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Objective To explore the correlations between image quality of prospective and retrospective electrocardiogram(ECG)-gated CT coronary angiogram and radiation dose in patients with different heart rates.Methods A total of 135 patients undergoing 256-slice spiral CT coronary angiography were enrolled in the study.Among them,66 cases received prospective ECG-gated scanning(prospective ECG-gated group)and further divided into two subgroups with heart rate≤80 beats/min(prospective ECG-gated+low heart rate subgroup,n=39)and>80 beats/min(prospective ECG-gated+high heart rate subgroup,n=27).The other 69 cases underwent retrospective ECG-gated scanning(retrospective ECG-gated group),including 45 cases with heart rate≤80 beats/min(retrospective ECG-gated+low heart rate subgroup)and 24 with heart rate>80 beats/min(retrospective ECG-gated+high heart rate subgroup).The baseline data,image quality[mean CT value,image noise,signal-to-noise ratio(SNR),subjective image quality score]and radiation dos[CT volume dose index(CTDIvol),dose length product(DLP),effective dose(ED)]were compared among 4 subgroups.The correlations of image quality with heart rate and radiation dose in prospective and retrospective ECG-gated groups were analyzed.Results The heart rates in prospective and retrospective ECG-gated+low heart rate subgroups were lower than those in prospective and retrospective ECG-gated+high heart rate subgroups(P<0.05).When comparing the mean CT value,image noise,SNR and subjective image quality score among 4 subgroups,no statistically significant differences were observed(P>0.05).The CTDIvol,DLP and ED in prospective ECG-gated+low heart rate subgroup were significantly lower than those in the other 3 subgroups(P<0.05),and the indicators in prospective ECG-gated+high heart rate subgroup were lower than those in retrospective ECG-gated group(including low and high heart rate subgroups)(P<0.05).Pearson correlation coefficient analysis revealed that the mean CT value,image noise,SNR,subjective image quality score had no significant correlation with heart rate,CTDIvol,DLP and ED in prospective and retrospective ECG-gated groups(P>0.05).Conclusion The subjective and objective image quality of 256-slice spiral CT coronary angiography is not correlated with radiation dose.Prospective ECG-gated scanning can reduce the radiation dose and ensure the image quality as compared with retrospective ECG-gated scanning.This holds true for eligible patients with high heart rate,and the former can effectively reduce radiation exposure.Therefore,prospective ECG-gated scanning is worthy to be promoted in clinic.
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Purpose To evaluate the image quality improvement of deep learning iterative reconstruction(DLIR)on pediatric head CT images of head injury and to evaluate the performance of DLIR and conventional adaptive statistical iterative reconstruction-veo(ASIR-V)of noise and image texture of CT image in children's head trauma.Materials and Methods A total of 80 cases in Beijing Children's Hospital,Capital Medical University from December 7th to 11th 2020 of children's head low-dose CT were retrospectively selected.Scan voltage was 120 kV.Scan current was 150-220 mA.The raw data were reconstructed into 5 mm thick slice and 0.625 mm thin slice brain window and bone window images.50%ASIR-V and high weight DLIR images(DL-H)were reconstructed,respectively.A 4-point system was used to subjectively evaluate the display of sulcus,brain matter and bone.The number of lesions in each group was counted.The CT value and image noise values of gray matter and white matter were measured,and the contrast to noise ratio was calculated,then measured the blur metric index was measured in the same slice.The differences between the two image reconstruction methods were compared.Results Compared to 50%ASIR-V images,DL-H significantly improved the display ability of the sulcus and ventricles,as well as the display ability of the brain parenchyma(W=5.5-22.2,all P<0.05)in both slice thickness.There was no statistically significant difference in the display ability of the sulcus and ventricles between 5 mm 50%ASIR-V and 0.625 mm DL-H images(W=0.9,2.0,P=0.32,0.05,respectively).In terms of bone display ability,all images could achieve a maximum score of 4.0.A total of 35 lesions were found in 80 patients via 5 mm 50%ASIR-V and DL-H images,including 12 hemorrhagic lesions,1 intracranial gas,9 fractures,and 13 soft tissue swelling.In terms of objective evaluation,the noise level of DL-H images was significantly lower than that of 50%ASIR-V images(t=21.4-35.7,all P<0.05),and there was no statistically significant difference in noise and contrast noise ratio between 5 mm 50%ASIR-V and 0.625 mm DL-H images(t=1.7-2.2,all P≥0.05).The blur metric index showed that DL-H was superior to 50%ASIR-V images(t=6.1,10.0,both P<0.05),and there was no statistically significant difference in blur metric index between 0.625 mm DL-H and 5 mm 50%ASIR-V images(t=2.6,P=0.28).Conclusion DLIR can improve the CT image quality and image texture of children's head trauma,0.625 mm DL-H image quality is close to 5 mm 50%ASIR-V image,which can meet the diagnostic requirements,and possible to further reduce the radiation dose.
