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Objective:To investigate the effects of CT images reconstructed using different field of view (FOV) sizes on the automatic segmentation of organs at risk and dose calculation accuracy in radiotherapy after radical mastectomy.Methods:Under the same scanning conditions, CT values-electron density conversion curves were established by reconstructing the original CT images of a phantom placed at the isocenter and extended FOV (eFOV) positions using FOV sizes of 50, 60, 70 and 80 cm. Then, these curves were compared. A standard phantom with a known volume was scanned, and the automatic segmentation result of the phantom on CT images reconstructed using different FOV sizes was compared. A total of 30 patients in Guangdong Second Provincial General Hospital from January 2020 to June 2022 with breast cancer were randomly selected. Through simulated positioning, their CT images were reconstructed using different FOV sizes for the purpose of automatic segmentation of organs at risk, followed by comparison between the outcomes of automatic segmentation and physicians′segmentation. The treatment plan established based on CT images reconstructed using a FOV size of 50 cm (FOV 50 images for short) was applied to CT images reconstructed using FOV sizes of 60, 70 and 80 cm (FOV 60, FOV 70 and FOV 80 images for short) for dose calculation, and the dose calculation result were compared. Results:The CT values - electron density conversion curves derived from CT images reconstructed using different FOV sizes were roughly consistent. At the isocenter, the difference between the segmented volume and actual volume of the standard phantom increased up to a maximum of 6 cm 3 (4.8%) with an increase in the FOV size. As indicated by the automatic segmentation result, the segmentation accuracy of the spinal cord, trachea, esophagus, thyroid, healthy mammary gland, and skin decreased with an increase in the FOV size ( t = -28.43-8.23, P < 0.05). The comparison of dose calculated based on CT images reconstructed using different FOV sizes showed that there was no statistically significant differences( P>0.05) in the dose to target volume ( V95) and the maximum and average doses in the supraclavicular lymph node region, as well as the dose to organs at risk. The coverage for planned target volume decreased with an increase in the FOV size, with a maximum difference of 4.06%. Conclusions:It is recommended that, for radiotherapy after radical mastectomy, FOV 50 images should be selected for the automatic segmentation of organs at risk, CT-values-electron density conversion curves should be established based on the electron density phantom images of the eFOV region, and the eFOV 80 images should be preferred for dose calculation.
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Objective:To evaluate the feasibility of delineating subvolume target in radiotherapy for brain tumors using Gd-based contrast clearance difference.Methods:Twenty-six patients with malignant brain tumors were scanned with MRI. The first and second acquisitions of standard T 2-weighted images (T 2WI) and T 1-weighted images (T 1WI) were performed at 5 min and 60 min after injection of contrast agent. Delayed contrast extravasation (DCEM) MRI computed by Brainlab comprised regions of contrast agent clearance representing active tumors and regions of contrast accumulation representing non-tumor tissues. Based on T 2WI images, 14 patients with liquefaction necrosis were divided into group A, and 12 patients without liquefaction necrosis into group B, respectively. Then, gross target volume (GTV) was delineated on T 1WI images. Based on the GTV, active tumor (GTV tumor) and non-tumor regions (GTV non-tumor) were delineated on T 1WI-DCEM fusion images, while liquefaction necrosis (GTV liquefaction) and non-liquefaction (GTV non-liquefaction) were delineated on T 1-T 2WI fusion images. Finally, the differences between different subvolumes were compared by paired t-test. Results:In group A, the GTV non-liquefaction and GTV liquefaction were (13.65±18.15) cm 3 and (6.30±7.57) cm 3. The GTV tumor was (10.40±13.52) cm 3 and the GTV non-tumor was (9.55±14.57) cm 3. The GTV non-liquefaction was significantly increased by 16.3% on average compared with the GTV tumor ( P<0.05). The GTV non-tumor was significantly increased by 16.3% on average compared with the GTV liquefaction ( P<0.05). In group B, The GTV non-tumor was significantly reduced by 68.8% on average compared with the GTV tumor ( P<0.05). Conclusions:Compared with T 2WI, DCEM has advantages in identifying the liquefaction area and can clearly differentiate the subvolume of active tumors from non-liquefaction necrosis. DCEM provides evidence for guiding the delineation of subvolume in primary and metastatic brain tumors.
