Features
- Small-sized sensitive volume 0.03 cm3, vented to air
- Increased sensitive volume for low dose rate measurements
- Aluminum central electrode
The 31015 PinPoint chamber is used in cases where higher signal levels than obtained with the 31014 and 31016 chambers are required. The 31015 is ideal for dose measurements in small fields as encountered e.g. in IORT, IMRT and stereotactic beams. Relative dose distributions can be measured with high spatial resolution if the chamber is moved perpendicular to the chamber axis. The waterproof, fully guarded chamber can be used in air, solid state phantoms and in water.
Specifications
| Type of product | vented cylindrical ionization chamber |
|---|---|
| Application |
dosimetry in high-energy photon beams |
| Measuring quantities | absorbed dose to water, air kerma, exposure |
| Reference radiation quality | 60Co |
| Nominal sensitive volume | 0.03 cm3 |
| Design | waterproof, vented, fully guarded |
| Reference point | on chamber axis, 3.4 mm from chamber tip |
| Direction of incidence | radial |
| Pre-irradiation dose | 2 Gy |
| Nominal response | 800 pC/Gy |
| Long-term stability | ≤ 1 % per year |
| Polarity effect | < 1 % |
| Chamber voltage | 400 V nominal ± 500 V maximal |
| Directional response in water | ≤ ± 0.5 % for rotation around the chamber axis, ≤ ± 1 % for tilting of the axis up to ± 20° |
| Leakage current | ≤ ± 4 fA |
| Cable leakage | < 1 pC/(Gy·cm) |
Materials and measures
| Wall of sensitive volume | 0.57 mm PMMA, 1.19 g/cm3 0.09 mm graphite, 1.85 g/cm3 |
|---|---|
| Total wall area density | 85 mg/cm2 |
| Dimensions of sensitive volume |
radius 1.45 mm length 5 mm |
| Central electrode | Al 99.98, diameter 0.3 mm |
| Build-up cap | PMMA, thickness 3 mm |
Ion collection efficiency at nominal voltage
| Ion collection time | 50 µs |
|---|---|
| Max. dose rate for ≥ 99.5 % saturation ≥ 99.0 % saturation |
29 Gy/s |
| Max. dose per pulse for ≥ 99.5 % saturation ≥ 99.0 % saturation |
1.2 mGy 2.3 mGy |
Useful Ranges
| Chamber voltage | ± (100 … 400) V |
|---|---|
| Radiation quality | 60Co … 50 MeV photons |
| Field size | (2 x 2) cm2 … (30 x 30) cm2 |
| Temperature | (10 … 40) °C (50 … 104) °F |
| Humidity |
(10 … 80) %, max 20 g/m3 |
| Air pressure | (700 … 1060) hPa |
Parts
TN31015 PinPoint chamber 0.03 cm3, connecting system BNT
TW31015 PinPoint chamber 0.03 cm3, connecting system TNC
TM31015 PinPoint chamber 0.03 cm3, connecting system M
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