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Objective To compare patient radiation dose during implantation of the second generation wireless pacemaker(Micra AV)and traditional dual-chamber pacemaker.Methods Data of 74 patients who received pacemaker implantation for bradycardia were retrospectively analyzed.According to the kind of pacemaker,the patients were divided into AV group(n=30)and traditional group(n=44).The perspective time,air kerma(AK),dose area product(DAP),number of movie sequences and total movie frames were compared between groups.Results AK,movie DAP,number of movie sequence and total movie frames in AV group were all higher than those in traditional group(all P＜0.05).No significant difference of the perspective time nor perspective DAP was found between groups(both P＞0.05).Patients'X-ray radiation projection range were essentially the same in both groups,most distributing on the left side of the bodies.Conclusion Compared with implantation of traditional dual-chamber pacemaker,implantation of Micra AV brought patient greater radiation dose from movie acquisition,while radiation dose from fluoroscopy were not significantly different.
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Objective:To compare the differences of actual absorbed doses of liver malignant tumors after 90Y-selective internal radiation therapy (SIRT) evaluated by 90Y PET/CT and 90Y bremsstrahlung (BRS) SPECT/CT imaging, and to compare the image quality of the 2 imaging methods. Methods:Twenty-one patients (15 males and 6 females; age: (52.4±15.4) years) with liver malignant tumors (15 cases of primary liver cancer, 6 cases of liver metastases; 39 lesions) between September 2021 and August 2022 were retrospectively analyzed. All patients underwent both 90Y PET/CT imaging and 90Y BRS SPECT/CT imaging in the Department of Nuclear Medicine, Hainan Cancer Hospital. The ratios of the actual absorbed doses based on 90Y PET/CT imaging and 90Y BRS SPECT/CT imaging to the lowest standard absorbed dose(100 Gy) for tumor response were calculated. The image contrast and distinguishability of the two imaging methods were scored. Wilcoxon signed rank test and Wilcoxon rank sum test were used for data analysis. Results:The tumor absorbed doses evaluated by 90Y PET/CT and 90Y BRS SPECT/CT were 143.94(55.91, 233.48) Gy and 107.82(53.59, 157.53) Gy respectively. The doses evaluated by 90Y PET/CT were higher than the standard threshold in 24 lesions, while 19 lesions showed higher evaluated doses by 90Y BRS SPECT/CT than the standard threshold. Compared with 90Y PET/CT, 90Y BRS SPECT/CT underestimated the tumor absorbed dose of -24.25%(-32.32%, -12.14%). The ratio of dose evaluated by 90Y PET/CT to the lowest standard threshold was 1.33(0.56, 1.91), which was higher than that of dose evaluated by 90Y BRS SPECT/CT to the lowest standard threshold (0.97(0.47, 1.25); z=0.04, P<0.001). PET/CT image contrast was scored 0, 1, 2, 3 in 2, 2, 12, 23 lesions respectively, and SPECT/CT image contrast was scored 0, 1, 2, 3 in 2, 3, 16, 18 lesions respectively ( z=-1.29, P=0.199). The distinguishability scores of 0, 1, 2 based on PET/CT images were found in 3, 15, 21 lesions, while those based on SPECT/CT images were found in 4, 32, 3 lesions respectively ( z=-2.79, P=0.005). Conclusion:90Y PET/CT imaging is superior to 90Y BRS SPECT/CT imaging in radiation dose evaluation and tumor focus differentiation in patients with liver malignant tumors after 90Y-SIRT.
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Introducción. Las radiografías continúan usándose ampliamente, subestimando los riesgos. Esto sucede, especialmente, en las unidades de cuidado neonatal, lo que implica que los neonatos reciben una dosis de radiación ionizante mayor que los adultos. Objetivo. Cuantificar las dosis de radiación recibidas al tomar radiografías y evaluar los posibles factores asociados con el aumento de la dosis. Materiales y métodos. Se llevó a cabo un estudio observacional de 160 neonatos de la Unidad de Recién Nacidos del Hospital Universitario San Ignacio, Bogotá, Colombia. Se consideró como variable dependiente la dosis de entrada en piel por cada radiografía. Se hizo la caracterización de los pacientes, seguida de un análisis multivariado con regresión lineal múltiple para identificar factores asociados. Resultados. Se analizaron 160 pacientes y 492 radiografías en total. Entre los hallazgos más frecuentes, se encuentran: pacientes de sexo masculino (n=87; 54,4 %), nacimiento por cesárea (n=122; 76,3 %) e indicación de toma de radiografías por dificultad respiratoria (n=123; 24,9 %). El 1,8 % (n=9) de los pacientes no tenían una indicación para la toma de la radiografía. La radiografía más frecuente fue la de tórax (n=322; 65,4 %). La mayoría de las radiografías se tomaron con el equipo computarizado (n=352; 71,5 %) y no con el digital (n=140, 28,4 %). La mediana de la dosis de entrada en piel con el equipo computarizado fue de 0,112 mGy (0,022; 0,134 mGy) y, con el equipo digital, de 0,020 mGy (0,019, 0,022 mGy). Conclusiones. Se cuantificaron las dosis de radiación absorbida en neonatos, general y específica, con el equipo computarizado y el digital. Se identificaron mayores dosis con el equipo computarizado. Se reconoció la interacción entre el equipo computarizado con menores edades gestacionales corregidas como principal factor para el aumento de la dosis. Además, se reconoció la relación entre el equipo computarizado y una menor edad gestacional corregida, como principal factor para una mayor dosis.
