easurement should be performed in QA & QC program. Optimal image parameters should be chosen to reduce the scanning range and patient dose.

Objective To compare the dosimetric differences between helical tomotherapy (HT) and volume-modulated arc therapy (VMAT) in the treatment of upper thoracic esophageal carcinoma (UTEC).Methods A total of 10 patients with UTEC were randomly selected.HT plan and double-arc VMAT plan were designed and optimized for each patient.The prescription dose was 50 Gy/30 fractions for gross target volume (GTV), 66 Gy/30 fractions for planned target volume (PTV).The dose distribution and conformal index (CI), homogeneity index (HI) of target volume, the D1％, D5％, Dg5％, D99％, and dose of organ at risk (OAR) were analyzed by using the dose volume histogram (DVH).The monitor units and delivery time were also evaluated.Results For GTV and PTV, the D99％ of HT plans were slightly higher than those of VMAT plans (t =4.476, 3.756, P ＜ 0.05) , but no significant differences in D1％ , D5％ , D95％ , HI and CI (P ＞ 0.05) were found.The V10, V15, V20 and mean lung dose (MLD) to the total-lung of HT plans were all significantly lower than those of VMAT plans (t =-3.369,-4.824, -4.869,-3.657, P ＜ 0.05).There were no significant differences for V5, V30 and Dmax of cord (P ＞ 0.05).The monitor units and delivery time of VMAT plans were significantly lower than those of HT plans (t =13.970, 7.982, P ＜ 0.05).Conclusions Both HT and VMAT are appropriate for esophageal cancer radiotherapy.HT significantly reduces the radiation dose of the total-lung, while VMAT has obvious advantages in efficiency.

Objective To evaluate the variations of effective doges with the preset scanning parameters from linac-integrated kV cone beam CT( CBCT). Methods Weighted CT dose index(CTDIW) were measured with PTW TM30009 CT ion chamber in head phantom and body phantom, respectively, for different combinations of tube voltage, mAs, collimator and gantry rotation range. Dose length products(DLP) were derived from CTDIW and effective doses(E) were calculated by the DLP and EDLP. Results CTDIW and effective dose had the quadratical relationship with tube voltage, depending linearly on product of tube current and exposure time. Effective dose had close relationship with the collimator and the gantry rotation range. Both the DLP and ED for CBCT were lower than the reference dose level recommended for conventional CT. Conclusions Effective dose from CBCT has a close relationship with the scanning parameters. Optimal imaging parameters should be chosen according to the patient's anatomy to reduce patient dose.

Objective To evaluate the clinical feasibility of quality assurance of helical tomotherapy intensity modulated radiation therapy (IMRT) through a series of clinical case studies. Methods Tomotherapy planning system was used to provide optimized IMRT treatment plans. To verify the dose of IMRT plans,the cylindrical Virtual Water phantom,0.056cm3 AISL, ion chamber and EDR2 film were used for getting the absolute and relative doses from tomotherapy IMRT planning. The film and ion chamber were placed into the phantom. The doses of the interesting points and isodose distribution of the axial plane were measured,then the results were compared with those from the calculation in planning system for verification. Before the irradiation,kVCT images of the phantom were registered by tomotherapy MVCT images. So the setup of phantom was guided for verifying the position. Results The isedose distribution (on the axial plane) measured by the film was well consistent with that calculated by tomotherapy planning system. The error between the measured dose and predicted dose in the measured points was less than 3%. The setup error of the phantom was able to be kept within 1 mm. There was 2 mm offset along the vertical direction of couch from the virtual isocenter to beam isocenter,which should be considered during the phantom/patient setup. Conclusions The procedures for quality assurance of tomotherapy IMRT are feasible in our experience. And helical tomotherapy IMRT QA system has been constituted.

Objective To investigate the protective effect of the combined application of carlbachol and compound dietary fiber on the intestinal barrier function in burn rats.Methods The 30％ total body surface area (TBSA) Ⅲ scald Wistar rats were randomly divided into four groups.Rats in group A were fed with physiological saline,in group B were fed with compound dietary fiber,in group C were fed with carlbachol and in group D were fed with carlbachol and compound dietary fiber.The rats were sacrificed at 6,12 and 24 hours after treatment,and selected normal rats for control group.Blood samples were taken for detecting plasma endotoxin,D-lactic acid,D-lactic acid content.Tissue samples were harvested from the small intestine for pathological study under light microscopy.Results (1) The damage of the structure of small intestine mucosa was different among 4 groups,and the most obvious was at 24 h after treatment.(2)The level plasma of endotoxin in Group D was (0.517±0.034) EU/L,significant lower than that in group A ((0.659±0.074) EU/L),Group B ((0.589 ±0.027) EU/L) and Group C((0.587±0.026) EU/L),and the difference was significant(P＜0.05).(3) Dlactic acid level in Group D was (102.996±10.102) μg/L,significant lower than that in group A((133.538 ±8.621) μg/L),Group B ((121.223± 10.519) μg/L) and Group C ((122.700± 11.146) μg/L),and the difference was significant(P＜0.05).Conclusion In early stage of burn shock,the therapy of combined with carlbachol and compound dietary fiber has obvious protective effect on rat intestinal barrier.Meanwhile,it is better than the treatment effect of single carlbachol or compound dietary fiber to some extent.

