Diagnosis of pulmonary artery sarcoma and differential diagnosis of pulmonary embolism with double-detector spectral CT: a case report / 中国医师杂志

Objective:The differential diagnosis of pulmonary artery sarcoma (PAS) and pulmonary embolism (PE) by double-detector spectral computerized tomography (CT) provides a new way to improve the detection rate of PAS and reduce the misdiagnosis rate.Methods:In the way of retrospective study, the Philips Nebula Workstation (ISP) was used to reconstruct electron density map, iodine density map and spectral curve in the spectral CT plain scan and enhancement of the PAS patient. In the plain scan image, the low density areas of the ascending aorta and the right pulmonary trunk were selected to measure their electronic density values. In the chest enhancement image, the iodine density of PAS area and PE area were measured respectively, and the spectral curves of PSA area and PE area were compared.Results:The electron density of the ascending aorta and the right pulmonary trunk in the low density area of the PAS patient during the plain scan of spectral CT were 104.4% EDW (relative to the percentage of the electron density of water) and 102.2% EDW, respectively, which were lower than those in the normal ascending aorta area. The fusion image of mixed energy and electron density clearly reflected the scope of the lesion. The iodine density in PAS area was 1.89 mg/ml, and the iodine density in PE area was 0.03 mg/ml during the enhancement phase. The iodine uptake in PAS area was significantly higher than that in PE area. The slope of PAS region was 2.08, and the slope of PE region was -1.86. The slopes of the two spectral curves were inconsistent.Conclusions:The electronic density, iodine density and spectral curve measured by double-detector spectral CT may provide powerful imaging basis for the diagnosis of PAS and the differentiation of PAS from PE, which is helpful for the early diagnosis of the lesions, and also provide basis for the biopsy location of the mixed lesions of PAS and PE.

The value of virtual monoenergetic images and electron density map derived from dual-layer spectral detector CT in differentiating benign from malignant pulmonary ground glass nodules / 中华放射学杂志

Objective:To investigate the clinical value of virtual monoenergetic images (VMI) and electron density map (EDM) derived from the dual-layer spectral detector CT (DLCT) in the differential diagnosis of benign and malignant pulmonary ground glass nodules (GGN).Methods:From July 2019 to August 2020, a total of 65 patients with lung GGN (27 benign GGNs and 38 malignant GGNs) confirmed by pathology were retrospectively enrolled in Gulou Clinical Medical College of Nanjing Medical University. All the patients underwent DLCT plain scanning within two weeks before the surgery. The conventional 120 kVp polyenergetic image (PI), EDM and 40-80 keV VMI were reconstructed. The differences of CT and electron density (ED) values between benign and malignant lesions on different images were compared by Mann-Whitney U test. Independent t-test was used to compare the lesion size and χ 2 test was used to analyze the CT features (including lesion location, shape, edge, internal structure, adjacent structure, nodule type) between benign and malignant lesions. Receiver operating characteristic (ROC) curve was used to analyze the efficacy of different energy spectrum quantitative parameters in the differential diagnosis of benign and malignant GGN. The statistically significant CT signs and energy spectrum quantitative parameters were analyzed by logistic regression analysis to find out the independent risk factors of malignant GGN, and then ROC curve analysis was performed for each independent risk factor alone or in combination. Results:There were significant differences in lesion shape, spiculation, lobulation, location and size between benign and malignant groups ( P<0.05). The CT value of pulmonary GGN in PI, 40-80 keV VMI and the ED value in EDM were statistically different between benign and malignant lesions ( P<0.05). The area under ROC curve (AUC) were 0.680, 0.682, 0.683, 0.686, 0.694, 0.676 and 0.722, respectively, among which the ED value had the highest AUC. Binary logistic regression analysis was carried out with GGN shape, spiculation, lobulation, location, size, ED value and CT value in PI, 40-80 keV VMI as independent variables, and malignant GGN as dependent variables. The results showed that ED value (OR=1.045, 95%CI 1.001-1.090, P=0.044), lesion size (OR=1.582, 95%CI 1.159-2.158, P=0.004), spiculation sign (OR=11.352, 95%CI 2.379-54.172, P=0.002) were independent risk factors for malignant GGN. ROC curve analysis showed the AUC of ED value, lesion size, spiculation sign and combination of the three for differential diagnosis of benign and malignant GGN were 0.722, 0.772, 0.698 and 0.885. The AUC for the combined parameters was the largest, with sensitivity of 92.1% and specificity of 74.1%. Conclusion:The diagnostic efficacy of EDM is higher than that of other VMI in the differential diagnosis of pulmonary GGN by DLCT images; The efficacy is further improved when EDM is combined with lesion size and spiculation sign for comprehensive diagnosis.

