title: Pancreatic tumor motion on a single planning 4D-CT does not correlate with intrafraction tumor motion during treatment.
abstract: OBJECTIVE
  To quantify pancreas tumor motion on both a planning 4D-CT and during a single fraction treatment using the CyberKnife linear accelerator and Synchrony respiratory tracking software, and to investigate whether a single 4D-CT study is reliable for determining radiation treatment margins for patients with locally advanced pancreas cancer.
  
  
  METHODS
  Twenty patients underwent fiducial placement, biphasic pancreatic protocol CT scan and 4D-CT scan in the treatment position while free-breathing. Patients were then treated with a single 25 Gy fraction of stereotactic body radiotherapy. Predicted pancreas motion in the superior-inferior (SI), left-right (LR), and anterior-posterior (AP) directions was calculated from the maximum inspiration and maximum expiration 4D-CT scan. For CyberKnife treatments, mean respiratory cycle motion and maximum respiratory cycle motion was determined in the SI, LR, and AP directions.
  
  
  RESULTS
  The range of centroid movement based on 4D-CT in the SI, LR, and AP directions were 0.9 to 28.8 mm, 0.1 to 13.7 mm, and 0.2 to 7.6 mm, respectively. During CyberKnife treatment, in the SI direction, the mean motion of the centroid ranged from 0.5 to 12.7 mm. In the LR direction, the mean motion range was 0.4 to 9.4 mm. In the AP direction, the mean motion range was 0.6 to 5.5 mm. The maximum range of movement (mean) during CyberKnife treatment in the SI, LR, and AP directions were 4.5 to 48.8 mm (mean 20.8 mm), 1.5 to 41.3 mm (mean 11.3 mm), and 1.6 to 68.1 mm (mean 13.4 mm), respectively. Neither the maximum or mean motion correlated with the 4D-CT movement.
  
  
  CONCLUSIONS
  There is substantial respiratory associated motion of pancreatic tumors. The 4D-CT planning scans cannot accurately predict the movement of pancreatic tumors during actual treatment on CyberKnife.
authors.affiliation: Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5152, USA.
authors.forename: A Yuriko
authors.initials: AY
authors.lastname: Minn
authors.forename: Devin
authors.initials: D
authors.lastname: Schellenberg
authors.forename: Peter
authors.initials: P
authors.lastname: Maxim
authors.forename: Yelin
authors.initials: Y
authors.lastname: Suh
authors.forename: Stephen
authors.initials: S
authors.lastname: McKenna
authors.forename: Brett
authors.initials: B
authors.lastname: Cox
authors.forename: Sonja
authors.initials: S
authors.lastname: Dieterich
authors.forename: Lei
authors.initials: L
authors.lastname: Xing
authors.forename: Edward
authors.initials: E
authors.lastname: Graves
authors.forename: Karyn A
authors.initials: KA
authors.lastname: Goodman
authors.forename: Daniel
authors.initials: D
authors.lastname: Chang
authors.forename: Albert C
authors.initials: AC
authors.lastname: Koong
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D009038:Motion; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology / Q000601:surgery*; D011237:Predictive Value of Tests; D011300:Preoperative Care / Q000379:methods; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome