Objective:By comparing the effects of installing 3d-printed bolus with or without positioning holes on the skin fit and patient dose distribution,the advantages and disadvantages of the two installation methods in the application of radiotherapy after radical breast cancer surgery were evaluated,and the reference was provided for clinical application.Methods:A total of 48 patients(34 patients with and 14 patients without positioning holes)who received radiotherapy for breast cancer in Suining Central Hospital from December 2022 to Au-gust 2024 were randomly selected.Three dimensional reconstruction of the air gap between the patient body surface and the 3d-printed bolus was conducted,and the tissue dose distribution of each case was analyzed.Comparative analysis was conducted using t-test to ana-lyze the differences of the skin fit and the key dosimetric indexes of target areas and organs at risk between the two bolus installation meth-ods.Results:The mean values of the maximum air gap height,air gap area and air gap volume of the group with positioning holes were lower than those of the group without positioning holes(P<0.05),and the skin fit showed better consistency.The target area conformity in-dex(CI),homogeneity index(HI),and affected lung radiation acceptance(V20,V5)of patients with positioning holes were better than those of patients without positioning holes(P<0.05).There was no significant difference in target area coverage of prescription dose,cardiac dose Dmean and spinal cord dose Dmax between two groups(P>0.05).Conclusions:The skin fit,dosimetric indexes of patient target area and or-gans at risk of 3d-printed bolus with positioning holes were superior to those without positioning holes,showing significant advantages in clinical applications.

Objective:To explore the feasibility of automatic target volume tracing in the Elekta Unity magnetic resonance imaging (MRI)-guided radiotherapy system and to further enhance the real-time target volume tracing performance of MRI-guided radiotherapy by introducing the deep learning technology based on a large Transformer model.Methods:A total of 4 661 frames of cine MRI binary images from 75 patients with malignant tumors in the chest/abdomen who were treated with MRI-guided radiotherapy were retrospectively collected as a training set. Another 500 frames of cine MRI binary images from 10 patients were collected as an independent test set. A module for medical image format conversion was developed to convert binary images into medical meta-images. The outer contours of tumor target volumes in the cine MRI images of the test set were manually delineated as actual control labels. With the first frame of the cine MRI images of each patient as the reference image and the other frames as motion images, a Transformer-based deep learning model was constructed to describe the deformable vector field (DVF) of motion images relative to the reference image. The Dice similarity coefficient (DSC), the 95% Hausdorff distance (HD 95), the negative Jacobian determinant (NegJ), and the average processing time per frame of cine MRI images were calculated. These values were compared to those of the conventional B-Spline scheme to quantitatively assess the target volume tracing accuracy, DVF physical plausibility, and execution efficiency of the Transformer-based deep learning model. Results:The Transformer-based deep learning model constructed in this study delivered superior target volume tracing performance, with improved DSC [(0.84 ± 0.05) vs. (0.74 ± 0.16), t = 11.44, P < 0.05] and HD 95 [(9.25 ± 2.98) vs. (14.70 ± 8.55) mm, t = -11.83, P < 0.05]. Furthermore, this model reduced the average image processing time from 1.95 s to 30.99 ms, enhancing the efficiency by two orders of magnitude. Besides, this model yielded NegJ similar to that of the B-Spline scheme. This suggests that the DVF extracted using this model had comparable physical plausibility with that obtained using the B-Spline scheme. Conclusions:The Transformer-based deep learning model for automatic target volume tracing fills the functional gap of the Elekta Unity MRI-guided radiotherapy system, facilitating relatively accurate, efficient automatic tracing of moving tumor targets in the chest and abdomen.

