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    08 July 2025, Volume 52 Issue 7 Previous Issue   
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    Original Article
    Feasibility study of using dual-energy CT virtual non-contrast images to replace true non-contrast images in photon and proton radiotherapy dose calculations
    Liu Qi, Qu Guobin, Zhu Jian, Wu Fan
    2025, 52 (7):  401-408.  doi: 10.3760/cma.j.cn371439-20250123-00070
    Abstract ( 25 )   HTML ( 6 )   PDF (3765KB) ( 5 )   Save

    Objective To systematically evaluate the differences in CT values between virtual non-contrast (VNC) images and true non-contrast (TNC) images generated from dual-energy CT (DECT),and to validate the feasibility of VNC images replacing TNC images in dose calculations for photon and proton radiotherapy plans. Methods A retrospective analysis was conducted on the imaging data of 40 patients with solid tumors (20 cranial,10 thoracic and 10 abdominal cases) who underwent DECT scans at Cancer Hospital of Shandong First Medical University from February 2022 to May 2023. VNC and TNC images were registered slice-by-slice. The differences in CT values of anatomical structures were compared,and Pearson correlation analysis was used to evaluate the correlation of CT values of different anatomical structures in VNC and TNC images. For structures with significant differences,linear regression models (TNC=β×VNC+α) were established using the least squares method. In the Varian Eclipse 15.5 treatment planning system,photon and proton radiotherapy plans based on TNC images and VNC images,as well as the proton radiotherapy plan based on the VNC images corrected by the regression models,were respectively designed. Dose differences of radiotherapy plans designed based on the two images were evaluated. To evaluate dose variations in regions adjacent to the clinical target volume (CTV),two 2-mm-thick annular reference structures were generated on the axial slice containing the largest cross-section of the CTV,extending cranially and caudally from the CTV. These structures were designated as Ring_p and Ring_d,respectively. Results The differences in CT values between VNC and TNC images were mainly concentrated in the bony structure. The CT values difference between TNC and VNC images was (409.07±53.38) HU for the skull in 20 cranial tumor patients (t=13.88,P<0.001),and (118.66±20.90) HU for the vertebral bone in 10 thoracic and 10 abdominal tumor patients (t=10.43,P<0.001). The CT values of the skull and spine showed high correlation between TNC and VNC images (r=0.98,P<0.001; r=0.99,P<0.001). The regression models established respectively were: TNC=1.859×VNC+33.896 (skull),and TNC=1.827×VNC+5.491 (spine). For photon radiotherapy plans based on TNC and VNC images,the Dmean of the CTV were (60.00±0.00) and (60.00±0.00) Gy respectively,with Dmean of Ring_p were (61.17±1.69) and (61.01±1.67) Gy,and Ring_d were (55.26±2.06) and (55.20±1.94) Gy,respectively. The relative dose differences in Dmean between the two image types were 0 (t<0.01,P>0.999),0.33% (t=0.30,P=0.766),and 0.19% (t=0.07,P=0.947),all with no statistically significant differences. For proton radiotherapy plans based on TNC and VNC images,the Dmean of the CTV were (61.73±0.32) and (61.67±0.26) Gy(RBE),respectively,with Dmean of Ring_p were (61.19±0.44) and (60.53±1.22) Gy(RBE),and Ring_d were (60.97±0.67) and (59.80±4.26) Gy(RBE),respectively. The relative dose differences in Dmean between the two image types were 0.24% (t=0.63,P=0.530),1.80% (t=1.45,P=0.156),and 3.56% (t=2.26,P=0.030),with a statistically significant difference in the Ring_d region. In the proton radiotherapy plan designed based on the corrected VNC images,the Dmean of the CTV was (61.75±0.32) Gy(RBE),Ring_p was (61.43±0.71) Gy(RBE),and Ring_d was (59.96±2.80) Gy(RBE). The relative dose differences in Dmean between TNC images and corrected VNC images were 0.16% (t=0.19,P=0.850),0.76% (t=1.32,P=0.196),and 2.22% (t=1.93,P=0.061),respectively,with no statistically significant differences. Conclusions The differences in CT values between VNC and TNC images in DECT mainly exist in bony structures,particularly in the skull and vertebrae. For patients with cranial tumors,VNC images can be directly used in photon radiotherapy planning. In contrast,for proton therapy,after being corrected by the regression model,VNC images can effectively replace TNC images for the dose calculations of radiotherapy plan.