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Objective:To evaluate the effect of different reconstruction images on cardiac dose evaluation by comparing the differences between 4D-CT series and special reconstruction images in evaluating the dose-volume index of cardiac structures.Methods:ECG 4D-CT series were scanned in 15 female patients with left breast cancer. The images of 0-95% 20 phases were reconstructed at an interval of 5% cardiac cycle. The maximum intensity projection (MIP), minimum intensity projection (MinIP), average intensity projection (AIP) and sum intensity projection (SIP) images were obtained by special reconstruction of 4D-CT series. Left ventricle (LV) and left anterior descending coronary artery (LADCA) were delineated on 4D-CT and special reconstruction series, respectively. The intensity-modulated radiation therapy plan of the left breast cancer was designed on the basis of 0% phase, and the cumulative dose (Dose-cumulate) of 20 phases was obtained by deformation registration. The doses of 0% phase were deformed and registered to MIP, MinIP, AIP and SIP images to obtain the corresponding dose distribution. The dose-volume indexes of LV and LADCA based on different CT images were compared.Results:In the evaluation of dose-volume index of LV, compared with 4D-CT series, the change rates of V 5Gy, V 30Gy, V 40Gy, D max and D mean on MIP images were 3.8%, 2.0%, 0.9%, 3.8% and 1.7%, respectively. There was significant difference in V 5 and D max between MIP and 4D-CT (both P<0.05). Compared with 4D-CT, the change rates of D max on MinIP, SIP and AIP images were 2.5%, 3.1% and 1.5%, respectively (all P<0.05). In the evaluation of dose-volume index of LADCA, only the change rate of D max on four special reconstructed images was<5%( P<0.05). Conclusions:In the dose-volume evaluation of LV, the V 30Gy, V 40Gy and D mean obtained by MIP are basically equivalent to those obtained by 4D-CT series, which can be used to substitute 4D-CT series to evaluate the dose-volume. The special reconstruction image of LADCA can not replace 4D-CT series.
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Objective:To compare the differences in the delineation of the gross tumor volume (GTV) and lymph nodes of nasopharyngeal carcinoma (NPC) patients using computerized tomography (CT), magnetic resonance imaging (MRI), and 18F-fluorodeoxyglucose positron emission tomography/computed tomography ( 18F-FDG PET/CT), and to investigate the optimal standard uptake value (SUV; relative to the MRI-based delineation) for the automatic delineation of GTV using PET. Methods:A total of 53 NPC patients proposing to receive radiotherapy were selected for this study. The CT, MRI, and PET images of each patient were obtained before radiotherapy. Then GTV and positive lymph nodes were delineated on these three types of images. They were individually named GTV MRI, GTV CT, GTV PET2.5 (SUV=2.5), Lymph MRI, Lymph CT, and Lymph PET2.5 and compared. The GTV ∩2.5 (overlapped GTV) was obtained through the alignment of MRI and PET/CT images. Meanwhile, GTV was delineated on PET images using thresholds of SUV=4.0, 4.5, 5.0, and 5.6, obtaining GTV PET4.0, GTV PET4.5, GTV PET5.0, and GTV PET5.6. Then their volume and Dice similarity coefficients (DSCs) were compared. Results:Compared to GTV MRI, GTV CT decreased by 1.73% ( P>0.05) and GTV PET2.5 increased by 21.34% ( t=-3.52, P < 0.05) in the three types of images. The volume of Lymph PET2.5 was 1.61 and 1.87 times the volume of Lymph MRI and Lymph CT, respectively ( t=-4.12, -5.18; P< 0.05). The volume of high-SUV lymph nodes was 4.07 times the volume of lymph nodes with low SUVs or SUV=0 ( t=5.50, P< 0.05) on PET images. The DSC between GTV PET4.0and GTV MRI was 0.78 ± 0.27, which was lower than that between GTV PET2.5 and GTV MRI (0.84 ± 0.18). However, GTV PET4.0 approximated to GTV ∩2.5 ( P>0.05). Conclusions:Compared to CT and 18F-FDG PET/CT, MRI shows more accurate boundaries of GTV and lymph nodes. When 18F-FDG PET/CT was adopted to automatically delineate GTV, the GTV delineated using SUV=4.0 was closer to GTV MRI.
