ABSTRACT
Advanced radiotherapy technology enables the dose to more accurately conform to the tumor target area of the patient, providing accurate treatment for the patient, but the gradient of the patient's radiation dose at the tumor edge is getting larger, which putting forward higher requirements for radiotherapy dose verification. The dose verification system software KylinRay-Dose4D can verify the patient's pre-treatment plan and the in vivo/on-line dose during the patient's treatment, providing important reference for the physicist to modify the radiotherapy plan and ensuring that the patient receives accurate treatment. This study introduces the overall design and key technologies of KylinRay-Dose4D, and tests the pre-treatment plan dose checking calculation and 2D/3D dose verification through clinical cases. The test results showed that the 2D/3D gamma pass rate (3 mm/3%) of KylinRay-Dose4D reconstructed dose compared with TPS plan dose and measured dose is larger than 95%, which indicating that the reconstructed dose of KylinRay-Dose4D meets the requirement of clinical application.
Subject(s)
Humans , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted/methods , Radiotherapy, Intensity-Modulated/methods , Software , Neoplasms , Phantoms, Imaging , Radiometry/methodsABSTRACT
OBJECTIVE@#Current mainstream PET scattering correction methods are introduced and evaluated horizontally, and finally, the existing problems and development direction of scattering correction are discussed.@*METHODS@#Based on NeuWise Pro PET/CT products of Neusoft Medical System Co. Ltd. , the simulation experiment is carried out to evaluate the influence of radionuclide distribution out of FOV (field of view) on the scattering estimation accuracy of each method.@*RESULTS@#The scattering events produced by radionuclide out of FOV have an obvious impact on the spatial distribution of scattering, which should be considered in the model. The scattering estimation accuracy of Monte Carlo method is higher than single scatter simulation (SSS).@*CONCLUSIONS@#Clinically, if the activity of the adjacent parts out of the FOV is high, such as brain, liver, kidney and bladder, it is likely to lead to the deviation of scattering estimation. Considering the Monte Carlo scattering estimation of the distribution of radionuclide out of FOV, it's helpful to improve the accuracy of scattering distribution estimation.
Subject(s)
Positron Emission Tomography Computed Tomography , Scattering, Radiation , Computer Simulation , Brain , Monte Carlo Method , Phantoms, Imaging , Image Processing, Computer-AssistedABSTRACT
Objective: To recognize the usefulness of incorporating Three-Dimensional models of standardized humans in electronic health records, in the context of the development of a teledentistry web platform designed for the attention of the elderly population in COVID-19 pandemic context. Material and Methods: A teledentistry web platform designed with different modules for clinical records. Through a new user-computer interface with a standardized virtual 3D phantom, an extraoral physical examination, an intraoral examination section was modeled. A label-associated marker is allowed to record descriptive aspects of the findings. A 3D odontogram represents multiple patient's conditions for each of the 32 dental positions. Results: From a total of 135 patients registered on the platform, 51 markers and 33 photographs associated with the surface of the virtual 3D phantoms were recorded. For the Location parameter: Hard palate 27.6%, inserted gingiva 15.7%, tongue 15.6%. For the Type of lesion parameter (according to the information entered in the pathology selector): unidentified 35.3%, sub-prosthetic stomatitis 23.5%, irritative fibroma 9.8%. Through the registration of the exact location of the finding in the virtual phantom by a 3D marker, the 3D modeling of the oral pathologies contributed to a better diagnosis, improving the remote communication between the attending dentist and specialists. Conclusion: The combination of the 3D modeling and anatomical-referencing in a teledentistry platform can become a powerful tool for the dental practice, due to their utility and specificity.
