Single-Cell Mapping of Brain Myeloid Cell Subsets Reveals Key Transcriptomic Changes Favoring Neuroplasticity after Ischemic Stroke / 神经科学通报·英文版

Interactions between brain-resident and peripheral infiltrated immune cells are thought to contribute to neuroplasticity after cerebral ischemia. However, conventional bulk sequencing makes it challenging to depict this complex immune network. Using single-cell RNA sequencing, we mapped compositional and transcriptional features of peri-infarct immune cells. Microglia were the predominant cell type in the peri-infarct region, displaying a more diverse activation pattern than the typical pro- and anti-inflammatory state, with axon tract-associated microglia (ATMs) being associated with neuronal regeneration. Trajectory inference suggested that infiltrated monocyte-derived macrophages (MDMs) exhibited a gradual fate trajectory transition to activated MDMs. Inter-cellular crosstalk between MDMs and microglia orchestrated anti-inflammatory and repair-promoting microglia phenotypes and promoted post-stroke neurogenesis, with SOX2 and related Akt/CREB signaling as the underlying mechanisms. This description of the brain's immune landscape and its relationship with neurogenesis provides new insight into promoting neural repair by regulating neuroinflammatory responses.

CBCT-based synthetic CT generated using CycleGAN with HU correction for adaptive radiotherapy of nasopharyngeal carcinoma.

This study aims to utilize a hybrid approach of phantom correction and deep learning for synthesized CT (sCT) images generation based on cone-beam CT (CBCT) images for nasopharyngeal carcinoma (NPC). 52 CBCT/CT paired images of NPC patients were used for model training (41), validation (11). Hounsfield Units (HU) of the CBCT images was calibrated by a commercially available CIRS phantom. Then the original CBCT and the corrected CBCT (CBCT_cor) were trained separately with the same cycle generative adversarial network (CycleGAN) to generate SCT1 and SCT2. The mean error and mean absolute error (MAE) were used to quantify the image quality. For validations, the contours and treatment plans in CT images were transferred to original CBCT, CBCT_cor, SCT1 and SCT2 for dosimetric comparison. Dose distribution, dosimetric parameters and 3D gamma passing rate were analyzed. Compared with rigidly registered CT (RCT), the MAE of CBCT, CBCT_cor, SCT1 and SCT2 were 346.11 ± 13.58 HU, 145.95 ± 17.64 HU, 105.62 ± 16.08 HU and 83.51 ± 7.71 HU, respectively. Moreover, the average dosimetric parameter differences for the CBCT_cor, SCT1 and SCT2 were 2.7% ± 1.4%, 1.2% ± 1.0% and 0.6% ± 0.6%, respectively. Using the dose distribution of RCT images as reference, the 3D gamma passing rate of the hybrid method was significantly better than the other methods. The effectiveness of CBCT-based sCT generated using CycleGAN with HU correction for adaptive radiotherapy of nasopharyngeal carcinoma was confirmed. The image quality and dose accuracy of SCT2 were outperform the simple CycleGAN method. This finding has great significance for the clinical application of adaptive radiotherapy for NPC.

Evaluation of auto-planning in VMAT for locally advanced nasopharyngeal carcinoma.

The aim of this study is to demonstrate the feasibility of a commercially available Auto-Planning module for the radiation therapy treatment planning for locally advanced nasopharyngeal carcinoma (NPC). 22 patients with locally advanced NPC were included in this study. For each patient, volumetric modulated arc therapy (VMAT) plans were generated both manually by an experienced physicist and automatically by the Auto-Planning module. The dose distribution, dosimetric parameters, monitor units and planning time were compared between automatic plans (APs) and manual plans (MPs). Meanwhile, the overall stage of disease was factored into the evaluation. The target dose coverage of APs was comparable to that of MPs. For the organs at risk (OARs) except spinal cord, the dose parameters of APs were superior to that of MPs. The Dmax and V50 of brainstem were statistically lower by 1.0 Gy and 1.32% respectively, while the Dmax of optic nerves and chiasm were also lower in the APs (p < 0.05). The APs provided a similar or superior quality to MPs in most cases, except for several patients with stage IV disease. The dose differences for most OARs were similar between the two types of plans regardless of stage while the APs provided better brainstem sparing for patients with stage III and improved the sparing of the parotid glands for stage IV patients. The total monitor units and planning time were significantly reduced in the APs. Auto-Planning is feasible for the VMAT treatment planning for locally advanced NPC.

