Most stones were located in the distal ureter (46%, n = 114). The median ED received per stone episode was 3.99 mSv (IQR 2.9-7 mSv). On multivariable analysis, BMI, number of CT scans performed, CT protocol used, and repeat procedures strongly predicted increased radiation dose (p < 0.01).It is important for urologists to consider the cumulative radiation dosage in patients with urolithiasis. Strategies to minimize exposure, such as avoiding re-imaging, low-dose CTs, and collimation of the region of interest with judicious magnification, should be considered during treatment.

Development, validation, and application of a generic image-based noise addition method for simulating reduced dose computed tomography images.

Major efforts in computed tomography (CT) have been focused on reducing radiation dose to patients while maintaining adequate diagnostic quality. To that end, research tools have been developed to simulate reduced-dose images via either image-based or projection-based methods. The former is limited to fully capturing realistic texture, streak, and non-stationary characteristics of reduced dose, while the latter is impractical clinically. To develop and validate an image-based noise addition method that accounts for such attributes while being practical in clinical settings. A noise addition method was developed to add realistic noise in the image domain. The method first estimates the noise power spectrum (NPS) of CT images, which are also forward-projected to form synthetic projections. The projection data are supplemented with random white noise proportional to their attenuation values. The noise sinogram is then back-projected onto the image, filtered by the NPS, and scaled according to the desired dose reduction level. The tool was evaluated using both phantom images and patient data. The phantom images were acquired using a multi-sized image quality phantom (Mercury Phantom 3.0, Duke University), and a thorax anthropomorphic phantom (Lungman Phantom, Kyoto Kagaku) at different dose levels and reconstruction settings. The patient images consisted of two dose levels of various CT examinations and reconstruction settings. The simulated and real reduced-dose images were compared in terms of the noise magnitude and texture (i.e., NPS average frequency, NPS-fav). The utility of this methodology was also assessed for routine clinical use for CT protocol review. For the phantom images, the percent errors in the noise magnitude between the simulated images and the actual images of the Mercury Phantom and anthropomorphic phantom images were 3.34% and 3.50%, respectively. The difference in fav was 0.07mm-1 for the Mercury Phantom and 0.06mm-1 for the anthropomorphic phantom between the simulated and actual images. The average noise magnitude percent error between the simulated and actual patient images was 4.61% with noise texture judged to be visually comparable with some kernel dependencies. When implemented clinically, the tool proved practical to simplify the process of estimating radiation dose reduction for CT protocols, resulting in a 50% dose reduction of our multiple myeloma protocol. The method generated simulated CT images with realistic noise properties similar to images acquired at the same radiation exposure without needing access to raw projection data.

Less Dose, Same Care: Evaluating Computed Tomography Utilization for Pediatric Appendicitis

BackgroundAn ultrasonography-first, magnetic resonance imaging-second protocol, and attention to dose reduction was implemented to reduce computed tomography rates for appendicitis at our institution. We aimed to compare current computed tomography usage and report radiation doses at our children's associated system hospitals and referring nonsystem hospitals. MethodsA retrospective study of pediatric patients who underwent appendectomy and had a preoperative computed tomography scan between June 2020 and June 2023 was performed. Demographics and imaging details were abstracted from the medical record. Size-specific dose estimates and effective dose estimates were calculated for each computed tomography. Size-specific dose estimates were compared with American College of Radiology Dose Index Registry diagnostic reference levels. ResultsOf 1,419 patients, 409 (29%) received a computed tomography for appendicitis, a 56% reduction from previous years (2012–2015) (P < .001). Overall, 352 computed tomography scans had dose data available, of which 291 (83%) were performed at system hospitals and 61 (17%) at nonsystem hospitals. The median size-specific dose estimate per computed tomography was 11.0 mGy (interquartile range 7.0, 17.4) for nonsystem hospitals and 9.1 mGy (interquartile range 6.6, 14.0) for system hospitals. The median effective dose per computed tomography was 6.7 mSv (interquartile range 4.3, 12.9) at nonsystem hospitals and 5.1 mSv (interquartile range 3.3, 9.4) at system hospitals. Nienty-three (n = 273) computed tomography scans performed at system hospitals and 30 computed tomography scans (n = 61) at nonsystem hospitals exceeded American College of Radiology Dose Index Registry age-based diagnostic reference levels. ConclusionThe ultrasonography-first, magnetic resonance imaging–second protocol resulted in a significant decrease in computed tomography use for appendicitis diagnosis. Comparison of doses to American College of Radiology Dose Index Registry reference levels suggests that computed tomography protocol optimization may allow for dose reduction at some facilities.

