More and more attention tend to the application of intensity modulated radiation therapy (IMRT) treatment of malignant cancer.The accuracy of the radiotherapy is raising because of the increased radiosensitivity of bone marrow.Imaging modality quantified the distributions of bone marrow.,which could further reduce the volume to avoid.Bone marrow-sparing intensity-modulated radiotherapy can reduce the pelvic bone marrow irradiation volume,which may reduce the probability of acute bone marrow inhibit.It is worthy of application widely.

ObjectiveTo quantitative analysis the difference of organ contour using planning CT and kilovolt cone beam CT (KVCBCT) deformable registration.MethodsOne set planning CT image and ten sets of KVCBCT image of one patient were choose and total five patients.Organ contour were automatic outlined to using deformable registration.To compare the organ contours different of deformable registration (DR) and rigid registration (RR).Statistic analysis was executed with paired t-test for dice similarity coefficient (DSC) value and sensitiveness (SENS) value.ResultsThe DSC value of body,left,right lung,heart and spinal respectively:0.971 and 0.980 ( t =3.89,P =0.000 ),0.836 and 0.873 ( t =4.41,P =0.000),0.873 and 0.888 ( t =3.88,P =0.000 ),0.738 and 0.764 ( t =4.83,P =0.000 ),0.666 and 0.677 ( t =2.04,P =0.047 ).The SENS value:0.975 and 0.981 ( t =1.41,P =0.003 ),0.914 and 0.803(t=-6.88,P=0.000),0.926 and 0.800(t=-7.06,P=0.045),0.782 and 0.708(t=-2.50,P=0.040),0.625 and 0.796 (t =-9.09,P =0.000).ConclusionsRR is at a competitive disadvantage in terms of organ contour outline.The body,left and right lung that are used DR have advantage over the heart and spinal.

Objective To compare the displacements of the clips in the cavity measured with orthagonal kilovoltage (KV) X-my plain film in conditions of moderate deep inspiration breathing hold(mDIBH) and free breath (FB), and compare the margins from clinical target volume (CTV) to planning target volume (PTV) based on the displacements. Methods Before radiotherapy, 2 and 5 sets of orthogonal KV plain film were respectively collected in mDIBH and FB group, then the automatic registration of the reconstructed KV plain film and DRR derived from the planning OF images was finished. In conditions of mDIBH and FB, the displacements of the selected clip at the same location in the different directions and of the different selected clips in the same direction were compared. The margins in three dimensional directions were calculated and compared in conditions of mDIBH and FB . Results In FB hold group, the difference of displacement in left-right (LR), cranial-caudal (CC) and anterior-posterior (AP) directions were statistically significant between the clips at the cranial and caudal border of the cavity (9. 7 mm and 10. 6 nun (Z = -2. 12,P =0. 037) ,7. 3 mm and 8. 3 mm (Z = -2. 31 ,P=0. 041) ,15.5 mm and 16. 1 nun (Z = -2. 32,P = 0. 041)), but not statistically significant for the clips at the bottom and lateral P=0.814),15.7 mm and 16.5 mm (Z=-0.26,P=0.856)). The corresponding differences in the different directions were statistically significant (5.0 mm and 7. 8 mm(Z = -2. 31, P =0. 036), 5.0 mm and 9. 3 nun (Z= -2. 21,P=0. 021),7. 8 mm and9.3 mm (Z= -2. 11,P=0.041)). In FB group, the differences of the displacements of the four selected clips were statistically significant in CC and AP directions (7.3 mm and 8.4 mm (Z= -2.45,P=0.021), 15.5 mm and 16.5 mm (Z= -2.41,P= 0.043)), but not in LF direction (10.6 nun and 10.6 mm (Z= -0.24,P=0. 815)). In mDIBH group, the displacements in LF direction were statistically significant (4. 4 mm and 5.4 mm (Z = -2. 31, P = O. 031)), but not in CC and AP directions (8. 6 mm and 8.6 mm (Z =-0. 21, P = 0. 815), 10. 5 mm and 10. 8 mm (Z = -0. 27 ,P =0. 754)). There were statistically significant difference of the margins in LF and AP directions (9.7 mm and 5.0 mm (Z= -2.34,P=0.029),15.5 mm and 9.3 mm (Z= -2. 31,P= 0.021)), but not in CC direction (7.3 mm and 7. 8 mm (Z= -0.29,P =0.770)) between mDIBH and FB conditions. Conclusions The margins extended from CTV to PTV for EBPBI should be determined based on the respiratory status, border location and border direction.

