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@#Cone beam computed tomography (CBCT) has been widely used in various fields of dentistry. The diagnosis of root fractures, especially vertical root fractures (VRFs) with CBCT images, has been a research hotspot since then. Research on this area mainly includes the following five aspects: ① the diagnostic efficiency of CBCT images for root fractures; ② the influence of scanning parameters on the diagnostic accuracy of CBCT images in root fractures, such as scanning field of view, spatial resolution, tube current and tube voltage; ③ whether the application of image postprocessing techniques, especially metal artifact reduction (MAR), can improve the diagnostic accuracy of root fractures after root canal treatment and/or there is a post core in the root canal; ④ establishment and validation of clinical diagnosis model for vertical root fracture; and ⑤ application of artificial intelligence technology and contrast agent in root canals for the diagnosis of CBCT image in root fractures. Compared with periapical radiographs, CBCT images can improve the diagnostic accuracy of root fractures in nonendodontic treated teeth; however, for teeth that have undergone endodontic treatment, the diagnosis of VRF must be combined with clinical signs. Vertical bone resorption in the buccolingual (palatal) direction is a characteristic indicator of VRF. The width of the VRF is an important factor affecting the diagnostic accuracy, but the voxel size used in CBCT scanning is not a necessary factor affecting its diagnostic accuracy; the fracture direction does not affect the diagnostic accuracy of the VRF. Image postprocessing techniques, especially MAR, cannot improve the diagnostic accuracy of VRF and may also reduce the diagnostic efficiency, so they are not recommended for clinical application.
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Objective To investigate the influence of PET/CT imaging conditions (acquisition time, bed overlap, reconstruction matrix, iteration times, filter kernel size, and attenuation correction) on the spatial resolution of images. Methods Two PET/CT devices, GE Discovery Elite and GE Discovery ST-16, were used to scan the elliptical column resolution model in one and two beds (list mode, acquisition time of 6 min). Images were reconstructed under the commonly used clinical reconstruction conditions (Elite: VPFX-S algorithm, ST-16: VUE Point HD algorithm) at 1-6 min/bed, different iteration times of 2-10 times, different filter kernel sizes of 2.0-10.0 mm (Elite), and different reconstruction matrices, with attenuation correction or not. The spatial resolution of reconstructed PET images was represented by the full width at half maximum (FWHM) of the line spread function. Results Under the clinical acquisition conditions, when the acquisition time was 1 min, 2 min, 3 min, 4 min, 5 min, and 6 min, the FWHMElite of spatial resolution at the center of field of view was (4.06 ± 0.08) mm, (4.05 ± 0.20) mm, (4.01 ± 0.01) mm, (4.05 ± 0.07) mm, (4.05 ± 0.03) mm, and (4.08 ± 0.06) mm, and the FWHMST-16 was (5.76 ± 0.12) mm, (5.72 ± 0.11) mm, (5.74 ± 0.09) mm, (5.78 ± 0.05) mm, (5.75 ± 0.09) mm, and (5.77 ± 0.07) mm. When the phantom was located in the center of one bed and the overlap of two beds, the line FWHMElite at the center was (4.04 ± 0.01) mm and (4.04 ± 0.01) mm, and the FWHMST-16 was (5.39 ± 0.19) mm and (5.38 ± 0.07) mm, respectively. The FWHMElite at the center was (4.07 ± 0.18) mm, (4.25 ± 0.10) mm, and (4.73 ± 0.08) mm at the matrices of 256 × 256, 192 × 192, and 128 × 128, respectively. The FWHMElite at the center was (4.65 ± 0.43) mm, (4.77 ± 0.27) mm, (4.02 ± 0.01) mm, (4.11 ± 0.04) mm, and (9.94 ± 0.01) mm at the filter kernel sizes of 2.0 mm-10.0 mm (interval of 2.0 mm), respectively. The FWHMElite at the center was (4.17 ± 0.27) mm, (4.27 ± 0.21) mm, (4.11 ± 0.05) mm, (4.18 ± 0.04) mm, and (4.12 ± 0.06) mm at 2-10 iterations (interval of 2 times), respectively. The FWHMElite at the center was (4.14 ± 0.01) mm and (4.18 ± 0.08) mm with and without attenuation correction, respectively. At the same acquisition time and bed, the spatial resolution of Elite images was improved by about 40.57% compared with that of ST-16 images. Conclusion The spatial resolution of images obtained at the matrix of 256 × 256 is higher than that of images obtained at the matrices of 192 × 192 and 128 × 128 in the same model. Elite images have the best spatial resolution at the reconstruction filter kernel size of 6.0 mm. Under the same imaging conditions, Elite images show significantly better spatial resolution compared with ST-16 images. Acquisition time, overlap of beds, iteration times, and attenuation correction have no significant effect on the spatial resolution of PET images.
