ABSTRACT
Objective To investigate the differences in position and volume between planning target volumes (PTV) based on positron emission tomography?computed tomography (PET?CT) images with an standardized uptake value ( SUV) no less than 2?5, 20% of the maximum SUV ( SUVmax ), or 25% of SUVmax , three?dimensional ( 3D ) CT, and four?dimensional ( 4D ) CT in thoracic esophageal cancer. Methods Eighteen patients with thoracic esophageal cancer sequentially received chest 3DCT, 4DCT, and [18F]fluoro?2?deoxy?D?glucose (FDG) PET?CT scans. PTV3D was obtained by conventional expansion of 3DCT images;PTV4D was obtained by fusion of target volumes from 10 phases of 4DCT images. The internal gross tumor volumes ( IGTV) , IGTVPET2.5 , IGTVPET20%, and IGTVPET25%, were generated based on PET?CT images with an SUV no less than 2?5, 20% of SUVmax , and 25% of SUVmax , respectively. These IGTVs were expanded longitudinally by 3?5 cm and radically by 1 cm to make PTVPET2.5 , PTVPET20%, and PTVPET25%, respectively. Results PTV3D was significantly larger than both PTV4D and PTVPET(P=0?000 -0?044), while there was no significant difference between PTV4D and PTVPET ( P= 0?216 -0?633 ) . The mutual degrees of inclusion ( DIs ) between PTV3D and PTV4D were 0?70 and 0?95, respectively, which were negatively correlated with 3D?Vector ( P=0?039). The mutual DIs between PTVPET2.5, PTVPET20%, and PTVPET25% were 0?74, 0?72, 0?78, 0?73, 0?77, and 0?70, respectively, which showed no correlation with 3D?Vector (P=0?150 -0?822). The mutual DIs between PTV3D and PTVPET were 0?86, 0?84, 0?88, 0?63, 0?67, and 0?59, respectively. Conclusions It is difficult to achieve complete volumetric overlap of PTVs based on 3DCT, 4DCT and PET?CT in thoracic esophageal cancer due to different target volume information. PET scan during free breathing should be used with caution to generate PTVs in thoracic esophageal cancer.
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Objective To compare the position,volume and matching index (MI) of esophagus between quiet end-inspiration and end-expiration in three dimensional CT (3D-CT) assisted with active breathing control (ABC) and the corresponding phases in four dimensional CT (4D-CT).Methods Eleven patients with peripheral lung cancer underwent 4D-CT simulation scan and 3D-CT simulation scans in end-inspiratory hold (CTEIH) and end-expiratory hold (CTEEH) in succession.The 0％ phase was defined as end-inspiratory phase (CT0),while the 50％ phase was defined as end-expiratory phase (CT50).The proximal,mid-,and distal thoracic esophagus were delineated separately on CT0,CT50,CTEIH and CTEEH images.The position,volume and MI of each segment esophagus between CT0 and CTEIH,CT50 and CTEEH were compared.Results In the left-right (x) direction,the position differences in the proximal,mid-,and distal thoracic esophagus between CT0and CTEIH were (-0.02 ±0.16)cm,(0.06 ± 0.26)cm and (0.10 ± 0.33) cm respectively,and in the anterior-posterior (y) direction,the position differences were (0.04 ±0.24)cm,(0.04 ±0.12) cm and (0.08 ±0.15) cm respectively,and the position differences in the same direction were not statistically significant.In the x direction,the position differences of the proximal,mid-,or distal thoracic esophagus between CT50 and CTEEH were (-0.02 ±0.24) cm,(0.12 ± 0.37) cm and (0.26 ± 0.33) cm respectively,and in the y direction,the position differences were (0.03 ±0.21)cm,(0.04 ±0.17)cm and (0.14 ±0.18)cm respectively,and the position differences in x and y directions of proximal and mid-thoracic esophagus between CT50 and CTEEH were not statistically significant,while the position differences in x and y directions of distal thoracic esophagus between CT50and CTEEH were both statistically significant (t =0.025,0.024,P ＜ 0.05).The volumes of the proximal,mid-and distal thoracic esophagus were all larger in CT0and CT50 than those in CTEIHand CTEEH,but without statistical differences.The MIs of the volumes of the proximal,mid-and distal thoracic esophagus between CT0 and CTEIH were (0.50 ± 0.17),(0.50 ± 0.19) and (0.56 ± 0.08),respectively,and those between CT50and CTEEH were (0.50 ±0.16),(0.47 ±0.14) and (0.51 ±0.15),respectively.The MI of each segment esophagus between CT0and CTEIHwas larger than that between CT50 and CTEEH,but without statistical differences.Conclusions The influence of breathing modes on the centroid positions of the proximal,mid-thoracic normal esophagus were not significant and there were spatial mismatches for any segment esophagus between 3D-CT assisted with ABC and 4D-CT.