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Objective:To study the feasibility and value of applying organ dose modulation technique in computed tomography(CT)scanning on eyes.Methods:A total of 330 patients who admitted to Beijing Friendship Hospital affiliated with Capital Medical University from August 2021 to August 2023 and underwent CT examination on eyes were selected.They were divided into modulation group,conventional group and low-dose group based on the control methods of tube current in scanning.The modulation group used organ dose modulation technique with intelligent automatic tube current of 70-150 mA,and the conventional dose group used a fixed tube current of 100 mA,and the low-dose group used a fixed tube current of 70 mA.The differences in radiation dose and CT imaging quality among 3 groups were compared.Results:The dose length product(DLP),volume CT dose index(CTDIvol)and effective dose(ED)of cross-sectional scan of the modulation group were respectively 62.37,12.83 and 0.143 mSv,which were significantly lower than 115.23,18.93 and 0.265mSv of conventional dose group,respectively,with statistically significant(F=2544.944,6009.596,2544.944,P<0.05).The DLP,CTDIvol and ED of coronary scan of the modulation group were 68.19,13.15 and 0.156,respectively,which were significantly lower than 122.41,19.20 and 0.282 mSv of the conventional dose group,respectively,with statistically significant(F=1232.413,3813.940,1232.413,P<0.05).The excellent rates of cross-sectional scans among the modulation group,conventional group and lower-dose group were respectively 98.83%,86.15%and 47.69%,and the difference among three groups was statistically significant(x2=53.908,P<0.05).The excellent rates of image qualities of the modulation group,conventional group and low-dose group were respectively 96.61%,80.70%and 48.28%,and the difference among three groups was statistically significant(x2=20.992,P<0.05).Conclusion:The application of organ dose modulation technique in CT scanning on eyes can significantly reduce radiation dose on patient under ensures imaging quality can meet diagnostic needs when undergoes cross-sectional and coronal scans,which has higher clinical feasibility and application value.
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Objective:To investigate the effects of different tube voltages combined with artificial intelligence reconstruction algorithm(CI)on the computed tomography(CT)imaging quality and radiation dose of chest phantom on the basis of the CT scan for an adult male simulated chest phantom(PH-N1).Methods:A 512-slice CT scanner of ultrahigh-end was adopted to conduct scan,and the images were divided into 70 kV group,80 kV group,100 kV group and 120 kV group according to different tube voltage.For 4 groups of CT scan images with different tube voltages,the 10%,30%,50%,70%and 90%CI were adopted to reconstruct 1mm thin layer image.The CT volume dose index(CTDIvol)and the dose-length product(DLP)of the scans of 4 groups were compared.The CT values and standard deviation(SD)values of the aorta,abdominal wall fat and erector spine muscle were measured.Two senior diagnostic physicians with more than 5 years of work experience independently and double-blindly evaluated the image quality by using 5-point scale.A Kappa consistency test was conducted.One-way analysis of variance was adopted to compare the differences of CT values and SD values of the tissues of image targets.The Friedman rank-sum test was adopted to compare the differences of subjective image qualities among different groups.Results:The differences of CTDIvol and DLP among 4 groups with different tube voltages were significant(F=1855.617,3996.118,P<0.05),respectively.Under 70 kV tube voltage,there were no significant differences in CT values of the aorta,abdominal wall fat and erector spine muscle,which were reconstructed by using 10%,30%,50%,70%and 90%CI(P>0.05),while the differences of SD values among them were statistically significant(F=32.267,53.327,14.873,P<0.05),respectively.Under the different tube voltages of 4 groups,which were reconstructed by 90%CI,the CT values of aorta,abdominal wall fat and erector spine muscle gradually decreased with decreasing of tube voltage,the differences were significant(F=139.899,2563.93,219.231,P<0.05),respectively.The consistency of subjective scores between two diagnostic physicians was better for each group of images(Kappa=0.712~0.869).Conclusion:Compared with 80 kV,90 kV and 120 kV images,the reconstructed images with 90%CI algorithm under 70 kV tube voltage can significantly reduce the radiation dose,and the images have a favorable signal-to-noise ratio at the same time.