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Development of a novel in vivo lung perfusion(IVLP)procedure allows localized delivery of high-dose doxorubicin(DOX)for targeting residual micrometastatic disease in the lungs.However,DOX delivery via IVLP requires careful monitoring of drug level to ensure tissue concentrations of this agent remain in the therapeutic window.A small dimension nitinol wire coated with a sorbent of biocompatible morphology(Bio-SPME)has been clinically evaluated for in vivo lung tissue extraction and determina-tion of DOX and its key metabolites.The in vivo Bio-SPME-IVLP experiments were performed on pig model over various(150 and 225 mg/m2)drug doses,and during human clinical trial.Two patients with metastatic osteosarcoma were treated with a single 5 and 7 μg/mL(respectively)dose of DOX during a 3-h IVLP.In both pig and human cases,DOX tissue levels presented similar trends during IVLP.Human lung tissue concentrations of drug ranged between 15 and 293 μg/g over the course of the IVLP procedure.In addition to DOX levels,Bio-SPME followed by liquid chromatography-mass spectrometry analysis generated 64 metabolic features during endogenous metabolite screening,providing information about lung status during drug administration.Real-time monitoring of DOX levels in the lungs can be per-formed effectively throughout the IVLP procedure by in vivo Bio-SPME chemical biopsy approach.Bio-SPME also extracted various endogenous molecules,thus providing a real-time snapshot of the physi-ology of the cells,which might assist in the tailoring of personalized treatment strategy.
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Objective To evaluate and compare the radiation dose and image quality of the new generation of whole body mobile CT (BodyTom CT) with commonly used fixed CT.Methods The image quality was evaluated with CATPHAN 500 performance test body model.The radiation dose was measured by conventional 100 mm pen ionization chamber and PMMA body phantom and head phantom (head diameter 160 mm,phantom diameter 320 rm and width 140 mm).Results The spatial and contrast resolution of BodyTom CT images were similar to two kinds of fixed CT(P ＞ 0.05).The CNR of image with BodyTom CT decreased by about 20％:In head scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-4.82,-6.98,P ＜ 0.05;with standard,t =-20.60,-20.09,P ＜0.05);in body scan mode,significantly lower than that with Philps 64 slice CT and Toshiba 320 slice CT (with soft,t =-5.67,-12.82,P ＜ 0.05;with standard,t =-3.39,-9.18,P ＜ 0.05;with sharp,t =-3.88,-3.21,P ＜0.05).The radiation dose with BodyTom CT was significantly higher than that with fixed CT:in body model,22.97％ than that with Philps 64(t=9.48,P＜0.05),29.6％ than that with Toshiba 320 slice CT(t =11.66,P ＜0.05);in head model,29.76％ than that with Philps 64 slice CT(t=23.44,P＜0.05),33.22％ than that with Toshiba 320 slice CT(t=23.11,P＜0.05).Conclusions The radiation dose with mobile CT was over 20％ higher than that with routine multi-row CT while with the similar image quality.
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Objective To explore the influence of changing probe crystal thickness on the performance of single photon emission computed tomography (SPECT),so as to achieve quantitative improvements and in-depth analyses of the related reasons and to provide effective measures in improving the image quality of SPECTs.Methods Both 12 SPECT units each of 1 inch (1 inch =2.54 cm) thick crystal and 35 SPECT units each of 3/8 inch thick crystal were chosen.Both intrinsic uniformity and intrinsic spatial resolution were measured according to the National Electrical Manufacturers Association (NEMA) standard.The performance was compared between SPECT units with 1 inch thick probe and 3/8 inch thick crystal.Results The intrinsic uniformity measured for 1 inch thick probe and 3/8 inch thick crystal were (3.22 ± 0.83)％ and (2.51 ± 0.65)％.The difference between the two groups was statistically significant (t =-3.601,P ＜ 0.05).Intrinsic spatial resolutions of 1 inch thick probe and 3/8 inch thick crystal were (4.60± 0.14) and (3.70 ± 0.35) mm,with statistical significance between the two groups (t =-13.03,P ＜ 0.05).Conclusions The crystal thickness is a significant factor influencing SPECT's intrinsic uniformity and intrinsic spatial resolution.It is recommended that effective measures be taken to compensate the declined image quality due to crystal thickness change,to make sure the equipment is qualified for clinical use.
