A low-cost density reference phantom for computed tomography.
Ontology highlight
ABSTRACT:
SUBMITTER: Levine ZH
PROVIDER: S-EPMC2673671 | biostudies-other | 2009 Feb
REPOSITORIES: biostudies-other
Similar Datasets
Project description:In this article, a heterogeneous multimodal anthropomorphic breast phantom with carcinoma is introduced to meet the response of the natural breast tissue when imaged using ionizing and non-ionizing machines. The skin, adipose, fibroglandular, pectoral muscle, and carcinoma tissue were mimicked. A T1-weighted breast magnetic resonance image with BI-RADS I tissue segmentation was used for molds creation. The tissue-mimicking materials (TMMs) were tailored in terms of their elemental composition weight fractions and their response to ionization radiation parameters. These are the mass attenuation coefficient (MAC), electron density (ne) and effective atomic number (Zeff). The behaviour of the TMMs, when exposed to a wide range of ionization radiation energy, was investigated analytically and numerically using X-COM. The achieved results showed an excellent agreement with the corresponding properties of the natural breast elemental compositions as reported by the International Commission on Radiation Units and Measurements (ICRU). The MAC of the TMMs and the ICRU-based breast tissue were found to be consistent. The maximum percentage of error in ne and Zeff amounts to only 2.93% and 5.76%, respectively. For non-ionizing imaging, the TMMs were characterized in term of T1 and T2 relaxation times. Using our preclinical MRI unit, the TMMs relaxation times were measured and compared to the natural tissue. The fabricated phantom was validated experimentally using CT, MRI, and Mammographic machines. The achieved images of the TMMs were in alignment with the real tissue in terms of CT HU values and grayscale colors. T1W and T2W images on MRI revealed the expected contrast between TMMs as in natural tissue.
| S-EPMC10101397 | biostudies-literature
Project description:ObjectivesCalcific and hemorrhagic intracranial lesions with attenuation levels of less than 100 Hounsfield units (HUs) cannot currently be reliably differentiated by single-energy computed tomography (SECT). The proper differentiation of these lesion types would have a multitude of clinical applications. A phantom model was used to test the ability of dual-energy CT (DECT) to differentiate such lesions.Materials and methodsAgar gel-bound ferric oxide and hydroxyapatite were used to model hemorrhage and calcification, respectively. Gel models were scanned using SECT and DECT and organized into SECT attenuation-matched pairs at 16 attenuation levels between 0 and 100 HU. Dual-energy CT data were analyzed using 3-dimensional (3D) Gaussian mixture models (GMMs), as well as a simplified threshold plane metric derived from the 3D GMM, to assign voxels to hemorrhagic or calcific categories. Accuracy was calculated by comparing predicted voxel assignments with actual voxel identities.ResultsWe measured 6032 voxels from each gel model, for a total of 193,024 data points (16 matched model pairs). Both the 3D GMM and its more clinically implementable threshold plane derivative yielded similar results, with higher than 90% accuracy at matched SECT attenuation levels of 50 HU and greater.ConclusionsHemorrhagic and calcific lesions with attenuation levels between 50 and 100 HU were differentiable using DECT in a clinically relevant phantom system with higher than 90% accuracy. This method warrants further testing for potential clinical applications.
| S-EPMC4335714 | biostudies-literature
Project description:The regular evaluation of imaging performance of computed tomography (CT) scanners is essential for CT quality assurance. For automation of this process, the software QAMaster was developed at the Universitätsklinikum Erlangen, which provides based on CT scans of the CatPhan® 504 (The Phantom Laboratory, Salem, USA) automated image quality analysis and documentation by evaluating CT number accuracy, spatial linearity, uniformity, contrast-noise-ratio, spatial resolution, noise, and slice thickness. Dose assessment is supported by calculations of the weighted computed tomography dose index (CTDIw ) and weighted cone beam dose index (CBDIw ). QAMaster was tested with CatPhan® 504 scans and compared to manual evaluations of these scans, whereby high consistency of the respective results was observed. The CT numbers, spatial linearity, uniformity, contrast-noise-ratio, noise, and slice thickness deviated by only (0.13 ± 0.25) HU, (0.02 ± 0.05) mm, (-0.01 ± 0.03)%, 0.8 ± 1.8, (0.131 ± 0.05) HU, and (0.004 ± 0.005) mm between both evaluations, respectively. The QAMaster results for spatial resolution did not differ significantly (p = 0.34) from the CatPhan® 504 based manual resolution assessment. Dose computations were fully consistent between QAMaster and manual calculations. Thus, QAMaster proved to be a comprehensive and functional software for performing an automated CT quality assurance routine. QAMaster will be open-source after its release.
