Research progress on the diagnostic reference level for CT examination in children / 中国辐射卫生

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.

Feasibility study of low tube voltage and low contrast medium combined with IMR technology in 3DCTA of vertebral artery V3 segment / 重庆医学

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.

Correlations between image quality and radiation dose in prospective and retrospective ECG-gated CT coronary angiography in patients with different heart rates / 中国医学物理学杂志

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.

Feasibility of Deep Learning Algorithm to Optimize the Noise and Texture of Children's Head CT / 中国医学影像学杂志

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.

Study on the feasibility of the application of organ dose modulation technique of CT scanning for the eye / 中国医学装备

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.

Study on the effects of AI reconstruction algorithm based on different tube voltages on CT imaging quality and radiation dose of chest phantom / 中国医学装备

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.

Feasibility of low radiation dose and low contrast dose for coronary CT angiography in obese patients / 中华放射医学与防护杂志

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.

Radiation dose and clinical value of whole-brain CT perfusion imaging in the assessment of collateral circulation / 中华放射医学与防护杂志

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.

Application value of the deep learning-based image reconstruction algorithm in combined head and neck CT angiography with low radiation dose / 中华放射医学与防护杂志

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.

Clinical value of prospective ECG-gated high-pitch CT scanning in the diagnosis of pediatric congenital heart disease / 中华放射医学与防护杂志

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.

Monitoring and evaluation of environmental radioactivity levels in Beijing, China, 2015—2022 / 中国辐射卫生

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.

Implementación de las curvas de densidad electrónica relativa al sistema de planificación de tratamiento en teleterapia mediante la calibración estequiométrica

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.

Cochlear radiation dose and hearing loss in patients with vestibular schwannoma undergoing radiosurgery: systematic review

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.

Niveles de referencia para diagnóstico según PUBMED: ¿es suficiente la información disponible? / Diagnostic reference levels according to PUBMED: is the information available sufficient?

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

Computer-aided diagnosis system versus conventional reading system in low-dose (< 2 mSv) computed tomography: comparative study for patients at risk of lung cancer

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.

Investigation and analysis of radiation doses to CT examinees in 11 medical institutions in Shijiazhuang, China / 中国辐射卫生

Objective To investigate radiation doses to examinees undergoing computed tomography (CT) scanning of different body parts (the head, chest, and abdomen) in medical institutions of Shijiazhuang, China, and to provide a reference for optimizing radiation protection for examinees in medical institutions. Methods March 2021 to March 2022, eleven medical institutions of radiation monitoring in Shijiazhuang were surveyed for the basic information, scanning parameters, and dosimetric data of a total of 930 adults and children who received CT examinations. The dosimetric data of the subjects were analyzed and compared with the domestic and international diagnostic reference levels and the results of other cities in China. Results In the above hospitals, the CTDIvol(P50) of CT subjects in children's group were 17.42-50.45 mGy, 2.13-14.01 mGy and 3.58-28.20 mGy, respectively. DLP(P50) ranges from 228.87 to 966.97 mGy·cm, 33.20 to 296.03 mGy·cm, and 74.90 to 926.53 mGy·cm, respectively. In the adult group, the CTDIvol(P50) in the head, chest and abdomen of CT subjects were 37.28-54.05 mGy, 6.43-14.99 mGy and 8.28-18.75 mGy, respectively. DLP(P50) ranges from 372.81 to 630.56 mGy·cm, from 219.77 to 467.93 mGy·cm, and from 313.86 to 689.87 mGy·cm, respectively. The distribution of radiation doses in different-grade hospitals varied greatly. The abdomen dose of the children's hospital was higher than other hospitals. Especially the primary hospitals were significantly higher than the recommended diagnostic reference level (DRL). Conclusion In some secondary and primary hospitals, the setting of CT scanning parameters was simplified, not specific to the subjects’ age and body types. They should strictly comply with the principal of optimizing radiation protection to strengthen radiation dose optimization and supervision, reducing the radiation dose of examinees in future examinations .