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Objective To test the spatial resolution and average glandular dose (AGD) of full field digital mammography system to obtain high-resolution and contrast breast X-ray images with the lowest dose.Methods The M12 breast X-ray performance test phantom was placed on the breast support center position,then line-pair card was put on the M12 phantom and fixed groove,and exposure was carried out with auto exposure control,28 kV tube voltage and common anode filtration combination so as to detect the spatial resolution.Half-value layer (HVL) was measured by Fluke TNT12000 ray detection tools,2 mm-thickness plate and aluminum sheets with different thicknesses,and then AGD was calculated accordingly.Results The spatial resolutions were all higher than 7 lp/mm and proved to meet the quality standard,which had the vertical spatial resolution being 8 lp/mm,the maximum value of the lateral spatial resolution being 10 lp/mm and the minimum value being 8 lp/mm.AGD was lower than 2 mGy and then proved qualified which was limited within 0.60 and 0.61 mGy.Conclusion The test of spatial resolution and AGD of full digital mammography system can assess the performance and radiation dose,reflect the performance of equipment,ensure image quality and lower radiation dose.
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Objective To test the spatial resolution and average glandular dose (AGD) of full field digital mammography system to obtain high-resolution and contrast breast X-ray images with the lowest dose.Methods The M12 breast X-ray performance test phantom was placed on the breast support center position,then line-pair card was put on the M12 phantom and fixed groove,and exposure was carried out with auto exposure control,28 kV tube voltage and common anode filtration combination so as to detect the spatial resolution.Half-value layer (HVL) was measured by Fluke TNT12000 ray detection tools,2 mm-thickness plate and aluminum sheets with different thicknesses,and then AGD was calculated accordingly.Results The spatial resolutions were all higher than 7 lp/mm and proved to meet the quality standard,which had the vertical spatial resolution being 8 lp/mm,the maximum value of the lateral spatial resolution being 10 lp/mm and the minimum value being 8 lp/mm.AGD was lower than 2 mGy and then proved qualified which was limited within 0.60 and 0.61 mGy.Conclusion The test of spatial resolution and AGD of full digital mammography system can assess the performance and radiation dose,reflect the performance of equipment,ensure image quality and lower radiation dose.
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Objective To design a test phantom for clinical routine quality control of magnetic resonance imaging (MRI).Methods The commonly used phantom such as Magphan SMR170 and Victoreen 76-903 were used for experiments with the same parameters,and the test data of all the modules were compared.The advantages and disadvantages of all the modules were analyzed,and an optimization scheme was proposed accordingly.Results The phantom could be applied to the detection of high-image-quality MRI machine,and solved the problems in positioning,size matching and etc.Conclusion The new phantom meets the demand of magnetic resonance imaging clinical routine testing,and provides a certain reference for phantom optimization design.
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OBJECTIVE: To evaluate the impact of iterative reconstruction (IR) on the assessment of diffuse interstitial lung disease (DILD) using CT. MATERIALS AND METHODS: An American College of Radiology (ACR) phantom (module 4 to assess spatial resolution) was scanned with 10–100 effective mAs at 120 kVp. The images were reconstructed using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), with blending ratios of 0%, 30%, 70% and 100%, and model-based iterative reconstruction (MBIR), and their spatial resolution was objectively assessed by the line pair structure method. The patient study was based on retrospective interpretation of prospectively acquired data, and it was approved by the institutional review board. Chest CT scans of 23 patients (mean age 64 years) were performed at 120 kVp using 1) standard dose protocol applying 142–275 mA with dose modulation (high-resolution computed tomography [HRCT]) and 2) low-dose protocol applying 20 mA (low dose CT, LDCT). HRCT images were reconstructed with FBP, and LDCT images were reconstructed using FBP, ASIR, and MBIR. Matching images were randomized and independently reviewed by chest radiologists. Subjective assessment of disease presence and radiological diagnosis was made on a 10-point scale. In addition, semi-quantitative results were compared for the extent of abnormalities estimated to the nearest 5% of parenchymal involvement. RESULTS: In the phantom study, ASIR was comparable to FBP in terms of spatial resolution. However, for MBIR, the spatial resolution was greatly decreased under 10 mA. In the patient study, the detection of the presence of disease was not significantly different. The values for area under the curve for detection of DILD by HRCT, FBP, ASIR, and MBIR were as follows: 0.978, 0.979, 0.972, and 0.963. LDCT images reconstructed with FBP, ASIR, and MBIR tended to underestimate reticular or honeycombing opacities (-2.8%, -4.1%, and -5.3%, respectively) and overestimate ground glass opacities (+4.6%, +8.9%, and +8.5%, respectively) compared to the HRCT images. However, the reconstruction methods did not differ with respect to radiologic diagnosis. CONCLUSION: The diagnostic performance of LDCT with MBIR was similar to that of HRCT in typical DILD cases. However, caution should be exercised when comparing disease extent, especially in follow-up studies with IR.
