Objective To compare the dosimetry of three different radiation therapy plans [threedimensional conformal radiation therapy (3DCRT),intensity modulated radiation therapy (IMRT),intensity modulated arc radiotherapy (IMAT)].Methods Selected 15 cases with middle thoracic esophageal cancer,Varian Eclipse 8.6 planning systems were designed with 3DCRT,IMRT,IMAT,3DCRT using 5-8 coplanar radiation fields,IMRT using 7 coplanar radiation fields,IMAT using 2 radians.Three planned dose difference were compared.Results Compared with 3DCRT,IMRT and IMAT were better with heterogeneity index (HI),conformality index (CI),VPTV 95 ％,V5,V20,V35 of total lung,and V30 of heart (t =2.531,P＜ 0.05).There was no statistically significant difference for the V10,V15,V25,V30 mean dose of total lung,the mean dose of heart,the maximum dose of spinal cord,and the minimum dose of PTV among the three plans (t =1.325,P ＞0.05).Conclusion IMAT and IMRT are similar in the middle thoracic esophageal cancer radiotherapy target volume dose coverage and organs at risk protection,they are better than 3DCRT.IMAT in the monitor units and delivery time are less than IMRT.

Objective To evaluate the validity of narrow-band imaging (NBI) system in detection of colorectal adenoma, as compared to that of endoscopy of the colon and rectum, in a systematic review. Methods Relevant literatures were retrieved from Medline (January 1966 to October 2008), OVID (January 1996 to October 2008), EMBASE (January 1980 to October 2008), Coehrane Library (Issue 3, 2008) and Chinese Biological Medicine Disk (CBM disk, January 1997 to October 2008). Quality of the literatures retrieved was assessed based on the Cochrane Reviewers' Handbook and Jadad's score. RevMan version 4. 2 software was used for meta-analysis. Results Seven randomized clinical trials (2838 patients) were included in the study. Compared with white-light colonoscopy, no significant difference was observed in terms of adenoma detection rate (OR 1.18, 95% CI 1.00-1.39, P=0.06) by NBI system, which could significantly improve total number of detection for fiat lesions of the colon and rectum (pooled WMD 0.14, 95% CI 0.02-0.26, P=0.02), but with a longer withdrawn time (pooled WMD 1.05, 95% CI 0.08-1.22, P<0.01). Conclusions Detection rate for flat lesions of the colon and rectum, not for adenoma, can be improved by NBI system and meanwhile its withdrawn time is prolonged, indicating that routine use of NBI system for detecting colorectal adenomas may be recommended only with its further refined technique.

Objective Using Eclipse and Pinnacle3 V 7.4f treatment planning sytems (TPS) for dose calculation of the CT images of simulation phantom,patients and homogeneous organization phantom,to compare the differences between the two TPS for the calculation of non-uniform organizations.Methods For the CT images of simulation phantom,patients and homogeneous organization phantom,the calculating results between the two TPS were compared,including the common used clinical indexes of V20 and V30 of the lung,D95 of the planning target volume,the doses of the ISO and eight points of interest inside ISO slice.Resuits For simulation phantom and patients,although the calculating differences of the isocenter doses between the two TPS were small,the differences of other indicators were large.For example,when using secondary collimator irradiation,the maximal D95 difference of planning target volume reached 10.17%for patients and 4.64%for simulation phantom.When using muhileaf collimator irradiation,the maximal D95 difference reached 10.74%for patients and 5.66%for simulation phantom.Sometimes the dose differences of points 1-4 at the edge of planning target volume were more than 10%.In addition,the V30 differences of the lung were large too.But for the homogeneous organization phantom,the calculating differences were small.Conclusions The calculating differences between the two TPS are less for simulation phantom than for patients,and more for simulation phantom and patients than for homogeneous organization phantom.

