A respiratory-gated treatment system for proton therapy

Hsiao Ming Lu, Robert Brett, Gregory Sharp, Soiros Safai, Steve Jiang, Jay Flanz, Hanne Kooy

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Proton therapy offers the potential for excellent dose conformity and reduction in integral dose. The superior dose distribution is, however, much more sensitive to changes in radiological depths along the beam path than for photon fields. Respiratory motion can cause such changes for treatments sites like lung, liver, and mediastinum and thus affect the proton dose distribution significantly. We have implemented and commissioned a respiratory-gated system for range-modulated treatment fields. The gating system was designed to ensure that each gate always contains complete modulation cycles so that for any beam segment the delivered dose has the planned depth-dose distribution. Measurements have been made to estimate the time delays for the various components of the system. The total delay between the actual motion and the beam on/off control is in the range of 65-195 ms. Time-resolved dose measurements and film tests were also conducted to examine the overall gating effect.

Original languageEnglish (US)
Pages (from-to)3273-3278
Number of pages6
JournalMedical physics
Issue number8
StatePublished - 2007


  • Proton gating
  • Time delay

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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