Novel intravascular tantalum oxide-based contrast agent achieves improved vascular contrast enhancement and conspicuity compared to Iopamidol in an animal multiphase CT protocol

BackgroundTo assess thoracic vascular computed tomography (CT) contrast enhancement of a novel intravenous tantalum oxide nanoparticle contrast agent (carboxybetaine zwitterionic tantalum oxide, TaCZ) compared to a conventional iodinated contrast agent (Iopamidol) in a rabbit multiphase protocol.MethodsFive rabbits were scanned inside a human-torso-sized encasement on a clinical CT system at various scan delays after intravenous injection of 540 mg element (Ta or I) per kg of bodyweight of TaCZ or Iopamidol. Net contrast enhancement of various arteries and veins, as well as image noise, were measured. Randomized scan series were reviewed by three independent readers on a clinical workstation and assessed for vascular conspicuity and image artifacts on 5-point Likert scales.ResultsOverall, net vascular contrast enhancement achieved with TaCZ was superior to Iopamidol (p ≤ 0.036 with the exception of the inferior vena cava at 6 s (p = 0.131). Vascular contrast enhancement achieved with TaCZ at delays of 6 s, 40 s, and 75 s was superior to optimum achieved Iopamidol contrast enhancement at 6 s (p ≤ 0.036. Vascular conspicuity was higher for TaCZ in 269 of 300 (89.7%) arterial and 269 of 300 (89.7%) venous vessel assessments, respectively (p ≤ 0.005), with substantial inter-reader reliability (κ = 0.61; p < 0.001) and strong positive monotonic correlation between conspicuity scores and contrast enhancement measurements (ρ = 0.828; p < 0.001).ConclusionTaCZ provides absolute and relative contrast advantages compared to Iopamidol for improved visualization of thoracic arteries and veins in a multiphase CT protocol.Relevance statementThe tantalum-oxide nanoparticle is an experimental intravenous CT contrast agent with superior cardiovascular and venous contrast capacity per injected elemental mass in an animal model, providing improved maximum contrast enhancement and prolonged contrast conspicuity. Further translational research on promising high-Z and nanoparticle contrast agents is warranted.Key PointsThere have been no major advancements in intravenous CT contrast agents over decades.Iodinated CT contrast agents require optimal timing for angiography and phlebography.Tantalum-oxide demonstrated increased CT attenuation per elemental mass compared to Iopamidol.Nanoparticle contrast agent design facilitates prolonged vascular conspicuity.Graphical

Low-dose high-resolution chest CT in adults with cystic fibrosis: intraindividual comparison between photon-counting and energy-integrating detector CT