Objetivo: Reconocer la utilidad de incorporar modelos tridimensionales de humanos estandarizados en registros electrónicos de salud, en el contexto del desarrollo de una plataforma web de teleodontología diseñada para la atención de la población adulta mayor en contexto de pandemia por COVID-19. Material y Métodos: Una plataforma web de teleodontología diseñada con diferentes módulos para historias clínicas. A través de una nueva interfaz usuario-computadora con un fantoma 3D virtual estandarizado, se modeló un examen físico extraoral, una sección de examen intraoral. Se permite un marcador asociado a la etiqueta para registrar aspectos descriptivos de los hallazgos. Un odontograma 3D representa múltiples condiciones del paciente para cada una de las 32 posiciones dentales.Resultados: De un total de 135 pacientes registrados en la plataforma, se registraron 51 marcadores y 33 fotografías asociadas a la superficie de los fantomas virtuales 3D. Para el parámetro Ubicación: Paladar duro 27,6%, encía insertada 15,7%, lengua 15,6%. Para el parámetro Tipo de lesión (según la información ingresada en el selector de patología): no identificado 35,3%, estomatitis subprotésica 23,5%, fibroma irritativo 9,8%. A través del registro de la ubicación exacta del hallazgo en el fantoma virtual mediante un marcador 3D, el modelado 3D de las patologías orales contribuyó a un mejor diagnóstico, mejorando la comunicación remota entre el odontólogo tratante y los especialistas. Conclusión: La combinación del modelado 3D y la referenciación anatómica en una plataforma de teleodontología puede convertirse en una poderosa herramienta para la práctica odontológica, debido a su utilidad y especificidad.
Subject(s)
Humans , Telemedicine/methods , Imaging, Three-Dimensional/instrumentation , Pandemics , Teledentistry , COVID-19 , Phantoms, Imaging , Electronic Health RecordsABSTRACT
OBJECTIVE@#To propose an adaptive weighted CT metal artifact reduce algorithm that combines projection interpolation and physical correction.@*METHODS@#A normalized metal projection interpolation algorithm was used to obtain the initial corrected projection data. A metal physical correction model was then introduced to obtain the physically corrected projection data. To verify the effectiveness of the method, we conducted experiments using simulation data and clinical data. For the simulation data, the quantitative indicators PSNR and SSIM were used for evaluation, while for the clinical data, the resultant images were evaluated by imaging experts to compare the artifact-reducing performance of different methods.@*RESULTS@#For the simulation data, the proposed method improved the PSNR value by at least 0.2 dB and resulted in the highest SSIM value among the methods for comparison. The experiment with the clinical data showed that the imaging experts gave the highest scores of 3.616±0.338 (in a 5-point scale) to the images processed using the proposed method, which had significant better artifact-reducing performance than the other methods (P < 0.001).@*CONCLUSION@#The metal artifact reduction algorithm proposed herein can effectively reduce metal artifacts while preserving the tissue structure information and reducing the generation of new artifacts.
Subject(s)
Algorithms , Artifacts , Image Processing, Computer-Assisted/methods , Metals , Phantoms, Imaging , Tomography, X-Ray Computed/methodsABSTRACT
Ultrasound guided percutaneous interventional therapy has been widely used in clinic. Aiming at the problem of soft tissue deformation caused by probe contact force in robot-assisted ultrasound-guided therapy, a real-time non-reference ultrasound image evaluation method considering soft tissue deformation is proposed. On the basis of ultrasound image brightness and sharpness, a multi-dimensional ultrasound image evaluation index was designed, which incorporated the aggregation characteristics of the organization. In order to verify the effectiveness of the proposed method, ultrasound images of four different models were collected for experiments, including prostate phantom, phantom with cyst, pig liver tissue, and pig liver tissue with cyst. In addition, the correlation between subjective and objective evaluations was analyzed based on Spearman's rank correlation coefficient. Experimental results showed that the average evaluation time of a single image was 68.8 milliseconds. The evaluation time could satisfy real-time applications. The proposed method realizes the effective evaluation of real-time ultrasound image quality in robot-assisted therapy, and has good consistency with the evaluation of supervisors.