Automated Intensity Modulated Radiation Therapy Treatment Planning for Cervical Cancer Based on Convolution Neural Network.

PURPOSE: To develop and evaluate an automatic intensity-modulated radiation therapy (IMRT) program for cervical cancer, including a Convolution Neural Network (CNN)-based prediction model and an automated optimization strategy. METHODS: A CNN deep learning model was trained to predict a patient-specify set of IMRT objectives based on overlap volume histograms (OVH) and high-quality plan of previous patients. A total of 140 cervical cancer patients were enrolled in this study, including 100 patients in the training set, 20 patients in the validation set and 20 patients in the testing set. The input of this model was OVH data and the output were values of IMRT plan objectives. For patients in the testing set, the set of planning objectives were predicted by the CNN model and used to automatically generate IMRT plans. Meanwhile, manual plans of these patients were generated by 1 beginner planner and 1 senior planner respectively. Finally, dose distribution, dosimetric parameters and planning time were analyzed. In addition, the 3 types of plans were blinded compared and ranked by an experienced oncologist. RESULTS: There were almost no statistically differences among these 3 types of plans in target coverage and dose conformity. Dose homogeneity were slightly decreased while the average dose and parameters for most organs-at-risk (OARs) were decreased in automatic plans. Especially in comparison with manual plans by the beginner planner, V40 of bladder and rectum decreased 6.3% and 12.3%, while mean dose of rectum and marrow were 1.1 Gy and 1.8 Gy lower with automatic plans (either P < 0.017). In the blinded comparison, automatic plans were chosen as best plan in 14 cases. CONCLUSIONS: For cervical cancer, automatic IMRT plans optimized from the CNN generated objectives have superior dose sparing without compromising of target dose. It significantly reduced the planning time.

Feasibility of automatic IMRT planning for cervical cancer based on a database of previously-treated patients / 中华放射肿瘤学杂志

Objective To develop and evaluate an automatic intensity-modulated radiation therapy (IMRT) program for cervical cancer based on a database of overlap volume histogram (OVH) and high-quality cervical IMRT plans for previously-treated patients.Methods A database consisting of high-quality IMRT plans and OVHs from 200 cervical cancer patients was established.OVHs of another 26 cervical cancer patients were converted into gray level images to calculate the image similarity compared with those from the database.The planning optimization function of the patients from the database with the highest image similarity was selected and inherent Pinnacle3 scripts were utilized to automatically generate IMRT plan.Finally,the dosimetric parameters,plan quality and design time were statistically compared between the automatic and manual plans.Results The target coverage,conformity index and homogeneity index did not significantly differ between two plans (all P＞0.05).The V40,V45 and mean dose for the rectum in the automatic plans were significantly decreased by 6.1％,1.3％ and 50.7 cGy than those in the manual plans (all P＜0.05).Compared with the manual plans,the mean dose for the intestine and femur in the automatic plans were significantly reduced by 31.7 cGy and 188.9 cGy (both P＜0.05),whereas the mean dose for the ilium was slightly decreased by 92.3 cGy in the automatic plans (P＞ 0.05).The plan design time was shortened by 71％ in the automatic plans.Conclusions The automatic IMRT plans based on a database of OVH and high-quality IMRT plans can not only significantly shorten the plan design time,but also reduce the irradiated dose of normal tissues without compromising the target coverage and conformity index.

Feasibility of automatic IMRT planning for cervical cancer based on a database of previously-treated patients / 中华放射肿瘤学杂志

Objective@#To develop and evaluate an automatic intensity-modulated radiation therapy (IMRT) program for cervical cancer based on a database of overlap volume histogram (OVH) and high-quality cervical IMRT plans for previously-treated patients.@*Methods@#A database consisting of high-quality IMRT plans and OVHs from 200 cervical cancer patients was established. OVHs of another 26 cervical cancer patients were converted into gray level images to calculate the image similarity compared with those from the database. The planning optimization function of the patients from the database with the highest image similarity was selected and inherent Pinnacle3 scripts were utilized to automatically generate IMRT plan. Finally, the dosimetric parameters, plan quality and design time were statistically compared between the automatic and manual plans.@*Results@#The target coverage, conformity index and homogeneity index did not significantly differ between two plans (all P>0.05). The V40, V45 and mean dose for the rectum in the automatic plans were significantly decreased by 6.1%, 1.3% and 50.7 cGy than those in the manual plans (all P<0.05). Compared with the manual plans, the mean dose for the intestine and femur in the automatic plans were significantly reduced by 31.7 cGy and 188.9 cGy (both P<0.05), whereas the mean dose for the ilium was slightly decreased by 92.3 cGy in the automatic plans (P>0.05). The plan design time was shortened by 71% in the automatic plans.@*Conclusions@#The automatic IMRT plans based on a database of OVH and high-quality IMRT plans can not only significantly shorten the plan design time, but also reduce the irradiated dose of normal tissues without compromising the target coverage and conformity index.

