Objective To evaluate the safety and clinical efficacy of stereotactic body radiation therapy (SBRT) for lung cancer.Methods A retrospective analysis was performed on 200 patients with primary non-small cell lung cancer (NSCLC)(118 patients) or solitary pulmonary metastasis (82 patients) who underwent SBRT in Zhejiang Cancer Hospital from January 2012 to September 2015.The 80% isodose line covered 95% of the planning target volume,and the 100% isodose line covered 100% of the internal gross tumor volume.The fractional dose was 4.0-18.0 Gy daily or every other day,and the biologically equivalent dose ranged from 40.0 to 151.2 Gy (median 100 Gy).Results All patients completed treatment.The follow-up rate was 96.0%.The complete response and partial response rates were 14.8%(17/115) and 65.2%(75/115) for the primary tumor group,versus 25%(19/77) and 38%(29/77) for the metastasis group.The incidence rates of grade Ⅱ and Ⅲ acute radiation pneumonitis were 4.7% and 3.1%,respectively.The median follow-up was 14.9 months.The 1-and 2-year local control rates were 95.7% and 84.3% for the primary tumor group,versus 92% and 73% for the metastasis group.The 1-and 2-year overall survival rates were 94.5% and 92.0% for the primary tumor group,versus 85% and 62% for the metastasis group.Conclusions SBRT is a safe and effective treatment for early primary NSCLC and solitary pulmonary metastasis,resulting in high 1-and 2-year local control and overall survival rates and low rate of complications.

Objective: To study a lung dose prediction method for the early stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiotherapy based on machine learning algorithm, and to evaluate the feasibility of application in planning quality assurance. Methods: A machine learning algorithm was utilized to achieve DVH prediction. First, an expert plan dataset with 125 cases was built, and the geometric features of ROI, beam angle and dose-volume histogram(DVH) parameters in the dataset were extracted. Following a correlation model was established between the features and DVHs. Second, the geometric and beam features from 10 cases outside the training pool were extracted, and the model was adopted to predict the achievable DVHs values of the lung. The predicted DVHs values were compared with the actual planned results. Results: The mean squared errors of external validation for the 10 cases in mean lung dose (MLD)MLD and V₂₀ of the lung were 91.95 cGy and 3.12%, respectively. Two cases whose lung doses were higher than the predicted values were re-planned, and the results showed that the the lung doses were reduced. Conclusion It is feasible to utilize the anatomy and beam angle features to predict the lung DVH parameters for plan evaluation and quality assurance in early stage NSCLC patients treated with stereotactic body radiotherapy

Objective To identify the exact locations of the brain being irradiated in advanced nasopharyngeal carcinoma(NPC)patients during radiotherapy,and to analyze the differences in brain dose distribution between advanced NPC patients treated with intensity-modulated radiotherapy(IMRT)and volumetric modulated arc therapy(VMAT).Methods Based on the CT brain template provided by the Montreal Neurological Institute,the brain dose distribution was analyzed with voxel-based method.Results For advanced NPC patients,VMAT plans did not demonstrate superiority in normal brain tissue sparing,while IMRT performed better,with advantages observed in regions such as the brainstem,the posterior lobe of the cerebellum,the anterior lobe of the cerebellum,temporal lobes,occipital lobes,limbic lobes,and certain areas of the subcortical regions.Conclusion IMRT is advantageous over VMAT in protecting the normal brain tissues in advanced NPC patients.

Objective To evaluate the clinical efficacy between stereotactic body radiotherapy (SBRT) and surgical treatment for stage Ⅰ-Ⅱ non-small cell lung cancer (NSCLC).Methods Clinical data of 120 patients with early-stage NSCLC who underwent SBRT or surgical treatment in Zhejiang Cancer Hospital from 2012 to 2015 were retrospectively analyzed.Propensity score matching was carried out between two groups.Sixty eligible patients were enrolled in each group.In the SBRT group,the 80％ isodose line covered 95％ of the planning target volume,and the 100％ isodose line covered 100％ of the internal gross tumor volume.The fractional dose was 5-15 Gy and the median biologically equivalent dose was 100 Gy (range:57.6-150.0 Gy).In the operation group,32 patients underwent video-assisted thoracoscopic lobectomy and 9 patients underwent wedge resection or segmentectomy.Results All patients successfully completed corresponding treatment and were followed up.The median follow-up was 32.3 months (range:8.6-68.4 months).In the operation group,3 patients died from infection within postoperative 90 d,whereas no case died in the SBRT group (P=0.079).In the SBRT group,3 patients died of other factors besides tumor (cerebral infarction,heart disease,etc.) during follow-up.Local-regional recurrence occurred in 12 patients including 5 cases in the operation group and 7 in the SBRT group (P=0.543).In the operation group,11 patients experienced distant metastases with a median disease-free survival (DFS) of 33.5 months.In the SBRT group,6 patients had distant metastases and the median DFS was 38.4 months (P=0.835,P=0.178).In the SBRT group,the 1-and 3-year overall survival rates were 93％ and 83％,and 95％ and 83％ in the operation group (P=0.993).Conclusions The 1-and 3-year overall survival rates and local control rate do not significantly differ between SBRT and operation for patients with early-stage NSCLC.

