Objective:To discuss application of large aperture 16 row spiral CT in radiotherapy simulation positioning. Methods: To apply CT simulation positioning with large aperture 16 row spiral CT for the breast tangential field by early breast cancer after breast conserving surgery and radical radiotherapy. Compare CT-simulation and X-ray conventional positioning technique and Compare large aperture 16 row spiral CT and single row spiral CT image. Results: The application of large aperture 16 row spiral CT avoided the error because of body limited. Large aperture 16 row spiral CT simulation position validation error is superior to X-ray positioning. Its image quality is better than that of single row spiral CT. Conclusion:The application of large aperture 16 row spiral CT make simulation positioning more accurate, planned and treatment more accurate, it can provide guarantee of accurate simulation positioning for accurate plan and treatment.

Objective To analyze the influence of tumor volume change on intensity modulated radiotherapy(IMRT)for nasopharyngeal carcinoma by analyzing the repeated CT simulation.Methods Twenty nasopharyngeal carcinoma patients undergoing IMRT from July 2011 to November 2012 were selected in the study.The first CT simulation was conducted prior to radiotherapy,and the repeated CT simulation was finished after radiotherapy of 30 Gy.The first and the repeated CT images were fused in treatment planning system and GTV volume shrink rate was calculated.The original plan was used to recalculate the dose distribution on repeated CT.The dose volume histogram was used to calculate the dose difference of organs at risk including the brain stem and spinal cord.Results Compared with the first CT,GTV volume shrink rate of the repeated CT simulation was 28.7％,the maximum dose,1 cm3 volume and the average dose percentage of the brain stem and spinal cord were increased(t=0.83-3.17,P＜0.05).Conclusions GTV volume shrinked significantly after radiotherapy of 30 Gy in IMRT for nasopharyngeal carcinoma.The dose of the organs at risk increased accordingly.

Objective To compare the errors of final isocenter marking method and reference point marking method for CT simulation positioning in intensity-modulated radiotherapy (IMRT).Methods From 2009 to 2012,327 patients with head and neck cancer for IMRT underwent CT simulation positioning using the Philips Brilliance CT Big Bore scanner and Philips Tumor LOC workstation and were divided into final isocenter marking group (n =208) and reference point marking group (n =119) according to positioning methods.Target volume delineation and treatment plan design were performed on the Varian Eclipse treatment planning system (TPS).Before treatment,kilovoltage cone-beam CT scans and registration were performed with the Varian EX on-board imager system to obtain beam position errors in the right-left (RL),superior-inferior (SI),and anterior-posterior (AP) directions,and then comparisons of errors between the two groups were made by independent-samples t test.Finally,the TPS was used to measure the changes in the doses to the organs at risk after moving isocenters in the RL,SI,and AP directions among 5 patients with nasopharyngeal carcinoma.Results The mean beam position errors in the three directions were less in the final isocenter marking group than in the reference point marking group (P =0.02,0.01,0.03).After moving isocenters in the three directions,the target dose was reduced and the dose to the normal tissue around the target tumor was increased significantly.The error in the AP direction had the maximum influence on the spinal cord and brainstem.Conclusions Final isocenter marking method leads to less beam position error than reference point marking method in CT simulation positioning.Small isocenter motion can cause large changes in the doses to the organs at risk.

Objective To evaluate the effect of dose-rate and leaf position tolerance on the point dose in step-and-shoot intensity-modulated radiotherapy(IMRT). Methods IMRT plans of 2 prostate cancer patients were selected and recalculated for a water phantom.An ionization chamber was used to measure the dose of some points in the phantom at five nominal dose-rates:100 MU/min,200 MU/min,300 MU/min,400 MU/min and 500 MU/min.It was necessary to adiust the position of the water phantom to locate the ionization chamber in region where the dose gradient was very low in order to minimize the effect of dose gradient on the measured results.When measuring the effect of leaf position tolerance on point dose,the dose-rate was kept constant and the values of tolerance were 1 mm,2 mm,3 mm and 4 mm.This work was conducted on a Varian 23EX equipped with a Millennium 120-leaf multi-leat collimator(MLC).The treatment planning system was Varian Eclipse. Results As the dose-rate increased,the error between the measured dose and the calculated dose also enlarged.The difference between the maximum and the minimum was 1.2%.When MLC control system was working normally,tlle effect of leaf position tolerance on the measured point dose was very little and negligible. Conclusions The dose-rate must be selected suitably to ensure that the delivery can be finished in a short time with the radiobiological effect taking into account.It should be noted that the error between the measured dose and the calculated dose increases with the trend of inereasing more rapidly at higher dose rates.The value of leaf position tolerance should not be set too large,in order to minimize the difference between the measured dose and the planned dose in the region of steep gradient and find as early as possible when the multi-leaf collimator control system performs improperly.