Application of autosegmentation software in esophageal cancer / 中华放射医学与防护杂志

Objective To evaluate the geometric and dosimetric accuracy of autosegmentation software for contouring the organ-at-risk ( OAR) of esophageal cancer, and discuss its clinical feasibility. Methods A total of 10 patients were enrolled, and single and multi-template were adopted respectively to auto-delineate corresponding OARs on target CT images based on image registration. The geometric consistency including volume difference (ΔV) , dice similarity ( DSC) and position difference (Δx, Δy,Δz) between the two autosegmentation method and manual were compared using Wilcoxon signed-rank test. And the correlation between DSC and OAR volume was analyzed. In addition, to evaluate the clinical feasibility of autosegmentation, the dose distributions of all OARs were compared using Friedman test. Results The average DSC of all OARs obtained by single and multi-template were 0.82 ± 0.17 and 0.92 ± 0.54, respectively, with statistically significant difference (Z= -2.803- -2.497, P<0.05). A positive correlation between DSC of the autosegmentation and OAR volume was found by spearman analysis, and the single-template was not good enough for the spinal cord with smaller volume. The positional deviations of multi-template group were less than 0.5 cm in three directions, which were better than single-template group. The main dosimetric indexes of single-template and multiple-template were similar to manual coutours. V20 of whole lung were 23.2％, 22.4％ and 22.1％, Dmeanof whole lung were (11.3 ±4.0), (11.1 ±4.5) and (11.0 ±4.3) Gy, Dmaxof spinal cord were (40.3 ±4.8), (38.2 ±6.7) and (39.4 ± 5.3) Gy, respectively, and V30 of heart were 16.0％, 15.8％ and 15.5％, respectively. There was no statistical difference between the three methods (P>0.05), and all of the dosimetric indexes were in line with the requirements of clinical dose limits. Conclusions The autosegmentation software can achieve satisfactory precision for the OARs of the esophageal cancer patients, and the multi-template method is better than the single-template, which is more suitable for clinical application.

Dosimetric comparison of combined intracavitary/interstitial brachytherapy planning using three different kinds of optimization methods in locally advanced cervical cancer / 中华放射医学与防护杂志

Objective To compare and analyze the dosimetric discrepancy of combind intracavitary/interstitial brachytherapy using three different kinds of optimization method in locally advanced cervical cancer.Methods Totally 20 cases of locally advanced cervical cancer were selected and divided into three groups according to different optimization method which include manual optimization group (MO) based on graphical optimization,inverse planning simulated annealing (IPSA 1)based on simulated annealing optimization algorithm,IPSA 2 based on IPSA 1 with limitation on maximum dose of target.The dose volume histogram parameters of the targets (V200,V150,V100,D100,D90,HI) and the OARs(D0.1 cm3,D1 cm3 and D2 cm3) were analyzed.Results For CTV,compared with MO,there was no significantly statistical difference in D100between IPSA 1 and IPSA 2(P ＞ 0.05).However,V200,V150,V100 and HI for ISPA1 were better than for ISPA2 (t =-3.422-9.910,P ＜ 0.05).In addition,V100 and D100 in ISPA1 were better than in ISPA2 (t =7.238,5.032,P ＜0.05).For OARs,D0.1 cm3,D1 cm3 and D2 cm3 in rectum,bladder,sigmoid colon of both ISPA 1 and ISPA 2 were dramatically lower than those of MO (t =2.235 5.819,P ＜ 0.05),without significantly statistical difference found between ISPA1 and ISPA2.Conclusions For combined intracavitary/interstitial brachytherapy in locally advanced cervical cancer,all treatment plans based on three different kinds of optimization methods can meet the clinical need.Moreover,inverse optimization can ensure dose coverage over target and reduce maximum dose of rectum,bladder and sigmoid colon.