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    Clinical value of metabolomics in assessing the malignant risk of pulmonary nodules
    Li Xiaoxuan, Xia Zhipeng, Luan Rumei, Wan Yunyan, Yao Zhouhong, Lin Xinshan, Lin Dianjie
    2025, 52 (7):  409-413.  doi: 10.3760/cma.j.cn371439-20241231-00071
    Abstract ( 16 )   HTML ( 5 )   PDF (1192KB) ( 1 )   Save

    Objective To evaluate the diagnostic value of non-targeted detection of metabolic fingerprinting in pulmonary nodules and to analyze the clinical effective model of multi-omics for assessing the malignant risk of pulmonary nodules. Methods A total of 73 patients who underwent chest CT and completed pathological diagnosis and non-targeted detection of metabolic fingerprinting at Shandong Provincial Hospital Affiliated to Shandong First Medical University from November 2021 to October 2024 were selected as the research subjects. According to the postoperative histopathological diagnosis,the patients were divided into the lung malignant nodule group (61 cases) and the lung benign nodule group (12 cases). General clinical data of the patients,including sex,age,smoking history,and family history of tumors,as well as imaging data,including nodule density,nodule size,nodule location,nodule number,and special imaging manifestations (spiculation,lobulation,vacuole sign,vascular convergence sign,etc.),and non-targeted detection of metabolic fingerprinting results were collected. The above data were compared between the two groups of patients,and the receiver operator characteristic (ROC) curve was drawn to evaluate the predictive value of each model. Results There were statistically significant differences in age (t=4.41,P<0.001),nodule size (Z=2.67,P=0.008),nodule density (χ2=4.64,P=0.031),and spiculation (χ2=7.67,P=0.006) between the lung malignant nodule group and the lung benign nodule group. There were no statistically significant differences in sex,smoking history,family history of lung cancer,nodule number,nodule location,lobulation,vacuole sign,vascular convergence sign,pleural indentation sign,calcification sign,bronchial truncation sign,vascular supply sign,and bronchial air sign (all P>0.05). The number of non-targeted detection of metabolic fingerprinting high-risk patients in the lung malignant nodule group (36 cases) was significantly higher than that in the lung benign nodule group (0 case)(χ2=13.97,P<0.001). ROC curve analysis showed that the area under the curve of the Brock model combined with non-targeted detection of metabolic fingerprinting was 0.930 (95%CI: 0.872-0.988),which was greater than that of the Brock model (0.856,95%CI: 0.769-0.942,Z=0.27,P=0.040) and non-targeted detection of metabolic fingerprinting (0.768,95%CI: 0.650-0.887,Z=0.30,P=0.004) alone. Conclusions Non-targeted detection of metabolic fingerprinting risk assessment may serve as a non-invasive method to assist the Brock model in the diagnosis of pulmonary nodules and has good application value. The combination of the Brock model and non-targeted detection of metabolic fingerprinting can more accurately distinguish the benign and malignant nature of pulmonary nodules.

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    Exploration of the predictive value of high-resolution CT imaging features combined with Ki-67 expression for poorly differentiated invasive non-mucinous lung adenocarcinoma
    Zhang Bei, Huo Awei, Kang Tong, Yang Bo
    2025, 52 (7):  414-418.  doi: 10.3760/cma.j.cn371439-20240607-00072
    Abstract ( 14 )   HTML ( 3 )   PDF (994KB) ( 2 )   Save