| S-EPMC8992959 | biostudies-literature
Project description: Not available
| S-EPMC11007503 | biostudies-literature
Project description:BackgroundThe aim of this study was to compare the dose reduction potential and image quality of deep learning-based image reconstruction (DLIR) with those of filtered back-projection (FBP) and iterative reconstruction (IR) and to determine the clinically usable dose of DLIR for low-dose chest computed tomography (LDCT) scans.MethodsMulti-slice computed tomography (CT) scans of a chest phantom were performed with various tube voltages and tube currents, and the images were reconstructed using seven methods to control the amount of noise reduction: FBP, three stages of IR, and three stages of DLIR. For subjective image analysis, four radiologists compared 48 image data sets with reference images and rated on a 5-point scale. For quantitative image analysis, the signal to noise ratio (SNR), contrast to noise ratio (CNR), nodule volume, and nodule diameter were measured.ResultsIn the subjective analysis, DLIR-Low (0.46 mGy), DLIR-Medium (0.31 mGy), and DLIR-High (0.18 mGy) images showed similar quality to the FBP (2.47 mGy) image. Under the same dose conditions, the SNR and CNR were higher with DLIR-High than with FBP and all the IR methods (all P<0.05). The nodule volume and size with DLIR-High were significantly closer to the real volume than with FBP and all the IR methods (all P<0.001).ConclusionsDLIR can improve the image quality of LDCT compared to FBP and IR. In addition, the appropriate effective dose for LDCT would be 0.24 mGy with DLIR-High.
| S-EPMC10006148 | biostudies-literature
Project description:PURPOSE:To compare the diagnostic performance and raters´confidence of radiography, radiography equivalent dose multi-detector computed tomography (RED-MDCT) and radiography equivalent dose cone beam computed tomography (RED-CBCT) for finger fractures. METHODS:Fractures were inflicted artificially and randomly to 10 cadaveric hands of body donors. Radiography as well as RED-MDCT and RED-CBCT imaging were performed at dose settings equivalent to radiography. Images were de-identified and analyzed by three radiologists regarding finger fractures, joint involvement and confidence with their findings. Reference standard was consensus reading by two radiologists of the fracturing protocol and high-dose multi-detector computed tomography (MDCT) images. Sensitivity and specificity were calculated and compared with Cochrane´s Q and post hoc analysis. Rater´s confidence was calculated with Friedman Test and post hoc Nemenyi Test. RESULTS:Rater´s confidence, inter-rater correlation, specificity for fractures and joint involvement were higher in RED-MDCT and RED-CBCT compared to radiography. No differences between the modalities were found regarding sensitivity. CONCLUSION:In this phantom study, radiography equivalent dose computed tomography (RED-CT) demonstrates a partly higher diagnostic accuracy than radiography. Implementing RED-CT in the diagnostic work-up of finger fractures could improve diagnostics, support correct classification and adequate treatment. Clinical studies should be performed to confirm these preliminary results.
| S-EPMC6400385 | biostudies-literature
Project description:Age-related loss of muscle mass and function (sarcopenia) is linked to poor outcomes after operation and trauma. Here we evaluate computed tomography measured psoas muscle density and area using quick and simple tools available to the bedside clinician. We hypothesize these measures will predict poor outcomes after blunt traumatic injury.We conducted a retrospective cohort study of patients ages ?45 years in the Ohio State University Trauma Registry in 2008 that received a computed tomographic scan of the abdomen and/or pelvis with intravenous contrast. Psoas Index and Hounsfield unit average calculation were measured at the L3 level. In the study, 90-day mortality, complication, duration of stay ?7 days, and dependent discharge were compared with Psoas Index and Hounsfield unit average calculation.In the study, 151 patients met the inclusion criteria. Patients were stratified into interquartile ranges based either on Psoas Index or Hounsfield unit average calculation values. After adjustment with sex-specific cutoffs, the lowest interquartile range of Psoas Index was associated with 90-day mortality (relative risk [RR] 5.95, P < .008), but did not reach significance in other outcomes. The lowest interquartile range of Hounsfield unit average calculation was associated with 90-day mortality (RR 5.95, P < .008), duration of stay ? 7 days (RR 1.63, P = .048), complication risk (RR 2.30, P = .002), and dependent discharge 2.14, P = .015).Psoas muscle density is a significant predictor of poor outcomes after traumatic injury. This objective, quick, and readily available measure of sarcopenia can identify patients requiring aggressive nutritional and physical therapy to improve prognosis, prevent recurrent traumatic injury, and aid in discharge planning.