Subject(s)
Animals , Male , Cysts , Phantoms, Imaging , Swine , Ultrasonography/methodsABSTRACT
OBJECTIVE@#To propose a nonlocal spectral similarity-induced material decomposition network (NSSD-Net) to reduce the correlation noise in the low-dose spectral CT decomposed images.@*METHODS@#We first built a model-driven iterative decomposition model for dual-energy CT, optimized the objective function solving process using the iterative shrinking threshold algorithm (ISTA), and cast the ISTA decomposition model into the deep learning network. We then developed a novel cost function based on the nonlocal spectral similarity to constrain the training process. To validate the decomposition performance, we established a material decomposition dataset by real patient dual-energy CT data. The NSSD-Net was compared with two traditional model-driven material decomposition methods, one data-based material decomposition method and one data-model coupling-driven material decomposition supervised learning method.@*RESULTS@#The quantitative results showed that compared with the two traditional methods, the NSSD-Net method obtained the highest PNSR values (31.383 and 31.444) and SSIM values (0.970 and 0.963) and the lowest RMSE values (2.901 and 1.633). Compared with the datamodel coupling-driven supervised decomposition method, the NSSD-Net method obtained the highest SSIM values on water and bone decomposed results. The results of subjective image quality assessment by clinical experts showed that the NSSD-Net achieved the highest image quality assessment scores on water and bone basis material (8.625 and 8.250), showing significant differences from the other 4 decomposition methods (P < 0.001).@*CONCLUSION@#The proposed method can achieve high-precision material decomposition and avoid training data quality issues and model unexplainable issues.
Subject(s)
Humans , Algorithms , Image Processing, Computer-Assisted/methods , Phantoms, Imaging , Signal-To-Noise Ratio , Tomography, X-Ray Computed/methods , WaterABSTRACT
Clinical applications of cone-beam breast CT(CBBCT) are hindered by relatively higher radiation dose and longer scan time. This study proposes sparse-view CBBCT, i.e. with a small number of projections, to overcome the above bottlenecks. A deep learning method - conditional generative adversarial network constrained by image edges (ECGAN) - is proposed to suppress artifacts on sparse-view CBBCT images reconstructed by filtered backprojection (FBP). The discriminator of the ECGAN is the combination of patchGAN and LSGAN for preserving high frequency information, with a modified U-net as the generator. To further preserve subtle structures and micro calcifications which are particularly important for breast cancer screening and diagnosis, edge images of CBBCT are added to both the generator and the discriminator to guide the learning. The proposed algorithm has been evaluated on 20 clinical raw datasets of CBBCT. ECGAN substantially improves the image qualities of sparse-view CBBCT, with a performance superior to those of total variation (TV) based iterative reconstruction and FBPConvNet based post-processing. On one CBBCT case with the projection number reduced from 300 to 100, ECGAN enhances peak-signal-to-noise ratio (PSNR) and structural similarity (SSIM) on FBP reconstruction from 24.26 and 0.812 to 37.78 and 0.963, respectively. These results indicate that ECGAN successfully reduces radiation dose and scan time of CBBCT by 1/3 with only small image degradations.
Subject(s)
Humans , Algorithms , Breast , Cone-Beam Computed Tomography , Image Processing, Computer-Assisted , Phantoms, Imaging , Tomography, X-Ray ComputedABSTRACT
There is a shared problem in current optical imaging technologies of how to obtain the optical parameters of biological tissues with complex profiles. In this work, an imaging system for obtaining the optical parameters of biological tissues with complex profile was presented. Firstly, Fourier transformation profilometry was used for obtaining the profile information of biological tissues, and then the difference of incident light intensity at different positions on biological tissue surface was corrected with the laws of illumination, and lastly the optical parameters of biological tissues were achieved with the spatial frequency domain imaging technique. Experimental results indicated the proposed imaging system could obtain the profile information and the optical parameters of biological tissues accurately and quickly. For the slab phantoms with height variation less than 30 mm and angle variation less than 40º, the maximum relative errors of the profile uncorrected optical parameters were 46.27% and 72.18%, while the maximum relative errors of the profile corrected optical parameters were 6.89% and 10.26%. Imaging experiments of a face-like phantom and a human's prefrontal lobe were performed respectively, which demonstrated the proposed imaging system possesses clinical application value for the achievement of the optical parameters of biological tissues with complex profiles. Besides, the proposed profile corrected method can be used to combine with the current optical imaging technologies to reduce the influence of the profile information of biological tissues on imaging quality.
