Roos Chamber

Model/Serial: 34001-76 (purchased: 1996, defective: 2014)
Model/Serial: 34001-77 (purchased: 1996)
Model/Serial: 34001-002456 (purchased: 2014)
Model/Serial: 34001-002457 (purchased: 2014)

Description: Verified plane-parallel ionization chamber for absolute dosimetry. We use it with Unidos or Unidoswebline in the water phantom to calibrate linac dose output for electron energies. It may also be used for measurement of depth dose curves, if the field size is not too small. E.g., TrueBeam depth dose curves (Eclipse beam data) for field sizes > 3x3 cm (10FFF: > 10x10 cm) were measured with this detector.

Calibration History: Chamber 76 + Unidos 10396

Date NW U ppol (60Co) ps (60Co) NW' [Gy/C] Laboratory
26.03.1996 1.00 0.04 8.277E+07 PTW
20.05.1996 1.011 0.015 8.277E+07 BEV
03.08.1998 1.01 0.02 8.277E+07 BEV
08.03.2001 1.01 0.02 8.277E+07 BEV
03.02.2003 1.01 0.01 8.277E+07 BEV
05.04.2005 1.01 0.01 8.277E+07 BEV
29.11.2007 1.019 0.014 8.277E+07 Seibersdorf
21.04.2009 1.011 0.014 8.277E+07 Seibersdorf
27.04.2012 1.014 0.014 8.277E+07 Seibersdorf

Calibration History: Chamber 76 + Unidoswebline 11

Date NW U ppol (60Co) ps (60Co) NW' [Gy/C] Laboratory
20.04.2006 1.013 0.014 8.277E+07 Seibersdorf
13.06.2008 1.009 0.014 8.277E+07 Seibersdorf
06.09.2010 1.011 0.014 0.999 1.001 8.277E+07 Seibersdorf
27.04.2012 1.014 0.014 0.999 1.001 8.277E+07 Seibersdorf

60-Co calibration factors

Chamber 77 + Unidos 10398

Date NW U ppol (60Co) ps (60Co) NW' [Gy/C] Laboratory
26.03.1996 1.00 0.04 8.207E+07 PTW
20.05.1996 1.011 0.015 8.207E+07 BEV
20.11.1997 1.013 0.013 8.207E+07 BEV
24.11.1998 1.010 0.02 8.207E+07 BEV
29.11.2000 1.010 0.03 8.207E+07 BEV
06.08.2002 1.020 0.01 8.207E+07 BEV
14.04.2003 1.020 0.01 8.207E+07 BEV
20.04.2005 1.020 0.01 8.207E+07 BEV
22.02.2007 1.012 0.014 8.207E+07 Seibersdorf
20.11.2009 1.015 0.014 0.999 - 8.207E+07 Seibersdorf
27.06.2011 1.015 0.014 1.001 1.001 8.207E+07 Seibersdorf
16.04.2013 1.019 0.014 1.000 1.001 8.207E+07 Seibersdorf

60-Co calibration factors

Note: U = k uc is the expanded uncertainty with the coverage factor k = 2.

Logbook

Date Event
26.03.1996 S/N 76 and S/N 77: initial calibration by PTW.
15.04.2014 S/N 76 marked as defective by Seibersdorf (leakage current too high). No calibration possible.
03.06.2014 Delivery of new Roos chambers S/N 002456 and 002457.

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