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Objective:To evaluate the practicability of dose volume histogram (DVH) prediction model for organ at risk (OAR) of radiotherapy plan by minimizing the cost function based on equivalent uniform dose (EUD).Methods:A total of 66 nasopharyngeal carcinoma (NPC) patients received volume rotational intensity modulated arc therapy (VMAT) at Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences from 2020 to 2021 were retrospectively selected for this study. Among them, 50 patients were used to train the recurrent neutral network (RNN) model and the remaining 16 cases were used to test the model. DVH prediction model was constructed based on RNN. A three-dimensional equal-weighted 9-field conformal plan was designed for each patient. For each OAR, the DVHs of individual fields were acquired as the model input, and the DVH of VMAT plan was regarded as the expected output. The prediction error obtained by minimizing EUD-based cost function was employed to train the model. The prediction accuracy was characterized by the mean and standard deviation between predicted and true values. The plan was re-optimized for the test cases based on the DVH prediction results, and the consistency and variability of the EUD and DVH parameters of interest (e.g., maximum dose for serial organs such as the spinal cord) were compared between the re-optimized plan and the original plan of OAR by the Wilcoxon paired test and box line plots.Results:The neural network obtained by training the cost function based on EUD was able to obtain better DVH prediction results. The new plan guided by the predicted DVH was in good agreement with the original plan: in most cases, the D 98% in the planning target volume (PTV) was greater than 95% of the prescribed dose for both plans, and there was no significant difference in the maximum dose and EUD in the brainstem, spinal cord and lens (all P>0.05). Compared with the original plan, the average reduction of optic chiasm, optic nerves and eyes in the new plans reached more than 1.56 Gy for the maximum doses and more than 1.22 Gy for EUD, and the average increment of temporal lobes reached 0.60 Gy for the maximum dose and 0.30 Gy for EUD. Conclusion:The EUD-based loss function improves the accuracy of DVH prediction, ensuring appropriate dose targets for treatment plan optimization and better consistency in the plan quality.
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Objective:To identify dose-volume parameters to predict the incidence of acute intestinal toxicity in cervical cancer patients after postoperative adjuvant radiotherapy.Methods:Clinical data of 93 cervical cancer patients who underwent postoperative adjuvant intensity-modulated radiotherapy (IMRT) were retrospectively evaluated. The dose-volume parameters comprised the absolute volume of the bowel receiving 5-45 Gy (5 Gy interval) radiation dose and the total volume of the bowel. The acute radiation-induced intestinal toxicity was evaluated by Radiation Therapy Oncology Group (RTOG) criteria. The association between the irradiated bowel volume and acute intestinal toxicity was analyzed.Results:A total of 26 (28%) patients experienced grade ≥2 acute intestinal toxicity. A strong relationship between grade ≥2 acute intestinal toxicity and the irradiated small bowel volume was observed at the total volume of small bowel, small bowel V 5 Gy, V 10 Gy and V 15 Gy (all P<0.05). Small bowel V 10 Gy ( HR=1.028, 95% CI, 0.993-1.062, P=0.029) and small bowel ?V 15 Gy( HR=0.991, 95% CI, 0.969-1.013, P=0.034)were the independent risk factors for evident acute intestinal toxicity. Conclusion:Dose-volume parameters of the small bowel can be used as predictors for the occurrence of grade ≥2 acute intestinal toxicity in cervical cancer patients undergoing postoperative adjuvant radiotherapy.
