title: Planning study for Merkel cell carcinoma based on the relapse pattern.
abstract: To develop a technique for radiation (RT) of in-transit path ways (IT) in Merkel cell carcinoma.
  
  
  
  In the planning study, IT were ink-marked on the skin during sentinel lymphscintigraphy and wire-marked in planning-CT. Pre- and post-operative planning-CTs were acquired. The clinical target volume (CTV) included tumor bed plus safety margin, IT and draining nodes, the planning volume (PTV) the CTV plus 0.5-1cm margin. VMAT plans with 2-3 arcs were analyzed.
  
  
  
  A planning study was performed for five pts. including two pts. with primary tumor (PT) in head and neck, 1 pt. each with PT of elbow, forearm and upper leg respectively. Plans showed satisfactory PTV coverage: Dmean100%±0%, D98%92.4%±2.24%, homogeneity index (HI) 0.095±0.01, conformation number (CN) 0.84±0.01 and conformality index (CI) 0.95±0.01.
  
  
  
  The planning study confirms feasibility of highly conformal irradiation of IT pathways based on individualized target delineation. Currently, patients referred for non-metastatic MCC are encouraged to enroll in a prospective clinical study that evaluates the feasibility of radiation of IT pathways.
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany. Electronic address: Ulrike.hoeller@charite.de.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Hoeller
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: Schubert
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Mueller
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Budach
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany.
authors.forename: Pirus
authors.initials: P
authors.lastname: Ghadjar
authors.affiliation: Nuclear Medicine, Charité University Medicine Berlin, Germany.
authors.forename: Winfried
authors.initials: W
authors.lastname: Brenner
authors.affiliation: Radiation Oncology, Charité University Medicine Berlin, Germany.
authors.forename: Wolf
authors.initials: W
authors.lastname: Kuschke
mesh_terms: D015266:Carcinoma, Merkel Cell / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D006801:Humans; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012008:Recurrence; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed
keywords: In transit metastases; Merkel cell carcinoma; Planning study; Sentinel node scintigraphy