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Objective:To evaluate the feasibility of magnetic resonance (MR) perfusion imaging for sub-region segmentation of brain metastases (BMs), and to provide reference for individualized radiotherapy based on blood flow perfusion heterogeneity in BMs patients.Methods:96 BMs patients were selected, including 55 patients with necrosis and 41 without necrosis. Each patient was scanned with CT simulation and MR simulation before radiotherapy. MIM Maestro 6.8.8 software was used to delineate the gross tumor volume (GTV) and necrosis GTV (GTV N) from enhanced T 1W images and T 2 Propeller images, respectively, and the solid GTV (GTV S) was obtained by the subtraction of the two. Then, the cerebral blood flow map of three dimensional arterial spin labeling (3D-ASL) was employed to determine the high perfused GTV (GTV H) and low perfused GTV (GTV L). The volume and proportion of sub-regions were counted and compared between two groups and the correlation of each sub-region was analyzed. Results:The volume of GTV in the necrosis and non-necrosis groups was 19.56 and 7.34 cm 3, respectively. Besides, the AUC of the ROC between GTV volume and necrosis was 0.749. In the necrosis group, the ratio of GTV N, GTV S, GTV H and GTV L to GTV was 20.47%, 79.53%, 33.03% and 46.50%, respectively (all P<0.05). Among them, the r value between GTV S and GTV was 0.963, 0.849 for GTV L and GTV, and 0.840 for GTV L and GTV S, significantly higher than 0.683 for GTV H and GTV and 0.764 for GTV H and GTV S (all P<0.05). In the non-necrosis group, the ratio of GTV H to GTV was higher than that in the necrosis group (58.95% vs. 33.03%, P<0.05). In addition, the ratio of GTV L to GTV was slightly lower than that in the necrosis group (41.05% vs. 46.50%, P>0.05). The r value between GTV H and GTV was 0.776, significantly higher than 0.574 between GTV L and GTV ( P<0.05). Conclusion:MR-3D-ASL can quantitatively analyze the heterogeneous blood perfusion of BMs, which could guide the sub-region segmentation and local dose escalation of tumors.
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Objective To study the effects of different CT values assignment methods on the dose calculation of radiotherapy plan for brain metastases,which will provide a reference for radiotherapy treatment planning based on MR images.Methods A total of 35 patients treated with radiotherapy for brain metastases were selected,with pre-treatment CT and MR simulated positioning performed at the same day.Based on the simulation CT images,three dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) plans were calculated as the original plan (Plan1).The CT and MR images were rigidly registered and then the main tissues and organs were delineated on CT and MR images.The average CT values of each tissue and organ were calculated.Three groups of pseudo CT were generated by three CT values assignment methods based on the CT images:whole tissue was assigned 140 HU;cavity,bone and other tissues were assigned-700 HU,700 HU and 20 HU,respectively;different tissues and organs were assigned corresponding CT values.The dose distribution of Plan1 was recalculated on three groups of pseudo-CT to obtain Plan2,Plan3 and Plan4,respectively.Finally,the dosimetric difference between Plan1 and other plans (including Plan2,Plan3 and Plan4) were compared.Results The average CT values of bone and cavity were (735.3 ± 68.0) HU and (-723.9 ± 27.0) HU,respectively.The average CT values of soft tissues was mostly distributed from-70 to 70 HU.The dosimetric differences between Plan2,Plan3,Plan4,and Plan1 decreased in turn.The differences of maximum dose of lens were the biggest,which can reach more than 5.0％,1.5％-2.0％ and 1.0％-1.5％,respectively,and the differences of other dose parameters were basically less than 2.0％,1.2％and 0.8％,respectively.In the pixelwise dosimetric comparison,the areas with more than 1％ difference in the local target cases were mainly distributed in the skin near the field.On the other hand,those in the whole brain target cases were mainly distributed at the bone,cavity,bone and soft tissues junction,and the skin near the field.In addition,the dose calculation error of CT value assignment methods in 3D-CRT plan was slightly larger than that in IMRT plan,and that in whole brain target cases were significantly larger than that in local target cases.Conclusions Different CT value assignment methods have a significant effect on the dose calculation of radiotherapy for brain metastases.When appropriate CT values are given to bone,air cavity and soft tissue,respectively,the deviation of dose calculation can be basically controlled within 1.2％.And by assigning mass CT values to various tissues and organs,the deviation can be further controlled within 0.8％,which can meet the clinical requirements.
