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Objective@#To explore the accurate display method of the local structure of small CT nodules in lung.@*Methods@#Close the automatic radiation dose adjustment technique. Keep the thickness of the phantom was 2 mm, the interval between the phantom layers was 2 mm, the pitch was 1, and the reconstructed convoluted nucleus was B80s. Group A controlled the scanning matrix FOV to be 500 mm×500 mm, 400 mm×400 mm, 300 mm×300 mm, 200 mm×200 mm and 100 mm×100 mm, while group B controlled the scanning matrix FOV to be 500 mm×500 mm. Use these parameters to scan the catphan 500 phantom, a routine chest CT conditioned scanning quality control model. The original data raw data were used to reconstruct the FOV to be 400 mm×400 mm, 300 mm×300 mm, 200 mm×200 mm and 100 mm×100 mm under the scanning FOV to be 500 mm×500 mm. All other conditions are consistent. Observe the high contrast resolution module of Catphan 500 phantom, and compare the line logarithms of two groups of images under different scanning FOV or different reconstruction FOV. Thirty-five patients with small pulmonary nodules from February 2018 to March 2018 of the Second Affiliated Hospital of Zhejiang University Medical College were retrospectively collected. The raw data were used to reconstruct the images. The FOV was 320 mm×320 mm in the conventional reconstruction group and 100 mm×100 mm in the local magnification reconstruction group. The subjective score data of the two groups were compared by using rank-sum test.@*Results@#When catphan 500 phantom was used, the number of lines in group A and group B increased gradually with the decreasing of FOV. The subjective score of local magnification reconstruction group (4.77±0.35) was higher than that of conventional reconstruction group (3.86±0.50) and the difference was statistically significant (Z=-5.763, P<0.05).@*Conclusion@#Local magnification and reconstruction of high-resolution CT images can achieve the same image quality as local magnification, local magnification and reconstruction of image quality is significantly better than simple image magnification.
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@#AIM: To investigate the effect of inclination and eccentricity of intraocular lens(IOL),on optical imaging quality <i>via</i> wavefront aberration optical path system.<p>METHODS: The spherical IOL Sensar AR40e, the aspherical monofocal IOL Tecnis ZA9003, and the aspheric multifocal IOL Tecnis ZM900 were measured at the center of the center using a laboratory-built Hartmann-Shack IOL wavefront aberration path system at 5.0mm simulated pupil diameter. 0, 0.2, 0.4, 0.6, 0.8mm, the effect on the optical imaging quality when tilting 5°, 10°, 15°, 20°, 25° to the nasal side and the temporal side, and quantitative imaging quality by high-order aberration and modulation transfer function.<p>RESULTS: The Temnis ZA9003 MTF value was higher than AR40e and Tecnis ZM900 when inclinationed within 5°, while the three IOL MTF values were significantly different when inclinationed 5°, 10°, 15°, and 20°. Tecnis ZA9003 The IOL inclination angle was significantly positively correlated with the coma(<i>r</i>=0.842, <i>P</i><0.001), and there was no significant correlation with the spherical aberration(<i>r</i>=0.229, <i>P</i>=0.241). The three IOL MTF values were obtained when the eccentricity was 0.6 and 0.8 mm. Significant differences(both <i>P</i><0.001), the imaging quality of the Tecnis ZM900 eccentricity greater than 0.4mm decreased significantly.<p>CONCLUSION: When the inclination of aspheric IOL(-0.27μm spherical aberration)is less than 5°and the eccentricity is less than 0.4mm, aspherical IOL has a better imaging quality than that of spherical IOL. Tecnis ZM900 IOL has a lower optical imaging quality than that of spherical and aspheric IOL when the eccentricity of IOL is more than 0.4mm.
