Objective:To explore the application value of the double-low technique of auto-prescription technique combined with iterative reconstruction algorithm in CT pulmonary angiography (CTPA).Methods:A total of 86 patients who were clinically suspected of having pulmonary embolism and underwent CTPA examination in the First Affiliated Hospital of Dalian Medical University were prospectively collected and randomly assigned to a control group ( n = 45) and an observation group ( n = 41) according to the random number table method. In the control group, a tube voltage of 120 kVp was used with a standard iodine contrast agent dose of 60 ml, and images were reconstructed using the 40% adaptive statistical iterative reconstruction algorithm (ASIR-V). In the observation group, the tube voltage was set by auto-prescription technique, and 0.4 ml/kg of personalized low iodine contrast agent was used. Images were reconstructed with 40%, 60%, and 80% ASIR-V, respectively, and designated as observation 1, observation 2, and observation 3 respectively. The volume CT dose index (CTDI vol), dose-length product (DLP), and effective dose ( E) were recorded and compared among the four groups. The CT values and standard deviation (SD) of the main pulmonary artery, left and right pulmonary arteries, as well as the left and right pulmonary lobe arteries were measured, and the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of these arteries were calculated. Additionally, the SD value at the contrast medium concentration in the superior vena cava was measured, and the artifact index (AI) was subsequently calculated. Two observers independently assessed the visibility of the pulmonary arteries, image noise, and sclerosis artifacts in the superior vena cava using a blinded method. Results:The E in the observation group was 3.28 (2.08, 3.93) mSv, which was significantly lower than that in the control group [5.03 (4.86, 5.20)] mSv, and the difference was statistically significant ( Z = 174.00, P < 0.05). The contrast agent dosage in the observation group was 28 (25, 30) ml, which was lower than that in the control group (60 ml), and the difference was statistically significant ( Z = 0, P < 0.05). The CT values for the main pulmonary artery and the left and right pulmonary lobe arteries in the observation group were higher than those in the control group, and the differences were all statistically significant ( t = -3.65 to -3.89, P < 0.05). The SNR and CNR of the observation groups 2 and 3 were greater than those of the control group ( t = -9.20 to -2.98, P < 0.05). The consistency of subjective evaluations between the two observers was good ( Kappa = 0.729 - 0.879, P < 0.05). There was no statistically significant difference in the subjective score of pulmonary artery visibility between the control and observation group ( P > 0.05). The subjective scores for image noise in observation group 2 and group 3 were higher than those in the control group ( U =598.50, 654.00, P < 0.05). The presence of artifacts due to sclerosis in the superior vena cava was significantly lower in the observation group compared to the control group ( χ2 = 46.09, P < 0.001). Conclusions:The combination of auto-prescription technique with ASIR-V reconstruction algorithm and low contrast agent imaging protocol can reduce the radiation dose and contrast agent dose without compromising image quality, and enable personalized double low CTPA imaging.

Objective:To evaluate the image quality and radiation dose in contrast-enhanced thoracic-abdominal-pelvic CT using automatic tube voltage modulation (ATVM) coupled with artificial intelligence iterative reconstruction (AIIR) versus routine tube voltage combined with Karl-3D iterative reconstruction (Karl-3D IR), and to determine the optimal noise level for AIIR in contrast-enhanced thoracic-abdominal-pelvic CT.Methods:A total of 100 patients who underwent contrast-enhanced thoracic-abdominal-pelvic CT examination in the Affiliated Hospital of Hebei University from April to October, 2023 were randomly divided into group A and group B using a random number table, with 50 patients in each group. Group A was scanned using ATVM, and images were reconstructed using AIIR with 1-5 noise levels. Group B was scanned using tube voltage 120 kVp and images were reconstructed with Karl-3D IR and noise level 5. The single-to-noise ratio (SNR), contrast-to-noise ratio (CNR), effective dose (E), and size-specific dose estimate (SSDE) were recorded or calculated for all patients or images. Subjective evaluations of all images were performed. The quality of the reconstructed images using AIIR with 1-5 noise levels were compared and the optimal noise level of AIIR for image reconstruction was determined. Image quality and radiation dose were statistically analyzed for Group A (image reconstruction with optimal AIIR noise level) and Group B.Results:The mean SNR and mean CNR of the reconstructed images using AIIR with noise levels 1, 2, and 3 in group A were higher than those using AIIR with noise levels 4 and 5. The images reconstructed using AIIR with noise levels 3 and 4 scored higher in subjective assessment than those reconstructed using AIIR with noise levels 1, 2, and 5. Therefore, noise level 3 was optimal for AIIR in reconstruction of contrast-enhanced thoracic-abdominal-pelvic CT images. The mean SNR, mean CNR, and subjective evaluation score of group A using AIIR with noise level 3 were higher than those of group B using Karl-3D IR with noise level 5 ( P<0.001). The mean SSDE and the mean E of group A were reduced by 46% and 41%, respectively, compared with those of group B. Conclusions:ATVM technology combined with the AIIR algorithm can improve image quality and reduced patient radiation dose in contrast-enhanced thoracic-abdominal-pelvic CT. Noise level 3 is optimal for AIIR in the reconstruction of arterial-phase and venous-phase contrast-enhanced thoracic-abdominal-pelvic CT images.