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Objective:To evaluate the feasibility of low radiation dose and low contrast dosage in coronary CT angiography (CCTA) of class I obese patients.Methods:This prospective study enrolled 57 patients (male/female, 50/7, age, 25-77 years) with body mass index (BMI) of 30-38 kg/m 2 and body weight of 85-119 kg scheduled for CCTA from August 2022 to March 2023 in our hospital. The patients were divided into two groups: control group (group A, n = 20) and low-dose group (group B, n = 37). Group A employed a standard-dose protocol: tube voltage 120 kVp and IDR 2.2 g I/s, while group B were scanned using the low-dose protocol: tube voltage 100 kVp and IDR 1.5 g I/s. Images in Group A and Group B were reconstructed with hybrid iterative reconstruction (HIR) at strength 4 and 8, respectively. Other scanning and reconstruction parameters were the same in two groups. Methods:The image quality was assessed by measuring the CT values and noise in the aortic root, left anterior descending artery and right coronary artery, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Subjective image quality was evaluated for vessels according to the 18-segment classification system using a 4-point scale (1. poor, 4. excellent). The effective dose E and contrast dosage were compared. Statistical analysis was performed using independent samples t-test, Mann-Whitney U test or χ 2 test. Results:The BMI of groups A and B were 31.89 (30.77, 33.81) and 31.22 (30.46, 32.83) kg/m 2, respectively ( P>0.05). No statistically significant differences in CT values, noise, SNR, CNR were noticed between the two groups (all P>0.05). The mean subjective score of all coronary artery segments in the two groups were not less than 3, meeting the requirement of clinical diagnosis. There was no statistically significant difference in the overall subjective image quality between the two groups ( P>0.05). The radiation dose E in groups A and B were 7.58 and 4.49 mSv, respectively ( Z=-5.46, P<0.05). The contrast dosage in groups A and B were 66 and 45 ml, respectively. The radiation dose E and contrast dosage in group B were 41% and 32% lower than that in group A, respectively. Conclusions:For class I obese patients, it was feasible to use a low tube voltage (100 kVp) and low IDR (1.5 gI/s) protocol in CCTA. Radiation dose and contrast dosage can be reduced reasonably without compromising the CCTA image quality.
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Objective:To assess the radiation dose and clinical value of "one-stop" whole-brain CT perfusion (CTP) imaging in the evaluation of collateral circulation for patients with acute ischemic stroke (AIS), regarding the digital subtraction angiography (DSA) as the reference.Methods:This retrospective study included 32 AIS patients, for whom both CTP and DSA were obtained <24 h since onset. All CTP scans were acquired in whole-brain volume perfusion mode using a 320-row CT with the phase-specific settings of tube currents to optimize the image quality of CTA images, where multiple-phase (mp) CTA images were extracted from the CTP data in post-processing. The volume CT dose index (CTDI vol), dose length product (DLP), and effective dose were compared to those reported in previous studies. The perfusion parameters of the infarct lesions and their contralateral regions were compared using the paired t-tests. One radiologist scored the collateral circulation with only the CTP and with the CTP plus mp-CTA using a 5-point scale. Another radiologist performed the same evaluation on the DSA. The diagnostic accuracy was calculated referring to the result based on DSA. The scores were analyzed using the Pearson correlation coefficient. The agreement of scores was quantified with the Kappa test. Results:The mean CTDI vol was 184.18 mGy, which was comparable to the result of a previous study (184.19 mGy), and the mean effective dose was reduced 39% compared to that reported in the literature for combined CTP and CTA scanning (6.1 vs 10 mSv). There were statistically significant differences in cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), transit time to peak (TTP), and time-to-maximum (Tmax) between the infarct lesions and their contralateral regions ( P<0.01). The scores between CTP and DSA were significantly correlated ( r=0.95, P<0.01), as well as the scores between CTP plus mp-CTA and DSA ( r=0.98, P<0.01). The Kappa value was 0.64 ( t=7.53, P<0.01) between CTP and DSA, while it increased to 0.88 ( t=9.99, P<0.01) for CTP plus mp-CTA. With the result of DSA as a reference, the diagnostic accuracy was 71.9% and 90.6% for CTP and CTP plus mp-CTA, respectively. Conclusions:The "one-stop" whole-brain CTP imaging with phase-specific settings of tube currents can provide reliable CTP and multiple-phase CTA images simultaneously, which could reasonably reduce the radiation dose. Combined use of multi-phase CTA and CT perfusion improves the diagnostic accuracy of collateral circulation in AIS patients.
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Objective:To explore the differences between the deep learning-based image reconstruction (DLIR) and the adaptive statistical iterative reconstruction V (ASiR-V) algorithms in the radiation dose and image quality of head and neck CT angiography (CTA).Methods:The data of 80 patients undergoing head and neck CTA due to vascular diseases in the head and neck were prospectively collected. These patients were randomly divided into groups A and B based on their examination sequence. The CTA images of group A were reconstructed based on ASiR-V 50%, with a tube voltage of 120 kV and a noise index of 11.0. In contrast, those of group B were reconstructed based on ASiR-V 50% (for group B1) and DLIR-H (for group B2), with a tube voltage of 80 kV and a noise index of 9.0. Then, the radiation doses and image quality of both groups were compared using the independent-sample t-test. The radiation doses, and both subjective and objective image quality of the two imaging method were compared through the Kruskal-Wallis test and the Wilcoxon rank-sum test. The independent- or paired-sample t-test was employed to measure inter-group vascular enhanced CT values, as well as signals and noise from regions of interest (ROIs), with signal-to-noise ratios (SNRs) and contrast-to-noise ratios (CNRs) calculated. Results:The effective doses of groups A and B were (0.77±0.08) and (0.45±0.05) mSv, respectively, with a statistically significant difference ( t = 21.96, P < 0.001). The vascular enhanced CT values, SDs, SNRs, and CNRs in the arch of the aorta, the initial and bifurcation parts of the common carotid artery, and the M1 segment of the middle cerebral artery showed statistically significant differences among groups A, B1, and B2 ( F = 67.69, 68.50, 50.52, 74.10, 63.10, 91.22, 69.16, P < 0.001). Additionally, statistically significant differences were observed in the subjective scores of image quality among groups A, B1, and B2 ( Z = 71.06, P < 0.05). Conclusions:The DLIR algorithm can further reduce the radiation dose in head and neck CTA examination while significantly reducing image noise and ensuring image quality, thus demonstrating high clinical application value.
