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PTW 34001, 0.35cc Roos Electron Chamber

PTW 34001, 0.35cc Roos Electron Chamber
PTW 34001, 0.35cc Roos Electron Chamber

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PTW 34001, 0.35cc Roos® Electron Chamber.


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PTW 34001, 0.35cc Roos® Electron Chamber.

The Roos electron chamber1 is used as a reference electron chamber.  It is recommended by the IAEA2 for high precision electron dosimetry in radiation therapy.  The chamber has a 4 mm wide guard ring to exclude any perturbation effect even at low electron energies.  The polarity effect is negligible (< 0.5 % at 10 MeV).  The energy response is only influenced by the stopping power ratios water / air.  The chamber is waterproof for absolute dose and depth dose measurements in a water phantom.  The coated acrylic entrance window has a thickness of 1.1 mm.  The nominal useful energy range is from 2 MeV to 45 MeV.  A calibration certificate with a 60Co calibration factor given in absorbed dose to water is included.  Air density correction is required for each measurement.  The chamber cable length is 1.08 m.

Waterproof plane parallel chamber for absolute dosimetry in high-energy electron and proton beams

• Perturbation-free, minimized polarity effect

• Reference chamber for precise absolute electron dosimetry

• Waterproof, wide guard ring design

• Sensitive volume 0.35 cm3, vented to air

• Suitable for use in water and in solid state phantoms

The 34001 Roos chamber is the golden standard for absolute dose measurements in high-energy electron beams.  Modern dosimetry protocols refer to the chamber's design and provide dosimetric correction factors.  Its waterproof design allows the chamber to be used in water or in solid state phantoms.  The Roos chamber is also well suited for the measurement of high-energy photon depth dose curves up to 2.5 mm below the water surface.  The chamber can be used for dose measurements of proton beams.

Type of Product:  vented plane parallel ionization chamber acc IEC 60731
Application:  absolute dosimetry in high-energy electron and proton beams
Measuring Quantities:  absorbed dose to water
Reference Radiation Quality:  60Co
Nominal Sensitive Volume:  0.35 cm3
Design:  Waterproof, vented
Reference Point:  in chamber center, 1.12 mm below surface
Direction of Incidence:  perpendicular to chamber plane, see label FOCUS
Nominal Response:  12 nC/Gy
Long-term Stability:  ≤ 0.5% per year
Chamber Voltage:  200 V nominal ±400 V maximal
Polarity Effect:  < 0.5%
Directional Response in Water:  ≤± 0.1% for chamber tilting ≤± 10°
Leakage Current:  ≤ ± 4 fA
Cable Leakage:  ≤ 1 pC/(Gy∙cm)

Materials and Measures: 
Entrance Window:  1 mm PPMMA, 1.19 mg/cm3, 0.02 mm graphite, 0.82 g/cm3, 0.1 mm varnish, 1.19 g/cm3
Total window area density:  132 mg/cm2
Water-equivalent window thickness:  1.3 mm
Sensitive Volume:  radius 7.5 mm depth 2 mm
Guard ring width:  4 mm

Ion Collection Efficiency at Nominal Voltage: 
Ion collection time:  125 µs

Max. dose rate for:
> 99.5 % saturation:
  5.2 Gy/s
> 99.0 % saturation:  10.4 Gy/s

Max. dose per pulse for:
> 99.5 % saturation:
  0.46 mGy
> 99.0 % saturation:  0.93 mGy

Useful ranges: 
Chamber voltage:  ±50 to 300 V
Radiation quality:  2 - 45 MeV electrons, 60Co - 25 MV photons, 70 - 250 MeV protons
Field size:  4 x 4 cm2 to 40 x 40 cm2
Temperature:  50° - 104° F (10° - 40°C)
Humidity:  10 - 80 %, max 20 g/m3
Air pressure:  700 - 1060 hPa


Please specify which connection end is needed

1The Roos electron chamber was developed in cooperation with Dr. Roos, PTB-Braunschweig, German Federal Institute of Physics and Metrology (National Laboratory of Germany)
2Technical Report No. TRS-381. The Use of Plane Parallel Ionization Chambers in High Energy Electron and Photon Beams, IAEA (International Atomic Energy Agency), Vienna 1997

Data Sheet