Objective To analyze the 10-year survival outcome and failure patterns for patients with nasopharyngeal carcinoma (NPC) after intensity-modulated radiotherapy (IMRT),aiming to provide reference for optimized treatment for NPC. Methods Clinical data of 866 patients with NPC receiving IMRT from January 2001 to December 2008 were retrospectively analyzed. Survival analysis was performed using the Kaplan-Meier estimator. Univariate analysis was carried out by log-rank test and multivariate analysis was performed using Cox proportional hazards model. Results The median follow-up time was 132 months. The 10-year local recurrence-free survival (LRFS),distant metastasis-free survival (DMFS),progression-free survival (PFS) and disease specific survival (DSS) were 92.0%,83.4%,75.7% and 78.6%,respectively. A total of 210 patients died including 124 patients (59.0%) from distant metastasis,which was the primary cause of death,and 47(22.3%) from local regional recurrence. Independent negative factors of DSS included age>50 years (P=0.00),LDH≥245 IU/L (P=0.00),Hb<120 g/L (P=0.01),T2-T4 staging (P=0.00),N1-N3 staging (P=0.00) and GTV-nx>20 cm³(P=0.00).The 10-year LRFS,DMFS and DSS of stage Ⅱ NPC patients did not significantly differ after IMRT alone and chemoradiotherapy (P=0.83,0.22,0.23).For patients with stage Ⅲ NPC,the 10-year LRFS and DSS in the chemoradiotherapy arm were significantly higher than those in the IMRT alone (P=0.01,0.01),whereas no statistical significance was observed in the DMFS between two groups (P=0.14).The overall survival of stage Ⅳ a+Ⅳ b NPC patients is relatively poor. Conclusions IMRT can improve the long-term survival of NPC patients. Distant metastasis is the primary failure pattern. Patients with stage Ⅰ-Ⅱ NPC can obtain satisfactory survival outcomes after IMRT alone. The addition of chemotherapy can further enhance the LRFS and DSS of stage Ⅲ NPC patients. However,the optimal therapeutic strategy remains to be urgently investigated for stage Ⅳ a+Ⅳ b NPC patients.

Objective To evaluate the short-term efficacy and adverse events of pencil beam scanning proton and carbon ion therapy in the treatment of chordoma and chondrosarcoma of the head and neck. Methods Between July 2014 and July 31,2017,61 patients with chordoma and chondrosarcoma of the head and neck receiving proton and heavy ion therapy as the first course of radiotherapy were enrolled. Among them,45 patients were diagnosed with chordoma and 16 cases of chondrosarcoma,39 male and 22 female. The median age was 38 years old (range:14-70 years).The median maximum tumor diameter was 4.1 cm (range:0-8.6 cm).The clivus and the cervical spine were the primary tumor sites. Results Eight patients received proton therapy,21 patients were treated with proton combined with carbon ion therapy and 32 patients received carbon ion therapy. All patients successfully completed the planned radiotherapy. The medial follow-up time was 21 months (range:7-47 months).No grade 3-4 acute toxicity was observed. Only one patient suffered from radiation-induced temporal lobe injury. The 2-year progression-free survival (PFS) and overall survival (OS) were 91% and 100%. Conclusions Pencil beam scanning proton and heavy ion therapy yields relatively favorable short-term outcomes in the treatment of chordoma and chondrosarcoma of the head and neck. Nevertheless,the long-term clinical efficacy and safety remain to be investigated during follow-up.

Objective To evaluate the feasibility and clinical efficacy of preoperative simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) combined with neoadjuvant chemotherapy of capecitabine in patients with locally-advanced low rectal cancer. Methods Between 2015 and 2016,26 patients admitted to 301 Hospital who were diagnosed with locally-advanced low rectal cancer,which was located within 5 cm from the anal verge,were enrolled in this investigation. Dose fractionation pattern was delivered:58.75 Gy in 25 fractions (2.35 Gy/fraction) for rectal cancer and lymph node metastasis and 50 Gy in 25 fractions for the pelvic lymphatic drainage area and simultaneously combined with capecitabine chemotherapy (825 mg/m²,bid d1-5 weekly).One cycle of capecitabine (1250 mg/m²,twice daily,d1-14) was given at one week after the completion of chemoradiotherapy (CRT).Total mesorectal excision (TME) was performed at 6 to 8 weeks after the completion of CRT.The primary endpoints included pathological complete response rate (ypCR) and sphincter-preserving rate. The secondary endpoints included acute toxicity,tumor downstaging rate and postoperative complications. Results Twenty-six patients successfully completed neoadjuvant CRT,25 of them underwent surgical resection and one patient failed to receive surgery due to perianal edema. Postoperative ypCR rate was 32%(8/25),the sphincter-preserving rate was 60%(15/25),the tumor downstaging rate was 92%(23/25) and the R0 resection rate was 100%.During the period of CRT,grade 1 and 2 adverse events occurred in 24 patients,grade 3 radiation dermatitis was noted in 2 cases. No ≥ grade 4 acute adverse event was observed. Postoperative complications included ureteral injury in one case and intestinal obstruction in one patient. Conclusions Preoperative SIB-IMRT combined with neoadjuvant chemotherapy of capecitabine is a feasible and safe treatment for patients with locally-advanced low rectal cancer,which yields expected ypCR rate,R0 resection rate and sphincter-preserving rate. Nevertheless,the long-term clinical benefits remain to be elucidated.Clinical Trial Registry Chinese Clinical Trial Registry,registration number:ChiCTR-ONC-12002387.

