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Comparison of pharyngeal airway volume in different skeletal facial patterns using cone beam computed tomography
摘要： Background: This study aimed to compare the pharyngeal airway volume in class I,II and III skeletal malocclusion patients using cone beam computed tomography (CBCT). Material and Methods: This retrospective, cross sectional study was conducted on lateral cephalograms of 71 patients derived from their CBCT scans. Using the ANB angle, the patients were divided into class I,II and III malocclusion. Two observers used Dolphin 3D software to calculate the pharyngeal airway volume, airway area, minimum axial area, minimum area location, airway length and morphology. Data were analyzed using one-way ANOVA, Kruskal-Wallis test, Tukey’s test, Spearman’s correlation coefficient and multiple regression analysis. Results: The three skeletal classes were significantly different in airway volume, minimum axial area, mean airway area and airway morphology (P<0.05). Significant differences were found in airway volume and mean airway area between class II and III patients (P<0.05). The minimum axial area and airway morphology in class III patients were greater than those in class I and II patients (P<0.05). Every one unit increase in the ANB angle decreased the airway volume by 0.261 units. The effect of ANB angle on airway volume was statistically significant and it was shown that one unit increase in the angle decreased the airway volume by 453.509 units. Conclusions: A significant correlation exists between the skeletal facial pattern and upper airway dimensions. In our study, the total airway volume and the mean airway area of class III patients were larger than those in class II patients.
关键词： Cone-Beam computed tomography,malocclusion,pharyngeal airway volume
更新于2025-09-10 09:29:36
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Diagnostic value of single-source dual-energy spectral computed tomography in differentiating parotid gland tumors: initial results
摘要： Background: An accurate preoperative diagnosis that helps distinguish between benign and malignant parotid gland tumors is very important because the results strongly affect surgical procedures. We aimed to evaluate the value of single-source dual-energy computed tomography (ssDECT) in differentiating malignant from benign parotid gland tumors. Methods: Fifty patients underwent enhanced neck ssDECT scanning before surgery. The images were analyzed using the gemstone spectral imaging (GSI) viewer software. Results: Fifty-two tumors (43 patients) were con?rmed histopathologically, comprising of 12 pleomorphic adenomas (PAs), 24 Warthin tumors (WTs) (15 patients), and 16 malignant tumors (MTs). The iodine concentration (IC), normalized iodine concentration to common carotid artery (NICA) and slope value of the spectral curve (λHU) of the WTs were signi?cantly higher than those of MTs and PAs (all P<0.05). The optimal IC, NICA and λHU thresholds for differentiating PAs from MTs were 0.91 mg/mL, 0.15 and 1.09, respectively, achieving sensitivities of 91.7%, 91.7% and 91.7%, speci?cities of 95.0%, 85.0% and 95.0%, and accuracies of 94.2%, 86.5% and 94.2%, respectively for distinguishing PAs from MTs. The optimal IC, NICA and λHU thresholds for distinguishing WTs from MTs were 1.46 mg/mL, 0.20 and 1.72, achieving sensitivities of 91.7%, 95.8% and 91.7%, and speci?cities of 89.3%, 85.7% and 89.3%, respectively. The accuracy was 90.4%, 90.4% and 90.4%, respectively. Conclusions: The parameters of ssDECT in enhanced CT scans are useful in the differential diagnosis of parotid tumors.
关键词： parotid gland tumors,Computed tomography (CT),dual-energy
更新于2025-09-10 09:29:36
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The feasibility of low-dose CT perfusion imaging in gastric cancer
摘要： PURPOSE: To investigate feasibility of applying low-dose CT perfusion imaging (CTPI) to diagnose gastric cancer. MATERIALS AND METHODS: Twenty patients with gastric cancer con?rmed by endoscopic biopsy were undergone routine dose (120 kV, 100 mA) and low-dose (120 kV, 50 mA) CTPI examination, respectively. The original data were processed by body perfusion software, and the perfusion parameters values including blood ?ow (BF), blood volume (BV) and permeability surface (PS) of gastric cancer were measured. Statistical data analyses including paired-samples t test, Pearson correlation analysis and Bland-Altman consistency test were used to compare the perfusion parameters values between the routine dose and low-dose CTPI examinations. Radiation dosage, which the patients received during two CTPI examinations, was also calculated and compared. RESULTS: There were no statistical differences in the BF, BV and PS values between routine dose group and low-dose group (P > 0.05), and there were signi?cant correlation in the BF, BV and PS values between two groups (P < 0.01). The consistency of BF and BV values between the two groups was preferable to that of PS value. The radiation dosage of the low-dose group was much less than that of routine dose group, and the CTDIvol and DLP values of low-dose CTPI were decreased by 50%, respectively. CONCLUSION: The parameters BF and BV values may play a valuable role in the diagnosis and assessment of gastric cancer in low-dose CTPI examination.