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Objective:To analyze the local recurrence patterns after concurrent chemoradiotherapy (CCRT) for thoracic esophageal squamous cell carcinoma (ESCC) through image fusion, and to explore the risk factors of local recurrence and its relationships with dosimetric indices.Methods:A retrospective analysis was conducted for 209 thoracic ESCC patients who received radical CCRT in Fourth Hospital of Hebei Medical University during 2016-2019. For the patients diagnosed as the local recurrence of esophageal lesions, their CT images were fused with the original planning CT images using image registration software to identify the recurrence sites. Through 1∶1 propensity score matching (PSM) of the clinal data of patients with local recurrence (the recurrence group, nbefore = 81, nafter = 62) and those without local recurrence (the recurrence-free group, nbefore = 128, nafter=62), the dose and volume parameters of the treatment plans for the two groups were compared. Univariate and multivariate analyses were conducted using the Kaplan-Meier method and the Cox regression model to analyze the factors affecting the overall survival (OS), progression-free survival (PFS), and recurrence-free survival (RFS). Results:All patients had 1-, 3-, and 5-year OS rates of 80.9%, 42.6%, and 33.0%, respectively, 1-, 3-, and 5-year PFS rates of 67.9%, 34.0%, and 27.9%, respectively, and 1-, 3-, and 5-year RFS rates of 71.3%, 39.2%, and 30.5%, respectively. T stage, N stage, and radiation dose were independent prognostic factors for the OS, PFS, and RFS ( HR = 1.42-1.87, P < 0.05) of the patients, respectively. Among 68 patients with local recurrence, 62 cases (91.2%) suffered recurrence within the gross tumor volume (GTV). The dose and volume parameters of patients with local recurrence, such as GTV- D95%, clinical target volume (CTV)- D95%, GTV- D50%, CTV- D50%, and planning target volume (PTV)- D50%, GTV- V60, CTV- V60, and PTV- V60, were significantly lower than those of patients free from the local recurrence ( t=1.90-2.15, P < 0.05). Conclusions:Local recurrence of patients with thoracic ESCC after radical CCRT occurs mainly within the GTV. Increasing radiation doses may contribute to their survival benefits. The D50% for each target volume in the radiotherapy plan may be related to local recurrence, and it is necessary to conduct further research.
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Objective:To evaluate the volumetric modulated arc therapy (VMAT) dose verification of cervical cancer based on γ rule and dose volume histogram (DVH) and to perform correlation analysis between the evaluation results and the dose differences.Methods:Twenty cervical cancer VMAT plans were selected and performed on TrueBeam Linac. The delivered point and surface dose was measured by FC-65 G and ArcCheck and the results were compared to those calculated by Eclipse. The dose of patients was reconstructed by 3DVH. Then, differences between the reconstructed and plan value of D mean, D 95%, D 98% and D 2% of PTV, V 20Gy of left and right femoral head, V 40Gy of rectum, D 1cm 3 of cord, D 98%, D 2% and D 50% of the 50% prescription iso-dose volume (IDV), were evaluated and 3-dimensional (3D) γ was assessed for each organ. Lastly, Pearson’s correlation coefficient was used to analyze the relationship between point dose difference, 2D γ pass-rate (γ%), γ mean and 3D γ% of each organ and the dose difference. Results:Small differences were found between the point dose measured, reconstructed and the plan value. Differences between D mean of PTV, all dose parameters of IDV and plan values were all within 3% and V 40Gy of rectum showed the largest difference. As for the 3D γ%, the maximum pass rate was found for the left and right femoral head and the maximum variance for cord D 1cm 3. There was a moderate correlation between measured and reconstructed point dose deviation and dose difference of each organ, while no significant correlation was found for 2D γ%. Strong correlation was found between 3D γ% of target and D 50% of PTV/IDV and no correlation was found for other organs. Conclusion:The performance of both γ-and DVH-based evaluation can reveal dose error for dose verification, but both of them have some limitations and should be combined in clinical practice.
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Objective:To evaluate the pancreatic subclinical dysfunction after intensity-modulated radiation therapy (IMRT) for gastric cancer by analyzing biochemical indexes and pancreatic volume changes, and to reduce the dose of pancreas by dosimetric prediction and dose limitation.Methods:30 patients with gastric cancer who received 45 Gy postoperative adjuvant radiotherapy were retrospectively selected. The pancreas was delineated and its dose and anatomical relationship with planning target volume (PTV) were evaluated. Fasting blood glucose, serum lipase and amylase, and pancreatic volume changes before and after radiotherapy were analyzed. The correlation between the changes of biochemical indexes and volume and pancreatic dose was evaluated by Pearson analysis. The threshold of the dosimetric prediction was obtained by receiver operating characteristic (ROC) curve. Finally, the feasibility of dosimetric limitation in IMRT was assessed.Results:The pancreatic volume of 30 patients was 37.6 cm 3, and 89.0% of them were involved in PTV. D mean of the pancreas was 45.92 Gy, and 46.45 Gy, 46.46 Gy and 45.80 Gy for the pancreatic head, body and tail, respectively. The fasting blood glucose level did not significantly change. The serum lipase levels were significantly decreased by 66% and 77%(both P<0.001), and the serum amylase levels were significantly declined by 24% and 38%(both P<0.001) at 6 and 12 months after radiotherapy. Pancreatic volumes of 22 patients was decreased by 47% within 18 months after radiotherapy. ROC curve analysis showed that pancreatic V 45Gy had the optimal predictive value for the decrease by 1/3 of serum lipase and amylase levels at 6 months and serum amylase level at 12 months after radiotherapy, and the cut-off value was V 45Gy<85%. Pancreatic D mean yielded the optimal predictive value for the decrease by 2/3 of serum lipase level at 12 months after radiotherapy, and the cut-off value was D mean<45.01 Gy. After" whole pancreas" and" outside PTV pancreas" dose limit, V 45Gy of the pancreas was decreased by 11% and 7%, D mean of the pancreas was declined by 2% and 2%, and D mean of the pancreatic tail was decreased by 3%, respectively. Conclusions:Serum lipase and amylase levels significantly decline at 6 and 12 months after adjuvant radiotherapy for gastric cancer, and pancreatic volume is decreased significantly within 18 months after radiotherapy. Pancreatic V 45Gy<85% and D mean<45.01 Gy are the dose prediction values for the decrease of serum lipase and amylase levels. The dose can be reduced to certain extent by dosimetric restriction.