Comportamiento dosimétrico de un sistema de planificación mediante curvas de calibración de densidades electrónicas relativas / Dosimetric behaviour of a planning system through calibration curves of relative electron density

En esta investigación se planteó como objetivo la verificación del comportamiento dosimétrico del Sistema de Planificación de Tratamiento (TPS) de Radioterapia mediante las curvas de calibración de Densidades Electrónicas Relativas (DER). Este estudio se realizó en el Hospital de la Sociedad de Lucha Contra el Cáncer (SOLCA) Núcleo Loja, usando un fantoma antropomorfo CIRS 062M y un tomógrafo Toshiba Activion 16. Para determinar la nueva curva de calibración DER se tomaron los valores de densidades electrónicas especificadas en el manual del fantoma y las Unidades Hounsfield de la imagen tomográfica. Se realizó controles de calidad dosimétricos y verificación dosimétrica en tres casos clínicos: tórax, pelvis y cráneo; para realizar las pruebas dosimétricas se utilizó un acelerador CLINAC CX, cámara de ionización PTW tipo Farmer con volumen sensible de 0,6 cm3 y un electrómetro PTW UNIDOS E. Los resultados mostraron que las medidas para cada inserto del fantoma en ningún caso excedieron los límites establecidos de ± 20 UH, para el tomógrafo y el TPS; las pruebas de control de calidad no superaron el límite máximo de desviaciones en el cálculo de dosis absorbida por el TPS y la obtenida por medición de ± 4 % establecida por la IAEA y las verificaciones dosimétricas en tórax, pelvis y cráneo, determinaron que las desviaciones en el cálculo de la dosis absorbida por el TPS y la obtenida por medición no superaban la tolerancia del ± 5 % establecida por la ICRU.

In this research, the aim was to verify the dosimetric behavior of the Radiotherapy Treatment Planning System (TPS) using the Relative Electron Density (DER) calibration curves. This study was carried out at the SOLCA (Society of Fight Against Cancer) hospital in Loja, using an CIRS model 062M anthropomorphic phantom and a Toshiba Activion 16 tomograph. To determine the new DER calibration curve, the values of the electron densities specified in the manual of the phantom and the Hounsfield Units of the tomographic image were taken. Dosimetric quality controls were made in the location of three clinical cases: thorax pelvis and skull; used a CLINAC CX accelerator was used to perform the dosimetric tests, PTW ionization chamber type Farmer with sensitive volume of 0.6 cm3 and a PTW UNIDOS E electrometer. The results showed that the measurements for each insert of the phantom in no case exceeded the established limits of ± 20 UH, for the tomograph and the TPS; the quality control tests did not exceed the maximum limit of deviations in the calculation of dose absorbed by the TPS and the one obtained by measurement of ± 4% established by the IAEA and the clinical planning in the thorax, pelvis and skull, determine that the deviations in the calculation of the dose absorbed by the TPS and that obtained by measurement, they do not exceed the tolerance of ± 5% established by the ICR.

Method on automatic location of inserts in electron density phantom / 中国医学影像技术

Objective: To investigate automatic location of inserts in the electron density phantom (CIRS 062) based on deep neural network (DCNN). Methods Firstly, four inserts in CIRS 062 were segmented with DCNN model, namely the inhaled lung, the exhaled lung, the solid trabecular bone and the solid dense bone. Then Moore-neighbor tracking algorithm was used to process the segmentation results to obtain the precise segmentation edges. Finally, the other four inserts were located based on the geometric features. Results The results of Dice similarity coefficient were all >0.85, the precision were all >0.81, and F1-measure were all >0.61 based on DCNN. Conclusion The method based on DCNN can realize the automatic positioning of the inserts.

The necessity of inclusion of a virtual treatment couch involved in the XiO treatment planning system / 中华放射医学与防护杂志