Objective To evaluate the feasibility of total marrow and lymphatic irradiation (TMLI) with helical tomotherapy as a conditioning regimen before hematopoietic stem cell transplantation (HSCT). Methods Seven children with acute lymphoblastic leukemia and aplastic anemia were recruited as study subjects. The median age was 7 years old. The prescribed dose was 12 Gy/6 fractions twice daily. The exposure dose of the target and the organs at risk between helical helical tomotherapy-based TMLI regimen and total body irradiation (TBI) regimen were statistically compared,and acute toxicity grading was performed for all patients. Results Compared with the TBI regimen,the average exposure dose reduction for organs at risk after the TMLI regimen was ranged from 4.2% to 40.6%.The average exposure dose reduction for the kidney was the largest among all organs. The acute toxicities experienced by all patients were graded and recorded including 2 cases of nausea,5 cases of vomiting,1 case of anorexia,1 case of eryhema,3 cases of diarrhea,and 1 case of oral mucositis. Only grade 1-2 toxicities were observed,and no grade 3-4 toxicities occurred. Conclusions The findings in this study confirm the feasibility of helical helical tomotherapy-based TMLI regimen. Compared with the TBI regimen,the mean duration of treatment for the TMLI regimen with an equivalent dose is not increased. The exposure dose experienced by organs at risk is reduced and the predicted incidence rate is decreased when the TMLI regimen is employed,which provides a myeloablative pretreatment strategy. However,the long-term toxicity of TMLI regime remains to be evaluated by clinical trials.

Objective Because of statistical noise in Monte Carlo dose calculations,the effective point doses may not be accurately calculated. A user-defined sphere volume was adopted to substitute the effective point to take sphere sampling around the effective point,which minimize the random errors and improve the accuracy of statistical dose. Methods Direct dose measurements were performed at 0°and 90°using a 0.125 cm³ Semiflex ionization chamber (IC) 31010 isocentrically placed in the center of a homogeneous Cylindric sliced RW3 phantom (PTW,Germany).In the scanned CT phantom series,the sensitive volume length of the IC (6.5 mm) was delineated and the isocenter was defined as the simulated effective point. All beams were simulated in the treatment planning system (TPS) in accordance to the measured model. The grid spacing was calculated by 2 mm voxels and the relative standard deviation should be ≤0.5%.The statistical and measured doses were statistically compared among three IC models with different electron densities (ED;esophageal lumen ED=0.210 g/cm³ for model A,air ED=0.001 g/cm³ for model B and the default CT scanned ED for model C) at different sampling sphere radius (2.5,2.0,1.5 and 1.0 mm) to evaluate the effect of Monte Carlo.calculation uncertainty upon the dose accuracy. Results In the Monaco TPS,the statistical value was in the highest accordance with the measured value with an absolute average deviation of 0.49% when the IC was set as esophageal lumen ED=0.210 g/cm³ and the sampling sphere radius was 1.5 mm. When the IC was set as air ED=0.001 g/cm³ and default CT scanned ED,and,the recommended statistical sampling sphere radius was 2.5 mm,the absolute average deviations were 0.61% and 0.70%. Conclusion In the Monaco TPS,the calculation model with an ED of 0.210 g/cm³ and a sampling radius of 1.5 mm is recommended for the ionization chamber 31010 to substitute the effective point dose measurement to decrease the random stochastic errors of Monte Carlo.

Objective To evaluate the accuracy and reliability of the CyberKnife VSI system for stereotactic radiotherapy. Methods First,the mechanical accuracy of the robotic manipulator system,the repeatability of the Iris variable aperture collimator system,the couch position accuracy of the patient positioning system,the tacking precision of the target locating system and the dosimetric beam characteristics of the linac system for each subsystem of CyberKnife VSI system were tested. Finally,the total beam delivery precision of the CyberKnife VSI system was evaluated. Results The mean positioning deviations of the mechanical arm movement of the robotic manipulator system were less than 0.1 mm,and the maximum positioning deviation of single note was ≤ 0.29 mm. The repeatability of the aperture sizes for the Iris variable aperture collimator system was ≤ 0.28 mm. The couch position accuracy of the patient positioning system was<0.2 mm and the tracking precision of the target locating system was less than 0.5°. The linac beam-laser beam axes coincidence between the Iris and fixed collimators was better than 0.4 mm. The 6-MV beam parameters,such as beam quality and profile,were found within the acceptance limits. The deviations of output reproducibility,linearity and constancy versus linac orientation were less than 1.0%. The transmission factors of two types of collimators were lower than 0.4%. End-to-end test demonstrated that the maximum deviation of the total delivery precision of CyberKnife VSI system was 0.87 mm. Conclusion The CyberKnife VSI system is accurate and reliable for stereotactic radiotherapy.