    Objective To investigate the predictive value of high-resolution CT (HRCT) imaging features and Ki-67 expression levels for poorly differentiated invasive non-mucinous lung adenocarcinoma (INMA),and to construct and validate a nomogram prediction model based on these factors. Methods A total of 210 INMA patients who underwent radical surgery at Shaanxi Provincial Cancer Hospital from July 2020 to October 2023 and obtained histopathological results were retrospectively included. Based on the degree of lesion differentiation,they were divided into well/moderately differentiated INMA group (n=152) and poorly differentiated INMA group (n=58). The general clinical data,HRCT imaging features and Ki-67 expression of the two groups of patients were compared. Multivariate logistic regression analysis was used to analyze independent influencing factors for poorly differentiated INMA,and a nomogram prediction model was constructed. The diagnostic efficacy of the prediction model was evaluated by the receiver operator characteristic (ROC) curve,and the prediction model was validated by consistency index (C-index) and calibration curve. Results There were no statistically significant differences in terms of age,location,margin,lobulation,vascular convergence,and cavitation between the well/moderately differentiated INMA group and poorly differentiated INMA group (all P>0.05). There were statistically significant differences in sex (χ2=6.65,P=0.010),Ki-67 expression (U=2.33,P=0.021),nodule size (t=-3.34,P=0.010),spiculation (χ2=5.22,P=0.022),pleural indentation (χ2=17.02,P<0.001),air bronchogram (χ2=15.54,P<0.001) and nodule type (χ2=59.67,P<0.001) between the two groups. Multivariate analysis showed that nodule size (OR=1.07,95%CI: 1.01-1.14,P=0.025),nodule type (OR=8.23,95%CI: 3.04-22.32,P<0.001) and Ki-67 expression (OR=1.07,95%CI: 1.03-1.11,P<0.001) were independent influencing factors for the occurrence of poorly differentiated INMA. A nomogram prediction model for poorly differentiated INMA was constructed based on the above indicators. ROC curve analysis showed that the area under curve of the prediction model to predict the occurrence of poorly differentiated INMA was 0.893,and the sensitivity and specificity were 89.70% and 77.60%,respectively. The C-index value of the model was 0.893. The calibration curve showed that the predicted probability was in good agreement with the actual probability. Conclusions Nodule size,nodule type in HRCT imaging features and Ki-67 expression are independent influencing factors for the occurrence of low differentiation in INMA patients. The nomogram prediction model constructed based on the above indicators has good predictive performance.

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    A real-world study on efficacy of different second-line treatment strategies following the progression of first-line immunotherapy and its combination therapies in driver gene-negative advanced non-small cell lung cancer
    Zhang Luying, Liang Jiaxin, Zhao Kelei, Yuan Xiaohan, Liu Liangbo, Lu Ping, Zhang Guifang, Zhang Min
    2025, 52 (7):  419-425.  doi: 10.3760/cma.j.cn371439-20241030-00073
    Abstract ( 16 )   HTML ( 4 )   PDF (1628KB) ( 5 )   Save

    Objective To explore the efficacy of different second-line treatment strategies in the real world after progression of first-line immunotherapy and its combination therapies in patients with driver gene-negative advanced non-small cell lung cancer (NSCLC). Methods A retrospective analysis was conducted on the clinical data of 93 driver gene-negative advanced NSCLC patients who received first-line immunotherapy and its combination therapies from January 1,2018 to December 31,2023 at the First Affiliated Hospital of Xinxiang Medical University and Xinxiang Central Hospital. Patients were categorized into immune checkpoint inhibitors (ICIs)-resistant (n=43) and ICIs-responsive (n=50) groups according to whether progression free survival (PFS) exceeded 6 months after first-line treatment. Patients were categorized into ICIs-treated (n=55) and non-ICIs-treated (n=38),anti-angiogenic-treated (n=51) and non-anti-angiogenic-treated (n=42) groups according to the different second-line treatment strategies after progression of first-line immunotherapy and its combination therapies. The median PFS2 (mPFS2) and median overall survival (mOS)2 after second-line treatment of each group were compared. The Kaplan-Meier method was used for survival analysis. Results The mPFS2 and mOS2 of 93 advanced NSCLC patients who progressed after first-line ICIs treatment were 4.9 months (95%CI: 4.1-5.7 months) and 14.7 months (95%CI: 11.2-18.2 months). The mPFS2 of patients in the first-line ICIs-responsive and ICIs-resistant groups were 6.0 and 3.8 months,respectively,with no statistically significant difference (χ2=2.00,P=0.157),and the mOS2 were 25.3 and 11.3 months,respectively,with a statistically significant difference (χ2=12.13,P<0.001). The mPFS2 of patients in the second-line ICIs-treated group and the non-ICIs-treated group were 5.2 and 4.6 months,respectively,with no statistically significant difference (χ2=0.16,P=0.687). The mOS2 were 15.1 and 12.7 months,respectively,with no statistically significant difference (χ2=0.01,P=0.930). The mPFS2 of patients in the second-line anti-angiogenic-treated and non-anti-angiogenic-treated groups were 4.5 and 6.0 months,respectively,with no statistically significant difference (χ2=0.41,P=0.525),the mOS2 were 14.7 and 16.8 months,respectively,with no statistically significant difference (χ2=0.01,P=0.943). Conclusions After progression of first-line ICIs therapy in patients with driver gene-negative advanced NSCLC,first-line ICIs-responsive patients have significantly longer OS after second-line treatment compared with ICIs-resistant patients. The efficacy of second-line therapy in patients after progression of first-line ICIs therapy does not show significant differences due to the type of treatment strategies.