ObjectiveTo study the efficacy of using multileaf collimators with different position and different degree in the treatment of nasopharyngeal carcinoma (NPC) using intensity-modulated radiotherapy techniques.Methods Ten patients withNPC were administered andanalyzed.Thepenumbra characteristics, dose of target, and radiation conformal indexes (CI) of mode T1 and mode T2 were measured and compared using dose volume histogram generated by Varian Eclipse three-dimensional planning computer system. Mode T1 :The angles of seven coplanar beams were 0°, 52°, 106°, 160°, 212°, 258°and 308°,respectively. There were no restriction on the position and degree of multileaf collimators. Parameters were set and optimized. Mode T2 :The beam angles and the parameters were as same as mode T1. According to the actual situations, the position and the degree of the multileaf collimators were changed. Then thedose optimization was performed. Results Target dose coverage in both mode T1 and T2 could be clinically accepted, and the CI were 0. 82 and 0. 83(t = -0. 25, P =0. 815). The maximum dose reductions in the lens, eyes, optic nerves and corneas were 28. 7% (t = 4. 80, P = 0. 000), 2. 7% (t = 2. 99, P = 0. 021),1.4%(t= 1.05,P=0.032), and 30.5% (t=2.99,P=0. 020), respectively. However, the mean dose and V35 of the parotid were increased by 0. 6% (t = - 2. 82, P = 0. 043) and 9.9% (t = - 2. 05, P =0. 038). ConclusionsOpimization of multileaf collimators can reduce the scattering and leaking rays. Compared with mode T1 ,controlling the position and degree of multileaf collimators could reduce the radiation dose to the eyes and optic-nerves, especially to the lens.

0.05).The variced recurrence rate in 1- and 2-year were 12% (3/25) and 20% (5/25) in TH glue group,and 39.1% (9/23) and 86.9%(20/23) in control group (P

Objecttve To compare the positional and volumetric differences of planning target volumes(PTVs)based on axial three-dimensional CT(3D-CT)and four-dimensional CT(4D-CT)for the primary tumor of non-small cell lung cancer(NSCLC).Methods Sixteen NSCLC patients with lesions located in the upper lobe and 12 patients with lesions in middle and lower lobes,totally 28 patients, initially underwent three-dimensional CT scans followed by 4D-CT scans of the thorax under normal free breathing.PTVvector was defined on gross tumor volume (GTV) contoured on 3D-CT and its motion vector. The clinical target volumes(CTVs)were created by adding 7 mm to GTVs,then, internal target volume (ITVs)were produced by enlarging CTVs isotropically based on the individually measured amount of motion in the 4D-CT,lastly,PTVs were created by adding 3 mm setup margin to ITVs. PTV4D was defined on the fusion of CTVs on all phases of the 4D data.The CTV wag generated by adding7 mm to the GTV on each phase.then,PIVs were produced by fusing CTVs on 10 phases and adding 3 mm setup margin.The position of the target center,the volume of target and the degree of inclusion(DI)were compared reciprocally between the PTVvector and the PTV 4D The difference of the position,volume and degree of inclusion of the targets between PTVvecter and PTV4D were compared,and the relevance between the relative characters of the targets and the three-dimensional vector was analyzed based on the groups of the patients. Results The median of the 3 D motion vector for the lesions in the upper lobe was 2.8 mm, significantly lower than that for the lesions in the middle and lower lobe ( 7.0 mm, z = - 3. 485, P < 0. 05 ). In the upper lobe group there was only significant spatial difference between the PTVvector and PTV4D targets in the center coordinate at the x axe (z = -2. 010, P < 0. 05 ), while in the middle and lower lobes there was only significant spatial difference between the PTVvector and PTV4D targets in the center coordinates at the z axe (z = -2. 136,P <0.05). The median of ratio of PTV4D and PTVvector, of the upper lobe group was 0. 75, significantly higher than that of the middle and lower lobes group (0. 52, z = - 2. 949, P < 0. 05 ).A significant correlation was found for the motion vector and the ratio of PTV and PTV4D in both groups ( r = - 0. 638, - 0. 850, P < 0. 05 ). For all patients, the median of D[ of PTV4D in PTVvector was 66. 39% ,while the median of DI of PTVvector, in PTV4D was 99. 55% , both showed a positive significant correlation with the motion vector (r = -0. 814,0. 613 ,P < 0. 05). Conclusions PTV4D defined based on 4D-CT simulation images is obviously less than PTV defined based on 3D-CT simulation images. The ratio and DI of both targets are related with the three-dimensional motion vector of the tumor.