Research Progress in Diagnostic Reference Levels in Interventional Radiology / 中国医学科学院学报

During interventional procedures,subjects are exposed to direct and scattered X-rays.Establishing diagnostic reference levels is an ideal way to optimize the radiation dose and reduce radiation hazard.In recent years,diagnostic reference levels in interventional radiology have been established in different countries.However,because of the too many indicators for characterizing the radiation dose,the indicators used to establish diagnostic reference levels vary in different countries.The research achievements in this field remain to be reviewed.We carried out a retrospective analysis of the definition,establishment method,application,and main factors influencing the dose difference of the diagnostic reference level,aiming to provide a basis for establishing the diagnostic reference level for interventional procedures in China.

Analysis of risk factors of radiation-induced toxicity in limited-stage small cell lung cancer treated with hypofractionated intensity-modulated radiotherapy / 中华肿瘤杂志

Objective: To compare the incidence of radiation-related toxicities between conventional and hypofractionated intensity-modulated radiation therapy (IMRT) for limited-stage small cell lung cancer (SCLC), and to explore the risk factors of hypofractionated radiotherapy-induced toxicities. Methods: Data were retrospectively collected from consecutive limited-stage SCLC patients treated with definitive concurrent chemoradiotherapy in Cancer Hospital of Chinese Academy of Medical Sciences from March 2016 to April 2022. The enrolled patients were divided into two groups according to radiation fractionated regimens. Common Terminology Criteria for Adverse Events (CTCAE, version 5.0) was used to evaluate the grade of radiation esophagus injuries and lung injuries. Logistic regression analyses were used to identify factors associated with radiation-related toxicities in the hypofractionated radiotherapy group. Results: Among 211 enrolled patients, 108 cases underwent conventional IMRT and 103 patients received hypofractionated IMRT. The cumulative incidences of acute esophagitis grade ≥2 [38.9% (42/108) vs 35.0% (36/103), P=0.895] and grade ≥ 3 [1.9% (2/108) vs 5.8% (6/103), P=0.132] were similar between conventional and hypofractionated IMRT group. Late esophagus injuries grade ≥2 occurred in one patient in either group. No differences in the cumulative incidence of acute pneumonitis grade ≥2[12.0% (13/108) vs 5.8% (6/103), P=0.172] and late lung injuries grade ≥2[5.6% (6/108) vs 10.7% (11/103), P=0.277] were observed. There was no grade ≥3 lung injuries occurred in either group. Using multiple regression analysis, mean esophageal dose ≥13 Gy (OR=3.33, 95% CI: 1.23-9.01, P=0.018) and the overlapping volume between planning target volume (PTV) and esophageal ≥8 cm(3)(OR=3.99, 95% CI: 1.24-12.79, P=0.020) were identified as the independent risk factors associated with acute esophagitis grade ≥2 in the hypofractionated radiotherapy group. Acute pneumonitis grade ≥2 was correlated with presence of chronic obstructive pulmonary disease (COPD, P=0.025). Late lung injuries grade ≥2 was correlated with tumor location(P=0.036). Conclusions: Hypofractionated IMRT are tolerated with manageable toxicities for limited-stage SCLC patients treated with IMRT. Mean esophageal dose and the overlapping volume between PTV and esophageal are independently predictive factors of acute esophagitis grade ≥2, and COPD and tumor location are valuable factors of lung injuries for limited-stage SCLC patients receiving hyofractionated radiotherapy. Prospective studies are needed to confirm these results.