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Objective To establish radiomics models based on different CT scaning phases to distinguish mediastinal metastatic lymph nodes in NSCLC and to explore the diagnostic efficacy of these models.Methods The CT images of 86 preoperative patients with NSCLC who were performed both plain and enhanced CT scans were analyzed retrospectively.The 231 mediastinal lymph nodes were enrolled in this study which were divided into two independent cohorts:163 lymph nodes enrolled from January 2015 to June 2017 constituted the training cohort,and 68 lymph nodes enrolled from July 2017 to June 2018 constituted the validation cohort.The regions of interest (ROIs) were delineated on plain scan phase,arterial phase and venous phase CT images respectively,and 841 features were extracted from each ROI.LASSO-logistic regression analysis was used to select features and develop models.The area under the ROC curve (AUC value),sensitivity,specificity,accuracy,positive predictive value and negative predictive value of different models for distinguishing metastatic lymph nodes were compared.Results A total of 6 models were established,and the AUC values were all greater than 0.800.The plain CT model yielded the highest AUC,specificity,accuracy and positive predictive value with 0.926,0.860,0.871,0.906 in the training cohort and 0.925,0.769,0.882,0.870 in the validation cohort.When plain and venous phase CT images were combined with arterial phase CT images,the sensitivity and negative predictive value of the models increased from 0.879,0.821 and 0.919,0.789 to 0.949,0.878 and 0.979,0.900 respectively.Conclusions The CT radiomics model could be used to assist the clinical diagnosis of lymph nodes.The AUC value of the model based on plain scanning was the highest,while the sensitivity and negative predictive value of the model could be improved by combining the arterial phase CT images.
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Objective:To provide a feasible method for the evaluation of cardiac function based on cardiac gated 4DCT, the radiomics technology combined with enhanced ECG gated 4DCT images were used to quantitatively analyze the changes of left ventricular CT radiomics characteristics in cardiac cycle.Methods:The enhanced ECG 4DCT images of 14 patients were reconstructed at intervals of 5% of cardiac cycle. The left ventricular muscle (LVM) and the contrast agent well filled area of left ventricular were delineated with a 13 mm diameter sphere (Cardiac Region of Interest, cardiac ROI) in a single phase. 3Dslicer software was used to extract 92 features of all the sketches, analyze the distribution of CT values on the cardiac ROI and LVM, and preliminarily screen the stable features based on the cardiac ROI (one-way ANOVA). The stable features were used to further screen LVM (one-way ANOVA) to get the difference features. Wilcoxon rank sum test was used to analyze the change of characteristics with heartbeat in the heartbeat cycle.Results:In the heartbeat cycle the mean CT values of cardiac cavity ROI in cardiac cavity changed less than that in LVM, with the change rates of 9.23% and 17.88%, respectively. There were 36 stable features with no significant difference in cardiac cavity ROI ( P>0.05). 20 of them were statistically significant ( F=1.641-6.206, P<0.05), and the average change rate was 98.63%, such as median (-103.96%) and mean (123.67%) of the first order matrix, gray level non uniformity (99.81%) of GLDM matrix and other changes reached more than 99%. The differences between the maximum and minimum values in different cardiac cycles were statistically significant ( Z=-3.921--3.173, P<0.05). Conclusions:With the combination of radiomics and enhanced ECG 4DCT image, the microscopic changes of CT image features in the cardiac cycle can be amplifed. A new method for the assessment of left ventricular function changes was provided. The features such as median, mean may have more application potential.