BackgroundRegular disease monitoring with low-dose high-resolution (LD-HR) computed tomography (CT) scans is necessary for the clinical management of people with cystic fibrosis (pwCF). The aim of this study was to compare the image quality and radiation dose of LD-HR protocols between photon-counting CT (PCCT) and energy-integrating detector system CT (EID-CT) in pwCF.MethodsThis retrospective study included 23 pwCF undergoing LD-HR chest CT with PCCT who had previously undergone LD-HR chest CT with EID-CT. An intraindividual comparison of radiation dose and image quality was conducted. The study measured the dose-length product, volumetric CT dose index, effective dose and signal-to-noise ratio (SNR). Three blinded radiologists assessed the overall image quality, image sharpness, and image noise using a 5-point Likert scale ranging from 1 (deficient) to 5 (very good) for image quality and image sharpness and from 1 (very high) to 5 (very low) for image noise.ResultsPCCT used approximately 42% less radiation dose than EID-CT (median effective dose 0.54 versus 0.93 mSv, p < 0.001). PCCT was consistently rated higher than EID-CT for overall image quality and image sharpness. Additionally, image noise was lower with PCCT compared to EID-CT. The average SNR of the lung parenchyma was lower with PCCT compared to EID-CT (p < 0.001).ConclusionIn pwCF, LD-HR chest CT protocols using PCCT scans provided significantly better image quality and reduced radiation exposure compared to EID-CT.Relevance statementIn pwCF, regular follow-up could be performed through photon-counting CT instead of EID-CT, with substantial advantages in terms of both lower radiation exposure and increased image quality.Key PointsPhoton-counting CT (PCCT) and energy-integrating detector system CT (EID-CT) were compared in 23 people with cystic fibrosis (pwCF).Image quality was rated higher for PCCT than for EID-CT.PCCT used approximately 42% less radiation dose and offered superior image quality than EID-CT.Graphical

Urinary stone assessment in a single-phase may replace the unenhanced and multiphase computed tomography protocol in painless visible haematuria.

Painless visible haematuria (VH) necessitates a computed tomography (CT) usually consisting of one unenhanced and two to three contrast enhanced acquisitions to detect urinary tract stones and malignancy. Recently, we demonstrated that a single nephrographic phase (NP) CT sufficed in detecting malignancy in patients with painless VH. Now, we aim to evaluate the diagnostic performance of single NP CT in stone detection and size measurements in the same cohort. "A Prospective Trial for Examining Haematuria using Computed Tomography" (PROTEHCT) was a single-center prospective diagnostic study in patients with painless VH between September 2019 and June 2021. All underwent four-phase CT (reference standard) from which a single NP CT (experimental) was extracted. Two randomised readers independently assessed the experimental CT for urinary stones and size. Statistical analysis included diagnostic accuracies and inter-reader agreement (kappa) of experimental CT, and size correlation (Spearman's ρ) between experimental CT and reference standard. In 308 included patients (median age: 68 years, 250 males), urinary stones (median size 5 mm) were diagnosed in 21%. The per-patient experimental CT sensitivity was 86% (97% for stones ≥ 5 mm), specificity was 98% and accuracy was 96%. The experimental CT sensitivity for detecting kidney stones was 78% (89% for stones ≥ 5 mm), and 100% for bladder and ureteral stones. No missed stone required active treatment. The inter-reader agreement was almost perfect (96%, k = 0.85). The correlation in stone size was very strong (ρ = 0.91). Conclusions: A single NP CT is sufficient in detecting and measuring urinary stones in patients with painless VH.

Paediatric computed tomography diagnostic reference levels in Africa: A systematic review.

Improvements in computed tomography (CT) technology in terms of image quality and reduction in absorbed dose have increased its applications in medical imaging. Diagnostic reference levels (DRLs) help to identify high radiation doses that are unusually delivered to patients undergoing exposure to ionising radiation. The aim of this review was to provide an overview of published studies by African researchers towards establishing paediatric CT DRLs in Africa. The search for articles was conducted using some relevant literature search engines including PubMed, Scopus, Science Direct, Google Scholar and Web of Science. Two reviewers were involved in the article selection process which involved a three-stage screening process of identifying; article titles, abstracts and full-test reading. One hundred and seventy-four articles were identified from the database, PubMed (30), Scopus (21), Google Scholar (53), Web of Science (25) and Science Direct (45). Fifty duplicated articles were excluded before screening. Twelve peer-reviewed articles were included in this study based on the inclusion criteria. DRL values in terms of computed tomography dose index volume of head for the age groupings 0-1, 1-5, 5-10 and 10-15 were 27, 36.6, 39.5 and 47.5 mGy while the dose length product values were 461.6, 664, 872 and 978 mGy.cm respectively. The DRLs were calculated as 75th percentile of the local DRLs reported by the 12 articles included in this review. This review has shown that only few of the African countries (19%) have published studies on paediatric CT DRLs. There were variations in the DRLs published by the various authors which indicate that harmonisation and standardisation of paediatric CT protocols is essential for the optimisation of paediatric doses.