Subject(s)
Humans , Diagnostic Imaging , Light , Optical Imaging , Phantoms, ImagingABSTRACT
Dose verification is carried out on the individualized three-dimensional phantom based on 3D printing technology, which simulates the anatomical structure of human body, contour shape, tumor anatomical structure and other dangerous organs to the greatest extent, and produces a reasonable and effective dose validation phantom. According to the need to obtain effective patient data, import Mimics software to reconstruct the parts of the body and its surrounding tissues and organs that need to be measured, and make them into three-dimensional shell components. The 3D printing is used to assemble and fill the equivalent tissue, and then the body phantom is made. The phantom was scanned by CT and the data was transmitted to TPS system. The previously completed treatment plan was transplanted to the phantom. The phantom was placed according to the patient's location information, irradiated and measured data. The three-dimensional shell assembly is completely reconstructed according to the patient's data, and the contour difference is not significant. The shell is filled with tissue radiation equivalent material whose CT value is the same as the average CT value of the shell volume. The CT image data show that the radiation equivalence of the phantom is similar to the actual tissue of the patient, and the equivalent dose distribution conforms to the conventional treatment range. It can provide a reliable means of dose verification for the accurate design of intensity modulated radiation therapy.
Subject(s)
Humans , Phantoms, Imaging , Printing, Three-Dimensional , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-ModulatedABSTRACT
Virtual monochromatic images (VMI) that reconstructed on dual-energy computed tomography (DECT) have further application prospects in radiotherapy, and there is still a lack of clinical dose verification. In this study, GE Revolution CT scanner was used to perform conventional imaging and gemstone spectral imaging on the simulated head and body phantom. The CT images were imported to radiotherapy treatment planning system (TPS), and the same treatment plans were transplanted to compare the CT value and the dose distribution. The results show that the VMI can be imported into TPS for CT value-relative electron density conversion and dose calculation. Compared to conventional images, the VMI varies from 70 to 140 keV, has little difference in dose distribution of 6 MV photon treatment plan.
Subject(s)
Electrons , Phantoms, Imaging , Tomography Scanners, X-Ray Computed , Tomography, X-Ray ComputedABSTRACT
In order to suppress the geometrical artifacts caused by random jitter in ray source scanning, and to achieve flexible ray source scanning trajectory and meet the requirements of task-driven scanning imaging, a method of free trajectory cone-beam computed tomography (CBCT) reconstruction is proposed in this paper. This method proposed a geometric calibration method of two-dimensional plane. Based on this method, the geometric calibration phantom and the imaging object could be simultaneously imaged. Then, the geometric parameters could be obtained by online calibration method, and then combined with the geometric parameters, the alternating direction multiplier method (ADMM) was used for image iterative reconstruction. Experimental results showed that this method obtained high quality reconstruction image with high contrast and clear feature edge. The root mean square errors (RMSE) of the simulation results were rather small, and the structural similarity (SSIM) values were all above 0.99. The experimental results showed that it had lower image information entropy (IE) and higher contrast noise ratio (CNR). This method provides some practical value for CBCT to realize trajectory freedom and obtain high quality reconstructed image.
Subject(s)
Algorithms , Calibration , Cone-Beam Computed Tomography , Image Processing, Computer-Assisted , Phantoms, ImagingABSTRACT
OBJECTIVES@#To study the feasibility of ArcCHECK-3DVH system in dosimetric verification for stereotactic body radiaotherapy (SBRT) with flattening filter free (FFF) model.@*METHODS@#SBRT treatment plans for 57 patients were introduced into ArcCHECK phantom and recalculated. The calculated dose distribution of treatment planning system and the measured dose distribution of ArcCHECK phantom were compared by γ analysis. Then the 3 dimensional dose distribution of target and organs at risk was reconstructed by 3DVH software. The reconstructed dose and calculated dose with treatment planning system (TPS) were compared, and the dose volume γ pass rate and deviation of dose volume parameters to the target and organs at risk were quantitatively valuated.@*RESULTS@#Based on the threshold criteria (3%, 3 mm, 10%), namely the deviation of measuring points between the planned value and the measured value was less than 3%, and the proportion of points with similar values in the plane or sphere with the center of the point and the radius of 3 mm was 10%, the relative and absolute dose pass rates of SBRT treatment plans in ArcCHECK system via γ analysis were greater than 95%. Based on the stricter threshold criteria (2%, 2 mm, 10%), the relative and absolute dose pass rates of SBRT treatment plan in ArcCHECK system via γ analysis were about 93%. In 3DVH dose verification, the γ pass rate of target and organs at risk was exceed 97%, and the deviations in 3DVH of the target and organs at risk were less than ±5%.@*CONCLUSIONS@#The ArcCHECK-3DVH system in dose verification can provide more comprehensive dose distribution information to reasonably evaluate the SBRT plan, with more significance for guiding clinical treatment.