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Objective:To investigate the clinical value of prospective ECG-gated high-pitch protocol scanning of third generation DSCT in the diagnosis of pediatric congenital heart disease (CHD).Methods:A total of 243 children with confirmed CHD who were expected to undergo surgical treatment were prospectively collected and randomly divided evenly into 3 groups, with first group for prospective ECG-gated high-pitch scanning in third generation DSCT (Flash 3rd), second group for prospective ECG-gated high-pitch scanning in second generation DSCT (Flash 2nd) and third group for prospective sequential scanning in third generation DSCT (Sequence 3rd). The SD value and SNR of aortic root and pulmonary artery of each child were recorded. The 5-point system is adopted with subjective scoring. Based on the result of operation, the diagnosis accuracy in 3 groups was analyzed. Results:The E values in Flash 3rd, Flash 2nd and Sequence 3rd group were 0.24 (0.19, 0.27), 0.11 (0.10, 0.14) and 0.44 (0.39, 0.48) mSv ( H=207.04, P<0.05), respectively. Subjective scores of group Flash 3rd and Sequence 3rd were significantly higher than that of group Flash 2nd [4 (4, 4) vs. 4(3, 4) vs. 3(3, 3), H=124.05, P<0.05] and no difference between these two groups. SD value of aortic root and pulmonary artery of group Flash 3rd and Sequence 3rd were significantly lower than that of group Flash 2nd( H= -40.27-33.38, P<0.05). SNR of aortic root and pulmonary artery of group Flash 3rd was significantly higher than that of group Flash 2nd and Sequence 3rd ( H=-0.90-51.42, P<0.05). Diagnosis accuracy of intracardiac malformation for group Flash 2nd was significantly lower than that of Flash 3rd and Sequence 3rd (77.7%, 90.9%, 88.9%, K=9.36, P<0.05), and there was no significant difference between the latter two groups. There was no difference in diagnosis accuracy of extracardiac malformation among 3 groups (88.6%, 94.8%, 92.2%, K=3.11, P=0.21). Conclusions:The prospective ECG-gated high-pitch scanning in third generation DSCT can take into account radiation dose and image quality, which has important clinical value in the diagnosis of CHD.
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Objective To investigate the present situation of radiation environment in Beijing and provide data support for monitoring and management of radiation environment in Beijing. Methods The γ radiation dose rate of environmental surface as well as the radioactive levels of aerosol, sediment, surface water, and soil samples were monitored in Beijing from 2015 to 2022. The radioactive levels of various environmental elements in this area were presented using statistical charts and statistical tables, and the related issues were discussed. Results The automatic monitoring and cumulative monitoring results of γ radiation dose rate were in the range of local natural background fluctuation. The radioactive levels of beryllium-7, lead-210, and polonium-210 in aerosols were low in summer and high in winter. The radioactive levels of total α, total β, and beryllium-7 in sediments were low in winter and high in summer. The activity concentration of radionuclide potassium-40 in aerosols and sediments did not change significantly with seasons. The total α and total β radioactivity levels of surface water fluctuated within the range of background. These values of reservoir water were within the limits specified in the Hygienic Standard for Drinking Water (GB 5749—2006). Natural radionuclides in soil were within the range of natural background fluctuation, and artificial radionuclides in soil were within the range of normal fluctuation over the years. Conclusion From 2015 to 2022, the environmental surface γ radiation dose rate as well as aerosol, sediment, surface water, and soil radioactivity levels in Beijing were generally low, all of which fluctuated within the environmental background.
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Computed tomography (CT) examination may expose patients to a high radiation dose. The reduction of radiation dose in pediatric CT examinations is becoming increasingly important. The diagnostic reference level (DRL) is a practical tool that can achieve optimization of protection and reduce radiation dose in pediatric CT examinations. This article provides a brief summary of the concept, development methods, current situations by country, and issues related to the DRL in pediatric CT examinations, aiming to provide a references for radiation protection optimization in pediatric CT examinations in China.