Introduction. Radiographs are still widely used, underestimating the risks. This situation is frequent in neonatal care units, generating radiation doses than in adults. Objective. To quantify the received radiation doses when performing radiographs on neonates and the possible factors associated with higher doses. Materials and methods. We performed an observational study of 160 neonates from the newborn unit of the Hospital Universitario San Ignacio, Bogotá, Colombia. We considered the input dose of each radiograph as the dependent variable. Patients were characterized and a multivariate analysis with multiple linear regression was performed to identify associated factors. Results. We analyzed 160 newborns and 492 radiographs. The most frequent findings were male patients (n=87, 54.4%), cesarean delivery (n=122, 76.3%), and radiograph indication for respiratory distress (n=123, 24.9%). One-point eight percent of the patients (n=9) did not have radiograph indication. The most frequently taken radiograph was chest (322, 65.4%). Most radiographs were taken with a computerized equipment (n=352, 71.5%), compared to a digital one (n=140, 28.4%). The median input dose with computerized equipment was 0.112 mGy (0.022, 0.134 mGy), and with the digital equipment was 0.020 mGy (0.019, 0.022 mGy). Conclusions. The general and specific absorbed radiation doses were measured in neonates with a computerized and a digital equipment. We identified higher doses with the computerized equipment. In addition, it was recognized the correlation between computerized radiography equipment with lower corrected gestational ages as the main factor for dose increase.
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Radiation Dosage , Infant, Newborn , Radiation , Radiography , Risk FactorsABSTRACT
Objective To explore the feasibility of low-dose CT-guided Hookwire localization of lung nodules in patients with body mass index(BMI)≤22 kg/m2.Methods Totally 53 BMI≤22 kg/m2 patients with 66 lung nodules were prospectively enrolled,CT-guided Hookwire localization of lung nodules were performed.According to the dose of CT scanning,the patients were divided into conventional dose group(group A,25 patients with 32 lung nodules)or low dose group(group B,28 patients with 34 lung nodules),while previous conventional dose CT scanning data of patients in group B were taken as control(group C).The image quality of group A and group B were scored using a 5-point scale,and the displaying of lung nodules in group B and group C were scored using a 3-point scale.The basic information of patients,lung nodules location,type,CT value,the maximum diameter,image quality score,puncture times,complications,as well as volume CT dose index(CTDIvol),dose-length product(DLP)and effective dose(ED)were compared between group A and B,so were score of lung nodules display,the maximum diameter and CT value of nodules between group B and C.Results No significant difference of basic information,the location,type,CT value,the maximum diameter,puncture times of lung nodules nor complications was found between group A and B(all P＞0.05).The quality score of group B(4[3,4])was lower than that of group A(5[4,5])(P＜0.05)but all greater than 3 and met the needs of puncturing.CTDIvol,DLP and ED of group B were lower than those of group A(all P＜0.05).There was no significant difference of the maximum diameter,CT value nor score of lung nodules display between group B and C(all P＞0.05).Conclusion Low-dose CT-guided Hookwire localization of lung nodules was feasible in patients with BMI≤22 kg/m2.
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Objective To observe the feasibility of low tube voltage scanning technology in CT-guided cryoablation therapy of liver cancer.Methods Twenty-one patients who underwent routine CT(tube voltage 120 kV)-guided cryoablation of liver cancer(group A)were retrospectively enrolled,while low tube voltage(100 kV)CT-guided cryoablation of liver cancer was prospectively performed in 23 patients(group B).CT scanning were performed before and after ablation with automatic tube current mode(50-450 mA),and adaptive statistical iterative reconstruction(ASIR)algorithm was used for image reconstruction(reconstruction percentages of 40%)of both groups.The subjective scores and objective evaluations of CT image quality before and after treatment were compared between groups,so as the treatment effect and patient's radiation dose(volume CT dose index[CTDIvol]).Results No significant difference of subjective scores,objective evaluations of CT image quality nor treatment effect was detected between groups(all P＞0.05).Before and after treatment,CTDIvol of patients in group A was significantly higher than that in group B(btoh P＜0.001).Conclusion Low tube voltage scanning technology could be used for CT-guided cryoablation of liver cancer,which might ensure image quality without affecting evaluation on cryoablation effect and reduce radiation dose combined with ASIR algorithm.
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Objective To observe the value of virtual non-contrast(VNC)image combined with 40 keV virtual monoenergetic image(VMI)for reducing radiation dose of CT enterography(CTE)based on dual-layer spectral detector CT(DLCT).Methods Data of 63 patients with inflammatory bowel disease(IBD)who underwent CT true non-contrast(TNC)scanning and dual-phase contrast scanning were retrospectively analyzed.CT values,noise(SD),signal-to-noise ratio(SNR),contrast-to-noise ratio(CNR)of lesion/tissue/structure on TNC,conventional arterial and venous phase,VNC of arterial and venous phase(VNCa and VNCv)and 40 keV VMI images were measured,and dose-length product(DLP),volume CT dose index(CTDIvol)and effective dose(ED)were calculated,respectively.Objective evaluation was performed to compare TNC and VNC,also between conventional arterial phase and 40 keV VMI.Subjective score and radiation dose were compared between conventional CT and VNC combined with 40 keV VMI.Results No significant difference of CT values of involved intestinal wall,non-involved intestinal wall nor psoas major muscle was found among TNC,VNCa and VNCv images(all P＞0.05).CT values,SNR and CNR of involved intestinal wall,non-involved intestinal wall and psoas major muscle on 40 keV VMI images were all higher than those on conventional arterial phase CT images(all P＜0.05).The subjective score of conventional CT and VNCv combined with 40 keV VMI images was 4(4,5)and 4(4,5),without significant difference(P＞0.05).Compared with conventional CT scanning,radiation dose of CTE using VNCv combined with 40 keV VMI decreased about 67.53％.Conclusion DLCT VNC combined with 40 keV VMI could reduce radiation dose of CTE.