关键词： gastric cancer,computed tomography,Low-dose,perfusion imaging
更新于2025-09-10 09:29:36
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Nitroxide-radicals–modified gold nanorods for in vivo CT/MRI-guided photothermal cancer therapy
摘要： This article presents a report of the synthesis, characterization, and biomedical application of nitroxide-radicals–modified gold nanorods (Au-TEMPO NRs) for imaging-guided photothermal cancer therapy. Patients and methods: Au nanorods were synthesized through seed-mediated growth method, 4-Amino-TEMPO was added and the reaction proceeded under magnetic stirring. Results: With a mean length of 39.2 nm and an average aspect ratio of approximately 3.85, Au-TEMPO NRs showed good photothermal ability when they were irradiated by 808-nm laser. Au-TEMPO NRs could be stored in PBS for more than 1 month, showed no cytotoxicity against both tumor and normal cells at a concentration of up to 3 mg/mL, and functioned as a dual-mode contrast agent for CT/magnetic resonance (MR) imaging in vitro and in vivo, due to their high X-ray attenuation of Au and good r1 relaxivity of nitroxide radicals. Further, they had a long retention time (~4 hours) in the main organs, which enabled a long CT/MR imaging time window for diagnosis. Bio-distribution results revealed that these Au-TEMPO NRs passively aggregated in the liver and spleen. After irradiation by 808-nm laser, Au-TEMPO NRs could ablate the solid tumor in 4T1 tumor-bearing mice, which implied they were a potential theranostic agent for dual-mode imaging and photothermal cancer therapy. Conclusion: This type of Au-TEMPO NRs with the abilities of CT/MR imaging and photothermal therapy, can play an active role in imaging-guided photothermal cancer therapy.
关键词： TEMPO,magnetic resonance imaging,PTT,Au NRs,computed tomography
更新于2025-09-10 09:29:36
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Comparison of Image Qualities of 80 kVp and 120 kVp CT Venography Using Model-Based Iterative Reconstruction at Same Radiation Dose
摘要： Purpose: To compare image qualities of 80 kVp CT venography (CTV) and 120 kVp CTV by model-based iterative reconstruction (MBIR) at the same radiation dose. Materials and Methods: Sixty-nine patients that underwent CTV using 80 kVp (36 patients, group 1) or 120 kVp (33 patients, group 2) with MBIR at the same radiation dose were enrolled, and objective and subjective image qualities were assessed independently by two radiologists. Results: Mean vascular enhancement and contrast-to-noise ratio were significantly higher in group 1 than in group 2 for inferior vena cavas, femoral veins, and popliteal veins (p < 0.001), and there was significantly lower objective image noise in group 1 (p < 0.001). Subjective analysis revealed image quality was significantly higher in group 1 and image noise was significantly higher in group 2 (p < 0.001). Mean dose-length products was not significantly lower in group 1 (356.1 ± 153.7 mGy cm) than in group 2 (370.1 ± 77.1 mGy cm) (p = 0.635). Conclusion: CTV at 80 kVp with MBIR is a better protocol than CTV at 120 kVp with MBIR at the same radiation dose.
关键词： Radiation Dosage,Multidetector Computed Tomography,Veins,Lower Extremity
更新于2025-09-10 09:29:36
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Stray light in cone beam optical computed tomography: III. Evaluation of a redesigned large-volume commercial scanner based on a convergent light source
摘要： Optical cone beam computed tomography (CT), using a digital camera to acquire 2D projection images, provides a fast, mechanically simple method for 3D radiation dosimetry. However, original cone beam designs had poor accuracy as a result of considerable scatter/stray light reaching the camera. Previously, our group presented a redesigned convergent light source for optical cone beam CT that considerably reduced stray light contribution and improved accuracy (Dekker et al 2016 Phys. Med. Biol. 61 2910). Here, we performed an evaluation of a newly updated commercial optical cone beam CT scanner (VistaTM, ModusQA, London, Canada) based on that design. Two different light source configurations were examined: the manufacturer’s default configuration which uses a 10 cm wide, 5 cm high diffuser light source, and a smaller, 1.5 cm diameter diffuser light source that more closely aligns with our previously described design. We imaged large volume (15 cm diameter cylinders) absorbing and scattering solution phantoms as well as a 1.25 cm diameter absorber placed within 15 cm diameter gel-like scattering phantom. Optical CT reconstructions were compared against narrow-beam measurements of attenuation made by placing an aperture in the optical CT system. Our results show that considerable stray light is present when using the manufacturer’s default configuration, as cupping artifacts and large (?10%) discrepancies between optical CT and narrow-beam attenuation measurements occur when imaging scattering phantoms. However, when imaging is performed using the 1.5 cm diameter source, optical CT measurements agree with narrow-beam measurements within ～3% for both absorbing and scattering objects, as well as the small absorber in a scattering medium. Using this light source will require higher optical quality vessels than are currently provided by the manufacturer.
