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: Roos 2456 + Unidos 10396
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 25.04.2016 |
1.001 |
1.014 |
|
|
8.397E+07 |
Seibersdorf |
| 21.06.2018 |
1.001 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
| 14.09.2020 |
1.001 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
| 21.06.2022 |
1.003 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
| 19.06.2024 |
1.002 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
Calibration History: Roos 2456 + Unidoswebline 11
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 25.04.2016 |
1.000 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
| 21.06.2018 |
1.001 |
0.014 |
0.999 |
1.000 |
8.397E+07 |
Seibersdorf |
| 14.09.2020 |
1.001 |
0.014 |
0.999 |
1.000 |
8.397E+07 |
Seibersdorf |
| 21.06.2022 |
1.003 |
0.014 |
0.999 |
1.000 |
8.397E+07 |
Seibersdorf |
| 19.06.2024 |
1.001 |
0.014 |
0.999 |
1.000 |
8.397E+07 |
Seibersdorf |
| 18.06.2026 |
1.002 |
0.014 |
|
|
8.397E+07 |
Seibersdorf |
Calibration History: Roos 2457 + Unidos 10398
| Date |
NW |
U |
ppol (60Co) |
ps (60Co) |
NW' [Gy/C] |
Laboratory |
| 30.06.2015 |
0.997 |
0.014 |
0.999 |
1.000 |
8.355E+07 |
Seibersdorf |
| 13.06.2017 |
1.004 |
0.014 |
1.001 |
1.000 |
8.355E+07 |
Seibersdorf |
| 19.11.2019 |
1.002 |
0.014 |
1.000 |
1.000 |
8.355E+07 |
Seibersdorf |
| 22.06.2021 |
1.003 |
0.014 |
1.000 |
1.000 |
8.355E+07 |
Seibersdorf |
| 19.06.2023 |
1.003 |
0.014 |
1.000 |
1.000 |
8.355E+07 |
Seibersdorf |
| 18.06.2025 |
1.003 |
0.014 |
1.000 |
1.000 |
8.355E+07 |
Seibersdorf |
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. |
| 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). |