Objective To explore the effectiveness and safety of hypofractionated radiotherapy(HFRT)combined with transcatheter arterial chemoembolization(TACE)for metachronous hepatic oligometastasis from nasopharyngeal carcinoma(NPC).Methods The clinical data of patients with metachronous hepatic oligometastasis from NPC,who received HFRT combined with TACE treatment at the Sichuan Provincial Cancer Hospital of China from January 2012 to October 2022,were retrospectively analyzed.The 3-year and 5-year overall survival(OS),progression-free survival(PFS),local recurrence-free survival(LRFS),no extrahepatic distant metastasis survival(EMFS),and treatment-related adverse reactions were analyzed.Results A total of 55 patients were enrolled in this study,including 36 males and 19 females,the median age at the time of occurring metachronous hepatic oligometastasis was 44(27-75)years.The 3-year and 5-year OS,PFS,LRFS,EMFS were 67.8％and 40.0％,55.8％and 30.0％,72.7％and 56.5％,63.6％and 56.5％,respectively.The subgroup analysis indicated that the treatment course of TACE ≥3 cycles could significantly improve the PFS of patients with oligometastasis.HFRT combined with TACE treatment was well tolerated by all patients,and the incidence of Grade Ⅲ-Ⅳadverse reactions was quite low.Conclusion For the treatment of metachronous hepatic oligometastasis from NPC,HFRT combined with TACE is clinically effective,besides,the patients can well tolerate the therapeutic scheme.

Objective:To explore the clinical efficacy of the sixth generation CyberKnife (M6) in treating patients with brain metastases, and analyze clinical characteristics and dosimetric factors.Methods:Clinical data of patients with brain metastases who received CyberKnife treatment at Sichuan Cancer Hospital from April 2023 to March 2024 were retrospectively analyzed. All patients were treated with CyberKnife with 6 MV X-ray. According to the maximum diameter of brain metastases, the radiation prescription dose of brain metastases was adjusted. The tumor remission, recurrence, 6-month and 1-year overall survival (OS), local control (LC) of intracranial target lesions, progression-free survival (PFS), distant metastasis-free survival (DMFS) of intracranial brain metastases and adverse reactions were evaluated. According to the median biological dose, the survival difference between the groups was compared. Survival analysis was conducted by Kaplan-Meier method. Survival differences among different groups were analyzed by log-rank test.Results:A total of 63 eligible patients with brain metastases were enrolled, with a median age of 59 years (rang: 36-80 years). Among them, 47 patients were diagnosed with primary tumors originating from the lungs, 16 patients with primary tumors originating from other organs; 44 patients with single brain metastases, and 19 patients with 2-3 lesions, respectively. The median biological dose was 67.2 Gy (rang: 47.4-86.4 Gy), and the median single dose was 8 Gy/F (rang: 4-24 Gy/F). The follow-up was conducted until July 15, 2024. The median follow-up time for the entire group was 9 months (rang: 2-15 months). Among the 87 target lesions treated with CyberKnife, 11 patients corresponding to 14 target lesions experienced local recurrence. And the 6-month and 1-year LC rates were 92.5% and 70.9%, respectively. Ten patients corresponding to 16 target lesions died. And the 6-month and 1-year OS rates were 92.7% and 74.8%, respectively. Thirty-five patients corresponding to 50 target lesions experienced disease progression. And the 6-month and 1-year PFS rates were 64.3% and 25.5%, respectively. Thirty-three patients corresponding to 48 target lesions showed distant metastasis outside the target lesions, with a 6-month DMFS of 67.0% and a 1-year DMFS of 33.9%. Group comparison showed that 43 target lesions in the group receiving ≤67.2 Gy irradiation and 44 in the group receiving >67.2 Gy irradiation. The 6-month LC, OS, PFS, and DMFS rates between two groups were 89.8% vs. 97.7% ( P=0.127), 89.8% vs. 95.4% ( P=0.305), 65.4% vs. 68.5% ( P=0.514), 65.4% vs. 68.5% ( P=0.516), respectively. The 1-year LC, OS, PFS, and DMFS rates between two groups were 54.1% vs. 89.5% ( P=0.003), 67.3% vs. 82.9% ( P=0.219), 19.2% vs. 32.7% ( P=0.370) and 23.3% vs. 33.0% ( P=0.533). During the follow-up, only 2 patients (3.2%) were found to have grade 1-2 radiation-induced brain injury (asymptomatic brain injury) by MRI examination, and there were no other radiotherapy related adverse reactions. Conclusions:CyberKnife therapy is clinically effective for brain metastases, with mild adverse reactions. Increasing the tumor irradiation dose can improve local tumor control and is expected to further improve the OS of patients.