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Humans , Diagnosis , Ethics Committees, Research , Follow-Up Studies , Glass , Lung Diseases, Interstitial , Methods , Prospective Studies , Retrospective Studies , Thorax , Tomography, X-Ray ComputedABSTRACT
Background: Dental radiography is an important tool for detection of caries and digital radiography is the latest advancement in this regard. Spatial resolution is a characteristic of digital receptors used for describing the quality of images. Aim: This study was aimed to compare the diagnostic accuracy of two digital radiographic systems with three different resolutions for detection of noncavitated proximal caries. Settings and Design: Diagnostic accuracy. Materials and Methods: Seventy premolar teeth were mounted in 14 gypsum blocks. Digora® Optime and RVG Access were used for obtaining digital radiographs. Six observers evaluated the proximal surfaces in radiographs for each resolution in order to determine the depth of caries based on a 4‑point scale. The teeth were then histologically sectioned, and the results of histologic analysis were considered as the gold standard. Data were entered using SPSS version 18 software and the Kruskal–Wallis test was used for data analysis. P <0.05 was considered as statistically significant. Results: No significant difference was found between different resolutions for detection of proximal caries (P > 0.05). RVG access system had the highest specificity (87.7%) and Digora® Optime at high resolution had the lowest specificity (84.2%). Furthermore, Digora® Optime had higher sensitivity for detection of caries exceeding outer half of enamel. Judgment of oral radiologists for detection of the depth of caries had higher reliability than that of restorative dentistry specialists. Conclusion: The three resolutions of Digora® Optime and RVG access had similar accuracy in detection of noncavitated proximal caries.
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Bicuspid/analysis , Dental Caries/diagnosis , Dental Caries/diagnostic imaging , Dental Caries Activity Tests/methods , Radiography, Dental, Digital/methods , Tomography, Spiral Computed/methodsABSTRACT
To put forward spatial resolution detection requirements of 64-slice helical CT based on analyzing the present situation of CT spatial resolution detection. The requirements for spatial resolution in the existing industrial standards were analyzed, and some test data were used to prove the deficiency of the standards. Spatial resolu-tion detection requirements were proposed for 64-slice helical CT, and the factors affecting spatial resolution were ex-plored. The deficiencies in the original standards were eliminated. The proposed requirements may facilitate the spatial resolution detection of 64-slice CT, and thus can enhance image quality for clinical diagnosis and treatment.
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Positron Emission Tomography (PET) in small animals has actually achieved spatial resolution round about 1 mm and currently there are under study different approaches to improve this spatial resolution. One of them combines PET technology with Compton Cameras. This paper presents the idea of the so called "PET-Compton" systems and has included comparative evaluation of spatial resolution and global efficiency in both PET and PET-Compton system by means of Monte Carlo simulations using Geant4 code. Simulation was done on a PET-Compton system made-up of LYSO-LuYAP scintillating detectors of particular small animal PET scanner named "Clear-PET"and for Compton detectors based on CdZnTe semiconductor. A group of radionuclides that emits a positron (e+) and Y quantum almost simultaneously and fulfills some selection criteria for their possible use in PET-Compton systems for medical and biological applications were studied under simulation conditions. By means of analytical reconstruction using SSRB (Single Slide Rebinning) method were obtained superior spatial resolution in PET-Compton system for all tested radionuclides (reaching sub-millimeter values of for 22Na source). However this analysis done by simulation have shown limited global efficiency values in "PET-Compton" system (in the order of 10-5 - 10-5 %) instead of values around 5-10-1% % that have been achieved in PET system.
