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.

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.

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.

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.

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

Objective To explore the effect of respiration on dose accumulation for target volume and normal liver in radiotherapy for hepatocellular carcinoma (HCC) while applying 4D-CT and deformable registration.Methods Nineteen HCC patients who had received transcatheter arterial chemoembolization were enrolled in this study.All patients underwent 3D-and 4D-CT simulation in free breathing.The 3D dose (Dose-3D) was calculated from the treatment planning designed on the 3D-CT image.The Dose-3D then was recalculated on ten phases of 4D-CT images respectively,and the end-inspiration and end-expiration doses were defined as Dose El and Dose-EE.The 4D dose (Dose-4D) was obtained by deforming and accumulating ten-phase doses of 4D-CT images on the end-expiration phase image.The dosimetric differences of planning target volume and normal liver were compared among Dose-3D,Dose-4D,Dose-EI and Dose-EE.Results The D99 and D95of planning target volume (PTV) in Dose-3D were higher than those of Dose-4D,Dose-Fl and Dose EE (x2 =32.75,26.31,P ＜ 0.05).The conformal index (CI) and homogeneity index (HI) in Dose-3D were better than those of Dose-4D,Dose-E1 and Dose-EE,in which CI decreased from 0.78 to0.63,0.60 and 0.57,while HI increased from 0.08 to 0.15,0.16 and 0.19 (x2 =37.80,31.86,P ＜0.05).No statistically significant differences were found in dosimetric indices of PTV between Dose-4D and Dose EI,Dose-EE,and between Dose-El and Dose-EE (P ＞ 0.05).The mean dose (D),V5,V10,V20,V30 and V40 of normal liver were similar among four dose distributions (P ＞ 0.05).Conclusions More objective and precise dose distribution for target volume and normal liver could be obtained by applying both 4D-CT and deformable registration,which is beneficial to accurately predicting the dosevolume indices of radiation-induced liver injury and offering more reliable evidence of escalation for target dose.

Objective To study the feasibility of defining the internal gross tumor volume (IGTV) of hepatocellular carcinoma applying the enhanced four-dimensional computed tomography (4DCT) images with deformable registration technology.Methods Ten HCC patients who accepted radiation therapy were selected in this study.The 4DCT in free breathing,non-enhanced 3DCT and arterial phase enhanced 3DCT in end inspiration breath holding associated with active breathing coordinator were acquired sequentially.4DCT were sorted into ten series CT images according to breath phase,and named CT00,CT10..…CT90.Gross tumor volume (GTV) were contoured on different CT series and the IGTV1 was merged by ten phases GTVs of 4DCT.The GTV of enhanced 3DCT was registered to different CT series of 4DCT and the IGTVDR was obtained by merging the GTVs after deformable registration.The target volumes differences were compared by paired t-test.Results The edge of tumor was difficult to define on 4DCT and non-enhanced 3DCT images.The enhanced 3DCT image showed clearer tumor edge,and the GTV increased by mean 37.99％ compared to GTV on 4DCT different series images and non-enhanced 3DCT image (P =0.002).The GTV after deformable registration on 4DCT different phase images increased by mean 36.34％ (P =0.011),which were similar to GTV on enhanced 3DCT image (P =0.632).The IGTVDR increased by 19.91％ (P =0.017),compared to IGTV1.Conclusions The contrast-enhanced 4DCT image which was obtained by combining enhanced 3DCT and 4DCT images with deformable registration technology could raise the position precision of the HCC IGTV effectively.

Objective To investigate the variations of the spatial position and overlap ratio for gross tumor volume (respiratory phase 50％) (GTV50) and internal gross tumor volume (IGTV) of primary thoracic esophageal cancer during conventional fractionated radiotherapy based on repeated four-dimensional computed tomography (4DCT) scans.Methods Thirty-three patients with thoracic esophageal cancer underwent contrast-enhanced 4DCT scans before radiotherapy and at the 10th and 20th fractions of radiotherapy.Scans were registered to the baseline 4DCT scan using bony landmarks.The GTV50 was delineated by the same radiotherapist on each 4DCT imaging data set,and the IGTV was constructed accordingly.The target volume,degree of inclusion (DI),and matching index (MI) were compared in different phases.Results The volumes of GTV50 and IGTV decreased along with treatment course.No significant changes in the centroid position were observed for the GTV50 and IGTV.The median DIs of the target volumes at the 10th and 20th fractions in the original target volume were 0.75 and 0.63(P =0.000) for GTV50 and were 0.79 and 0.66(P=0.000) for IGTV,while the median MIs were 0.61 and 0.56(P=0.002) for GTV50 and were 0.68 and 0.58 (P =0.005) for IGTV.A positive correlation between the variation of volume ratio and the variation of DI was found for GTV50 and IGTV (r =0.632,r =0.783),and the variation of volume ratio was also positively correlated with the variation of MI (r =0.387,r =0.483) ;the 3D vector was negatively correlated with the MI (r =-0.455,r =-0.438).Conclusions During conventional fractionated radiotherapy,the variation of spatial position is less than 0.8 cm for GTV50 and IGTV of primary thoracic esophageal cancer,and the decline of the target leads to varying degrees of decreases in DI and the MI.