Objective To evaluate the effect of helical tomotherapy (HT) megavoltage CT (MVCT) under different acquisition pitch and registration conditions upon the accuracy of radiotherapy for used nasopharyngeal carcinoma,aiming to provide reference for image-guided radiotherapy (IGRT) for nasopharyngeal carcinoma. Methods MVCT scans were performed on an anthropomorphic head& neck phantom which was simulated the positioning errors in the x,y and z direction. The obtained images were registered with the planning CT images. Acquisition pitch was set as the coarse,normal and fine modes. Registration conditions were set as bone registration,bone and soft tissue registration and full-image registration. Registration accuracy was determined by comparing the measured value with the preset value. The accuracy of radiotherapy under different acquisition pitch and registration conditions was statistically compared. Results The 3D errors of bone,bone and soft tissue and full-image registration under different acquisition pitch (coarse,normal and fine) were (1.51±0.47,1.54±0.35,1.81±0.53) mm and (1.41±0.37,1.53±0.36,1.56±0.39) mm and (1.51±0.27,1.57±0.32,1.73±0.33) mm,respectively. The bone registration yielded the highest accuracy (P<0.05).When the registration condition was set as bone registration,the accuracy of three acquisition pitch did not significantly differ (all P>0.05).The fine mode of acquisition pitch possessed the highest stability,whereas required the longest time. Conclusion The acquisition pitch and registration conditions should be selected during HT MVCT based on the clinical requirement of each patient with nasopharyngeal carcinoma.

Objective To analyze the relationship between planning factors of intensity-modulated radiation therapy (IMRT) and gamma index and investigate the effect of each parameter upon the γ passing rate of IMRT. Methods Gamma analysis was performed using 3%/3 mm acceptance criteria for 457 IMRT beams with different planning factors. During multi-factor ANOVA analysis of planning factors and gamma passing rate,the control variables primarily included the minimum segment area,minimum number of monitor unit (MU),number of segment,segment conversation,and the spatial resolution in the measured dose distribution. Results The percentage of pixels with passingγsignificantly differed under different minimum segment area,segment conversation and the spatial resolution in the measured dose distribution (all P<0.05).No significant correlation was observed between the passing rate and the minimum number of MU and the number of segment (P>0.05). Conclusions According to the actual situation of the equipment,the minimum segment area should be determined during IMRT planning. Direct machine parameter optimization should be performed. Appropriate resolution of the plane dose images can be chosen according to the minimum detector interval of dose matrix device.

Along with the intensification of the aging trend, the proportion of elderly patients suffering from esophageal cancer has been ever increased. Radiotherapy plays a pivotal role in the treatment of esophageal cancer in the elderly patients considering their relatively poor tolerance of surgery and high risk of postoperative complications. In this review, the development in the comprehensive treatment of esophageal cancer in the elderly was summarized.

For locally advanced rectal cancer,neoadjuvant chemoradiotherapy,followed by surgery and postoperative adjuvant chemotherapy has become a standard treatment mode. Neoadjuvant chemoradiotherapy can induce the tumors to shrink to different extent. Partial patients can obtain complete remission validated by postoperative pathological examination,which contributes to increasing the probability of radical surgery for rectal cancer patients,reducing the recurrence rate and improving the long-term clinical prognosis. In recent years,the prediction and evaluation of the clinical efficacy of neoadjuvant therapy has captivated widespread attentions from clinicians. In terms of imaging Methods,conventional morphological imaging techniques cannot accurately assess the clinical efficacy of neoadjuvant chemoradiotherapy,whereas DWI-MRI,DCE-MRI,PET-CT and other functional imaging techniques can not only reflect the degree of tumor shrinkage,but also reveal the changes in the functional metabolism of tumors before and after treatment and yield higher accuracy. In this article,recent application of imaging techniques in the evaluation of clinical efficacy of neoadjuvant chemoradiotherapy for rectal cancer was reviewed.

oncurrent chemoradiotherapy can improve the survival rate in patients with advanced pelvic tumors. However, it also increases the incidence of hematologic toxicity and other adverse events. Patients cannot tolerate these adverse events and discontinue the therapy. Pelvic bone marrow-sparing intensity-modulated radiotherapy (PBMS-IMRT) possesses obvious advantages in reducing the radiation dose and volume of the pelvic bone marrow. In this article, comparison between PBMS-IMRT and other irradiation therapies, correlation between dosimetric parameters and hematologic toxicity and imaging Methods with precise delineation of the active bone marrow were reviewed.