Effect of locking compression plate and anatomical plate internal fixation in treatment of closed tibial Pilon fracture and its influence on lower limb functional rehabilitation / 临床外科杂志

Objective To investigate the effect of locking compression plate(LCP)and anatomi-cal plate(AP)in the treatment of closed tibial Pilon fracture and its influence on lower limb functional re-habilitation.Methods A total of 82 patients with closed tibial Pilon fractures were randomly divided into LCP internal fixation group(LCP group,n=41)and AP internal fixation group(AP group,n=41).The perioperative indexes and the incidence of postoperative complications were compared between the two groups.The ankle function was evaluated by American Orthopaedic Foot & Ankle Society Ankle Hindfoot Scale(AOFAS-AHS),the lower limb function was evaluated by Lysholm scale,the serum levels of inter-leukin-1β(IL-1β)and interleukin-6(IL-6)were detected.Results The intraoperative blood loss,opera-tion time,hospitalization time,first ground time,fracture healing time were(103. 34 ± 11. 34)ml, (47.65 ± 7.89)min,(9.01 ± 2.23)d,(5.31 ± 1.27)d,(16.23 ± 2.12)weeks in LCP group respective-ly,the AP group were(132.25 ± 34.41)ml,(60.54 ± 11.23)ml,(11.43 ± 2.57)d,(6.23 ± 1.56)d, (23.12 ± 3.31)weeks,respectively.The LCP group were significantly lower than AP group(P<0.05);The excellent rate of ankle function of LCP group was 95.12%,significantly higher than 82.93% in the AP group(P<0.05);The incidence of postoperative complications was 4.88% in the LCP group,which was significantly lower than 29.27% in the AP group(P<0.05);At 3,6 and 12 months after operation, the AOFAS-AHS scores in the LCP group were(69.52 ± 4.18)points,(78.89 ± 6.73)points and (87.23 ± 6.34)points respectively,the AP group were(65.09 ± 4.45)points,(70.13 ± 5.34)points and (76.69 ± 5.91)points respectively,the LCP group were significantly higher than AP group(P<0.05);At 3,6 and 12 months after operation,the Lysholm scores were(77.12 ± 6.43)points,(82.12 ± 7.81)points and(86.19 ± 8.11)points in LCP group,AP group were(67.25 ± 5.56)points,(72.21 ± 7.23)and (77.12 ± 7.54)points,the LCP group was significantly higher than AP group(P<0.05).At 3 d and 4 weeks after operation,the serum levels of IL-1β in LCP group were(0.37 ± 0.09)pg/ml,(0.19 ± 0.06) pg/ml,while in AP group were(0.45 ± 0.13)pg/ml,(0.27 ± 0.09)pg/ml;the serum levels of IL-6 in LCP group were(201.23 ± 30.12)ng/L,(102.23 ± 25.21)ng/L,while in AP group were(246.71 ± 41.23)ng/L,(158.95 ± 25.21)ng/L.The AP group were significantly lower than those in AP group(P<0.05).Conclusion LCP and AP in treatment of closed tibial Pilon fractures have a significant effect,but LCP can reduce the surgical trauma,shorten the operation time and postoperative recovery time,to a cer-tain extent,improve the ankle and lower limb function,and reduce the postoperative fixation fracture heal-ing and other complications.

Dosimetric sensitivity with MU and MLC errors in IMRT versus VMAT plan for nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Objective To simulate the possible systematic delivery errors introduced by monitor units ( MU) and multi-leaf collimator ( MLC) in radiotherapy plans for nasopharyngeal carcinoma ( NPC) , and to analyze the dosimetric sensitivity of static intensity-modulated radiotherapy ( IMRT ) and volumetric modulated arc therapy ( VMAT) with these errors. Methods Five IMRT plans were replanned using VMAT modality with the same physical parameters, and then MU errors of 125%, 250%, and 5. 00% were introduced into IMRT and VMAT plans. Meanwhile, to simulate leaf position errors during delivery, MLC position errors (025 mm, 050 mm, 100 mm, 150 mm, and 200 mm) were introduced by modifying the original plan documents. The types of MLC errors were as follows:( 1) the MLC banks moved in the same direction;( 2) the MLC banks moved in opposing directions ( expand or contract the MLC gaps ) . The differences in dosimetric sensitivity introduced by MU and MLC errors between IMRT and VMAT plans for NPC were calculated by linear regression analysis. Results With the increase in MU errors, the doses to target and organs at risk ( OARs) of IMRT and VMAT plans increased in a linear way, and met R2=0992-1000( P<005) . For MLC errors, the average dosimetric sensitivity for target and OARs of IMRT and VMAT were-026%/mm and-065%/mm in case of offset errors, 487%/mm and 868%/mm in case of expansion errors, and -604%/mm and -988%/mm in case of indentation errors. In addition, the dosimetric sensitivity with the three types of MLC errors was greater for VMAT plan than for IMRT plan. ConclusionsMU and MLC errors have a significant effect on the dose distribution of IMRT, and particularly VMAT, for NPC. It is important to execute routine quality assurance of MLC to ensure accurate radiotherapy.