Objective To investigate the dosimetric effect of carbon fiber couch through virtual simulation in the XiO treatment planning system (TPS).Methods A treatment couch model of iBEAM evo Extension 650 was scanned with a big bore spiral CT and its contour was stored in the XiO TPS.The attenuation coefficient of couch was obtained by measuring the attenuated dose with and without a solid water phantom on the couch at different gantry angles (100°-180°).The optimal relative electron density (RED) values of the carbon fiber (CF) cover and foam core (FC) were adjusted according to the comparison between measured and simulated attenuation dose.The effects of the couch in the TPS on pass rate were evaluated by Octavius 4D phantom with 10 cases with lung cancer.Results The optimal RED values of CF and FC were 0.75 and 0.10 g/cm3,respectively.The measured attenuation error was the maximal at gantry angle of 120° (4.84％) without the treatment couch in the TPS.The average measured attenuation errors without the couch in the TPS dropped significantly from (2.54 ± 1.48) ％ to (-0.04 ± 0.36) ％ after inclusion of the treatment couch during dose calculation (Z =-3.621,P ＜ 0.05).The three-dimensional dose verification γ pass rate (3 mm/3％) without the couch increased significantly from (91.79± 1.25)％ to (94.74± 1.69)％ after inclusion of the couch in the dose calculation (t =6.027,P ＜ 0.05).Conclusions The effect of couch on the attenuation dose is significant.Inclusion of a virtual model of couch in XiO TPS can simulate the attenuation effect properly and improve the accuracy of dose calculation.

Numerical Simulations to Assess ART and MART Performance for Ionospheric Tomography of Chapman Profiles

ABSTRACT The incomplete geometrical coverage of the Global Navigation Satellite System (GNSS) makes the ionospheric tomographic system an ill-conditioned problem for ionospheric imaging. In order to detect the principal limitations of the ill-conditioned tomographic solutions, numerical simulations of the ionosphere are under constant investigation. In this paper, we show an investigation of the accuracy of Algebraic Reconstruction Technique (ART) and Multiplicative ART (MART) for performing tomographic reconstruction of Chapman profiles using a simulated optimum scenario of GNSS signals tracked by ground-based receivers. Chapman functions were used to represent the ionospheric morphology and a set of analyses was conducted to assess ART and MART performance for estimating the Total Electron Content (TEC) and parameters that describes the Chapman function. The results showed that MART performed better in the reconstruction of the electron density peak and ART gave a better representation for estimating TEC and the shape of the ionosphere. Since we used an optimum scenario of the GNSS signals, the analyses indicate the intrinsic problems that may occur with ART and MART to recover valuable information for many applications of Telecommunication, Spatial Geodesy and Space Weather.

Influence of CT value-electron density transformation curve on radiotherapy dosage for different scanning sites / 医疗卫生装备

Objective To investigate the impacts of the CT value-electron density transformation curves on radiotherapy dosage for different scanning sites.Methods The CT value-electron density transformation curves under head,chest and abdomen modes were obtained with CIRS062 nonuniform equivalent phantom,a CT simulator and the same scanning parameters.Totally 8 patients with glioma,lung cancer or gastric cancer had the radiotherapy dosages calculated with Pinnacle 9.8 TPS and CT value-electron density transformation curve under the three modes,so as to analyze the dosage deviation involving in hop value as well as the dose volume histogram (DVH) for the target area and organs at risk (OAR).Results With the scanning parameters kept the same,the head area had no significant differences in the CT value-electron density transformation curve and exposure dosage with the abdomen area (P＞0.05),while the head and abdomen areas had statistical differences in the CT value-electron density transformation curve with the chest area (P＜0.05).CT values varied greatly at the high-density tissue,while the dosage deviations at the target area and OAR were both less than 2％.Conclusion CT value-electron density transformation curve for different scanning sites has influences on radiotherapy dosage,and head and chest tumors should have the dosage calculation based on the CT value-electron density transformation curve with corresponding scanning modes to ensure dosage computation precision during treatment planning.

Impact factor of relationships between CT value and relative electron density for treatment planning system / 中华放射肿瘤学杂志

ObjectiveTo study the CT values of certain phantoms scanned by various CT scanners with dissimilar parameters.Methods The CT values of tissue equivalent inserts was measured in the TM164 and CIRS-062 phantom scanned by TOSHIBA AQUILIONTM,SIEMENS SOMATOMTMSENSATIONTM 64 and SIEMENS SOMATOMTM SENSATIONTM OPEN with different voltages,currents and slice thicknesses and then the corresponding CT-to-density curves was compared. Results There are no significant differences of CT values with various currents and slice thicknesses and also for low atom number materials scanned by different scanners with various tube voltages.The CT values of high atom number materials have obvious differences scanned with tube voltage,the maximum is about 400 HU.There are also significant differences between CT-density curves of two phantoms in the range from soft tissues to dense bone,the maximum is up to 500 HU.ConclusionsCT-density curves were highly affected by materials of phantoms,scanners and tube voltages.It is necessary to measure the curve with a comfortable phantom and certain scanner to assure the accuracy for dose calculation for treatment planning system.

