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PTW 30011 Farmer Chamber

PTW 30011 Farmer Chamber
PTW 30011 Farmer Chamber

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PTW 30011 Farmer® Chamber.


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PTW 30011 Farmer® Chamber.

The 0.6 cm3 PTW Farmer chambers are designed for absolute photon and electron dosimetry with therapy dosemeters.  Three chamber types for measurements in air or in solid state phantom material are available.

Thimble chambers for measuring high-energy photon and electron radiation in air or in phantom material.

• Fully guarded chamber

• Vented sensitive volumes of 0.6 cm3

• Suitable as therapy chambers for use in solid phantoms

• Flat energy response

• Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry protocols.

• The chambers are designed for the use in solid state phantoms and are not waterproof.

The 30011 is a pure graphite therapy chamber.  The 30011 all graphite Farmer chamber is used for absolute dose measurements in radiation therapy in cases where a minimum of different materials in the radiation field is desired.  Due to the sole use of graphite the energy response of the chamber at energies below 60Co varies stronger than that of chambers with an aluminum electrode.  The 30011 is used for therapy dosimetry, where a completely graphite-built chamber is required.  The nominal photon energy range is from 140 kV to 50 MV.

The electron energy range of all chambers is from 10 MeV to 45 MeV.  The chambers type 30011 and 30012 with their graphite caps are of delicate construction and should be handled with extreme care.  The guard rings of all chamber types are designed up to the measuring volume.  An acrylic build-up cap for in-air measurement in 60Co beams is included with each chamber, as well as a calibration certificate.

Connection Type:  Customer to Specify
Type of Product:  vented cylindrical ionization chamber acc. IEC 60731
Application:  absolute therapy dosimetry in solid state phantoms and air
Measuring Quantities:  absorbed dose to water, air kerma, exposure
Reference Radiation Quality:  60Co
Nominal Sensitive Volume:  0.6 cm3
Design:  NOT waterproof, vented fully guarded
Reference Point:  on chamber axis, 13mm from tip
Direction of Incidence:  radial
Nominal Response:  20 nC/Gy
Long-term Stability:  ≤0.5 % per year
Chamber Voltage:  400 V nominal ±500 V maximal
Polarity Effect at 60Co:  < 0.5%
Photon Energy Response:  ≤ ± 12% (280 kV to 60Co)
Directional Response in  Solid State Phantom:  ≤ ± 0.5% for rotation around the chamber axis and for tilting of the axis up to ± 5°
Leakage Current:  ≤ ± 4 fA
Cable Leakage:  ≤ 1 pC/(Gy∙cm)

Materials and Measures:  0.425 mm graphite
Wall of Sensitive Volume:  1.85 g/cm3

Total Wall Area Density:  79 mg/cm2
Dimension of Sensitive Volume:  radius 3.05 mm, length 23.0 mm
Central Electrode:  graphite, diameter 1.0 mm
Build-up Cap:  PMMA, thickness 4.55 mm

Ion Collection Efficiency at Nominal Voltage: 
Ion collection time:  140 µs

Max. dose rate for:
> 99.5 % saturation:
  5 Gy/s
> 99.0 % saturation:  10 Gy/s

Max. dose per pulse for:
> 99.5 % saturation:
  0.46 mGy
> 99.0 % saturation:  0.91 mGy

Useful ranges: 
Chamber voltage:  ±100 to 400 V

Radiation quality:  140 kV to 50 MV photons (10 to 45) MeV electrons (50 to 270) MeV protons
Field size:  (5 x 5) 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

Data Sheet


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