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BACKGROUND@#The incidence of symptomatic radiation pneumonitis (RP) and its relationship with dose-volume histogram (DVH) parameters in non-small cell lung cancer (NSCLC) patients receiving epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and concurrent once-daily thoracic radiotherapy (TRT) remain unclear. We aim to analyze the values of clinical factors and dose-volume histogram (DVH) parameters to predict the risk for symptomatic RP in these patients.@*METHODS@#Between 2011 and 2019, we retrospectively analyzed and identified 85 patients who had received EGFR-TKIs and once-daily TRT simultaneously (EGFR-TKIs group) and 129 patients who had received concurrent chemoradiotherapy (CCRT group). The symptomatic RP was recorded according to the Common Terminology Criteria for Adverse Event (CTCAE) criteria (grade 2 or above). Statistical analyses were performed using SPSS 26.0.@*RESULTS@#In total, the incidences of symptomatic (grade≥2) and severe RP (grade≥3) were 43.5% (37/85) and 16.5% (14/85) in EGFR-TKIs group vs 27.1% (35/129) and 10.1% (13/129) in CCRT group respectively. After 1:1 ratio between EGFR-TKIs group and CCRT group was matched by propensity score matching, chi-square test suggested that the incidence of symptomatic RP in the MATCHED EGFR-TKIs group was higher than that in the matched CCRT group (χ2=4.469, P=0.035). In EGFR-TKIs group, univariate and multivariate analyses indicated that the percentage of ipsilateral lung volume receiving ≥30 Gy (ilV30) [odds ratio (OR): 1.163, 95%CI: 1.036-1.306, P=0.011] and the percentage of total lung volume receiving ≥20 Gy (tlV20) (OR: 1.171, 95%CI: 1.031-1.330, P=0.015), with chronic obstructive pulmonary disease (COPD) or not (OR: 0.158, 95%CI: 0.041-0.600, P=0.007), were independent predictors of symptomatic RP. Compared to patients with lower ilV30/tlV20 values (ilV30 and tlV20<cut-off point values) and without COPD, patients with higher ilV30/tlV20 values (ilV30 and tlV20>cut-off point values) and COPD had a significantly higher risk for developing symptomatic RP, with a hazard ratio (HR) of 1.350 (95%CI: 1.190-1.531, P<0.001).@*CONCLUSIONS@#Patients receiving both EGFR-TKIs and once-daily TRT were more likely to develop symptomatic RP than patients receiving concurrent chemoradiotherapy. The ilV30, tlV20, and comorbidity of COPD may predict the risk of symptomatic RP among NSCLC patients receiving EGFR-TKIs and conventionally fractionated TRT concurrently.