Dosimetric sensitivity with MU and MLC errors in IMRT versus VMAT plan for nasopharyngeal carcinoma / 中华放射肿瘤学杂志

Objective To simulate the possible systematic delivery errors introduced by monitor units ( MU) and multi-leaf collimator ( MLC) in radiotherapy plans for nasopharyngeal carcinoma ( NPC) , and to analyze the dosimetric sensitivity of static intensity-modulated radiotherapy ( IMRT ) and volumetric modulated arc therapy ( VMAT) with these errors. Methods Five IMRT plans were replanned using VMAT modality with the same physical parameters, and then MU errors of 125%, 250%, and 5. 00% were introduced into IMRT and VMAT plans. Meanwhile, to simulate leaf position errors during delivery, MLC position errors (025 mm, 050 mm, 100 mm, 150 mm, and 200 mm) were introduced by modifying the original plan documents. The types of MLC errors were as follows:( 1) the MLC banks moved in the same direction;( 2) the MLC banks moved in opposing directions ( expand or contract the MLC gaps ) . The differences in dosimetric sensitivity introduced by MU and MLC errors between IMRT and VMAT plans for NPC were calculated by linear regression analysis. Results With the increase in MU errors, the doses to target and organs at risk ( OARs) of IMRT and VMAT plans increased in a linear way, and met R2=0992-1000( P<005) . For MLC errors, the average dosimetric sensitivity for target and OARs of IMRT and VMAT were-026%/mm and-065%/mm in case of offset errors, 487%/mm and 868%/mm in case of expansion errors, and -604%/mm and -988%/mm in case of indentation errors. In addition, the dosimetric sensitivity with the three types of MLC errors was greater for VMAT plan than for IMRT plan. ConclusionsMU and MLC errors have a significant effect on the dose distribution of IMRT, and particularly VMAT, for NPC. It is important to execute routine quality assurance of MLC to ensure accurate radiotherapy.

Dosimetric comparison of TomoDirect and TomoHelical modalities in Tomotherapy system for left-breast cancer radiotherapy after breast-conserving surgery / 中华放射医学与防护杂志

Objective To compare the dosimetric difference among plans designed by 4-field,6-field TomoDirect and TomoHelical techniques in Tomotherapy system for left-breast cancer patients with radiotherapy after breast-conserving surgery.Method A total of 16 patients with left-breast cancer following breast-conserving surgery and intensity-modulated radiation therapy were enrolled in this retrospective study.The 4-field TomoDirect (TD4),6-field TomoDirect (TD6),and TomoHelical (TH) techniques were applied to design simulation plans in tomotherapy system for each patient,respectively.The differences of dose distribution and treatment parameters were analyzed in this study.Results Three plans all met the clinical requirement.Thereinto,TD4 was superior to TH in the dose limitation of organs at risk (OARs),especially the max dose of cord and right-breast,thc 5 Gy radiation volume of lung,and the mean dose of heart(F =595.60,129.24,60.44,65.37,P ＜ 0.05),but inferior to TH in dose homogeneity (HI) and conformity (CI) (F =2.78,60.93,P ＜ 0.05).However,TD6 improved TD4's HI and CI when delivered the lower OARs dose compared to TH.Meanwhile,the number of monitor units was less in TD technique and reduced the treatment times (F =24.89,3.75,P ＜ O.05).Conclusions For the radiotherapy of left-breast cancer patients after breast-conserving surgery,TD6 technique appeared to be superior,with the lower radiation dose of OARs compared to TH technique,and the better target's HI and CI in comparison with TD4 technique,especially in patients with early stage breast cancer.

