Computed Tomography Scanning Techniques Research Articles

Efficacy of Tilt-Angle and Low-Dose CT Scan Guidance in Percutaneous plasma Radiofrequency Treatment for Lumbar 5-Sacrum 1 Disc Herniation.

To investigate the application effect of tilt-angle low-dose ComputedTomography (CT) scanning guidance technology in the plasma radiofrequency treatment of lumbar 5-sacrum 1 (L5-S1) intervertebral disc herniation. A total of 43 patients with L5-S1 disc herniation were included in this study and categorized into vertical-angle-guided CT (Group A, n = 21) and tilt-angle-guided CT (Group B, n = 22) groups. Percutaneous plasma L5-S1 disc radiofrequency treatment was administered. The total number of punctures and scans, operation times, and Numerical Rating Scale (NRS) pain scores (preprocedure and 3 and 30 days postprocedure) were documented. Compared with Group A, punctures and scans were fewer in Group B, and the differences were statistically significant (P = 0.0001). Moreover, the CT scan-guided total surgery time was significantly shorter in Group B than in Group A (P = 0.0001). In addition, the NRS score exhibited a statistically significant difference among preprocedure (T0), 3 day postprocedure (T1), and 30 days (T2) in Groups A (P < 0.05). The NRS score exhibited a statistically significant difference between T0 and T1 and between T0 and T2 in Group B (P < 0.05), but not between T1 and T2 in Group B (P = 0.084). At three time points (T0, T1, T2), there was no statistically significant difference between the two groups (P > 0.05). The tilt-angle low-dose CT scanning technique for L5-S1 disc herniation offers the advantages of high efficiency, low damage, and low radiation, and its clinical application is recommended.

The why, who, how, and what of communicating CT radiation risks to patients and healthcare providers.

Computed tomography (CT) has witnessed tremendous growth in utilization. Despite its immense benefits, there is a growing concern from the general public and the medical community about the detrimental consequences of ionizing radiation from CT. Anxiety from the perceived risks associated with CT can deter referring physicians from ordering clinically indicated CT scans and patients from undergoing medically necessary exams. This article discusses various strategies for educating patients and healthcare providers on the benefits and risks of CT scanning and salient techniques for effective communication.

Volumetric Comparison Between CT Scans and Smartphone-Based Photogrammetry in Patients Undergoing Chin Augmentation With Autologous Fat Graft.

The most accurate methods for assessing fat grafted volume, such as computed tomography (CT) scan and magnetic resonance imaging, use 3-dimensional (3D) evaluation of the recipient area. Currently, other measurement techniques such as photogrammetry (compilation of photos) are employed. The aim of the present study was to compare 3D images obtained by CT scan with those obtained by photogrammetry in patients undergoing autogenous fat grafting to the chin. A prospective longitudinal study was undertaken to assess patients undergoing autologous fat grafting to the chin, capturing preoperative and postoperative (6 months) images with CT scan and photogrammetry. Captured images were submitted to 3D reconstruction with Blender image software. A total of 40 patients were submitted to surgery. Seventy-five percent were female. Median age and BMI were 26.5 years and 23.6 kg/m2, respectively. Median volume of fat grafted was 10 mL (interquartile range 8-12.25 mL). Results showed that the median preoperative volume measured by CT scan was larger than the photogrammetry measurement (12.48 mL vs 12.01 mL, respectively, P < .001). Likewise, a larger volume was measured by CT scan than by photogrammetry (15.54 mL vs 14.94 mL respectively, P < .001) 6 months postoperatively. However, there was no difference between CT scan and photogrammetry measurements of the change in volume from preoperatively to postoperatively (P = .89). There was no agreement between fat graft volume measurements obtained by 3D photogrammetry and CT scan techniques with regard to absolute values of fat graft volume measurements, however no difference was found between the 2 methods when comparing preoperative with postoperative fat graft volume variation.

DECT-CLUST: Dual-Energy CT Image Clustering and Application to Head and Neck Squamous Cell Carcinoma Segmentation.