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Objective To investigate the feasibility of low-voltage,automatic tube current adjustment(ATCM)and low contrast agent concentration,dose and injection rate combined with full-model iterative re-construction(IMR)in vertebral artery V3-segment three-dimensional CT angiography(3DCTA).Methods A total of 60 patients with suspected upper cervical spine,craniocervical junction lesions undergoing cervical vertebral artery V3 segment 3DCTA in this hospital from November 2019 to May 2020 were selected and divided into the group A and B by adopting the random number table method,30 cases in each group.The group A adopted the ATCM technology of 80 kV,average tube current of 50 mAs,25 mL of contrast agent io-hexol(iodine content 300 mg/mL)combined IMR technology with an injection rate of 3 mL/s,while the group B adopted 120 kV,150 mAs fixed tube current,50 mL injection rate of 5 mL/s contrast agent iopamidol(iodine content 370 mg/mL)combined filter back projection(FBP)reconstruction technology.CT value,noise,signal-to-noise ratio(SNR),contrast noise ratio(CNR)and image sensitivity(FOM)were measured and compared between the two groups and the quality of the resulting images was evaluated.The CT volumet-ric dose index(CTDIvol)and dose-length product(DLP)were recorded,and the effective dose(ED)was cal-culated.Results There was no statistically significant difference in the vertebral arterial CT value between the two groups(P>0.05),but the noise of the group A was lower than that of the group B(P<0.05),SNR,CNR and FOM of the group A were greater than those of the group B(P<0.05).The image quality of the two groups met the requirements of clinical diagnosis[(4.78±0.41)points vs.(4.85±0.35)points],and there was no statistically significant difference in the subjective evaluation of image quality(P>0.05).The CTDIvol,DLP and ED levels in the group A were lower than those in the group B(P<0.05).The iodine in-takes of contrast medium in the group A and group B were 7.5 g and 18.5 g,respectively,and the iodine flow rates of contrast agent were 0.9 and 1.85 mg/s,respectively,and compared with group B,the iodine intake and iodine flow rate of the group A were decreased by 59.5%and 51.4%,respectively.Conclusion Low tube voltage ATCM and low contrast concentration,dose and injection rate combined with IMR technology can not only ensure the 3DCTA image quality of vertebral artery V3 segment,but also reduce the radiation dose re-ceived by the patients,and reduce the iodine intake and iodine flow rate of contrast agent.
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Objetivos: el objetivo de este trabajo fue integrar curvas de densidad electrónica relativa al sistema de planificación de tratamiento CAT3D utilizando el método alternativo de la calibración estequiométrica. Métodos: se utilizó aluminio como material de calibración y un maniquí torácico con insertos y se consideraron 3 casos en la planificación del tratamiento: campo directo 10x10cm2, campo directo 20x20cm2 y campo lateral 10x10cm2 con cuña, donde se puso a prueba el sistema de planificación basado en el algoritmo Pencil Beam. Resultados: se encontró que el uso incorrecto de estas curvas afecta significativamente la dosis absorbida hasta en un 6% en regiones de cambios bruscos de densidad, excediendo la tolerancia recomendada de ±5% en la entrega de dosis adsorbida en regiones de equilibrio electrónico. Conclusiones: se concluyó que la implementación y uso correcto de estas curvas mejora la aproximación en medios heterogéneos, reduciendo la desviación de sus resultados.
Objectives: the objective of this work was to integrate relative electron density curves to the CAT3D treatment planning system using the alternative method of stoichiometric calibration. Methods: aluminum was usec as calibration material and a thoracic mannequin with inserts and 3 cases were considered in the treatment planning: direct field 10x10cm2, direct field 20x20cm2 and lateral field 10x10cm2 with wedge, where the planning system based on the Pencil Beam algorithm was tested. Results: it was found that incorrect use of these curves significantly affects the absorbed dose by up to 6% in regions of sudden changes in density exceeding the recommended tolerance of ±5% in the delivery of adsorbed dose in regions of electronic equilibrium. Conclusions: it was concluded that the implementation and correct use of these curves improves the approximation in heterogeneous media, reducing the deviation of their results.
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Abstract Objectives: To determine the cut-off point of the cochlear radiation dose as a risk factor for hearing loss in patients with vestibular schwannoma treated with radiosurgery. Methods: A systematic review of the literature was performed without language or publication year restrictions in the MEDLINE/PubMed, EMBASE, Web of Science, LILACS/VHL and Cochrane Library databases. Studies that met the following criteria were included: 1) population: adults of both sexes who underwent radiosurgery for vestibular schwannoma treatment; 2) exposure: cochlear radiation; 3) outcome: hearing loss; 4) type of study: cohort. Two independent reviewers conducted the entire review process. The registration number in PROSPERO was CRD42020206128. Results: From the 333 articles identified in the searches, seven were included after applying the eligibility criteria. There was no standardization as to how to measure exposure or outcome in the included studies, and most studies did not present sufficient data to enable meta-analysis. Conclusion: It was not possible to determine a cut-off point for high cochlear dose that could be considered a risk factor for hearing loss.