Objective To perform 3D dose reconstruction based on electronic portal imaging device ( EPID) of linear accelerator for the static intensity-modulated using Edose, a dose verification system, Aiming to assist the radiotherapy professionals to better understand the radiotherapy organs at risk and target dose changes. Methods CBCT image was acquired for patients with head and neck cancer and thoracic cancer once a week for a total of six times. Subsequently,CBCT images and planning CT images were subject to rigid registration and exported to the Edose software. According to the setup error, EPID-based three-dimensional dose reconstruction was performed by using Edose software. The gamma passing rate and dose of different organs at risk ( OARs ) were analyzed and statistically compared. Results For patients with nasopharyngeal carcinoma,the intra-fractional Dmax of the spinal cord was more significantly fluctuated and higher compared with the planning dose, whereas the intra-fractional Dmax of the brainstem did not significantly fluctuate. The V30 of the parotid gland significantly changed with a maximum increase of 28. 69％ per fraction. For patients with thoracic tumors,the Dmax of the spinal cord was slightly changed,and the actual doses in the lung and heart were higher than the planning doses. The average deviation of the pulmonary V5 was up to 16. 99％ between the actual and planning doses with statistical significance ( P<0. 05).According to the analysis of gamma passing rate,significant dose changes occurring in the OARs were detected in the 16th fraction for the head and neck cancer and the 24th fraction for the thoracic neoplasms. Conclusions The dose changes in the OARs can be obtained by reconstructing the EPID-based 3D dose distribution using the Edose software for each fraction, which can better protect the OAR, enhance the coverage of target dose and provide certain reference for dose-guided and self-adaptive radiotherapy.

Objective:To evaluate the clinical efficacy and safety of stereotactic body radiation therapy (SBRT) for stage Ⅰ-Ⅱ non-small cell lung cancer.Methods:Retrospective analysis of patients with early stage lung cancer who received SBRT in Zhejiang Cancer Hospital from 2012 to 2018 was conducted. The Kaplan-Meier method was used for survival analysis. The main endpoints of the study were locoregional control (LRC) and cancer specific survival (CSS).Results:A total of 142 eligible cases were included, with a median BED10100Gy (100-132Gy). The median age was 75.6 years (47.2-89.0 years), among which 75 patients were aged (greater than or equal to 75 years old). The median follow-up time was 31.0 months, for patients< 75 years old and patients ≥ 75 years old. The 5-year LRC were 84.5% and 95.8% respectively, 5-year CSS were 72.4% and 78.6% respectively, for patients< 75 years old and elderly patients. The systemic response was mild during treatment, no grade 4-5 adverse events occurred in all patients. The main acute side effect was radiation pneumonitis (RP) below grade 3. Grade 2 RP appeared in 14 patients (9.9%) after SBRT where grade 3 RP occurred in 2(1.4%). There was no treatment-related mortality in the SBRT group.Conclusions:SBRT is a safe and effective treatment for early primary lung cancer with satisfactory rates of LRC and CSS in 5 years and mild complication, which is similar to previous reports.

Objective:To explore a three-dimensional dose distribution prediction method for the left breast cancer radiotherapy planning based on full convolution network (FCN), and to evaluate the accuracy of the prediction model.Methods:FCN was utilized to achieve three-dimensional dose distribution prediction. First, a volumetric modulated arc therapy (VMAT) plan dataset with 60 cases of left breast cancer was built. Ten cases were randomly chosen from the dataset as the test set, and the remaining 50 cases were used as the training set. Then, a U-Net model was built with the organ structure matrix as inputs and dose distribution matrix as outputs. Finally, the model was adopted to predict the dose distribution of the cases in the test set, and the predicted 3D doses were compared with actual planned results.Results:The mean absolute differences of PTV, ipsilateral lung, heart, whole lung and spinal cord for 10 cases were (119.95±9.04) cGy, (214.02±9.04) cGy, (116.23±30.96) cGy, (127.67±69.19) cGy, and (37.28±18.66) cGy, respectively. The Dice similarity coefficient (DSC) of the prediction dose and the planned dose in the 80% and 100% prescription dose range were 0.92±0.01 and 0.92±0.01. The γ rate of 3 mm/3% in the area of 80% and 10% prescription dose range were 0.85±0.03 and 0.84±0.02. Conclusion:FCN can be used to predict the three-dimensional dose distribution of left breast cancer patients undergoing VMAT.