Dual-energy computed tomography (DECT) is an advanced CT computed tomography scanning technique enabling material characterization not possible with conventional CT scans. It allows the reconstruction of energy decay curves at each 3D image voxel, representing varied image attenuation at different effective scanning energy levels. In this paper, we develop novel unsupervised learning techniques based on mixture models and functional data analysis models to the clustering of DECT images. We design functional mixture models that integrate spatial image context in mixture weights, with mixture component densities being constructed upon the DECT energy decay curves as functional observations. We develop dedicated expectation-maximization algorithms for the maximum likelihood estimation of the model parameters. To our knowledge, this is the first article to develop statistical functional data analysis and model-based clustering techniques to take advantage of the full spectral information provided by DECT. We evaluate the application of DECT to head and neck squamous cell carcinoma. Current image-based evaluation of these tumors in clinical practice is largely qualitative, based on a visual assessment of tumor anatomic extent and basic one- or two-dimensional tumor size measurements. We evaluate our methods on 91 head and neck cancer DECT scans and compare our unsupervised clustering results to tumor contours traced manually by radiologists, as well as to several baseline algorithms. Given the inter-rater variability even among experts at delineating head and neck tumors, and given the potential importance of tissue reactions surrounding the tumor itself, our proposed methodology has the potential to add value in downstream machine learning applications for clinical outcome prediction based on DECT data in head and neck cancer.

Fatigue damage evolution in asphalt mixture based on X-ray CT images

The fatigue damage of asphalt pavement occurs and develops under repeated vehicle loads, and its macro manifestation is the deterioration of mechanical properties and serviceability. In order to explore the internal cause of fatigue damage of asphalt mixtures, this paper proposed a method to obtain the internal section images of asphalt mixtures in different fatigue damage stages based on the X-ray CT (Computed Tomography) scanning technique and indirect tensile fatigue test. The fatigue damage evolutions in two different gradation types of AC and OGFC asphalt mixture were studied. The results show that the difference in gradation type causes different initial air void shapes, size and distribution, which result in different formation modes of the main cracks and fatigue damage resistance of asphalt mixture. The evolution of air voids during fatigue loading can be divided into three stages: compression, steady growth and rapid expansion. The macro fatigue damage presents an excellent linear relation (R-values > 0.98) with the internal structural damage.

A Multiphysics Understanding of Internal Short Circuit Mechanisms in Lithium-Ion Batteries upon Mechanical Stress Abuse

Lithium-ion batteries (LIBs) have played an increasingly dominant role in the current mobile society. Due to the risky safety testing procedure, ultra-rigorous demands of the testing facility, and complicated multiphysics nature of the safety issues, lack of high-fidelity models to describe the safety behaviors of lithium-ion batteries upon abusive loading has significantly deferred the further application of LIBs. Herein, firstly, mechanical behaviors of the battery component materials are characterized by both in-situ and post-mortem experiments. Then, we reveal the formation process of various internal short circuit (ISC) modes inside batteries upon different abusive loadings with the aid of ex-situ observation using the X-ray Computed Tomography scanning technique and post-mortem characterization of the battery samples. To quantify the stress-driven ISC mode and failure behavior of the component material, numerical models for all component materials are established and applied in a cell model which can reveal the deformation-material failure-material contact-different ISC mode formation process. To further quantify the relationship between electrothermal response and mechanical response of battery, we develop a 2D detailed model with fully coupling of electrochemo-thermal-mechanics governing laws consisting of a 2D mechanical model, 2D ISC model, 2D heat model and Thermal Runaway model. The multiphysics model demonstrates a promising generalization in various SOC and loading situations. Results highlight the power of computational modeling to understand the underlying mechanism of safety issues in energy storage systems in a broader context.