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Objective:To evaluate the feasibility of artificial intelligence (AI) diagnosis of pulmonary nodules on virtual non-contrast(VNC) images derived from dual-layer detector spectral CT.Methods:Totally 52 patients who underwent non-contrast and dual-phase enhanced chest CT scan from May 2022 to November 2022 were enrolled in this study. The VNC images of lung were reconstructed based on venous phase data. CT values and image noise of lung parenchyma, signal-to-noise ratio (SNR) were measured. The dose-length product (DLP) of each scan was recorded and the effective dose ( E) was calculated. All of the objective indicators of image quality and radiation dose were compared by Paired t test. Image quality was evaluated subjectively by two radiologists and compared with Wilcoxon non-parametric test. Wilcoxon symbolic rank test was used to compare the sensitivity and false positive detection rate (FPDR) of AI diagnosis between two groups. Results:Compared with TNC, the noise of venous VNC image was decreased by 13.8%, SNR increased by 14.9%, and both of DLP and E decreased by 33.3% ( t=5.82, -5.35, 22.93, 22.92, P <0.05). There were no significant differences in CT values and subjective scores between 2 groups ( P >0.05). For different types of pulmonary nodules, there was no statistical difference in the sensitivity of AI diagnosis between two groups ( P >0.05). For solid nodules with diameter ≤4 mm and all pulmonary nodules in general, FPDR in VNC group was slightly increased with statistical significance ( Z=-2.03, -3.09, P<0.05), while for other types of pulmonary nodules, there was no statistical difference ( P >0.05). Conclusions:The VNC images of thoracic venous phase based on spectral CT can significantly reduce the radiation dose of patients while the image quality and the AI diagnostic sensitivity of pulmonary nodules remain unchanged, and the FPDR without significantly increase. And it could replace TNC for daily routine.
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Objective:To investigate the detection rate of pulmonary nodules (PN) by CT scan at different doses and the application value of artificial intelligence(AI) system assistance.Methods:From October 2019 to October 2021, 210 patients with PN in Beijing Hospital of Traditional Chinese Medicine, Capital Medical University, were retrospectively selected, and they were divided into the study group (106 cases) and the control group (104 cases) by CT scan at different doses. The control group used the conventional average dose (169 mAs) CT scan, the study group used an average low-dose (54 mAs) CT scan. The PN detection rate of different gender, age, body mass index (BMI) between the two groups were compared. The morphological characteristics, radiation dose, CT image quality between the two groups were compared. The diagnostic efficiency of radiologists and AI system was compared.Results:The detection rate of PN in the study group and the control group had no significant difference: 73.58% (78/106) vs. 80.77%(84/104), χ2 = 1.54, P>0.05. The detection rate of PN with different gender, age group and BMI in the two groups had no significant differences ( P>0.05). The diameter of nodules and the rates of calcification, cavitation, bronchial sign, lobar sign, burr sign and pleural adhesion sign in the two groups had no significant differences ( P>0.05). The mean effective tubular bulb dose, length product of radiation dose, total tubular bulb dose, radiation volume dose index in the study group were higher than those in the control group: (46.15 ± 7.38) mAs vs. (104.39 ± 10.53) mAs, (169.24 ± 19.77) mGy·cm vs. (427.17 ± 43.58) mGy·cm, (972.65 ± 58.34) mAs vs. (2 861.26 ± 181.37) mAs, (3.55 ± 1.16) mGy vs. (8.95 ± 2.07) mGy, there were statistical differences ( P<0.05). The excellent, good, acceptable, poor of 1.0 mm image quality in the study group were 26, 60, 18, 2, and in the control group were 32, 64, 8, 0, there was statistical difference ( u =1.71, P = 0.087). The excellent, good, acceptable, poor of maximum intensity projection (MIP) image quality in the study group were 58, 42, 6, 0 and in the control group were 70, 34, 0, 0, there was statistical difference ( u = 1.81, P = 0.070). The detection rate of PN by AI low-dose CT scan was higher than that of radiologists: 88.68%(94/106) vs. 73.58%(78/106), there was statistical difference ( χ2 = 7.89, P = 0.005). Conclusions:The low-dose CT chest scans for PN, the results of detection rate, morphological characteristics, CT image quality are basically the same as those of conventional-dose CT chest scans, and can greatly reduce the radiation dose, which is more suitable for PN screening, and combined with AI system can significantly improve the detection rate of PN.