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    Predictive value of T cell subtype characteristics and peripheral blood inflammatory indicators in patients with liver cancer for myelosuppression after hepatic artery infusion chemotherapy
    Zhang Rongrong, Liu Yanming, Chen Xiangyan, Ling Jing
    2025, 52 (7):  426-431.  doi: 10.3760/cma.j.cn371439-20241009-00074
    Abstract ( 11 )   HTML ( 3 )   PDF (897KB) ( 1 )   Save

    Objective To explore the predictive value of T cell subtype characteristics and peripheral blood inflammatory indicators in patients with liver cancer for myelosuppression after hepatic artery infusion chemotherapy. Methods A total of 115 patients with primary hepatocellular carcinoma who received transcatheter arterial chemoembolization (TACE) treatment in the Department of Oncology of Taizhou Jiangyan Traditional Chinese Medicine Hospital from May 2022 to May 2024 were enrolled as the research subjects. According to whether myelosuppression occurred after TACE treatment,the patients were divided into a non-myelosuppression group (n=93) and a myelosuppression group (n=22). The clinical data,the proportions of T cell subsets before TACE treatment,and the differences in the levels of peripheral blood inflammatory indexes were compared between the two groups. Spearman correlation analysis and multivariate logistic regression analysis were used to screen out the influencing factors of myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma. The receiver operator characteristic (ROC) curve was used to analyze the efficacy of each influencing factor in predicting the myelosuppression of patients. Results There were no statistically significant differences in age,sex,history of hypertension,body mass index,type of hepatitis virus infection,status of hypersplenism,Barcelona staging,Child-Pugh classification of liver function,number of TACE treatments,and the proportion of CD8+ T cells between the patients in the myelosuppression group and non-myelosuppression group (all P>0.05). However,there were statistically significant differences in diabetes (χ2=3.94,P=0.047),history of alcohol consumption (χ2=5.47,P=0.019),the longest diameter of the tumor (Z=2.31,P=0.021),the presence of ascites (χ2=4.10,P=0.043),the proportion of CD4+ T cells (t=4.66,P<0.001),the ratio of CD4+/CD8+t=4.98,P<0.001),the neutrophil/lymphocyte ratio (NLR)(t=4.98,P<0.001),the monocyte/lymphocyte ratio (MLR)(t=2.31,P=0.023),and the systemic immune inflammation index (SII)(t=5.31,P<0.001). Spearman correlation analysis showed that diabetes (r=0.19,P=0.048),history of alcohol consumption (r=0.22,P=0.019),the presence of ascites (r=0.19,P=0.043),the longest diameter of the tumor (r=0.22,P=0.020),NLR (r=0.39,P<0.001),MLR (r=0.30,P=0.001),and SII (r=0.36,P<0.001) were all positively correlated with myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma,while the proportion of CD4+ T cells (r=-0.37,P<0.001) and the ratio of CD4+/CD8+r=-0.40,P<0.001) were negatively correlated with myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma. Multivariate logistic regression analysis showed that the ratio of CD4+/CD8+OR=0.01,95%CI: 0.01-0.11,P=0.002) was an independent protective factor for myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma,and NLR (OR=1.82,95%CI: 1.31-5.60,P=0.013) and SII (OR=1.03,95%CI: 1.01-1.05,P=0.002) were both independent risk factors for myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma. ROC curve analysis showed that the areas under the curve (AUCs) of the ratio of CD4+/CD8+,NLR,and SII for predicting myelosuppression after TACE treatment in patients with primary hepatocellular carcinoma alone were 0.79 (95%CI: 0.70-0.89),0.78 (95%CI: 0.65-0.92),and 0.76 (95%CI: 0.65-0.87),respectively. The AUC of the combined prediction of the three was 0.91 (95%CI: 0.83-0.99),which was higher than that of the ratio of CD4+/CD8+Z=4.21,P<0.001),NLR (Z=4.36,P<0.001),and SII (Z=4.48,P<0.001) for prediction alone. Conclusions The ratio of CD4+/CD8+,as well as NLR and SII levels before TACE treatment are independent factors influencing the occurrence of myelosuppression after treatment in patients with primary hepatocellular carcinoma,and are expected to be important indicators for predicting myelosuppression after hepatic artery infusion chemotherapy in patients with primary hepatocellular carcinoma.