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Humans , Carcinoma, Non-Small-Cell Lung/radiotherapy , ErbB Receptors/genetics , Lung Neoplasms/radiotherapy , Protein Kinase Inhibitors/adverse effects , Pulmonary Disease, Chronic Obstructive/complications , Radiation Pneumonitis/etiology , Radiotherapy Dosage , Retrospective StudiesABSTRACT
Objective To compare the dosimetric difference between the biological function based on equivalent uniform dose (EUD) and the physical function based on dose volume (DV) in the intensity modulated radiotherapy for stage Ⅲ non-small cell lung cancer. Methods Four different radiotherapy plans were designed for 15 stage Ⅲ non-small cell lung cancer patients: Group A, physical function optimization (DV + DV) was used for target area and organs at risk; GroupB, in the target region, biological function optimization conditions were added on the basis of physical function optimization, and physical function optimization of organs at risk (DV－EUD + DV) was added. Group C, biological function optimization (EUD + EUD) was used for target area and organs at risk. Group D, in the target area, physical function optimization conditions were added on the basis of biological function optimization, and biological function optimization of organs at risk (EUD－DV + DV) was added. The differences in dosimetric parameters of the four plans were compared. Results Target area: PTV: D2%, D98%, D50%, D105% and Dmax values of group C (P < 0.05) is the highest while group B and group D were relatively small (P > 0.05); The homogeneity index: the results of the group B and the group D were better than those of the other two groups (P < 0.05). conformity index: The results of the four groups were similar (P>0.05). Organ at risk: lung tissue mean dose (MLD), V5, V10, V20, V30 and heart V30, V40, Dmean dose parameters were similar (P > 0.05). Spinalcord: Group C and group D D1% were better than the other two groups (P < 0.05). There was no statistical difference in the number ofmonitor unit (MU) among the four groups (P > 0.05). Conclusion The optimization method combining physical and biological function optimization in the target area can improve the conformity of the target area on the premise of ensuring the treatment. The Spinalcord load would be significantly reduced when using biological function optimization or the combination of biological function and physical function optimization.
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Objective To analyze the correlation between ≥grade 2 radiation pneumonitis (RP) and dose volume parameters of elderly patients with esophageal cancer after three-dimensional conformal radiotherapy. Methods We collected the data of 250 elderly patients with esophageal cancer who received three-dimensional conformal radiotherapy from different medical centers. The clinical features of patients were analyzed by Chi-square test while dose volume parameters were analyzed by Logistic univariate and multivariate analyses. ROC curve was used to determine the best cut-off value. Results After three-dimensional conformal radiotherapy, 20% of patients developed ≥grade 2 RP. Univariate analysis showed that bilateral pulmonary V5, V10, V20, V30 and mean lung dose were associated with ≥grade 2 RP but multivariate analysis revealed that only V5 and V20 were independent relevant factors of RP. ROC curve indicated that the best cut-off value was V5 < 52.9% and V20 < 23.2%. Conclusion Bilateral pulmonary V5 and V20 are independently related to ≥grade 2 RP in elderly patients with esophageal cancer after 3-D conformal radiotherapy.
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Objective:To establish a local effect model (LEM)-based rectal dose volume histogram (DVH) prediction model in prostate cancer patients treated with carbon ion therapy based on Japanese experience, aiming to provide reference for clinically reducing the incidence of rectal adverse reactions.Methods:The planning CT data of 76 patients with prostate cancer were collected. The microdosimetric kinetic model (MKM) was used for initial planning, and the LEM was selected to recalculate the biological dose based on the same fields to MKM. Then, the geometric features and DVH of the rectum were extracted from the LEM plans. The planning data of 61 cases were used to establish the prediction model with linear regression and the other 15 cases were used for validation.Results:The ratio of the overlapped volume between the rectum and the region of interest (ROI) expended from planning target volume by 1 cm along the left and right directions of the rectum could be proved to be the characteristic parameters for linear regression. The mean goodness-of-fit R2 of predicted and LEM plan-based DVH of 15 cases was 0.964. The results of predicted rectal adverse reactions based on predicted DVH were consistent with those of LEM plan-based DVH. Conclusions:The linear regression method used in this study can establish an accurate prediction model of rectal DVH, which may provide certain reference for reducing the incidence of rectal adverse reactions. Nevertheless, the findings remain to be further verified by clinical trials with larger sample size.