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Objective:To explore the value of the deep learning image reconstruction (DLIR) algorithm in improving the CT image quality of abdominal phantoms under different radiation doses by comparing the DLIR algorithm with the conventional Adaptive Statistical Iterative Reconstruction-V (ASIR-V) technique.Methods:Two groups with tube voltages of 100 kV and 120 kV (also referred to as the 100 kV and 120 kV groups, respectively) were involved. Each group was further divided into six subgroups based on different volumetric CT dose indices (CTDI vol: 2, 4, 6, 8, 10 and 15 mGy). Subsequently, CT images based on the filtered back projection (FBP) algorithm were obtained and were then reconstructed using the ASIR-V algorithm with different weights (ASIR-V 50%, 80%, and 100%) and the DLIR algorithm with different levels (DLIR-L, M, and -H). As a result, 84 groups of images were obtained in total. Afterward, this study compared and analyzed the variations in CT values, noise, signal-to-noise ratios (SNRs), contrast-to-noise ratios (CNRs), and subjective scores of various parts in various CTDI vol subgroups under different reconstruction conditions. In addition, the subjective scores of the image quality were compared using the Kruskal-Wallis H test, while objective indices and radiation doses were compared through the univariate analysis of variance (ANOVA) and the paired t test. Results:Under the same tube voltage, there were statistically significant differences in the noise, SNRs, and CNRs of various parts in various CTDI vol subgroups under different reconstruction conditions ( F = 415.39, 315.30, P < 0.001), while there was no statistically significant difference in the noise, SNRs, and CNRs of images constructed using ASIR-V 50% and DLIR-L ( P > 0.05). Under different tube voltages, the subjective scores of both groups show statistically significant differences (100 kV group: H = 13.47, P = 0.036; 120 kV group: H = 12.99, P = 0.043). Moreover, two physicians offered consistent subjective scores, with Kappa values > 0.70. Among these images, DLIR-H images showed the highest subjective scores, followed by DLIR-M and ASIR-V 50% images, which had roughly consistent subjective scores. Moreover, the subjective scores of the 100 kV group were slightly higher than those of the 120 kV group. With the ASIR-V 50% images of the subgroup with a CTDI vol of 15 mGy as references, the DLIR-L, -M, and -H reduced radiation doses by more than 30%, 70% and 85%, respectively on the premise that diagnostic requirements were met. Conclusions:The DLIR algorithm can not only significantly reduce the image noise and improve the image quality, but also effectively decrease the radiation doses on the premise of meeting the diagnostic requirements. It is recommended that 100 kV tube voltage combined with a medium- or high-level DLIR algorithm should be applied to low-dose abdominal CT scans in clinical applications.
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Objective:To investigate the difference of dose distribution between intensity-modulated photon radiotherapy (IMRT) and intensity-modulated proton radiotherapy (IMPT) in patients with non-small cell lung cancer.Methods:The clinical data of 8 patients with stage Ⅱ-Ⅲ non-small cell lung cancer who received radiotherapy in Ion Medical center of the First Affiliated Hospital of University of Science and Technology of China from November 2020 to April 2022 were retrospectively analyzed. IMRT and IMPT radiotherapy plans were created for each patient separately, the main evaluation indicators were targeted area dose distribution parameters [homogeneity index (HI), conformity index (CI) and the percent volume of volume wrapped by 95% and 100% of prescription dose profile in the targeted area (V 95% and V 100%)], and the average dose (D mean) to the organ at risk and the percent volume of a certain relative biological effect (RBE) dose exposure [D mean, V 5 Gy(RBE) and V 20 Gy(RBE) of ipsilateral lung, D mean, V 5 Gy(RBE) and V 20 Gy(RBE) of bilateral lung, D mean, V 30 Gy(RBE) and V 40 Gy(RBE) of heart, maximum dose (D max) of spinal cord, and D mean of esophageal]. Results:In comparison with IMRT, IMPT reduced the levels of dose parameters in bilateral lung, ipsilateral lung, spinal cord, esophagus, and heart with statistically significant differences (all P < 0.05), especially in D mean of bilateral lung [(4.1±1.8) Gy (RBE) vs. (6.9±1.9) Gy (RBE)], V 5 Gy(RBE) [(15.9±7.1) % vs. (28.5±8.6)%], V 20 Gy(RBE) [(7.4±3.5)% vs. (10.1±3.5)%], and D mean of ipsilateral lung [(9.1±4.5) Gy (RBE) vs. (11.9±3.3) Gy (RBE)], all decreased significantly (all P < 0.001), but the differences in the levels of targeted area dose distribution parameters between them were not statistically significant (all P > 0.05). Conclusions:For patients with non-small cell lung cancer, IMPT is superior to IMRT in the protection of bilateral lung, ipsilateral lung, spinal cord, esophagus and heart.
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Objective:To investigate the application value of KARL iterative algorithm combined with low-dose CT scanning in young and middle-aged patients with femoral neck fractures.Methods:The clinical data of 132 young and middle-aged patients with femoral neck fractures diagnosed by clinical and CT scan in Taizhou Bo′ai Hospital from August 2019 to May 2022 were collected. There were 68 cases in the conventional dose group reconstructed by projection, and 64 cases in the low dose group reconstructed by KARL iterative algorithm. The subjective image quality score, the excellent and good rates and CT value, signal to noise ratio (SNR) were compared between the two groups. The effective dose (ED), CT dose index (CTDIvol), dose-length product (DLP) were compared between the two groups.Results:There were no significant differences in subjective image quality score, the excellent and good rates between the two groups ( P>0.05). There were no significant differences in CT values and SNR of the trabecular dense area at the central level of the femoral head, the iliopsoas muscle at the same level, and the anterior abdominal wall or buttocks subcutaneous fat at the same level between the two groups ( P>0.05). The levels of CTDIvol, DLP and ED in he low-dose group were lower than those in the conventional dose group: (3.35 ± 1.05) mGy vs. (12.90 ± 2.92) mGy, (66.33 ± 20.26) mGy/cm vs. (253.12 ± 58.57) mGy/cm, (0.99 ± 0.30) mSv vs. (3.79 ± 0.88) mSv, there were statistical differences ( P<0.05). Conclusions:Based on KARL iterative algorithm combined with low-dose CT scanning has no significant effect on the clinical diagnosis and classification of femoral neck fractures, the scanning image has a high objective evaluation value, and can effectively reduce the radiation dose received by patients, which is useful for clinical preoperative diagnosis and surgical planning.