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    Dosimetric characteristics of proton radiotherapy
    Preface to the dosimetric characteristic of proton radiotherapy for tumors
    Zhu Jian
    2025, 52 (7):  432-433.  doi: 10.3760/cma.j.cn371439-20250217-00075
    Abstract ( 12 )   HTML ( 4 )   PDF (706KB) ( 2 )   Save

    Proton beam have been widely used in the field of tumor radiotherapy due to the significant physical dosimetric advantages. This series of studies enrolled typical tumor target areas,including the head and neck,whole central nervous system,lungs,esophagus,breast,abdominal and pelvic cavities,and developed both proton and photon radiotherapy plans to compare and evaluate the dosimetric characteristics provided by the two techniques. These studies aim to reflect the dosimetric differences between proton and photon radiotherapy,thus providing references for doctors' clinical decision-making and patients' medical choices.

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    Analysis of dosimetric characteristics of proton radiotherapy in 1 case of whole central nervous system tumor
    Wu Shizhang, Hu Man, Dai Tianyuan, Li Chengqiang, Tao Cheng, Duan Jinghao, Chen Jinhu, Bai Tong, Kong Tian, Zhu Jian
    2025, 52 (7):  434-440.  doi: 10.3760/cma.j.cn371439-20250217-00076
    Abstract ( 13 )   HTML ( 3 )   PDF (6015KB) ( 0 )   Save

    Objective To explore the dosimetric characteristics of intensity modulated proton therapy (IMPT),intensity modulated radiation therapy (IMRT) and tomotherapy (TOMO) techniques applied in the irradiation of pediatric whole central nervous system tumors. Methods Taking the target area of a 14-year-old pediatric patient clinically diagnosed with atypical teratoid/rhabdomyoid tumor,meningeal metastasis by Shandong Cancer Hospital and Institute,and undergoing craniospinal irradiation (CSI) as an example,IMPT,IMRT and TOMO plans were designed respectively based on the clinical prescription of the target area and the limit requirements of organs at risk (OARs). The conformal index (CI),homogeneity index (HI) and gradient index (GI) of each planning target volume,as well as the dose volume index of normal tissues,were evaluated to compare the dosimetric characteristics of the three types of plans. Results The CI (0.71),HI (0.05) and GI (3.13) of the IMPT plan were comparable to those of IMRT plan (0.80,0.08,3.14). The HI (0.03) and GI (2.54) of the TOMO plan were excellent,which were all within the clinically acceptable range. The irradiation dose to parallel organs in the IMPT plan was lower than that in the IMRT and TOMO plan. In the IMPT plan,V5 of lungs was 2.9%,IMRT plan was 37.6%,and TOMO plan was 43.5%. The Dmean of liver in the IMPT plan was 0.01 Gy(RBE),IMRT plan was 6.12 Gy,and TOMO plan was 6.39 Gy. In the IMPT plan,none of the bladder,rectum,and femoral head received the dose,while there was low-dose radiation in both IMRT and TOMO plan. For serial organs adjacent to and within the target area,the Dmax of spinal cord and brainstem in IMPT plan was 39.89 and 39.88 Gy(RBE),respectively; in IMRT plan,they were 39.43 and 38.59 Gy,respectively; and in TOMO plan,they were 38.41 and 37.69 Gy,respectively. The low-dose area in the IMPT plan was significantly better than the photon radiotherapy plans. Among them,the absolute volume IMPT plan occupied by 10% of the prescribed dose area in the patient's body was reduced by 70.10% compared with IMRT plan and 76.96% compared with TOMO plan; the 30% prescribed dose volume IMPT plan was reduced by 53.49% compared with IMRT plan and 62.51% compared with TOMO plan; the 50% prescribed dose volume IMPT plan was reduced by 39.06% compared with IMRT plan and 42.23% compared with TOMO plan. Conclusions The IMPT plan demonstrated significantly reduced low-dose exposure and lower doses to parallel OARs compared to both IMRT and TOMO plans in pediatric CSI. The CI,HI and GI of the three plans can all meet the clinical requirements. However,for serial organs adjacent to and within the target area,the Dmax of the IMPT plan may be higher than that of IMRT and TOMO plans.