Evolution trend and weakening mechanism of mode-I fracture characteristics of granite under coupled thermo-hydro-mechanical and thermal treatments

Understanding the fracture behavior and fracture-morphology evolution of granite after coupled thermo-hydro-mechanical (THM) environment is important for many geotechnical projects. Previous studies mostly focused on the fracture-response mechanism of rocks after a thermal treatment, whereas only a few studies were conducted on the fracture toughness, fracture-process-zone (FPZ) size, and fracture-morphology evolution of granite after the THM multifield coupling. Therefore, a coupled THM damage treatment (i.e., THM-induced damage) of granite was carried out using a self-developed, high-temperature, and high-pressure multifield coupling triaxial universal tester. Subsequently, a series of test methods was employed, which included the full-field 3D digital-image correlation technique (real-time tracking of the strain/displacement field on the specimen surface), X-ray computed tomography scanning technique (to obtain the microdamage structure inside the specimen), and 3D laser scanner (to obtain the section morphology of the specimen). These methods were employed to study the response mechanism of mode-I fracture of a granite specimen (fracture toughness, fracture trajectory, FPZ size, and fractal dimension of the section topography). Furthermore, to elucidate the correlation between the coupled THM induced damage and fracture characteristics of granite, the same experimental test was also carried out on the granite using a thermal treatment. The result show that the evolution pattern of the fracture and morphological parameters of granite after the coupled THM treatment was different from that using only the thermal treatment, and the value of these physical parameters fluctuated at approximately 400 °C–500 °C. This is due to the limitation of the triaxial stress on the thermal expansion (25 °C–300 °C), competitive effect of “opening” and “closing” of micropores/microcracks (400 °C–500 °C), and deterioration of the coupled THM field (600 °C–650 °C). The results provide insights and theoretical guidance for high-temperature underground rock-mass engineering such as deep nuclear-waste reservoir.

Characterization of asphalt mixture using X-ray computed tomography scan technique after freeze-thaw cycle and microwave heating

• Recommend the optimum healing moment of different asphalt mixtures suffering from moisture damage. • HEL and SRL are introduced to compare the self-healing properties of different asphalt mixtures. • There are three moisture damage and microwave healing modes of asphalt mixtures on pores. • Valid pores and invalid pores are proposed to characterize the internal pores of asphalt mixtures. • The self-healing properties and characterization of different asphalt mixtures are compared. Microwave heating technology could heal micro-cracks caused by freeze-thaw (F-T) cyclic damage. The main objectives were to recommend the optimum heating moment and evaluate the difference between two typical mixtures during F-T cycle and microwave heating based on microstructure. To this end, cyclic F-T split tests and microwave heating tests were conducted to determine the best heating moment. In addition, the internal structure was scanned using X-ray computed tomography and evaluated using digital image processing. The results indicated that the optimum timing to heal two different asphalt mixtures (AC-13 and OGFC-13) occurred when the degrees of moisture damage were 39.8% and 42.4%, respectively. AC-13 exhibited better heating uniformity, and OGFC-13 exhibited better heating transferring. Moreover, F-T damage and microwave heating could change the internal structure: three types of moisture damage were seen in the voids: pore generation, connections, and expansion; pore number, porosity, pore area, and equivalent diameter first increased after the F-T cycles and then decreased after microwave heating, but the effect for OGFC-13 was more obvious; The F-T cycles mainly increased the number of valid pores, and microwave healing mainly increased the number of invalid pores; The damage and healing process of AC-13 and OGFC-13 mainly occurred on the 0.15–1.18 mm and 0.15–4.75 mm pores. This research could contribute to maintenance cost savings and revelation of F-T damage and microwave healing mechanism.

Comparison of stacking sequence on the low‐velocity impact failure mechanisms and energy dissipation characteristics of CFRP/Al hybrid laminates

AbstractCompared with the resin‐based composite laminates, fiber metal laminates (FMLs) have superior impact resistance. In this study, investigations were made to reveal the effects of stacking sequence on the low‐velocity failure mechanisms and energy dissipation characteristics of carbon fiber reinforced plastics (CFRP)/Al hybrid laminates with same areal density. Experiments were carried out to characterize the typical mechanical responses. Failure morphologies were evaluated by X‐ray computed tomography scanning techniques. Then numerical simulations based on three‐dimensional progressive damage analysis were applied to reveal the dynamic evolution process and energy dissipation characteristics. Results indicated that plastic deformation of aluminum layers acted as the dominant factor in energy dissipation. Stacking aluminum layers on the exterior surface could increase the absorbed impact energy and reduce the fracture behavior of the component layers. The specimens with more CFRP layers stacked on the surface exhibited more severe fracture behavior of component layers and larger delamination areas, thus promoting the energy dissipated by CFRP cracking and delamination. This work intended to provide practical guidance for the structural design of fiber reinforced polymer/metal hybrid protective structures.