Objective To study the dosimetric impact of different angle fields in intensitymodulated radiotherapy (IMRT) and the feasibility of beam angle optimization (BAO) for multiple intracranial metastases.Methods In total,11 patients with multiple intracranial metastases were included in these analyses.Two treatment techniques were designed for each patient:the 7 equal spaced fields (BAF group) IMRT,and 7 fields by beam angle optimization (BAO group) IMRT.The dose distribution in the target,the dose to the organs at risk and normal brain tissues,and total MU in two groups were compared to explore the dosimetric differences.Results In comparison to the BAF group,the BAO group reduced the maximum dose to left and right lenses by an average of 45％,37％ (t =-5.707,-4.438,P ＜ 0.05);the mean dose to the left and right eyes were reduced by an average of 42.6％,44.5％ (t =-4.380,-5.638,P ＜0.05);the maximum dose to the right eyes were reduced by an average of 32.5％ (t =-2.518,P ＜ 0.05).The maximum dose of the right optic nerve and the mean dose of normal brain tissue were reduced by an average of 23％ and 3％ (t =-3.105,-3.437,P ＜0.05),respectively.For the target dose,conformity and homogeneity in PTV,no statistical differences were observed between the two groups (P ＞ 0.05).The BAO group reduced the maximum dose of the brainstem and the optic chiasm,as well as the number of MU,however,the differences were not statistically significant (P ＞ 0.05).Conclusions In comparison to the BAF group,the BAO group shows a similar target dose and reduces the dose for the organs at risk.For multiple intracranial metastases,IMRT protocols with BAO are feasible and beneficial.

Objective To investigate the variations of the spatial position and overlap ratio of the internal target volume (ITV) and planning target volume (PTV) of primary thoracic esophagus carcinoma using repeated four-dimensional computed tomography (4D-CT) scanning during conventional fractionated radiotherapy.Methods Thirty patients with thoracic esophageal carcinoma were included whose 4D-CT scans were conducted before radiotherapy and between every ten fractions.The gross tumor volumes (GTVs) were delineated by the same radiation oncologist on each 4D-CT image phase,and the ITV and PTV were constructed afterwards.Results No significant difference of the isocenters was observed for the ITV and PTV during the treatment course,yet both the volumes of the ITV and PTV decreased.The median DI (the degree of inclusion) of the target acquired subsequently in the original target were 0.85,0.77 (Z=-3.10,P ＜0.05) for ITV and 0.86、0.82(Z =-2.49,P ＜0.05)for PTV respectively during entire treatment.The variation of volume ratio correlated strongly with the variation of DI (the DI of the target acquired subsequent in the original target) (rITV =0.71,rPTV =0.77,P ＜0.05).The variation of volume ratio and the variation of the matching index (MI) were positively correlated (rITV =0.47,rPTV =0.59,P ＜ 0.05).The 3D vectors of ITV and PTV motions were negatively correlated with the corresponding MI (rITV =--0.52,rPTV =-0.36,P ＜ 0.05).If the initial PTV was used for treatment planning,8.80％ and 6.37％ of the target volume would be missed at the tenth and twentieth fraction (Z =-0.55,P ＞ 0.05),respectively.In the meanwhile,11.45％ and 18.49％ of the normal tissues would be wrongly irradiated at the corresponding time points (Z =-2.49,P ＜ 0.05).Conclusions The variations of the spatial position of all targets were all less than 0.6 cm.The DI and the MI of the target decrease by various degrees during the treatment course,which lead to target mispositioning and normal tissue irradiation at different levels.