Objective Mild hypothermia provides protection for the brain and improves prognosis in the treatment of severe traumatic brain injury, which is widely acknowledged.The article aimed to analysis the prognosis and complications of long-term and short-term mild hypothermia on patients with severe traumatic brain injury. Methods According to the cochrane systematic review methods, thorough search was carried out in databases including Cochrane, Pubmed, Embase, CBM, CNKI, Wanfang and VIP.Eval-uation was made on the quality of selected documents, and Revman5.2 software was applied for meta analysis after data extraction. Results Long-term mild hypothermia achieved improved prognosis compared to short-term mild hypothermia ( GOS score 4 ~5 ) [RR=1.37, 95%CI (1.14, 1.64), P=0.0006].No significant difference was found between these two therapies in pneumonia in-cidence (P=0.94), arrhythmia incidence ( P=0.54) and stress ulcer incidence (P=0.99). Conclusion In comparison to short-term hypothermia therapy, long-term mild hypothermia therapy improved the prognosis of patients with severe traumatic brain inju-ry without obvious increase in the incidence of pneumonia, arrhythmia and stress ulcer.

Objective To evaluate the dosimetric characteristics of helical tomotherapy (HT),intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiation therapy (3D-CRT) for postoperative radiotherapy of rectal cancer.Methods Ten male patients with stage Ⅱ or Ⅲ middle or low position rectal cancer were selected retrospectively.All of the 10 patients underwent Dixon surgery and CT simulation orientation.The target volumes and normal organs were drawn in the CT images and the plans for HT,IMRT and 3D-CRT were designed.The prescribed dose was given 50 Gy in 25 fractions,covering at least 95％ of the planning target volume.Results All plans met the needs of the prescribed doses.The HT and IMRT plans met the needs of dose limit to organs at risk,however,the 3D-CRT plans failed to do that.The conformity indexes of HT,IMRT and 3D-CRT plans were 0.86,0.82 and 0.62,respectively (F =206.81,P ＜ 0.001),and the homogeneity indexes were 0.001,0.157,and 0.205,respectively (x2 =15.8,P ＜ 0.001).The 3D-CRT plans had larger volumes than the HT plans and IMRT plans in the high-dose regions such as pelvic V50,bladder V40,bowel V50 and femoral head D5 (P ＜ 0.05),but the differences between the HT plans and IMRT plans were not statistically significant (P ＞0.05).The V15 value of bowel of HT plans were higher than those of the IMRT and 3D-CRT plans (71.1％ vs.63.3％ and 67.7％,respectively).However,there was no significantly difference.Conclusions All of the HT,IMRT and 3D-CRT plans are able to meet the prescription dose requirement of the target regions of rectal cancer.The HT plans show the best dose homogeneity and target conformity,followed by the IMRT plans,and then the 3D-CRT plans.The HT plans meet the needs of all OARs slightly better than the IMRT plans.3D-CRT plans are simple and practical with poor protective ability toward the OARs.

Objective To evaluate the curative effect and safety of mild hypothermia on patients with traumatic brain injury. Methods According to the cochrane systematic review methods , the data bases such as Cochrane, Pubmed, Embase, CBM, CNKI, Wanfang and VIP database were searched. The quality of included documents were assessed to extract meta analysis data. Results Compared to the control group, there was no statistically significant difference in patients treated by hypothermia for 3 days or less in mortality , but the difference was statistically significant after the summary [RR=0.74, 95%CI 0.64~0.85,P<0.000 1]; And there was no statistically significant difference in improving neural function of patients treated by hypothermia for < 3 days , but hypothermia improves the prognosis after the summary [RR=1.40,95%CI 1.24~1.59,P<0.000 01]. The difference was statistically significant in the incidence of pneumonia (P=0.007), there was no statistically significant difference in the incidence of arrhythmia (P=0.06), but the difference was statistically significant after sensitivity analysis. Conclusions Patients treated by hypothermia for < 3 days is not valid for clinical outcomes , the duration of the treament up to 3 days may not reduce mortality rates, but can improve the prognosis, lasts longer than 3 days or until the pressure back to normal, reducing the mortality rate, improve the neurological prognosis;but increased incidence of pneumonia, whether to increase the rate of cardiac arrhythmias have yet to be determined.

To investigate the dose effect of isocenter difference during IMRT dose verification with the 2D chamber array. The samples collected from 10 patients were respectively designed for IMRT plans, the isocenter of which was independently defined as P(o), P(x) and P(y). P(o) was fixed on the target center and the other points shifted 8cm from the target center in the orientation of x/y. The PTW729 was used for 2D dose verification in the 3 groups which beams of plans were set to 0 degrees. The γ-analysis passing rates for the whole plan and each beam were gotten using the different standards in the 3 groups, The results showed the mean passing rate of γ-analysis was highest in the P(o) group, and the mean passing rate of the whole plan was better than that of each beam. In addition, it became worse with the increase of dose leakage between the leaves in P(y) group. Therefore, the determination of isocenter has a visible effect for IMRT dose verification of the 2D chamber array, The isocenter of the planning design should be close to the geometric center of target.
Gamma Rays ; Humans ; Radiotherapy Dosage ; Radiotherapy, Intensity-Modulated ; instrumentation ; methods

OBJECTIVETo evaluate the radiation output and stability of linac-integrated kV cone beam CT unit.

METHODSAir kermas in radiographic mode were measured with 0.6 cc ion chamber and Unidos electrometer for Synergy-integrated XVI kV cone beam CT unit. Air kermas vs image frames were measured in fluoroscopic mode. Output stability and depth doses were measured.

RESULTSThe air kerma increased quadratically with the increased tube voltage, while increasing linearly with the tube current, exposure time, and number of frames. The radiation output stability and its change with the gantry angle were within +/-1%. The percentage depth dose increased with higher tube voltage.

CONCLUSIONThe radiation output of XVI is stable. The radiation outputs change considerably with the preset parameters. Parameters should be optimally chosen to reduce the patient dose.