MRI quantification of pancreas motion as a function of patient setup for particle therapy -a preliminary study

Giulia Fontana*, Marco Riboldi, Chiara Gianoli, Cezarina I. Chirvase, Gaetano Villa, Chiara Paganelli, Paul E. Summers, Barbara Tagaste, Andrea Pella, Piero Fossati, Mario Ciocca, Guido Baroni, Francesca Valvo, Roberto Orecchia

*Corresponding author for this work

Research output: Journal article (peer-reviewed)Journal article

24 Citations (Scopus)


Particle therapy (PT) has shown positive therapeutic results in local control of locally advanced pancreatic lesions. PT effectiveness is highly influenced by target localization accuracy both in space, since the pancreas is located in proximity to radiosensitive vital organs, and in time as it is subject to substantial breathing-related motion. The purpose of this preliminary study was to quantify pancreas range of motion under typical PT treatment conditions. Three common immobilization devices (vacuum cushion, thermoplastic mask, and compressor belt) were evaluated on five male patients in prone and supine positions. Retrospective four-dimensional magnetic resonance imaging data were reconstructed for each condition and the pancreas was manually segmented on each of six breathing phases. A k-means algorithm was then applied on the manually segmented map in order to obtain clusters representative of the three pancreas segments: head, body, and tail. Centers of mass (COM) for the pancreas and its segments were computed, as well as their displacements with respect to a reference breathing phase (beginning exhalation). The median three-dimensional COM displacements were in the range of 3 mm. Latero-lateral and superior-inferior directions had a higher range of motion than the anterior-posterior direction. Motion analysis of the pancreas segments showed slightly lower COM displacements for the head cluster compared to the tail cluster, especially in prone position. Statistically significant differences were found within patients among the investigated setups. Hence a patient-specific approach, rather than a general strategy, is suggested to define the optimal treatment setup in the frame of a millimeter positioning accuracy.

Original languageEnglish
Pages (from-to)60-75
Number of pages16
JournalJournal of Applied Clinical Medical Physics
Issue number5
Publication statusPublished - 08 Sept 2016
Externally publishedYes


  • 4D MRI
  • Pancreas motion
  • Pancreas segmentation
  • Pancreatic cancer
  • PT immobilization
  • Radiotherapy Dosage
  • Pancreatic Neoplasms/radiotherapy
  • Radiotherapy Planning, Computer-Assisted/methods
  • Patient Positioning
  • Radiotherapy, Intensity-Modulated/methods
  • Humans
  • Magnetic Resonance Imaging/methods
  • Male
  • Immobilization/instrumentation
  • Algorithms
  • Image Processing, Computer-Assisted/methods
  • Radiotherapy Setup Errors/prevention & control
  • Retrospective Studies
  • Respiration

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology, Nuclear Medicine and Imaging


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