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    Correlation study of spectral CT parameters and MRI ADC changes in proton radiotherapy for chordoma
    Xu Jian, Duan Jinghao, Liu Qingzeng, Zhu Jian
    2025, 52 (7):  441-447.  doi: 10.3760/cma.j.cn371439-20250217-00077
    Abstract ( 11 )   HTML ( 4 )   PDF (1912KB) ( 1 )   Save

    Objective To preliminarily explore the correlation between the quantitative parameters of spectral CT before proton radiotherapy and the changes in apparent diffusion coefficient (ADC) of MRI before and after radiotherapy in chordoma patients. Methods A retrospective analysis was conducted on imaging data from 28 patients with chordoma who underwent proton radiotherapy at Shandong Cancer Hospital and Institute from August 2022 to December 2024. Spectral CT images obtained prior to treatment were used to extract four quantitative parameters of the lesion area: relative iodine concentration (RIC),electron density (ED),effective atomic number (Zeff),and the slope of spectral attenuation curve (λHU). In parallel,MRI-DWI scans before and after treatment were collected to compute the ADC difference (ΔADC). The correlation between spectral CT parameters and ΔADC was assessed using scatter plots,simple linear regression,LOWESS curve fitting,correlation matrix,and bootstrap resampling methods. Results The ADC of 28 patients was 1 137.05 (921.07,1 643.91) before treatment,and 1 197.10 (994.75,1 785.57) after treatment,and the ΔADC was 133.18 (-36.46,253.04). The RIC was 0.45 (0.12,0.67),the ED was 38.01±12.72,the Zeff was 8.40±0.64,and the λHU was -2.20±1.05. The scatter plots results indicated a positive distribution trend between RIC and ΔADC,and a negative trend between λHu and ΔADC. Simple linear regression showed that RIC had the highest goodness of fit with ΔADC (R²=0.75) and the largest regression coefficient (β=518.34),followed by λHU (R²=0.64,β=-121.94). The goodness of fit between Zeff and ΔADC was low (R²=0.25). No correlation was found between ED and ΔADC. LOWESS curve fitting showed a consistent trend with simple linear regression results,without significant deviation. The correlation matrix indicated that RIC was positively correlated with ΔADC (r=0.88,P<0.001),Zeff was moderately positively correlated with ΔADC (r=0.51,P=0.006),and λHU was negatively correlated with ΔADC (r=-0.84,P<0.001). Bootstrap resampling analysis showed that the r values of RIC,Zeff,λHU and ΔADC were 0.87,0.50,-0.80,respectively. Conclusions The spectral CT parameter RIC of chordoma patients before proton radiotherapy is positively correlated with ΔADC,while λHU exhibits a negative correlation with ΔADC.

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    Analysis of dosimetric characteristics of proton radiotherapy in 4 cases of breast cancer
    Li Chengqiang, Wang Yungang, Yu Yishan, Wu Shizhang, Tao Cheng, Ma Xingmin, Dai Tianyuan, Duan Jinghao, Chen Jinhu, Bai Tong, Zhu Jian
    2025, 52 (7):  448-454.  doi: 10.3760/cma.j.cn371439-20250217-00078
    Abstract ( 10 )   HTML ( 4 )   PDF (5068KB) ( 1 )   Save