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RESUMEN Fundamento: aún no existe una forma óptima para determinar la dosis absorbida por los tumores; este desconocimiento es la causa de que la dosis final del tratamiento sea impredecible. Por esta causa los pacientes pueden estar recibiendo dosis mayores que las mínimas requeridas para su correcto diagnóstico. Objetivo: crear un código fuente para un proyecto de aplicación del programa GATE en la simulación de la dosis absorbida en radioterapia molecular, por método Montecarlo, para un maniquí de Giap. Métodos: se realizó la simulación por método de Montecarlo a partir de modelar el maniquí de Giap, mediante la plataforma de simulación GATE. Se compararon los resultados obtenidos con la información reflejada en la bibliografía sobre las mejores prácticas estandarizadas. Resultados: se confeccionó un código fuente implementado en GATE para la determinación de la dosis absorbida en radioterapia molecular. Se obtuvo distribución no uniforme de dosis en un medio de actividad uniforme y un 2 % de incertidumbre aproximado (en buena correspondencia con los valores reportados en la literatura), los resultados permiten afirmar que la simulación de dosis por medio de la plataforma GATE es confiable, de poco gasto computacional y altamente recomendable. Conclusiones: es recomendable utilizar la plataforma GATE para la simulación del cálculo de la dosis absorbida por ser rápida, de bajo costo computacional y confiable.
ABSTRACT Background: there is still no optimal way to determine the dose absorbed by tumors; this lack of knowledge is the reason why the final dose of treatment is unpredictable. For this reason, patients may be receiving doses greater than the minimum required for their correct diagnosis. Objective: to create a source code for an application project of the GATE program in the simulation of absorbed dose in molecular radiotherapy, by Monte Carlo method, for a Giap phantom. Methods: the simulation was carried out by the Montecarlo method from modeling the Giap phantom, using the GATE simulation platform. The results obtained were compared with the information reflected in the bibliography on standardized best practices. Results: a source code implemented in GATE was prepared for the determination of the absorbed dose in molecular radiotherapy. Non-uniform distribution of doses was obtained in a medium with uniform activity and an approximate 2% uncertainty (in correspondence with the values reported in the literature), the results allow to affirm that the dose simulation through the GATE platform is reliable, of little computational expense and highly recommended. Conclusions: it is advisable to use the GATE platform for the simulation of the calculation of the absorbed dose because it is fast, of low computational cost and reliable.
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RESUMEN Fundamento: los estudios híbridos producen una dosis total de radiación que es resultado de la dosis proveniente del radiofármaco y la emitida por la tomografía computarizada, por eso la optimización es indispensable. Objetivo: evaluar la relación de la dosis de tomografía computarizada con algunos parámetros de calidad de la imagen en protocolos de estudios híbridos. Métodos: para evaluar la calidad de la imagen se emplearon los maniquíes de Catphan y de Livermore en 12 protocolos preestablecidos de un equipo de tomografía por emisión del fotón único Mediso. Los datos de los descriptores de dosis de cada estudio se obtuvieron del cabezal DICOM. Se compararon los parámetros de calidad de imagen clásicos como ruido y la MTF 50 % para el maniquí de Catphan, y otros como la relación contraste ruido, el promedio de números de Hounsfield y su desviación estándar en las regiones de interés de los órganos correspondientes, en el maniquí de Livermore. Se analizó la relación de estos parámetros de calidad con los descriptores de dosis de los diferentes protocolos. Resultados: los parámetros relacionados con la calidad en el maniquí de Catphan no mostraron diferencias significativas (p<0,05) entre los diferentes protocolos para estudios híbridos. Se encontraron diferencias significativas entre los protocolos clínicos con diferentes calidades y el protocolo clínico estándar, para el maniquí antropomórfico, en la desviación estándar de los números de Hounsfield y en la relación contraste ruido (p<0,05). Conclusiones: el estudio de la relación contraste ruido y la desviación de los números de tomografía computarizada en las regiones de interés pueden servir de parámetro cuantitativo para la optimización de dosis en escenario clínico.
ABSTRACT Background: hybrid studies produce a total radiation dose that is the result of the dose imparted by the radiopharmaceutical and that emitted by the computed tomography, therefore optimization is essential. Objective: to evaluate the relationship of the computed tomography dose with some image quality parameters in hybrid study protocols. Methods: to evaluate the image quality, the Catphan and Livermore Phantom were used in 12 pre-established protocols of a Mediso single photon emission tomography equipment. The data for the dose descriptors for each study were obtained from the DICOM head. The classic image quality parameters such as noise and the MTF 50% for the Catphan manikin, and others such as the contrast-noise ratio, the average of Hounsfield numbers and their standard deviation in the regions of interest of the corresponding organs were compared, in Livermore's mannequin. The relationship of these quality parameters with the dose descriptors of the different protocols was analyzed. Results: the quality-related parameters in the Catphan manikin did not show significant differences (p <0.05) between the different protocols for hybrid studies. Significant differences were found between the clinical protocols with different qualities and the standard clinical protocol, for the anthropomorphic manikin, in the standard deviation of the Hounsfield numbers and in the contrast-to-noise ratio (p <0.05). Conclusions: the study of the contrast noise ratio and the deviation of the computed tomography numbers in the regions of interest can serve as a quantitative parameter for the optimization of doses in the clinical setting.