The feasibility study of atlas-based autosegmentation (ABAS) software in head-and-neck cancer / 中华放射肿瘤学杂志

Objective To test and evaluate the geometric accuracy of delineation of organs at risk ( OARs) in head and neck cancer using an atlas?based autosegmentation ( ABAS) software. Methods The atlases for the ABAS software was generated using images from 40 patients with head and neck cancer undergoing intensity?modulated radiotherapy. The software was tested in 40 new patients. Automatic delineation of OARs was carried out on computed tomography images by single?( one to one ) and multi?template ( ten to one) approaches. In order to evaluate the feasibility of the automatic delineation in clinical application, differences in volume (ΔV%), position (Δx,Δy, andΔz), conformability (sensitivity ( Se ), specificity ( Sp ) , and dice similarity coefficient ( DSC) ) , and delineation time were assessed between the automatic and manual delineation. The comparison between the two automatic delineation approaches was made by paried t test. Results For all OARs, the multi?template automatic delineation achieved a significantly smaller mean ΔV% value and a significantly larger mean DSC value than the single?template automatic delineation (-0.02%± 0?29% vs. -0.16%± 0?41%, P<0?05;0.74± 0?16 vs. 0.68± 0?20, P<0?05);the position differences between two automatic delineation approaches were less than 0?4 cm in all three directions except for the temporal lobe, lower jaw, and spinal cord;in the receiver operating characteristic curve defined by Se versus 1-Sp , the data points were all within the first quadrant except for the optic nerve and chiasm;automatic delineation saved 42%?72% of time compared with manual delineation. Conclusions The ABAS software achieves satisfactory results of automatic delineation for most of OARs in patients with head and neck cancer. The multi?template automatic delineation, particularly, has better outcomes than the single?template one. In addition, it greatly shortens the time the clinicians spend on delineation of OARs.

Dosimetric study of different intensity-modulated modalities in the radiotherapy for mid and upper thoracic esophageal carcinoma / 中华放射医学与防护杂志

Objective To compare the static intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) for mid and upper thoracic esophageal cancer.Method The data of twenty esophageal cancer patients were retrospectively re-planned with VMAT(single arc and double arcs) modality using Pinnacle treatment plan system.Five of these patients were selected again to simulate single arc plans with different segment intervals (4°,3°,2°) and re-planned on other treatment planning systems (Monaco and MasterPlan).Differences of dose distribution and treatment parameters were compared.Results In comparison to IMRT and single-VMAT (S-VMAT),Double-VMAT (D-VMAT) significantly improves the dosimetric parameters for targets(P ＜ 0.05),dose homogeneity(P ＜ 0.05) and conformity(P ＜ 0.05).Though VMAT plans were slightly better than IMRT in reducing the doses to the organs at risk (OARs),no advantage was observed in the low-dose protection of lung and E-P (P ＜ 0.05).For the VMAT plans with different segment intervals,lower OAR doses were observed using an interval of 2°(P ＜ 0.05),except for the mean dose of the heart.For the VMAT plans on different treatment planning systems,Monaco-based plans protected OARs better (P ＜ 0.05).The number of monitor units (MU) and treatment time were less in VMAT cases.Conclusions VMAT plans perform better in target coverage,dose homogeneity and conformity,and can reduce the radiation dose to the spinal cord,lungs,heart and other normal tissue than IMRT plans.The VMAT plan quality could be further improved by using double arcs and smaller segment interval.Monaco-based plans provide better OAR protections under the same conditions of physical and optimization parameters.

Dosimetric comparison of three intensity-modulate radiation therapy treatment modules for nasopharyngeal carcinoma / 中华放射医学与防护杂志

Objective To compare the dosimetric differences of fixed field intensity-modulated radiation therapy(IMRT),volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT) for nasopharyngeal carcinoma (NPC) patients.Methods Eighteen NPC patients previously treated with VMAT were retrospectively included and re-planned using HT and IMRT (7 fields) techniques utilizing the same dose prescription and optimization objectives.The following parameters were compared across the three types of plans:homogeneity index (HI),conformity index (CI),maximum dose (Dmax) and mean dose (Dmean) of targets ; the Dmax and Dmean of organs at risk (OARs) ; the doses and volumes of volume of interest; the treatment delivery time and monitor units (MU).Results Clinically acceptable target coverage could be achieved by IMRT,VMAT and HT plans.The HT plans were the best yet IMRT plans were the worst in HI and CI of targets.IMRT imposed highest doses to OARs while HT deposited least doses to the spinal cord,brainstem and parotid.However,the VMAT plans displayed the lowest doses on optic nerves,chiasma and lens while highest doses were found in IMRT plans.The average delivery time per fraction of IMRT (8.0±0.5) min were more than that of HT (7.4 ±0.9) min and VMAT (3.9 ±0.1) min plans.The MUs of IMRT plans (711.4 ±78.7) were larger than that of VMAT plans (596.4 ±33.7).Conclusions Three types of plans can all achieve the clinical dosimetric demands,but HT has the best performance on CI and HI.VMAT is most efficient regarding the delivery time and total MUs.