    Objective To explore the dosimetric characteristics of proton and photon radiotherapy in the treatment of breast cancer. Methods Four female breast cancer patients who needed radiotherapy at Shandong Cancer Hospital and Institute from January 2024 to May 2024 were selected as the research subjects. The target area ranges of 4 patients were left-sided breast cancer with lymph node involvement,left-sided breast cancer with lymph node involvement and internal mammary node,right-sided breast cancer with lymph node involvement and internal mammary node and synchronous bilateral breast cancer. Intensity modulated proton therapy (IMPT) and intensity modulated radiation therapy (IMRT) plans were designed respectively based on the prescribed dose in the target area and the limits of organs at risk (tomotherapy plan for bilateral breasts). The conformity index (CI),homogeneity index (HI),gradient index (GI) and organs at risk doses were evaluated. The dosimetric characteristics of IMPT and photon radiotherapy were compared. Results Both IMPT and photon radiotherapy plans of the 4 breast cancer cases met the clinical dose requirements. The HI value of IMPT plans (0.10-0.14) was comparable to that of photon radiotherapy plans (0.10-0.12),and the average CI of the photon radiotherapy plans was 0.10 higher than that of the IMPT plans,and the average GI was 0.55 lower than that of the IMPT plans. The Dmean of ipsilateral lung and heart of IMPT was lower,especially in the low-dose area (V0-3),which was significantly lower than the photon radiotherapy plans,Dmean of ipsilateral lung was reduced by 12.2%,6.1%,16.1% and 34.8%,respectively,Dmean of heart was reduced by 47.2%,57.0%,72.4% and 83.0%,respectively. The ipsilateral lung V20 of IMPT was not lower than photon radiotherapy plans (unilateral breast: IMPT was 30.0%-34.0%,IMRT was 29.0%-35.9%). Conclusions IMPT significantly reduces the Dmean to the ipsilateral lung and heart while ensuring dose coverage of the target in breast cancer,preventing more volume of surrounding normal tissues from being irradiated. However,IMPT does not show much more advantage than photon radiotherapy plans in the ipsilateral lung V20.

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    Analysis of dosimetric characteristics of proton radiotherapy in 3 cases of abdominal and pelvic tumors
    Duan Jinghao, Yue Jinbo, Tao Cheng, Wu Shizhang, Li Chengqiang, Dai Tianyuan, Chen Jinhu, Bai Tong, Zhu Jian
    2025, 52 (7):  455-461.  doi: 10.3760/cma.j.cn371439-20250217-00079
    Abstract ( 11 )   HTML ( 3 )   PDF (5778KB) ( 1 )   Save

    Objective To explore the dosimetric characteristics of intensity modulated proton therapy (IMPT) and intensity modulated radiation therapy (IMRT) for typical abdominal and pelvic tumors. Methods Three patients with abdominal and pelvic tumors (one case each of liver cancer,cervical cancer,and prostate cancer) admitted to Shandong Cancer Hospital and Institute from January to June 2024 were selected as the research subjects. IMPT and IMRT plans were designed for each case based on clinical target volume (CTV) and organs at risk (OARs) constraints. Dosimetric parameters,including conformity index (CI),homogeneity index (HI),and gradient index (GI) for target coverage,as well as OARs dose metrics,were evaluated. The volume of additional dose deposition in the body was compared by assessing regions receiving 10%,30%,and 50% of the prescription dose. Results For all three cases,IMRT plan demonstrated higher CI values (0.82,0.81,and 0.86) compared to IMPT plan (0.61,0.62,and 0.43). IMPT plan yielded lower HI values (0.053,0.075,and 0.020) than IMRT plan (0.060,0.120,and 0.080) and lower GI values (3.45,2.63,and 3.80 vs. 7.28,4.76,and 4.66 for IMRT plan). In liver cancer,IMPT plan reduced the Dmean of normal liver tissues and right kidney by 37.8% and 78.5%,respectively,and decreased the Dmax of spinal cord by 13.2%. For cervical cancer,IMPT plan reduced the V30 of the small bowel by 22.0%,Dmean of the bladder,rectum and bone marrow by 15.7%,14.3% and 12.6%,and spinal cord Dmax by 4.8%. In prostate cancer,IMPT plan lowered bladder and rectal Dmean by 14.9% and 36.5%,respectively,but resulted in an increase of 35.3% and 6.1% in the Dmean and V40 of the left femoral head,respectively,and an increase of 23.6% and 10.8% in the Dmean and V40 of the right femoral head,respectively. IMPT plan reduced the volumes receiving 10%,30%,and 50% of the prescription dose by 48.9%-64.8%,22.0%-47.0%,and 22.0%-57.7%,respectively,compared to IMRT plan. Conclusions Comparison between IMPT and IMRT plans for abdominopelvic tumors: IMPT plan offers advantages in reducing doses to normal organs such as the liver,kidneys,spinal cord,small intestine,rectum,and bladder. However,its advantage is less pronounced regarding the dose to the femoral heads. IMPT plan notably minimizes additional dose deposition within the body.

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