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PTW 30015, 1.0 cc Rigid Stem Chamber

PTW 30015, 1.0 cc Rigid Stem Chamber
PTW 30015, 1.0 cc Rigid Stem Chamber

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PTW 30015, 1.0 cc Rigid Stem Chamber.


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PTW 30015, 1.0 cc Rigid Stem Chamber.

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

The rigid stem chambers are designed as reference chambers for absolute dosimetry to be used in radiation therapy or by secondary standard dosimetry laboratories (SSDL).  They have very small variations of response with radiation quality from low X-ray energies up to high-energy photon and electron radiation.  The nominal useful energy range is from 30 kV to 50 MV photons and 6 MeV to 50 MeV electrons.  Both chambers are shaped cylindrically (thimble chambers).  The wall material is graphite with a protective acrylic cover.  The electrodes are made of aluminum.  The guard rings are designed up to the measuring volume.  Both chambers are constructed with a long stem of approx. 25 cm length for easy mounting in the radiation beam.  An acrylic build-up cap for in-air measurement in 60Co beams is included with each chamber, as well as a calibration certificate for calibration in absorbed dose to water or in air kerma.  Air density correction is required for each measurement.

High-volume therapy chamber for absolute dosimetry in high-energy photon and electron beams.

• Fully guarded chamber

• Sensitive volume 1.0 cm3, vented to air

• Acrylic wall, graphite

• Aluminum central electrode

The 30015 Rigid Stem chamber is used for absolute dose measurements in radiation therapy.  Correction factors needed to determine absorbed dose to water or air kerma are published in the pertinent dosimetry proto-cols.  The acrylic chamber wall ensures the ruggedness of the chamber.  The chamber is designed for the use in solid state phantoms and is therefore not waterproof.

Type of Product:  vented cylindrical ionization chamber
Application:  absolute dosimetry in radiotherapy beams
Measuring Quantities:  absorbed dose to water, air kerma, exposure
Reference Radiation Quality:  60Co
Nominal Sensitive Volume:  1.0 cm3
Design:  not waterproof, vented, fully guarded
Reference Point:  on chamber axis, 11.5 mm from chamber tip
Direction of Incidence:  radial
Nominal Response:  31.9 nC/Gy
Long-term Stability:  ≤ 1% per year
Chamber Voltage:  400 V nominal ±600 V maximal
Polarity Effect:  ≤ 1%
Photon Energy Response:  ≤ ± 2%, 70kV - 250 kV ≤ ± 4%, 200kv - 60Co
Directional Response in Solid State Phantom:  ≤± 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:  0.4 mm PMMA, 1.19 g/cm3, 0.135 mm graphite, 1.85 g/cm3
Total wall area density:  73 mg/cm2
Dimension of Sensitive Volume:  radius 3.95 mm depth 22 mm
Central Electrode:  Al 99.98, diameter 1.1 mm
Build-Up Cap:  PMMA, thickness 3 mm

Ion Collection Efficiency at Nominal Voltage: 
Ion collection time:  236 µs

Max. dose rate for:
> 99.5 % saturation:
  1.5 Gy/s
> 99.0 % saturation:  2.9 Gy/s

Max. dose per pulse for:
> 99.5 % saturation:
  0.25 mGy
> 99.0 % saturation:  0.49 mGy

Useful ranges: 
Chamber voltage:  ±100 to 600 V
Radiation quality:  70 keV - 50 MV Photons, 10 - 45 MeV Electrons
Field size:  5 x 5 cm2 to 40 x 40 cm2
Temperature:  50° - 104° F (10° - 40°C)
Humidity:  20 - 80 %, max 20 g/m3
Air pressure:  700 - 1060 hPa


 Please specify which connection end is needed

Data Sheet


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