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Objective To analyze artifacts of gross tumor volume (GTV) and correlated factors in each phase images of four dimensional CT (4DCT) for peripheral lung cancer based on three dimensional CT (3DCT) assisted with active breathing control.Methods Nineteen patients with peripheral lung cancer underwent 3DCT (CTFB) and 4DCT simulation scans during free breathing and then underwent 3DCT simulation scans in end inspiration hold (CTEIH) and end expiration hold (CTEEH) assisted with active breathing control.The relative deviations (Devref) between the reference GTV (GTVref) and the GTVsdelineated based on CTFB (GTVFB) and all phases of 4DCT were calculated respectively.Correlations between GTVref and Devmax and between the tumor motion in the cranio-caudal (CC) direction and Devref were analyzed.Results The maximum median Devref of GTV was GTVFB with 17.83％,and the maximum median Devref of the GTV in all phases of 4DCT was GTV30 with 17.20％.A significant negative correlation was found between GTVEIH and Devmax (r =-0.691,P =0.001).The Devref was crrnelated with the tumor motion amplitude in the CC direction (r =0.323-0.617,P =0.005-0.150).The partial regression coefficient of influence of GTVref size and motion amplitude in the CC direction to the tumor Devmax were -0.500 and 0.583,P =0.002 and 0.001,respectively.Conclusions The GTV artifacts in different phase of 4DCT for the peripheral lung cancer were different to each other,and the influence of target displacement to artifacts was larger than that of target volume,so artifacts could be reduced by controlling breathing to reduce target displacement.
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Objective To evaluate the effect of late course hypofractionated stereotactic radiotherapy (LCHSRT) on locally advanced non small cell lung cancer. Methods From October 1997 to June 1999, 106 patients with locally advanced non small cell lung cancer were randomized into conventional radiotherapy group (CRT) and LCHSRT group. Ninety one patients with complete data were analyzed including 43 patients in CRT group and 48 patients in LCHSRT group. In CRT group, 18 patients were staged Ⅲa and 25 Ⅲb; whereas 19 patients were staged Ⅲa and 29 Ⅲb in LCHSRT group. The initial median dose of 43.5?Gy was given in CRT group to the primary tumor, ipsilateral hilum and mediastinum using AP PA fields with 1.8 2.0?Gy per fraction, then 21.7?Gy was boosted to the residual primary and metastatic regional lymph nodes to the median total dose of 65.2?Gy. In LCHSRT group, after the first 44.4?Gy to the primary tumor, ipsilateral hilar region and mediastinum by AP PA fields with a dose fraction of 1.8 2.0?Gy, noncoplanar arc hypofractionated stereotactic radiotherapy was delivered to the residual primary and metastatic lymph nodes to the total dose of (22.8?5.5)?Gy with 4 7?Gy per fraction treated every other day. Results The radiation pneumonitis rates were 11.6% and 14.6% in CRT group and LCHSRT group, respectively. The radiation pulmonary fibrosis rates diagnosed by CT scan 6 months after radiotherapy were 48.8% and 66.7% in CRT group and LCHSRT group, respectively. The complete regression (CR) rates evaluated by CT scan 3 months after treatment in CRT and LCHSRT group were 30.2% and 63.5%, respectively ( P