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Objective:To establish an automatic planning method using volumetric-modulated arc therapy (VMAT) for primary liver cancer (PLC) radiotherapy based on predicting the feasibility dose-volume histogram (DVH) and evaluate its performance.Methods:Ten patients with PLC were randomly chosen in this retrospective study. Pinnacle Auto-Planning was used to design the VMAT automatic plan, and the feasibility DVH curve was obtained through the PlanIQ dose prediction, and the initial optimization objectives of the automatic plan were set according to the displayed feasible objectives interval. The plans were accessed according to dosimetric parameters of the planning target volume and organs at risk as well as the monitor units. All patients′ automatic plans were compared with clinically accepted manual plans by using the paired t-test. Results:There was no significant difference of the planning target volume D 2%, D 98%, D mean or homogeneity index between the automatic and manual plans ((58.55±2.81) Gy vs.(57.98±4.17) Gy, (47.15±1.58) Gy vs.(47.82±1.38) Gy, (53.14±0.95) Gy vs.(53.44±1.67) Gy and 1.15±0.05 vs. 1.14±0.07, all P>0.05). The planning target volume conformity index of the manual plan was slightly higher than that of the automatic plan (0.77±0.08 vs. 0.69±0.06, P<0.05). The mean doses of normal liver, V 30Gy, V 20Gy, V 10Gy, V 5Gy and V< 5Gy of the automatic plan were significantly better than those of the manual plan ((26.68±11.13)% vs.(28.00±10.95)%, (29.96±11.50)% vs.(31.89±11.51)%, (34.88±11.51)% vs.(38.66±11.67)%, (45.38±12.40)% vs.(50.74±13.56)%, and (628.52±191.80) cm 3vs.(563.15±188.39) cm 3, all P<0.05). The mean doses of the small intestine, the duodenum, and the heart, as well as lung V 10 of the automatic plan were significantly less than those of the manual plan ((1.83±2.17) Gy vs.(2.37±2.81) Gy, (9.15±9.36) Gy vs.(11.18±10.49) Gy, and (5.44±3.10) Gy vs.(6.25±3.26) Gy, as well as (12.70±7.08)% vs.(14.47±8.11)%, all P<0.05). Monitor units did not significantly differ between two plans ((710.67±163.72) MU vs.(707.53±155.89) MU, P>0.05). Conclusions:The automatic planning method using VMAT for PLC radiotherapy based on predicting the feasibility DVH enhances the quality for PLC plans, especially in terms of normal liver sparing. Besides, it also has advantages for the protection of the intestine, whole lung and heart.
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Intestinal injury is an important toxic response during radiation therapy of pelvic tumors. With the widespread use of precision radiotherapy techniques such as intensity modulated radiation therapy (IMRT), the dose exposed to normal tissues and organs has been significantly reduced. However, the toxic response of the bowel still limits the increase of the dose to the target volume. Therefore, the protection of important organs at risk (OAR), such as the bowel, becomes more and more important while giving adequate irradiated dose to the target volume. Most current studies used loop to contour bowel. For patients who underwent IMRT, the meaningful dose-volume predictors of grade 2 acute intestinal adverse events using bowel loop (small loop + big bowel) delineation included V45 Gy < 50 cm 3,V50 Gy < 13 cm 3, and V55 Gy < 3 cm 3, and the corresponding predicators using bowel bag delineation were V40 Gy < 170 cm 3,V45 Gy < 100 cm 3, and V50 Gy < 33 cm 3.
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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
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Objective@#To study the relationship between the dose-volume indexes and acute toxicity of intrathoracic stomach in esophageal cancer patients receiving radiotherapy after esophagectomy.@*Methods@#A total of 104 patients treated with postoperative radiotherapy followed by radical esophagectomy were enrolled. The dose-volume indexes of intrathoracic stomach were collected from treatment planning system. The ROC curve and logistic regression were performed to analyze the relationship between acute toxicity of intrathoracic stomach and clinical parameters, dose-volume indexes.@*Results@#A total of 29 patients (27.88 %) suffered from grade 2 or above acute toxicity. The ROC curve analysis showed that the dose-volume indexes including Dmax, Dmean, L5-L45 and V5-V50were associated with occurrence of grade 2 or above acute toxicity. The univariate analysis showed that location, Dmax, Dmean, L5-L45 and V5-V50 were significantly correlated with the incidence of grade 2 or above acute toxicity (P<0.05). The multivariate analysis showed that location, L5 and V35 were independent factors for incidence of grade 2 or above acute toxicity. The ROC curve analysis showed that cut-off values of L5 and V35 were 14.00 cm and 44.00%, respectively. And the rates of Grade 2 or above acute toxicity were 20.00% for L5>14.00 cm and 38.64% for L5≥14.00 cm (χ2=4.473, P<0.05), 14.08% for V35<44.00% and 57.58% for V35≥44.00% (χ2=7.263, P<0.05), respectively. The incidence of grade 2 or above acute toxicity was significantly higher in post-mediastinum stomach group than the other two groups (χ2=12.881, P<0.05).@*Conclusions@#Dose-volume index may be indicator to predict acute toxicity of intrathoracic stomach. It is recommended that post-mediastinum stomach should be chosen carefully if esophageal cancer patients require postoperative radiotherapy.
