PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

PURPOSE: To see the gross tumor volume (GTV) dependency according to the phase selection and reconstruction methods, we measured and analyzed the changes of tumor volume and motion at each phase in 20 cases with lung cancer patients who underwent image-guided radiotherapy. MATERIALS AND METHODS: We retrospectively analyzed four-dimensional computed tomography (4D-CT) images in 20 cases of 19 patients who underwent image-guided radiotherapy. The 4D-CT images were reconstructed by the maximum intensity projection (MIP) and the minimum intensity projection (Min-IP) method after sorting phase as 40%–60%, 30%–70%, and 0%–90%. We analyzed the relationship between the range of motion and the change of GTV according to the reconstruction method. RESULTS: The motion ranges of GTVs are statistically significant only for the tumor motion in craniocaudal direction. The discrepancies of GTV volume and motion between MIP and Min-IP increased rapidly as the wider ranges of duty cycles are selected. CONCLUSION: As narrow as possible duty cycle such as 40%–60% and MIP reconstruction was suitable for lung cancer if the respiration was stable. Selecting the reconstruction methods and duty cycle is important for small size and for large motion range tumors.
Four-Dimensional Computed Tomography* ; Humans ; Lung Neoplasms* ; Lung* ; Methods* ; Radiotherapy, Image-Guided ; Range of Motion, Articular ; Respiration ; Retrospective Studies ; Tumor Burden*

OBJECTIVETo investigate the dosimetric benefit of 4D-CT in the planning target volume (PTV) definition process compared with conventional PTV definition using general margin in radiotherapy of lung cancer.

METHODSA set of 4D-CT images and multiphase helical CT scans were obtained in 10 patients with lung cancer. The radiotherapeutic plans based on PTV determined by 4D-CT and in addition of general margin were performed, respectively. The 3D motion of the centroid of GTV and the 3D spatial motion vectors were calculated. The differences of the two kinds of PTVs, mean lung dose (MLD), V5,V10,V15,V20 of total lung, mean heart dose (MHD), V30 and V40 of heart, D99 and D95 were compared, and the correlation between them and the 3D spatial motion vector was analyzed.

RESULTSThe PTV4D in eight patients were smaller than PTVconv, with a mean reduction of (13.0 ± 8.0)% (P = 0.018). In other two patients, whose respiration motion was great, PTV4D was larger than PTVconv. The mean 3D spatial motion vector of GTV centroid was (0.78 ± 0.72)cm. By using 4D-CT, the mean reduction of MLD was (8.6 ± 9.9)% (P = 0.037). V5, V10, V15, V20 of total lung were decreased averagely by (7.2 ± 10.5)%, (5.5 ± 8.9)%, (6.5 ± 8.4)% and (5.7 ± 7.4)%, respectively (P < 0.05 for all). There was a significant positive correlation between PTV4D/PTVconv and the 3D spatial motion vector of the GTV centroid (P = 0.008). A significant inverse correlation was found between D994D/D99conv and the 3D spatial motion vector of the GTV centroid (P = 0.002). D994D/D99conv, (MLDconv-MLD4D) /MLDconv, total lung (V5conv-V54D)/V5conv, total lung (V10conv-V104D)/V10conv, (MHDconv-MHD4D)/MHDconv, heart (V30conv-V304D)/V30conv were inversely correlated with PTV4D/PTVconv (P < 0.05 for all).

CONCLUSIONS4D-CT can be used to evaluate the respiration motion of lung tumor accurately. The 4D-CT-based PTV definition and radiotherapeutic planing can reduce the volume of PTV in patients with small respiration motion, increase the intra-target dose, and decrease the dose of normal tissue sequentially. For patients with large respiration motion, especially those more than 1.5-2 cm, this method can avoid target miss, meanwhile, not increase the dose of normal tissue significantly.

Four-Dimensional Computed Tomography ; methods ; Humans ; Lung ; physiopathology ; Lung Neoplasms ; radiotherapy ; Movement ; Radiometry ; Radiotherapy Planning, Computer-Assisted ; methods ; Respiration ; Tomography, X-Ray Computed ; methods

Four-dimensional cone beam CT (4D-CBCT) imaging can provide accurate location information of real-time breathing for imaging-guided radiotherapy. How to improve the accuracy of 4D-CBCT reconstruction image is a hot topic in current studies. PICCS algorithm performs remarkably in all 4D-CBCT reconstruction algorithms based on CS theory. The improved PICCS algorithm proposed in this paper improves the prior image on the basis of the traditional PICCS algorithm. According to the location information of each phase, the corresponding prior image is constructed, which completely eliminates the motion blur of the reconstructed image caused by the mismatch of the projection data. Meanwhile, the data fidelity model of the proposed method is consistent with the traditional PICCS algorithm. The experimental results showed that the reconstructed image using the proposed method had a clearer organization boundary compared with that of images reconstructed using the traditional PICCS algorithm. This proposed method significantly reduced the motion artifact and improved the image resolution.
Algorithms ; Cone-Beam Computed Tomography ; methods ; Four-Dimensional Computed Tomography ; Humans ; Image Processing, Computer-Assisted ; Organ Motion ; Radiographic Image Enhancement ; instrumentation ; methods ; Respiration