Comparison of virtual and true non-contrast images from dual-layer spectral detector computed tomography (CT) in patients with colorectal cancer.

Colorectal cancer (CRC) is commonly assessed by computed tomography (CT), but the associated radiation exposure is a major concern. This study aimed to quantitatively and qualitatively compare the image quality of virtual non-contrast (VNC) images reconstructed from arterial and portal venous phases with that of true non-contrast (TNC) images in patients with CRC to assess the potential of TNC images to replace VNC images, thereby reducing the radiation dose. A total of 69 patients with postoperative pathologically confirmed CRC at the West China Hospital of Sichuan University between May 2022 and April 2023 were enrolled in this cross-sectional study. The CT protocol included the acquisition of TNC images, arterial and portal venous phase images; the VNC images were reconstructed from the two postcontrast phase images. Several parameters, including the CT attenuation value, absolute attenuation error, imaging noise [standard deviation (SD)], signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR), were measured in multiple abdominal structures for both the TNC and VNC images. Two blinded readers assessed the subjective image quality using a five-point scale. Interobserver agreement was evaluated using interclass correlation coefficients (ICCs). The paired t-test and Wilcoxon signed-rank test were used to compare the objective and subjective results between the TNC and VNC images. Individual measurements of radiation doses for the TNC scan and contrast scan protocols were recorded. A total of 2,070 regions of interest (ROIs) of the 69 patients were analyzed. Overall, the VNC images exhibited significantly lower attenuation values and SD values than the TNC images in all tissues, except for the abdominal aorta, portal vein, and spleen. The mean absolute attenuation errors between the VNC and TNC images were all less than 10 Hounsfield units (HU). The percentages of absolute attenuation errors less than 5 and 10 HU in the VNC images from the arterial phase (VNCa) were 78.99% and 97.97%, respectively, while those from the portal venous phase (VNCp) were 81.59% and 96.96%, respectively. The absolute attenuation errors between the TNC and VNCa images were smaller than those between the TNC and VNCp images for tumors [VNCaerror: 2.77, interquartile range (IQR) 1.77-4.22; VNCperror: 3.27, IQR 2.68-4.30; P=0.002]. The SNR values and CNR values in the VNC images were significantly higher than those in the TNC images for all tissues, except for the portal vein and spleen. The image quality was rated as excellent (represented by a score of 5) in the majority of the TNC and VNC images; however, the VNC images scored lower than the TNC images. Eliminating the TNC phase resulted in a reduction of approximately 37.99% in the effective dose (ED). The VNC images provided accurate CT attenuation, good image quality, and lower radiation doses than the TNC images in CRC, and the VNCa images showed minimal differences in the CT attenuation of the tumors.

Acute pancreatitis and computed tomography: Interest of portal venous phase alone in the initial phase.

There are no guidelines in the literature for the use of a computed tomography (CT) protocol in the initial phase of acute pancreatitis (AP). To evaluate the contribution of single portal venous phase CT compared to triple-phase CT protocol, performed in the initial phase of AP for severity assessment. In this retrospective study, a total of 175 patients with acute pancreatitis who underwent initial triple-phase CT protocol (non-contrast, arterial phase, and portal venous phase) between D3 and D7 after the onset of symptoms were included. Analysis of AP severity and complications was independently assessed by two readers using three validated CT severity scores (CTSI, mCTSI, EPIC). All scores were applied to the triple-phase CT protocol and compared to the single portal venous phase. Inter-observer analyses were also performed. No significant difference whatever the severity score was observed after analysis of the single portal venous phase compared with the triple-phase CT protocol (interstitial edematous pancreatitis: CTSI: 2 vs. 2, mCTSI: 2 vs. 2, EPIC: 1 vs. 1; necrotizing pancreatitis: CTSI: 6 vs. 6, mCTSI: 8 vs. 8, EPIC: 5 vs. 5). Inter-observer agreement was excellent (ICC = 0.96-0.99), whatever the severity score. A triple-phase CT protocol performed at the initial phase of AP was no better than a single portal venous for assessing the severity of complications and could lead to a 63% reduction in irradiation.