Significance of primary tumor volume on prognosis in nasopharyngeal carcinoma treated by Intensity-modulated radiotherapy / 中华放射肿瘤学杂志

ObjectiveTo analyze the correlation between primary tumor volume (PTV) and prognosis of nasopharyngeal carcinoma ( NPC ) treated by intensity-modulated radiotherapy ( IMRT ).Methods330 NPC patients treated by IMRT were included.Pretreatment computerized tomography image were input into tree-dimensional treatment-planning system,in which the primary tumor volume were calculated automatically.The receiver operating characteristic curve was used to determine the best cut-off point of PTV.Within the framework of UICC 2002 T stage,The PTV was divided into four groups:V1 ＜ 10cm3,V2 10-25 cm3,V3 ＞ 25-50 cm3 and V4 ＞ 50 cm3.Kaplan-Meier and Logrank test was used to analyze the survival,Cox proportion risk regression model were used to analysis the correlation between PTV and prognosis.ResultsThe mean PTV for all NPC patients was ( 34.2 ± 27.1 ) cm3 with the range of 0.4- 153.7 cm3.The 3-year overall survival for V1,V2,V3 and V4 stage were 88.6％,90.0％,91.2％ and 74.2％,respectively (x2 =12.83,P =0.005 ).There was no significant difference among V1,V2 and V3in terms of overall survival ( x2 =1.96,P =0.376).The 3-year distant metastasis-free survival and diseasesfree survival or overall survival were decrease in PTV ＞50 cm3 and PTV≤50 cm3 (77.4％:89.9％,x2 =7.24,P=0.007and 64.5％:85.1％,x2 =13.95,P=0.000 or 74.2％:90.3％,x2 =11.76,P=0.001).Multivariate analysis revealed that PTV was a adverse prognostic factors for overall survival (x2 =0.00,P =2.580).ConclusionOur data showed that the primary tumor volume had significantly impacted on the prognosis of NPC patients treated by intensity modulated radiotherapy.

Dosimetric study of influence of intensity modulated radiotherapy for nasopharyngeal carcinoma on hippocampal formation / 中华放射医学与防护杂志

Objective To evaluate the dosimetric characteristics of hippocampal formation (HF) in the intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC).Methods Fifty-nine NPC patients underwent IMRT.Simultaneous integrated boost technology was used to determine the doses for the target areas.The dose ranges of the HF were collected by dose-volume histogram.The influence of T stage on the exposure doses ( Dmax,Dmean,D20,V10,V20,V30,and V40 ) were compared.Results The maximum dose for the HF (Dmax) ranged from 11.1 to 78.2 Gy(F =24.2,P ＜0.05) and the Dmean ranged from 3.2 to 44.6 Gy ( F =16.3,P ＜ 0.05 ).The Dmax and Dmean of the T1-2 stage patients were (40.8 ±9.4) Gy and ( 12.5 ±5.1 ) Gy,respectively,both significantly lower than those of the T3-4 stage patients [ (58.6± 14.8) Gy,(20.9± 9.3 ) Gy].The mean exposed volume of the T4 stage patients was significantly larger than that of the T1 and T2 stages patients.Conclusions In the IMRT of NPC,the HF receives rather high irradiation dose.T stage is the main factor influencing the dose,especially T3 and T4 stages deserve serious attention.

A comparision of three imaging modalities in image-guided radiotherapy / 中华放射医学与防护杂志

Objective To investigate and analyze the positioning accuracy of three imaging modalities utilized in image-guided radiotherapy (IGRT):electronic portal imaging device ( EPID),kV portal image (kV planar) and the kV cone beam computed tomography (CBCT).Methods 25 groups of setup errors were simulated on the phantom images through treatment planning system. Digitally reconstructed radiographs (DRRs) were constructed from the CT data which were subsequently used as references to register the EPID and kV planar images acquired at the original position.In addition,the reconstructed 3D-CT images were used to register the CBCT images.Finally,the setup errors using several registration methods were measured to investigate and compare the accuracies of the three imaging modalities used for patient setup.Results 675 groups of residual errors were analyzed.All combinations of imaging modalities and registration method were found to be accurate.The mean residual errors in three directions were less than 1 mm.The method based on grey value match of CBCT images was found as the most accurate with an uncertainty below 0.1 mm.When the manual match was used,the performance of kV planar was more accurate than that of EPID (residual error ＜ 0.65 mm).If automatic registration was applied,kV planar generated similar results as EPID did. Conclusions The three available imaging modalities and their corresponding registration methods are all competent for the clinical application of IGRT in our department.Considering the image quality,radiation dose and the accuracy of registration,CBCT has the priority on 1GRT followed by the kV planar.