In the field of radiotherapy, radiation-induced bystander and abscopal effects have attracted increasing attention. Studies indicate that these effects can extend from irradiated regions to non-irradiated cells or tissues. Radiation-induced bystander and abscopal effects related to lung can be categorized into lung-lung type, lung-extrapulmonary tissue type, and extrapulmonary tissue-lung type. The mechanism of its occurrence involves oxidative stress, immune response, and the role of extracellular vesicles. These effects exhibit a dual characteristic of inducing damage to normal tissues and increasing tumor therapeutic potential. Immune responses represent a pivotal mechanism, and the combination of radiotherapy with immunotherapy may enhance the incidence of abscopal effects. Researchers are exploring various intervention strategies to control or utilize these effects. Future studies should further investigate the underlying biological mechanisms, particularly in specific organs or sites, to improve the efficacy and safety of radiotherapy. This review explores the latest advances in lung-related radiation-induced bystander and abscopal effects, encompassing their definitions, classifications, mechanisms, functional characteristics, influencing factors, and intervention strategies.

Spatially fractionated radiation therapy (SFRT) dates from 1909. With the development of radiotherapy technologies and radiobiological theories, advances have been made in both the connotation and implementation method of SFRT. Additionally, clinical outcomes have further corroborated the role of SFRT as a palliative radiotherapy technique. This review summarizes the advances in the application of SFRT as a palliative radiotherapy technique from the aspects of the development history and related technologies, radiobiological basis, and clinical applications, in order to offer a reference for the implementation of SFRT.

Objective:To predict the occurrence of chronic radiation enteritis (CRE) in cervical cancer patients by developing a prediction model based on the combination of radiomic features derived from magnetic resonance imaging (MRI) scans and clinical parameters, in order to provide a reference for clinicians to determine the prognosis of these patients and offer them individualized diagnosis and treatment.Methods:A retrospective analysis was conducted on 111 cervical cancer patients who received radical radiotherapy at the First Affiliated Hospital of Anhui Medical University. Radiological features were extracted from the T1-weighted MRI images of local lesions of cervical cancer obtained before the radiotherapy. Features were selected using the least absolute shrinkage and selection operator (LASSO) to obtain the radiomics score. The radiomics scores and clinical parameters were assessed using univariate and multivariate logistic regression analyses, followed by the establishment of nomograms. The ability of radiomics to achieve CRE prediction was assessed using the area under the curve (AUC) and the calibration and decision curves.Results:Multivariate logistic regression analysis result revealed that the independent risk factors for identifying CRE in patients included radiomics score ( HR: 17.457, 95% CI: 5.540-55.009, P<0.001), tumor volume ( HR: 3.617, 95% CI: 1.293-10.115, P=0.014), and pelvic lymph node metastasis ( HR: 3.559, 95% CI: 1.013-12.501, P=0.048). The model combining radiomics and clinical data demonstrated high performance, with its AUCs of the training and validation groups (0.888 and 0.870, respectively) higher than those of the radiomics model (0.842 and 0.804, respectively) and the clinical data model (0.721 and 0.704, respectively). The analyses of calibration and decision curves confirmed the application value of clinical radiomic nomograms. Conclusions:The model combining radiomics and clinical data allows for accurate CRE prediction. Therefore, radiomic features have the potential to serve as a promising imaging biomarker for CRE.

Dose estimation of radiopharmaceutical therapy is essential for the accurate evaluation of its efficacy and safety, as well as for guiding subsequent clinical research. The dosimetry estimation process typically requires understanding of the in vivo spatial distribution and dynamic transportation of radionuclides, followed by calculation of the energy deposition in tumor target volume and organs at risk from ionizing radiation of varying types and energies released by accumulated radionuclides. This review focuses on advancements in the aforementioned research aspects and the relationship between internal radiation dose and biological effects. Furthermore, this review prospectively discusses future research directions, aiming to enhance comprehension of internal radiation dose estimation and provides theoretical frameworks and technical references for improving clinical evaluation accuracy in radiopharmaceutical therapy.

Ionizing radiation occurs not only during nuclear and radiological terrorist attacks or nuclear accidents but also in medical applications and daily life. In recent years, the potential toxic effects of low-dose ionizing radiation on the male reproductive system have raised public health concerns. Most specifically, for the testis, a highly sensitive target organ to ionizing radiation, there is an urgent need to determine the mechanisms underlying the association between radiation-induced spermatogenic failure and male infertility. Focusing on the potential injurious effects of low-dose ionizing radiation on spermatogenesis, this review presents a summary and analysis of various underlying mechanisms including oxidative stress, apoptosis, and DNA damage repair and reviews recent domestic and international strategies for protecting against radiation-induced reproductive system damage in order to offer references for future research on the injurious effects of low-dose radiation on spermatogenesis and relevant protection.

