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Objective To analyze the dosimetric and delivery efficiency differences between IMRT plans based on Halcyon and Trilogy Accelerator for left side breast cancer.Methods A total of 10 patients with left side breast cancer based on the Trilogy platform were retrospectively analyzed.For each patient,plan based on Halcyon was redesigned using Eclipse Version 15.1 TPS.In order to evaluate plan quality,dose coverage of target and dose to organs at risk,monitor unit efficiency,segment size and delivery time were compared.Results Halcyon treatment platform could meet the clinical objective.Dose distribution of the target volume had no significant difference with the Trilogy plans (P＞0.05).Volumes receiving 10 Gy,20 Gy and D of the left lung were significantly reduced(Z=-2.22--1.78,P＜0.05).V5 of heart for Halcyon and Trilogy was(27.80±7.66)％ and (23.18±8.19)％,respectively(Z=-0.71,P＜0.05),while D was (7.03± 1.8)Gy and(7.11±2.40)Gy,respectively(P＞0.05).Halcyon increased the monitor unit from 1 526.2±227.7 by Trilogy to 1 770.5±383.9(Z=-0.71,P＜0.05),but decreased the delivery time from (12.38± 1.49) min by Trilogy to (3.01 ±0.28) min (Z =-3.42,P＜ 0.05).Conclusion Halcyon treatment platform can meet the clinical requirements,reduce dose to normal tissue with high delivery efficiency.
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Objective To evaluate the dynamic variation of the dose-volume parameters of the left ventricular myocardium following heart beat in radiotherapy for esophageal cancer. Methods The left ventricular myocardium of 22 patients was contoured on 20 phases (0％-95％) of electrocardiography (ECG) gated heart 4DCT images. The radiotherapy plan was designed on the simulation CT images,and then the dose distribution of radiotherapy plan was imported into MIM Maestro system and 4D dose-volume histogram (DVH) was reconstructed. The variations of position,volume and dice similarity coefficient (DSC) of the left ventricular myocardium were analyzed. The changing ranges of Dmean ,V10,V20 ,V30 and V40 of the left ventricular myocardium during different phases were statistically compared. Results ( 1 ) The biggest displacement of the left ventricular myocardium was in Y axes. The maximum variation rate of volume and DSC of the left ventricular myocardium were (24.23±11. 35)％ and (184.33±128. 61)％ in different phases with statistical significance (both P<0. 05).(2) The maximum variation rate of Dmean of the left ventricular myocardium was (87.05± 38. 34)％ in different phases with the highest rate of 163. 52％ with statistical significance (P<0. 05).(3) The maximum variation values of V10,V20,V30 and V40 of the left ventricular myocardium were (13.64±4. 33)％,(12.84±4. 55)％,(11.62±4. 85)％ and (3.63±2. 56)％ with statistical significance (all P<0. 05). Conclusions The impact of heart beat on the dose-volume parameters of the left ventricular myocardium should be considered during esophageal cancer radiotherapy. Traditional static 3DCT-based assessment of the dose-volume parameters of the left ventricular myocardium can yield relatively large errors, which is probably reduces the prediction efficiency of the dose-volume parameters for radiation-induced heart injury.
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Objective@#To investigate the potential dosimetric benefits of four-dimensional computed tomography (4DCT) compared to three-dimensional CT (3DCT) in the planning of radiotherapy for external-beam partial breast irradiation (EB-PBI).@*Methods@#Three-DCT and 4DCT scan sets were acquired for 20 patients who underwent EB-PBI. For each patient a conventional 3D conformal plan (3D-CRT) was generated based on end-inhalation phase (EI). The treatment plan based on the 4DCT EI phase images was copied and applied to the end-exhalation phase (EE) and 3DCT images (defined as EB-PBIEI, EB-PBIEE, EB-PBI3D, respectively).@*Results@#The median volumes of the tumour bed based on 3DCT, EI and EE were 20.99 cm3, 19.28 cm3, and 18.78 cm3, respectively. The tumour bed volume based on 3DCT was significantly greater than that of EI and EE volumes (P<0.05). The planning target volumes (PTV) coverage of EB-PBI3D, EB-PBIEI and EB-PBIEE were 96.85%, 97.51%, 97.03%, respectively. The planning target volume (PTV) coverage of EB-PBI3D was significantly less than that of EB-PBIEI and EB-PBIEE (P<0.05). The median homogeneity indexs (HI) based on 3DCT, EI and EE were 0.13, 0.13, 0.13, respectively. The median conformal indexs (CI) based on 3DCT, EI and EE were 0.68, 0.69, 0.68, respectively. The median mean doses (Dmean) based on 3DCT, EI and EE were 36.20 Gy, 36.20 Gy, 36.22 Gy, respectively. However there were no significant differences in the homogeneity index, conformity index and the mean dose of PTV between the three treatment plans (P>0.05). The EB-PBI3D plan resulted in the largest organs at risk dose (P<0.05).@*Conclusion@#There was a significant benefit when using 4DCT to plan 3D-CRT for EB-PBI with regard to reduced non-target organ exposure, and might result in poor dose coverage when the PTV is determined using 3DCT.