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Objective:To evaluate the cumulative dose of the target volume and organs at risk (OARs) in intensity-modulated radiation therapy (IMRT) for large volume non-small cell lung cancer (NSCLC) based on rigid and deformation registration methods. The dosimetric changes between the initial and second treatment plans were compared.Methods:Thirty patients treated with IMRT for large volume NSCLC with twice 4DCT scans acquired before radiotherapy and after 20 fractions of radiotherapy were recruited. The initial treatment plan (Plan 1) based on the average density projection CT (CT 1-avg) of the first 4DCT images and the second treatment plan (Plan 2) based on the average density projection CT (CT 2-avg) of the second 4DCT images were calculated. Then, the dose distributions of Plan 1 and Plan 2 were accumulated based on rigid and deformation registration methods to obtain Planrig and Plandef, respectively. Finally, the volume changes of gross tumor volume (GTV) and OARs between two CT scans were compared. The dose-volume parameters between Plan 1 and other plans (including Plan 2, Planrig and Plandef) were also statistically compared. Results:Compared with the initial CT scan, the mean volume of GTV and heart on the second CT was decreased by 44.2% and 5.5%, respectively, while the mean volume of ipsilateral lung, contralateral lung and total lung was increased by 5.2%, 6.2% and 5.8%, respectively (all P<0.05). Compared with Plan 1, the D 95%, D 98% and V 100% of target volume IGTV (GTV fusion of 10 4DCT phases) and PTV in Plan 2 did not significantly change (all P>0.05), and those in Planrig and Plandef were decreased (all P<0.05). The dose-volume parameters of spinal-cord, heart, ipsilateral lung and total lung in Plan 2, Planrig and Plandef were significantly lower than those in Plan 1(all P<0.05). Among them, the V 30Gy and D mean of heart were decreased by 27.3%, 16.5%, 15.3% and 15.2%, 6.6%, 5.6%, respectively. The V 20Gy and D mean of total lung were decreased by 15.6%, 4.5%, 3.7% and 15.7%, 6.2%, 5.1%, respectively. Some dose-volume parameters (including D 95% and D 98% of target volume, V 40Gy of heart, V 20Gy and D mean of the ipsilateral lung and the total lung) of Plandef were higher than those in Planrig (all P<0.05). The Dice similarity coefficients (DSCs) of OARs after deformation registration were significantly higher than those after rigid registration ( P<0.05). Conclusions:The dose-volume parameters of OARs significantly differ between Plan 1 and Plan 2. Hence, all these parameters have a large degree of deviation in predicting radiation-induced injury of OARs. Nevertheless, the dose-volume parameters obtained by deformation registration can enhance the prediction accuracy.
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Objective:To assess the feasibility of delayed-enhancement MRI in contouring the lumpectomy cavity (LC) for patients with invisible seroma or a low cavity visualization score (CVS≤2) in the excision cavity after breast-conserving surgery (BCS).Methods:Twenty-six patients with stage T 1-2N 0M 0 who underwent prone radiotherapy after BCS were recruited. The LC delineated on CT simulation images was denoted as LC CT. The LCs delineated on T 2WI, as well as on different delayed phases (2-, 5-and 10-minute) of delayed-enhancement T 1WI were defined as LC T2, LC 2T1, LC 5T1 and LC 10T1, respectively. Subsequently, the volumes and locations of the LCs were compared between CT simulation images and different sequences of MR simulation images using deformable image registration. Results:The volumes of LC T2, LC 2T1, LC 5T1 and LC 10T1 were all larger than that of LC CT. A statistical significance was found between the volume of LC CT and those of LC 2T1 or LC 5T1, respectively (both P<0.05). The conformal index (CI), degree of inclusion (DI), dice similarity coefficient (DSC) and the distance between the center of mass of the targets (COM) of LC CT-LC 10T1 were better than those of LC CT-LC T2, LC CT-LC 2T1 and LC CT-LC 5T1, however, there was no statistical difference among them (all P>0.05). Conclusions:It is feasible to delineate the LC based on prone delayed-enhancement MR simulation images in patients with low CVS after BCS. Meanwhile, the LCs derived from prone delayed-enhancement T 1WI of 10-minute are the most similar with those derived from prone CT simulation scans using titanium clips, regardless of the volumes and locations of LCs.
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Objective@#To study the effects of different CT values assignment methods on the dose calculation of radiotherapy plan for brain metastases, which will provide a reference for radiotherapy treatment planning based on MR images.@*Methods@#A total of 35 patients treated with radiotherapy for brain metastases were selected, with pre-treatment CT and MR simulated positioning performed at the same day. Based on the simulation CT images, three dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT) plans were calculated as the original plan (Plan1). The CT and MR images were rigidly registered and then the main tissues and organs were delineated on CT and MR images. The average CT values of each tissue and organ were calculated. Three groups of pseudo CT were generated by three CT values assignment methods based on the CT images: whole tissue was assigned 140 HU; cavity, bone and other tissues were assigned -700 HU, 700 HU and 20 HU, respectively; different tissues and organs were assigned corresponding CT values. The dose distribution of Plan1 was recalculated on three groups of pseudo-CT to obtain Plan2, Plan3 and Plan4, respectively. Finally, the dosimetric difference between Plan1 and other plans (including Plan2, Plan3 and Plan4) were compared.@*Results@#The average CT values of bone and cavity were (735.3±68.0) HU and (-723.9±27.0) HU, respectively. The average CT values of soft tissues was mostly distributed from -70 to 70 HU. The dosimetric differences between Plan2, Plan3, Plan4, and Plan1 decreased in turn. The differences of maximum dose of lens were the biggest, which can reach more than 5.0%, 1.5%-2.0% and 1.0%-1.5%, respectively, and the differences of other dose parameters were basically less than 2.0%, 1.2% and 0.8%, respectively. In the pixelwise dosimetric comparison, the areas with more than 1% difference in the local target cases were mainly distributed in the skin near the field. On the other hand, those in the whole brain target cases were mainly distributed at the bone, cavity, bone and soft tissues junction, and the skin near the field. In addition, the dose calculation error of CT value assignment methods in 3D-CRT plan was slightly larger than that in IMRT plan, and that in whole brain target cases were significantly larger than that in local target cases.@*Conclusions@#Different CT value assignment methods have a significant effect on the dose calculation of radiotherapy for brain metastases. When appropriate CT values are given to bone, air cavity and soft tissue, respectively, the deviation of dose calculation can be basically controlled within 1.2%. And by assigning mass CT values to various tissues and organs, the deviation can be further controlled within 0.8%, which can meet the clinical requirements.