Objective:To investigate the effects of propionic acid produced by Akkermansia muciniphila on the radiosensitivity of colorectal cancer and the underlying mechanism. Methods:Normal human colon mucosal epithelial cells (NCM460) were used to determine the appropriate concentration of propionic acid. Human colorectal cancer cells (HCT-8) were treated with A. muciniphila-conditioned medium or propionic acid, followed by exposure to 6 Gy γ-ray irradiation, and cell survival and proliferation were measured by clone formation assay and Cell Counting Kit-8 (CCK-8) assay, respectively. A mouse model of colorectal cancer was established using azoxymethane/dextran sodium sulfate. The mice were divided into control model group, irradiation group, and irradiation+ propionic acid group. Their body weight, colorectal length, tumor count, and tumor area were recorded. The radiosensitizing effect of propionic acid was assessed with HE staining, immunohistochemical staining, and enzyme-linked immunosorbent assay. The mechanism was explored by using RT-PCR and flow cytometry. Results:CCK-8 assay showed that 1-mmol/L propionic acid had no significant effect on the proliferation of NCM460 cells ( P>0.05), which was used for subsequent experiments. Pretreated with A. muciniphila-conditioned medium or propionic acid, the survival and proliferation abilities of irradiated HCT cells were significantly decreased ( t=3.14-34.98, P<0.05). Compared with the irradiation group, the colorectal cancer mice in the irradiation+ propionic acid group showed a significantly longer colorectal length ( t=3.50, P<0.05) and a significantly smaller number of tumors ( t=3.48, P<0.05); the two groups had significantly smaller tumor areas than the control model group ( t=5.97, 7.30, P<0.05). HE staining and immunohistochemical staining showed that propionic acid restored colorectal structure, and decreased Ki67 expression in colorectal tissue ( t=14.50, 3.40, P<0.05). Propionic acid treatment significantly reduced the levels of the inflammatory factors interleukin-6 and tumor necrosis factor-α, as compared with the mice receiving irradiation alone ( t=4.86, 5.06, P<0.05). Irradiation plus propionic acid treatment significantly increased p53 expression and significantly aggravated G 2/M phase block and cell apoptosis ( t=20.35, 13.05, P<0.05). Conclusions:The A. muciniphila metabolite propionic acid plays a sensitizing role in radiation therapy for colorectal cancer by promoting G 2/M phase block and apoptosis in colorectal cancer cells.

Objective:To establish a dose-response curve of dicentric chromosomes and centromeric rings (dic+ r) in γ-ray irradiation-induced chromosomal aberrations in human peripheral blood lymphocytes through automated analysis.Methods:Peripheral blood samples from three healthy donors were irradiated in vitro at doses of 0, 0.5, 0.75, 1, 1.5, 2, 3, 4, and 5 Gy and a dose rate of 0.80 Gy/min using a 137Cs γ-ray source. Post-irradiation, lymphocytes were cultured based on standard protocols, harvested using an automatic cell harvester, and prepared on slides using an automatic slide preparation system. dic+ r were analyzed fully automatically using the DCScore software, and a dose-response curve of dic+ r was established through fitting and then validated using the CABAS software. Results:The dose-response curve followed a linear-quadratic model, i. e., y = 0.093 65+ 0.030 21 D+ 0.025 31 D2 ( R2 = 0.999 2), where y was the quantity of dic+ r and D was the absorbed dose of γ-ray irradiation (Gy). Doses to samples for blind validation were estimated using this curve, yielding deviations of less than 24% from the actual irradiation doses. Conclusions:The fully automated analysis of dic+ r in 137Cs γ-ray irradiation-induced chromosomal aberrations, followed by the construction of the dose-response curve, holds significant potential for rapid, high-throughput biodosimetry in large-scale nuclear emergencies.

Objective:To design and develop a cone-beam CT imaging system for small animals with continuously adjustable spatial resolution.Methods:The imaging system used an X-ray source with a focal spot size of 30 μm and a flat panel detector with a pixel size of 100 μm. On this premise, a " stepping-focusing-rotating" image acquisition mode was proposed, in which the " focusing" and " stepping" systems were sequentially embedded in the " rotating" system. In this acquisition mode, the X-ray source and flat panel detector were relatively stationary to form the " focusing" system. When the " stepping" system accurately transported the object to the scanning position, the " focusing" system could achieve adjustable spatial resolution by making linear motion around the object to be scanned according to different experimental requirements. Finally the " rotating" system achieve high-quality imaging.Results:The variable spatial resolution of small animal CBCT ranges from 35.7 μm to 71.4 μm, and the FOV ranges from 39.6 mm to 108.0 mm. The conversion time for the limit spatial resolution is 19.125 s, which allowed accurate 3D reconstruction of normal mice at different resolutions with high reproducibility.Conclusions:A cone-beam CT suitable for small animals has been developed, whose spatial resolution and FOV can be adjusted arbitrarily within a certain range, which can meet the different imaging requirements in rodent experiments.