Objective:To evaluate the application of a multi-task learning-based light-weight convolution neural network (MTLW-CNN) for the automatic segmentation of organs at risk (OARs) in thorax.Methods:MTLW-CNN consisted of several layers for sharing features and 3 branches for segmenting 3 OARs. 497 cases with thoracic tumors were collected. Among them, the computed tomography (CT) images encompassing lung, heart and spinal cord were included in this study. The corresponding contours delineated by experienced radiation oncologists were ground truth. All cases were randomly categorized into the training and validation set ( n=300) and test set ( n=197). By applying MTLW-CNN on the test set, the Dice similarity coefficients (DSCs) of 3 OARs, training and testing time and space complexity (S) were calculated and compared with those of Unet and DeepLabv3+ . To evaluate the effect of multi-task learning on the generalization performance of the model, 3 single-task light-weight CNNs (STLW-CNNs) were built. Their structures were totally the same as the corresponding branches in MTLW-CNN. After using the same data and algorithm to train STLW-CNN, the DSCs were statistically compared with MTLW-CNN on the testing set. Results:For MTLW-CNN, the averages (μ) of lung, heart and spinal cord DSCs were 0.954, 0.921 and 0.904, respectively. The differences of μ between MTLW-CNN and other two models (Unet and DeepLabv3+ ) were less than 0.020. The training and testing time of MTLW-CNN were 1/3 to 1/30 of that of Unet and DeepLabv3+ . S of MTLW-CNN was 1/42 of that of Unet and 1/1 220 of that of DeepLabv3+ . The differences of μ and standard deviation (σ) of lung and heart between MTLW-CNN and STLW-CNN were approximately 0.005 and 0.002. The difference of μ of spinal cord was 0.001, but σof STLW-CNN was 0.014 higher than that of MTLW-CNN.Conclusions:MTLW-CNN spends less time and space on high-precision automatic segmentation of thoracic OARs. It can improve the application efficiency and generalization performance of the models.

Objective: To investigate the clinical efficacy and adverse effects of stereotactic body radiotherapy (SBRT) in the treatment of T₂N₀M₀ non-small cell lung cancer (NSCLC) patients. Methods: By retrospectively analyzing the clinical data of 30 inoperable patients with stage T₂N₀M₀ NSCLC treated by SBRT, the overall survival, progression-free survival, cancer-specific survival and adverse effects were determined. Results: The median follow-up was 18.4 months. The 1-, 2-, and 3-year overall survival rates were 92.2%, 92.2% and 80.6%, respectively. The corresponding cause-specific survivals were 95.7%, 95.7% and 83.7%. The progression-free survivals were 70.2%, 54.1% and 40.6%. The local control rates were 100%, 94.4%, and 94.4%. The regional controls were 84.2%, 72.1%, and 54.1%; and distant controls were 84.6%, 72.4% and 64.3%, respectively. Twenty patients (66.7%) developed symptoms of grade 1 radiation-related toxicities: dyspnea, chest pain, fatigue, cough, esophagitis, or pneumonia. Among these, 5 patients suffered grade ≥2 radiation pneumonitis, and one patient experienced grade 4 radiation pneumonitis. Conclusions SBRT was efficient and safe for patients with inoperable T₂N₀M₀ NSCLC, imposing tolerable toxicities.

Objective: To investigate the feasibility and dosimetric characteristics of using dual-arc volumetric modulated arc therapy and multiple partial-arc VMAT for T3 lung cancer. Methods: From June 2016 to May 2018, thirteen lung cancer patients with large planning target volume were replanned with dual full arcs VMAT(F-VMAT) and six partial-arc s VMAT(P-VMAT)on RayStation v4.5 RayArc function.PTV volume median was 550.9cm³(ranged 402.2-834.8cm³) and to a prescribed dose of 60 Gy in 30 fractions.Equivalent target coverage was required for all plans, and clinical goals were evaluated using various dose-volume metrics.These included PTV dose conformity, mean lung/heart dose, lung V₅, V₁₀, V₂₀, V₃₀, heart V₃₀ and V₄₀, and Dmax of spinal canal.The total monitor units (MUs) were also examined. Results: All VMAT plans satisfied the treatment criteria.F-VMAT achieved better homogeneity index(HI) and MUs than P-VMRT(t=-3.904, P=0.002), and the conformal number(CN) of tumor volumes was likely clinically indistinguishable.However, F-VMAT significantly reduced lung V₅, V₁₀ and mean lung dose[V5: (51.31±5.36)% vs.(43.44±5.28)%, t=6.908, P=0.00; V10: (38.34±3.26)% vs.(34.05±3.74)%, t=4.632, P=0.001; Dmean: (1 449±117.19)cGy vs.(1 375.38±148.98)cGy, t=4.93, P=0.00], and heart dosimetric parameters were also observed in favor of P-VMRT[V₃₀: (20.6±10.4)% vs.(16.4±8.9)%, t=3.822, P=0.02; V₄₀: (14.6±7.5)% vs.(11.88±7.1)%, t=3.096, P=0.009; Dmean: (1 442.9±651.2)cGy vs.(1 263.5±605.6)cGy, t=3.986, P=0.02], and there were no statistically significant differences in lung V₂₀, V₃₀ and spinal cord Dmax between the two groups(all P>0.05). Conclusion VMAT is an effective treatment for stage T3 lung cancer patients.The primary advantage of P-VMAT was the reduction in low dose area and decreased risk of symptomatic radioactive lung injury.It may be a priority for pulmonary malignancy patients with the large planning target volume.