ABSTRACT
Objective To evaluate the respiration-induced target volume motion in 3D-CRT for mid-thoracic esophageal carcinoma in order to guide the radiation oncologist to choose the expansion marginfor ITV.Methods Ten patients with mid-thoracic esophageal carcinoma were scanned by multi-spiral CTsimulator respectively in free breathing(FB),breath.hold after normal inspiration and expiration(IBH and EBH)with the same scanning range.Then the CT images of three series were transfefred to the treatmentplanning system.The target volume was outlined following the same standard.The motion of the centerpoint of GTV,the center point of each slice of GTV and the edge of the GTV in selected slice weremeasured respectively to obtain the comprehensive value of GTV motion。in order to find the appropriate IMvalue according to the 95％confidence interval of the GTV motion.Results①The GTV motion betweenIBH and EBH was(0.19±0.16)cm in the left.right direction,(0.54±0.19)cm in the cranial andcaudal irection.and(0.16±0.14)cm in anterior.posterior directions for the center of GTV,.For thecenter point of each slice of GTV.they ere(0.19±0.15)cm,(0.54±0.16)cm,(0.16±0.13)cm in three directions above.respectively.For the edge of the GTV in selected slice.they were(0.26±0.19)cm,(0.54±0.18)cm,(0.24±0.19)cm,respectively.The comprehensive value of GTV motion between IBH and EBH was(0.23±0.17)cm,(0.54±0.17)cm,(0.21±0.17)cm.respectively.The 95％confidence interval was 0.21-0.25 cm.0.53-0.56 cm and 0.19-0.22 cm in three directions.②The direction of GTV motion：No motion was noticed in 8.2％.while 73.3％to the right side and 18.5％to the left side in the left-right direction when IBH were compared with EBH.100％were moved to caudal in the the cranial and caudal direction[(0.54±0.17)cm].In the anterior-posterior direction,no motion was noticed in 8.2％,while 16.6％to the posterior and 75.2％to the anterior when IBH were compared with EBH.③The GTV motion was correlated with the vafiance of 1ung volumes in IBH-EBH(r=0.683,P=0.032)and not with GTV volume and length.Conclusions Respiration can induce target volume motion in 3 DCRT for mid-thoracic esophageal carcinoma.Compared to EBH.the GTV tends to move to the caudal,the anterior and the ight side in IBH.
ABSTRACT
Objective To evaluate the respiration-induced dosimetric variance in 3DCRT for midthoracic esophageal carcinoma, in order to guide the radiation oncologist to choose the expansion margin. Methods Ten patients with mid-thoracic esophageal carcinoma were scanned by multi-spiral CT simulator respectively in free breathing ( FB), breath-hold after normal inspiration and expiration ( IBH and EBH )with the same scanning range. Then the CT images of three series were transferred to the treatment planning system. The target volume was outlined following the same standard. Plan1 was designed in the images of FB and transported completely to the images of IBH and EBH as Plan2 and Plan3 respectively to observe the dosimetric variance in target volume. Results For GTV, there was a statistical difference only in V100 of the three plans ( H = 6.423, P = 0.040 ) and no significant difference was found in other indexes. For CTV, the V100 and V95 were better in Plan1 (F=3.992, P=0.030; H=9.920, P=0.007) and no significant difference was found in other indexes. While ()TV, the Dmin, V100 and V95 was better in Plan1 ( F = 3.677, P = 0.039; F = 4.539, P = 0.020; H = 6.846, P = 0.033 ) and no significant difference was found in other indexes. There were no significant differences in all the indexes for the spinal cord and lung in the three plans. Conclusions The change in dose distribution was not so much with the standard expansion. It can meet the needs of clinical treatment.