ABSTRACT
Objective To compare the size of the internal target volume (ITV),biological target volume (BTV) and internal biological target volume (IBTV) based on PET-CT and 4DCT for primary nonsmall cell lung cancer (NSCLC),as well as try to apply IBTV in radiotherapy planning.Methods A total of 15 patients with NSCLC were sequentially scanned by an axial enhanced 3DCT,4DCT and 18F-FDG PET-CT in the thoracic region.The gross target volumes (GTVs) of ten phases of 4DCT images were contoured,and ITV was obtained by fusion of ten GTVs.BTV based on PET-CT images was determined by the SUV 2.0.The IBTV was defined by fusion of ITV and BTV.Planning target volumes (PTVs) based on ITV,BTV,and IBTV (PITV,PBTV,PIBTV) were obtained by ITV,BTV and IBTV with a 10-mm expansion respectively.The metrics of PIBTV,PITV and PBTV were compared,and the planning parameters of target volumes and risk organs were evaluated.Results There was no significant difference between ITV and BTV,but there was significant difference between IBTV and ITV and BTV (F=22.533,P ＜ 0.05).To include more than 95％ volume of IBTV,it is necessary to expand the margin of 9.0(6.0,12.0)mm based on BTV or 10.00(7.0,12.0)mm based on ITV.There was no significant difference between the two groups (P ＞ 0.05).Dice's similarity coefficient of BTV and ITV was 0.72(0.54,0.79).The intensity modulated radiotherapy plan based on PBTV can guarantee 85.6％ (80.5％,91.2％) of PITV to reach the prescription dose,compared with 80.2％ (74.4％,87.6％) of PBTV by the plan from PITV.Additionally,the conformity index and homogeneity index were not ideal.The dosimetric parameters of PITV and PBTV in the PIBTV plan were much better than those in PBTV-and PITV plan.Conclusions The radiotherapy plan based on PET-CT or 4DCT could not guarantee a reasonable dose distribution of PTV expanded from ITV or BTV.Thus,using IBTV for radiotherapy is advised.
ABSTRACT
Acute lung injury after thoracic surgery is the main cause of perioperative death.Acute lung injury is a complex pathophysiological process involving inflammation,characterized by non cardiogenic hypoxemia and acute exudation of the lungs in imaging.Intraoperative ventilation strategy is the most important factor of postoperative acute lung injury.The core of treatment for postoperative acute lung injury is symptomatic support,and prevention is still the most effective strategy for the management of acute lung injury.In this review,the diagnosis,pathogenesis,risk factors and treatment of post-thoracic acute lung injury are introduced,and the progress of prevention strategy and treatment are discussed and summarized.
ABSTRACT
Objective To analyze the volume and position of the gross tumor volumes (GTV) in primary esophageal cancer based on contrast-enhanced three-dimensional (3D),four-dimensional (4D) and cone beam (CB) computed tomography (CT).Methods A total of thirty-four patients underwent 3D-CT and 4D-CT simulation scans for computer treatment plan and contrast-enhanced CBCT scans were conducted prior to the first treatment.GTV3D,GTV4D50,internal GTVMIP (IGTVMIP) and internal GTVCBCT (IGTVCBCT) were delineated on 3D-CT,4D-CT50 (the end expiratory phase),4D-CTMIP (the maximum intensity projection),and CBCT datasets,respectively.The IGTV10 was defined as 10 respiratory phases GTVs in 4D-CT.To evaluate the difference in position,volume and the volumes encompassed characteristic.Results The significant difference was observed in the volumes [IGTV10 ＞ (IGTVCBCT or IGTVMIP) ＞ (GTV3D or GTV4D50)] regardless of the tumor location.Regarding IGTV10 as the standard volume,the underestimations or overestimations between IGTV10 and IGTVCBCT were larger than that of between IGTV10 and JGTVMIP (t =-8.294--3.192,P ＜ 0.05).However,there was no significant difference between the areas of IGTV10 which excluded in IGTVCBCT and IGTV3D (P ＞ 0.05).The GTV4D50/ IGTVCBCT ratio for upper esophageal tumors was negatively correlated to motion vector (r =-0.756,P ＜ 0.05).The centroid coordinates of IGTVCBCT in AP direction were significantly different from the test volumes (GTV3D,GTV4D50,IGTVMIP and IGTV10) (t =-3.559--2.435,P ＜ 0.05).The IGTV10/IGTVCBCT ratio was positively correlated to motion vector (r =0.695,P ＜ 0.05) for middle esophageal tumors.The centroid coordinates of IGTVCBCT were significantly different IGTV10 (t =2.201,P ＜0.05) in AP direction.For distal esophageal tumors,the significant difference was observed in the centroid coordinate between IGTVcBcT and IGTVMIP (t =-2.365,P ＜ 0.05) in LR direction.The percentage of IGTV10 excluded the IGTVcBcT were significantly correlated to the motion vector (r =0.540,0.678,P ＜ 0.05) for both middle and distal esophageal tumors.The mean MI value of IGTVCBCT to the other four test volumes ranged from 0.65 to 0.72.Conclusions CBCT has much motion information than 3D-CT but less than IGTV10.CBCT was similar to MIP images based on respiration motion.However,the target motion information encompassed in CBCT and MIP images cannot be exchanged to each other.
ABSTRACT
Objective To compare the normal thickness of the esophageal wall measured by contrast?enhanced three?dimensional ( 3DCT ) , four?dimensional ( 4DCT ) , and cone beam computed tomography ( CBCT) ,and to provide a basis for target volume delineation in esophageal cancer. Methods From 2009 to 2016,thoracic contrast?enhanced 3DCT and 4DCT simulations were performed in 50 patients with lung cancer or metastatic lung cancer. Contrast?enhanced CBCT scans were acquired during the first three?dimensional conformal radiotherapy. The normal esophageal wall was contoured on 3DCT images, the end?exhalation phase of 4DCT images ( 4DCT50 ) , the maximum intensity projection of 4DCT images (4DCTMIP),and CBCT images. The wall thickness was measured on each segment and the average thickness of esophageal wall was obtained. Comparison of the thickness of a fixed segment of esophageal wall between different CT images was made by paired t test. Comparison of thickness on the same type of CT images between different segments of esophageal wall was made by one?way analysis of variance. Results For the thoracic and intra?abdominal segments,there was no significant difference in the thickness of esophageal wall between 3DCT and 4DCT50 images ( P= 0?056?0?550 );however, the thickness of esophageal wall was significantly smaller on 3DCT images than on 4DCTMIP or CBCT images (P=0?000?0?004).For the upper and middle thoracic segments,the thickness of esophageal wall was significantly larger on CBCT images than on 4DCTMIP images ( P= 0?008, P= 0?001 ) . On 3DCT, 4DCT50 , and 4DCTMIP images, the thickness of esophageal wall was significantly larger in the lower thoracic segment than in the upper or middle thoracic segments ( P=0.008~0?041);the intra?abdominal segment had a significantly larger thickness of esophageal wall than the thoracic segments ( all P=0?000 ) . There was no significant difference in wall thickness on CBCT images between three thoracic segments ( P=0.088~0?945) . Conclusions A uniform criterion can be adopted to judge the normal thickness of esophageal wall in gross tumor volume ( GTV ) delineation on 3DCT and 4DCT50 images for thoracic esophageal cancer. However,caution should be taken when 5 mm is used as a criterion for normal thickness of esophageal wall in GTV delineation on 4DCTMIP and CBCT images.