Analysis of radiation dose and influencing factors during interventional procedures for 94 patients with pediatric congenital heart disease / 中国辐射卫生

Objective To evaluate the radiation dose of interventional procedure for children with congenital heart disease, and to analyze the differences in radiation dose and influencing factors. Methods A total of 94 children who underwent interventional procedure for congenital heart disease at a grade A tertiary hospital in Jinan, Shandong Province, China from June 2021 to September 2022 were included in this study. The patients were divided into three groups according to the type of procedure: ventricular septal defect occlusion group (VSD, 48 cases), patent ductus arteriosus occlusion group (PDA, 29 cases), and atrial septal defect occlusion group (ASD, 17 cases). The basic information of patients and postoperative dose reports were recorded. A statistical analysis was performed using SPSS software. Results The median cumulative air kerma (CAK) of VSD, PDA, and ASD was 100.5, 43.7, and 12.1 mGy, respectively. The median air kerma area product (KAP) of VSD, PDA, and ASD was 3.309, 1.313, and 0.540 Gy·cm2, respectively. The median KAP·kg−1 of VSD, PDA, and ASD was 0.179, 0.088, and 0.031 Gy·cm2·kg−1, respectively. There were significant differences in fluoroscopy time, number of cine images, CAK, KAP, and KAP·kg−1 among the three types of interventional procedures (P<0.05). Compared with PDA and ASD, VSD showed significantly higher fluoroscopy time, number of cine images, CAK, KAP, and KAP·kg−1 (P<0.05). Multiple linear regression analysis found that age (B=52.445, P<0.05), weight (B=13.077, P<0.05), fluoroscopy time (B=0.425, P<0.05), tube current (B=0.872, P<0.05), and number of cine images (B=0.660, P<0.05) were positively correlated with KAP, while there was no significant association between height and KAP (P>0.05). Conclusion There are differences in radiation dose among the three types of procedures. Reducing fluoroscopy time, tube current, and number of cine images while meeting the procedure requirements is of great significance for reducing the radiation dose received by children.

A modal study of the effect of adjusting density exposure steps on image quality and radiation dose in digital mammography / 中华放射学杂志

Objective:To investigate the effect of adjusting density exposure steps on image quality and radiation dose in digital mammography.Methods:Using the automatic exposure control (AEC) mode of the digital mammography machine, five different gland thicknesses of 4.3, 5.3, 6.3, 7.3, and 8.3 cm were simulated by attaching 0, 1, 2, 3, and 4 PMMA plexiglass plates under the RMI-156 modal body, and the density exposure steps were adjusted to -3, -2, -1, 0, 1, 2, 3, and 4 for each thickness. The target/filter combination, tube voltage, tube current, incident body surface dose (ESD), incident surface air kerma (ESAK), half-value layer (HVL) and the average glandular dose displayed by the device (displayed AGD) were recorded at each step and thickness, and the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), figure of merit (FOM) and the calculated average glandular dose (calculated AGD) were calculated. Then, the display effects of simulated fibers, simulated calcifications and simulated masses within the modal body were scored subjectively, and the changes in image quality and radiation dose at different steps were analyzed, and the relationships between ESD and ESAK, displayed AGD and calculated AGD, and displayed AGD/ESD and calculated AGD/ESAK were analyzed. A linear fit was used for the steps with SNR, CNR, and FOM, and an exponential function curve fit was used for the steps with mAs, ESAK, and calculated AGD. The differences between ESD and ESAK, displayed AGD and calculated AGD, and displayed AGD/ESD and calculated AGD/ESAK were analyzed by paired-samples t test. Results:The CNR and SNR of mammographic images rose and fell by about 8% with each increase or decrease of one step. The scores of image simulated fibers, simulated calcifications, and simulated masses showed an overall upward trend with increasing steps, but there were still cases where the scores decreased with increasing grades. FOM varied from 97% to 104% at each grade with little variability. ESD, ESAK, displayed AGD, and calculated AGD, which could measure radiation dose, showed an exponential trend of increasing function with increasing steps, with a variation of about 63% to 165%. There were statistically significant differences ( t=-9.61, P=0.001) between ESD (15.14±10.08) and ESAK (16.66±11.07). However, there were no statistically significant differences ( t=1.20, P=0.240) between displayed AGD and calculated AGD, which were 3.66±2.18 and 3.61±1.99, respectively. Conclusions:The adjustment of density exposure steps can make the image quality change linearly and the radiation dose change exponentially with increasing speed, and the mode and magnitude of the adjustment are appropriately stable with high application value.