Cone-Beam Computed Tomography ; methods ; Four-Dimensional Computed Tomography ; methods ; Humans ; Image Processing, Computer-Assisted ; methods ; Magnetic Resonance Imaging ; methods ; Multimodal Imaging ; methods ; Neoplasms ; diagnosis ; diagnostic imaging ; radiotherapy ; Positron-Emission Tomography ; Radiotherapy, Computer-Assisted ; methods ; Tomography, X-Ray Computed

OBJECTIVETo explore the differences in volume and localization of the internal gross target volume and planning target volume delineated by clips and/or seroma based on four-dimensional computed tomography (4D-CT) during free-breathing in breast cancer patients after breast conserving surgery.

METHODSFifteen breast cancer patients after breast-conserving surgery (BCS) were recruited for external-beam partial breast irradiation (EB-PBI). On the ten sets CT images, the gross tumor volumes (GTV) formed by the clips, the seroma, and both the clips and seroma were delineated and defined as GTVc, GTVs and GTVc+s, respectively. Ten GTVc, GTVs and GTVc+s on the ten sets CT images produced the IGTVc, IGTVs, IGTVc+s. The PTVc, PTVs, PTVc+s were created by adding 15 mm to the IGTVc, IGTVs, IGTVc+s, respectively. The IGTV and PTV volume and distance between the centers of IGTVc, IGTVs, IGTVc+s and PTVc, PTVs, PTVc+s were all recorded. Conformity index (CI) and degree of inclusion (DI) were calculated for IGTV/IGTV and PTV/PTV, respectively.

RESULTSThe volume of IGTVc+s[(35.73 ± 19.77) cm³] was significantly larger than the IGTVc [(28.35 ± 17.54) cm³] and IGTVs [(24.19 ± 21.53) cm³] (P < 0.05), and the volume of PTVc+s [(191.59 ± 69.74) cm³] was significantly larger than that of the PTVc [(161.53 ± 61.07) cm³] and PTVs [(148.98 ± 62.22)cm³] (P < 0.05). There were significant differences between the DIs of IGTVc in IGTVc+s and IGTVc+s in IGTVc, the DIs of IGTVs in IGTVc+s and IGTVc+s in IGTVs, the DIs of PTVc in PTVc+s and PTVc+s in PTVc, and the DIs of PTVs vs. PTVc+s and PTVc+s in PTVs (P < 0.05 for all). The CI of IGTVc/IGTVc+s (0.63 ± 0.14) and the CI of IGTVs/IGTVc+s (0.54 ± 0.17) were significant larger than that of the CI of IGTVc/IGTVs (0.40 ± 0.14)(P < 0.05). There were non-significant differences among the CI of PTVc/PTVs, PTVc/PTVc+s and PTVs/PTVc+s (0.73 ± 0.12, 0.78 ± 0.13 vs. 0.75 ± 0.17). The DIs and CIs of IGTV/IGTV and PTV/PTV were negatively correlated with their centroid distance (P < 0.05).

CONCLUSIONSThere are volume difference and spatial mismatch between the target volumes delineated on the basis of surgical clips and seroma. The DI and CI between the PTVs are larger than that between the IGTV. External-beam partial breast irradiation should be implemented based on the PTV that is defined based on both seroma and surgical clips.

Breast Neoplasms ; diagnostic imaging ; radiotherapy ; Female ; Four-Dimensional Computed Tomography ; Humans ; Mastectomy, Segmental ; methods ; Radiotherapy Dosage ; Respiration ; Seroma ; diagnostic imaging ; radiotherapy ; Surgical Instruments

OBJECTIVETo explore the vascular structure of the deep inferior epigastric artery perforator with the four-dimensional computed tomography (CT) angiography.

METHODS10 abdominal specimens harvested from fresh cadavers were cannulated with trocar and injected with contrast medium in the deep inferior epigastric artery at different levels, including the deep inferior epigastric artery, its bifurcations, the lateral or medial large perforators. During the perfusion of the contrast medium in the flap, the flap was scanned by three-dimensional CT (four-dimensional defined as three dimensional CT plus time). The CT data were sent to CT workstation and the images were processed and reformatted.

RESULTSThe deep inferior epigastric artery perforator terminates in the subdermal vascular plexus, with bifurcating superior to the Scarpa fascia and under the skin. The anastomosis in the abdominal midline occurs in the subdermal vascular plexus. The blood flow distributes in two ways, one is the subdermal vascular plexus, the other is the existed vascular structure. The zone overlying the rectus muscle in the pedicle side has the best blood supply, the other adjacent zone on the ipsilateral side of the abdomen, the zone overlying the contralateral rectus muscle and the zone lateral to the contralateral rectus muscle has declining perfusion.