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Objective To compare the impact of immobilization base plates composed of 7 types of materials on the MR-simulation imaging quality used for radiotherapy,aiming to provide reference data for clinical applications.Methods Using identical T1 and T2 sequences of Siemens MR-simulator,the MR images of ACR Large Phantom were acquired on the Orfit carbon fiber laminate,polycarbonate (PC),high precision base plate (HP),Jinan Huayuxin BR,WR,KP and SP materials,respectively.The imaging quality without any plate was used as the baseline data.The following metrics were compared:1.High-contrast spatial resolution:the sharpness of 3 pairs of hole arrays was observed,which represented resolutions of 1.1 mm,1.0 mm and 0.9 mm on the LR and AP directions;2.Image intensity uniformity in terms of percent integral uniformity (PIU):PIU =100× [1-((high-low)/(high +low)];3.Low-contrast resolution:distinguishable spokes representing resolutions of 5.1％,3.6％,2.5％ and 1.4％ were recorded.According to ACR recommendations,high-contrast resolution of 1.0 mm,PIU of T1WI and T2＞82％and low-contrast spoke difference＜3 were considered as clinically acceptable.Results High-contrast T1WI and T2WI resolutions of no plate,PC plate,HP plate and KP material were all 0.9 mm,and those of the remaining materials were =worse than 0.9 mm.The T1WI and T2WI PIU of no plate was＞87％,and the PIU of carbon fiber plate was reduced by＞ 25％.The PIU decrease of remaining materials was within ±4％.Except the carbon fiber plate,the low-contrast spokes of the remaining materials were within ±3 compared with the reference.Conclusions In clinical settings,carbon fiber plate exerts the most significant effect upon the MR-simulation imaging quality,which is unsuitable for MR simulation.Imaging quality of PC and HP plates are consistent with that of no plate.BR and KP materials exert slight effect upon MR signal.The remaining materials are of potential values for the manufacture of immobilization devices and accessories.
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Objective To study the optical imaging quality of multifocal intraocular lens (IOL) following Nd∶YAG laser damage.Methods Three hydrophobic acrylate discs used to make multifocal IOL were placed in line,and the Nd∶YAG laser was used to emit the posterior surface,mid-plane and anterior surface of the discs by gradually increasing the emitting energy to determine the damaged threshold energy of various planes.Eight multifocal IOLs were divided into 2 groups.IOL damage models were established by emitting 12 points along 12 clocks on circle of 3.0 mm in diameter in the group 1 (IOLs NO.1,2,3,4) and 6 points with 1-clock interval on circle of 1.0 mm in diameter in the group 2 (IOLs NO.5,6,7,8) with Nd∶YAG laser.The modulation transfer function (MTF),line spread function (LSF) and United States air force (USAF) test target images of the IOLs were tested under the optical aperture at 2.0,3.0 and 4.5 mm.Results The damage thresholds of laser power were not significantly different among three hydrophobic acrylate discs (Fgroup =1.100,P =0.337),and the thresholds were significantly different among different planes in the discs (Fposition =195.279,P=0.000),with the highest damage threshold in the anterior surface and the lowest damage threshold in the mid-plane of the discs(all at P＜0.01).The shifts of far focus and near focus MTF curves,LSF curves and USAF target images of the IOLs under the 2.0,3.0 and 4.5 mm optical aperture after laser damage were in coincidence with those before laser damage both in group 1 and group 2.The glare phenomenon of the USAF target image was observed at near focus under the 4.5 mm optical aperture both before and after laser damage.Conclusions Multifocal IOL is vulnerable to injury when the laser beam focuses on the midplane,and the anterior surface of IOL can tolerate certain degree of damage.In standard model eye,the MTF curves,LSF curves and USAF target images of multifocal IOL was not impacted by laser induced spots injuries under different pupil diameters.
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Objective To compare gemstone spectrum imaging (GSI) and auto mA technology for lower extremity arterial CTA to determine whether GSI can decrease radiation dose while increase image quality.Methods Thirty patients were equally divided into a GIS group and an auto mA group.All the patients underwent arterial CTA of both lower limbs.The auto mA group had the noise index (NI) being 15.48 and the current strength range from 20 to 400 mA,and the GSI group applied scanning protocol GSI-36 and 260 mA when used for arterial CTA.The values of CT dose index volumes (CTDIvol) and dose length product (DLP) were recorded,and the effect doses (ED) were calculated.The image quality was evaluated in the two groups,and statistical analysis was carried out.Results GSI and auto mA groups had CTDIvol values being (10.30±40.00) and (9.72±2.86) mGy,DLP values being (1 206.31 ±338.6) and (1 101.4±375.5) mGy· cm,and ED values being (18.10±5.08) and (16.52±5.63) mSv,respectively.The image quality score was (2.87±0.30) in GSI group and (2.57±0.46) in auto mA group,and there were significant difference between the scores (P＜0.05).Conclusion GSI cannot decrease X-ray radiation dose while increase image quality during lower extremity arterial CTA.