Proton arc therapy (PAT), as an emerging radiation therapy technique, has attracted increasing widespread attention in the field of cancer radiotherapy in recent years. In this review, technological developments, clinical application potential, biological effects, dosimetric optimization, and current challenges of PAT were comprehensively summarized. A systematic analysis of recent studies indicates that PAT offers significant advantages in improving target coverage and sparing normal tissues, particularly in mitigating organ motion-induced uncertainties. However, PAT remains in the clinical validation stage and still faces challenges related to technical optimization and cost control. Further clinical studies are required to confirm its long-term efficacy and safety.

The global incidence of head and neck cancer (HNC) is rising, with over 60% of patients presenting at a locally advanced stage. Radiotherapy remains a cornerstone of HNC treatment, and advancements in modern techniques and concurrent chemotherapy have improved local control and survival rates of HNC patients. However, these benefits also bring challenges in the management of toxicities. Due to the proximity of salivary glands and tumors, especially the highly radiosensitive parotid and submandibular glands, this condition is among the most common adverse effects of radiotherapy. Radiation damages acinar cells and ducts, causing glandular atrophy, fibrosis, and reduced saliva secretion, thereby leading to xerostomia and related complications. The risk and severity of injury are associated with the radiation dose and volume affecting the glands. Prevention and management strategies emphasize precise radiotherapy planning, target optimization, and supportive care. Emerging multimodal imaging techniques offer potential for non-invasive prediction and early diagnosis and treatment of radiation-induced salivary gland injury. Future research in regenerative medicine, tissue engineering, and molecular biology aims to elucidate molecular mechanisms, such as signaling pathways and genomics, facilitating personalized strategies to mitigate radiotherapy-induced toxicities and enhance the quality of life of patients.

Objective To fabricate wall-less vascular tissue mimicking materials(TMM)with different tube diameters that match the hemodynamic parameters of human carotid arteries,and to investigate their hemodynamic characteristics.Methods TMM with different diameters and blood mimicking fluids containing scattering particles were fabricated.The variation laws of hemodynamic parameters under different flow velocities and TMM phantom diameters were verified.Key hemodynamic parameters including peak systolic velocity(PSV),end-diastolic velocity(EDV),and resistance index were measured using Doppler ultrasound,and their clinical application value in carotid artery diseases was evaluated.Results The fabricated samples exhibited a sound velocity of(1506.2±0.1)m/s and an attenuation of(0.76±0.01)dB/cm,and the vascular diameters were 4.0 and 6.0 mm,which corresponded to the normal clinical range of the external and internal carotid arteries,respectively.For the 4.0 mm TMM,both PSV and EDV were linearly correlated with flow velocity(R2=0.77,P<0.001;R2=0.74,P=0.001),and Pearson correlation analysis confirmed strong positive correlations(r=0.89,95%CI:0.82-0.93;r=0.94,95%CI:0.90-0.97,all P<0.001).For the 6.0 mm TMM,PSV and EDV also demonstrated significant linear correlations with flow velocity(R2=0.70,P=0.001;R2=0.61,P=0.005),with Pearson correlation analysis revealing strong positive correlations(r=0.86,95%CI:0.78-0.91;r=0.79,95%CI:0.68-0.87).All the data were consistent with hemodynamic parameters and followed the variation law of hemodynamic parameters.Conclusion The fabricated TMM and blood mimicking fluids meet the requirements for clinical ultrasound research on hemodynamics,and their material ratios can be used as a reference for the subsequent researches with diverse objectives.

