Comparison of three methods to delineate internal gross target volume of the primary hepatocarcinoma based on four-dimensional CT simulation images / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To compare the position and magnitude of internal target gross volume (IGTV) of primary hepatocarcinoma delineated by three methods based on four-dimensional computed tomography (4D-CT) and to investigate the relevant factors affecting the position and magnitude.</p><p><b>METHODS</b>Twenty patients with primary hepatocarcinoma after transcatheter arterial chemoembolization (TACE) underwent big bore 4D-CT simulation scan of the thorax and abdomen using a real-time position management (RPM) system for simultaneous record of the respiratory signals. The CT images with respiratory signal data were reconstructed and sorted into 10 phase groups in a respiratory cycle, with 0% phase corresponding to end-inhale and 50% corresponding to end-exhale. The maximum intensity projection (MIP) image was generated. IGTVs of the tumor were delineated using the following three methods: (1) The gross tumor volume (GTV) on each of the ten respiratory phases of the 4D-CT image set was delineated and fused ten GTV to produce IGTV10; (2) The GTVs delineated separately based on 0% and 50% phase were fused to produce IGTV(IN+EX); (3) The visible tumor on the MIP image was delineated to produce IGTV(MIP). Twenty patients were divided into groups A and B based on the location of the target center,and were divided into groups C and D based on the tumor maximum diameter. The patients were divided into groups E and F based on the three-dimensional (3D) motion vector of the target center. The position of the target center, the volume of target, the degree of inclusion (DI) and the matching index (MI) were compared reciprocally between IGTV10, IGTV(IN+EX) and IGTV(MIP), and the influence of the tumor position and 3D motion vector on the related parameters were compared based on the grouping.</p><p><b>RESULTS</b>The average differences between the position of the center of IGTVs on direction of X, Y and Z axes were less than 1.5 mm, and the difference was statistically not significant. The volume of IGTV10 was larger than that of IGTV(IN+EX), but the difference was not significant (t = 0.354, P = 0.725). The volume of IGTV10 was larger than that of IGTV(MIP) but the difference was not significant (t = -0.392, P = 0.697). The ratio of IGTV(IN+EX) to IGTV10 was 0.75 +/- 0.15 and the ratio of IGTV(MIP) to IGTV10 was 0.78 +/- 0.14. The DI of IGTV(IN+EX) in IGTV10 was (74.85 +/- 15.09)% and that of IGTV(MIP) in IGTV10 was (68.87 +/- 13.69)%. The MI between IGTV10 and IGTV(IN+EX), IGTV10 and IGTV(MIP) were 0.75 +/- 0.15 and 0.67 +/- 0.13, respectively. The median of ratio of IGTV(IN+EX)/ IGTV10 was 0.57 in group A versus 0.87 in group B, statistically with a significant difference between the groups A and B (Z = -3.300,P = 0.001). The median of ratio of IGTV(MIP)/IGTV10 was 0.51 in the group A and 0.72 in group B, with a significant difference between the groups A and B (Z = -3.413, P = 0.001). The median of ratio of IGTV(IN+EX)/IGTV10 was 0.79 in group C versus 0.74 in group D, with a difference not significant (Z = -0.920, P = 0.358). The median of ratio of IGTV(MIP)/IGTV10 was 0.85 in group C versus 0.80 in group D, with a non-significant difference (Z = -0.568, P = 0.570). The median of ratio of IGTV(IN+EX)/IGTV10 was 0.87 in group E versus 0.68 in group F, with a significant difference between the two groups (Z = -2.897, P = 0.004). The median of ratio of IGTV(MIP)/IGTV10 was 0.85 in the group E versus 0.81 in the group F, with a non-significant difference (Z = -0.568, P = 0.570).</p><p><b>CONCLUSIONS</b>The center displacement of the IGTVs delineated separately by the three techniques based on 4D-CT images is not obvious. IGTV(IN+EX) and IGTV(MIP) can not replace IGTV10, however, IGTV(IN+EX) is more close to IGTV10 comparing with IGTV(MIP). The ratio of IGTV10 and IGTV(MIP) is correlated to the 3D motion vector of the tumor. When the tumor is situated in the upper part of the liver and with a 3D motion vector less than 9 mm, IGTV10 should be the best IGTV.</p>

Displacement of the silver clips in surgical cavity based on four-dimensional CT images for patients undertaking external-beam partial breast irradiation after breast-conserving surgery / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the displacement of the selected clips and the center of the geometry consisted of all the clips in the surgical cavity measured on the basis of four-dimensional computed tomography (4D-CT) simulation images.</p><p><b>METHODS</b>Fourteen breast cancer patients after breast-conserving surgery were recruited for external beam partial-breast irradiation (EB-PBI), and received large aperture CT simulation. The 4D-CT image data sets were collected when the patient was in the free breathing state. Using the Varian Eclipse treatment planning system, the selected four clips in the cavity were separately delineated on the CT images from 10 phases of the breath cycle, and all of the clips in the cavity were marked to obtain the geometry. Then the displacement of the four selected clips and the center of the geometry in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. The differences of the displacement were compared.</p><p><b>RESULTS</b>The displacements in the AP and SI directions were always greater than the displacement in LR direction for the same selected clip. The difference of the displacements in the same direction of the different selected clips was not statistically significant (P>0.05). The displacements of the geometry center consisted of all of the clips in the LR, AP, SI directions were (1.34±0.39) mm, (2.01±1.02) mm and (1.89±1.03) mm, respectively, and the difference of the displacements between LR and AP, LR and SI were all statistically significant (P<0.05). In the same directions (LR, AP and SI), the displacement of geometry center was always greater than the displacement of the selected clips, and the difference except SI direction was all statistically significant (P<0.05). In the SI direction, the association between the displacement of geometry center and the upper clip, geometry center and the lower clip was statistically significant (P<0.05).</p><p><b>CONCLUSION</b>When the target for EB-PBI is defined on the basis of 4D-CT simulation images, the displacement of the selected clips at the border of the surgical cavity is not qualified to substitute the displacement of the target defined basing on all of the clips in the surgical cavity.</p>