Geometric accuracy of low-dose CT scans for use in shoulder musculoskeletal research applications

Computed tomography (CT) imaging is frequently employed in a variety of musculoskeletal research applications. Although research studies often use imaging protocols developed for clinical applications, lower dose protocols are likely possible when the goal is to reconstruct 3D bone models. Our purpose was to describe the dose-accuracy trade-off between incrementally lower-dose CT scans and the geometric reconstruction accuracy of the humerus, scapula, and clavicle. Six shoulder specimens were acquired and scanned using 5 helical CT protocols: 1) 120 kVp, 450 mA (full-dose); 2) 120 kVp, 120 mA; 3) 120 kVp, 100 mA; 4) 100 kVp, 100 mA; 5) 80 kVp, 80 mA. Scans were segmented and reconstructed into 3D surface meshes. Geometric error was assessed by comparing the surfaces of the low-dose meshes to the full-dose (gold standard) mesh and was described using mean absolute error, bias, precision, and worst-case error. All low-dose protocols resulted in a >70 % reduction in the effective dose. Lower dose scans resulted in higher geometric errors; however, error magnitudes were generally <0.5 mm. These data suggest that the effective dose associated with CT imaging can be substantially reduced without a significant loss of geometric reconstruction accuracy.

Establishing Diagnostic Reference Levels and Radiation Dose for Pediatric Head Age-Based Using Computed Tomography in Khartoum State

Computed tomography (CT) is a powerful clinical tool for the diagnosis and management of patients, enabling faster and more accurate diagnosis and the avoidance of interventional surgical techniques. A diagnostic reference level (DRL) is a tool used to aid in optimization of protection in the medical exposure of patients for diagnostic and interventional procedures. It is used in medical imaging with ionizing radiation to indicate whether, in routine conditions, the patient dose or administered activity (amount of radioactive material) from a specified procedure is unusually high or low for that procedure. Radiation dosage variance is one of the topics that arise when dealing with CT devices within medical imaging centers. Diagnostic reference levels have not been established in Sudan. The aim of this study is to propose DRLs for CT of the head for 4 pediatric age groups. The 2 levels that this study covers are volume CT dose index based on a 16-cm phantom (CTDIvol [mGy]) and the dose-length products (DLPs [mGy • cm]). These levels were investigated by conducting a survey to 6 healthcare facilities. The survey consists of questions focused on pediatric exposure parameters, CT protocols, and radiation doses for pediatric age groups &lt;1, 1-5, 5-10, and 10-16 years. For the 4 age groups in the 6 facilities that responded, the mean, 25th, 50th, and 75th percentile values of CTDIvol (mGy) for head CT were for infants (&lt;1 year), 21.2, 14.4, 17.6, and 27.0, respectively; for 1-5 years, 36.5, 15.7, 34.5, and 38.1, respectively; for 5- to 10-year group, the CTDIvol was found to be 40, 15.7, 33.5, and 47.6, respectively, and for the last group of 10-16 years, 41.6, 15.7, 37.4, and 58.3, respectively. The corresponding DLP (mGy • cm) for head CT, the mean, 25th, 50th, and 75th percentile values were as follows: for infants (&lt;1 year), 472.9, 326.9, 385.3, and 545.5, respectively; for 1-5 years, 742.9, 509.1, 689.3, and 902.9, respectively; for 5-10 years, 1,130.4, 501.7, 924.2, and 1,667.4, respectively; for 10-16 years, 1,226.4, 595.4, 870.1, and 1,255.3, respectively. The total mean CTDIvol (mGy) was 38.0, and the total mean DLP (mGy · cm) was 1,001.6. These values have been compared with other values from other similar studies; the summary for these comparisons concluded that the majority of CTDIvol 16-cm phantom and DLP 16-cm phantom values for the head were higher than DRLs reported from other studies in other countries. Therefore, for risk reduction, it is necessary to establish DRLs for pediatric CT in Sudan.