The role of T1-weighted dynamic contrast-enhanced perfusion magnetic resonance imaging in gross target volume delineation of glioma patients / 中华放射肿瘤学杂志

ObjectiveTo investigate whether the T1-weighted dynamic contrast-enhanced perfusion magnetic resonance imaging (DCEPMRI) technique can help to delineate the clinical target volume of brain glioma patients.MethodsThe DCE T1-weighted images from 28 glioma patients were collected after GdDTPA was injected.After the acquired images were processed and analyzed using modified Tofts-Kermode'two compartment analysis model and de-convolution method,the value and its pseudo mapping of quantitative parameter Ktrans related to microvascular permeability were obtained.The tumor size in the largest diameter slice measured both in routine enhanced MRI and Ktrans mapping of T1-weighted DCEPMRI were compared.ResultsThe vascular permeability and tumor infiltration was lower in low grade glioma,the difference of the tumor size between T1-weighted DCEPMRI and routine enhanced MRI reached 0.2％ -0.3％ there was significant difference of tumor size between T1 -weighted DCEPMRI and routine enhanced MRI ( grade Ⅰ and Ⅱ grade with 2.93 cm2∶2.46 cm2(t=6.90,P=0.000) and 4.18 cm2∶3.21 cm2(t=10.22,P=0.000) ).While in high grade glioma,the vascular permeability and the tumor infiltration were higher,the difference of the tumor size between T1-weighted DCEPMRI and routine enhanced MRI reached 25％ - 26％( the size of grade Ⅲ and Ⅳ were 6.46 cm2 vs 5.48 cm2 ( t =10.83,P =0.000) and 8.26 cm2 vs 6.52 cm2(t =18.53,P =0.000) ).ConclusionsThe pseudo mapping of quantitative parameter Ktrans related to microvascular permeability acquired by T1-weighted DCEPMRI reflect the infiltrating circumscription in glioma,T1-weighted DCEPMRI can provide more information in delineation the clinical target volume,and it can be used as a new method for tumor volume evaluation.

Dosimetric verification of volumetric modulated arc therapy in nasopharyngeal carcinoma using COMPASS 3D patient anatomy based system / 中华放射医学与防护杂志

Objective To investigate the dosimetric performance of COMPASS system,a novel 3D quality assurance system for the verification of nasopharyngeal carcinoma volumetric modulated therapy (VMAT) treatment plan.Methods Eight VMAT treatment plans of nasopharyngeal carcinoma patients were performed with MasterPlan,a treatment planning system (TPS),and then these treatment plans were sent to the COMPASS and MOSAIQ system,a coherent control system,respectively.Comparison of the COMPASS reconstructed dose versus TPS dose was conducted by using the dose volume-based indices:dose received by 95％ volume of target ( D95％ ),mean dose ( Dmean ) and γ pass rate,dose to the 1％ of the spinal cord and brain stem volume ( D1％ ),mean dose of leaf and right parotid ( Dmean ),and the volume received 30 Gy for left and right parotid (V30).COMPASS can reconstruct dose with the real measured delivery fluence after detector commissioning.Results The average dose difference for the target volumes was within 1％,the difference for D95 was within 3％ for most treatment plans,and the γ pass rate was higher than 95％ for all target volumes.The average differences for the D1％ values of spinal cord and brain stem were ( 4.3 ± 3.0) ％ and ( 5.9± 2.9 ) ％ respectively,and the average differences for the Dmean values of spinal cord and brain stem were ( 5.3 ± 3.0 ) ％ and ( 8.0 ± 3.5 ) ％ respectively.In general the COMPASS measured doses were all smaller than the TPS calculated doses for these two organs.The average differences of the Dmean values of the left and right parotids were( 6.1± 3.1 ) ％ and ( 4.7 ± 4.4 ) ％ respectively,and the average differences of the V30 values of the left and right parotids were (9.4 ± 7.5 ) ％ and (9.4 ± 9.9)％ respectively.Conclusions An ideal tool for the VMAT verification,the patient anatomy based COMPASS 3D dose verification system can check the dose difference between the real delivery and TPS calculation directly for each individual organ,either target volumes or critical organs.