Features
- Sealed ionization chamber for in-vivo measurements
- Waterproof, flexible design for intracavitary use
- Sensitive volume 0.1 cm3, fully guarded
- Radioactive check device (option)
The 23323 micro chamber is used for patient in-vivo measurements in conjunction with an electrometer classified for this purpose. Applications are external beam and brachytherapy dose measurements on the patient’s surface or in body cavities such as the rectum. For the use in body cavities the chamber should be protected by a rubber sleeve. The micro chamber is to be used with a radioactive check device and features a stable response even if the chamber temperature changes.
Specifications
| Type of product | cylindrical ionization chamber acc. IEC 60601-2-9 |
|---|---|
| Application | in-vivo dosimetry in radiotherapy photon beams |
| Measuring quantities | absorbed dose to water, air kerma, exposure |
| Reference radiation quality | 60Co |
| Nominal sensitive volume | 0.1 cm3 |
| Design | waterproof, fully guarded |
| Reference point | on chamber axis, 8 mm from chamber tip |
| Direction of incidence | radial |
| Nominal response | 3.8 nC/Gy |
| Long-term stability | ≤ 1 % per year |
| Chamber voltage | 400 V nominal ± 500 V maximal |
| Photon energy response | < ± 2 % (140 kV … 60Co) |
| Directional response in water | < ± 0.5 % for rotation around the chamber axis and for tilting of the axis up to ± 30° (280 kV) |
| Temperature dependence | < ± 5 % within the useful range |
| Temperature equilibrium time | (2 … 3) min/°C |
| Leakage current | ≤ ± 4 fA |
| Cable leakage | ≤ 1 pC/(Gy·cm) |
Materials and measures
| Wall of sensitive volume | 0.61 mm PMMA, 1.19 g/cm3 0.13 mm graphite, 0.82 g/cm3 |
|---|---|
| Total wall area density | 197 mg/cm2 |
| Dimension of sensitive volume |
radius 1.625 mm length 11.875 mm |
| Central electrode | Al 99.5, diameter 0.8 mm |
| Build-up cap | PMMA, thickness 3 mm |
Ion collection efficiency at nominal voltage
| Ion collection time | 28 µs |
|---|---|
| Max. dose rate for ≥ 99.5 % saturation ≥ 99.0 % saturation |
107 Gy/s |
| Max. dose per pulse for ≥ 99.5 % saturation ≥ 99.0 % saturation |
2.1 mGy 4.2 mGy |
Useful Ranges
| Chamber voltage | ± (100 … 400) V |
|---|---|
| Radiation quality | 66 keV … 50 MV photons |
| Field size | (4 x 4) cm2 … (40 x 40) cm2 |
| Temperature | (10 … 40) °C (50 … 104) °F |
| Humidity | (20 … 75) %, max 20 g/m3 |
| Air pressure | (700 … 1060) hPa |
Options
T48012 Radioactive check device 90Sr
T48002.1.005 Chamber holding device for check device
Parts
TN23323 Micro chamber 0.1 cm3, connecting system BNT
TW23323 Micro chamber 0.1 cm3, connecting system TNC
TM23323 Micro chamber 0.1 cm3, connecting system M
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