Subject(s)
Humans , Phantoms, Imaging , Quality Assurance, Health Care , Radiometry , Radiosurgery , Radiotherapy Dosage , Radiotherapy Planning, Computer-Assisted , Radiotherapy, Intensity-ModulatedABSTRACT
OBJECTIVE@#To investigate the pre-treatment preventive maintenance and quality control procedure of MRI system and transcranial MRI-guided focused ultrasound (TcMRgFUS) treatment system by monitoring quality control of these two systems.@*METHODS@#The general performance index and image quality control index of MRI system, as well as the quality assurance program of TcMRgFUS EXABLATE 4000 system were tested and recorded.@*RESULTS@#The general performance index and image quality control index of MRI system met requirements.@*CONCLUSIONS@#Through system detection, the system performance could be monitored, ensuring the accuracy and safety of surgery.
Subject(s)
Hyperthermia, Induced , Magnetic Resonance Imaging , Phantoms, Imaging , Quality ControlABSTRACT
Accurate CT simulation is the key link of precision radiotherapy, and the performance of the localization couch of CT simulator directly affects the accuracy of radiotherapy. With the rapid development of precision radiotherapy, conventional large aperture radiotherapy special CT simulator is difficult to meet the needs of precision radiotherapy localization, so most radiotherapy centers choose high-end diagnostic CT machines equipped with a flat tabletop for radiotherapy localization. In clinical work, the performance testing of the CT simulator localization couch is easy to be ignored. In addition, there are some problems such as insufficient precision in transforming the cradle-shaped couch top of diagnostic CT into a special flat couch top for radiotherapy. This paper provided an in-depth description of the improved design and performance test of the localization couch of the first special GE Revolution CT simulator for radiotherapy introduced by West China Hospital of Sichuan University. After the improvement, all the acceptance tests of the localization couch are in line with the standard, and the performance meets the high-precision radiotherapy localization needs of patients with different body weight in the center.
Subject(s)
Humans , China , Computer Simulation , Phantoms, Imaging , Radiotherapy Planning, Computer-Assisted , Tomography, X-Ray ComputedABSTRACT
Magnetic resonance based electrical properties tomography (MREPT) is a different method from proton density imaging, Bloch-Siegert shift (BSS) is used in this paper to reconstruct the radiofrequency (RF) field amplitude and calculate the distribution of the permittivity constant. The phase of the RF field is approximated by the phase component of the magnetization intensity, and the conductivity distribution is calculated. In the experiment, Bruker 7.0 T magnetic resonance device was used to image two water models and in vivo Balb/c mice to obtain the image of electrical characteristics. Experimental results show that the Bloch-siegert B1+ image is significantly more efficient than the double-angle B1+ image. The study can provide a reference for selecting appropriate B1 mapping technology for B1 field imaging of electrical characteristics organizations, and provide basic research support for promoting the practical application of magnetic resonance characteristics.
Subject(s)
Animals , Mice , Algorithms , Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Phantoms, Imaging , TomographyABSTRACT
The complex electromagnetic field environments in magnetic resonance imaging system(MRI) can have a significant impact on patients carrying implants, the RF heating problems being particularly important. To ensure the safety of the patients, it is necessary to understand the distribution of tissue temperature in the MRI environment and its changes over time. Based on the analysis of tissue temperature rise in MRI, this paper constructs a bird cage coil for generating RF field in MRI system, and constructs ASTM standard/improved phantom and single-cavity pacemaker finite element models, use time-domain finite difference (FDTD) to simulate. Firstly, the correctness of the simulation software and simulation method was validated according to the method of ISO. Then the distribution of the electric field, SAR and temperature field and the temperature change with time were calculated in the environment of 64 MHz, 2 W/kg. The difference in temperature rise with blood heat exchange and no blood heat exchange (standard/improved phantom) was specifically compared. The simulation results show that there are electric field and SAR hotspots near the electrode tip, the wire tail and the case of pacemaker. There are high SAR values on both sides of the phantom, and the shorter the distance from the coil, the higher the SAR. The temperature field distribution is similar to the SAR distribution; the temperature is higher in the area around the end of the wire and the case of pacemaker because the heat accumulation is higher around this area. At the same time, blood heat exchange can reduce the temperature rise to a certain extent.