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Objective To compare gemstone spectrum imaging (GSI) and auto mA technology for lower extremity arterial CTA to determine whether GSI can decrease radiation dose while increase image quality.Methods Thirty patients were equally divided into a GIS group and an auto mA group.All the patients underwent arterial CTA of both lower limbs.The auto mA group had the noise index (NI) being 15.48 and the current strength range from 20 to 400 mA,and the GSI group applied scanning protocol GSI-36 and 260 mA when used for arterial CTA.The values of CT dose index volumes (CTDIvol) and dose length product (DLP) were recorded,and the effect doses (ED) were calculated.The image quality was evaluated in the two groups,and statistical analysis was carried out.Results GSI and auto mA groups had CTDIvol values being (10.30±40.00) and (9.72±2.86) mGy,DLP values being (1 206.31 ±338.6) and (1 101.4±375.5) mGy· cm,and ED values being (18.10±5.08) and (16.52±5.63) mSv,respectively.The image quality score was (2.87±0.30) in GSI group and (2.57±0.46) in auto mA group,and there were significant difference between the scores (P＜0.05).Conclusion GSI cannot decrease X-ray radiation dose while increase image quality during lower extremity arterial CTA.
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Objective To explore the effects of heart rate changes after holding breath and time for recovering stable heart rate on the quality of coronary CTA.Methods Totally 700 patients undergoing coronary CTA examination in some hospital were enrolled into the study,whose data on initial heart rate at rest condition,maximal heart rate during breath holding,stable heart rate after breath holding as well as the time consumed for recovering stable heart rate were collected and analyzed.Results A heart rate trendgram was drawn to find out the rules for heart rate changes and time for recovering stable heart rate,so that proper retrospective or prospective scanning scheme could be determined.Conclusion Mastering the rules in heart rate changes and time for recovering stable heart rate contributes to guiding coronary CTA.
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Objective To compare image quality and radiation dose of prospective and retrospective electrocardiogram(ECG)-ga-ted 256-slice CT angiography in evaluation of coronary stent.Methods ECG-gated 256-slice CT angiography images of 1 61 cases of coronary heart disease(CHD)patients after stent operation were retrospective analysed,in which patients with stable heart rate were divided into prospective ECG-gated group and restrospective ECG-gated groups.Accooding to normal blood vessels and stent image display,the image quality was divided into four grades:the best,better,good,poor grade,and the quality results were compared. The radiation doses were compared between the two ECG-gated groups.Results In 87 cases (1 58 stents)of prospective ECG gated CT angiography group and 74 cases (159 stents)restrospective ECG-gated CT angiography group the best images were 30 cases (34.5%)and 9 cases (12.2%)(χ2 =10.853,P =0.001),better images 45 cases (5 1.7%)and 41 cases (55.4%)(χ2 =0.218,P =0.641),good ima-ges 12 cases (13.8%)and 21 cases (28.4%)(χ2 =5.22,P =0.022),poor images 0 case and 3 cases(4.0%)(χ2 =1.71 9,P =0.1 90) respectivity.The radiation dose median for prospective ECG-gated angiography group and retrospective ECG-gated angiography group was:5.307 4 mSv,1 7.564 mSv(z = - 10.91 9,P =0.001).The radiation dose of prospective ECG-gated angiography is de-creased by 69.8%.Conclusion For 256-slice CT of coronary stent patient with stable heart rate,image quality of prospective ECG-gated angiography is much better than that of retrospective ECG gated angiography,and the radiation dose of prospective ECG-gated angiography is evident decreased.
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Objective To compare imaging quality and radiation dose on full-field digital mammography (FFDM) system and dual-sided reading CR mammography (DSCRM) system.Methods The TRM of ALVIM statistics phantom was exposed by FFDM system and (DSCRM) with the same radiation dose.The exposure parameters and the entrance surface dose (ESD) were recorded.Then,the phantom was exposed by DSCRM system with different mAs and same kV,and the ESD was recorded.The images obtained above were read by three radiologists on the monitor of diagnosis work station with the same window width and window level.The evaluation of the images were given using a five-level confidence scale.ROC curves were drawn and probability Pdet were calculated.Results The ROC analysis of microcalcifications and masses showed A(z) values of 0.730-0.925 and 0.670-0.945 for FFDM,and 0.632-0.815 and 0.575-0.785 for DSCRM when the radiation dose is 1.36 mGy.The radiation dose with DR system could be reduced compared with dual-sided reading CR system at the same probabilities Pdet,the ESD reduced from 1.63 mGy to 1.36 mGy by 19.8％,the AGD reduced from 0.65 mGy to 0.56 mGy by 16.0％.Conclusions The observable details with FFDM system were proved to be superior to DSCRM system at the same radiation dose.With the similar image quality,the radiation dose of FFDM system was less than the DSCRM system.