Objective:To explore the feasibility of automatic target volume tracing in the Elekta Unity magnetic resonance imaging (MRI)-guided radiotherapy system and to further enhance the real-time target volume tracing performance of MRI-guided radiotherapy by introducing the deep learning technology based on a large Transformer model.Methods:A total of 4 661 frames of cine MRI binary images from 75 patients with malignant tumors in the chest/abdomen who were treated with MRI-guided radiotherapy were retrospectively collected as a training set. Another 500 frames of cine MRI binary images from 10 patients were collected as an independent test set. A module for medical image format conversion was developed to convert binary images into medical meta-images. The outer contours of tumor target volumes in the cine MRI images of the test set were manually delineated as actual control labels. With the first frame of the cine MRI images of each patient as the reference image and the other frames as motion images, a Transformer-based deep learning model was constructed to describe the deformable vector field (DVF) of motion images relative to the reference image. The Dice similarity coefficient (DSC), the 95% Hausdorff distance (HD 95), the negative Jacobian determinant (NegJ), and the average processing time per frame of cine MRI images were calculated. These values were compared to those of the conventional B-Spline scheme to quantitatively assess the target volume tracing accuracy, DVF physical plausibility, and execution efficiency of the Transformer-based deep learning model. Results:The Transformer-based deep learning model constructed in this study delivered superior target volume tracing performance, with improved DSC [(0.84 ± 0.05) vs. (0.74 ± 0.16), t = 11.44, P < 0.05] and HD 95 [(9.25 ± 2.98) vs. (14.70 ± 8.55) mm, t = -11.83, P < 0.05]. Furthermore, this model reduced the average image processing time from 1.95 s to 30.99 ms, enhancing the efficiency by two orders of magnitude. Besides, this model yielded NegJ similar to that of the B-Spline scheme. This suggests that the DVF extracted using this model had comparable physical plausibility with that obtained using the B-Spline scheme. Conclusions:The Transformer-based deep learning model for automatic target volume tracing fills the functional gap of the Elekta Unity MRI-guided radiotherapy system, facilitating relatively accurate, efficient automatic tracing of moving tumor targets in the chest and abdomen.

Objective To fabricate wall-less vascular tissue mimicking materials(TMM)with different tube diameters that match the hemodynamic parameters of human carotid arteries,and to investigate their hemodynamic characteristics.Methods TMM with different diameters and blood mimicking fluids containing scattering particles were fabricated.The variation laws of hemodynamic parameters under different flow velocities and TMM phantom diameters were verified.Key hemodynamic parameters including peak systolic velocity(PSV),end-diastolic velocity(EDV),and resistance index were measured using Doppler ultrasound,and their clinical application value in carotid artery diseases was evaluated.Results The fabricated samples exhibited a sound velocity of(1506.2±0.1)m/s and an attenuation of(0.76±0.01)dB/cm,and the vascular diameters were 4.0 and 6.0 mm,which corresponded to the normal clinical range of the external and internal carotid arteries,respectively.For the 4.0 mm TMM,both PSV and EDV were linearly correlated with flow velocity(R2=0.77,P<0.001;R2=0.74,P=0.001),and Pearson correlation analysis confirmed strong positive correlations(r=0.89,95%CI:0.82-0.93;r=0.94,95%CI:0.90-0.97,all P<0.001).For the 6.0 mm TMM,PSV and EDV also demonstrated significant linear correlations with flow velocity(R2=0.70,P=0.001;R2=0.61,P=0.005),with Pearson correlation analysis revealing strong positive correlations(r=0.86,95%CI:0.78-0.91;r=0.79,95%CI:0.68-0.87).All the data were consistent with hemodynamic parameters and followed the variation law of hemodynamic parameters.Conclusion The fabricated TMM and blood mimicking fluids meet the requirements for clinical ultrasound research on hemodynamics,and their material ratios can be used as a reference for the subsequent researches with diverse objectives.

Objective:By comparing the effects of installing 3d-printed bolus with or without positioning holes on the skin fit and patient dose distribution,the advantages and disadvantages of the two installation methods in the application of radiotherapy after radical breast cancer surgery were evaluated,and the reference was provided for clinical application.Methods:A total of 48 patients(34 patients with and 14 patients without positioning holes)who received radiotherapy for breast cancer in Suining Central Hospital from December 2022 to Au-gust 2024 were randomly selected.Three dimensional reconstruction of the air gap between the patient body surface and the 3d-printed bolus was conducted,and the tissue dose distribution of each case was analyzed.Comparative analysis was conducted using t-test to ana-lyze the differences of the skin fit and the key dosimetric indexes of target areas and organs at risk between the two bolus installation meth-ods.Results:The mean values of the maximum air gap height,air gap area and air gap volume of the group with positioning holes were lower than those of the group without positioning holes(P<0.05),and the skin fit showed better consistency.The target area conformity in-dex(CI),homogeneity index(HI),and affected lung radiation acceptance(V20,V5)of patients with positioning holes were better than those of patients without positioning holes(P<0.05).There was no significant difference in target area coverage of prescription dose,cardiac dose Dmean and spinal cord dose Dmax between two groups(P>0.05).Conclusions:The skin fit,dosimetric indexes of patient target area and or-gans at risk of 3d-printed bolus with positioning holes were superior to those without positioning holes,showing significant advantages in clinical applications.