CONCLUSIONSThe four-dimensional CT is a useful method to study the vascular structure of the deep inferior epigastric artery perforator in the superficial fascia.

Abdominal Wall ; blood supply ; Angiography ; methods ; Epigastric Arteries ; diagnostic imaging ; Female ; Four-Dimensional Computed Tomography ; Humans ; Male ; Surgical Flaps ; blood supply

Four-Dimensional Computed Tomography ; Humans ; Liver Neoplasms ; diagnostic imaging ; radiotherapy ; Lung Neoplasms ; diagnostic imaging ; radiotherapy ; Male ; Prostatic Neoplasms ; diagnostic imaging ; radiotherapy ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Intensity-Modulated ; methods

OBJECTIVETo measure the intrafraction displacement of the mediastinal metastatic lymph nodes of non-small cell lung cancer (NSCLC) based on four-dimensional computed tomography (4D-CT), and to provide the basis for the internal margin of metastatic mediastinal lymph nodes.

METHODSTwenty-four NSCLC patients with mediastinal metastatic lymph nodes confirmed by contrast enhanced CT (short axis diameter ≥ 1 cm) were included in this study. 4D-CT simulation was carried out during free breathing and 10 image sets were acquired. The mediastinal metastatic lymph nodes and the dome of ipsilateral diaphragma were separately delineated on the CT images of 10 phases of breath cycle, and the lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal station. Then the displacements of the lymph nodes in the left-right, anterior-posterior, superior-inferior directions and the 3-dimensional vector were measured. The differences of displacement in three directions for the same group of metastatic lymph nodes and in the same direction for different groups of metastatic lymph nodes were compared. The correlation between the displacement of ipsilateral diaphragma and mediastinal lymph nodes was analyzed in superior-inferior direction.

RESULTSThe displacements in left-right, anterior-posterior and superior-inferior directions were (2.24 ± 1.55) mm, (1.87 ± 0.92) mm and (3.28 ± 2.59) mm for the total (53) mediastinal lymph nodes, respectively. The vectors were (4.70 ± 2.66) mm, (3.87 ± 2.45) mm, (4.97 ± 2.75) mm and (5.23 ± 2.67) mm for the total, upper, middle and lower mediastinal lymph nodes, respectively. For the upper mediastinal lymph nodes, the displacements in left-right, anterior-posterior and superior-inferior directions showed no significant difference between each other (P > 0.05). For the middle mediastinal lymph nodes, the displacements merely in anterior-posterior and superior-inferior directions showed significant difference (P = 0.005), while the displacements were not significantly different in the left-right and anterior-posterior, left-right and superior-inferior directions (P > 0.05). The displacements of the total and the lower mediastinal lymph nodes in left-right and superior-inferior, or anterior-posterior and superior-inferior directions were significantly different (P < 0.05), but was not significantly different in left-right and anterior-posterior directions (P > 0.05). The displacements of different group of mediastinal lymph nodes in a single direction or vector showed no significant difference (P > 0.05). In the superior-inferior direction, the correlation between the displacements of ipsilateral diaphragma and mediastinal lymph nodes were not statistically significant (P > 0.05).

CONCLUSIONSDuring free breathing, the differences between the intrafractional displacement of mediastinal metastatic lymph nodes in the same direction and its station were not statistically significant. The displacements of the total mediastinal metastatic lymph nodes in the superior-inferior direction were greater than that in the left-right and anterior-posterior directions, especially for the middle and lower mediastinal metastatic lymph nodes. There was no significant correlation between the displacements of ipsilateral diaphragma and the mediastinal metastatic lymph nodes in the superior-inferior direction, so it was unreasonable to estimate and predict the displacement of mediastinal metastatic lymph nodes by the displacement of ipsilateral diaphragma.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Non-Small-Cell Lung ; diagnostic imaging ; pathology ; Female ; Four-Dimensional Computed Tomography ; methods ; Humans ; Lung Neoplasms ; diagnostic imaging ; pathology ; Lymph Nodes ; diagnostic imaging ; pathology ; Male ; Mediastinum ; diagnostic imaging ; pathology ; Middle Aged ; Movement ; Respiration

Anatomic Landmarks ; diagnostic imaging ; Cone-Beam Computed Tomography ; methods ; Esophageal Neoplasms ; diagnostic imaging ; pathology ; radiotherapy ; Esophagus ; diagnostic imaging ; pathology ; Fiducial Markers ; Four-Dimensional Computed Tomography ; methods ; Humans ; Image Processing, Computer-Assisted ; methods ; Movement ; Radiotherapy Planning, Computer-Assisted ; methods ; Radiotherapy, Conformal ; methods ; Radiotherapy, Intensity-Modulated ; methods ; Respiration