Features
· Photon energy ranges from 60Co up to 30 MV
· Establish electron equilibrium for in-air measurement
· Made of PMMA 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 PMMA 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. PMMA material is usually used for build-up caps. PMMA build-up caps are more water equivalent than brass build-up caps, but their size may be disadvantageous when used in small beams.
PMMA build-up caps are available for the any chamber types. The PMMA 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 any chamber types. The wall thicknesses cover the energy range from 60Co to 20 MV photons.