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RESUMEN Los Niveles de Referencia para Diagnóstico (NRD) son una herramienta dinámica que gana cada vez una mayor importancia para la optimización de las exposiciones médicas. La disponibilidad de información científica es esencial en este proceso de optimización para Medicina Nuclear (MN) y Radiología Diagnóstica (RD). Este trabajo presenta un estudio de la disponibilidad de información sobre los NRD para MN y RD en la base PubMed, en los últimos 20 años, empleando diferentes palabras clave. Se analizó de forma crítica la información disponible, buscando los cambios principales que se han producido como tendencia en diferentes aspectos del establecimiento de los NRD. Se verificó un desbalance significativo en la disponibilidad de literatura científica en estas dos áreas, aunque se ha incrementado la información para equipos híbridos y de forma general para todas las tecnologías. Este desbalance se hace mayor para estudios de medicina nuclear en pediatría. Se observaron avances en la forma de recolectar datos, la manera de organizar la información y analizarla, en especial con la disponibilidad de sistemas de monitoreo de dosis. Se encontró que, en los estudios TC e intervencionismo, las agrupaciones por localización anatómica están siendo acotadas o restringidas, por indicaciones clínicas que tienen similitudes en los requisitos de calidad de imagen para el diagnóstico adecuado. Similarmente en MN se vislumbra la incorporación de la actividad por peso como NRD en las tecnologías híbridas y estudios pediátricos. Este estudio demuestra que, en general, la literatura científica disponible sobre los NRD es mucho más amplia para pacientes adultos. Se requiere más estudios pediátricos, especialmente en el área de MN
ABSTRACT Diagnostic Reference Levels (DRLs) are a dynamic tool that is gaining more and more importance for the optimization of medical exposures. The availability of scientific information is essential in this optimization process for Nuclear Medicine (NM) and Diagnostic Radiology (DR). This work presents a revision of the information's availability about DRL in the PubMed database, in the last 20 years, using different search combinations. The available information was critically analyzed, looking for the main changes that have occurred as a trend in different aspects of the establishment of the NRD. A significant disparity in the amount of information between the two areas on the subject was verified, although there has been an increase of available scientific papers for hybrid equipment, and in general for all technologies. The disparity becomes greater for NM studies in pediatrics population. The way to collect data, the mode to organize the information and analyze it, has also undergone changes, mainly with radiation dose management systems. In CT and interventional studies, the grouping by anatomical locations is being constrained or modulated by clinical indications with analogous image quality requirements for proper diagnosis. Something similar happens in MN, where the incorporation of activity/patient's weight is envisioned as NRD for hybrid technologies and pediatric studies. In general, the study showed that, the scientific paper's availability about DRL for adult population are much wider. More pediatric studies on these subjects are needed, especially in NM
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Humans , Radiation Dosage , Diagnostic Reference Levels , Nuclear MedicineABSTRACT
ABSTRACT BACKGROUND: Computer-aided diagnosis in low-dose (≤ 3 mSv) computed tomography (CT) is a potential screening tool for lung nodules, with quality interpretation and less inter-observer variability among readers. Therefore, we aimed to determine the screening potential of CT using a radiation dose that does not exceed 2 mSv. OBJECTIVE: We aimed to compare the diagnostic parameters of low-dose (< 2 mSv) CT interpretation results using a computer-aided diagnosis system for lung cancer screening with those of a conventional reading system used by radiologists. DESIGN AND SETTING: We conducted a comparative study of chest CT images for lung cancer screening at three private institutions. METHODS: A database of low-dose (< 2 mSv) chest CT images of patients at risk of lung cancer was viewed with the conventional reading system (301 patients and 226 nodules) or computer-aided diagnosis system without any subsequent radiologist review (944 patients and 1,048 nodules). RESULTS: The numbers of detected and solid nodules per patient (both P < 0.0001) were higher using the computer-aided diagnosis system than those using the conventional reading system. The nodule size was reported as the maximum size in any plane in the computer-aided diagnosis system. Higher numbers of patients (102 [11%] versus 20 [7%], P = 0.0345) and nodules (154 [15%] versus 17 [8%], P = 0.0035) were diagnosed with cancer using the computer-aided diagnosis system. CONCLUSIONS: The computer-aided diagnosis system facilitates the diagnosis of cancerous nodules, especially solid nodules, in low-dose (< 2 mSv) CT among patients at risk for lung cancer.