Subject(s)
Humans , Electromagnetic Fields , Magnetic Resonance Imaging , Models, Theoretical , Phantoms, Imaging , Prostheses and Implants , TemperatureABSTRACT
Fluorescent Diffuse Optical Tomography (FDOT) is an emerging imaging method with great prospects in fields of biology and medicine. However, the current solutions to the forward problem in FDOT are time consuming, which greatly limit the application. We proposed a method for FDOT based on Lattice Boltzmann forward model on GPU to greatly improve the computational efficiency. The Lattice Boltzmann Method (LBM) was used to construct the optical transmission model. This method separated the LBM into collision, streaming and boundary processing processes on GPUs to perform the LBM efficiently, which were local computational and inefficient on CPU. The feasibility of the proposed method was verified by the numerical phantom and the physical phantom experiments. The experimental results showed that the proposed method achieved the best performance of a 118-fold speed up under the precondition of simulation accuracy, comparing to the diffusion equation implemented by Finite Element Method (FEM) on CPU. Thus, the LBM on the GPU may efficiently solve the forward problem in FDOT.
Subject(s)
Computers , Fluorescence , Phantoms, Imaging , Tomography, Optical/methodsABSTRACT
OBJECTIVE@#To explore the application value of MAR algorithm in metal artifact removal of CT simulator.@*METHODS@#CT phantom with titanium plate was scanned using conventional algorithms and MAR algorithms, respectively. Artifact index(AI), contrast-to-noise ratio(CNR) and AI values at different slices were used to analyze the artifact images.@*RESULTS@#In artifact index, MAR algorithm (10.28±2.60) is significantly lower than conventional algorithm (20.65±5.04); In contrast-to-noise ratio index, MAR algorithm (7.81±1.12) is better than conventional algorithm (5.61±1.36). The above indicators were statistically significant in both algorithms (P<0.01). In the slices affected by metal artifacts, the artifact index decreased by 21.72%~88.40% after the MAR algorithm.@*CONCLUSIONS@#MAR algorithm can significantly reduce the metal artifacts and improve the clinical value of CT data.
Subject(s)
Algorithms , Artifacts , Metals , Phantoms, Imaging , Titanium , Tomography, X-Ray ComputedABSTRACT
The Dual energy X-ray absorptiometry is the most commonly used for measuring bone mineral density. This method involves core clinical functions, phantom and database. This article discusses the three key issues of dual energy X-ray absorptiometry evaluation, including core clinical functions, phantom and database. This article aims at helping manufacturers to scientifically carry out relevant processes during research and development and also manufacturers may refer to this article when they apply for registration.
Subject(s)
Humans , Absorptiometry, Photon , Bone Density , Databases, Factual , Phantoms, ImagingABSTRACT
To explore a method for calculating water equivalent diameter () based on localizer CT images for calculation of the size specific dose estimates (SSDE).GE Revolution CT and LightSpeed VCT were used to scan CT dose index phantoms 16 cm and 32 cm in diameter at the tube voltages of 80, 100 and 120 kV to obtain the axial image and anteroposterior localizer radiograph. According to the definition of CT Hounsfield unit, the axial images were used to calculate the conversion factors that convert the phantom thickness to water equivalent thickness. The gray value of the localizer radiograph and the water equivalent thickness were calibrated with a linear equation, and the parameters of the calibration were used to calculate the water equivalent thickness. The method was verified using 2 CT dose index phantoms and in 22 patients undergoing chest and abdominal CT examination.Comparison of the water equivalent diameter () based on the localizer radiograph and axial image of the 2 phantoms showed that the percentage difference between from the axial images and from the localizer radiograph was below 3%. The trend of variations with location in the two methods was sonsistent. The difference in in intermediate region of interest between the axial image and the localizer radiograph from the 22 patients was below 6.6%. With the mean in the ROI, the maximum percentage difference was 7.5%.Calibration of the gray value of the localizer radiograph and the water equivalent thickness using the axial image and localizer radiograph of CT dose index phantoms allows quick calculation of the SSDE based on the parameters of calibration.