Funciones de cottorno para árboles como medida e similitud entre campos escalaares moleculares. un estudo de similitud molecular / Contour tree fucctions over molcular scalar fields representations. a moleculaar similarity study / Funções de conorrno de árvore em representaçõe de campos escalares molecularees. um estudo de similaridade molecular

En este trabajo se implementó una función de contorno de un árbol para establecer medidas de similitud molecular. El estudio se realizó con 73 moléculas orgánicas divididas en 8 grupos funcionales optimizadas con un nivel de teoría DFT//B3LYP/6-31G(d,p) a las cuales se les calculó el Potencial Electrostático Molecular y el Laplaciano de la Densidad Electrónica en una rejilla tridimensional. A partir de los valores de estas propiedades, caracterizando y codificando según su topología, se generaron grafos (árboles) que se compararon a través de la función propuesta. La caracterización y clasificación de las moléculas orgánicas con el Potencial Electrostático Molecular muestra una separación correspondiente a moléculas que en su estructura poseen heteroátomos con funciones químicas por lo menos estructuralmente similares, y con el Laplaciano de la Densidad Electrónica se obtuvo como resultado una clasificación acorde con el número de pares de electrones libres asociados a los heteroátomos en las moléculas y a la naturaleza de los átomos que los aportan. Lo anterior evidencia que las funciones de contorno de árbol propuestas en el estudio son una alternativa rápida para clasificar a grosso modo moléculas orgánicas.

In this job, Contour Tree Functions were implemented to establish molecular similarity measures. The study was carried by using 73 organic molecules, divided in 8 functional groups and optimized at theory level DFT//B3LYP/6-31G(d,p). The molecular electrostatic potential and the Laplacian of the electron density in a 3D grid for each one were calculated. From the values of these properties, characterizing and encoding the topology, we generated graphs (trees) that are compared with the proposed function. The characterization and classification of the organic molecules with the molecular electrostatic potential show a separation corresponding to molecules that have heteroatoms in their structure with at least similar chemical functions; with the Laplacian of the electron density we achieved a classification according to the number of free pairs of electrons associated to the heteroatoms in the molecules and to the nature provided by the heteroatoms. This is evidence that Contour Tree Functions proposed in this study are a quick alternative to broadly classify organic molecules.

Neste trabalho, funções de contorno de árvore foram implementadas para estabelecer medidas de similaridade molecular. O estudo foi conduzido com 73 moléculas orgânicas, divididas em 8 grupos funcionais, otimizadas com nível de teoria DFT//B3LYP/6-31G (d,p) para que eles calculassem o potencial eletrostático molecular e o Laplaciano da densidade de elétrons em uma grade tridimensional. A partir dos valores dessas propriedades, caracterização e codificação da topologia, geramos gráficos (árvores) que são comparados com a função proposta. A caracterização e classificação de moléculas orgânicas com potencial eletrostático molecular mostra uma separação correspondente ás moléculas que possuem heteroátomos em sua estrutura com funções químicas, pelo menos, estruturalmente semelhantes. Com o Laplaciano da densidade de elétrons foi obtido como resultado consistente com a classificação do número de pares de elétrons livres associados com heteroátomos nas moléculas e a natureza dos átomos que contribuem. Essa é uma evidência de que as funções de contorno de árvore proposto no estudo são uma alternativa rápida para classificar, grosso modo, moléculas orgânicas.

The Effect of the CT Number for Each CT on Dose Calculation / 의학물리

The CT number corresponds to electron density and its influence on dose calculation was studied. Five kinds of CT scanners were used to obtain images of electron density calibration phantom (Gammex RMI 467). Then the differences between CT numbers for each scanners were +/-2% in homogeneous medium and 9.5% in high density medium. In order to investigate the influence of CT number to dose calculation, patients' thoracic CT images were analyzed. The maximum dose difference was 0.48% for each organ. It acquired the phantom images inserted high density material in the water phantom. Comparing the doses calculated with CT images from each CT scanner, the maximum dose difference was 2.1% in 20 cm in depth. The exact density to CT number conversion according to CT scanner is required to minimize the uncertainty of dose depends on CT number. Especially the each hospital with various CT scanners has to discriminate CT numbers for each CT scanner. Moreover a periodic quality assurance is required for reproducibility of CT number.

The structure of duplex DNA in the nucleosome core particle: An alternative model.

Many studies indirectly indicate that the conformation of in vivo duplex DNA is the double helix. The most direct view, from the X-ray analysis of the nucleosome core particle, has also been interpreted in terms of the double helix structure. However, an alternative possibility exists; that the duplex adopts a metastable side-by-side conformation which readily converts to the double helix on removal of protein. Evidence for the existence of this conformation has been obtained from a reanalysis of the electron density map for the nucleosome particle.