scholarly journals Impact of Four-Dimensional Cone-Beam Computed Tomography on Target Localization for Gastric Mucosa-Associated Lymphoid Tissue Lymphoma Radiotherapy: Reducing Planning Target Volume Margin

2020 ◽  
Author(s):  
Yoshinobu Shimohigashi ◽  
Ryo Toya ◽  
Tetsuo Saito ◽  
Yumiko Kono ◽  
Yasuhiro Doi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Gastric Mucosa ◽  
Planning Target Volume ◽  
Lymphoid Tissue ◽  
Target Volume ◽  
Target Localization ◽  
Cone Beam ◽  
Ptv Margin ◽  
Dimensional Cone

Abstract Background: Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the whole stomach with optimal planning target volume (PTV) margins that account for variations in stomach volume, respiratory movement, and patient set-up error. In this study, we evaluated whether the use of four-dimensional cone-beam computed tomography (4D-CBCT) reduces the PTV margin.Methods: Eight patients underwent radiotherapy with 15 fractions of gastric MALT lymphoma using 4D-CBCT. Structures with PTV margins of 5–30 mm (5 mm intervals) from the internal target volume of the stomach defined based on the 4D-CT images were generated. For the target localization, we performed matching based on skin marking (skin matching), bone anatomy (bone matching), and stomach anatomy (4D soft-tissue matching) based on registration between planning CT and 4D-CBCT images from 10 phases. For each patient, we calculated the covering ratio (CR) of the stomach with variable PTV margins, based on the 4D-CBCT images, with a total of 150 phases [CR (%) = (number of covering phases / 150 phases) × 100], for three target localization methods. We compared the CR values of the different target localization methods and defined a minimal PTV margin with an average CR of ≥ 95 % for all patients as optimal.Results: The average CR for all patients increased from 17.9 % to 100 %, 19.6 % to 99.8 %, and 33.8 % to 100 %, in the skin, bone, and 4D soft-tissue matchings, respectively, as the PTV margins increased from 5 to 30 mm. The CR obtained by 4D soft-tissue matching was superior to that obtained by skin (P = 0.013) and bone matching (P = 0.008) for a PTV margin of 15 mm. The optimal PTV margins were 20 mm (average CR: 95.2 %), 25 mm (average CR: 99.1 %), and 15 mm (average CR: 98.0 %) for the skin, bone, and 4D soft-tissue matchings, respectively.Conclusions: This study demonstrates that the use of 4D-CBCT reduces the PTV margin when applying 4D soft-tissue matching, compared to skin and bone matchings. Additionally, bone matching does not reduce the PTV margin as compared with traditional skin matching.

scholarly journals Impact of four-dimensional cone-beam computed tomography on target localization for gastric mucosa-associated lymphoid tissue lymphoma radiotherapy: reducing planning target volume

2020 ◽  
Author(s):  
Yoshinobu Shimohigashi ◽  
Ryo Toya ◽  
Tetsuo Saito ◽  
Yumiko Kono ◽  
Yasuhiro Doi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Gastric Mucosa ◽  
Cone Beam Computed Tomography ◽  
Planning Target Volume ◽  
Lymphoid Tissue ◽  
Target Volume ◽  
Target Localization ◽  
Cone Beam ◽  
Dimensional Cone