CAREdose 4D Application in Brain CT Scan: The Effect on Dose and Image Quality

Purpose: This study aimed to investigate the effect of CAREdose4D on the dose and image quality in Brain Computed Tomography (CT). Materials and Methods: Noise, Signal-to-Noise Ratio (SNR), and Contrast-to-Noise Ratio (CNR) for Gray Matter (GM), White Matter (WM), Cerebrospinal Fluid (CSF), and skull bones were investigated in brain CT scans of 60 patients. In addition, a phantom study was conducted to examine the effect of CAREdose 4D on the same subject in the brain, chest, abdomen, and pelvic CT protocols. Volume CT dose index (CTDIvol) and Dose Length Product (DLP) were recorded for each scan. Data were analyzed by T-test and Mann-Whitney statistical test with a significance level of less than 0.05. Results: The following results were obtained in active and passive modes of CAREdose 4D in brain CT of patients, respectively: CTDIvol, 15.76±3.94 and 16.96±2.14 mGy (p&lt;0.05); DLP, 253.81±84.69 and 252.73±43.26 mGy.cm (p&gt;0.05). There was no significant difference between SNRs and noise of various tissues of the brain (p&gt;0.05) but CNR difference for gray matter, white matter, and cerebrospinal fluid (CSF) was significant (p&lt;0.05). In the phantom study, SNR decreased in the active status of CAREdose 4D for the head in sequential and spiral modes, Chest, abdomen and pelvis by 7%, 84%, 45%, 20%, and 22%, respectively. Conclusion: CAREdose 4D reduces the dose without having an adverse effect on noise and SNR in brain CT scans. It is recommended newbies and untrained technicians to use CAREdose 4D.

Assessing the Stability of Photon-Counting CT: Insights from a Two-Year Longitudinal Study.

Among the advancements in computed tomography (CT) technology, photon-counting computed tomography (PCCT) stands out as a significant innovation, providing superior spectral imaging capabilities while simultaneously reducing radiation exposure. Its long-term stability is important for clinical care, especially longitudinal studies, but is currently unknown. This study sets out to comprehensively analyze the long-term stability of a first-generation clinical PCCT scanner. Over a two-year period, from November 2021 to November 2023, we conducted weekly identical experiments utilizing the same multi-energy CT protocol. These experiments included various tissue-mimicking inserts to rigorously assess the stability of Hounsfield Units (HU) and image noise in Virtual Monochromatic Images (VMIs) and iodine density maps. Throughout this period, notable software and hardware modifications were meticulously recorded. Each week, VMIs and iodine density maps were reconstructed and analyzed to evaluate quantitative stability over time. Spectral results consistently demonstrated the quantitative stability of PCCT. VMIs exhibited stable HU values, such as variation in relative error for VMI 70 keV measuring 0.11% and 0.30% for single-source and dual-source modes, respectively. Similarly, noise levels remained stable with slight fluctuations linked to software changes for VMI 40 and 70 keV that corresponded to changes of 8 and 1 HU, respectively. Furthermore, iodine density quantification maintained stability and showed significant improvement with software and hardware changes, especially in dual-source mode with nominal errors decreasing from 1.44 to 0.03 mg/mL. This study provides the first long-term reproducibility assessment of quantitative PCCT imaging, highlighting its potential for the clinical arena. This study indicates its long-term utility in diagnostic radiology, especially for longitudinal studies.