Identification of water flow through non‐root soil macropores and along roots in shrub‐encroached grassland

AbstractIdentification of water flow through non‐root soil macropores and along roots using X‐ray computed tomography (CT) is still challenging because of limited methods to quantify roots and pore structures. This study selected shrub‐encroached grassland consisting of a mosaic of shrub patches and interspace grass patches and the original grassland as a control treatment. Twelve intact soil columns (0–30 cm deep) were excavated, which included four replicates each from the soils under the original grassland, the shrub patches and interspace grass patches. Three‐dimensional networks of soil macropores and roots were quantified using CT scanning and image analysis techniques, and active flow pathways were identified through KI tracing experiment using CT scanning. The results showed that the tracer depths of soils under the shrub patches and interspace grass patches were deeper than those of the original grassland, which was attributed to the well‐developed root system. The tracer volume density was significantly and positively correlated with soil macropore node density and root volume density (p &lt; 0.05), and significantly and negatively correlated with root mean angle (p &lt; 0.05). Soils under the shrub patches had lower tracer volume density than that under the interspace grass patches, which was attributed to the horizontal‐oriented roots under the shrub patches. The relative contribution of water flow along roots was larger than that through non‐root soil macropores 35 min after dye application. This provided direct evidence that shrub roots were the main pathway of macropore flow resulting in water flow into deep soil layers in the shrub‐encroached grassland.Highlights The tracer depths of shrub‐encroached grassland were deep due to well‐developed root system. Shrub patches had low tracer volume density due to the horizontal‐oriented roots. The contribution of water flow along roots was larger than that through non‐root soil macropores. Shrub roots were the main pathway of water flow.

Real‐world staging computed tomography scanning technique and important reporting discrepancies in pancreatic ductal adenocarcinoma

BackgroundComputed tomography (CT) is the first‐line staging imaging modality for pancreatic ductal adenocarcinoma (PDAC) which determines resectability and treatment pathways.MethodsBetween January 2016 and December 2019, prospectively collated data from two Australian cancer centres was extracted from the PURPLE Pancreatic Cancer registry. Real‐world staging CTs and corresponding reports were blindly reviewed by a sub‐specialist radiologist and compared to initial reports.ResultsOf 131 patients assessed, 117 (89.3%) presented with symptoms, 74 (56.5%) CTs included slices ≤3 mm thickness and CT pancreas protocol was applied in 69 (52.7%) patients. Initial reports lacked synoptic reporting in 131 (100%), tumour identification in 2 (1.6%) and tumour measurement in 13 (9.9%) cases. Tumour‐vascular relationship reporting was missing in 69–109 (52.7–83.2%) for regarding the key arterial and venous structures that is required to assess resectability. Initial reports had no comment on venous thrombus or venous collaterals in 80 (61.1%) and 109 (83.2%) and lacked locoregional lymphadenopathy interpretation in 13 (9.9%) cases. Complete initial staging report was present in 72 (55.0%) patients. Sub‐specialist radiological review resulted in down‐staging in 16 (22.2%) and up‐staging in 1 (1.4%) patient. Staging discrepancies were mainly regarding metastatic disease (12, 70.6%) and tumour‐vascular relationship (5, 29.4%).ConclusionReal‐world staging imaging in PDAC patients show low proportion of dedicated CT pancreas protocol, high proportion of incomplete staging reports and no synoptic reporting. The most common discrepancy between initial and sub‐specialist reporting was regarding metastases and tumour‐vascular relationship assessment resulting in sub‐specialist down‐staging in almost every fifth case.