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OBJETIVO: O presente experimento visa a validar um protocolo de aquisição em 3D na tomografia por emissão de pósitrons, em substituição ao modo 2D, de forma a reduzir a dose de radiação nos pacientes, sem perda da qualidade de imagens. MATERIAIS E MÉTODOS: Foram realizadas 27 simulações em equipamento Discovery ST, nos modos 2D com quatro minutos de aquisição e 3D com dois e quatro minutos. Utilizou-se um simulador do protocolo da National Electrical Manufacturers Association. No interior deste simulador estão inseridas seis esferas com diferentes diâmetros para a determinação da qualidade de imagem. As aquisições foram comparadas por três médicos nucleares, sem que eles identificassem o modo de aquisição. Cada observador atribuiu o valor igual a 1 quando alguma esfera não foi identificada ou valor 2 para esferas visíveis. RESULTADOS: A análise qualitativa pelo kappa generalizado demonstrou que a frequência de esferasvisíveis foi maior no modo 3D com quatro minutos (85%) e a porcentagem de concordância também foi maior (88,9%), com kappa generalizado = 0,725 [0,507;0,942]. CONCLUSÃO: O modo 3D com quatro minutos de aquisição e com menores atividades de FDG-18F pode ser utilizado em pacientes com biótipo equivalente ao simulador, sem perda de qualidade de imagem.
OBJECTIVE: The present study is aimed at validating a 3D acquisition protocol for positron emission tomography as a replacement for the 2D mode, to reduce the radiation dose delivered to patients, without any loss in the quality of images. MATERIALS AND METHODS: The study comprised 27 simulations in a Discovery ST equipment with four-minute 2D acquisitions, and two-minute and four-minute 3D acquisitions, utilizinga chest phantom according to the National Electrical Manufacturers Association protocol. Six spheres withdifferent diameters were inserted into this phantom as a means for determining the images quality. The images were blindly reviewed by three experienced nuclear physicians who did not know the acquisition modes. Each observer attributed a score 1 when one of the spheres was not identified, or 2 for visible spheres. RESULTS: The qualitative analysis based on generalized kappa coefficient demonstrated that the frequency of visible spheres was higher with four-minute 3D acquisitions (85%), with an also higher interobserver agreement (88.9%), generalized kappa = 0.725 [0.507;0.942]. CONCLUSION: The protocol with four-minute 3D acquisition with lower 18F-FDG activity can be utilized for patients with a biotype similar to the phantom, without any loss in the imaging quality.
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Imaging, Three-Dimensional , Positron-Emission Tomography , Radiation Dosage , Quality Control , Reproducibility of Results , Positron-Emission Tomography/methodsABSTRACT
Objective The imaging quality and irradiation dose were compared between scatter filtering template performance and conventional grid in digital radiography.MethodsImages of contrast-detail phantom and ROC statistic phantom corrected with scatter filtering template method and grid were obtained,respectively.The image quality factors(IQF)and sihnal detection probability values(Pdet)and imaging dose were analyzed by ANOVA,SNK and t test statistics for the two methods of scatter removing.ResultsThe difference of IQF and signal detection probability of images corrected by scatter filtering template technique and conventional snd Was statistically significant.ConclusionsIn digital radiography,STFF can effectively filter scattering,improve image quality without increasing the exposure.With the same image quality.it can reduce the entrance surface dose by about 30% than filter grid.In order to effectively filter scattering,improve the quality of X-ray image,and reduce the patient dose.STFF is an alternative method.
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In this study, we developed the protopype of QA phantom for image QA including an additional component for image based radiation treatment system. The new phantom considered two main parts: Image quality and fusion accuracy. Image quality part included for daily CT number linearity and spatial resolution, and fusion accuracy part designed to simulate a simple translation-rotation setting. The CT scans of the phantom obtained from conventional CT, MVCT of Tomotherapy unit, and both image sets were satisfied the recommendation of spatial resolution. This phantom was simple and efficient for daily imaging QA, and it is important to provide a new concept of verification of image registration.
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Objective To evaluate the image characteristics and quality of MR plain scan with breath-holding in normal lungs. Methods There were 21 normal volunteers to be examined by MR plain scan with breath-holding using T_1WI,T_2WI,PWI fast sequences. It was required to analyze the image characteristics, to measure and calculate signal to noise ratio of the lung parenchyma and the muscle of thoracic wall individually, the contrast and contrast to noise ratio between the lung and the muscle of the thoracic wall. Results On T_1WI,The signal of lung parenchyma was weak and the beating artifacts projected to the lung fields,especially in the left inner and posterior segments. On T_2WI, the lung markings could be seen more, but the noise was obvious in the background and flowing related enhancement appeared in great vessels and heart. On PWI, the signal of lung parenchyma was homogenous and more strong without the beating artifacts of heart and great vessels. According to the order mentioned above, the signal to noise ratio were 1.68?0.21; 2.74?0.26; 4.61?0.79( F =218.06, P