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Objective To evaluate the position deviation of multi-leaf collimator (MLC) in volumetric modulated arc therapy for nasopharyngeal carcinoma and to verify a method of detecting the leaf position accuracy.Methods Thirty-two volumetric modulated arc plans of nasopharyngeal carcinoma were randomly selected.A clockwise arc with a gantry range of 181° to 179° and a counterclockwise arc with a gantry range of 179° to 181° were uscd for each plan.Each arc contained two leaf groups,groups A and B.By using the Argus software,the actual MLC leaf positions were extracted from the Dynalog files in the Varian Trilogy accelerator.The planed MLC leaf positions were compared with the actual positions,and the differences were calculated between them.Results The proportions of the leaf position errors within ± 2,± 1.5,± 1 and ± 0.5 mm were 99.99％,99.90％,99.07％ and 93.98％,respectively.The proportions of the leaf position errors within ± 1 mm were 98.08％,100％,98.97％ and 99.01％ for the first therapeutic arc (ARC1),second therapeutic arc (ARC2),A and B groups,respectively.The leaf position errors range of ARC1 and ARC2 were-2.95 to 2.99 and-0.22 to 0.23 mm (t =2.35,P ＜ 0.01).The leaf position errors range of leaf bank A and leaf bank B were-2.95 to 2.68 and-2.92 to 2.99 mm(P ＞ 0.05).Conclusions During the volumetric modulated arc radiotherapy,the leaf positions deviation are in control.The Dynalog files can be used as an effective way to analysis the leafposition errors.
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Objective To evaluate the dosimetric effects of target volume delineation with metal clip and seroma,alone or in combination,on external-beam partial breast irradiation (EB-PBI) based on four-dimensional computed tomography (4DCT).Methods Twenty female patients undergoing EB-PBI from 2009 to 2013 were enrolled as subjects.The gross tumor volumes (GTVs),GTVC,GTVS,and GTVC+S,were delineated on 4DCT images at 10 phases using metal clip,seroma,and both of them,respectively.The GTVS on 4DCT images at 10 phases were fused to generate the internal gross tumor volumes (IGTVS),IGTVC,IGTVS,and IGTVC+S.The planning target volumes (PTVS),PTVC,PTVS,and PTVC+S,were obtained via expansion of margin by 15 mm.The three-dimensional conformal radiotherapy plans were made by one physician based on PTVC,PTVS,and PTVC+S on end-inhalation images.The target volume,homogeneity index (HI),conformity index (CI),and doses to organs at risk were compared between the three groups.Results The C+S group had the largest IGTV,PTV,and the ratio of PTV to diseased breast volume,which was followed by the C group and the S group (all P＜ 0.05).The S group had significantly lower doses to the ipsilateral normal breast and lung than the C group and the C+S group (all P＜0.05).There were no significant differences in HI or CI between the three groups (all P＞ 0.05).Conclusions The volume variation caused by target volume dehneation on 4DCT images based on different references has little impact on dose distribution in target volume.However,it has substantial impact on radiation doses to the ipsilateral normal breast and lung.
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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.
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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.
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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.
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<p><b>OBJECTIVE</b>To compare the methods of delineating the whole breast target volume based on surface marks, palpation and glandular tissue on CT images, and to explore the contouring criteria after breast-conserving surgery.</p><p><b>METHODS</b>In 15 patients with breast cancer after breast-conserving surgery, the whole breast target was delineated in 3D CT simulation images each by three different methods. The target volume delineated according to anatomical marks were named CTVan, according to breast palpation named CTVpa, and according to glandular mammary tissue showing by CT images named CTVgl. The volumes of CTVan, CTVpa and CTVgl, and the degree of inclusion (DI) and conformal index (CI) between the targets were measured.</p><p><b>RESULTS</b>The mean volumes of CTVan, CTVpa and CTVgl were (792.23 ± 282.25) cm(3), (618.33 ± 295.90) cm(3) and (196.83 ± 117.62) cm(3), respectively. The differences among the three methods were statistically significant (P < 0.001). The difference between CTVan and CTVpa had no statistical significance (P = 0.08), and both the differences between CTVan and CTVgl, and between CTVpa and CTVgl had statistical significance (both P < 0.001). The CI between CTVan and CTVpa (0.644 ± 0.122) was significantly larger than the CI between CTVan and CTVgl (0.264 ± 0.108), and the CI between CTVpa and CTVgl (0.328 ± 0.115)(P < 0.001). The DI of CTVan to CTVpa was 0.709 ± 0.144,DI of CTVgl to CTVan was 0.994 ± 0.005 and DI of CTVgl to CTVpa was 0.989 ± 0.008. The differences of inner, outer, upper and lower boundaries of CTVpa and CTVan were (3.35 ± 7.23) mm, (5.57 ± 13.37) mm, (1.75 ± 11.62) mm, and (11.25 ± 4.07)mm, respectively. The cranial and medial boundaries had a negative correlation with CTVpa (P < 0.05 for all).</p><p><b>CONCLUSIONS</b>The differences among the three methods in the delineation of whole breast target volume are statistically significant. The target volume delineated according to the glandular mammary tissue displayed by CT scan is significantly smaller than that by the other two methods. Combination of breast palpation and anatomical marks may be helpful in delineating the whole breast target volume is relatively reasonable at present.</p>
Subject(s)
Female , Humans , Breast , Pathology , Breast Neoplasms , Diagnostic Imaging , Imaging, Three-Dimensional , Mastectomy, Segmental , Palpation , Tomography, X-Ray ComputedABSTRACT
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.