关键词： optical computed tomography,stray light,3D dosimetry,cone beam
更新于2025-09-10 09:29:36
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Evaluation of the Internal Structure of the Multilayer Ceramic Mould for Precision Casting Critical Parts of Aircraft Engines by X-ray Computed Tomography
摘要： The aim of the study was to present the possibilities of X-ray computed tomography to evaluate the internal discontinuities in multilayer ceramic moulds for precision casting critical parts of aircraft engines. Study for determination of internal discontinuities such as: porosity, micro-cracks and delamination at the ceramic moulds was carried out using the method of X-ray computed tomography. Using this method allowed to obtain a 3D virtual model of the ceramic form and, consequently, the measurement of porosity and thickness both the first layer and the constructional layer in the multilayer ceramic mould. The results are presented possibilities of computer tomography as a tool for microanalysis 3D, identify internal discontinuities and measurement of geometrical size for assessing the quality of ceramic mold in relation to the research of its technological structure.
关键词： Precision casting,Ceramic shell moulds,X-ray computed tomography
更新于2025-09-10 09:29:36
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Cone-beam computed tomography guidance with navigational overlay for percutaneous lung nodule biopsy
摘要： Background Cone-beam CT is increasingly used in pediatric interventional radiology procedures. However, the feasibility or safety of using this mode of imaging guidance for percutaneous lung nodule biopsy in children has not been assessed. Objective To retrospectively evaluate safety and diagnostic accuracy of percutaneous lung nodule biopsy in people treated at a pediatric hospital using cone-beam CT with navigational overlay. Materials and methods Thirty-six consecutive patients from two large tertiary-care children’s hospitals with lung nodules of 48 mm or smaller underwent percutaneous lung nodule biopsy using cone-beam CT with navigational overlay. We evaluated patient demographics, pre- and post-biopsy diagnoses, number of biopsy passes, complications, radiation exposure and technical success. Results Percutaneous lung nodule biopsy was performed for 37 nodules in 36 patients (23 males, 13 females, median age 15.5 years, range 8 months to 23 years). One patient underwent biopsy of two nodules at a single procedure. Median patient weight was 55 kg (range 8–97 kg). Pre-biopsy diagnoses included metastatic sarcoma or other solid tumor (n=11), leukemia/lymphoma (n=13), infection (n=10), chronic granulomatous disease (n=2) and post-transplant lymphoproliferative disorder (PTLD; n=1). Mean number of passes was 5 (range 2–15). Mean pre-procedure international normalized ratio (INR) was 1.1 and platelet count 193 × 109/L. Diagnostic specimens were obtained in 32 of 36 patients (89%). Thirteen complications were encountered in 12 patients (33% of cohort), including 9 pneumothoraces (4 requiring chest tubes); 1 hemothorax, which required a chest tube; and 3 self-limited pulmonary hemorrhages. Mean and median radiation doses were as follows: fluoroscopy time 3 min and 2.4 min, dose-area product (DAP) (recorded in 31 patients) 23,402 Gy·cm2 and 12,453 Gy·cm2, and air kerma 88 mGy and 58 mGy. Conclusion Percutaneous lung nodule needle biopsy can be performed accurately using cone-beam CT with navigational overlay.
关键词： Children,Biopsy,Lung nodule,Navigational overlay,Cone-beam computed tomography
更新于2025-09-10 09:29:36
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A method for obtaining three-dimensional measurements of HDR brachytherapy dose distributions using Fricke gel dosimeters and optical computed tomography
摘要： This study aimed to develop a method for performing accurate, high-resolution, three-dimensional (3D) Fricke gel dosimetry measurements of high dose rate (HDR) brachytherapy dose distributions using optical computed tomography (CT). A multi-needle brachytherapy gel phantom was purpose-built to contain four stainless-steel brachytherapy needles and a sample of Fricke Xylenol gel. A Paris-style HDR brachytherapy treatment was planned and delivered to the gel, which was then read out using a novel optical CT scanning method; all the brachytherapy needles were removed prior to scanning and replaced with a refractive index matched fluid. The removal of the stainless-steel needles during pre- and post-irradiation scanning minimised the potential for artefacts caused by missing ray-sum data. Results showed good agreement between measured and calculated doses (within 1%) at all positions greater than 0.1 cm from each needle. This study demonstrated that 3D Fricke gel phantoms may be valuable tools in verifying HDR brachytherapy treatments. The phantom construction and optical CT scanning method proposed in this work has the potential to enable routine quality assurance measurements of complex HDR brachytherapy treatment deliveries via accurate and detailed three-dimensional dose measurements.
关键词： Optical computed tomography,Fricke gel,Brachytherapy
更新于2025-09-10 09:29:36
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Characteristics of CCD Based Optical CT Scanner for Therapeutic Radiation Dosimetry
摘要： A CCD camera and an LED light source were combined to fabricate a compact optical CT scanner for the therapeutic radiation dose evaluation of a polymer gel dosimeter. After the collimated beam emitted by the LED passed through aquarium, gel phantom, and telecentric lens, an image was collected by the CCD camera and reconstructed using MATLAB. By using a stepping motor and LabVIEW, the gel dosimeter was rotated at every 0.72o, and the time for collecting 500 slice images per a revolution was within 20 min. At a spatial frequency of 4.5 lp/mm of the optical CT scanner, the modulation transfer function value was 72%. The linear correlation coefficient of the optical CT scanner for the polymer gel dosimeter was 0.987.
关键词： Optical Computed Tomography Scanner,Polymer Gel,Dosimetry
更新于2025-09-10 09:29:36