0.3 cm3 Chamber
Model/Serial: 31003-939 (purchased: 1996)
Model/Serial: 31003-940 (purchased: 1996, defective: 2003)
Model/Serial: 31013-053 (purchased: 2003)
Description: Verified ionization chamber for absolute dosimetry. We use it with Unidos or Unidoswebline in the water phantom to calibrate linac dose output for photon energies.
Calibration History: Chamber 939 + Unidos 10396
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 26.03.1996
| 1.00 |
0.04 |
|
|
9.576E+07 |
PTW |
| 20.05.1996 |
1.02 |
0.015 |
|
|
9.576E+07 |
BEV |
| 03.08.1998 |
1.03 |
0.02 |
|
|
9.576E+07 |
BEV |
| 08.03.2001 |
1.03 |
0.02 |
|
|
9.576E+07 |
BEV |
| 03.02.2003 |
1.03 |
0.01 |
|
|
9.576E+07 |
BEV |
| 05.04.2005 |
1.03 |
0.01 |
|
|
9.576E+07 |
BEV |
| 29.11.2007 |
1.032 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 21.04.2009 |
1.028 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 27.04.2012 |
1.030 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 15.04.2014 |
1.029 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 25.04.2016 |
1.032 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 21.06.2018 |
1.035 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 14.09.2020 |
1.033 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 21.06.2022 |
1.034 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 19.06.2024 |
1.033 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
Calibration History: Chamber 939 + Unidoswebline 11
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 20.04.2006 |
1.027 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 13.06.2008 |
1.030 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
| 06.09.2010 |
1.032 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 27.04.2012 |
1.029 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 15.04.2014 |
1.029 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 25.04.2016 |
1.031 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 21.06.2018 |
1.034 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 14.09.2020 |
1.033 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 21.06.2022 |
1.034 |
0.014 |
0.999 |
1.000 |
9.576E+07 |
Seibersdorf |
| 19.06.2024 |
1.033 |
0.014 |
0.998 |
1.000 |
9.576E+07 |
Seibersdorf |
| 18.06.2026 |
1.034 |
0.014 |
|
|
9.576E+07 |
Seibersdorf |
Calibration History: Chamber 53 + Unidos 10398
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 12.03.2003 |
1.000 |
0.022 | |
|
9.767E+07 |
PTW |
| 14.04.2003 |
1.020 |
0.01 |
|
|
9.767E+07 |
BEV |
| 20.04.2005 |
1.020 |
0.01 |
|
|
9.767E+07 |
BEV |
| 22.02.2007 |
1.016 |
0.014 |
|
|
9.767E+07 |
Seibersdorf |
| 20.11.2009 |
1.016 |
0.014 |
0.998 |
1.000 |
9.767E+07 |
Seibersdorf |
| 27.06.2011 |
1.019 |
0.014 |
0.997 |
1.000 |
9.767E+07 |
Seibersdorf |
| 16.04.2013 |
1.022 |
0.014 |
0.997 |
1.000 |
9.767E+07 |
Seibersdorf |
| 30.05.2015 |
1.013 |
0.014 |
0.999 |
0.999 |
9.767E+07 |
Seibersdorf |
| 13.06.2017 |
1.020 |
0.014 |
0.998 |
0.999 |
9.767E+07 |
Seibersdorf |
| 19.11.2019 |
1.018 |
0.014 |
0.998 |
1.000 |
9.767E+07 |
Seibersdorf |
| 22.06.2021 |
1.021 |
0.014 |
0.999 |
0.999 |
9.767E+07 |
Seibersdorf |
| 19.06.2023 |
1.019 |
0.014 |
0.997 |
0.999 |
9.767E+07 |
Seibersdorf |
| 18.06.2025 |
1.023 |
0.014 |
0.999 |
1.000 |
9.767E+07 |
Seibersdorf |
Notes
- U = k uc is the expanded uncertainty with the coverage factor k = 2.
- The first calibration of the chamber was performed in Germany (PTW). Immediately after purchase, the chamber was verified and once more calibrated in Austria. The apparent "jump" in the 60-Co calibration factor Nw can be partly attributed to the different positioning rules in the two countries during the 60-Co calibration procedure.
In the figure below, the chamber is shown during calibration. In Austria (left), it is positioned with the effective point of measurement in 5 cm depth (well, not really, but a correction is made so that the effect is the same). In Germany (right), the chamber's reference point (= the chamber axis) is positioned at 5 cm depth. The result is, that the calibration factor Nw in Germany is a little bit smaller than the Austrian Nw. By how much? By the factor pdis = 1 - 0.003 r, where r is the chamber's inner radius in millimeters.
For the 31003/31013 chambers, r = 2.75 mm, pdis = 1 - 0.003 * 2.75 = 0.9918 or NwGER = 0.9918 * NwAUT.
Logbook
| Date |
Event |
| 26.03.1996 |
S/N 939 and S/N 940: initial calibration by PTW. |
| 2003 |
S/N 940 defective, replaced by S/N 53. |
| 2026 |
Due to increasing costs for verification and calibration, we phased out Unidos 10396 in 2026. For the remaining electrometer/chamber combinations in use, we stopped ordering the correction factors ppol (60Co) and ps (60Co). These factors are very stable (see tables). |
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