title: Defining the target volume for post-operative radiotherapy after D2 dissection in gastric cancer by CT-based vessel-guided delineation.
abstract: OBJECTIVE
  To determine the recurrent nodal gross tumor volume (rnGTV) based on CT-guided vascular structure to refine the clinical target volume (CTV) delineation in postoperative radiotherapy for advanced gastric cancer following radical gastrectomy with D2 dissection.
  
  
  METHODS
  We retrospectively reviewed follow-up images from 91 patients with their first regional recurrence after D2 dissection in stage III gastric cancer with N3 disease. We defined rnGTV as recurrent nodes shown in follow-up CT images, in which one diagnostic radiologist with specialty of gastrointestinal tract investigated. We drew rnGTVs at the equivalent location based on the same vessels of reference comparing CT images to recurrence CT images.
  
  
  RESULTS
  We propose vessel-based locations of rnGTVs on CT images with axial and coronal views. We show different patterns of regional recurrence according to the location of primary gastric cancer using CT and digitally reconstructed radiograph (DRR) images. Frequently recurred sites, overlapped by more than five rnGTVs, are depicted in a DRR image.
  
  
  CONCLUSIONS
  This study suggests vessel-based delineations of rnGTVs on CT images depending on nodal recurrence sites from follow-up images after D2 lymphadenectomy. Our results could help reduce the inter-observer variation of CTV delineation after D2 dissection in gastric cancer.
authors.affiliation: Department of Radiation Oncology, Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Hong In
authors.initials: HI
authors.lastname: Yoon
authors.forename: Jee Suk
authors.initials: JS
authors.lastname: Chang
authors.forename: Joon Seok
authors.initials: JS
authors.lastname: Lim
authors.forename: Sung Hoon
authors.initials: SH
authors.lastname: Noh
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Hyung
authors.forename: Ji Yeong
authors.initials: JY
authors.lastname: An
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Lee
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Rha
authors.forename: Kyung Hwan
authors.initials: KH
authors.lastname: Kim
authors.forename: Woong Sub
authors.initials: WS
authors.lastname: Koom
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003131:Combined Modality Therapy; D005260:Female; D005743:Gastrectomy / Q000379:methods*; D006801:Humans; D008197:Lymph Node Excision / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*; D047368:Tumor Burden
keywords: CT-guidance; Gastric cancer; Gross tumor volume; Recurrent node; Vasculature