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Objective@#To establish radiomics models based on different CT scaning phases to distinguish mediastinal metastatic lymph nodes in NSCLC and to explore the diagnostic efficacy of these models.@*Methods@#The CT images of 86 preoperative patients with NSCLC who were performed both plain and enhanced CT scans were analyzed retrospectively. The 231 mediastinal lymph nodes were enrolled in this study which were divided into two independent cohorts: 163 lymph nodes enrolled from January 2015 to June 2017 constituted the training cohort, and 68 lymph nodes enrolled from July 2017 to June 2018 constituted the validation cohort. The regions of interest (ROIs) were delineated on plain scan phase, arterial phase and venous phase CT images respectively, and 841 features were extracted from each ROI. LASSO-logistic regression analysis was used to select features and develop models. The area under the ROC curve (AUC value), sensitivity, specificity, accuracy, positive predictive value and negative predictive value of different models for distinguishing metastatic lymph nodes were compared.@*Results@#A total of 6 models were established, and the AUC values were all greater than 0.800. The plain CT model yielded the highest AUC, specificity, accuracy and positive predictive value with 0.926, 0.860, 0.871, 0.906 in the training cohort and 0.925, 0.769, 0.882, 0.870 in the validation cohort. When plain and venous phase CT images were combined with arterial phase CT images, the sensitivity and negative predictive value of the models increased from 0.879, 0.821 and 0.919, 0.789 to 0.949, 0.878 and 0.979, 0.900 respectively.@*Conclusions@#The CT radiomics model could be used to assist the clinical diagnosis of lymph nodes. The AUC value of the model based on plain scanning was the highest, while the sensitivity and negative predictive value of the model could be improved by combining the arterial phase CT images.
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Objective To investigate the changes of accumulated dose in target area and organs at risk (OARs) for radiotherapy of left breast cancer by deformable and rigid image registration.Methods A total of 16 left breast cancer patients treated with 6 MV X-ray IMRT were analyzed retrospectively.All targets included the lymph node drainage area and the chest wall.All patients underwent simulation of the primary positioning and repositioning to obtain CT images.Primary and secondary treatment plans were developed using primary positioning CT (CT1) and repositioning CT (CT2),denoted as Plan1 and Plan2 respectively.The dose distribution of Plan2 was mapped to CT1 with rigid and deformable registration from CT2 to CT1 and then added to the dose distribution of Planl to obtain Plan-rigid and Plan-deform,respectively.The dosimetric differences between targets and the OARs of the four plans were compared.Results The CTV volume on CT2 was reduced by 6.64％ from that on CT1.The homogeneity index (HI)increased by 23.05％ after deformation-based accumulation.The Dice similarity coefficients (DSCs) of the heart,left lung and right lung were lower than those before deformable registration (0.94±0.01 vs.0.89± 0.05,0.96±0.01 vs.0.91±0.03,and 0.96±0.01 vs.0.92±0.03,respectively),and the differences were statistically significant (Z =-3.208,-3.533,-3.535,P ＜ 0.05).There were no significant differences in dose-volume indices of heart and left lung between Plan1 with other plans (P＞0.05),while the dose-volume indices in Plan-rigid were higher than that in Plan-deform.Conclusions Rigid registration is recommended in patients undergoing radical resection of left breast cancer with little change in the volume and dose-volume index of the target area and organs at risk.The dose-volume index of the initial intensity modulation plan can basically reflect the dose-volume statistics of both lungs and heart.