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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
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Objective To study the relationship between the dose-volume indexes and acute toxicity of intrathoracic stomach in esophageal cancer patients receiving radiotherapy after esophagectomy.Methods A total of 104 patients treated with postoperative radiotherapy followed by radical esophagectomy were enrolled.The dose-volume indexes of intrathoracic stomach were collected from treatment planning system.The ROC curve and logistic regression were performed to analyze the relationship between acute toxicity of intrathoracic stomach and clinical parameters,dose-volume indexes.Results A total of 29 patients (27.88 ％) suffered from grade 2 or above acute toxicity.The ROC curve analysis showed that the dose-volume indexes including D D L5-L45 and V5-V50were associated with occurrence of grade 2 or above acute toxicity,The univariate analysis showed that location,D D L5-L45 and V5-V50 were significantly correlated with the incidence of grade 2 or above acute toxicity (P＜0.05).The multivariate analysis showed that location,L5 and V35 were independent factors for incidence of grade 2 or above acute toxicity.The ROC curve analysis showed that cut-off values of L5 and V35 were 14.00 cm and 44.00％,respectively.And the rates of Grade 2 or above acute toxicity were 20.00％ for L5＞ 14.00 cm and 38.64％ for L5 ≥ 14.00 cm (x2 =4.473,P＜0.05),14.08％ for V35＜44.00％ and 57.58％ for V35 ≥44.00％ (x2 =7.263,P＜0.05),respectively.The incidence of grade 2 or above acute toxicity was significantly higher in post-mediastinum stomach group than the other two groups (x2 =12.881,P＜0.05).Conclusions Dosevolume index may be indicator to predict acute toxicity of intrathoracic stomach.It is recommended that post-mediastinum stomach should be chosen carefully if esophageal cancer patients require postoperative radiotherapy.
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Objective To evaluate the feasibility of utilizing dose-volume histogram (DVH) prediction models of organs at risk (OARs) to deliver automatic treatment planning of prostate cancer.Methods The training set included 30 cases randomly selected from a database of 42 cases of prostate cancer receiving treatment planning.The bladder and rectum were divided into sub-volumes (Ai) of 3 mm in layer thickness according to the spatial distance from the boundary of planning target volume (PTV).A skewed normal Gaussian function was adopted to fit the differential DVH of Ai,and a precise mathematical model was built after optimization.Using the embedded C++ subroutine of Pinnacle scripa,ahe volume of each Ai of the remaining validation set for 12 patients was obtained to predict the DVH parameters of these OARa,ahich were used as the objective functions to create personalized Pinnacle script.Finalla,automatic plans were generated using the script.The dosimetric differences among the original clinical plannina,aredicted value and the automatic treatment planning were statistically compared with paired t-test.Results DVH residual analysis demonstrated that predictive volume fraction of the bladder and rectum above 6 000 cGy were lower than those of the original clinical planning.The automatic treatment planning significantly reduced the V70,V60,V50 of the bladder and the V70 and V60 of the rectum than the original clinical planning (all P＜0.05),the coverage and conformal index (CI) of PTV remained unchangea,and the homogeneity index (HI) was slightly decreased with no statistical significance (P＞ 0.05).Conclusion The automatic treatment planning of the prostate cancer based on the DVH prediction models can reduce the irradiation dose of OARs and improve the treatment planning efficiency.
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Radiation-induced lung injury (RILI) is a common complication after radiotherapy for thoracic tumors.It is one of the most urgent problems to explore the optimal animal model and evaluate the effect for basic research and drug intervention along with the extensive studies of radiation pneumonia.By reviewing the literatures published in recent 10 years,the selection of irradiation site,determination of irradiation dosage,irradiation method and effect evaluation were statistically compared among different RILI animal models,aiming to explore a stable method of establishing the animal model with RILI and identify a definite effect mechanism.It provides a reliable approach for basic research and drug development to prevent and mitigate the incidence and development of RILI.