Improving image quality by optimizing beam width and helical pitch in CT.

Expanding computed tomography (CT) detector coverage broadens the beam width, but inaccurate tube current application can reduce image quality at the boundaries between body regions with different attenuation values along the z-axis. This study aims to develop and validate a new CT scanning technique with a fixed pitch to achieve higher imaging quality. A cylindrical water phantom and an anthropomorphic chest phantom with different diameters represent a human body with different attenuation values. By optimizing the beam width and helical pitch, the pitch is fixed during scanning. The mean noise of the images and the standard deviation were calculated, and the coefficient of variation (COV) was compared to evaluate the uniformity of image noise according to the beam width. At the boundaries between regions with different attenuation values, the 10 mm beam width (COV: 0.065) in the water phantom showed a 47.7% COV reduction of image noise compared with the 20 mm beam width (COV: 0.125). In addition, the 20 mm beam width (COV: 0.146) in the chest phantom showed a 29.3% COV reduction of image noise compared with the 40 mm beam width (COV: 0.206). Thus, as the beam was narrowed, the mean noise was similar, but the standard deviation was reduced. The proposed CT scanning technique with a fixed pitch, optimized beam width, and helical pitch demonstrates that image quality can be improved without increasing radiation dose at the boundary between regions with different attenuation values.

Therapeutic effect of cycloserine combined with anti-tuberculosis drugs in the treatment of multidrug-resistant tuberculosis

&#x0D; &#x0D; &#x0D; &#x0D; Purpose: The present study analyzes the comprehensive therapeutic effect of cycloserine, in combination with anti-tuberculosis drugs using chest X-ray and chest CT (computed tomography) scan techniques.&#x0D; Methods: A total of 90 patients, diagnosed with multidrug resistant tuberculosis (MDR TB) were subjected to chest x-ray and CT scan before and after treatment in the two groups. Different views such as sagittal, coronal, lung window and multiplanar imaging of mediastinal window were taken. Some parameters such as case detection rate (CDR) in chest X-ray and CT scan and comprehensive curative effect were observed in two groups. Further, the changes in chest CT signs in addition to absorption of focus, cavity closure and changes in CT extra pulmonary signs were also observed.&#x0D; Results: The clinical profile of the patients and the course of disease were statistically insignificant (p &gt; 0.05). Total effectiveness rate and case detection rate (CDR) values exhibited a significant difference between the groups (p &lt; 0.05). Lung consolidation, nodules and cavities significantly improved in both groups before and after the treatment (p &lt; 0.05). Both groups showed significant improvements in extrapulmonary signs in CT scan (p &lt; 0.05) after the treatment.&#x0D; Conclusion: Based on the study outcomes, the CT scan method has good potentials for diagnosing and treating MDR TB at the early stages. Further, it can clarify the signs and outcomes of the disease at early stages, thus providing the medical fraternity a great opportunity to cure the disease.&#x0D; &#x0D; &#x0D; &#x0D;

A multiphysics understanding of internal short circuit mechanisms in lithium-ion batteries upon mechanical stress abuse

Lithium-ion batteries (LIBs) have played an increasingly dominant role in the current mobile society. Due to the risky safety testing procedure, ultra-rigorous demands of the testing facility, and complicated multiphysics nature of the safety issues, the lack of high-fidelity models to describe the safety behaviors of lithium-ion batteries upon abusive loading has significantly deferred the further application of LIBs. Herein, by assistance from the ex-situ observation using the X-ray Computed Tomography scanning technique and postmortem characterization of the battery samples, we reveal the formation process of various internal short circuit (ISC) modes upon abusive loading guiding our modeling. Strain-based and ISC mode-dependent criteria are first developed to establish the mechanical-electrical coupling relationship. Particularly, we establish a fully multiphysics-coupled model capable of identifying various ISC modes and describing the entire evolution process of the battery from the initial deformation to the final thermal runaway (TR) of the LIBs. The multiphysics model demonstrates a promising generalization in various SOC and loading situations. Finally, the multiphysics model is applied for 100% SOC of the LIB to reveal the evolution mechanism of deformation-different ISC modes-TR. Results highlight the power of computational modeling to understand the underlying mechanism of safety issues in energy storage systems in a broader context.