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Objective@#To explore the ability of computed-tomography (CT) radiomic features to predict the Epidermal growth factor receptor (EGFR) mutation status and the therapeutic response of advanced lung adenocarcinoma to EGFR- Tyrosine kinase inhibitors (TKIs) treatment.@*Methods@#A retrospective analysis was performed on 253 patients diagnosed as advanced lung adenocarcinoma, who underwent EGFR mutation detection, and those with EGFR sensitive mutation were treated with TKIs. Using the Lasso regression model and the 10 fold cross-validation method, the radiomic features of predicted EGFR mutation status and the screening of TKIs for sensitive populations were obtained. 715 radiomic features were extracted from unenhanced, arterial phase and venous phase, respectively.@*Results@#The area under curve (AUC) values of the multi-phases including unenhanced, arterial phase and venous phase of the EGFR mutation status validation group were 0.763, 0.807 and 0.808, respectively. The number of radiomic features extracted from the multi-phases were 5, 18 and 23, respectively, which could distinguish the EGFR mutation status. The AUC values of the multi-phases of the EGFR-TKIs sensitive validation group were 0.730, 0.833 and 0.895, respectively. The number of radiomic features extracted from the multi-phases were 3, 7 and 22, respectively, which can be used to screen the superior population for TKIs treatment. The efficiency of radiomic features extracted from venous phase in predicting EGFR mutant status and EGFR-TKIs sensitivity was significantly superior than those of unenhanced and arterial phase.@*Conclusions@#The radiomic features of CT scanning can be used as the radiomics biomarker to predict the EGFR mutation status of lung adenocarcinoma and to further screen the dominant population in TKIs therapy, which provides the basis for targeted therapy.
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Objective@#To investigate the changes of accumulated dose in target area and organs at risk (OARs) for radiotherapy of left breast cancer by deformable and rigid image registration.@*Methods@#A total of 16 left breast cancer patients treated with 6 MV X-ray IMRT were analyzed retrospectively. All targets included the lymph node drainage area and the chest wall. All patients underwent simulation of the primary positioning and repositioning to obtain CT images. Primary and secondary treatment plans were developed using primary positioning CT (CT1) and repositioning CT (CT2), denoted as Plan1 and Plan2 respectively. The dose distribution of Plan2 was mapped to CT1 with rigid and deformable registration from CT2 to CT1 and then added to the dose distribution of Plan1 to obtain Plan-rigid and Plan-deform, respectively. The dosimetric differences between targets and the OARs of the four plans were compared.@*Results@#The CTV volume on CT2 was reduced by 6.64% from that on CT1. The homogeneity index (HI) increased by 23.05% after deformation-based accumulation. The Dice similarity coefficients (DSCs) of the heart, left lung and right lung were lower than those before deformable registration (0.94±0.01 vs. 0.89±0.05, 0.96±0.01 vs. 0.91±0.03, and 0.96±0.01 vs. 0.92±0.03, respectively), and the differences were statistically significant (Z=-3.208, -3.533, -3.535, P<0.05). There were no significant differences in dose-volume indices of heart and left lung between Plan1 with other plans(P>0.05), while the dose-volume indices in Plan-rigid were higher than that in Plan-deform.@*Conclusions@#Rigid registration is recommended in patients undergoing radical resection of left breast cancer with little change in the volume and dose-volume index of the target area and organs at risk. The dose-volume index of the initial intensity modulation plan can basically reflect the dose-volume statistics of both lungs and heart.
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Objective@#To analyze the magnetic resonance imaging (MRI) radiomic performance of hypoxic area in nasopharyngeal carcinoma patients, aiming to provide a reference for identification and analysis of hypoxic area.@*Methods@#The MRI-T1, MRI-T2, MRI-T1+ and PET/CT images of 32 patients initially diagnosed with nasopharyngeal carcinoma were retrospectively analyzed. The gross tumor volume (GTV) of nasopharynx was countoured and the hypoxic areas (GTV-H) were identified by 18F-FMISO-PET images. The non-hypoxic areas (GTV-NH) were defined as the rest of areas removed GTV-H from GTV. The radiomic features of GTV-H and GTV-NH were extracted and compared.@*Results@#The average volume of GTV-H and GTV-NH was (10.92±11.02) cm3 and (7.21±5.70) cm3, respectively. The maximum rate of change was 46% for intensity direct-global min (ID-GM) on MRI-T1(P<0.05, AUC>0.7 and Youden index>0.5). The average rate of change was 136% for long run emphasis (LRE), long run high gray level emphasis (LRHGLE) and long run low gray level emphasis (LRLGLE) on MRI-T2(P<0.05, AUC>0.7 and Youden index>0.5). The high change rates was greater than 90% on MRI-T1+ (P<0.05, AUC>0.7 and Youden index>0.5) for ID-GM, LRE, LRHGLE and LRLGLE.@*Conclusions@#The hypoxic area of tumor target can be reflected by MRI radiomics on T1/T2/T1+ . Quantifying and tracking the variations of these features can bring benefit to recognize the hypoxic area of nasopharyngeal carcinoma tumor target.