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Objective To study the application value of radiotherapy optimization after modified radical mastectomy.Methods From January 2012 to January 2015,one hundred and twelve patients treated with modified radical mastectomy in Taizhou Cancer Hospital were enrolled and divided randomly into group A,B and C.40 patients in group A received modulated radiation therapy(MRT) with 2.0Gy/f,25 times,DT50Gy for 33-35d;35 cases in group B received concurrent chemoradiotherapy with MRT and 37 cases in group C received concurrent chemoradiotherapy with large segmentation scheme of 2.66Gy/f,16 times,DT42.56Gy for 22-24d.The recurrence rate,survival rate and the incidence of acute and chronic radiation injury of the 3 groups were compared.The parameters of V5,V10,V20 and V30 of ipsilateral lung was recorded by dose volume histogram(DVH).Results The total recurrence rate in group C was significantly lower than that of the other two groups (16.2％(6/37) vs.28.6％(10/35) vs.42.5％(17/40),x2 =6.409,P=0.041),while the total survival rate was significantly higher than that of the other two groups (89.2％ (33/37) vs.77.1％ (27/35) vs.65.0％ (26/40),x2 =6.313,P =0.043),and there was no significant difference in the local recurrence and distant metastasis rate in the 3 groups (P＞0.05).The incidence of total radiation injury in group C was lower than that of the other two groups (21.6％ (8/37) vs.42.9％ (15/35) vs.50％ (20/40),x2 =6.973,P =0.031),and there was no significant difference in the incidence of acute and chronic injury and the grade of injury in the 3 groups (P＞0.05).The values of VS,V10,V20 and V30 increased gradually in the 3 groups.The V5 and V10 in group C were significantly higher than those of the other two groups ((32.9 ± 7.4) ％ vs.(17.5 ± 5.9) ％ vs.(16.8 ± 6.4) ％,F =18.625,P=0.000,(42.4±7.3)％ vs.(39.3±5.8)％ vs.(35.5±6.0)％,F=15.624,P=0.000),and there was no significant difference in V20 and V30 among the three groups (P＞ 0.05).Conclusion The combination of concurrent chemoradiotherapy and breast cancer after modified radical mastectomy is of great value in improving prognosis and reducing radiation damage.
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There is a high risk of myelosuppression in pelvic malignant tumors during concurrent chemoradiotherapy. The dose-volume relationship of pelvic exposed bone marrow( bone) is related to acute hematological toxicity during radiotherapy and chemotherapy,but lacks recognized parameters in this respect. The hematopoietic capacity of the bone marrow(bone)in different parts of the pelvic cavity is heterogeneous,and the pelvic bone marrow near the central axis has the strongest hematopoietic capacity,namely functional bone marrow. The relationship between dose-volume parameters of pelvic functional bone marrow and acute hematologic toxicity during chemoradiotherapy of pelvic malignant tumors may be the future direction.
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Objective@#To evaluate the effect of tumor shape and location on pulmonary dose-volume parameters by intensity-modulated radiation therapy (IMRT) in patients with non-small cell lung cancer (NSCLC), aiming to provide a reference basis for establishing limits of the pulmonary dose-volume parameters during IMRT.@*Methods@#Clinical data of 208 NSCLC patients undergoing radical IMRT from June 2009 to June 2016 were retrospectively analyzed. According to the tumor shape and location, 208 cases were divided into the vertical bar group (n=127) and the horizontal bar group (n=81), the superior lung group (n=103) and the inferior lung group (n=105). Regression model curve was used to evaluate the effect of tumor shape and location upon the common pulmonary dose-volume parameters(V5, V20, MLD, AVS5 and AVS20).@*Results@#In all groups, the fitting curves of V5, V20 and MLD were manifested in the quadratic equation pattern, and AVS5 and AVS20 in the logarithmic equation manner. In the vertical bar group, the V5(P=0.015), V20(P=0.047) and MLD (P=0.012) were significantly higher, whereas the AVS5(P=0.044) was significantly lower compared with those in the horizontal bar group. No statistical significance was observed in AVS20 between two groups (P=0.490). The tumor location exerted significant effect upon V5 alone (P=0.009).@*Conclusions@#When the tumors presents in the vertical bar shape, the limits of the common lung dose-volume parameters are likely to exceed those of tumors in the vertical bar shape. Lung tumors located in the inferior lobe exerts a more significant effect upon the low-dose region volume compared with the tumors in the superior lobe.