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Objective:To investigate the relationship between tube voltage kV value for head and neck CT angiography and body weight.Methods:A total of 120 patients with suspected vascular disease of the head and neck who underwent CT angiography of the head and neck in Beihai People's Hospital from January 2020 to May 2022 were included in this study. Patients were divided into three groups according to different tube voltages: group A (tube voltage 120 kV, n = 45), group B (tube voltage 100 kV, n = 45) and group C (tube voltage 80 kV, n = 30). Patients in group A were divided into group A1 (< 70 kg, n = 15), group A2 (70-85 kg, n = 15) and group A3 (> 85 kg, n = 15) according to different body weights. Patients in group B were divided into group B1 (< 70 kg, n = 15), group B2 (70-85 kg, n = 15) and group B3 (> 85 kg, n = 15) according to different body weights. Patients in group C were divided into group C1 (< 70 kg, n = 15) and group C2 (70-85 kg, n = 15) according to different body weights. Group C3 was not used. The contrast medium used was Loversol. The CT value, image noise, signal-to-noise ratio, contrast to noise ratio, and effective radiation dose of arterial vessels in each group were measured. The images were subjectively evaluated by two physicians who had senior professional titles using a 5-point rating scale. Results:Subjective score of image quality was all ≥ 3 grade in each group. There was no significant difference in image quality rating between groups A1 and A2 and groups B1, B2, and C1. There was a remarkable difference in image quality rating between groups A3, B3, and C2 and the other groups. There was a significant difference in the CT value of blood vessels at four different levels between groups A1, B1 and C1 ( F = 76.82, 64.62, 98.79, 71.85, all P < 0.001). There was a significant difference in CT value of blood vessels at four different levels between groups A2, B2 and C2 ( F = 159.82, 112.33, 108.22, 135.18, all P < 0.001). There was a significant difference in CT value of blood vessels at four different levels between groups A3 and B3 ( t = 4.40, 4.27, 3.91, 3.59, all P < 0.05). In groups B3 and C2, the image noise was remarkably increased, signal to noise ratio and contrast to noise ratio were remarkably decreased compared with those in the other groups. The effective radiation dose of arterial vessels in group B1 was 47% lower than that in group A1 and the effective radiation dose of arterial vessels in group C1 was 73% lower than that in group A1 ( F = 116.18, P < 0.001). The effective radiation dose of arterial vessels in group B2 was 49% lower than that in group A2, and the effective radiation dose of arterial vessels in group C2 was 66% lower than that in group A2 ( H = 35.40, P < 0.001). The effective radiation dose in group B3 was 35% lower than that in group A3 ( t = 3.59, P < 0.05). Conclusion:In CT angiography of the head and neck, the selection of tube voltage kV value is related to body weight. Tube voltage 80 kV is suitable for patients with a body weight < 70 kg, tube voltage 100 kV for patients with a body weight of 70-85 kg, and tube voltage 120 kV for patients with a body weight > 85 kg. These tube voltages can decrease effective radiation dose and ensure image quality, meeting the requirement for clinical diagnosis.
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Objective:To understand the current situation of CT radiation dose in children all over our country, and to explore the diagnostic reference level (DRL) of CT in children.Methods:The radiation dose reports of pediatric CT examination were collected end to November 30, 2021 and divided into five age groups: 0-1 month,>1 month-4 years,>4-10 years,>10-14 years and >14-18 years. There were 9 scanning item such as head, nasal sinus, temporal bone, neck, chest, abdomen, head enhanced CT, chest enhanced CT and abdomen enhanced CT. In each item, volume CT dose index (CTDI vol) and dose length product (DLP) were selected as radiation dose parameters, the 75% percentile were selected for DRL. The DRL results of head, chest and abdomen were compared with the DRL published by Chinese Society of Radiology and European Commission. Results:From March 2019 to November 2021, a total of 33 hospitals in 23 provinces were collected, including 20 children′s specialized hospitals, 11 women′s and children′s hospitals and 2 general hospitals, including 19 135 children′s CT scans. The DRL of 45 subgroups according to 5 age groups and 9 scanning items were obtained. The DRL results showed that the CTDI vol in five age groups was 26.9-42.8 mGy, and the DLP was 347-694 mGy·cm for head; 3.5-8.0 mGy, 54-293 mGy·cm for chest; and 6.3-13.2 mGy, 155-564 mGy·cm for abdomen. The DRL of the age group >4-10 years group in this investigation was agreed to the DRL of Chinese Society of Radiology. Compared with the European guidelines, there was little difference in the radiation dose of head scan, while the radiation dose of chest and abdomen in the young age group increased significantly. Conclusion:This survey reveals the radiation dose level distribution of children CT in our country. The radiation dose level of some items was inconsistent with the DRL of relevant international organizations. So our own DRL is needed to be set up according to the actual clinical reality of our country as a guideline.