Low-iodine-dose computed tomography coupled with an artificial intelligence-based contrast-boosting technique in children: a retrospective study on comparison with conventional-iodine-dose computed tomography

BackgroundLow-iodine-dose computed tomography (CT) protocols have emerged to mitigate the risks associated with contrast injection, often resulting in decreased image quality.ObjectiveTo evaluate the image quality of low-iodine-dose CT combined with an artificial intelligence (AI)-based contrast-boosting technique in abdominal CT, compared to a standard-iodine-dose protocol in children.Materials and methodsThis single-center retrospective study included 35 pediatric patients (mean age 9.2 years, range 1–17 years) who underwent sequential abdominal CT scans—one with a standard-iodine-dose protocol (standard-dose group, Iobitridol 350 mgI/mL) and another with a low-iodine-dose protocol (low-dose group, Iohexol 240 mgI/mL)—within a 4-month interval from January 2022 to July 2022. The low-iodine CT protocol was reconstructed using an AI-based contrast-boosting technique (contrast-boosted group). Quantitative and qualitative parameters were measured in the three groups. For qualitative parameters, interobserver agreement was assessed using the intraclass correlation coefficient, and mean values were employed for subsequent analyses. For quantitative analysis of the three groups, repeated measures one-way analysis of variance with post hoc pairwise analysis was used. For qualitative analysis, the Friedman test followed by post hoc pairwise analysis was used. Paired t-tests were employed to compare radiation dose and iodine uptake between the standard- and low-dose groups.ResultsThe standard-dose group exhibited higher attenuation, contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR) of organs and vessels compared to the low-dose group (all P-values < 0.05 except for liver SNR, P = 0.12). However, noise levels did not differ between the standard- and low-dose groups (P = 0.86). The contrast-boosted group had increased attenuation, CNR, and SNR of organs and vessels, and reduced noise compared with the low-dose group (all P < 0.05). The contrast-boosted group showed no differences in attenuation, CNR, and SNR of organs and vessels (all P > 0.05), and lower noise (P = 0.002), than the standard-dose group. In qualitative analysis, the contrast-boosted group did not differ regarding vessel enhancement and lesion conspicuity (P > 0.05) but had lower noise (P < 0.05) and higher organ enhancement and artifacts (all P < 0.05) than the standard-dose group. While iodine uptake was significantly reduced in low-iodine-dose CT (P < 0.001), there was no difference in radiation dose between standard- and low-iodine-dose CT (all P > 0.05).ConclusionLow-iodine-dose abdominal CT, combined with an AI-based contrast-boosting technique exhibited comparable organ and vessel enhancement, as well as lesion conspicuity compared to standard-iodine-dose CT in children. Moreover, image noise decreased in the contrast-boosted group, albeit with an increase in artifacts.Graphical

Clinical and technical challenges associated with CT dose optimization in practice

Radiation burden represents a particular issue in realizing the greater benefits of computed tomography (CT), conceptual dose levels, real-time and offline dose monitoring software being among major efforts towards optimizing the benefit. Here we share technical and clinical challenges faced on a regional scale in implementing such tools in clinical practice. Conceptual dose baselines, although not limited to the diagnostic reference level (DRL), have for CT been based on anatomical body parts such as the head, chest, abdomen etc. The methodology and calculations used in establishing DRLs have nevertheless resulted in wide variability across CT dose indices. Example, DLP based head trauma DRLs have been reported as 556 mGy cm, 753 mGy cm, and 1820 mGy cm. The suggestion is of a need to establish DRLs based on examinations sharing similar objectives, in particular focusing on clinical indications, seeking to reduce the wide dose variations associated with anatomical based DRLs. Implementing this clinically is a challenge, particularly since CT scan acquisition series are not directly linked nor labeled according to clinical indications. Alternatively, clinical indications are more applicable when linked with CT protocols which are saved on the CT console and easily retrieved. Dose variation is also seen with use of the same protocol, scan coverage and number of scan acquisition series being contributing factors. DRLs based on scan acquisition series for every protocol allows better control and elimination of confounding factors.