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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.
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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.
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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.
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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.
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Purpose To investigate the dosimetric differences among RapidArc (RA) plans which were designed on different target volumes in hepatocellular carcinoma (HCC).Methods A total of 10 HCC patients underwent 3D-CT scan under free breathing ( FB),end inspiration hold ( EIH ) associated with active breath coordinator (ABC) and 4D-CT scan.The 4D-CT were sorted into 10 sets of CT images according to respiratory cycle.The gross tumor volume (GTV) was manually contoured on different CT images.The individual internal gross target volume ( IGTV1 ) was obtained from 4D-CT,and the individual margins from GTVFB to IGTV1.IGTV2 were obtained from GTVFB using individual margins.The planned target volumes (PTV-1,PTV-2,PTV-3 and PTV-4 ) were obtained from GTVFB,IGTV1,IGTV2 and GTVEIA applying different margins.The RA plans (RA1,RA2,RA3 and RA4 ) were designed from different PTVs,and for RA1,RA2 and RA3 the simple 358° arc were used,while three 135° arcs were used for RA4.The dosimetric differences were compared.Results The PTV-1 and PTV-3 were larger than PTV-2 and PTV-4; the mean values of PtV-1/PTV-2 and PTV-1/PTV-4 were 2.5 and 1.9,respectively.There were no significant differences in conformal index,homogeneity index,maximum dose,and minimum dose of PTV among 4 RA plans.The irradiation dose of normal liver of RA3 and RA4 were 8.23 Gy and 7.63 Gy respectively,both significantly lower than those of RA1 and RA2 (10.21 Gy,9.62 Gy,x2 =10.68,P ＜0.05 ),and the V30of RA3 and RA4 were 5.24％ and 5.05％ respectively,both significantly lower than those of RA1 and RA2 (7.76％,6.12％,x2 =14.76,P ＜ 0.05 ).There were no significant differences in irradiation doses of stomach and duodenum among different plans.Conclusions Using 4D-CT or ABC technology with RapidArc in HCC can define the target volume accurately and achieve prefect dose distribution sparing more normal liver volume,compared to the traditional margins.4D-CT and ABC play similar roles in sparing normal liver.
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ObjectiveTo investigate the dosimetric difference in the application of RapidArc using 6 and 15 MV X-rays for radiotherapy of multiple hepatic malignancy.MethodsA total of 12 cases with multiple hepatic tumors ( primary 5 cases and secondary 7 cases) were selected.All patients underwent the three dimensional CT simulation in free breathing.For each patient,RapidArc plans with single or two 358° arcs using 6 or 15 MV X-rays were designed respectively,the prescription dose was 2Gy per fraction × 25 fractions.The dosimetric differences were compared among RapidArc plans.ResultsAll of RapidArc plans could meet the clinicalrequirement.There were no significant differences in the conformity index ( CI ),homogeneity index ( HI),the maximum dose and the minimum dose of PTV among RapidArc plans ( P ＞ 0.05).All the CI could get to 0.91 and HI could get to 0.88.In the RapidArc plans with two 358° arcs,the Vs,V10,V15 of normal liver were higher than with single arc,while V20,V25,V30,V35,V40 were lower than with single arc.There were no significant differences in the different radiation dose of normal liver,stomach,duodenum and spinal cord among different plans ( P ＞0.05 ).The monitor units of RapidArc plans using 6 MV X-rays increased 12％ compared to 15 MV averagely.CondusionThe 6 MV X-ray would be selected chiefly in the radiotherapy of multiple haptic tumor using RapidArc with whole arc(s).