Acquired Immunodeficiency Syndrome ; immunology ; HIV Infections ; immunology ; Humans ; Medicine, Chinese Traditional ; T-Lymphocytes ; physiology

Animals ; Cyanides ; toxicity ; Mice ; Random Allocation ; Toxicity Tests, Chronic

Objective To investigate the relationship of placental vascular anastomosis and physical development and morbidity of the disease in twin neonates.Methods Fourteen pairs of twin neonates deliveried from Sep.2005 to Aug.2009 were enrolled in Newborn Intensive Care Unit,the Third Affiliated Hospital of Zhengzhou University.These twins were divided into 2 groups according the conditions of placental vascular anastomosis:significant placental vascular anastomosis group(group A) and no significant vascula anastomosis group(group B).Birth weight,head circumference,length,the morbidity of disease were all investigated in 2 groups.Clinic follow-up included neonatal behavioral neurological assessment(NBNA) and children′s development center of China(CDCC).The correlation of neonates placental vascular anastomosis between twin neonates were compared.Results There were statistically significant differences between group A and group B in birth weight,head circumference and body length(t=6.070,5.237,5.784,Pa

Objective To evaluate the short-term therapeutic effect and radiation reaction of stereotactic radiotherapy for early stage non-small cell lung cancer in the elderly patients. Methods Thirty-one patients with stage Ⅰ - Ⅱ non-small cell lung cancer were treated with stereotactic radiotherapy. Patients aged 70-88 years, median age 76; 21 were stage I patients, and 10 stage Ⅱ ; 14 patients had tumor

Objective To evaluate the efficacy and tolerance of preoperative concurrent chemoradiotherapy in the treatment of locally advanced middle-low rectal cancer.Methods From June 2007 to June 2013,51 untreated patients with histopathologically proven rectal cancer (T3/T4 or N (+))were included in this study.Three-dimensional radiotherapy was delivered to the whole pelvic cavity at 45.0-50.4 Gy/25-28 fractions.Two cycles of chemotherapy with FOLFOX4 or XELOX were given concurrently at weeks 1 and 4 of radiotherapy.Surgery was performed at 4-8 weeks after chemoradiotherapy.Adjuvant chemotherapy with FOLFOX4 or XELOX was given within one month after surgery.The Kaplan-Meier method was used to calculate survival rates,and the log-rank test was used for univariate analysis;the Cox regression model was used for multivariate prognostic analysis.Results Fortynine patients completed the preoperative chemoradiotherapy and surgery.The median follow-up was 2.9 years.The overall sphincter preservation rate was 65％;the overall downstaging rate was 59％.Ten (20.4％) of all patients achieved a pathologic complete response (pCR).Grade ≥3 toxicities occurred in 25％ of all patients,and the overall postoperative complication rate was 31％.The 3-and 5-year sample sizes were 24,12,respectively.The 3-and 5-year overall survival rates were 81％ and 69％,respectively;the 3-and 5-year disease-free survival (DFS) rates were 76％ and 60％,respectively;the 3-and 5-year local recurrence-free survival (LRFS) rates were 78％ and 70％,respectively;the distant metastasis-free survival rates were 82％ and 74％,respectively.The multivariate analysis showed that tumor downstaging was an independent prognostic factor for 5-year DFS and LRFS.Conclusions For locally advanced middle-low rectal cancer,preoperative radiotherapy with concurrent FOLFOX4/XELOX chemotherapy can increase pathologic downstaging rate,pCR rate,and sphincter preservation rate.Patients with tumor downstaging may have a better survival advantage.

Objective To explore a method of using a computer system for multi-media cases study in radiation oncology clinical work,in order to replace the traditional use of film images and paper.Methods We use a dedicated networked computer's Windows XP's Remote Desktop feature to remote access an Eclipse TPS and the radiation therapy information management system.Then we can online read the patient' s information of CT images,target volumes,treatment plans,plan application forms and electronic medical records,and use a projector to project it on the screen.Results There has been half a year since we successfully set up a radiation therapy case study multi-media system in the department.It's convenient and effective to achieve the department conducted a collective case discussion.Conclusions The equipment required is simple,and it's a safe and reliable technology,greatly improving the clinical efficiency and quality of medical care.