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Objective:To investigate the effect of off-center positioning on image quality and radiation dose when automatic tube current modulation(ATCM)technique is used in computed tomography(CT)scanning on chest.Methods:A GE Revolution 256-row spiral CT machine was used to perform CT scan on a simulation phantom of chest by adopting ATCM technique,and the off-center situation was simulated by adjusting the height of the examination bed.The posterior-anterior localization image scanning method was adopted to enroll the posterior-anterior localization image group,and the dual-localization image scanned the dual-localization image group,and both groups were centered as the mid-axillary line of the body.The different positions of phantom in scan field were simulated through adjusted the height of the examination bed.The phantom of each group was scanned at 80 mm,60 mm,40 mm,20 mm,0 mm,-20 mm,-40 mm,-60 mm and-80 mm of the mid-axillary line.Both groups were scanned under the same scanning parameters,and the volume CT dose index(CTDIvol)and dose-length-product(DLP)were recorded for each group.The objective noise(SD)of the imageries of two groups were measured and compared,and two attending physicians with 5 years of work experiences of radiology department adopted respectively dual blind method to conduct subjective scoring for ground glass nodules(GGN),and the mean of scores was used to evaluate the results.Results:The CTDIvol value of the posterior-anterior localization image group was 4.56 when the off-center was-80 mm of the mid-axillary line,which increased 54.05%than that when the off-center was 0 mm.The CTDIvol value was 2.12 when the off-center was 80 mm,which decreased 28.38%than 0 mm of off-center.The CTDIvol value was 3.20 when the dual-localization image group was located at-80 mm of off-center,which decreased 3.61%than 0 mm of off-center.The CTDIvol value was 3.31 when the off-center was 80mm,which decreased 0.30%than that when off-center was 0mm.There was no statistically significant difference in subjective GGN scores between the two groups at different positions of off-center.Conclusion:Off-center positioning scan has greater effect on radiation dose when using posterior-anterior localization image scans,while the off-center positioning scan does not have effect on radiation dose when using dual localization image scan.The dual localization image should be adopted to perform CT scan on chest when the lateral center of the thorax cannot be determined in clinical practice,which can reduce the radiation dose of patients.
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Objective:To explore the effectiveness of deep learning image reconstruction (DLIR) algorithm compared to adaptive statistical iterative reconstruction (ASIR-V) algorithm in improving the quality of low-dose brain CT images.Methods:Retrospective inclusion of patients who underwent brain CT examination in the People's Liberation Army General Hospital from November 2021 to August 2022. Four different algorithms were used to reconstruct low-dose CT scans of all patients to obtain 30% intensity ASIR-V (ASIR-V-30%) images, low intensity DLIR (DLIR-L) images, medium intensity DLIR (DLIR-M) images, and high intensity DLIR (DLIR-H) images. The regions of interest were selected from four sets of images, including superficial white matter, superficial gray matter, deep white matter, and deep gray matter, and their CT values and standard deviations were measured for calculating signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR).Subjective evaluation of image quality was conducted by three neuroimaging physicians based on the Likert 5-component scale. The objective and subjective scores of the 4 groups of images were analyzed using ANOVA or Kruskal Wallis. If there are overall differences, pairwise comparisons were conducted within the group.Results:A total of 109 patients were enrolled, including 104 males and 5 females, aged 65-110 years (89.16 ± 9.53) years. The radiation exposure of brain CT low-dose scanning was (0.93 ± 0.01)mSv, significantly lower than that of conventional scanning (2.92 ± 0.01) mSv ( t = 56.15, P < 0.05). The differences in objective image quality analysis of ASIR-V-30%, DLIR-L, DLIR-M, and DLIR-H images of low-dose CT in SNR deep gray matter, SNR deep white matter, SNR superficial gray matter, SNR superficial white matter, CNR deep gray white matter, and CNR superficial gray white matter were statistically significant( F =98.23, 72.95, 68.43, 58.24, 241.13, 289.91, P < 0.05). Among them, DLIR-H images had the lowest noise in deep gray matter, deep white matter, superficial gray matter, and superficial white matter, and had statistically significant differences compared to other image groups ( t = 167.43, 275.46, 182.32, 361.54, P < 0.05). The subjective score of DLIR-H image quality was superior to ASIR-V-30%, DLIR-L, and DLIR-M, with the statistically significant difference ( t = 7.25, 8.32, 9.63, P < 0.05). Conclusions:Compared with ASIR-V, DLIR algorithm can effectively reduce image noise and artifacts in low-dose brain CT, and improve SNR and CNR. The subjective and objective image quality evaluation of DLIR-H is the best.
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Objective:To evaluate the feasibility of coronary artery calcium (CAC) detection, quantification and risk classification using ultra-low-dose chest CT (ULD-CT) combined with a calcium-aware algorithm.Methods:A total of 115 patients were prospectively enrolled from April to October 2022 at Zhejiang Provincial People′s Hospital, who underwent a standard calcium scoring CT (CACS-CT) scan followed by an additional ULD-CT scan. CACS-CT adopted a prospective ECG-triggered sequence scan with a tube voltage of 120 kVp, and the reconstruction algorithm with Qr36 (group CACS-CT Qr). ULD-CT adopted non-ECG-triggered high-pitch scan with a tube voltage of Sn 100 kVp, and the standard algorithm Qr36 (group ULD-CT Qr) and calcium-aware algorithm Sa36 (group ULD-CT Sa) were respectively used to reconstruct two groups of images. Taking the CAC detection of CACS-CT as a reference, the accuracy of ULD-CT for detecting CAC was calculated, and kappa was used to evaluate the agreement of CAC detection between scanning protocols. The agreement of CACS quantification between scanning protocols was assessed using intraclass correlation coefficients (ICC) and Bland-Altman plots, and the agreement of risk classification between scanning protocols was assessed using weighted kappa. Results:The CAC was found in 66.96% (77/115) of patients in CACS-CT Qr. Taking the CAC detection in CACS-CT Qr as a reference, the sensitivity of CAC detection in ULD-CT Qr and ULD-CT Sa was 96.1% and 97.4%, respectively, and the specificity was 94.73% (k= 0.902, 0.921). The CACS for ULD-CT Qr and ULD-CT Sa was lower than that for CACS-CT Qr (3.6, 6.2 vs. 8.5; P< 0.001), but strongly correlated with CACS for CACS-CT Qr ( r= 0.983, P< 0.001). The mean difference in CACS for ULD-CT Sa and CACS-CT Qr was smaller (12.33), and the agreement was better (ICC= 0.992). The agreement of risk classifications between ULD-CT Sa and CACS-CT Qr was relatively high (weighted k= 0.936), and the reclassification rate (6.08%) was relatively low. The effective radiation dose for ULD-CT was reduced by approximately 77.22% compared with that for CACS-CT. Conclusions:It is feasible to evaluate CACS using Non-ECG-triggered ULD-CT combined with a calcium-aware algorithm.