Objective To compare positional and volumetric differences of internal gross tumor volume (IGTV) delineated separately by three approaches based on four-dimensional CT (4DCT) for the primary tumor of non-small cell lung cancer (NLCLC). Methods Twenty-one patients with NLCLC underwent big bore 4DCT simulation scan of the thorax. IGTVs of the primary tumor of NSCLC were tumor on the MIP images were delineated to produce IGTVMIP. The position of the target center, the volume of target, the degree of inclusion (DI) and the matching index (MI) were compared reciprocally between IGTV10, IGTVEI+EE and IGTVMIP. Results Average differences between the position of the center of IGTVs on direction of x,y and z axes were less than 1 mm, with no statistically significant difference. The volume of IGTV10 was larger than that of IGTVEI+EE, the difference was statistically significant (t=2.37,P=0.028);the volume of IGTV10 was larger than that of IGTVMIP, but the difference was not statistically significant(t=1.95 ,P=0.065). The ratio of IGTVEI+EE with IGTV10, IGTVMIP with IGTV10 were 0.85±0.08 and 0.92±0.11, respectively. DI of IGTVEI+EE in IGTV10, IGTVMIP in IGTV10 were 84.78% ± 8. 95% and 88.47% ±9.04%. MI between IGTV10 and IGTVEI+EE, IGTV10 and IGTVMIP were 0.85 ±0.09, 0.86±0. 09, respectively. Conclusions The center displacement of the IGTVs delineated separately by the three different techniques based on 4DCT images are not obvious; IGTVEI+EE and IGTVMIP can not replace IGTV10 , however , IGTVMIP is more close to IGTV10 comparing to IGTVEI+EE . The ratio of GTVEI+EE with IGTV10 is correlated to the tumor motion vector. As the vector increases, the ratio of GTVEI+EE with IGTV10decreases, especially for small tumors.

Objective To compare and analyze the dosimetric characteristics of the intensity-modulated arc therapy (RapidArc) combined with active breathing coordinator (ABC) in the thoracic esophageal carcinoma radiation therapy. Methods Ten thoracic esophageal carcinoma patients undergoing radiotherapy were selected for this study.The CT simulations were performed under three breath patterns respectively:moderate deep inspiration breath-hold (mDIBH) with ABC aid; Set the trigger threshold to 80％ of the peak of the respiration curve; and free breathing (FB).Based on the corresponding CT image sets,three treatment plans were generated for each patient respectively:Arc-ABC( three small arcs),ArcFB (consisted of two coplanar full arcs) and IMRT-FB plan.The following dosimetric parameters were compared among different plans:D2％,D98％,V95,homogeneity index ( HI),conformal index ( CI ) the percentage of volume receiving dose of over x Gy (Vx),monitor unit (MU),control points and treatment time.Results The planning target volume ( PTV ) of FB was 376 cm3 which decreased to 260 cm3 after using ABC.For mDIBH and FB patients,the total lung volumes were 5964.6 cm3(35％ more than FB) and 3838.8 cm3 respectively; the heart volumes were 524.4 cm3 and 642.7 cm3 respectively. No significant difference was observed among Arc-ABC,IMRT-FB and Arc-FB in terms of D2,D98,V95,CI and HI.For Arc-ABC plans,there were significant decreases of radiation dose in total-lung's V10,V20,V30,V40 and mean lung dose ( F =4.38,5.34,4.07,3.89,4.28,P ＜0.05).Various dose decreases of heart V20,V3,V40,Dmean and spinal cord Dmax were observed,yet no statistically significant difference existed.The MUs and total control points of Arc-ABC plans were significantly lower than other plans ( F =26.86,12.56,P ＜ 0.05 ).Conclusions When thoracic esophageal carcinoma patients were treated with radiotherapy,the combined utilization of RapidArc and ABC can potentially decrease the volume of irradiated lung yet escalate the dose in target.