Numerical assessment of natural respiration and particles deposition in the computed tomography scan airway with a glomus tumour

The human respiratory tract has a complex airflow pattern. If any obstruction is present in the airways, it will change the airflow pattern and deposit particles inside the airways. This is the concern of breath quality (inspired air), and it is decreasing due to the unplanned production of material goods. This is a primary cause of respiratory illness (asthma, cancer, etc.). Therefore, it is important to identify the flow characteristics in the human airways and airways with a glomus tumour with particle deposition. A numerical diagnosis is presented with an asymmetric unsteady-state light breathing condition (10 l/min). An in vitro human respiratory tract model has been reconstructed using computed tomography scan techniques and an artificial glomus tumour developed 2 cm above a carina on the posterior wall of the trachea. The transient flow characteristics are numerically simulated with a realizable (low Reynolds number) k–ɛ turbulence model. The flow disturbance is captured around the tumour, which influenced the upstream and downstream of the flow. The flow velocity pattern, wall shear stress and probable area of inflammation (hotspot) due to suspended particle deposition are determined, which may assist doctors more effectively in aerosol therapy and prosthetics of human airways illness.

Three dimensional modelling of aluminum foam through computed tomography scan technique

PurposeThis study aims to generate different three-dimensional (3D) foam models using computer tomography (CT) scan and solid continuum techniques. The generated foam models were used to study deformation mechanism and the elastic-plastic behaviour with the existing experimental foam behaviour.Design/methodology/approachCT scan model was generated by combing 2D images of foam in MIMICS software. Afterwards, it was imported in ABAQUS/CAE software. However, solid continuum model was generated in ABAQUS/CAE software by using crushable foam properties. Then, the generated foam models were sets boundary conditions for a compression test.FindingsCT scans capture the actual morphology of foam sample which may directly an image based finite element foam model. The sectional views of both the models were used to observe deformation mechanism on compression. The real compressive behaviour of foam was visualised in CT-Scan foam model. It was observed that CT-scan model was the more accurate modelling method than crushable foam model.Originality/valueThe internal structure of foam is very complex and difficult to analyse. Therefore, CT-scanning may be the accurate method for capturing the macro-level detailing of foam structure. A CT-scan foam model can be used for multiple times for mechanical analysis using a simulation software, which may reduce the manufacturing and the experimental cost and time.

Improving practice in radiology: a quality-improvement project examining CT colonography patient dose and scanning technique

To audit scanning technique and patient doses for computed tomography (CT) colonography (CTC) examinations in a large UK region and to identify opportunities for quality improvement. Scanning technique and patient dose data were gathered for both contrast-enhanced and unenhanced CTC examinations from 33 imaging protocols across 27 scanners. Measurements of patient weight and effective diameter were also obtained. Imaging protocols were compared to identify technique differences between similar scanners. Scanner average doses were calculated and combined to generate regional diagnostic reference limits (DRLs) for both examinations. The regional DRLs for contrast-enhanced examinations were volume CT dose index (CTDIvol) of 11 and 5 mGy for the two scan phases (contrast-enhanced and either delayed phase or non-contrast enhanced respectively), and dose-length product (DLP) of 740 mGy·cm. For unenhanced examinations, these were 5 mGy and 450 mGy·cm. These are notably lower than the national DRLs of 11 mGy and 950 mGy·cm. Substantial differences in scan technique and doses on similar scanners were identified as areas for quality-improvement action. A regional CTC dose audit has demonstrated compliance with national DRLs but marked variation in practice between sites for the dose delivered to patients, notably when scanners of the same type were compared for the same indication. This study demonstrates that the national DRL is too high for current scanner technology and should be revised.

