Build-Up Caps for Ionization Chambers

Features

• Photon energy ranges from ⁶⁰Co up to 30 MV
• Establish electron equilibrium for in-air measurement
• Suitable for PTW Farmer and semiflex chambers
• Made of acrylic or brass

Build-up caps are used with thimble ionization chambers for in-air measurements in photon beams when electron equilibrium is desired. Each standard delivery of a thimble chamber includes an appropriate acrylic build-up cap for ⁶⁰Co. Optionally, a variety of build-up caps is available for different ionization chamber types and for different photon energy ranges. Acrylic material is usually used for build-up caps. Acrylic build-up caps are more water-equivalent than brass build-up caps, but their size may be disadvantageous when used in small beams. Acrylic build-up caps are available for the chamber types:

• 0.6 cm³ PTW Farmer chambers
• 0.125 cm³ and 0.3 cm³ Semiflex chambers

The acrylic build-up caps are designed with wall thicknesses for various energy ranges from ⁶⁰Co up to 30 MV photons.

Brass build-up caps are available for the chamber types:

• 0.125 cm³ and 0.3 cm³ Semiflex chambers

The wall thicknesses cover the energy range from ⁶⁰Co to 20 MV photons.

Parts

Variety of acrylic and brass build-up caps upon request

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