Objective To research the feasibility of using three-dimensional CT (3DCT) associated with active breathing control (ABC) in determination of the individual internal tumor volume (ITV) for hepatocellular carcinoma (HCC) comparing the four-dimensional CT (4DCT).Methods After 4DCT scans of 15 HCC patients who had accepted TACE,completed the 3DCT scans associated with ABC in three ways of breathing:free breathing ( FB),end inspiration hold ( EIH),end expiration hold (EEH).4DCT images were sorted into 10 phases and the maximum intensity projection (MIP) images were constructed.The GTVs were manually contoured on 4DCT and 3DCT images (labeled as GTV0,GTV10.….GTV90,GTVMIP,,GTVFB,GTVEIH and GTVEEH).GTV0…GTV90,GTV0 and GTV50,GTV0,GTV20 and GTV50,GTVEIH and GTVEEH were respectively merged into IGTV1,IGTV2,IGTV3,IGTV4.The volume and geometry displacement of GTVs and IGTVs were compared.Results All patients were compatible with the ABC technique and completed the CT scans in two ways.The motion of diaphragm measured between 4DCT and 3DCT images was not significantly different ( 1.39 cm and 1.39 cm,t =-0.02,P =0.983 ),it was similar to the volume difference among GTV0,GTV20,GTV50,GTVEIH,GTVEEH and GTVFB (56.4,54.6,55.5,55.6,55.2,59.7 cm3,F =0.01,P =1.000 ).The comparison result of volume difference among IGTV1,IGTV2,IGTV3,IGTV4 and GTVMIP (77.9,71.4,73.4,72.3 and 66.3 cm3,F =0.02,P =1.000)were similar to the differences of geometry displacement in x,y and z axial among them (F =0.48,0.04,0.02,P =0.750,0.997,0.999,respectively).Conclusion The application of 3DCT associated with ABC in determination of the individual IGTV for HCC is feasible and safe comparing to 4DCT.

Objective:To evaluate the feasibility of delineating subvolume target in radiotherapy for brain tumors using Gd-based contrast clearance difference.Methods:Twenty-six patients with malignant brain tumors were scanned with MRI. The first and second acquisitions of standard T 2-weighted images (T 2WI) and T 1-weighted images (T 1WI) were performed at 5 min and 60 min after injection of contrast agent. Delayed contrast extravasation (DCEM) MRI computed by Brainlab comprised regions of contrast agent clearance representing active tumors and regions of contrast accumulation representing non-tumor tissues. Based on T 2WI images, 14 patients with liquefaction necrosis were divided into group A, and 12 patients without liquefaction necrosis into group B, respectively. Then, gross target volume (GTV) was delineated on T 1WI images. Based on the GTV, active tumor (GTV tumor) and non-tumor regions (GTV non-tumor) were delineated on T 1WI-DCEM fusion images, while liquefaction necrosis (GTV liquefaction) and non-liquefaction (GTV non-liquefaction) were delineated on T 1-T 2WI fusion images. Finally, the differences between different subvolumes were compared by paired t-test. Results:In group A, the GTV non-liquefaction and GTV liquefaction were (13.65±18.15) cm 3 and (6.30±7.57) cm 3. The GTV tumor was (10.40±13.52) cm 3 and the GTV non-tumor was (9.55±14.57) cm 3. The GTV non-liquefaction was significantly increased by 16.3% on average compared with the GTV tumor ( P<0.05). The GTV non-tumor was significantly increased by 16.3% on average compared with the GTV liquefaction ( P<0.05). In group B, The GTV non-tumor was significantly reduced by 68.8% on average compared with the GTV tumor ( P<0.05). Conclusions:Compared with T 2WI, DCEM has advantages in identifying the liquefaction area and can clearly differentiate the subvolume of active tumors from non-liquefaction necrosis. DCEM provides evidence for guiding the delineation of subvolume in primary and metastatic brain tumors.