Abstract Background: Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the entire stomach with planning target volume (PTV) that accounts for variations in stomach volume, respiratory movement, and patient set-up error. In this study, we evaluated whether the use of four-dimensional cone-beam computed tomography (4D-CBCT) reduces the PTV. Methods: Eight patients underwent radiotherapy with 15 fractions of gastric MALT lymphoma using 4D-CBCT. PTV structures of 5–30 mm margins (5 mm intervals) from the clinical target volume (CTV) delineated based on the 4D-CT images (CTV-4D) were generated. For the target localization, we performed matching based on skin marking (skin matching), bone anatomy (bone matching), and stomach anatomy (4D soft-tissue matching) based on registration between planning CT and 4D-CBCT images from 10 phases. For each patient, we calculated the covering ratio (CR) of the stomach with variable PTV structures, based on the 4D-CBCT images, with a total of 150 phases [CR (%) = (number of covering phases / 150 phases) × 100], for three target localization methods. We compared the CR values of the different target localization methods and defined the PTV with an average CR of ≥ 95 % for all patients. Results: The average CR for all patients increased from 17.9 % to 100 %, 19.6 % to 99.8 %, and 33.8 % to 100 %, in the skin, bone, and 4D soft-tissue matchings, respectively, as the PTV structures increased from 5 to 30 mm. The CR obtained by 4D soft-tissue matching was superior to that obtained by skin (P = 0.013) and bone matching (P = 0.008) for a PTV structure of 15 mm margin. The PTV required an additional margin of 20 mm (average CR: 95.2 %), 25 mm (average CR: 99.1 %), and 15 mm (average CR: 98.0 %) to CTV-4D for the skin, bone, and 4D soft-tissue matchings, respectively. Conclusions: This study demonstrates that the use of 4D-CBCT reduces the PTV when applying 4D soft-tissue matching, compared to skin and bone matchings. Additionally, bone matching does not reduce the PTV as compared with traditional skin matching.

scholarly journals Impact of four-dimensional cone-beam computed tomography on target localization for gastric mucosa-associated lymphoid tissue lymphoma radiotherapy: reducing planning target volume

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Yoshinobu Shimohigashi ◽  
Ryo Toya ◽  
Tetsuo Saito ◽  
Yumiko Kono ◽  
Yasuhiro Doi ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Soft Tissue ◽  
Gastric Mucosa ◽  
Cone Beam Computed Tomography ◽  
Planning Target Volume ◽  
Lymphoid Tissue ◽  
Target Volume ◽  
Target Localization ◽  
Cone Beam ◽  
Dimensional Cone

Abstract Background Radiotherapy of gastric mucosa-associated lymphoid tissue (MALT) lymphoma should be delivered to the entire stomach with planning target volume (PTV) that accounts for variations in stomach volume, respiratory movement, and patient set-up error. In this study, we evaluated whether the use of four-dimensional cone-beam computed tomography (4D-CBCT) reduces the PTV. Methods Eight patients underwent radiotherapy with 15 fractions of gastric MALT lymphoma using 4D-CBCT. PTV structures of 5–30 mm margins (5 mm intervals) from the clinical target volume (CTV) delineated based on the 4D-CT images (CTV-4D) were generated. For the target localization, we performed matching based on skin marking (skin matching), bone anatomy (bone matching), and stomach anatomy (4D soft-tissue matching) based on registration between planning CT and 4D-CBCT images from 10 phases. For each patient, we calculated the covering ratio (CR) of the stomach with variable PTV structures, based on the 4D-CBCT images, with a total of 150 phases [CR (%) = (number of covering phases/150 phases) × 100], for three target localization methods. We compared the CR values of the different target localization methods and defined the PTV with an average CR of ≥ 95% for all patients. Results The average CR for all patients increased from 17.9 to 100%, 19.6 to 99.8%, and 33.8 to 100%, in the skin, bone, and 4D soft-tissue matchings, respectively, as the PTV structures increased from 5 to 30 mm. The CR obtained by 4D soft-tissue matching was superior to that obtained by skin (P = 0.013) and bone matching (P = 0.008) for a PTV structure of 15 mm margin. The PTV required an additional margin of 20 mm (average CR: 95.2%), 25 mm (average CR: 99.1%), and 15 mm (average CR: 98.0%) to CTV-4D for the skin, bone, and 4D soft-tissue matchings, respectively. Conclusions This study demonstrates that the use of 4D-CBCT reduces the PTV when applying 4D soft-tissue matching, compared to skin and bone matchings. Additionally, bone matching does not reduce the PTV as compared with traditional skin matching.

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