En la actualidad la tomografía por emisión de positrones (PET en pequeños animales ha alcanzado valores de resolución espacial cercanos a mm y en estos momentos se encuentran bajo estudio diferentes aproximaciones para mejorar dicha resolución espacial. Una de ellas combina la tecnología PET con las cámaras Compton. Este trabajo presenta la idea del denominado Sistema "PET-Compton" e incluye una evaluación comparativa de la resolución espacial y la eficiencia global de los sistemas PET y PET-Compton por medio de la simulación por Monte Carlo, utilizando el código Geant4. La simulación fue realizada en un sistema PET-Compton compuesto por detectores centellantes de LYSO-LUYAP de un específico y pequeño escáner PET denominado "Clear-PET" y para detectores Compton en base al semiconductor CdZnTe. Se estudiaron bajo las condiciones de simulación un grupo de radionúclidos que emiten un positrón (e+) y un cuanto gamma casi simultáneamente y cumplen ciertos criterios de selección para su posible utilización en aplicaciones médicas y biomédicas de los sistemas PET-Compton. Por medio de la reconstrucción analítica, empleando el método de reordenamiento de cortes simples (SSRB) se obtuvo una resolución espacial superior para el sistema PET-Compton en todos los radionúclidos de prueba, que alcanzó valores por debajo del milímetro para la fuente de 22Na. Sin embargo, el análisis realizado por medio de la simulación demostró valores limitados de eficiencia global para el sistema PET-Compton (del orden de 10-5-10-5%) en contraposición a los valores cercanos a 5-10-1 % que se alcanzaron para el sistema PET.
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OBJECTIVE: To evaluate the efficacy for spatial resolution and radiation dose of a small-field digital mammographic imaging system using parabolic polycapillary optics. MATERIALS AND METHODS: We developed a small-field digital mammographic imaging system composed of a CCD (charge coupled device) detector and an X-ray source coupled with parabolic polycapillary optics. The spatial resolution and radiation dose according to various filters were evaluated for a small-field digital mammographic imaging system. The images of a test standard phantom and breast cancer tissue sample were obtained. RESULTS: The small-field digital mammographic imaging system had spatial resolutions of 12 lp/mm with molybdenum and rhodium filters with a 25-micrometer thickness. With a thicker molybdenum filter (100 micrometer thick), the system had a higher spatial resolution of 11 lp/mm and contrast of 0.48. The radiation dose for a rhodium filter with a 25-micrometer thickness was 0.13 mGy within a 10-mm-diameter local field. A larger field image greater than 10 mm in diameter could be obtained by scanning an object. On the small-field mammographic imaging system, microcalcifications of breast cancer tissue were clearly observed. CONCLUSION: A small-field digital mammographic imaging system with parabolic polycapillary optics may be a useful diagnostic tool for providing high-resolution imaging with a low radiation dose for examination of local volumes of breast tissue.
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Humans , Equipment Design , Mammography/instrumentation , Molybdenum , Optics and Photonics/instrumentation , Phantoms, Imaging , Radiographic Image Enhancement/instrumentation , RhodiumABSTRACT
The purpose of this study is to optimize a parallel-hole collimator for small gamma camera having the pixellated crystal array and evaluate the effect of crystal-collimator misalignment on the image quality using a simulation tool GATE (Geant4 Application for Tomographic Emission). The spatial resolution and sensitivity were measured for the various size of hexagonal-hole and matched square-hole collimators with a Tc-99m point source and the uniformity of flood image was estimated as a function of the angle between crystal array and collimator by misalignment. The results showed that the spatial resolution and sensitivity were greatly improved by using the matched collimator and the uniformity was reduced by crystal-collimator misalignment.
Subject(s)
Gamma CamerasABSTRACT
AIM To investigate actions of total paeony glycoside(TPG) on learning and memory capacity and related products of metabolism of senile mice induced by D galactose. METHODS The subacute senile mouse models induced by injection of D galactose subcutaneously were used. RESULTS TPG could improve the learning and memory capacity of model mice in shuttle test and enhance spatial resolution in water maze test. TPG not only reduced the content of monoamine oxidase(MAO) and inhibited the decrease of cholinesterase(CHE) significantly, but also lessened the level of malondialdehyde(MDA) and inhibited the decrease of superoxide dismutase(SOD) in cerebrum of model mice. TPG still promoted the recovery of lobar atrophy and hypoimmunity of senile mice remarkedly. CONCLUSION TPG possesses obvious effects of improvement on learning, spatial resolution and delaying senility.