Ion chamber array with 729 ion chambers for precise IMRT plan verification
and LINAC QA

• 27 x 27 (729) vented cubic ionization chambers regularly arranged to MLC leafs across the complete field size of 27 cm x 27 cm
• Avoids detector ageing effects by utilizing ion chambers
• No radiation damage thanks to separated evaluation electronics
• Complete field coverage with Merge seven29

The 2D-ARRAY seven29 is a new concept of an ion chamber matrix in a plane for IMRT verification and quality control in radiation therapy. Utilizing ion chambers avoids radiation defects, the major drawback of solid-state detectors. The vented plane-parallel ion chambers are 5 mm x 5 mm x 5 mm in size, and the center-to-center spacing is 10 mm. In total there are located 729 chambers in a matrix of 27 x 27, providing a maximum field size of 27 cm x 27 cm. The array is only 22 mm flat and 3.2 kg light. The surrounding material is acrylic (PMMA). Due to the square chamber technology the array can be moved 5 mm to close the gaps between chambers. By shifting the array 3 times the whole area is covered. The number of measuring points can be increased to 2916. The 2D-ARRAY seven29 can be used in a flat phantom or in the octagonal phantom OCTAVIUS. With OCTAVIUS the 2D-ARRAY seven29 is suitable for IMAT and Tomotherapy. The 2D-ARRAY seven29 can be used for IMRT plan verification, LINAC QC and online LINAC adjustment. Using the SC Gantry Mount the array can be mounted to the gantry and irradiated under various gantry angles. For patient plan verification in proton and heavy ion therapy a special design 2D-ARRAY xdr is available. This version processes the high dose-per-pulse values in proton and heavy ion therapy. It is compatible with the PTW software.

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Publications

• Two-dimensional ionization chamber arrays for IMRT plan verification
  Bjoern Poppe, Arne Blechschmidt, Armand Djouguela, Ralf Kollhoff, Antje Rubach, Kay C. Willborn, and
  Dietrich Harder
  April 2006, Medical Physics Volume 33, Issue 4, pp. 1005-1015
  
  
• Characterization of a 2D ion chamber array for the verification of radiotherapy treatments
  E Spezi et al 2005, Phys. Med. Biol. 50, 3361-3373
  
  
• Spatial resolution of 2D ionization chamber arrays for IMRT dose verification: single-detector size and sampling step width
  Björn Poppe, Armand Djouguela, Arne Blechschmidt, Kay Willborn, Antje Rühmann and Dietrich Harder
  2007, Phys. Med. Biol. 52, 2921-2935
• Portal dose measurements by a 2D array
  S. Cilla, L. Grimaldi, G. D'Onofrio, P. Viola, M. Craus, L. Azario, A. Fidanzio, G. Stimato, C. Di Gesù, G. Macchia, F. Deodato, A.G. Morganti and A. Piermattei
  March 2007, Physica Medica Volume 23, Issue 1, Pages 25-32