ObjectiveTo explore the correlation between the respiration-induced clinical target volume (CTV) motion and volume variation and the dosimetric variation of planning target volume (PTV) and organs at risk (OAR) during free-breathing (FB) with whole breast intensity-modulated radiotherapy (IMRT).MethodsSeventeen patients with breast conserving surgery underwent respiration-synchronized four-dimentional computed tomography (4DCT) simulation scans on the state of FB.The treatment plan was constructed using the end-inspiration phase scan,then copied and applied to the other respiratory phases.The dose distribution was calculated separately to evaluate the dose-volume histograms parameters for the PTV,ipsilateral lung and heart.ResultsDuring FB,the CTV motion vector was (2.09 ±0.74) mm,and the volume variation was (3.05 ± 0.94) ％.There was no correlation between the volume variation of CTV and dosimetric variation of PTV/OAR ( r =-0.390 -0.480,P =0.182 -0.775 ).In anteroposterior (AP),superoinferior (SI) and vector directions,the CTV movement correlated well with the PTV mean dose,conformal index,and the lung volume receiving high dose (V20,V30,V40,and V50;r=-0.975-0.791,P =0.000 -0.041 ).In SI and vector directions,the CTV displacement only correlated with the heart volume receiving ＞ 5 Gy ( V5 ) ( r =-0.795,0.687,P =0.006,0.028 ).The lung volume variation and the lung volume receiving high dose correlated reasonably well (r=0.655 -0.882,P=0.001-0.04 0).The heart volume variation only correlated with the V5 of heart (r =-0.701,P =0.024).ConclusionsDuring free-breathing,the effect of breast volume variation can be ignored for whole breast IMRT,and whole breast IMRT assisted with breath-hold may improve the accuracy of dose delivery during radiotherapy.

Objective To explore the influence of delineator and contouring criteria training on the delineation of the tumor bed and whole breast target after breast-conserving surgery.Methods Twelve brcast cancer patients after breast conserving surgery were selected.Tumor bed marked by clips was defined as gross target volume 1 (GTV1),tumor bed formed by seroma was defined as GTV2 and the whole breast was defined as clinical target volume (CTV).Five junior radiation oncologists first delineated GTV1,GTV2 and CTV for each patient following their own criteria.After contouring criteria training,they then delineated GTV1,GTV2 and CTV for the same group of patients again.The differences of the volumes of GTV1,GTV2 and CTV before and after training among different delineators were compared.One-way ANOVA or matching t-test was performed.Results The inter-delineator variability on GTV1,GTV2 and CTV delineation before training was statistically significant (F =11.16,7.54 and 3.78,P =0.000,0.000 and 0.009).After training,the inter-delineator variability on GTV1 and GTV2 delineation had statistical significance (t =4.78 and 4.24,P =0.002 and 0.005),but the inter-delineator variability on CTV delineation had no statistical significance (t =1.52,P =0.209).The coefficient of variance of the GTV1,GTV2 and CTV before and after training was significantly different (t =3.14,2.81,2.70,P =0.009,0.017 and 0.021).The matching index of GTV1,GTV2 and CTV before and after training was significantly different (F =16.08,8.61,8.48,P =0.000,0.000 and 0.000).Conclusions In delineating the target of breast cancer,application of the criteria of target delineation can reduce the difference among the delineators,especially for CTV.