| S-EPMC5893151 | biostudies-literature
Project description:The Lung Computed Tomography Screening Reporting and Data System (Lung-RADS) reduces the false-positive rate of lung cancer screening but introduces prolonged periods of uncertainty for indeterminate findings. We assess the cost-effectiveness of a screening program that assesses indeterminate findings earlier via a hypothetical diagnostic biomarker introduced in place of Lung-RADS 3 and 4A guidelines. We evaluated the performance of the US Preventive Services Task Force (USPSTF) recommendations on lung cancer screening with and without a hypothetical noninvasive diagnostic biomarker using a validated microsimulation model. The diagnostic biomarker assesses the malignancy of indeterminate nodules, replacing Lung-RADS 3 and 4A guidelines, and is characterized by a varying sensitivity profile that depends on nodules' size, specificity, and cost. We tested the robustness of our findings through univariate sensitivity analyses. A lung cancer screening program per the USPSTF guidelines that incorporates a diagnostic biomarker with at least medium sensitivity profile and 90% specificity, that costs $250 or less, is cost-effective with an incremental cost-effectiveness ratio lower than $100 000 per quality-adjusted life year, and improves lung cancer-specific mortality reduction while requiring fewer screening exams than the USPSTF guidelines with Lung-RADS. A screening program with a biomarker costing $750 or more is not cost-effective. The health benefits accrued and costs associated with the screening program are sensitive to the disutility of indeterminate findings and specificity of the biomarker, respectively. Lung cancer screening that incorporates a diagnostic biomarker, in place of Lung-RADS 3 and 4A guidelines, could improve the cost-effectiveness of the screening program and warrants further investigation.
| S-EPMC8564700 | biostudies-literature
Project description:BackgroundComputed tomography (CT) analysis of body composition has garnered interest as a potential prognostic tool in those with cancer. A range of pre-defined thresholds currently exist within the literature to define low skeletal muscle mass and density. The aim of the present systematic review was to assess the prevalence of low skeletal muscle index (SMI) and density (SMD) within the literature, across a range of common solid tumours.MethodsA systematic search of PubMed was carried out to identify studies reporting CT analysis of SMI and SMD in patients with colorectal, oesophageal, gastric, hepatobiliary, pancreatic, breast, and lung cancer. The type of cancer, whether curative or non-curative disease, the anthropomorphic parameter studied, threshold used to define low SMI and SMD, and the prevalence of these anthropomorphic measurements within the population were recorded.ResultsOf the 160 studies included, 156 reported an assessment of SMI and 35 reported assessment of SMD. The median prevalence of low SMI was 43% (30.1-57.1) and low SMD 49.4% (31.7-58.5) across the entire cohort. There was little variation in the prevalence of low SMI and SMD when studies were divided into curative and non-curative cohorts-40.7% (27.5-51.3) vs. 48.4% (30.9-60.1) and 37.8% (32.2-52.2) vs. 55.3% (38.5-64.7) respectively. When divided into colorectal, oesophageal, gastric, hepatobiliary, pancreatic, breast and lung cancers, similar prevalence of low SMI (46.0% %, 49.8%, 35.7%, 41.1%, 32.3%, 34%, and 49.5%) and low SMD were also observed (52.1%, 54.3%, 71.2%, 56.8%, 55.3%, and 52.6%). This was maintained when studies were stratified into cohorts by threshold used-low SMI (Martin 48.9%, Prado 49.9%, and Others 36.0%) and low SMD (Martin 52.4% and Others 48.6%).ConclusionsLow SMI and SMD are endemic across a range of cancer types and disease stage, challenging pre-existing dogma of the determinants of prevalence.
| S-EPMC8718024 | biostudies-literature
Project description:Objective Computed tomography (CT) can be used for visualizing acute intracerebral hemorrhages (ICHs) as distinct hyperdense areas and cerebral edema as perihematomal low-density areas (LDAs). We observed a perihematomal LDA on CT, which appeared to be part of a hemorrhage on magnetic resonance imaging (MRI) in acute ICH. We named this "CT perihematomal rim" and evaluated its characteristics and clinical significance. Methods We stratified patients with acute ICH according to the presence or absence of a CT perihematomal rim and then compared their radiologic findings. Logistic regression analyses were performed to assess whether the CT findings can predict the presence of a CT perihematomal rim. Patients Patients within 24 hours of ICH onset who were admitted between September 1, 2014, and October 31, 2018, were registered. Results Overall, 139 patients (91 men; mean age, 66 years) were investigated. CT perihematomal rims were observed in 40 patients (29%). ICH volumes on CT were 30% smaller than those on MRI in patients with CT perihematomal rims. On a multivariate analysis, the presence of a CT perihematomal rim was independently associated with the maximum diameter of the perihematomal LDA. According to a receiver operating characteristic analysis, the maximum LDA diameter threshold was 7.5 mm (sensitivity, 85%; specificity, 83%). Conclusion CT perihematomal rims were observed in 29% of the patients with acute ICH. A perihematomal LDA (>7.5 mm) in acute ICH cases should be considered a CT perihematomal rim. Clinicians should be aware that the ICH volume on CT may be underestimated by 30%.
| S-EPMC8381191 | biostudies-literature