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Objective:To investigate the efficiency of deep learning image reconstruction (DLIR) algorithm in the image quality and detection of hypovascular hepatic metastases under low radiation doses in comparison with adaptive statistical iterative construction-V (ASiR-V).Methods:Fifty-six patients with suspected hypovascular hepatic metastases who needed abdominal enhanced CT scans were collected prospectively in the First Affiliated Hospital of Zhengzhou University from January to April 2021. The patients received conventional radiation dose with tube current-time products of 400 mA CT scans in the first venous phase, low-dose CT scans in the second venous phase, which were set as tube current-time products of 280 mA for group A (19 cases), 200 mA for group B (19 cases) and 120 mA for group C (18 case), respectively. The images of first venous phase and 3 groups of second venous phase were both reconstructed with ASiR-V60% and high-DLIR (DLIR-H). Quantitative parameters [image noise, liver and portal vein signal to noise ratio (SNR), contrast to noise ratio (CNR)] and qualitative parameters (overall image quality, lesion conspicuity, diagnostic confidence) were compared between ASiR-V60% and DLIR-H images, and the effective radiation dose (ED) and the lesion detectability of each group was recorded. The paired t test was used to compare quantitative parameters, whereas the Wilcoxon signed-rank test of paired data was used to compare qualitative parameters. Results:In the second venous phase, ED was (5.56±0.35) mSv in group A, (3.88±0.23) mSv in group B, and (2.42±0.23) mSv in group C, with a decrease of 30%, 50% and 70% compared with the first venous phase, respectively. Moreover, with the decrease of radiation dose, the noise gradually increased, and the CNR lesions, SNR liver and SNR portal vein all gradually decreased. DLIR-H images had statistically better quantitative scores than ASiR-V60% images when the same radiation dose was applied (all P<0.001). Furthermore, the qualitative parameters of each group decreased with the decrease of radiation dose. Under the same radiation dose, the overall image quality, lesion conspicuity and diagnostic confidence of DLIR-H were higher than those of ASiR-V60% (all P<0.001). All lesions [100% (84/84)] were detected by ASIR-V60% and DLIR-H in group A, 92.0% (75/81) in group B, and 88.0% (79/89) in group C. Conclusions:Compared with ASiR-V60%, DLIR-H could reduce image noise, improve overall image quality and lesion conspicuity of hypovascular hepatic metastases as well as increase diagnostic confidence under different radiation doses.
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Objective:To estimate the radiation dose (RD) to the public from patients undergoing 177Lu-prostate specific membrane antigen (PSMA)-617 therapy, and provide reference for the formulation of radiation protection measures. Methods:From July 2020 to January 2021, 10 patients with prostate cancer (age (71.1±5.9) years) who received 177Lu-PSMA-617 therapy in the Affiliated Hospital of Southwest Medical University were retrospectively analyzed. According to the different doses of 177Lu-PSMA-617, the patients were divided into the low-dose (5.55-6.29 GBq) group and high-dose (6.70-8.94 GBq) group. Respectively at 5, 30 min and 1, 2, 4, 24, 48, 72, 96, 144 h after intravenous injection of 177Lu-PSMA-617, whole-body initial dose-equivalent rate (DR) was measured with a radiation-survey meter at 0.3, 1.0 and 2.0 m from the patients. The statistics of ROI were analyzed by HERMES, and the corresponding equations were obtained by fitting the curve regression with double exponential function model. On the basis of human social contact model proposed by the National Council on Radiation Protection and Measurements (NCRP), the RD to the public from the patient discharged from the hospital at different times after completing the 177Lu-PSMA-617 injection was estimated. Results:All patients were discharged from the hospital at 72 h after treatment. The initial DR at 0.3, 1.0 and 2.0 m were (12.6±3.3), (4.7±1.2) and (1.6±0.4) μSv/h, respectively, and the RD to the co-sleeping partner, family members and colleagues who were in contact during the day were (999±253), (121±29) and (160±39) μSv, respectively. If the patients were discharged at 48 h after treatment, the RD to the adult family members could be controlled ≤5 mSv, and the RD to colleagues and children could be controlled ≤1 mSv. Starting from the injection of 177Lu-PSMA-617, the restriction duration for co-sleeping partner and colleagues were both 2 d and the restriction duration for children were 2 d (high-dose group) or 1 d (low-dose group). The patients needed to limit the time for public transportation from the 1st to 4th day after treatment, and there was no restriction from the 5th day. Conclusion:According to the current RD restrictions on the public, 177Lu-PSMA-617 is a relatively safe treatment modality for prostate cancer if good safety precautions are taken.
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Objective:To evaluate the advantages of PET automatic drug infusion system in nuclear medicine nursing by comparing radiation dose and precision injection between artificial injection and automatic injection.Methods:From August 2021 to September 2021, 40 patients (27 males, 13 females, average age: 59.6 years) were divided into two groups (20 patients in each group) for the injection of 18F-FDG by artificial injection and automatic injection in Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine. Portable radiation detector was used to measure the peak values of dose-equivalent rate in the arm and trunk of the nurse during the administration. The duration of administration process was recorded and the annual radiation doses were estimated and compared between the two injection methods. Independent-sample t test was used to compare the differences of injection parameters between two methods. Results:Based on 5 000 patients injected annually by artificial injection, the estimated annual radiation doses were about 220.19 mSv in the arm and 2.09 mSv in the trunk, while the radiation doses were approximately 0.19 and 0.08 mSv by automatic administration, respectively. Compared with the artificial injection, the automatic drug infusion system could reduce by 99% and 95% of equivalent doses in the arm and trunk, respectively. The significant difference was found in the empty needle activity between artificial injection and automatic drug infusion system ((18.87±7.77) and (0.22±0.19) MBq; t=10.65, P<0.001), while there were no statistical differences in full needle activity, injection activity and injection/prescription activity ratio ( t values: from -0.03 to 1.37, all P>0.05). Conclusion:PET automatic drug infusion system provides better radiation protection for nuclear medicine nursing.