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Objective:To study the level of CT dose to paediatric patients in Tianjin, and to provide basic data for establishing the diagnostic reference levels for paediatric patients from CT examinations in Tianjin.Methods:In 2022, a general survey was carried out of the CT doses to the head, chest, abdomen and pelvis of the scanned paediatric patients in two tertiary pediatric hospitals and seven tertiary general hospitals in Tianjin. The scanned pediatric patients were divided into four age groups in terms of the age of -1, -5, -10 and -15 years, and 20 patients were investigated in each age group in each hospital. The basic information were collected on the scanned patients, CT scanning parameters, volume CT dose index (CTDI vol), dose length product (DLP), and the differences in CTDI vol and DLP on the same site among different age groups and different types of hospitals were analyzed. Results:There were significant differences in CTDI vol and DLP between different age groups at the same site (head, chest, abdominal and pelvic, CTDI vol:χ2=296.51, 193.82, 291.72, P<0.001; DLP: χ2=291.22, 263.63, 344.97, P<0.001). There were significant differences in CTDI vol and DLP among different types of hospitals on the same site (head, chest, abdominal and pelvic, CTDI vol:Z=-13.13, -7.57, -15.27, P<0.001; DLP: Z=-9.07, -6.15, -11.57, P < 0.001). Conclusions:The 75 th percentile values of CTDI vol and DLP for pediatric head, chest, abdomen and pelvis CT scanning in tertiary hospitals in Tianjin are at a good level, and the dose on some examination sites are relatively high. Further optimization of pediatric CT scanning procedures is necessary.
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Objective:To compare the efficacy and safety of high- and standard-dose radiotherapy (HD-RT vs. SD-RT) during definitive concurrent chemoradiotherapy (dCCRT) for esophageal cancer (EC), aiming to assess the advantages and disadvantages of these two radiotherapy doses when using modern radiotherapy techniques. Methods:Literature review was conducted from PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang database, and abstracts of the American Society of Radiation Oncology (ASTRO) and the European Society of Radiotherapy and Oncology (ESTRO). Randomized controlled trials (RCT) comparing high-dose radiotherapy (HD-RT: ≥59.4 Gy,1.8 Gy per time) with standard-dose radiotherapy (SD-RT: 50 Gy, 2 Gy per time, or 50.4 Gy, 1.8 Gy per time) during dCCRT for EC were included. The retrieval time was from the establishment of the database to January 1, 2023. The meta-analysis was performed using Stata 16.0 software.Results:A total of 1 158 patients from 5 RCT that meet the inclusion criteria were finally included. In 4 RCT, subgroup analysis of 940 patients using modern radiotherapy techniques were performed. Patients in the HD-RT and SD-RT groups had similar 1-, 2-, and 3-year overall survival (OS)( RR=1.03, 95% CI=0.86-1.22, P=0.757; RR=1.05, 95% CI=0.94-1.17, P=0.433; RR=1.05, 95% CI=0.96-1.14, P=0.314; respectively) and 2- and 3-year locoregional progression-free survival (LRPFS) ( RR=0.94, 95% CI=0.82-1.08, P=0.390; RR=0.96, 95% CI=0.86-1.09, P=0.560; respectively). Patients in the HD-RT group had a higher incidence of grade ≥ 3 treatment-related adverse reactions rates ( OR=1.35, 95% CI=1.03-1.77, P=0.029) and treatment-related death rates ( OR=1.66, 95% CI=0.97-2.83, P=0.062) compared with their counterparts in the SD-RT group. In the subgroup analysis using modern radiotherapy techniques, HD-RT did not improve LRPFS compared to SD-RT, but increased the incidence of adverse reactions, and yielded no OS benefit. Conclusions:Whether modern precision radiation therapy is employed or not, SD-RT yields similar LRPFS and OS, and lower grade ≥ 3 treatment-related adverse reactions rates compared with HD-RT. Therefore, standard-dose (50 Gy, 2 Gy per time, or 50.4 Gy, 1.8 Gy per time) should be considered as the recommended dose in dCCRT for EC. Further RCT are needed to verify our conclusions.