Low energy unflattened beam for portal imaging

Alex Tsechanski, Sergio Faermann, Yanai Krutman

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


An improved low energy unflattened x-ray port has been developed and installed in a Clinac 18, Varian Associates. The nominal accelerating potential was lowered to 4 MV in order to increase the relative low energy contribution (≤ 150 keV)to the whole spectrum. Electron beam energy change was performed by decreasing the amount of RF power applied to the accelerating guide by means of the shunt tee drive assembly. Bending magnet DC current was matched (decreased) by 40% as compared to the routine 10 MV therapeutic mode. Measurements of the PDD and beam profile were performed, comparing well with the 4 MV specifications. Portal films taken with a scale- tray and an anthropomorphic phantom clearly show the improvement in contrast and resolution obtained with the new port.

Original languageEnglish
Pages (from-to)162-165
Number of pages4
JournalPhysica Medica
Issue numberSUPPL. 1
StatePublished - 1 Jan 1997


  • Bend magnet
  • Low energy option
  • Portal imaging
  • RF power

ASJC Scopus subject areas

  • Biophysics
  • Radiology Nuclear Medicine and imaging
  • Physics and Astronomy (all)


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