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Objective To compare the dosimetric differences of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT) and volumetric modulated arc radiotherapy(V-MAT) for external beam partial breast irradiation.Methods Twelve patients with breast cancer receiving breast-conserving surgery and external beam partial breast irradiation were enrolled.Three different techniques including 3D-CRT,IMRT and V-MAT were designed for each patient.The dosimetry in the target,the dose to the organs at risk(OAR),the MU and delivery time were compared.Results All three plans met the clinical requirement. 3D-CRT showed the worst conformity in target. V-MAT provided the lowest target coverage and homogeneity in target.3D-CRT plans showed the lowest values for the V5,V10,mean dose and the highest values for V30 in the ipsilateral lung.No statistically significant differences were observed in V20 of the ipsilateral lung among three plans.V-MAT showed the lowest values in ipsilateral normal breast volume 15,20 and 25 Gy post-irradiation.For V5,the mean and max dose in heart,the mean dose in contralateral lung and the mean,max dose in thyroid,IMRT and 3D-CRT showed the highest and lowest value respectively(z =-2.94 - -2.09,P ＜ 0.05 ).The MUs in 3D-CRT,IMRT and V-MAT were 417.6 ± 34.4,772.8 ± 54.4 and 631.0 ± 109.0,respectively (z =- 2.93, - 2.76,-2.93,P ＜ 0.05 ). V-MAT significantly reduced the delivery time. Conclusions V-MAT shows significant advantages in reducing the dose in the ipsilateral normal breast and the delivery time compared with 3D-CRT and IMRT.
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Objective To evaluate the accumulated doses to normal tissues and organs at risks (OARs) of patients with lung cancer in radiotherapy plans by using the deformable registration method,and make comparison with the empirical calculation method.Methods Ten patients with lung cancer were analyzed retrospectively.3D-CRT or IMRT plans were designed before treatment. CT to simulator was rescanned and the same treatment plan was redesigned during radiotherapy. Based on the deformable registration method,the Mimvista software was used to calculate the accumulated doses to normal tissues and OARs in two CT images respectively.The empirical estimation algorithm was calculated by the linear relationship between the fractions and the total prescribed dose.Results The target coverage of patients had no significant difference in two plans.There were no significant differences in all the dose volume parameters for normal tissues and OARs,except the mean dose to right lung( t =2.98,P ＜ 0.05 ) when the the same plan was conducted in position-setting and reposition CT images.Conclusions The empirical estimation for the accumulated dose could be used to evaluate the dose and volume parameters for normal tissues and OARs in lung cancer by the same plan.
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ObjectiveTo study the feasibility of RapidArc (RA) associated with active breath coordinator (ABC)for hepatocelluar carcinoma (HCC)radiotherapy comparing of three-dimensional conformal radiotherapy (3DCRT),intensity modulated radiotherapy (IMRT),RA treatment plans in different breath status.Methods12 HCC cases were selected.Three series CT scanning were completed in Free Breathing (FB),End Inspiration Hold (EIH) and End Expiration Hold (EEH) associated with ABC device.3DCRT,IMRT and RA (three 135° arcs) treatment plans were respectively designed on planning target volume (PTV) in different breath status.The dosimetric differences among 3 DCRT,IMRT and RA,among RA plans under different breath status were compared.ResultsThe PTV in FB was larger than in EEHand EIH (160.8 cm3,89.5 cm3,83.1 cm3,F=6.63,P=0.004). The conformity index and homogeneity index of RA plans were better than IMRT and 3DCRT ( 0.92,0.90,0.77,F =72.55,P =0.000 ;0.90,0.89,0.84,F =125.49,P =0.000 ) ;the V20,V30,V40 of normal liver in 3DCRT were higher than IMRT and RA (24％,20％,19％,F=3.56,P =0.032;13％,10％,10％,F=5.74,P =0.004;8％,5％,6％,F =3.72,P =0.027).The normal liver mean dose,V10,V20,V30,V40 of RA plans in FB were higher than in EEH and EIH ( 13.46 Gy,10.25 Gy,9.48 Gy,F =3.627,P =0.038 ;46％,35％,32％,F =2.96,P=0.066;24％,16％,16％,F=3.69,P=0.036;13％,8％,8％,F=4.28,P=0.022;8％,5％,5％,F =2.39,P =0.108 ).The duodenum D5 cm3 of RA in EEH was lower than in FB and EIH (8.78 Gy,19.35 Gy and 11.67 Gy,F =1.56,P =0.224 ).The mean monitor units for 3 DCRT,IMRT,RA was 254.06 MU,626.33 MU and 550.28 MU ( F =147.35,P =0.000 ),while the mean treatment time was 135 s,540 s and 130 s respectively (F =62.83,P =0.000).ConclusionsThe RapidArc applying three 135°arcs with ABC in HCC radiotherapy can achieve better PTV coverage than IMRT with fewer monitor units,shorter treatment time and sparing more normal liver.
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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.