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Objective:To evaluate the effectiveness of deep learning reconstruction (DLR) compared with hybrid iterative reconstruction (Hybrid IR) in improving the image quality in chest low-dose CT (LDCT).Methods:Seventy-seven patients who underwent LDCT scan for physical examination or regular follow-up in Peking Union Medical College Hospital from October 2020 to March 2021 were retrospectively included. The LDCT images were reconstructed with Hybrid IR at standard level (Hybrid IR Stand) and DLR at standard and strong level (DLR Stand and DLR Strong). Regions of interest were placed on pulmonary lobe, aorta, subscapularis muscle and axillary fat to measure the CT value and image noise. The signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated. Subjective image quality was evaluated using Likert 5-score method by two experienced radiologists. The number and features of ground-glass nodule (GGN) were also assessed. If the scores of the two radiologists were inconsistent, the score was determined by the third radiologist. The objective and subjective image evaluation were compared using the Kruskal-Wallis test, and the Bonferroni test was used for multiple comparisons within the group.Results:Among Hybrid IR Stand, DLR Stand and DLR Strong images, the CT value of pulmonary lobe, aorta, subscapularis muscle and axillary fat had no significant differences (all P>0.05), but the image noise and SNR of pulmonary lobe, aorta, subscapularis muscle and axillary fat had significant differences(all P<0.05), and the CNR of images had significant difference( P<0.05), too. The CNR of Hybrid IR Stand images, DLR stand images and DLR strong images were 0.71 (0.49, 0.88), 1.06 (0.78, 1.32) and 1.14 (0.84, 1.48), respectively. Compared with Hybrid IR images, DLR images had lower objective and subjective image noise,higher SNR and CNR (all P<0.05). The scores of DLR images were superior to Hybrid IR images in identifying lung fissures, pulmonary vessels, trachea and bronchi, lymph nodes, pleura, pericardium and GGN (all P<0.05). Conclusions:DLR significantly reduced the image noise, and DLR images were superior to Hybrid IR images in identifying GGN in chest LDCT while maintaining superior image quality at relatively low radiation dose levels. Thus DLR images can improve the safety of lung cancer screening and pulmonary nodule follow-up by CT.
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Objective:To explore current status of scanning protocol and radiation dose of coronary CT angiography (CCTA) in China from 2017 to 2018.Methods:Cluster sampling was conducted according to the number and distribution of tertiary and secondary hospitals in provinces across the country, and 75 hospitals (30 secondary hospitals and 45 tertiary hospitals) were finally included. The patients who underwent CCTA from October 2017 to May 2018 were systematically sampled, and 1 312 patients were finally included. Patients were divided into two groups according to the level of hospital. Basic clinical characteristics were collected, including age, sex, height, weight, CT scanning equipment, scanning parameters, scanning model, post-processing scheme and radiation dose. Wilcoxon rank sum test, χ 2 tes were used in statistical analysis. Radiation dose was compared between different tube voltage, scanning model and post-processing solutions groups. Results:The ratio of employing low tube voltage (≤100 kV) was 35.4% (464/1 312). The rate of using low tube voltage in different weight groups (<60, 60-90,>90 kg) were 45.0%(126/280), 39.6%(256/647), 33.3%(8/24) in tertiary hospitals respectively, and 27.8%(25/90), 18.5%(49/265), 0(0/6) in secondary hospitals respectively. The rate of using low tube voltage in different weight groups (<60, 60-90,>90 kg) was significantly higher in tertiary hospitals than in secondary hospitals (χ2=34.25, 51.05, 207.05, P<0.001). Prospective electrocardiogram triggering model was used in 38.5% (505/1 312) of the patients. Application rate of iterative reconstruction was 82.5% (1 082/1 312). Among the patients who applied iterative reconstruction, tube voltage of 120 kV and above was used in 58.8% (636/1 082) of the patients. The effective radiation dose (ED) of CCTA was 11.84 (6.33, 16.66) mSv. The ED of CCTA examination in tertiary hospitals was slightly lower than that of secondary hospitals ( Z=-5.73, P<0.001). The ED of CCTA examination using prospective electrocardiogram triggering model was lower than that of retrospective electrocardiogram triggering model ( Z=-15.76, P<0.001). The ED of CCTA examination with iterative reconstruction [11.76 (6.94, 17.58) mSv] was slightly lower than those without iterative reconstruction ( Z=-3.45, P=0.004). Conclusions:The problems were focused on tube voltage fixation, low application proportion of low tube voltage and prospective electrocardiogram triggered protocol, and nonstandard application of iterative reconstruction technology during CCTA examination in the investigated hospitals. The nonstandard scanning protocol was an important causation of high ED in CCTA examination. Although the scanning standardization degree of tertiary hospitals was higher than that of secondary hospitals, but it still did not meet the guidelines.