Objective:To evaluate the effect of different reconstruction images on cardiac dose evaluation by comparing the differences between 4D-CT series and special reconstruction images in evaluating the dose-volume index of cardiac structures.Methods:ECG 4D-CT series were scanned in 15 female patients with left breast cancer. The images of 0-95% 20 phases were reconstructed at an interval of 5% cardiac cycle. The maximum intensity projection (MIP), minimum intensity projection (MinIP), average intensity projection (AIP) and sum intensity projection (SIP) images were obtained by special reconstruction of 4D-CT series. Left ventricle (LV) and left anterior descending coronary artery (LADCA) were delineated on 4D-CT and special reconstruction series, respectively. The intensity-modulated radiation therapy plan of the left breast cancer was designed on the basis of 0% phase, and the cumulative dose (Dose-cumulate) of 20 phases was obtained by deformation registration. The doses of 0% phase were deformed and registered to MIP, MinIP, AIP and SIP images to obtain the corresponding dose distribution. The dose-volume indexes of LV and LADCA based on different CT images were compared.Results:In the evaluation of dose-volume index of LV, compared with 4D-CT series, the change rates of V 5Gy, V 30Gy, V 40Gy, D max and D mean on MIP images were 3.8%, 2.0%, 0.9%, 3.8% and 1.7%, respectively. There was significant difference in V 5 and D max between MIP and 4D-CT (both P<0.05). Compared with 4D-CT, the change rates of D max on MinIP, SIP and AIP images were 2.5%, 3.1% and 1.5%, respectively (all P<0.05). In the evaluation of dose-volume index of LADCA, only the change rate of D max on four special reconstructed images was<5%( P<0.05). Conclusions:In the dose-volume evaluation of LV, the V 30Gy, V 40Gy and D mean obtained by MIP are basically equivalent to those obtained by 4D-CT series, which can be used to substitute 4D-CT series to evaluate the dose-volume. The special reconstruction image of LADCA can not replace 4D-CT series.

Objective To study the feasibility of helical tomoterapy (HT) at prescription dose escalation for nasopharyngeal carcinoma (NPC).Methods Static-IMRT (sIMRT) and HT plans were designed for 10 nasopharyngeal carcinoma patients which were treated by sIMRT and HT treatment plan.Prescription dose was escalated for each plan until any organs at risk (OARs) reached the quantitative analysis of normal tissue effects within the clinical threshold.Dosimetric factors of target and OARs were analyzed for both sIMRT and HT plans.Results Compared with sIMRT plan, prescribed dose of HT plans increased 42.6％ (t =6.373, P ＜ 0.01), and the homogeneity index was also improved (t =-2.288, P＜0.05);the conformity index decreased (P ＞ 0.05).The limits of HT prescribed dose escalation were spinal cord (2 cases), optic nerve (5 cases) and brainstem (3 cases).The limits of sIMRT prescribed dose escalation were lens (1 case), spinal cord (1 case) and parotid (8 cases).Conclusions HT could improve prescription dose of nasopharyngeal carcinoma while keeping the OARs safe.Compared with sIMRT, HT technology might be used at high dose NPC radiotherapy.

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 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 morphology of normal liver and tumors by breathing motion of hepatocellular carcinoma patients,through comparing the modified demons algorithm and FFD algorithm based on B-spline,and combing four-dimensional computed tomography (4DCT).Methods The 4DCT images of 8 HCC patients were segmented into 10-series which were named CT0,CT10 … CT80,CT90 according to the respiratory phases,CT0 and CT50 are defined to be end-inhale and end-exhale respectively.CT50 was chosen as the reference image.We used the modified demons algorithm and FFD algorithm based on B-spline to deform the images.Linear interpolation was used in both mode 1 and mode 2.The normalized mutual information (NMI),Hausdorff distance (dH) and registration speed were used to verify the registration performance.Results The average NMI for the end-inhale and end-exhale images of 8 HCC patients after demons registration in mode 1 improved 4.75％ with FFD algorithm based on B-spline(P =0.002).And the difference of dH after demons reduced 15.2％ comparing with FFD model algorithm (P =0.02).In addition,demons algorithm has the absolute advantage in registration speed(P =0.036).Conclusions The breathing movement for deformation of normal liver and tumor targets is significant.These two algorithms can achieve the registration of 4DCT images and the modified demons registration can deform 4DCT images effectively.