Model-based experimental analysis of enhanced boiling heat transfer by micro-nano porous surfaces

Small bubbles are desirable to be frequently generated and detach from the heated surface in pool boiling. Bubble nucleation and bubble departure can be influenced by the size of micro-nano structure. In this work, four honeycomb micro-nano porous copper surfaces with successively increasing pore sizes are prepared by controlling the electrodeposition current densities. Both experiments on saturated pool boiling of water and numerical simulations are conducted. The heat transfer performance of prepared surfaces is improved significantly and then decreased slightly when the pore size ranges from 48 μm to 128 μm, with maximum critical heat flux and heat transfer coefficient reaching 187.3 W/cm2 and 23.7 W/cm2/K, respectively. Numerical simulations considering three-dimensional (3D) complex geometries of the four samples reconstructed by a computed tomography scanning technique are conducted. Numerical results show that the percentage of heat flowing out of the three-phase contact lines by phase change at high heat-flux supply can increase to 90%, which is consistent with previous literature results. Subject to a parametric 3D transient heat-conduction forward model developed in this work, a multi-layer end-to-end convolutional neural network is for the first time constructed and trained to solve the corresponding ill-posed inverse problems of 3D transient heat conduction efficiently. It provides a promising alternative way to develop a highly efficient temperature-to-heat-flux soft sensor technique for both boiling applications and many other similar engineering problems.

Computed Tomographic and Morphometric Study of Cervical Vertebrae in Healthy White New Zealand Rabbit (Oryctolagus Cuniculus)

BACKGROUND: Nowadays, use of rabbits in research as laboratory animals is quite prevalent, however imaging modal-ities for producing anatomical illustrations are rare. Computed tomography (CT) is a nonaggressive modality which provides more anatomical detailed data. OBJECTIVES: This study aimed to create a plenary and exact deliniation and morphometric evaluation of cervical ver-tebrae in rabbits. METHODS: A CT scanner with two detectors was used in this study. Several parameters were measured in 10 healthy, adult female white New Zealand rabbits and the results were evaluated. RESULTS: Some parameters including VBH, SCH, PDL, PDW, VBL, EPH, and EPW had no significant difference through cervical vertebrae but other parameters such as SPH, TPL, TPW, SPA, and TPA were significantly different. In the fifth cervical vertebrae, transverse process had three parts, as well as having a big transverse foramen while in the sixth vertebra, transverse process resembled a wide plate CONCLUSIONS: VBH had an invariable measure from the second to seventh cervical vertebrae. SPH had an invariable measure from the second cervical vertebra to the sixth one, then once more it increased at the location of the seventh cervical vertebra and was invariable up to the first thoracic vertebra. This study presents a complete and precise description and morphometric evaluation of cervical vertebrae in rabbits using CT scan. As an important feature of this study, no specimen was killed and anatomical studies were performed using the CT scan technique .

Evaluation of exposure dose in fetal computed tomography using organ-effective modulation

Organ-effective modulation (OEM) is a computed tomography scanning technique that reduces the exposure dose to organs at risk. Ultrasonography is commonly used for prenatal imaging, but its reliability is reported to be limited. Radiography and computed tomography (CT) are reliable but pose risk of radiation exposure to the pregnant woman and her fetus. Although there are many reports on the exposure dose associated with fetal CT scans, no reports exist on OEM use in fetal CT scans. We measured the basic characteristics of organ-effective modulation (X-ray output modulation angle, maximum X-ray output modulation rate, total X-ray output modulation rate, and noise modulation) and used them in a Monte Carlo simulation to evaluate the effect of this technique on fetal CT scans in terms of image quality and exposure dose to the pregnant woman and fetus. Using ImPACT MC software, Monte Carlo simulations of OEMON and OEMOFF were run on 8 cases involving fetal CT scans. We confirmed that the organ-effective modulation X-ray output modulation angle was 160°; the X-ray output modulation rate increased with increasing tube current; and no modulation occurred at tube currents of 80 mA or below. Our findings suggest that OEM has only a minimal effect in reducing organ exposure in pregnant women; therefore, it should be used on the anterior side (OEMON,front) to reduce the exposure dose to the fetus.