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Objective To investigate the impact of multi-b-value on texture features of DWI in liver cirrhosis.Methods DWI manifestations of liver cirrhosis in 37 patients were analyzed retrospectively,and DWI of 27 healthy volunteers (control group) were enrolled as controls.The b values were set as 0,20,50,100,200,400,800,1 000,1 200 and 1500 s/mm2,respectively.Three ROIs at different levels of every set image were selected,and 37 texture features within these ROIs were extracted.Unstable texture features affected by different b-values were screened with the percent coefficient of variation (％COV),and the fitting degree between the unstable texture features and b values were analyzed with exponential fitting.Results Among 37 texture features,20 (20/37,54.05 ％) were unstable.With the increase of b values,exponential upward trend was found in 10 texture features,exponential downward trend was found in 4 texture features,and the relative trends could not be defined in other 6 unstable texture features.Conclusion The b values of DWI impact the texture features in liver cirrhosis.Correlations exist among some texture features and b values.
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The accurate diagnosis and precise prediction of tumor radiation sensitivity and normal tissue radiation-induced injury are the preconditions of precise radiotherapy for lung cancer.Radiomics is defined as a set of milestone,assistive tools in the develop-ment of precise treatment for lung cancer,which can extract many quantitative features from medical images by applying automatic or semi-automatic methods and determine the deep relationship between clinical diagnosis and treatment data.Thus,the occurrence, development,and clinical outcome of lung cancer may be revealed.Radiomics holds immense potential in the classification of benign and malignant lung nodules,prediction of lung cancer genetic phenotypes,and treatment response to radiation therapy,because it can obtain information regarding the global heterogeneity of tumors via a noninvasive approach.In the present review,we summarize the latest process of CT-based radiomics in precise radiotherapy for lung cancer.
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Objective To study the impact of heartbeat on the left ventricular myocardial (mLV) and the left anterior descending (LAD) coronary arterial dosimetry following intensity modulated radiotherapy (IMRT) for left-sided breast carcinoma.Methods A total of 15 female patients who received electrocardiography gated 4D-CT scan in inspiratory breathing-holding were enrolled.According to cardiac cycle,20 time-phase images were reconstructed from 0 to 95％ at 5％ interval.Then,the mLV and the LAD were delineated respectively and the IMRT plans of the left breast carcinoma were generated based on 0％ phase CT images.The volume and dice similarity coefficient (DSC) of the mLV were calculated,and the variation range of the mLV and the LAD dose-volume indexes were compared among different phases.Results The average rate of DSC variation of mLV was eightfold of volume,which reached to 472.07％,and the average change rate of mLV (Dmean) was up to 41.95％.The difference of the mLV's volume and DSC was statistically significant between the maximum and minimum(t =-6.585,-28.870,P＜0.05),as well as the D V10,V20,V30 and V40(t=-5.260,-4.084,-3.592,-3.273,-2.566,P ＜0.05).The average change rate of the LAD's D was up to 130.14％.The difference of D V10,V20,V30 and V40 of LAD was statistically significant between the maximum and minimum(t =-9.758,-8.810,-8.682,-7.853,-6.205,P ＜ 0.05).Conclusions The dosimetry impact of heartbeat on mLV and LAD should not be ignored.
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Radiomics has played an irreplaceable role along with the development of precision medicine. In the field of radiomics researches,the stability of imaging features is of vital significance,which is directly linked to the modeling analysis. In this review,we summarized the recent research progress on the reproducibility problems in four crucial steps of the standard workflow of radiomics including imaging acquisition and reconstruction, region of interest(ROI)segmentation, imaging feature extraction and modeling establishment. In addition,the commonly used software related to radiomics was briefly introduced.